Dissertations / Theses on the topic 'Potassium Bromate'

Potassium bromate (KBrO3) is a drinking water disinfection by-product and may represent a health hazard if found to be carcinogenic for humans, as was determined in rats (DeAngelo et al., 1998; Hayashi et al., 1986; Kurokawa, 1985; Kurokawa et al., 1985; Kurokawa et al., 1986a; Kurokawa et al., 1982; Kurokawa et al., 1983a; Kurokawa et al., 1987a; Kurokawa et al., 1983b; Kurokawa et al., 1986b; Ohno et al., 1982; Onodera et al., 1985). The purpose of this research was to determine the mechanism of toxicity. The peritoneal mesothelium is a (rat) target organ of potassium bromate carcinogenicity, but has not been studied due to the inherent difficulties of working with this one cell layer-thick tissue. Data from a two-year bioassay were used to more precisely map the location of origin, revealing that these tumors in the male F344 rat originate on the mesorchium of the tunica vaginalis testis, the mesosplenium, or at a point in between. An in vitro cell culture system was developed to study the mechanism of toxicity. It was demonstrated that KBrO3 caused cell cycle arrest and markedly increased the number of apoptotic cells. KBrO3 is a powerful oxidant and glutathione (GSH) is the major cellular antioxidant. Therefore, GSH-related responses were studied revealing mesothelial cells contained substantially less GSH than a human hepatocellular carcinoma cell line (Hep-G2). Studies employing GSH ester or N-acetyl cysteine (a GSH precursor) pre-treatment demonstrated abatement of toxicity in mesothelial, but not Hep-G2, cells. Experiments carried out to determine the chemical or enzymatic nature of the reaction between GSH and KBrO3 revealed differences between the reaction kinetics of the unbuffered and buffered chemical and cell-free/cell lysate reactions, probably due to reaction pH. Both chemical and cellular reactions exhibited a similar first step reaction between GSH and KBrO3; thus, enzyme participation is probably not required. Experiments using diethylmaleate, which depletes GSH by a reaction involving KBrO3, showed that GSH depletion greatly enhanced KBrO3 toxicity, indicating GSH glutathione S-transferase, buthionine sulfoximine (which prevents synthesis of GSH) and was protective. This does not support the hypothesis that the reaction of KBrO3 and GSH itself produces a radical/reactive species that oxidatively damages lipids, proteins and DNA. Rather, depletion of GSH likely precedes oxidative damage. Gene expression studies demonstrated that peritoneal mesothelial cells displayed expression changes in a discrete set of genes, including oxidative stress-responsive genes, after treatment with KBrO3 for four or 12 hours. Mesothelial cells severely damaged by five days KBrO3 treatment recovered from complete cell cycle arrest after four weeks and exhibited explosive growth, focus formation and altered morphology. The redox imbalance created by GSH depletion appears to mediate increased expression of known oxidative stress responsive genes (e.g., HO-1,GADD45, GADD153, QR), activation of transcription factors (AP-1 and NFkB) and down-regulation of cell cycle initiating cyclins (and up-regulation of the CDK inhibitor p21waf1/cip1) in KBrO3-mediated toxicity. These alterations may permit cell survival, as observed after severe toxicity, and may be accompanied by transforming mutations or clastogenic changes. Taken together, these data suggest that mesothelial cells represent a population susceptible to KBrO3-mediated toxicity in vitro, and suggest that tissue susceptibility in vivo plays a role in the nascence of mesotheliomas in the male F344 rat.

