Dissertations / Theses on the topic 'Acute kidney failure'

Acute kidney injury (AKI) is serious and complicates up to 1 in 7 hospital admissions. It is usually diagnosed from rapidly deteriorating blood tests. Much of the focus of clinical research into AKI has been on strategies to improve recognition and timely intervention. However, emerging evidence suggests that even when people survive AKI, they remain at an elevated risk of poor long-term outcomes. The aim of this thesis was to determine which people with AKI have an ongoing increased risk of poor outcomes (mortality, kidney failure, recurrent illness episodes) after hospital discharge. The design was a population-based data-linkage cohort study involving the Grampian Laboratory Outcomes Morbidity and Mortality Study (GLOMMS-II). Data linkages included population biochemistry, hospital episode data, mortality records, intensive care records and renal registry data from 1999-2013. A cohort of 17,630 people hospitalised in 2003 were followed through to 2013. Outcomes were mortality, progression of kidney disease and unplanned hospital readmission episodes. There have been several novel research outputs. I evaluated and adapted international AKI criteria for use in large population biochemistry datasets. I developed a clinical risk prediction model for unplanned readmissions after hospital discharge, for which AKI was a strong independent predictor. I described long-term survival after AKI, showing that people with AKI (vs no AKI) have a substantially higher risk of death in the first year, but diminishing excess risk thereafter. Finally, I conducted a novel analysis of renal prognosis after AKI, showing that mortality and non-recovery are more common than subsequent renal progression after AKI, but that renal progression is nevertheless increased after AKI. Overall, AKI is a serious condition and marker of people who have a long lasting poorer prognosis. The first year after discharge is a period of particularly heightened risk that could potentially be targeted with initiatives to improve care.

Thematic Paper (M.C.T.M. (Clinical Tropical Medicine))--Mahidol University, 2008.
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Introduction: Chronic kidney disease (CKD) and congestive heart failure (CHF) patients have higher serum B-type natriuretic peptide (BNP), which alters the test interpretation. We aim to define BNP cutoff levels to diagnose acute decompensated heart failure (ADHF) in CKD according to CHF subtype: heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF). Material and methods: We reviewed 1,437 charts of consecutive patients who were admitted for dyspnea. We excluded patients with normal kidney function, without measured BNP, echocardiography, or history of CHF. BNP cutoff values to diagnose ADHF for CKD stages according to CHF subtype were obtained for the highest pair of sensitivity (Sn) and specificity (Sp). We calculated positive and negative likelihood ratios (LR+ and LR–, respectively), and diagnostic odds ratios (DOR), as well as the area under the receiver operating characteristic curves (AUC) for BNP. Results: We evaluated a cohort of 348 consecutive patients: 152 had ADHF, and 196 had stable CHF. In those with HFpEF with CKD stages 3–4, BNP < 155 pg/ml rules out ADHF (Sn90%, LR– = 0.26 and DOR = 5.75), and BNP > 670 pg/ml rules in ADHF (Sp90%, LR+ = 4 and DOR = 6), with an AUC = 0.79 (95% CI: 0.71–0.87). In contrast, in those with HFrEF with CKD stages 3–4, BNP < 412.5 pg/ml rules out ADHF (Sn90%, LR– = 0.19 and DOR = 9.37), and BNP > 1166.5 pg/ml rules in ADHF (Sp87%, LR+ = 3.9 and DOR = 6.97) with an AUC = 0.78 (95% CI: 0.69–0.86). All LRs and DOR were statistically significant. Conclusions: BNP cutoff values for the diagnosis of ADHF in HFrEF were higher than those in HFpEF across CKD stages 3–4, with moderate discriminatory diagnostic ability.
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During the last ten years, several patients have presented to the Renal Unit of Groote Schuur Hospital with acute renal failure following the use of traditional (N'anga or Gqirha) medication. The history together with abnormal liver-function tests and renal failure was thought to be suggestive of a toxic aetiology. The specific toxin however remained unknown, until during the admission of one patient, a relative brought in the medication, analysis of which revealed a high concentration of potassium dichromate. Subsequently elevated levels of chromium were demonstrated by atomic absorption spectrometry in the blood and urine of this patient. Following this case there have been six further cases of acute renal failure resulting from use of dichromate containing traditional remedies. These remedies were obtained from a variety of sources including street-hawkers, herbal chemists, and traditional healers. Clinical and laboratory data relating to these seven patients will be presented.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
A guanilina e a uroguanilina foram recentemente descobertas, respectivamente, no intestino e na urina, (Currie et al., 1992; Hamra et al., 1993). Fazem parte da famÃlia de peptÃdeos que ativam a guanilato ciclase de membrana (GC-C), aumentando os nÃveis intracelulares de cGMP (Schulz et al., 1990). EstÃo presentes em diversos tecidos, como respiratÃrio, linfonodos, testÃculos, cÃrebro e medula adrenal (Field et a.l., 1978; Forte et al., 1988, 1989; Hamra et al., 1993; Schulz et al., 1992). Foi comprovado que adicionando uma lisina na porÃÃo N-terminal, obtÃm-se um anÃlogo mais estÃvel e potente que a guanilina. O objetivo desse estudo à pesquisar os efeitos renais de um novo anÃlogo, ser-thr-lys-guanilina em sistema de perfusÃo. Os rins foram perfundidos com a soluÃÃo de Krebs-Henseleit modificada com 6g% de albumina bovina. Os dados foram comparados atravÃs de teste t de Student e ANOVA, com significÃncia p<0,05. Na dose de 0,1 Âg/mL, esse peptÃdeo apresentou efeitos similares aos da uroguanilina, na dose de 0,5 Âg/mL, em todos os parÃmetros testados. Ambas causaram aumento na pressÃo de perfusÃo (PP: de 101,5Â3,7 para 111Â2,9mmHg; de 101,2Â2,6 para 113,4Â2,5mmHg), no fluxo urinÃrio (FU: de 0,158Â0,016 para 0,223Â0,01 mL.g-1.min-1; de 0,16Â0,016 para 0,226Â0,2mL.g-1.min-1) e diminuiÃÃo no transporte tubular total e proximal de sÃdio (%TNa+: de 0,774Â0,06 para 0,724Â0,035; de 0,735Â0,065 para 0,773Â0,084), potÃssio (%TK+: de 66,89Â2,77 para 47,29Â3,34; de 63,54Â3,82 para 42,54Â8,14) e cloreto (%TCl-: de 85,69Â1,19 para 73,59Â2,63). Esses resultados foram similares aos previamente descritos apÃs a administraÃÃo da toxina termo-estÃvel da Escherichia coli (STa), guanilina, uroguanilina e lys-guanilina no mesmo sistema (Lima et al., 1992; Fonteles et al., 1996 e 1998). A dose maior (1 Âg/mL) causou aÃÃo antidiurÃtica (FU: de 0,165Â0,004 para 0,111Â0,009mL.g-1.min-1) e nenhum efeito sobre o transporte de sÃdio, embora a diminuiÃÃo na reabsorÃÃo tubular de potÃssio (%TK+: de 72,29Â1,2 para 49,73Â6,75) e cloreto (%TCl-: de 85,96Â0,79 para 81,9Â1,47) continuassem presentes. Nesta dose, nÃo apenas bloqueou o efeito diurÃtico da uroguanilina, como continuou causando um efeito antidiurÃtico significativo (FU: de 0,168Â0,004 para 0,116Â0,006). No entanto, nÃo foi capaz de bloquear os efeitos natriurÃticos da uroguanilina (%TNa+: de 85,35Â2,55 para 79,92Â1,05). O mecanismo de aÃÃo renal preciso dos peptÃdeos da famÃlia das guanilinas ainda nÃo foi completamente esclarecido. Sabe-se que esses peptÃdeos se ligam aos receptores GC-C (Schulz et al., 1990), porÃm hà indÃcios de que existam outras vias de aÃÃo renal, independentes desse receptor. Hà ainda a possibilidade de que haja duas entidades agindo de modo antagÃnico no sistema. Talvez haja a necessidade de isolÃ-los. A descoberta dos peptÃdeos da famÃlia das guanilinas promoveu avanÃos significativos na compreensÃo da regulaÃÃo endÃgena dos transportes de Ãgua e eletrÃlitos. O completo esclarecimento do seu mecanismo de aÃÃo renal oferece perspectivas reais para o tratamento de doenÃas como a hipertensÃo arterial.
Guanylin and uroguanylin are members of a family of peptides that stimulates cGMP production in several organic tissues, as intestine, kidney, airway, linfonodes, testis, brain and adrenal medulla (Field et a.l., 1978; Forte et al., 1988, 1989; Hamra et al., 1993; Schulz et al., 1992). Their 15 amino acid structures have been identified from rat intestine and opossum urine, respectively (Currie et al., 1992; Hamra et al., 1993), and they seem to be the link between intestine and kidney functions in controling blood pressure, as the âintestinal natriuretic hormoneâ suggested by some authors (Carey, 1978; Lennane et al., 1975). It was demonstrated that a Lysine-1 analog of guanylin is a more potent natriuretic and kaliuretic peptide. The aim of this study was to evaluate the renal effects of a novel analog of guanylin: ser-thr-lys-guanylin. Its effects were examined using isolated perfused kidneys from Wistar rats. All experiments were preceded by a 30 minutes internal control period and an external control group (C), in which the kidneys were perfused only with Krebs-Henseleit solution containing 6g% of a previously dialysed bovine albumine serum. The data was analyzed by Student t-test and ANOVA. The level of significance was set at p<0,05. Ser-thr-lys-guanylin, at the lowest dose (0.1 Âg/mL) and uroguanylin (0.5Âg/mL) caused similar effects. Both groups were able to increase perfusion presure (PP: 101.5Â3.7 to 111Â2.9mmHg; 101.2Â2.6 to 113.4Â2.5 mmHg), urinary flow (UF: 0.158Â0.016 to 0.223Â0.019 mL.g-1.min-1; 0.16Â0.016 to 0.226Â0.2mL.g-1.min-1) and to decrease sodium (%TNa+: 0.774Â0.06 to 0.724Â0.035; 0.735Â0.065 to 0.773Â0.084), potassium (%TK+: 66.89Â2.77 to 47.29Â3.34; 63.54Â3.82 to 42.54Â8.14) and cloride (%TCl-: 85.69Â1.19 to 73.59Â2.63) tubular reabsorption. Similar effects were also found in response to the Escherichia coli heat-stable enterotoxin (STa), guanylin, uroguanylin and lys-guanylin in the same system (Lima et al., 1992; Fonteles et al., 1996 e 1998). However, a greater dose (1Âg/mL), not only caused signifcantly decrease in the urinary flow (UF: 0.165Â0.004 to 0.111Â0.009 mL.g-1.min-1), but was also able to block the diuretic effects of uroguanylin (UF: 0.168Â0.004 to 0.116Â0.006 mL.g-1.min-1), although it still decreased potassium (%TK+: 72.29Â1.2 to 49.73Â6.75) and cloride(%TCl-: 85.96Â0.79 to 81.9Â1.47) tubular reabsorption. The precise renal mecanism of action of this family of peptides has not yet been fully elucidated. Deletion of GC-C genes in transgenic mice reveals that intestinal fluid secretion responses to STa are completely lost (Schulz et al., 1997 & Mann et al., 1997), but the natriuretic responses to STa and uroguanylin are retained (Carrithers et al., 1999), suggesting that other receptors are envolved. There is a possibility that there are to peptides causing antagonic effects. Further isolation may be necessary. Further studies are required to elucidate the specific renal mechanism of action of this new peptide. The discovery of guanylin and its family has promoted significant advances in the understanding of endogenous control of salt, water and eletrolites. The study of its analogs in perfused rat kidneys could help in elucidating their specific renal mecanism of action and bring great perspectives in the control of blood pressure.