Au cours du pétrissage, la consommation des thiols de bas poids moléculaire (BPM) affecte la structure du réseau de gluten, en raison de la participation de ces composés aux réactions d'échanges SH / SS avec les protéines. En panification, récemment, des enzymes fongiques ont été proposées comme alternative plus naturelle à l'emploi des améliorants chimiques (KBrO3, acide ascorbique) pour oxyder ces composés thiols BPM. Dans ce cadre, la sulfhydryle oxydase d'Aspergillus niger a été étudiée et son action a été comparée à celle du KBrO3 et de la glutathion (GSH) déshydrogénase de blé (GSH-DHase). Dans un 1er temps, le protocole de purification de la sax d'A. Niger mis au point a permis d'éliminer la catalase, contaminant majeur de l'échantillon. La caractérisation cinétique de la SOX a été menée. Une 2e partie a été consacrée à la mise au point de méthodes de dosage des formes réduite et oxydée (GSSG, CSSC et GSSC) du glutathion et de la cystéine. Ainsi, par CLHP couplée à un détecteur coulométrique ou UV, les GSH, CSH, GSSG, GSSC et CSSC ont pu être séparés et quantifiés. Les 3 disulfures ont été également analysés par gel filtration couplée à une détection UV. Une comparaison de la formation des disulfures par 3 différents systèmes oxydants, SOX, GSH-Dhase et KBrO3, a ensuite été réalisée à partir de mélanges de GSH et CSH. En dernier lieu, des associations enzymatiques en milieux modèles ont été examinées. Le mélange de SOX et de GSH-DHase conduit à une compétition pour la consommation du GSH. Parallèlement, l'association de SOX et de peroxydase de germe de blé (POD) a révélé que la SOX est capable d'activer la POD, en générant l'H2O2. Nous pouvons donc supposer que, dans la pâte, l'ajout de SOX peut influencer les réactions d'oxydoréduction, et par conséquent serait susceptible de modifier les propriétés de la pâte boulangère
During wheat flour dough mixing, low molecular weight (LMW) thiols consumption is known to influence the gluten network structure since these compounds can participate to exchange reactions SH / SS with proteins. In breadmaking, recently, fungal enzymes are proposed as "the natural alternative" to the use of chemical improving agents (KbrO3 ascorbic acid AA) to oxidise LMW thiols. In this respect, sulphydryl oxidase (SOX) from Aspergillus niger was studied and its action was compared to those of KbrO3 and wheat glutathione deshydrogenase (GSH-DHase). Firstly, the developed purification procedure of A. Niger SOX allowed to eliminate the catalase, the main contaminating activity present in the enzymatic sample. Kinetic studies have shown that SOX oxidised preferentially glutathione (GSH) and its activity was enhanced by cysteine (CSH). The second part of this work was to develop methods to quantify the oxidised and reduced forms of GSH and CSH. Thus, HPLC equipped with a coulometric or UV detector allowed the separation and simultaneous assay of GSH, CSH, GSSG, GSSC and CSSC. The 3 disulphides were also analysed by gel filtration with an UV detection. The comparison of the disulphide formation by the 3 different oxidising systems from mixtures of GSH and CSH was then investigated. While KbrO3 produces predominantly CSSC, SOX and GSH-DHase generated GSSG and GSSC, respectively. Lastly, enzymatic associations in model systems have been examined. When SOX is in the presence of GSH-DHase, both enzymes competed for the GSH consumption. The association of SOX and wheat germ peroxidase (POD) revealed that SOX was able to activate POD by producing H2O2. Thus, in dough, the use of SOX may influence oxidoreducing systems and consequently modify flour dough properties

Le bromate de potassium, additif a action lente, qui ameliore le volume des pains, la texture de la mie et augmente la tolerance au procede de panification, est aujourd'hui declare cancerigene. L'objectif de notre travail est d'etudier et de comprendre son mecanisme d'action afin de le remplacer par une ou plusieurs oxydoreductases. Une premiere partie de notre travail a consiste a determiner, en solutions aqueuses, les reducteurs presents dans la farine reagissant avec le bromate. Seuls les composes portant une ou plusieurs fonctions thiols sont oxydes par le bromate. La reaction avec la cysteine ou le glutathion a ete etudiee en detail (stchiometrie, produits, effet de differents parametres physico-chimiques). Cette etude a abouti a la mise en place d'un modele mathematique. Dans un second temps, nous avons etudie la reaction du bromate sur les thiols hydrosolubles en presence de farine (suspension de farine et pate). La vitesse de la reaction dans la suspension et dans la pate est ralentie par rapport a celle en solution aqueuse. En milieu pateux, une part plus importante des produits de l'oxydation de la cysteine est de degre d'oxydation superieur a ceux obtenus avec le glutathion. Par ailleurs, le bromate de potassium agit des le debut du petrissage mais, plus lentement, durant la phase de repos. Les effets rheologiques obtenus au cours du petrissage de pates realisees a l'aide du petrin experimental bioreacteur et au cours de la panification peuvent etre expliques par l'oxydation des thiols endogenes a la farine. La comparaison des vitesses d'action de differents oxydants (iodate, bromate, persulfate et chlorate de potassium) sur l'oxydation des thiols et sur leur effet rheologique confirme cette hypothese. Deux substituts enzymatiques ont ete proposes pour remplacer le bromate. L'un d'eux a fait l'objet d'une etude biochimique et rheologique similaire a celle du bromate (partie confidentielle, dont la publication est differee au 28 juin 2003).

Des agglomerats cationises de bromate de potassium ont ete etudies en spectrometrie de masse apres ionisation electrospray afin d'essayer de mieux comprendre les processus d'ionisation en solution, les phenomenes de desorption des ions en phase gazeuse a partir des gouttelettes chargees ainsi que leur stabilisation apres desolvatation. Les differents parametres qui, en phase liquide, peuvent conditionner la formation des agglomerats de sel cationises ont ete inventories : la concentration en sel, la nature et la teneur du solvant organique en solution, ainsi que le ph. Un modele issu de l'etat des connaissances de la gouttelette chargee a pu etre etabli : la distribution des etats de charge des agglomerats de sel cationises est dependante de la mobilite des ions dans la gouttelette. Les fragmentations induites par collision des agglomerats de sel cationises dans l'interface du spectrometre de masse ont permis de proposer un modele energetique pour rendre compte de la stabilite de ces ions en phase gazeuse. En fonction de la nature et de la teneur en solvant organique dans la solution, la desolvatation des ions dans l'interface est soumise a deux processus d'effets opposes. L'un releve des affinites cationiques en phase gazeuse, defavorables aux etats de charge eleves pour un solvant donne, l'autre est lie au processus de desorption qui peut leur etre favorable au travers de la solvatation. Il apparait egalement une stabilite particuliere pour certains nombres d'entites constitutives de l'agglomerat qui peut s'expliquer au travers des nombres magiques. L'etude des decompositions metastables de ces agglomerats de sel cationises a permis de mieux comprendre la stabilite de ce type d'ions en phase gazeuse. Il a ainsi ete demontre que differentes formes isomeres des agglomerats pouvaient coexister en solution.

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Devido aos inúmeros incentivos governamentais que impulsionam a produção do Biodiesel no mundo, tal combustível está sendo produzido largamente, e um fator preocupante frente a esse crescimento é o destino do glicerol excedente, já que seu uso é condicionado ao seu grau de pureza, que deve estar usualmente acima de 95%. No caso do glicerol bruto, resultante do processo de transesterificação do biodiesel, são necessários processos complexos e onerosos para que essa matéria-prima alcance as exigências em grau de pureza necessária para seu emprego. Além disso, os mercados tradicionais que o consomem (indústria de cosméticos, resinas, indústria farmacêutica, têxtil e alimentícia) têm uma capacidade limitada de absorção de quantidades maiores desse sub-produto. Sendo assim, esse trabalho tem como objetivo promover modificações estruturais na molécula do glicerol (comercial, alcalino e bruto), utilizando como agentes oxidantes os sais de bismuto (Zn(BiO3)2 e NaBiO3), NaClO e KBrO3/NaHSO3. As reações foram realizadas em ácido acético , ácido lático, acetona, água, com variação de tempo, temperatura, concentração dos reagentes e catalisadores. Essa metodologia sintética tem como finalidade gerar produtos com maior valor agregado tornando o glicerol um sub-produto mais reaproveitado e competitivo no mercado. Os melhores resultados na conversão do glicerol para os produtos mono, di e triacetilados foram alcançados utilizando 1mol% do catalisador NaBiO3 em diferentes concentrações de ácido acético glacial. Na ausência do catalisador a reação também ocorre, porém com tempo elevado. Em nenhum dos experimentos ocorreu à oxidação do glicerol. O modelo experimental realizado mostrou que é necessário excesso de ácido a fim de promover o equilíbrio na direção da conversão do glicerol e seletividade para os produtos mais valiosos comercialmente, o di e triacetilados.
Salvador

Single crystals of K(CN)$\sb{\rm x}$/(Br)$\sb{\rm 1-x}$ enriched in $\sp{15}$N have been studied by $\sp{15}$N NMR. Because of the anisotropic chemical shift, the NMR frequency spectrum of the orientational glass state reflects the distribution of cyanide orientations. By studying the spectrum at many orientations of each crystal, the orientational probability distribution function P($\Omega$) has been determined for x = 0.50 and for x = 0.20. The probability function is largest along the (100) directions, intermediate in the (110) directions, and nearly 0 along the (111) directions. The NMR determined P($\Omega$) is presented graphically and in terms of the Kubic Harmonic functions. The NMR results are in sharp contrast to molecular dynamics calculations but agree with neutron scattering data for x = 0.53.