Acute Kidney Disease (CKD) is a major public health problem that affects some 3-7% of patients admitted to the hospital and approximately 25-30% of patients in the intensive care unit. None of the existing therapies are exempt from side effects and kidney physiological functionality is never restored. Transplantation has been reported as the preferred cure for CKD management but organ shortage and risks due to the immunosuppressive therapy makes it far from being the perfect treatment for ESRD. In this study we have focused our attention on finding novel strategies, in vitro and in vivo, to obtain kidney regeneration in case of acute and chronic kidney damage. First we have demonstrated the ability of hAFSCs to survive, proliferate and integrate into the embryonic kidney, while it undergoes organ development, in an in vitro culture system. We observed the presence of hAFSCs within kidney primordial, including tubules and developing nephrons. Thus, hAFSCs seem to have the capacity to undergo the expected mesenchymal to epithelial transition that occurs in normal renal development and are induced to express important early kidney markers such as GDNF, ZO-1 and Claudin. Moreover, hAFSCs do not appear to require prior genetic modification or exogenous production of kidney proteins for their differentiation to occur. This is a very important advantage that hAFSCs have for potential future regenerative or bioengineering application. With the in vivo experiments, we have demonstrated that early direct injection of hAFSCs into the kidney strongly ameliorates ATN injury as reflected by more rapid resolution of tubular structural damage and by normalization of creatinine and BUN levels. In addition, our data show evidence of immunomodulatory and antinflammatory effect of hAFSCs, at an early time point, comparable in magnitude to endogenous cytokine production. Understanding how donor and host cells combine to attenuate tubular damage may lead eventually to the application of hAFSCs for therapeutic purposes in acute kidney diseases. Nonetheless, beside the presence of a small number (1%) of cells with pluripotent characteristics, the composition of the other 99% of Amniotic Fluid cells is diverse, with a great amount of cells exhibiting commitment to a defined germ line or cellular endpoint. There seems to be clear evidence for the existence of progenitor cells in Amniotic Fluid, which can give rise to different cell types of mature organs. By 17 weeks of gestation is notable an increase tissue specific cellular presence and this data may indicate that the choice of the time point for cell selection is fundamental. In addition, we demonstrated in the amniotic fluid, the presence of a renal population with specific traits of commitment. In particular, the presence of podocytes at both undifferentiated and almost mature stages could favour their use for kidney regeneration in vitro and in vivo animal models. The presence and identification of specific renal progenitor cells in the Amniotic Fluid, committed to different compartments of the kidney environment, could represent a valuable new tool for regenerative purposes with regards to the treatment of a broad range of renal diseases. The discovery of renal specific progenitor cells within Amniotic Fluid could bring a breakthrough in the study for novel and more selective approaches in the renal therapy. However, the real pluripotential capability of these progenitors cells, in particular the kidney progenitors presenting more differentiation characteristics, has to be established. Moreover, their potential for survival, proliferation, integration, and differentiation needs to be assessed in in vivo models involving different types of renal damage.
L’insufficienza renale terminale ha raggiunto ormai proporzioni epidemiche in tutto il mondo e, tutt’oggi, non sono ancora state trovate terapie sostitutive o rigenerative efficaci a lungo termine. Attualmente la terapia dialitica e il trapianto allogenico rimangono le uniche alternative valide da utilizzare in questi pazienti nonostante se ne conoscano i numerosi limiti e complicanze. Recenti dati epidemiologici, in America e in Europa, mostrano che l’insufficienza renale colpisce circa l’8% della popolazione. [1] L’aumentata domanda di organi, in aggiunta all’insufficiente disponibilita’ di donatori, sta spingendo sempre piu’ i ricercatori di tutto il mondo a sviluppare nuove alternative terapeutiche per la sostituzione dei reni non funzionanti. [2] La creazione di organi bio-artificiali, attraverso l’utilizzo delle tecniche di ingegneria tissutale, ha finora dimostrato grandi difficolta’ specialmente nel riprodurre quegli organi e tessuti la cui struttura e funzione risultino particolarmente complesse, come nel caso dei reni. Storicamente gli ingegneri tissutali che si sono cimentati in questo campo hanno potuto utilizzare esclusivamente linee cellulari adulte dando origine a costrutti bidimensionali caratterizzati da limitata funzione e difficile applicabilita’ in vivo. [3] Nell’ultima dacade le cellule staminali stanno ricevendo sempre maggiore attenzione scientifica grazie al loro crescente impiego nella medicina rigenerativa per la ricostruzione e rigenerazione di tessuti bio-artificiali ed organi. Le cellule Staminali Embrionali (SE), derivate dalla blastocisti, hanno come caratteristiche peculiari il fatto che si replichino ampliamente e che siano capaci di formare aggregati (corpi embrioidi) che possono dar luogo ad una varietà di cellule specializzate come, ad esempio, cellule neurali, cardiache e pancreatiche. [3, 4] Il reclutamento di questo tipo di cellule staminali, tuttavia, comporta la distruzione di embrioni umani creando spinosi problemi etici e morali che portano, in molti Paesi, a vietarne l’utilizzo e il progresso scientifico. Per evitare questo tipo di controversie ricercatori di varie discipline hanno identificato potenziali fonti di cellule staminali alternative. [4, 5] E’ ormai ben noto che in molti tessuti adulti esistono cellule progenitrici con il compito di rigenerare o riparare l'organo a seguito dei fisiologici processi di senescenza o in caso di danno. [6, 7] Ci sono sempre piu’ evidenze che questi progenitori d’organo abbiano caratteristiche di plasticità piu’ elevate di quanto si pensasse originariamente. Parallelamente molti ricercatori credono che la rigenerazione di organi adulti derivi principalmente dalla mobilizzazione di cellule staminali provenienti dal midollo osseo. E’ stato dimostrato che cellule staminali del midollo osseo possono attraversare la barriera endolteliale e dar luogo a differenti linee cellulari differenziate, trasformando cellule circolanti in fegato, cervello, pancreas, pelle, intestino e anche rene. [27, 29] Il liquido amniotico e’stato usato per anni come uno strumento sicuro e valido per la ricerca di malattie genetiche e congenite del feto. Tuttavia, il liquido amniotico contiene un grande numero di cellule progenitrici che posono avere un importante ruolo nelle applicazioni della bioingegneria tissutale. Streubel et al. [8] hanno riportato l’utilizzo di cellule non emopoietiche per la conversione di amniociti in miociti. Recentemente una popolazione di cellule staminali c-Kit+, isolate nel liquido amniotico umano e murino, e’ stata caratterizzata e differenziata in tessuti originati dai tre foglietti embrionali: muscolare, neuronale, adipocitario, epatico, osseo ed endoteliale [9] Nel laboratorio diretto dal dr. R.E. De Filippo, Assistant Professor presso il Childrens Hospital di Los Angeles, abbiamo ampiamente studiato e utilizzato questa nuova popolazione di cellule staminali derivate dal liquido amniotico focalizzando le nostre ricerche sul loro utilizzo nella rigenerazione renale. Abbiamo dimostrato che questa popolazione totipotente di cellule mesenchimali e’ capace di riprodurre alcune tappe essenziali della nefrogenesi dopo essere state iniettate in reni embrionici. Tuttavia, le cellule staminali da liquido amniotico rapresentano meno dell’1% dell’intera popolazione cellulare e forse esistono altri progenitori cellulari, nel liquido stesso, gia’ orientati e piu’ proni alla differenziazione di particolari linee cellulari renali che possano essere utilizzate per gli stessi scopi rigenerativi ma con risultati migliori. Il volume e la composizione del liquido amniotico cambia durante la gravidanza e dall’ottava settimana di gestazione i reni fetali iniziano a produrre liquido che rapidamente aumenta di volume durante il secondo trimestre. [10] Il contatto tra il liquido amniotico e i diversi tessuti fetali sembra giustificare la presenza dei differenti tipi cellulari disciolti nel liquido stesso. La presenza di cellule mature derivanti dai tre foglietti germinali e’ stata gia’ dimostrata in passato come pure la presenza di progenitori cellulari di origine mesenchimale ed emopoietica prima della 12ma settimana gestazionale nell’uomo. [11,12,13] Cellule esprimenti proteine e markers genetici tipici di tessuti diversi come cervello, cuore, e pancreas sono state ritrovate nel liquido amniotico ma ulteriori indagini sono necessarie per completare la caratterizzazione dei diversi tipi cellulari presenti alle diverse eta’ gestazionali. [14, 15, 16] Lo sviluppo renale e’ un complesso processo di attivazione genica, interazioni cellulari ed extracellulari che devono aver luogo secondo un ordine spazio-temporale preciso e nella quantita’ adeguata. Durante l’embriogenesi, il rene metanefrico origina dall’invasione da parte della gemma ureterale, derivata dal dotto epiteliale di Wolffian, nel mesenchima metanefrico. [17] La gemma ureterale inizia la sua arborizzazione all’interno del mesenchima e portera’ alla formazione dell’intero sistema escretore, dall’uretere ai dotti collettori, mentre il mesenchima metanefrico dara’ luogo alle strutture epiteliali costituenti i nefroni (dal tubulo distale alla capsula di Bowman). CD-24 e Caderina 11 sono due markers di superficie che vengono usati per identificare cellule staminali ancora indifferenziate ma presenti nel mesenchima metanefrico prima di ricevere l’induzione da parte della gemma ureterale. [18] In aggiunta, altri markers di superficie che identificano una sottopopolazione di cellule appartenenti al mesenchima metanefrico nei vari stadi dell’induzione verso la nefrogenesi sono stati recentemente descritti in letteratura: Caderine E, PDGFRα, PDGFRβ, e NGFR ad alta affinita’. [19] Cellule Staminali derivate da liquido amniotico e differenziazione renale in vitro e in vivo Negli ultimi sette anni il gruppo di ricerca di cui ho fatto parte per due anni negli Stati Uniti (University of Southern California - Childrens Hospital Los Angeles) sta studiando una popolazione di cellule staminali ricavate da liquido amniotico (Amniotic Fluid Stem Cells, AFSC), umano e murino. Caratterictiche peculiari di questa popolazione cellulare sono: l’espressione di geni e marcatori di superficie comuni a cellule staminali di origine embrionale e mesenchimale; propagazione in vitro senza necessita’ di feeder-layer; mantenimento della lunghezza dei telomeri; capacità di differenziarsi in vitro e in vivo in molti tipi differenti di cellule e tessuti provenienti da tutti e tre i foglietti embrionali. [7] In particolare, negli ultimi 4 anni, il nostro gruppo si e’ concentrato sull’utilizzo di questa particolare popolazione di cellule staminali derivate da liquido amniotico nella rigenerazione renale in vitro e in vivo. [20, 21] Brevemente, siamo stati in grado di dimostrare, basandoci su un sistema in vitro, come le hAFSC abbiano la capacità di differenziarsi in parenchima renale dopo iniezione diretta in reni embrionici (12.5-16 giorni di gestazione) coltivati in vitro fino a 10 giorni. Le cellule staminali da liquido amniotico erano state precedentemente transfettate con il gene codificante una proteina fluorescente verde (GFP) e un secondo gene codificante per il Lac-Z. Mediante queste transfezioni siamo stati in grado di distinguere le cellule iniettate e dopo aver coltivato gli organi, anche a lungo termine (10 giorni), e’ stato possibile dimostrare la loro integrazione ed assimilazione nelle differenti tappe dello sviluppo renale. Analisi istologica dei reni iniettati con le staminali ha rivelato quanto questa popolazione di cellule sia capace di contribuire alle strutture primordiali del rene a partire dalla vescicola renale fino alle ultime fasi della nefrogenesi (tubuli e glomeruli). Mediante RT-PCR abbiamo quindi dimostrato la neoespressione, da parte delle AFSC iniettate, di geni attivi nelle diverse fasi dello sviluppo embrionale del nefrone. [20] Dopo aver dimostrato questa abilità di integrazione nel tessuto renale in via di sviluppo e la compartecipazione a tutte le tappe utili alla formazione del nefrone maturo in vitro, la nostra idea e’ stata quella di procedere all’applicazione in vivo delle cellule staminali da liquido amniotico. L’obiettivo e’ stato quello di dimostrare la loro reale capacità di sopravvivere, replicarsi ed integrarsi attivamente nei reni danneggiati di un modello di topo immunodepresso. Cellule staminali da liquido amniotico di topo (mouse Amniotic Fluid Stem Cells, mAFSC), esprimenti Lac-z e Luciferasi come marcatori, sono quindi state iniettate per via endovenosa (vena della coda) in un modello di topi immunodepressi con tubulonecrosi acuta. Il nostro ultimo obiettivo e’ stato quello di dimostrare se le cellule staminali venissero utilizzate dai reni danneggiati per riparare il danno e quindi fossero in grado di velocizzare la ripresa funzionale dell’organo. I risultati di tali esperimenti hanno dimostrato che le AFSC hanno una buona capacita’, anche in vivo, di integrarsi e partecipare attivamente alla riparazione del danno. Esse hanno iniziato ad esprimere GDNF, un fattore di trascrizione precoce presente nello sviluppo renale e in particolare nella formazione tubulare e glomerulare, e diversi altri markers tubulari quali Acquaporina-2, Agglutinina P, Agglutinina DB. Dagli esperimenti in vivo e’ quindi emerso che la popolazione di cellule staminali totipotenti, derivata da liquido amniotico (hAFSC), e’ capace di differenziarsi in diversi tipi cellulari appartenenti sia a strutture glomerulari (capsula di Bowman) che tubulari (tubulo distale e prossimale) senza dimostrare una chiara specificita’ per una delle due strutture. [9] In accordo con recenti pubblicazioni, abbiamo dimostrato un effetto immuno-modulartorio delle cellule staminali. Lo studio approfondito delle citochine, endogene ed esogene (prodotte dalle hAFSC iniettate), e il loro effetto nel migliorare la porzione infiammatoria del danno renale sono il passo successivo delle nostre ricerche. Un limite potenziale all’utilizzo terapeutico di questa popolazione cellulare totipotente risiede nel fatto che la maggior parte delle malattie renali che portano ad insufficienza renale terminale, colpiscono primariamente le strutture tubulari o quelle glomerulari, ma difficilmente entrambe contemporaneamente. Utilizzando dunque cellule staminali troppo indifferenziate, e quindi totipotenti, si rischierebbe di perdere efficacia terapeutica a causa del fatto che esse riceverebbero troppi segnali contemporaneamente in senso differenziativo e sarebbero indotte a seguire petterns riparativi non mirati e meno efficaci nella riparazione del danno principale. Se infatti avessimo bisogno di trattare selettivamente un danno tubulare piuttosto che uno glomerulare, l’utilizzo di cellule staminali totipotenti non sarebbe cosi’ ottimale come invece l’utilizzo di progenitori tubulo specifici opportunamente espansi ed eventualmente modificati. Questo concetto insieme al fatto che il liquido amniotico e’ composto da differenti popolazioni cellulari ha spinto a considerare la possibilita’ che ci possano essere linee cellulari maggiormente orientate in senso renale (progenitori organo specifici) che possano essere utilizzate in modo piu’ vantaggioso per la rigenerazione di strutture renali specifiche (id. cellule tubulari prossimali o distali, podociti, cellule mesangiali, cellule endoteliali e altro) Caratterizzazione cellulare del liquido amniotico e ricerca di progenitori renali specifici o gia’ parzialmente differenziati L’ultima parte della tesi si e’ concentrata nello studiare ed identificare le varie popolazioni cellulari presenti nel liquido amniotico a diverse settimane di gestazione. I campioni, di eta’ compresa tra le 15 e le 20 settimane di gestazione, sono stati ottenuti tramite amniocentesi, tecnica usata per studiare il cariotipo del feto durante lo sviluppo. Sono stati valutati differenti terreni di coltura, indagando proliferazione e conservazione della morfologia nei campioni ottenuti. L’analisi e la caratterizzazione della popolazione totale presente nel liquido amniotico e’ stata effettuata utilizzando RT-PCR, Real Time PCR e Western Blotting, analizzando l’espressione specifica di geni che sono coinvolti nel mantenimento della pluripotenzialita’, geni che identificano specificatamente i tre foglietti embrionali ed infine geni che identificano progenitori organo-specifici. Sono state inoltre identificate popolazioni specifiche renali, tramite immunoseparazione con biglie magnetiche (MASC). L’espressione di marcatori per i foglietti embrionali endoderma e mesoderma e’ piu’ alta in campioni piu’ giovani rispetto a campioni con tempo di gestazione maggiore mentre, per l’ectoderma, rimane pressoche’ invariata nel tempo. La presenza di cellule pluripotenti e’ costante cosi’ come le cellule staminali mesenchimali mentre le cellule progenitrici ematopoietiche, investigate tramite CD34, fanno la loro comparsa successivamente alle 17 settimane di gestazione. La presenza di progenitori tessuto specifici già “committed” e’ evidente nei campioni di gestazione più avanzata sia per quantitita’ che per specificità dell’organo preso in esame. E’ stata approfondita l’analisi di cellule progenitrici renali, utilizzando un ampio pannello di marcatori che identificano sia la componente tubulare che quella glomerulare del nefrone, struttura fondamentale per la filtrazione renale. I risultati ottenuti confermano la presenza di cellule progenitrici renali dopo le 18 settimane di gestazione. E’ stata identifica e studiata una popolazione esprimente CD24 e Caderin 11 isolata da campioni di liquido amniotico di 18 o piu’ settimane. CD24 e OB-cadehrin sono stati identificati nel topo come co-espressi in vivo nel mesenchima metanefrico. Dal mesenchima metanefrico ha origine il nefrone ed e’ una delle due strutture embrionali fondamentali per lo sviluppo del rene. Da questa popolazione principale sono state ottenute 4 nuove sottopopolazioni che identificano sottocompartimenti del glomerulo, come per esempio le cellule corticali stromogeniche (tramite selezione per la Tyrosin Kinase, TrKA), i podociti (selezionati per la Nefrina), le cellule del mesangio (con selezione positiva per PDGFR Alpha) e le cellule in transizione mesenchima-epitelio (con selezione per la Cadherina-E). Tramite PCR e Real Time PCR e’ stata dimostrata la forte specificita’ di ogni singola linea cellulare. E’ necessario uno studio approfondito che preveda per le AKPC differenziazioni in vitro ed in vivo, utilizzando fattori di crescita nefro-specifici e diversi modelli di danno renale acuto e cronico, in modo tale da confermare la loro possibile completa differenziazione in cellule renali mature. Un approfondimento sul meccanismo d’azione e sulle migliori tempisitiche di somministrazione, infine, sono i punti fondamentali da chiarire per comprendere il meccanismo d’azione delle hAFSC in vivo. Queste ricerche sono una base fondamentale per future applicazioni cliniche in pazienti che soffrono di nefropatie acute e croniche