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Les travaux présentés dans ce manuscrit de doctorat s'inscrivent dans la thématique du stockage inter-saisonnier de l'énergie solaire thermique pour l'habitat et le tertiaire (eau chaude sanitaire et chauffage). Le stockage thermochimique en air humide est une des solutions les plus prometteuses, en particulier avec un réacteur à lit fixe. Le bromure de strontium et l'alun de potassium ont été sélectionnés comme réactifs pour leurs caractéristiques énergétiques lors de réactions d'hydratation et de déshydratation. L'étude est constituée d'avancées théoriques, de nombreuses expérimentations et d'un modèle numérique détaillé. Une étude thermodynamique a démontré l'existence d'une droite de charge qui relie les conditions d'entrée et de sortie de l'air humide au passage du réactif. Les équations régissant les réactions chimiques, les transferts massiques et thermiques et la conservation de la quantité de mouvement ont été établies et un modèle numérique monodimensionnel couplant ces phénomènes a été développé. Des essais sur différents échantillons des deux sels et pour divers conditions opératoires ont été effectués dans le but de comprendre les phénomènes physico-chimiques ainsi que pour valider l'étude théorique et le modèle numérique
This PhD thesis focuses on seasonal solar thermal energy storage for household applications such as production of heat and domestic hot water. Thermochemical storage was chosen for that purpose. The specific solid/gas reactions with water vapor, also called hydration/dehydration reactions, were used with a multi-scale global approach. The level of the reactor was identified as the critical level of that multi-scale approach. As a consequence, the integrated fixed-bed reactor technology in a moist air open loop system was adopted. A theoretical, experimental and numerical methodology was used for the study where strontium bromide and potassium alum salts were chosen as reactive materials. The corresponding reactions are: + 5 (H2O) ↔ (with Δhr=67.4 kJ/molwater and Δsr=175 J/K.molwater) + 9 (H2O) ↔ < KAl(SO4)2.12H2O > (with Δhr=44.2 kJ/molwater and Δsr=109.8 J/K.molwater) The first salt exhibits very good thermochemical properties. On the other hand, the main advantages of potassium alum are its low cost and the fact that it presents no sanitary risk. More than 30 cycles with 3 different samples of potassium alum and more than 25 cycles with 4 samples of strontium bromide under various stationary and dynamic operating conditions were carried out in order to understand the phenomena. The main experimental results were the following ones: • A very good stability and reproducibility of physical and chemical phenomena was observed for both materials. • A thermal reaction front was also observed. • A thermal hysteresis for both salts was found. • Based on that last observation a theoretical equation named charge-discharge line was developed. Experimental results with both salts validate the charge-discharge line theory. • A correlation between reaction kinetics, temperature rise due to the reaction, power of the reaction and the operating conditions was observed. The criterion for that correlation is the affinity of the reaction. A proportional correlation between affinity and reaction kinetics, temperature rise and power of the reaction was observed. • Spontaneous hydration and over-hydration reactions do not produce any particular difficulties or problems. • Pressure drop through the reactor and evolution of salts volume were also measured. Experimental energy density was measured in the range of 350 kWh/m3 for strontium bromide and 240 kWh/m3 for the potassium alum. • In general, strontium bromide is a very good candidate material for seasonal storage, while potassium alum cannot provide satisfying temperature rise and power. The equations governing those phenomena were also established and used to develop a 1D numerical model with partial differential equations coupling chemical phenomena, mass and thermal transfer phenomena and momentum conservation. Verification, validation and confirmation of this model under a very large range of operating conditions were carried out based on the experimental results of strontium bromide. A total of 19 different test cases were studied in order to validate the numerical model. The effect of humidity, temperature, quantity of reactive material and air flow were studied both for stationary and dynamic conditions. The numerical model was able to provide very satisfying results

Déduction de relations théoriques générales liant dans les systèmes liquides diphasés, les grandeurs observables "globales" aux grandeurs "locales" dans les différentes phases. Exposé de définitions et de notions thermodynamiques. Etablissement de relations générales pour les grandeurs molaires partielles. Etudes du cas d'un système réel : bromures d'alkyltrimethylammonium en milieu eau-kcl, qui montre que les solutions micellaires en milieu salin concentré peuvent être considérées comme un système diphasé. Données sur le partage d'un soluté moléculaire aniline en milieu micellaire. Etudes des volumes molaires partiels des constituants d'une microémulsion, etc. . .