To see if aggressive diuresis in first twenty four hours is associated with a comparable number of total days in the hospital as compared to non-aggressive diuresis. In this retrospective cohort study, we compared the length of hospital stay of consecutive patients admitted in one year based on their diuresis during the first twenty-four hours of hospitalization: aggressive diuresis (group 1) i.e. > 2400mL versus non-aggressive diuresis (group 2) i.e. ≤ 2400mL urine output. Patients were excluded if in cardiogenic shock, had creatinine level above 3 mg/dL on admission, or on dialysis. A total of 194 patients were enrolled (29 in group 1 and 165 in group 2 respectively). The Kaplan-Meier estimate of the median cumulative proportion of patients still hospitalized for the group 1 was 4 days and in group 2 was 5 days (log-rank test; P=0.67). In univariate analysis, Cox PH regression showed unadjusted hazard rate of discharge from hospital was slightly higher in group 1 than group 2 but was statistically non-significant (HR=1.08; P=0.70). In multivariate Cox model analysis, creatinine at the time of admission when greater than 1.6mg/dL (P=0.75), LVEF (P= 0.14), total twenty-four hours dose of intravenous Furosemide given (P=0.98) and interaction between Furosemide dose and Creatinine level (P=0.79) were not significant predictor of hospital discharge. Adjusted hazard rate for discharge from hospital was 12% higher in group 1 than group 2 but still statistically non-significant (HR=1.12; P=0.60). Since the length of hospital stay is similar between two groups, we suggest the goal of diuresis to be less than 2400mL in first twenty-four hours to prevent excessive dehydration.

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The aim of the present study was to investigate the effects of the use of the anti-inflammatory protein annexin 1 (Anx-A1), which is found in most cells. It is characterized by its ability in binding to calcium and phospholipids, conferring protection against the initial effects of ischemia-reperfusion injury. Right nephrectomy was performed on 48 adult males Wistar rat, with sizes ranging between 250-300 g, maintained on a diet normosodic , normoprotein and with water ad libitum. The animals was divided into 3 groups: Annexin-1/Ischemia (Anx-A1-I/R) (n=16), vehicle (PBS40)-Ischemia (Vehicle-I/R) (n=16) and Sham Group (n=16). The endovenous administration of Anx-A1 was made 30 minutes before ischemia of the left renal artery. The animals of each group were divided and studied at 2 and 7 days post-reperfusion, in respect to the glomerular, tubular and renal structure functions. The results showed that there was a reduction in the glomerular filtration rate (GFR) in the Vehicle-I/R Groups at 2 and 7 days post-reperfusion (0.42 ± 0.02 mL/min-100g and 0.48 ± 0.05 mL/min-100g, respectively). There was a significantly greater filtration rate in the Anx-A1-I/R Groups compared to the Vehicle-I/R Groups (0.86 ± 0.05 mL/min-100g and 0.73 ± 0.04 mL/min-100g, respectively). A significant difference between the Anx-A1-I/R and Sham Groups (p-value < 0.01) was also observed (7days). The fractional sodium excretion (FeNa) was significantly higher in the Vehicle-I/R Groups when compared to the Anx-A1-I/R and Sham Groups on the 2nd and 7th post-perfusion days. On the 2nd day of the study, the fractional sodium excretion was 0.17 ± 0.01% for the Anx-A1-I/R, 0.42 ± 0.03% for the Vehicle-I/R and 0.21 ± 0.01% for the Sham groups (p-value < 0.001). On the 7th day, the values were 0.27 ± 0.03%, 0.52 ± 0.03% and 0.29 ± 0.01%, respectively (p-value < 0.001). The potassium excretion fraction (FeK) on the 2nd and 7th post-perfusion days did not differentiate between the Anx-A1-I/R and Sham Groups, but it was significantly higher in the Vehicle-I/R Groups. The urinary-plasmatic osmolality ratio (U/Posm) showed a significant reduction in the Vehicle-I/R Groups after 2 and 7 days when compared with the Anx-A1-I/R and Sham Groups. A histopathologic evaluation of renal cortex samples, taken on the 2nd and 7th post-perfusion days, revealed a significant increase in the intravascular and transmigrated neutrophils in ischemic areas of the Vehicle-I/R Groups. Additionally, high rates of transmigrated neutrophils were identified in the ischemia-reperfusion areas of samples of renal medulla from the Vehicle-I/R Group taken on the 2nd and 7th days. There was a significant reduction of the neutrophil transmigration in samples of renal medulla on the 2nd and 7th post-perfusion days in the Anx-A1-I/R Groups, as well as a lower intravascular neutrophil rate. On the 2nd and 7th post-perfusion days, the Sham Group presented with structures of distal and proximal convoluted tubules and well-preserved brush-border structures in the renal cortex and medulla samples as seen by light microscopy. Similar results were evidenced in the Anx-A1-I/R Groups with preserved structures in the tubules, basal membrane and glomeruli. In the Vehicle-IR Groups, numerous monocytes, cellular debris inside proximal convoluted tubules, dilated capillaries and alterations in the basal membrane structure were seen. These results suggest that the administration of annexin-1 thirty minutes before renal ischemia in rat , prevents the transmigration of neutrophils and confers protection against the initial effects of ischemia-reperfusion injury, as well as providing protection to the glomerular, tubular and renal structure functions.
O presente estudo objetivou investigar os efeitos do uso da anexina 1 (Anx-A1), considerada proteína antiinflamatória e que está presente na maioria das células. Caracteriza-se pela sua habilidade em ligar-se ao cálcio e fosfolipídeos, conferindo proteção contra os efeitos iniciais da lesão por isquemia e reperfusão. Realizou-se nefrectomia à direita em 48 ratos (Wistar-adultos-machos), pesando entre 250-300 gramas, mantidos com dieta normosódica , normoprotéica e água ad libitum. Os animais foram divididos em 3 grupos: Anexina 1-Isquemia (Anx-A1-I/R) (n=16), Veículo(PBS-40)-Isquemia (Veic-I/R) (n=16) e grupo Sham (n=16). A administração de anexina1 endovenosa foi realizada 30 minutos antes do clampeamento da artéria renal esquerda. Após reperfusão, os animais de cada grupo foram divididos e estudados com 2 e 7 dias, quanto às funções glomerulares , tubulares e à estrutura renal. Os resultados mostraram que houve redução da taxa de filtração glomerular (RFG) nos grupos veículo-I/R com 2 e 7 dias de experimento (0,42 ± 0,02 ml-min-100g e 0,48 ± 0,05 ml-min-100g, respectivamente) e verificamos aumento significativo da taxa de filtração glomerular nos grupos Anx-A1-I/R comparados aos grupos veículo-I/R (0,86 ± 0,05ml-min-100g e 0,73 ± 0,04ml-min-100g, respectivamente). Observou-se diferença significativa entre os grupos Anx-A1-I/R e Sham com 7 dias (p<0,01). A excreção fracional de sódio (FeNa) apresentou-se significantemente aumentada nos grupos veículo-I/R, comparada aos grupos Anx-A1-I/R e Sham nos 2º e 7º dias de experimento; apresentando assim no 2º dia de estudo,Anx-A1-I/R (0,17 ± 0,01%), Veic-I/R (0,42 ± 0,03%) e Sham (0,21 ± 0,01%) (p<0,001); e no 7º dia, Anx-A1-I/R (0,27 ± 0,03%), Veic-I/R (0,52 ± 0,03%) e Sham (0,29 ± 0,01%) (p<0,001). A fração de excreção de potássio (FeK) com 2 e 7 dias de experimento não diferiram entre os grupos Anx-A1-I/R e Sham, mas a FeK aumentou significativamente nos grupos Veic-IR. A razão das osmolalidades urinário-plasmáticas (U/Posm) mostraram uma redução importante nos grupos Veic-I/R em experimentos com 2 e 7 dias, comparados aos grupos Anx-A1-I/R e Sham. A avaliação histopatológica revelou aumento significativo de neutrófilos intravasculares e transmigrados, em áreas isquêmicas dos grupos Veic-I/R, de amostras avaliadas da porção do córtex renal com 2 e 7 dias. Verificaram-se altas taxas de transmigração de neutrófilos nas áreas de isquemia-reperfusão nos grupos Veic-I/R com 2 e 7 dias, em amostras avaliadas de medula renal. Houve significativa redução do extravasamento de neutrófilos em análise quantitativa, nas amostras de medula renal com 2 e 7 dias de estudo, nos grupos anexina 1-I/R, bem como menor taxa de neutrófilos no espaço intravascular. À microscopia de luz, verificou-se que, em amostras de córtex e medula renal, com 2 e 7 dias, o grupo Sham apresentou estruturas dos túbulos contorcidos proximais, distais e borda em escova bem preservados. Notou-se resultados semelhantes nos grupos de anexina1-I/R, com estruturas preservadas nos túbulos, membrana basal e glomérulos. Nos grupos Veic-I/R, verificou-se a presença de debris celulares no interior de túbulos contorcidos proximais, capilares dilatados e alterações na estrutura da membrana basal. Estes resultados sugerem que a administração da anexina1, trinta minutos antes da isquemia renal em ratos, previne a transmigração de neutrófilos e confere proteção contra os efeitos iniciais da lesão por isquemia e reperfusão, bem como proteção das funções glomerulares, tubulares e da estrutura renal.

BACKGROUND: Early and appropriate antibiotic administration has been shown to be the most effective intervention for reducing mortality in critically ill patients with septic shock and multiple organ dysfunction syndrome (MODS). However, despite its relevance, antibiotic dosing in those patients with MODS including acute kidney injury (AKI) that require continuous renal replacement therapy (CRRT) still represents a major challenge for clinicians. In our environment, the broad[spectrum beta[lactams meropenem and piperacillin (in combination with tazobactam) are the antibiotics most frequently prescribed to these patients with very high levels of sickness severity. The impact of septic shock, AKI and CRRT on these antibiotics’ dose requirements is vital, as medical interventions and the disease itself are likely to produce significant variations in their pharmacokinetics (PK), which may lead to alterations in drug concentrations over time and hence compromise the achievement of drug concentrations within the therapeutic range. However, it is still very complex to individualize piperacillin and meropenem dosing in patients with septic shock and AKI necessitating CRRT. HYPOTHESIS: Meropenem and piperacillin dosing is not optimal in critically ill patients with septic shock and AKI requiring CRRT due to disease and medical[driven variations in antibiotic PK and, therefore, in dose requirements, which may lead to failure in the achievement of therapeutic concentrations. AIMS: 1. To evaluate the suitability of current meropenem and piperacillin dosing recommendations in critically ill patients with septic shock and AKI necessitating CRRT; 2. To identify the sources of variability that compromise optimal drug dosing in this patient population; and 3. To develop new recommendations that allow dose individualization considering these variability sources. METHODS: Three studies have been developed under the study hypothesis and aims. Study 1: Literature review. A systematic literature review and critical evaluation of the available evidence on meropenem and piperacillin dosing in critically ill patients with septic shock and AKI necessitating CRRT has been performed. Studies 2 and 3: Characterization of the PK of meropenem and piperacillin in critically ill patients with septic shock and AKI necessitating CRRT. Two observational, prospective, multicenter, open[label pharmacokinetic studies have been performed in the Intensive Care Units from three Spanish tertiary hospitals. Thirty patients with septic shock and CRRT receiving meropenem and 19 patients receiving piperacillin have been enrolled. Two population PK models have been developed and subsequently validated with data from these patients, and Monte Carlo simulations have been undertaken using NONMEM v.7.3®. RESULTS: The main finding of study 1 is that present “oneTsizeTfitsTall” dosing recommendations for meropenem and piperacillin in critically ill patients with septic shock and AKI requiring CRRT are based on studies with some drawbacks, such as: 1) different sickness severities and levels of renal function, 2) different admission diagnostics (medical versus surgical versus trauma), 3) different clinical managements mainly CRRT settings, 4) heterogeneous PK methodologies, and 5) different PD targets for dosing recommendations. This scenario limits extrapolation of their conclusions to our patient population. Later on, studies 2 and 3 have identified important sources of meropenem and piperacillin PK variability that may assist in dose individualization. For meropenem, the main finding of the population PK analysis is the relationship existing between the 24h urine output and meropenem total clearance (CL). Patients with conserved diuresis (>500mL/24h) exhibit at least a 30% increase in meropenem total CL compared to those patients who are anuric (<100mL/24h), increase that is directly proportional to urine volume. Following Monte Carlo simulations based on this population PK model have shown that for maintaining unbound concentrations of meropenem above the minimum inhibitory concentration (MIC) of the bacteria for a 100% of the dosing interval (100% FuT>MIC), oligoanuric patients (residual diuresis 0[500mL/24h) require 500mg/q8h over 30min for the treatment of susceptible bacteria (MIC<2mg/L), while patients with preserved diuresis (>500 mL/24h) require the same dose over a 3h[infusion. If bacteria with MIC close to the resistance breakpoint (2[4mg/L) are to be treated with meropenem, a dose of 500mg/q6h is necessary: over a 30min[bolus for oligoanuric patients and over a 3h[infusion for patients with preserved diuresis. For the attainment of more conservative PD targets (40% FuT>MIC), 500mg/q8h over a 30min[bolus is sufficient regardless of residual diuresis With regards to piperacillin, the main finding of the population PK analysis is the relationship existing among the type of membrane used for CVVHDF, the patient’s weight and piperacillin total CL; for a body weight of 80kg, piperacillin total CL is doubled when a 1.5m2 AN69 acrylonitrile and sodium methallyl sulfonate copolymer filter pre[ coated with heparin and polyethyleneimine (AN69ST) is used compared to the CL for a 0.9m2 AN69 filter. Subsequent Monte Carlo simulations have shown that for a PD target of 100% FuT>MIC, patients receiving CVVHDF with 1.5m2 AN69ST membranes require doses of 4000mg/q8h for the treatment of bacteria with a susceptibility to piperacillin close to the clinical breakpoint (MIC = 8[16mg/L). In contrast, 2000mg/q8h are sufficient for patients with CVVHDF using 0.9m2AN69 membranes. For the treatment of bacteria with high susceptibility to piperacillin (MIC ≤ 4mg/L) or for the attainment of a more conservative PD target (50% FuT>MIC), 2000mg/q8h are sufficient in all cases. CONCLUSIONS: Due to data heterogeneity, current meropenem and piperacillin dosing recommendations for patients with septic shock and CRRT follow a one[size[fits[all fashion, which often translates into a best[guess dosing at the bedside. In this context, we have shown that identification and consideration of clinical and demographic parameters that influence meropenem and piperacillin PK, such as 24h urine output, patient’s weight and type of CRRT membrane, is advantageous for dose titration. As they are characteristics easy to be measured at the bedside, the implementation of our research findings in the real clinical setting is easy and may be helpful in the complex process of optimization of antibiotic use in the Intensive Care Unit.
L’administració precoç d’antibioteràpia apropiada ha demostrat ser la intervenció més eficaç per reduir la mortalitat en pacients crítics amb xoc sèptic i síndrome de disfunció multiorgànica (SDMO). Malgrat la seva rellevància, però, la dosificació antibiòtica en els pacients amb SDMO incloent insuficiència renal aguda (IRA) que requereixen teràpia continua de suport renal (TCSR) encara representa un repte diari pels professionals de la salut. Al nostre medi, els antibiòtics beta[lactàmics d’ampli espectre meropenem i piperacilelina (en combinació amb tazobactam) són els antibiòtics més prescrits a aquests pacients d’altíssima complexitat i gravetat. L'impacte del xoc sèptic, la IRA i la TCSR en els requeriments de dosis d'aquests fàrmacs és vital, ja que tant la pròpia malaltia com les intervencions mèdiques produeixen alteracions significatives en la seva farmacocinètica (FC), que duen a variacions en els perfils concentració[temps i, conseqüentment, comprometen l'assoliment de concentracions del fàrmac dins del rang terapèutic. No obstant això, individualitzar la dosificació de meropenem i piperacilelina en pacients amb xoc sèptic, IRA i requeriment de TCSR és encara molt complex. HIPÒTESI: La dosificació de meropenem i piperacilelina en pacients crítics amb xoc sèptic i IRA que requereixen TCSR és sub[òptima degut a les variacions en el comportament FC dels fàrmacs produïdes tant per la malaltia com pel maneig mèdic d’aquesta. Aquestes variacions FC poden comprometre l'assoliment de concentracions terapèutiques. OBJECTIUS: 1. Avaluar la idoneïtat de les recomanacions actuals sobre dosificació de meropenem i piperacilelina en pacients crítics amb xoc sèptic i IRA que requereixen TCSR; 2. Identificar les fonts de variabilitat que comprometen l’exposició òptima a aquests antibiòtics en la nostra població de pacients; i 3. Desenvolupar noves recomanacions per individualitzar la dosificació d’aquests antibiòtics tenint en compte aquestes fonts de variabilitat. METODOLOGIA: En base a la hipòtesi i els objectius, s’han desenvolupat els tres estudis següents: Estudi 1: Revisió de la literatura. S’ha realitzat una revisió sistemàtica i avaluació crítica de l'evidència disponible sobre la dosificació de meropenem i piperacilelina en pacients crítics amb xoc sèptic, IRA i requeriment de TCSR. Estudis 2 i 3: Caracterització de la FC de meropenem i piperacilelina en pacients crítics amb xoc sèptic i IRA que requereixen TCSR. S’han realitzat dos estudis farmacocinètics multicèntrics, oberts, prospectius observacionals, a les Unitats de Medicina Intensiva de tres hospitals espanyols de tercer nivell. S’han inclòs a l’estudi 30 pacients amb xoc sèptic, IRA i TCSR que rebien meropenem i 19 pacients que rebien piperacilelina. Amb les dades procedents d’aquests pacients, s’han desenvolupat i validat dos models FC poblacionals, a partir dels quals s’han realitzat simulacions de Monte Carlo de diferents esquemes terapèutics (mitjançant el software NONMEM v.7.3®). RESULTATS: La principal troballa de l'estudi 1 és que les recomanacions actuals de dosificació de meropenem i piperacilelina en pacients crítics amb xoc sèptic i IRA que requereixen TCSR es basen en estudis amb algunes limitacions, com ara: 1) diferents nivells de gravetat de la malaltia i de disfunció renal, 2) diferents diagnòstics d’ingrés (mèdic versus quirúrgic versus trauma), 3) diferents maneigs clínics, principalment referent a les característiques de la TCSR, 4) metodologies heterogènies d’anàlisi FC, i 5) diferents objectius farmacodinàmics (FD) en base als quals es fan les recomanacions de dosificació. Això compromet l'extrapolació dels resultats d’aquests estudis a la nostra població de pacients. Posteriorment, els estudis 2 i 3 han identificat importants fonts de variabilitat en la FC de meropenem i piperacilelina, que si es consideren en el moment de la dosificació poden ser útils per individualitzar el tractament antibiòtic. Pel que fa a meropenem, la principal conclusió de l'anàlisi FC poblacional és la relació existent entre la diüresi acumulada de 24h i l’aclariment total de meropenem (CL). Els pacients amb diüresi conservada (>500ml/24h) presenten un increment d’almenys el 30% sobre el CL total de meropenem en comparació amb aquells pacients anúrics (<100mL/24h), sent aquest augment en el CL del fàrmac directament proporcional al volum d'orina. Posteriorment, les simulacions de Monte Carlo basades en aquest model FC poblacional han demostrat que per tal de mantenir les concentracions de meropenem per damunt de la concentració mínima inhibitòria (CMI) dels bacteris durant un 100% de l'interval de dosificació (100% FuT>CMI), els pacients oligo[anúrics (diüresi residual de 0[500mL/24h) requereixen 500mg/q8h administrats en un bolus de 30 minuts per al tractament de microorganismes susceptibles (CMI <2 mg/L), mentre que els pacients amb diüresi conservada (>500mL/24h) requereixen la mateixa dosi administrada mitjançant una perfusió de 3h. Pel tractament de microorganismes amb una CMI propera al límit de susceptibilitat (2[ 4mg/L) és necessària una dosi de 500mg/q6h: administrada en un bolus de 30 minuts de en pacients oligo[anúrics i mitjançant una perfusió de 3h en pacients amb una diüresi conservada. Si s’escull un objectiu FD més conservador, (40% FuT>CMI), una dosi de 500mg/q8h administrada en un bolus de 30 minuts és suficient amb independència de la diüresi residual. Pel que fa a la piperacilelina, la principal conclusió de l'anàlisi FC poblacional és la relació existent entre el tipus de membrana utilitzada per la TCSR, el pes del pacient i el CL total de piperacilelina; per a un pes de 80 kg, el CL total de piperacilelina es duplica quan es fa servir una membrana d’1,5m2 de copolímer d’acrilonitril i sulfat sòdic de metalelil amb un recobriment d’heparina i polietilenimina (AN69ST) en comparació amb el CL total observat quan es fa servir un filtre AN69 convencional de 0,9m2. Posteriors simulacions de Monte Carlo han demostrat que per a un objectiu FD de 100% FuT>CMI, els pacients que reben TCSR amb membranes AN69ST d’1,5m2 requereixen dosis de 4000mg/q8h per al tractament de microorganismes amb CMI properes al límit de susceptibilitat (CMI = 8[ 16mg/L). Per contra, 2000mg/q8h són suficients per als pacients que reben TCSR amb membranes AN69 de 0,9 m2. Per al tractament de soques d’alta susceptibilitat a la piperacilelina (CMI ≤ 4mg/L), o per l’assoliment d'un objectiu FD més conservador (50% FuT>CMI), 2000mg/q8h són suficients en tots els casos.