博士
國立臺灣大學
毒理學研究所
88
Although the clinical intoxication from the abuse of cinnabar (a natural occurring HgS) and Ba Paul San have been reported, their neurotoxicological mechanisms are still not known. Thus, we attempted to comparatively study their neurotoxicological effects on the vestibular ocular reflex (VOR) system of guinea pigs. The commercial compounds were orally administered (1.0 g / kg/ bw) to guinea pigs once every day for consecutive 7 days. The results obtained showed that HgS at a dose of 1.0g/kg induced a reversible caloric hyperfunction (40% appearance) and irreversible hypofunction pattern (20% appearance) of caloric test. Similar to HgS, cinnabar-B (low lead) also induced similar caloric dysfunction, while cinnabar A (high lead) and PbCl2 profoundly produced caloric hyperfunction and hypofunction. Moreover, Ba Paul San-A and -B severely caused 50% of caloric hypofunction and 50% of no response. Monitoring the Hg contents of whole blood and cerebellum revealed that an increase in Hg contents was correlated with their neurotoxicological effects on VOR system, indicating that the inorganic and insoluble form of HgS or cinnabar could be absorbed from the gastrointestinal tract and detectable in the brain. Although morphological studies showed intact contour in the vestibular labyrinth, the enzymatic Na+/K+-ATPase activity of cerebellum was significantly inhibited by the HgS, cinnabar-A and Ba Paul San-A. Moreover, NADPH-diaphorase activity and cerebellar nitric oxide production also significantly increased. These findings suggest that the decreased Na+/K+-ATPase activity and the increased nitric oxide level in the cerebellum may be responsible for inducing dysfunctions of VOR system in guinea pigs treated with HgS and cinnabar. Neurotoxicity of mercury sulfide in the vestibular ocular reflex system of guinea-pigs A traditional Chinese mineral medicine Cinnabar, naturally occurring mercuric sulfide (HgS) is still occasionally prescribed, but the neurotoxic effects of HgS has not been elucidated. In this paper, an animal model of the purified HgS intoxication was established in guinea pigs in order to study neurotoxicity and pathophysiology of the vestibular ocular reflex system (VOR). Guinea-pigs were dosed with HgS by gastric gavage (0.01, 0.1 and 1.0 g /kg/day) for consecutive 7 days. By means of caloric testing coupled with the electronystagmo- graphic (ENG) recording in guinea-pigs, we have found that HgS at a dose of 0.1g/kg induced reversible caloric hypofunction pattern and at a higher dose of 1.0g/kg induced irreversible hypofunction of caloric test. Monitoring the mercury contents of various tissues (blood, kidney, liver and cerebellum) by continuous flow and cold vapor atomic absorption spectrometry (AAS) revealed that a certain amounts of HgS could be absorbed from the gastrointestinal tract and detectable in these tissues. In addition to the induced dysfunction of VOR system, HgS also caused disturbance of motor performance in guinea-pigs. In enzyme assay, Na+/K+-ATPase activity of cerebellum was also significantly inhibited by HgS. Morphological studies showed that partial cell lose only in the cerebellar Purkinje cells layer, but not in the granule cell layer, neither in the vestibular labyrinth. All of these findings suggest that cerebellar Purkinje cells are the sensitive target site responsible for HgS inducing dysfunctions of both VOR system and the motor performance in guinea-pigs. Thus, it is concluded that caloric test coupled with ENG recording in VOR system are certainly a sensitive biomarker for monitoring the neurotoxicity of HgS. Abnormal auditory brainstem responses in mice treated with mercurial compounds: Involvement of excessive nitric oxide In this paper, we attempted to establish a mouse model for monitoring oto-neurotoxicity of mercurial compounds. Mice were dosing with the sublethal doses of HgS (0.1 and 1.0g/ kg) or MeHg (0.2, 2.0 and 10mg/kg) by gastric gavage for consecutive 7 days. Analysis of the hearing threshold indicated that MeHg (2.0 or 10 mg/kg) can significantly elevated the threshold but MeHg (0.2mg/Kg) and HgS (0.1 or 1.0g/kg) can not. Recordings of auditory brainstem responses (ABR) showed that either MeHg- or HgS-treatment induced a significant prolongation of wave I-V and the interwave latencies. This ototoxicity of MeHg persisted even after 11 weeks discontinuous administration but that of HgS completely restored after 5 weeks discontinuous administration, which were intimately correlated with the disposition of Hg in the brain tissues. Moreover, the inhibition of Na+/K+-ATPase activity and nitric oxide overproduction in the brainstem are apparently related with the observed oto-neurotoxicity. Based on these findings, we conclude that the functional disturbance of brainstem induced by mercurial compounds may account, at least in part, for their oto-neurotoxicity. Neurotoxicity and tissue Hg contents in rats induced by mercuric sulfide and methyl mercury In this study, we compared the absorption, tissue Hg contents and neurotoxicity of two mercurial compounds, methyl mercury (MeHg) which is soluble and organic, and mercuric sulfide (HgS) which is insoluble and inorganic. Since HgS is naturally found in cinnabar, a substance used in Chinese mineral medicines, and relatively lacks of toxicology information, it is important for us to investigate its toxic effects. Both compounds were administered orally to male rats for 5 and 14 days with assays conducted at these times as well as 14 days after discontinuous administration. Neurotoxicity was assessed using five neurophysiological and