Injúria renal aguda (IRA) é doença de elevada incidência, associada a altas taxas de morbimortalidade. Sepse, pós-operatório de grandes cirurgias e baixo débito cardíaco são as principais causas de IRA em todo o mundo. Na maioria destas situações, expansão volêmica é parte do manejo preventivo e terapêutico da IRA. Contudo, a manutenção de uma estratégia de infusão liberal de fluidos pode causar balanço hídrico positivo (BH+), que tem sido associado a desfechos desfavoráveis em pacientes criticamente enfermos. BH+ frequentemente ocorre nestes pacientes que recebem grandes infusões de volume, mesmo que apresentem volume urinário considerado satisfatório ou acima de 0,5ml/kg/h. Nesta situação, se não houver elevação da creatinina sérica, não será feito o diagnóstico de IRA pelos critérios do Kidney Disease Improving Global Outcome (KDIGO), ainda que haja claro déficit na eliminação da sobrecarga hidrossalina. Este estudo observacional prospectivo, com controle pareado por dias de exposição ao BH+ avaliou a associação entre BH+ e diagnóstico subsequente de IRA (pelos critérios do KDIGO) e mortalidade em 233 pacientes admitidos em uma unidade de terapia intensiva (UTI) geral. Observamos por análise de regressão logística que cada 100 ml de aumento no BH se associou a elevação de 4% na chance de desenvolver IRA (OR 1,04; IC 95% 1,01 a 1,08). Comparado ao primeiro quartil de BH médio, o quarto quartil de BH médio (BH > +1793 ml/dia) se associou a chance 3,12 vezes maior de desenvolver IRA (OR 3,12; IC 95% 1,13 a 8,65). Comparado ao BH de zero até +1500 ml/dia, o BH médio > +1500 ml/dia se associou a chance 3,4 vezes maior de desenvolver IRA, (OR 3,4; IC 95% 1,56 a 7,48). Um modelo de efeito fixo mostrou que BH+ estava presente pelo menos seis dias antes do diagnóstico de IRA pelos critérios do KDIGO. Para avaliar o desfecho óbito, consideramos o BH durante toda internação na UTI. Observamos que cada 100 ml de aumento no BH se associou a incremento de 7% na mortalidade (OR 1,07; IC 95% 1,02 a 1,12). Comparado ao primeiro quartil, o quarto quartil de BH médio (BH > +1652 ml/dia) se associou a chance 2,8 vezes maior de evoluir para óbito (OR 2,8; IC 95% 1,04 a 7,66). Comparado aos pacientes com BH de zero a +1500 ml/dia, os pacientes com média de BH > +1500 ml/dia apresentavam chance 3,8 vezes maior de evolução para óbito (OR 3,8; IC 95% 1,55 a 9,16). Em conclusão, BH+ como variável contínua, em quartis ou utilizando ponto de corte maior do que +1500 ml/dia se associou de maneira independente a maior chance de desenvolvimento subsequente de IRA e evolução para óbito em pacientes criticamente enfermos. No presente trabalho, o BH + foi biomarcador precoce de IRA. Estes achados sugerem que BH+ deve ser incluído nos critérios de definição de IRA, ao lado da creatinina e diurese
Acute kidney injury (AKI) is a disease with high incidence, which is associated with high morbidity and mortality rates. Sepsis, major surgery and low cardiac output are the main causes of AKI worldwide. In the majority of these situations, volume expansion is part of both prevention and therapeutic management of AKI. However, maintaining liberal fluid infusion strategy can cause fluid overload and it is associated to poor outcomes in critically ill patients. Positive fluids balance (FB) frequently occurs in these patients receiving high volume infusion, even if the urinary output is adequate (above 0.5ml/kg/h). In this situation, if there is no serum creatinine (SCr) increase, AKI will not be diagnosed by current Kidney Disease Improving Global Outcome (KDIGO) criteria, even with a clear kidney inability to eliminate the body excess of fluid. This prospective, paired control, cohort study aimed to evaluate the association between positive FB and subsequent development of AKI by KDIGO criteria and mortality in 233 critically ill adults. By multiple logistic regression, we showed that each 100 ml increase in FB was independently associated to a 4% increase in the chances for developing subsequent AKI (OR 1.04; 95% CI 1.01 to 1.08). When compared to the first quartile, the fourth FB quartile (FB > +1793ml/day) was associated with a 3.12 times greater chance of developing AKI (OR 3.12; 95% CI 1.13 to 8.65). Compared to FB zero to 1,500ml/24h, the mean FB above +1,500 ml/24h was associated with an OR of 3.4 for AKI (OR 3.4; 95% CI 1.56 to 7.48). A mixed effect model demonstrated that a positive FB predicted AKI development defined by KDIGO criteria within 6 days. To assess the outcome mortality, we evaluated the mean FB during the whole ICU hospitalization. Each 100 ml increase in FB was associated to a 7% increase in the chances for death (OR 1.07; 95% CI 1.02 to 1.12). Compared to the first quartile, patients in the fourth FB quartile (FB > +1652 ml/day) showed an OR of 2.8 for death (OR 2.8; 95% CI 1.04 to 7.66). Mean FB above +1,500 ml/24h was associated with an OR of 3.8 for death, as compared to FB zero to 1,500ml/24h (OR 3.8; 95% CI 1.55 to 9.16). In conclusion, positive FB, as continuum variable, as quartiles and as absolute thresholds, was independently associated with subsequent AKI development and death in critically ill patients. In this study, the positive FB was early biomarker of AKI. These findings suggest that positive FB should be included in the criteria for AKI in addition to serum creatinine and urine output

En réanimation, il n’existe pas de gold standard pour estimer le débit de filtration glomérulaire (DFG). Nous avons mesuré la clairance du iohexol chez 20 patients en insuffisance circulatoire aiguë (injection de 5 mL de iohexol et cinétique riche sur 24h). Les clairances urinaire et plasmatique étaient équivalentes ; la clairance plasmatique n’était pas influencée par le remplissage. Nous avons étudié la distribution de la clairance du iohexol chez 85 patients en insuffisance circulatoire aiguë. Quarante-et-un patients (48%) avaient un DFG < 30 mL.min-1, 29 (34%) entre 30 et 60mL.min-1, 10 (12%) entre 60 et 90mL.min-1, 4 (5%) entre 90 et 130 mL.min-1 et 1 (1%) > 130 mL.min-1. Nous avons mesuré les biomarqueurs lésionnels [TIMP-2].[IGFBP-7] juste avant, 6h et 24 h après un scanner injecté en réanimation; il n’y a pas eu d’augmentation significative des biomarqueurs, confortant l’hypothèse d’une toxicité négligeable des produits de contraste iodés en réanimation. En conclusion, le iohexol peut être considéré comme un gold standard pour l’estimation du DFG chez des patients en insuffisance circulatoire aiguë en termes de faisabilité, fiabilité et sécurité
There is no gold standard for glomerular filtration rate (GFR) estimation in intensive care unit. We measured iohexol clearance in 20 patients experiencing acute circulatory failure (5 mL iohexol bolus, urine and blood-sample collections over 24h). Urinary and plasma clearances were equivalent; rapid fluid infusion did not influence plasma clearance. We studied iohexol clearance repartition in 85 patients experiencing acute circulatory failure. Forty-one (48%) had a GFR < 30 mL.min-1, 29 (34%) between 30 and 60mL.min-1, 10 (12%) between 60 and 90mL.min-1, 4 (5%) between 90 and 130 mL.min-1 and 1 (1%) > 130 mL.min-1. We measured lesion biomarkers [TIMP-2].[IGFBP-7], before, 6h and 24h after an injected computed tomography scan; there was no significant raise in the biomarkers. This result supports the hypothesis that contrast media are armless in intensive care units. To conclude, iohexol can be considered as a gold standard for GFR estimation in acute-circulatory-failure patients regarding feasibility, reliability and safety

Malaria remains one of the world's major health problems, especially in developing countries. A better understanding of the pathology and pathophysiology of severe malaria is key to develop new treatments. Different approaches have been used in malaria research including the in vitro co-culture models with endothelial cells and both murine and simian animal models. However these are open to controversy due to disagreement on their representativeness of human disease. Using human post-mortem tissue in malaria research is another important approach but is practically challenging, limiting the availability of post mortem samples from malaria patients. The work in this thesis had two main themes. First I examined the role of the endothelial signalling Angiopoetin-Tie-2 receptor pathway in malaria. Ang-2 has been shown to be a significant biomarker of severe and fatal malaria. I examined the tissue specific expression of proteins from this pathway in post-mortem brain tissues from fatal malaria cases, but found no difference between cerebral malaria and non-cerebral malaria cases. Ang-2 correlated with the severity of malaria in these patients. An attempt to examine the interaction of hypoxia and the Ang-Tie-2 pathway in vitro using a co-culture model of human brain endothelial cells was unsuccessful due to contamination of the cell line. The second part of the thesis aimed to utilise molecular pathology techniques including miRNA and whole-genome microarrays. I have shown for the first time that these can be successfully applied to human post-mortem tissue in malaria. First I used archival tissues to examine the microRNA signature in the kidney of patients with malaria associated renal failure. Second I optimised a protocol to preserve post mortem tissue for molecular pathology, from an autopsy study in Mozambique. Using the subsequent total mRNA transcriptomic data and bioinformatics analysis this work has expanded our knowledge of differential gene expression and the families of genes which are dysregulated in the brain in response to malaria infection.

Thesis (Ph. D.)--Ohio State University, 2003.
Title from first page of PDF file. Document formatted into pages; contains xiv, 254 p.; also includes graphics Includes bibliographical references. Available online via OhioLINK's ETD Center

La prédiction du devenir du greffon et de sa survie permettrait d’optimiser la prise en charge des patients transplantés. Le suivi des patients transplantés rénaux inclue des mesures répétées de marqueurs longitudinaux tels que la créatinine sérique et l’exposition aux médicaments immunosuppresseurs. L’approche statistique récemment proposée des modèles conjoints permet d’analyser la relation entre un processus longitudinal et la survenue d’un événement clinique. Dans la première partie de ce travail de thèse, nous avons utilisé les modèles conjoints à classes latentes pour étudier l’impact du profil de créatinine sérique au cours des 18 premiers mois post-greffe sur la survie du greffon à long terme. Dans la cohorte étudiée, trois groupes homogènes caractérisés par une trajectoire spécifique de l’évolution de la créatinine sérique en fonction du temps et un risque d’échec de greffe spécifique ont été identifiés. Les probabilités individuelles de l’échec de greffe pendant les 10 premières années post-transplantation ont été calculées sur la base du modèle conjoint développé. Chez les patients qui n’avaient pas développé d’anticorps anti-HLA spécifiques du donneur, le risque d’échec de greffe en fonction du temps était prédit avec un niveau de performance satisfaisant en termes de spécificité, sensibilité et précision.L’utilité clinique de cet outil devra être évaluée avec une approche dynamique. Dans une seconde partie, les modèles non linéaires à effets mixtes combinés avec l’approche des modèles de mélange a été utilisée pour analyser (i) l’association entre la variabilité de l’exposition au tacrolimus au cours du temps et l’adhésion au traitement rapportée par le patient et (ii) l’impact de cette variabilité d’exposition sur le risque de rejet aigu. Ce modèle a montré un effet significatif de la variabilité de l’exposition au cours du temps du tacrolimus sur la survenu de rejet aigu au-delà de 3 mois post-transplantation. Au contraire, aucune association entre l’adhésion et la variabilité de l’exposition au tacrolimus d’une part, et le risque de rejet aigu d’autre part n’a été observée dans cette étude qui n’incluait que des patients modérément non-adhérents. Ce résultat pose la question de l’impact d’une non adhésion modérée sur le devenir du greffon
Prediction of graft outcome would be useful to optimize patient care. Follow-up of kidneytransplant patients include repeated measurements of longitudinal markers, such as serum creatinine and immunosuppressive drug exposure. Recently proposed joint models areappropriate to analyze relationship between longitudinal processes and time-to-event data. In the first part of present work, we used the approach of joint latent class mixed models tostudy the impact of time-profiles of serum creatinine collected within the first 18 months after kidney transplantation on long-term graft survival. The studied cohort was parted into three homogenous classes with a specific time-evolution of serum creatinine and a specific risk of graft failure. The individual predicted probabilities of graft failure up to 10 years posttransplantation, calculated from this joint model were satisfying in terms of sensitivity, specificity and overall accuracy, for patients who had not developed de novo donor specificanti-HLA antibodies. The clinical usefulness of developed predictive tooI needs to beevaluated with a dynamic approach. In the second part, non-linear mixed effects models witha mixture of distribution for random effects were used to investigate (i) the associationbetween variability over time of tacrolimus exposure and self-reported drug adherence and(ii) the impact of this variability on the acute rejection risk. This model found a significantimpact of tacrolimus time-exposure variability on acute rejection onset beyond 3 months posttransplantation. On the contrary, no association between adherence and (i) variability oftacrolimus time-exposure and (ii) acute rejection was observed in our study which included moderate non-adherent patients only. This result questions the impact of moderate nonadherence on graft outcome

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
A insuficiÃncia renal ocasiona importantes disfunÃÃes gastrintestinais. Entretanto poucos estudos apontam a relaÃÃo entre a insuficiÃncia renal e o funcionamento do trato gastrintestinal. Neste trabalho estudamos o esvaziamento gÃstrico e o trÃnsito gastrintestinal de lÃquido em ratos acordados, Ãs 6, 12 e 24 horas apÃs a remoÃÃo cirÃrgica de um ou ambos os rins. Em todos os protocolos experimentais, o esvaziamento gÃstrico e o trÃnsito gastrintestinal foram determinados segundo a tÃcnica descrita por Reynell & Spray. O esvaziamento gÃstrico e o trÃnsito gastrintestinal foram significativamente reduzidos Ãs 6, 12 e 24 horas apÃs ambos os rins terem sido removidos. A remoÃÃo de um Ãnico rim nÃo teve efeito sobre o esvaziamento gÃstrico e o trÃnsito gastrintestinal. Houve um acentuado aumento no volume sangÃÃneo bem como nos nÃveis plasmÃticos de urÃia e creatinina apÃs a nefrectomia bilateral. Em seguida, avaliamos se este fenÃmeno foi causado pela azotemia. Num determinado grupo de animais observamos que a infusÃo de urÃia e creatinina nÃo teve efeito sobre o esvaziamento gÃstrico e o trÃnsito gastrintestinal nos animais intactos. AlÃm disso, a retraÃÃo de 30% do volume sangÃÃneo efetivo reverteu o retarde no esvaziamento gÃstrico e no trÃnsito gastrintestinal nos animais submetidos a nefrectomia bilateral. Em sÃntese, a nefrectomia bilateral induz a inibiÃÃo da motilidade gastrintestinal que parece ser ocasionada pela hipervolemia e nÃo pela azotemia induzida pela nefrectomia bilateral.
Renal failure leads to important gastrointestinal functional changes. However, there are only few studies focused on the relationship between renal failure and gastrointestinal tract physiology. In this work we studied the gastric emptying (GE) and gastrointestinal (GI) transit of liquid 6, 12 and 24hr after awake rats had one or both kidneys surgically removed. In both experimental protocols, GE and GI transit were measured according to Reynell & Spray procedures. GE and GI transit were significantly reduced 6, 12 and 24hr after both kidney removal. Removal of only one kidney had no effect on GE and GI transit. Blood volume was greatly increased after bilateral kidney removal as well as plasmatic urea and creatinine levels. We also evaluated whether this phenomenon was caused by azotemia. In a separate group of animals, we observed that urea and creatinine infusions had no effect on GE and GI transit in intact animals. In addition, bleeding up to 30% of blood volume reversed GE and GI transit inhibitions in animals submitted to bilateral kidney removal. In summary, bilateral nephrectomy leads to GI motility inhibition, which seems to be due to hypervolemia and not to post nephrectomy azotemia.

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Acute Renal Failure can be defined as an abrupt and sustained reduction in the glomerular filtration rate with a consequent retention of nitrogenous waste products. Despite the development in treatment, mortality remains high, varying beetween 50 and 70%. In hospitalised patients the incidence is about 5% but in respect to intensive care units it varies from 10 to 30%. In the last three decades, the characteristics of patients who suffer from acute renal failure changed dramatically. Before the advent of dialytic treatment, the main causes of mortality were uraemia, hyperkalaemia and the cardiac complications arising from volume overload. Nowadays, the causes are sepsis, cardiopulmonary failure, nephrotoxic drugs, and post renal transplantation complications. Multiple organ dysfunction, disseminated intravascular coagulation and diabetes mellitus are morbid conditions that can aggravate the prognosis of acute renal failure in intensive care units. Due to the high prevalence of diabetes mellitus in the population, this study intends to evaluate its influence in the morbidity and mortality of patients suffering from acute renal failure in the intensive care unit of Hospital de Base of São José do Rio Preto, Brazil was made in the period from January 1997 to December 2000. A total of 255 (25%) of the patients were diabetic and 765 (75%) were not. Demographic data, the presence of underlying diseases, aetiology, types, the clinical features and complications of acute renal failure were evaluated. Besides these, the presence of multiple organ failure syndrome was observed. In the study population 64% were male, 46% were more than 60 years old and 85% had one or more concomitant diseases. The ischaemic aetiology predominated in 53% of cases and a clinical cause was the most common type seen at 57%. The means and standard deviations of the Apache II score and creatinine levels (mg/dL) were 20.5 + 6.7 and 3.7 + 2.0 respectively. The prevalence of disseminated intravascular coagulation, shock, liver failure and respiratory failure were 32%, 69%, 15% and 79% respectively. Among the observed complications hyperkalaemia was seen in 35%, acidosis in 70%, sepsis in 61%, systemic arterial hypertension in 14%, bleeding in 22%, central nervous system disfunction in 44% and mortality in 71% of the cases. The demographic data, clinical features, morbidity and mortality due to acute renal failure of diabetic and non-diabetic individuals were compared. The hyperkalaemia, acidosis, respiratory failure, shock, central nervous system dysfunction, hypervolaemia and the bleeding were similar in both groups. A logistic regression analysis did not demonstrate a significant association between diabetes mellitus and mortality. An ischaemic aetiology, the failure of three or more organs, hyponatraemia and acidosis exhibited significant association between mortality and acute renal failure. In conclusion, the diabetic patients were older involving fewer men, with less oliguria, disseminated intravascular coagulation, hyponatraemia and liver failure than the non-diabetic individuals. Diabetes mellitus had no influence on the mortality due to acute renal failure in the intensive care unit.
A insuficiência renal aguda pode ser definida como uma redução abrupta e sustentada da taxa de filtração glomerular com conseqüente retenção de produtos nitrogenados. Apesar da evolução terapêutica, a sua mortalidade ainda continua elevada, variando entre 50 e 70%. Em pacientes hospitalizados, a sua incidência está próxima de 5% e, especificamente, em unidades de terapia intensiva, varia entre 10 e 30%. Nas últimas três décadas, as características dos pacientes acometidos de insuficiência renal aguda alteraram-se profundamente. Antes do advento do tratamento dialítico, as principais causas de mortalidade eram a uremia, a hipercalemia e as complicações cardiológicas decorrentes da sobrecarga de volume. Atualmente, são a sepse, a insuficiência cardiopulmonar, drogas nefrotóxicas e complicações pós-transplante renal. Quanto ao prognóstico de insuficiência renal aguda em unidades de terapia intensiva, a disfunção de múltiplos órgãos, a coagulação intravascular disseminada e o diabete melito são condições mórbidas que podem piorar a sua evolução. Devido à alta prevalência de diabete melito na população, o presente trabalho propôs-se avaliar a sua influência na morbidade e mortalidade da insuficiência renal aguda em unidade de terapia intensiva. Para tal, foram estudados, retrospectivamente, 1020 pacientes com insuficiência renal aguda internados na unidade de terapia intensiva do Hospital de Base de São José do Rio Preto, Brasil, no período de janeiro de 1997 a dezembro de 2000, dos quais, 255 (25%) eram diabéticos e 765 (75%) não diabéticos. Foram avaliados dados demográficos, presença de doenças de base, etiologia, tipos, quadro clínico e complicações de insuficiência renal aguda e ainda a presença de síndrome de disfunção de múltiplos órgãos. Entre a população estudada, 64% eram do sexo masculino, 46% tinham mais de 60 anos de idade, e 85% tinham uma ou mais doenças concomitantes. Nota de Resumo A etiologia isquêmica predominou com 53%, e a causa clínica foi o tipo mais freqüente com 57%. As médias e os desvios padrão de apache II e creatinina (mg/dL) foram 20,56,7 e 3,7+2 O respectivamente. A prevalência de coagulação intravascular disseminada, de choque, de insuficiência hepática e respiratória foi 32%, 69%, 15% e 79%, respectivamente. Entre as complicações, observamos a hiperpotassemia em 35%, a acidose em 70%, a sepse em 61%, a hipertensão arterial sistêmica em 14%, os sangramentos em 22%, a disfunção do sistema nervoso central em 44% e a mortalidade em 71%. Foram comparados, entre os diabéticos e os não diabéticos, os dados demográficos, quadro clínico, morbidade e mortalidade de insuficiência renal aguda. A hipercalemia, a acidose, a insuficiência respiratória, a sepse, o choque, a disfunção do sistema nervoso central, a hipervolemia e os sangramentos foram similares em ambos os grupos. A análise de regressão logística não mostrou associação significante entre diabete melito e a mortalidade. A etiologia isquêmica, a presença de três ou mais insuficiências de órgãos, a hiponatremia e a acidose foram de forma significante associadas com a mortalidade de insuficiência renal aguda. Em conclusão, os diabéticos foram mais idosos, menor prevalência de masculinos, menos oligúria, coagulação intravascular disseminada, hiponatremia e falência hepática do que os não diabéticos. O diabete melito não teve influência na mortalidade da insuficiência renal aguda em unidade de terapia intensiva.

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Nephrotoxicity is the main adverse effect of aminoglycoside use. There are few information about its prevalence and risk factor in intensive care unit patients. Objectives: To assess the prevalence, mortality and risk factors for aminoglycoside nephrotoxicity in ICU patients. Casuistic and Method: In order to assess the prevalence of, and risk factors for aminoglycoside nephrotoxicity in the ICU, 360 consecutive patients starting aminoglycoside therapy in the ICU with a baseline calculated GFR (cGFR) ≥30 ml/min/1.73 m2 were evaluated. Results: Of them, 209 (58%) developed aminoglycoside-induced nephrotoxicity (AKI, decrease in cGFR >20% from baseline), while 151 did not (non-AKI). Both groups had similar baseline cGFR. The AKI group developed a lower cGFR nadir (45 ± 27 vs. 79 ± 39 ml/min/1.73 m2, p<0.001), was older (56 ± 18 y vs. 52 ± 19 y, p=0.033), had a higher prevalence of diabetes (19.6% vs. 9.3%, p=0.007), used other nephrotoxic drugs (51% vs. 38%, p=0.024) and iodinated contrast more frequently (18% vs. 8%, p=0.0054), showed higher prevalence of hypotension (63% vs. 44%, p=0.0003), shock (56% vs. 31%, p<0.0001), and jaundice (19% vs. 8%, p=0.0036). Mortality was 44.5% in the AKI and 29.1% in the non-AKI groups (p=0.0031). A logistic regression model identified as significant (p<0.05) independent factors affecting aminoglycoside-induced nephrotoxicity baseline cGFR<60 ml/min/1.73 m2 (OR 0.42), diabetes (OR 2.13), simultaneous use of other nephrotoxins (OR 1.61) or iodinated contrast (OR 2.13), and hypotension (OR 1.83). Conclusion: The AKI was frequent among ICU patients using aminoglycoside, and it was associated with high mortality. The presence of diabetes, hypotension, simultaneous use of other nephrotoxic drugs, and iodinated contrast were independent risk factors for the development of aminoglycoside-induced nephrotoxicity.
Nefrotoxicidade é a principal complicação do uso de aminoglicosídeos. Existem poucas informações sobre a prevalência e os fatores de risco para nefrotoxicidade por aminoglicosídeos em paciente internados em unidades de terapia intensiva. Objetivos: Avaliar a prevalência, a mortalidade e os fatores de risco para nefrotoxicidade por aminoglicosídeos em pacientes internados em Unidade de Terapia Intensiva geral. Casuística e Métodos: Foram avaliados a prevalência, os fatores de risco e a mortalidade da nefrotoxicidade por aminoglicosídeo de 360 pacientes internados em terapia intensiva com filtração glomerular calculada por fórmula (MDRD, RFG) basal ≥30ml/min/ 1,73m2, que iniciaram o uso do antibiótico na terapia intensiva; nefrotoxicidade foi definida como queda >20% na RFG em relação ao RFG basal. Resultados: Entre os pacientes estudados 209 (58%) desenvolveram nefrotoxicidade (IRA) e 151 não alteraram a função renal (não IRA). Ambos os grupos (média±desvio padrão) tinham RFG basal similar (8942 ml/min/ 1,73m2 no grupo IRA versus 84±42 ml/min/ 1,73m2 no grupo não IRA). O grupo IRA teve menor nadir de RFG (45±27 ml/min/ 1,73m2 versus 79±39 ml/min/ 1,73m2, p<0,001), idade maior (5618 anos versus 5219 anos, p=0,033), maior prevalência de diabetes (19,6% versus 9,3%, p=0,007), uso simultâneo mais freqüente de outras drogas nefrotóxicas (51% versus 38%, p=0,024) e contraste (18% versus 8%, p=0,0054), maior prevalência de hipovolemia (44% versus 27%, p=0,001), hipotensão (63% versus 44%, p=0,0003), choque (56% versus 31%, p<0,0001) e icterícia (19% versus 8%, p=0,0036). A mortalidade foi 44,5% no grupo IRA e 29,1% no grupo não IRA (p=0,0031). A análise por regressão logística identificou como fatores de risco independente para a nefrotoxicidade por aminoglicosídeo, RFG basal <60ml/min/1,73m2 [OR 0,42 (IC 95% 0,24-0,72, p=0,02)], diabetes [OR 2,13 (IC 95% 1,01-4,49, p=0,046)], uso simultâneo de outras drogas nefrotóxicas [OR 1,61 (IC 95% 1,00-2,59, p=0,048)], uso de contraste iodado [OR 2,13 (IC 95% 1,02-4,43, p=0,043)] e hipotensão [OR 1,83 (IC 95% 1,14-2,94, p=0,012)]. Conclusões: Nefrotoxicidade por aminoglicosídeo foi freqüente e associada a alta mortalidade em pacientes de UTI. A presença de diabetes, hipotensão, uso simultâneo de outras drogas nefrotóxicas e contraste iodado foram fatores de risco independentes para o desenvolvimento de nefrotoxicidade.