neurobehavioral parameters. The results obtained showed that MeHg (2.0mg/kg) prominantly caused reduction (35% as compared to initial) of motor nerve conduction velocity (MNCV), prolongation (240% as compared to initial) of tail flick responses, incomplete restoration from the suppressive muscle action potentials, impairment of rota-rod motor performance (decrease 77%) effects and inhibition of Na+/K+-ATPase activity of sciatic nerve; The latter three toxicities were relatively irreversible. By contrast, the former three toxic effects of HgS were rather unremarkable and the latter two toxic effects were moderately and reversibly. The blood Hg levels were found to be correlated with the degree of toxicities of these two Hg compounds. These findings indicate that the insoluble HgS can still be absorbed from gastro-intestinal (G-I) tract and distributed in various tissues including the brain which is correlated with the observed toxities. The differential profile of neurotoxic potencies and reversibility of these two Hg compounds in this rat model provides us a better understanding on the toxicokinetics of HgS (an ingredient occasionally prescribed in Chinese mineral medicine). It is estimated that the toxic effect of HgS is ranging about one thousandth or less than that of MeHg. Prevention of pentobarbital tolerance by mercuric compounds in mice: Inhibition of Na+/K+-ATPase activity involved Prevention of Pentobarbital Tolerance by Mercuric compounds in Mice: Inhibition of Na+/K+-ATPase Activity Involved.The purpose of this study is to explore the possible mechanism of hypnosis-enhancing effect of HgS or cinnabar (a traditional Chinese medicine containing more than 95% HgS) in mice. Whether the component of Hg or sulfide is essential for their effects, the conventional methyl mercury (MeHg), NaHS and ZnS were used for comparative study. The main finding of this study is that a short period (7 days) of administration to mice with a nontoxic dose of mercurial compounds (HgS or cinnabar) and sulfide (NaHS or ZnS) not only significantly enhanced pentobarbital-induced hypnosis but also prevented tolerance induction after 7-day administration of pentobarbital. Furthermore, 10- and 35- days after the last administration of mercurial compounds and pentobarbital, the hypnotic response to pentobarbital restored normally in the control groups and the enhancing hypnotic effect of mercurial compounds still sustained. These effects of mercurial compounds correlated their accumulation in the brain and apparently related with the decrease in Na+/K+-ATPase and Ca2+-ATPase activities in the cerebral cortex. Further experiment indicated that mercuric compounds can decrease the blood nitric oxide which may be involved in the process of hypnosis-enhancing effect. Taken together, these findings indicated that the mercurial compounds including cinnabar, exert a long-lasting enhancing hypnotic activity and the nontoxic ZnS is perhaps useful for delaying or preventing pentobarbital-tolerance. Effects of methyl mercury, mercuric sulfide and cinnabar on active avoidance responses, Na+/K+-ATPase activities and tissue mercury contents in rats This study compared neurobehavioral toxicities of three mercurial compounds: methyl mercury (MeHg) is soluble and organic, while mercuric sulfide (HgS) and cinnabar (naturally occurring HgS) are insoluble and inorganic. Cinnabar, one of Chinese mineral medicine, is still used as a sedative in some Asian countries with relatively lacks of toxicological information. These mercurial compounds were administered intraperitoneally (MeHg, 2 mg/kg) or orally (HgS and cinnabar, 1.0 g/kg) to male rats once every day for consecutive 13 days with assays conducted during or after discontinuous administration for 1h, 2, 8 and 33 weeks. Neurotoxicity was assessed by the active avoidance response and locomotor activity. The results obtained showed that MeHg and cinnabar prominently and irreversibly caused decrease of body weight, prolongation of latency for escape from electric shock, decrease of the percentage for conditioned avoidance response (CAR) from electric shock, impairment of spontaneous locomotion and inhibition of Na+/K+-ATPase activity of cerebral cortex. By contrast, HgS reversibly inhibited spontaneous locomotion and Na+/K+-ATPase activity. It is noted that HgS significantly decreased the latencies of escape from electric shock during administration period which lasted for 33 weeks after discontinuous administration. Since pretreatment of arecoline (cholinergic receptor agonist) but not fipexide (a dopaminergic receptor agonist) could significantly shorten the prolonged latencies for escape caused by MeHg and cinnabar, suggesting that the deficit in the active avoidance response perhaps, at least in part, mediated by the dysfunction of the cholinergic rather than dopaminergic system. Determination of Hg levels of the whole blood and cerebral cortex revealed that the tissue mercury content is highly correlated with the degree of neurobehavioral toxicity of these Hg compounds. These findings implicate that the insoluble HgS and cinnabar can still be absorbed from G-I tract and distributed to the brain. The possibility that contamination of other minerals in the cinnabar accounts for the greater neurotoxic effects than HgS is under investigation. Changes in vestibulo-ocular reflex induced potassium bromate and thioglycolate in guinea pigs Potassium bromate (KBrO3) is known to be an oxidizing agent that is used not only as a food additive, mainly in the bread-making process, but also as a neutralizer in hair curling set. The home permanent cold wave