Antimicrobial dosage adjustment for patients with acute or chronic kidney disease undergoing extracorporeal renal replacement therapy is a complex problem frequently under investigated for several drugs. In this setting, the rational approach for appropriate dosage regimen is fundamental, not only to achieve efficacy of pharmacological treatment, but also to avoid toxicity risks. In addition, when an antimicrobial agent is administrated, it has to be taken into account the emergence of resistant pathogen microorganisms. The purpose of this research project was to set up an in vitro models of hemoperfusion (HP) and hemofiltration (HF) techniques in order to investigate antimicrobial removal during extracorporeal circulation. In particular, it focuses on drug adsorption by sorbent or membrane polymers, which is almost unexplored phenomenon reported in literature. The first in vitro model was set up in a direct HP (DHP) mode using a prototype dialysis machine (Bellco, R&D Electronic Division, Mirandola, Italy) with Lixelle S-35 cartridge (Kaneka Corporation, Osaka, Japan). This medical device is a sorbent developed for a selective removal of β2-microglobulin (β2-MG) in dialysis-related amyloidosis (DRA) of chronic kidney disease patients. The aim of the study was to investigate the vancomycin (VAN) and teicoplanin (TEC) adsorption removal by DHP with Lixelle S-35 cartridge. VAN and TEC experiments showed that the cartridge has a high adsorption capacity for both glicopeptides. In the case of TEC, the total mass introduced into the system was adsorbed by Lixelle polymer bed. Considering the high TEC adsorption rate, it was developed and performed an in vitro tool with Lixelle polymer in order to evaluate the possible competitive binding between TEC and β2-MG during adsorption process. Based on these results, TEC and β2-MG did not compete for binding sites of Lixelle polymer. On the contrary, β2-MG seems to enhance the adsorption of TEC. These data suggest that a supplemental dose should be administered in DRA patients when Lixelle S-35 is used for both VAN and TEC. The second in vitro model was configured in DHP as previous system, but it was optimized as close as possible to in vivo conditions. The mock DHP treatments were performed to evaluate gentamicin (GEN) and tobramycin (TOB) adsorption removal by using Bellco prototype dialysis machine with Lixelle S-35 cartridge. XIV GEN was rapidly adsorbed onto polymer bed during experiments without antimicrobial release by the sorbent cartridge. GEN results indicated that a supplemental dose should be taken into account in DRA patients receiving DHP with Lixelle S-35. Conversely, TOB, after its rapid adsorption, was released into the extracorporeal circulation: the redistribution phenomenon occurred. Therapeutic drug monitoring (TDM) should be performed to measure TOB plasma levels before considering an supplemental dose when Lixelle S-35 is used. The antimicrobial adsorption phenomenon could also affect HF treatments and therefore hemofilter membranes. In this direction, it was set up an miniaturized in vitro system with CARPEDIEM dialysis machine (Cardio-Renal Pediatric Dialysis Emergency Machine; Bellco, Mirandola, Italy) using a polysulfone membrane (Medisulfone; Medica, Medolla, Italy). The HF in vitro model was used to study the antimicrobial drug removal of linezolid (LZD) and TOB. LZD HF treatments described a rebound phenomenon of its plasma levels. Indeed, the maximum LZD value adsorbed was observed at the beginning of the experiments, then it was partially released from polysulfone membrane. Although it is still unclear if LZD is completely released from the membrane, the redistribution phenomenon should be considered in patients with acute renal failure (ARF) undergoing continuous HF. The LZD dosage adjustment requires TDM as a tool for defining a potential supplemental dose. On the other side, the TOB adsorption phenomenon can be considered negligible related to the antimicrobial mass removed from the extracorporeal circulation. TOB was primarily cleared by convection during HF experiments. These findings indicate that TOB dose should be adjusted according to the ultrafiltration rate in ARF patients receiving continuous HF. The rationale approaches suggested for antimicrobial dosage the adjustment concern the intimate drug removal of specific extracorporeal techniques investigated by the present research project. In order to prescribe the optimal antimicrobial dosage regimen, clinicians must consider these experimental evidences in a relationship with patient’s pathophysiology which also impacts on pharmacokinetic of drugs.
L’adeguamento del dosaggio degli antimicrobici nei pazienti con insufficienza renale sottoposti a trattamento extracorporeo sostitutivo della funzionalità renale è un problema complesso e affrontato in maniera frammentaria in letteratura. Esso richiede delle basi solide e razionali su cui fondare il regime posologico del farmaco per ragioni di efficacia terapeutica, ma anche, più raramente, per evitare fenomeni di tossicità. Inoltre, quando ad essere sotto dosato è un antimicrobico, lo sviluppo di ceppi batterici resistenti rappresenta un ulteriore problema. Su queste premesse si è fondato il progetto di ricerca. L’obiettivo è stato quello di sviluppare dei modelli in vitro di emoperfusione (HP) ed emofiltrazione (HF) al fine di studiare la farmacocinetica extracorporea di antimicrobici, per i quali non esiste letteratura scientifica sufficiente in queste tipologie di trattamento dialitico. In particolare, il progetto è stato focalizzato sul fenomeno dell’adsorbimento degli antimicrobici su sorbenti e membrane durante la circolazione extracorporea, fenomeno scarsamente investigato in letteratura. Un primo modello in vitro di HP diretta (DHP) è stato messo a punto su un monitor prototipo (Bellco, R&D Electronic Division, Mirandola, Italia), per investigare sulla rimozione extracorporea dei glicopeptidi vancomicina (VAN) e teicoplanina (TEC), con la cartuccia adsorbente Lixelle S-35 (Kaneka Corporation, Osaka, Giappone). Quest’ultima è un dispositivo medico impiegato per la rimozione della β2-microglobulina (β2-MG), nei pazienti con insufficienza renale cronica (IRC) affetti da amiloidosi dialisi correlata (DRA). Gli esperimenti effettuati con la VAN e la TEC hanno evidenziato un elevato adsorbimento irreversibile dei glicopeptidi da parte della cartuccia Lixelle S-35. Durante i trattamenti di DHP con TEC, tutto l’antimicrobico introdotto nel sistema è stato rimosso dal circolo extracorporeo. Per tale ragione, in una fase successiva di studio, è stato sviluppato un tool in vitro, impiegando il polimero contenuto in Lixelle, per valutare il possibile fenomeno competitivo tra TEC e β2-MG durante il processo di adsorbimento. Tale sperimentazione, non solo ha escluso il fenomeno competitivo tra i due composti, ma ha messo in luce che la β2-MG favorisce l’adsorbimento della TEC sul polimero. Queste evidenze sperimentali indicano la necessità d’impiegare una dose supplementare per entrambi i glicopeptidi, quando la XII cartuccia Lixelle S-35 viene utilizzata per il trattamento della DRA nei pazienti con IRC. Su questo filone di ricerca, un secondo modello in vitro di DHP, ottimizzato rispetto al precedente, è stato sviluppato per investigare sulla rimozione extracorporea degli aminoglicosidi gentamicina (GEN) e tobramicina (TOB), sempre con la cartuccia adsorbente Lixelle S-35 sul prototipo Bellco. Dalla sperimentazione condotta sulla GEN è emerso che una dose supplementare deve essere utilizzata anche per questo antimicrobico, dato l’adsorbimento irreversibile sul letto polimerico. Diversamente, la TOB dopo un rapido adsorbimento, è stata ridistribuita al circolo extracorporeo. Il fenomeno di adsorbimento reversibile, osservato per la TOB, suggerisce di monitorare le concentrazioni plasmatiche del farmaco quando viene impiegata la cartuccia Lixelle S-35, prima di considerare una dose supplementare di TOB. Per quanto riguarda il fenomeno dell’adsorbimento durante l’HF, è stato costruito un sistema in vitro miniaturizzato sul monitor CARPEDIEM (Cardio-Renal Pediatric Dialysis Emergency Machine; Bellco, Mirandola, Italia), con una membrana in polisulfone (Medisulfone; Medica, Medolla, Italia), per studiare la rimozione extracorporea del Linezolid (LZD) e della TOB. Nella sperimentazione con il LZD, il farmaco dopo un rapido adsorbimento sulla membrana, si è ridistribuito alla circolazione extracorporea con rebound delle concertazioni plasmatiche. Il fenomeno osservato, peraltro non concluso, indica che per il LZD è necessario monitorare le concentrazioni plasmatiche prima di adeguare il dosaggio dell’antimicrobico nei pazienti con insufficienza renale acuta, sottoposti a trattamento di HF continua. Viceversa, lo schema posologico della TOB deve considerare la prescrizione dialitica, in termini di flusso di ultrafiltrazione impostato. Ciò è suggerito dal fatto che non è stato osservato un adsorbimento, sulla membrana, significativo ai fini clinici. Queste evidenze, riguardanti l’intimo meccanismo di rimozione extracorporea, dovrebbero essere prese in considerazione dal clinico unitamente alla fisiopatologia del paziente, in quanto la stessa può influenzare la farmacocinetica degli antimicrobici oggetto di questo progetto di ricerca.

The critical function of the kidney is to regulate the body’s extracellular fluid volume to maintain homeostasis. When insults to the kidney occur, as in the case of kidney ischemia, the function of the kidney to filter metabolic wastes and reabsorb essential solutes is compromised, leading to a variety of clinical manifestations. Current metrics of kidney function are measured by the rise of a single analyte, the serum creatinine, which implies injury of the kidney tubule and its epithelial cells and is encapsulated by the term Acute Kidney Injury (AKI). Yet, creatinine does not specify the etiology, the cell type, or the molecular pathways that are affected by the acute decreases in kidney excretory function. During my thesis work, I hypothesized that there is a pathogenetic heterogeneity of kidney injury and a specificity of location, timing, and molecular mechanisms, unique to each of these three injury models: kidney ischemia, volume depletion, and urinary tract infection. Using genetic mouse models, RNA-sequencing, and a range of molecular biology techniques, I have found (1) kidney ischemia activates inflammatory responses, signal transduction pathways, and epithelial repair and reprogramming, that are not activated in volume depletion, (2) which in contrast, is a transient metabolic condition, inducing genes regulating energy metabolism that were reversible upon rehydration. Lastly, (3) I have found that urinary tract infection, particularly one that invades the kidney, involves a novel heme transport system in the collecting duct of the kidney, that may contribute to nutritional defenses against bacterial pathogens. Each of these findings is explored in specific aims and experiments, which I detail here in my thesis.

BACKGROUND: Acute renal failure (ARF) is a clinical syndrome characterised by a rapid deterioration of kidney function over hours to days which may recover/return to normal values following appropriate therapy. Various scoring systems currently exist to predict the severity and outcome in patients with ARF. Recently the Acute Dialysis Quality Initiative (ADQI) Group has established the RIFLE (Risk of injury, Injury to the kidney, Failure of kidney function, Loss of kidney function, and End-stage kidney disease) classification which has become widely used globally. There is however, limited data on its use in Africa. In order to provide data on the use of RIFLE criteria from an African facility, we conducted a retrospective chart review to assess the outcome of ARF in patients admitted in the Intensive Care Unit (ICU) at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH). The data reviewed covered the period between January 1st to December 31st 2008. METHODS: This was a retrospective chart review conducted in the adult multi-disciplinary intensive care unit at CMJAH between January 1st to December 31st 2008. Medical records of patients admitted during this period were reviewed and patients with acute renal failure were identified. Demographic data, relevant clinical information such as reason for ICU admission, number of organ(s) involved, presence of co-morbidity, RIFLE criteria on admission and on discharge, modality and duration of treatment of ARF, need for mechanical ventilation and or inotropic support were recorded. For the purpose of this study, serum creatinine based on RIFLE classification was used to define ARF. Statistical analysis was performed using the data collected and STATA version 11. The Primary outcome, which was survival or death, was correlated with the maximum RIFLE classification during patients’ ICU stay. The study was approved by the Human Research Ethics Committee medical (HRECM) of the University of Witwatersrand with Clearance certificate number M090906 RESULTS: One hundred and ninety three (193) patients with acute renal failure were included in the study. The mean APACHE II score was 19 ± 6.4 SD, with the maximum score documented being 38. Patient ages ranged from 21 – 92 years with a mean of 50.5 years ± 18.3SD. Fifty two percent of the patients were male and 48% were female. Majority of patients were black (63%) with 36.8% being other race groups. According to RIFLE criteria on admission, 40.9% had normal renal function, 23.3%, 14.0% and 21.8% were in RIFLE R, I and F classes respectively. The overall mortality in ICU was 59.9%. Of those patients discharged to the ward from ICU, 14.1% subsequently demised. Factors associated with mortality in ICU included race, chronic pulmonary disease, mechanical ventilation, inotropic support, need for ventilation and inotropic support, dialysis and maximum RIFLE criteria reached in ICU. After multivariate analysis using Cox proportion regression model, factors such as race, inotropic support, need for both ventilation and inotropic support and maximum RIFLE criteria were independently associated with mortality in ICU, whereas for patients discharged from ICU to the ward, only cancer was found to be independently associated with mortality. Based on RIFLE criteria, patients in R, I, and F class had 5.41, 3.17 and 5.69 greater risk of dying respectively as compared to patients with normal renal function (Adjusted HR 5.41 95%CI 2.66 - 11.0, p-Value 0.000 for R class, HR 3.17 95%CI 1.65 - 6.07, p-value 0.001for I class, and HR 5.69 95%CI 2.93 - 11.06, p-value 0.001 for F class) CONCLUSION: RIFLE criteria is a useful tool for predicting the outcome of acute renal failure in the intensive care unit.

Indiana University-Purdue University Indianapolis (IUPUI)
The young field of gene therapy offers the promises of significant progress towards the treatment of many different types of human diseases. Gene therapy has been proposed as an innovative way to treat Acute Kidney Injury (AKI). Through proteomic analysis, the upregulation of two enzymes, IDH2 and SULT1C2, within the mitochondrial fraction has been identified following ischemic preconditioning, a treatment by which rat kidneys are protected from ischemia. Using the hydrodynamic fluid gene delivery technique, we were able to upregulate the expression of IDH2 and SULT1C2 in the kidney. We found that the delivery of IDH2 plasmid through hydrodynamic fluid delivery to the kidney resulted in increased mitochondrial oxygen respiration compared with injured kidneys without gene delivery. We also found that renal ischemic preconditioning altered the membrane fluidity of mitochondria. In conclusion, our study supports the idea that upregulated expression of IDH2 in mitochondria can protect the kidney against AKI, while the protective function of upregulated SULT1C2 needs to be further studied.

Indiana University-Purdue University Indianapolis (IUPUI)
Acute Kidney Injury (AKI) is a prevalent and significant problem whose primary treatment is supportive care. Ischemic preconditioning is a strategy used to protect organs from ischemic injury via a prior injury. Ischemic preconditioning in the kidneys has been shown to confer protection onto kidneys from subsequent ischemic insults with attenuated serum creatinine values in treated rats. In the preconditioned kidneys, the enzyme IDH2 was discovered to be upregulated in the mitochondria. Hydrodynamic fluid delivery to the kidney was found to be a viable technique for delivering this gene to the kidney, resulting in artificially upregulated expression of IDH2. Via a two-pronged effort to discern the functional significance of ischemic preconditioning and hydrodynamic IDH2 fluid injections, we performed mitochondrial oxygen respiration assays on both preconditioned and injected kidneys. We found that renal ischemic preconditioning resulted in no significant difference between sham and preconditioned, subsequently injured kidneys, which is similar to the results from the serum creatinine studies. Hydrodynamically IDH2-injected, and subsequently injured kidneys respire significantly better than vehicle injected, and subsequently injured kidneys, which shows that hydrodynamic injections of IDH2 protects kidneys against injury, and partially mimics the effects of preconditioning.

Indiana University-Purdue University Indianapolis (IUPUI)
Advancements in human genomics have simultaneously enhanced our basic understanding of the human body and ability to combat debilitating diseases. Historically, research has shown that there have been many hindrances to realizing this medicinal revolution. One hindrance, with particular regard to the kidney, has been our inability to effectively and routinely delivery genes to various loci, without inducing significant injury. However, we have recently developed a method using hydrodynamic fluid delivery that has shown substantial promise in addressing aforesaid issues. We optimized our approach and designed a method that utilizes retrograde renal vein injections to facilitate widespread and persistent plasmid and adenoviral based transgene expression in rat kidneys. Exogenous gene expression extended throughout the cortex and medulla, lasting over 1 month within comparable expression profiles, in various renal cell types without considerably impacting normal organ function. As a proof of its utility we by attempted to prevent ischemic acute kidney injury (AKI), which is a leading cause of morbidity and mortality across among global populations, by altering the mitochondrial proteome. Specifically, our hydrodynamic delivery process facilitated an upregulated expression of mitochondrial enzymes that have been suggested to provide mediation from renal ischemic injury. Remarkably, this protein upregulation significantly enhanced mitochondrial membrane potential activity, comparable to that observed from ischemic preconditioning, and provided protection against moderate ischemia-reperfusion injury, based on serum creatinine and histology analyses. Strikingly, we also determined that hydrodynamic delivery of isotonic fluid alone, given as long as 24 hours after AKI is induced, is similarly capable of blunting the extent of injury. Altogether, these results indicate the development of novel and exciting platform for the future study and management of renal injury.