hair kits consist of the first solution, thioglycolate which changes the disulfide (S-S) bonds of hair keratins to S-H bonds and makes hair flexible, followed by oxidizing the S-H bond to orginal S-S bond by the second solution 2% KBrO3, thus stabilizing the curling of the hair. Although it has been shown that bromate poisoning could cause severe and irreversible sensorineural hearing loss as well as renal failure, the action mechanism of vestibulo-ocular reflex influenced by KBrO3 remains to be studied. By caloric test coupled with the electronystagmographic (ENG) recording, the results showed that KBrO3 (50mg/Kg, SC) induced reversible caloric hyperfunction (40% appearance) but especially caused irreversible hypofunction pattern (20% appearance) of caloric test while combined with thioglycolate (15mg/Kg, SC). Therefore, it is worth while to elucidate the sites of the toxic effects of KBrO3 on VOR systems. Our data also indicated that that KBrO3 combined with thioglycolate prominantly and irreversibly caused decrease of retention time on equilibrium rod and impairment of spontaneous locomotion, while no difference on Na+/K+-ATPase and Ca2+-ATPase activities of cerebellum. However, KBrO3 alone inhibited spontaneous locomotion and equilibrium performance were only found until consecutive 2 weeks treatment. In order to understand the mechinary underlying these neurobehavioral and enztmatic activities changes, we also studied the change in nitric oxide (NO) level and bromide ion content, revealed no difference between KBrO3 alone and KBrO3 combined with thioglycolate in the NO and bromide level of blood, however, the latter can significantly caused cerebellar NO overproduction. Base on our findings, we demonstrated that whether KBrO3 alone or KBrO3 combined with thioglycolate induce oto-neurotoxicity including central VOR disorder. Meanwhile, These findings suggest that the increased nitric oxide level in the cerebellum, may be in partial responsible for inducing dysfunctions of VOR system in guinea pigs treated with KBrO3 combined with thioglycolate. The detrimental effects of potassium bromate and thioglycolate on auditory brainstem response of guinea pigs Although it has been shown that bromate poisoning could cause severe and irreversible sensorineural hearing loss as well as renal failure, the action mechanism of bromate-induced oto-neurotoxicity especially its combination with thioglycolate remains to be studied. In this study, we attempted to investigate the toxic effects of KBrO3 in combination with or without thioglycolate on the auditory brainstem response (ABR) system in the guinea-pigs which was claimed to be very susceptible to the xenobiotics. In a preliminary test, we have found that after consecutive 2 weeks administration, KBrO3 caused a significant prolongation of wave I-III and the interwave latencies of ABR as well as significantly elevated the threshold of hearing, suggesting that the conduction velocity of the peripheral auditory nerve was delayed. By contrast, the absolute latency of wave IV/V and the interwave latency of wave III-V were not significantly prolonged, suggesting that KBrO3 had no effect on the brainstem. This oto-neurotoxic effect of KBrO3 was markedly enhanced by combining with thioglycolate. Our data also indicated that KBrO3 combined with thioglycolate but not KBrO3 alone prominantly caused a decrease of body weight. However, enzymatic actitivies (including Na+/K+-ATPase and Ca2+-ATPase) and the level of nitric oxide (NO) have not seen significantly affected on the brainstem. Based on these findings, we tentatively conclude that whether KBrO3 alone or KBrO3 combined with thioglycolate induced oto-neurotoxicity majorly through the peripheral neurons system rather than via central brainstem intoxication.

The abundance and low fat content of Pacific whiting support Its use for the production of surimi. The degradation of muscle proteins by myxosporidian secreted proteinase(s) has been associated with its soft texture. High residual activity is retained through the washing process used in the production of surimi and precludes the formation of a strong heat-set gel by surimi sols. Physical, chemical and SDS-PAGE analysis defined the reinforced oxidation of free sulfhydryl groups on myofibrillar proteins to disulfide bonds by potassium bromate. SDS-PAGE demonstrated myosin degradation during heat-setting and the protection of myosin from protelnase attack by bromate. A level of 0.075% bromate Inactivated 89.87% of the total proteinase activity in sols. It was assumed that cysteine proteinases were Inactivated and residual activity was associated with proteinases with a serine active site. Major iraprovement in gel coheslveness and elasticity was observed at bromate levels [less than or equal to] 0.075% with only a slight improvement at higher levels. Maximum hardness was observed at 0.150% with no (P>0.050) increase at higher levels. Brittleness was improved (P>0.050) by bromate levels [greater than or equal to] 0.100%; no maximum degree of brittleness was observed within the range ([less than or equal to] 0.250%) of concentrations investigated. An optimum folding test grade of AA was achieved by a minimum of 0.150% Potassium bromate improved gelling characteristics of sols of Pacific whiting surimi through proteinase inactivation and reinforced disulfide formation during heat-setting. Improvement in cohesiveness and elasticity was primarily a function of proteinase inactivation. Maximum hardness and brittleness required additional oxidative capacity which was not fully required for an optimum folding test grade.