The thesis principles of nursing care for a child with renal failure is engaged in nursing activities in nephrology and cardiology intensive care unit of a hospital in Prague - Motol. Acute renal failure is defined as a condition where there is a sudden , usually reversible renal impairment, which were totally wrong , or very little damage. Besides the medical approach to this disease in acute renal failure urgently needed highly skilled nursing care. When nursing care for sick children teamwork is essential . A child with acute renal failure , always requires hospitalization in intensive care.The thesis is divided into a theoretical and an empirical part . In the theoretical part , attention is paid to the current issue of treating a child with acute renal failure. The work also includes anatomy and physiology of the kidney , and nephrologic basic concepts. Attention is also pays attention to the methods of investigation , communication with patients and nursing diagnoses . There acquaintance with elimination methods and nursing care for the child , unless they use the elimination method .

A high-performance liquid chromatography was developed to assay levofloxacin and vancomycin. Fluorescence polarization immunoassay was to assay amikacin. The oseltamivir carboxylate and telavancin concentrations were assayed by high-performance liquid chromatography coupled with tandem mass spectrometry.
An in vitro model was utilized to examine adsorption of antibiotics onto haemofilters. In order to test antibiotics from a range of classes, levofloxacin, amikacin, vancomycin, telavancin, and oseltamivir carboxylate were studied.
In summary, the antibiotic adsorption by haemofilters is a complex process. Both characteristics of antibiotics and haemofilters may determine adsorption. Among the studied antibiotics, in vitro adsorption of amikacin by PAN filters may have clinical significance, thus the routine monitoring of amikacin peak concentration in vivo during CRRT is recommended.
In the in vitro model, blood was pumped from an agitated, glass mixing chamber (heated using an automatic water bath), around a circuit and returned to the mixing chamber using a haemofiltration machine. Ultrafiltrate was also returned to the mixing chamber to constitute a closed circuit. As a result any decrease in drug concentration could only be due to adsorption to the filter and extracorporeal circuit, spontaneous degradation or metabolism by red cells.
The main findings were: (1) low adsorption of levofloxacin and vancomycin by haemofilters at clinically relevant concentrations; (2) significant absolute adsorption of amikacin by polyacrylonitrile haemofilters; (3) the adsorption of antibiotics was membrane-material dependent with greater adsorption by polyacrylonitrile filters; (4) lack of relationship between membrane surface area and amikacin adsorption; (5) the adsorption of levofloxacin is reversible, contrary to irreversibility of vancomycin and amikacin; (6) sieving coefficient of oseltamivir is very near to 1.0.
This thesis investigated: (1) the extent of antibiotic adsorption (levofloxacin, vancomycin, amikacin, telavancin and oseltamivir carboxylate) by haemofilters; (2) the time course of antibiotic adsorption by haemofilters; (3) the effects of plasma albumin concentration, initial dosage, pH, filter membrane material, filter membrane surface area and repeated dosing on adsorption; (4) the reversibility or irreversibility of adsorption; (5) clearance of oseltamivir carboxylate and telavancin by ultrafiltration.
Up to 25% of critically ill patients develop acute renal failure with sepsis being the most common cause. Outside of North and South America, these patients usually receive continuous renal replacement therapy (CRRT) which utilizes high flux haemofilter membranes. Thus it is common for these patients to be concurrently receiving antibiotics and CRRT. However, information about the adsorptive capacity of various haemofilters for most drugs is lacking.
"September 2007."
Advisers: Charles Gomersall; Tony Gin.
Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4659.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2007.
Includes bibliographical references (p. 147-164).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract in English and Chinese.
School code: 1307.

This dissertation deals with the issue of continuous elimination methods in intensive care, and of subsequently creating teaching materials for incoming nurses. The goal was to create teaching materials for incoming nurses. These teaching materials should help incoming nurses work with a device intended for continuous elimination methods. The dissertation is divided into a theoretical and practical part. The empirical part was implemented in the form of a qualitative research, using semi-structured interviews with respondents at the Accident and Emergency Ward of Nemocnice České Budějovice a.s. at the RES 2 station. The first stage of research was implemented by conducting interviews with the respondents. These interviews were recorded in the form of detailed notes which were later transcribed in order to prevent losses of data and inaccuracies. Subsequently, categories were established and, proceeding from these categories, schemes created using the ATLAS programme. The second stage consisted of creating an instruction video and teaching materials for incoming nurses. As a part of the third stage of research, the created video and teaching materials were presented at the Accident and Emergency Ward for evaluation. Then, interviews with the original respondents were re-conducted. During these interviews, the respondents were tasked with evaluating whether the teaching materials fulfil their needs and whether they will be usable in practice. The learned information was then arranged in corresponding schemes. Two goals were set with regards to the practical part. The first goal was to determine which form of teaching materials is suitable for incoming nurses. The second goal was to establish the benefits and usability of the created materials in practice. Based on the goals, two research questions were formulated. The first research question was: Is the form of the teaching materials suitable for incoming nurses? The second research question was: What is the benefit of the created materials in practice? Based on the research, it was discovered that most of the respondents would welcome teaching materials in the form of printed leaflets; however, opinions on the option of creating a video were also heard. Therefore, an instruction video, suitably complementing the printed leaflet, was created. The third part of research implied that most of the eight interviewed respondents were satisfied with the teaching materials. Three respondents suggested supplementing the printed leaflet with additional images. All eight respondents agreed that in their opinion, the provided teaching materials would make it easier for incoming nurses to familiarize themselves with the issues discussed. The head nurse at the Accident and Emergency Ward views the created teaching materials as beneficial. She intends to continue using these materials at her ward.

碩士
慈濟大學
生理暨解剖醫學碩士班
99
The mammalian circadian timing system is a hierarchically organized network of molecular oscillators driven by the suprachiasmatic nucleus (SCN) of hypothalamus. The molecular basis of circadian timing involves interlocking positive and negative feedback loops which culminate in the rhythmic expression and activity of a set of circadian-clock genes. These genes include the Period (Per1, Per2 and Per3), Cryptochrome (Cry1 and Cry2), brain and muscle Arnt like protein-1 (Bmal1) and circadian locomotor output cycles kaput (Clock). Past studies have shown that the circadian-clock genes present not only in the central nervous system but also in numerous peripheral organs, such as the kidney. Renal excretion of water and major electrolytes exhibits a significant circadian rhythm. Various reports emphasize the importance of circadian-clock genes in the regulation of fluid and electrolyte balance. Recent studies demonstrate that loss of circadian-clock genes result in alteration of renal function. The major focus in this study is to determine the expression of circadian-clock genes in the acute renal failure (ARF). Adult male C57BL/6 mice were intraperitoneally administered folic acid (FA) to induce ARF. The levels of 24-h urinary volume and water intake were measured in individual metabolic cages. The mice were sacrificed at 4-h intervals of the daily cycle, starting at Zeitgeber time 2 (ZT2; time of light-on as ZT0 and light-off as ZT12) on day 3, 10 and 22 after FA injection. We found that the urinary volume and water intake volume began increased, and the body weight was decreased 1 day after FA injection, but the urinary volume and body weight were restored as the control at day 15 and 8, respectively. Histological examination showed disrupted brush borders and flattening of epithelia in the kidneys of FA-treated mice, indicating the occurrence of acute tubular necrosis. In this study, the levels of alpha subunit of epithelial sodium channel, sodium/hydrogen exchanger 3, serum/glucocorticoid regulated kinase 1, vasopressin V2 receptor, aquaporin-4 and rennin expression were decrease in FA-treated mice. The expression of Per1, Per2, Per3, Cry1, Cry2, Bmal1 and Clock were significantly altered not only in mRNA levels but also in circadian patterns in kidney of FA-treated mice. The levels of most gene expression after FA treatment did not restore as the control during the progression of ARF. Impairment in renal function may not only influence the several key regulators of water and sodium but also change the expression of circadian-clock genes. In conclusion, these data suggested that the expressions of circadian-clock genes and renal function-related genes were changed in folic acid nephrotoxicity.

Background: Every year, more than 2 million people undergo cardiac surgery including 15 000 Canadians (1). Acute kidney injury remain a frequent complication in this setting which can affect up to 39% of patients (2). This complication is associated with a significant increase in the risk of short-term and long-term mortality after cardiac surgery (1). Multiple mechanisms can lead to acute kidney injury in the peri-operative period which complexify prevention and treatment. Among them, multiple clinical factors can result in an increase in venous pressure leading to a state of systemic congestion deleterious to kidney function in addition to other organs. The detection of congestion at the bedside of patients after cardiac surgery could be used to identify patients at risk of developing congestive complications such as congestive acute kidney injury as well as opening possibilities for prevention and treatment. Doppler ultrasound is a non-invasive technology enabling the assessment of blood flow velocity within the venous system. A reduction of systemic venous compliance lead to the appearance of alterations in portal vein flow and intra-renal venous flow. The objectives of the work presented in this thesis were the following: To determine the prevalence and predictive factor associated with the appearance of venous flow alterations during the intra-operative and post-operative period, to determine if their detection is associated with acute kidney injury in the post-operative period and to determine the clinical significance of their detection in the immediate post-operative period. Main results: This thesis is comprised of 3 cohort studies including a total of 1497 ultrasound asessments in 362 patients. Alterations in venous Doppler signals were observed in a subtantial proportion of patients during the per-operative period, from 10.8% to 24.3% depending on the time of assessment and the site assessed. We observed significant correlations between venous Doppler alterations and other clinical markers of congestion including central venous pressure, NT-pro-BNP and fluid balance. Furthermore, we observed that portal flow pulsatility and abnormal patterns of intrarenal venous flow were correlated. Using repeated assessments in a cohort of 145 patients, we observed that portal flow pulsatility and severe alterations in intrarenal venous flow were associated with the subsequent development of acute kidney injury in the post-operative period. A re-analysis of this data suggested that a grading system combining mutliple Doppler assesments at intensive care admission after cardiac surgery including heaptic veins, the portal vein and intrarenal veins may be able to identify patients at risk of developping acute kidney injury with high specificity. Conclusions: In the context of cardiac surgery, Doppler ultrasound can be used to identify alterations in peripheral venous Doppler signals suggestive of a congestion phenomenon and may be able to anticipate complications related to venous congestion such as acute kidney injury.
Contexte : Chaque année, plus de 2 millions de personnes subissent une chirurgie cardiaque, dont 15 000 Canadiens (1). L’insuffisance rénale aiguë demeure une complication fréquente chez les patients subissant une chirurgie cardiaque atteignant une incidence jusqu’à 39 % dans la période postopératoire (2). Cette complication est associée à une augmentation du risque de mortalité à court et long termes. Plusieurs mécanismes peuvent engendrer l’insuffisance rénale aiguë dans la période peropératoire, ce qui complexifie la prévention et le traitement. Parmi ceux-ci, divers facteurs peuvent engendrer une augmentation des pressions veineuses menant à un état de congestion systémique qui affecte la fonction des reins ainsi que celle des autres organes vitaux. La détection de la congestion au chevet des patients durant la période intraopératoire et postopératoire pourrait permettre d’identifier les individus à risque de développer des complications de nature congestive telles que l’insuffisance rénale aiguë ainsi que de mettre en place des stratégies de prévention et de traitement. L’échographie Doppler est une technologie non invasive qui permet d’évaluer la vélocité du sang dans le réseau veineux. La diminution de la compliance veineuse entraine l’apparition d’altérations du flot veineux de la veine porte et des veines intrarénales. Les objectifs des travaux présentés dans cette thèse étaient les suivants : déterminer la prévalence ainsi que les facteurs prédicteurs de l’apparition de ces altérations durant la période peropératoire; déterminer si la détection de ces altérations est en mesure de prédire l’apparition d’insuffisance rénale aiguë dans la période postopératoire; et déterminer quelle est la signification clinique de l’apparition de ces signes dans la période postopératoire immédiate. Résultats principaux : Les travaux contenus dans cette thèse comportent trois études de cohorte comprenant 1497 examens échographiques chez 362 patients. La présence d’altération du flot veineux a été observée chez une proportion substantielle des patients durant la période post-opératoire, allant de 10.8% à 24.3% selon le site intérrogé et le moment où l’examen est effectué. Nous avons observé des associations entre les altérations du flot veineux et les autres marqueurs de congestion incluant la pression veineuse centrale, la mesure du NT-pro-BNP et la balance liquidienne. De plus, nous avons observé que la pulsatilité du flot portal est corrélée aux altérations du signal Doppler dans les veines intrarénales. Grâce à des examens répétées effectuées dans une cohorte de 145 patients, nous avons observé que la pulsatilité du flot portal et la présence d’un profil compatible avec une anomalie sévère du flot intrarénal veineux étaient associées indépendamment avec la survenue subséquente d’insuffisance rénale aiguë durant la période postopératoire. Une réanalyse de ces données nous a permis de constater qu’un système de gradation combinant la présence des altérations du flot veineux à plusieurs sites, incluant les veines hépatiques, la veine porte et les veines intrarénales, au moment de l’admission aux soins intensifs permet d’indentifier les patients qui développeront une insuffisance rénale aiguë avec une spécificité élevée. Conclusions : Dans le contexte de la chirurgie cardiaque, l’échographie Doppler peut être utilisée au chevet afin d’indentifier des altérations du flot veineux périphérique suggestives d’un phénomène de congestion et d’anticiper les complications de nature congestive tel que l’insuffisance rénale aiguë.