Graduation date: 1989

A beam of oriented CF(,3)Br molecules is prepared by passing a randomly oriented beam through an appropriate series of inhomogeneous and homogeneous electric fields. An atomic K beam crosses the beam of oriented CF(,3)Br and the angular distribution of the reactively scattered KBr is measured with a differential surface ionization detector. The "heads" orientation (Br end closest to the incoming K) is about three-fold more reactive than the "tails" orientation. The KBr is scattered backwards in the "heads" orientation and forward in the "tails" orientation, qualitatively consistent with a "harpoon" type of mechanism in which the orientation affects either the electron jump or the breakup of the dissociating negative ion. A new apparatus has been constructed which uses a seeded supersonic nozzle source to produce the oriented molecular beam. The new source is characterized by measuring the velocity distributions of various seeded beams using the time-of-flight technique. The state-selecting properties of the inhomogeneous hexapole field are characterized by measuring the transmission of the field for seeded beams of CF(,3)Br, CF(,3)I, and CH(,3)Cl.

Simultaneous optical and acoustic information was used to elucidate the mechanism that causes acoustic emission (AE) during growth of potassium bromide (KBr) crystals. The generation mechanism postulated here is one of inter-crystal interaction. AE was used to monitor the growth of different crystal structures of KBr grown with varying degrees of lead (Pb) dopant (0-32000 ppm). Digital images were collected simultaneously at magnifications up to x75. Integrated AE profiles and image whitening curves were calculated. Best agreement between these was found for the crystal growth of the dendritic form of KBr (4080-8120 ppm Pb dopant), and the doped forms of 12210 ppm Pb and above. The dendritic form of KBr observed between 4080 and 8120 ppm Pb consisted of finger-like needles that grew outward from the crystallizing solution. Scanning electron microscopy showed these fingers to consist of contiguous chains of tiny (< 25 μm dia.) octahedra. This microscopic structure provided many potential sources of emission. The total AE observed per gram of crystals produced during the growth of the different KBr morphologies was found to vary in a reproducible manner over 60 experiments. The dendritic form of KBr exhibited 10 times the acoustic emission per gram of crystals produced compared with the undoped (cubic) form. The mass of crystals grown for individual experiments was 0.004-0.212 g. AE was able to reliably follow the growth of these very small masses of crystals whose morphologies consisted of clusters of crystals in intimate contact. A confirmatory mechanistic study was carried out using ammonium chloride (NH₄Cl) which is known to produce classic dendritic growth. In contrast to the clusters of tiny microcrystals observed for the dendritic form of KBr, one would not expect the growth of the single crystal branches of NH₄Cl to exhibit acoustic emission, as there is no means to generate AE by the inter-crystal interaction mechanism. Single branch fracture is possible but rare. Experimental results showed very limited emission from NH₄Cl, and thus supported the hypothesis of inter-crystal interaction. Primary nucleation could not be detected acoustically. The end of crystal growth was acoustically determinable. The AE associated with the growth of the dendritic form of KBr finished abruptly when the maximum image whiteness was reached. The acoustic waveforms detected during the growth of the KBr morphologies were compared with artificially produced signals of bulk fracture and crystal impact. Acoustic waveform analysis showed these classes of signals to be distinguishable.

The photoexcitation spectra of transition region species formed in bimolecular reactions of K + NaX (X = Cl, Br, I) have been observed by measuring the intensity of sodium D line emission at 589.0 nm as a function of excitation wavelengths between 595 and 640 nm. The portion of the spectrum measured for the K + NaCl system is qualitatively similar to that previously observed by Magurie, et al (MAG86). The spectra obtained for the K + NaBr and NaI systems are significantly different than that of the K + NaCl system, and show a distinct feature centered at approximately 610 nm, and indicate that the reaction dynamics are quite different for the heavier sodium halide systems. The results of classical trajectory calculations performed using K + NaCl potential energy surfaces suggest that the structure in the K + NaBr and K + NaI spectra is not due to a mass effect; but rather from unique features of the potential energy surfaces for these reactions which are, as yet, unknown. Because of insufficient theoretical and experimental information, interpretation of these results in terms of the dynamical processes in these reactions is not yet possible. However, several different possible mechanisms of this structure are discussed which can be experimentally tested. Results of proposed future experiments should be able to provide the necessary information to understand the nature of these spectra.