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1
Ping-guo, Zou, Zhang Zhen-tao, and Li Gang. "Research on the Influence of Steam Turbine Seal Leakage." E3S Web of Conferences 248 (2021): 01014. http://dx.doi.org/10.1051/e3sconf/202124801014.
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CFD was employed to simulate the steam flow in 1.5-stage cascades with three different seal clearances. When the seal clearance is 0, there is no steam seal leakage, no obvious secondary flow in the cascade, and the stage efficiency reaches 88.27%. When the clearance of diaphragm seal and rotor tip seal is 1mm, the leakage of diaphragm seal strongly interferes with the flow in the cascade, which promotes the formation and development of the end-wall secondary flow near rotor hub, and the rotor tip leakage flow has little effect on next stage, and the stage efficiency drops by about 2 percentage points. When the seal clearance is 4mm, the end-wall secondary flow near rotor hub and next stator casing is strengthened significantly, and the attack angle loss increases, so the stage efficiency decreases by about 13 percentage points.
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Alwan, Salih K., Akbar Arabhosseini, Mohammed H. Kianmeher, and Ali M. Kermani. "The Effect of Clearance on the Performance of Machine Husking Rubber Rolls for Two." JOURNAL OF UNIVERSITY OF BABYLON for Pure and Applied Sciences 26, no. 3 (2018): 207–14. http://dx.doi.org/10.29196/jub.v26i3.595.
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The effect of clearance between cylinders of machine husking rubber rolls (type Yanmar rubber roll – ST 50) on rice husk quality and breakage percentage was evaluated for two cultivars of rice. Tarm Hashemi (TH) and Daillman (DM) and clearance between cylinders of machine husking rubber at three different levels of 0.4, 0.6 and 0.8mm.The experiment was done in factorial experiment under complete randomized design (CRD) with three replications the results indicate that the TH cultivar is significantly better than the D M in all studied traits. There was a negative relationship between increased clearance with head rice percentage and brown rice percentage in addition to the positive relationship between the increased percentage of cracked grain ,broken rice percentage and husking efficiency.
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LOOH, George Ashwehmbom, Fondzenyuy Cedric MANGEH (III), Xunwei WANG, and Xiushan WANG. "Performance Assessment of a Self-propelled Paddy Grain Thresher under Different Threshing Functional Parameters." Applied Engineering in Agriculture 36, no. 2 (2020): 141–49. http://dx.doi.org/10.13031/aea.13585.
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HighlightsThis research was aimed at assessing the performance of a self-propelled paddy grain thresher.Increasing cylinder speed increased the threshing percentage and percentage of broken grains of the machine.More broken grains were obtained at a lower concave clearance.The feed rate did not have much significance on the performance parameters that were evaluated. Abstract.This research was conducted to assess the performance of a self-propelled mini combine harvester, model number 4LZ-0.8 under different threshing functional parameters such as cylinder speed, concave clearance, and feed rate. An indoor experiment was conducted using the mini combine with an axial flow threshing cylinder and tangential feeding of material. These functional parameters were set at 5 levels each. The responses were obtained in terms of threshing percentage, percentage of unthreshed grains and percentage of broken grains. Response values were analyzed using the response surface tool (rstool) in MATLAB. Analysis of variance was done to determine the significant effects of the factor variations on the response values. MATLAB was used to present response surface graphs that were used to describe the variations of the responses as the factors changed from one level to the other. Results showed that with an increase in cylinder speed from 697 to 1202 rpm, the percentage of broken grains increased significantly from 0.0384% to 3.4052%, respectively. At cylinder speeds of 697 and 1202 rpm, the percentage of unthreshed grains increased from 0.1515% to 0.2162%, respectively. Furthermore, an increase in feed rate decreased the threshing percentage. The highest threshing percentage was obtained at an average concave clearance of 27 mm. Furthermore, it was realized that increasing the concave clearance from 18 to 35 mm, equally increased the percentage of unthreshed grains from 0.1478% to 0.3177%. The percentage of grain damage decreased from 3.2758% to 0.0268% with an increase in concave clearance from 18 to 35 mm, respectively. From the results obtained, it was tested and suggested that operating the threshing cylinder at a cylinder speed of 1100 rpm, concave clearance of 27 mm and feed rate of 0.9 kg s-1 offered the best machine performance. At these suggested values of the operating parameters, the threshing percentage was 99.9801%, the percentage of broken grains was 0.0134%, and the percentage of unthreshed grains was 0.0199%. Keywords: Assessment, Axial threshing unit, Cylinder speed, Concave clearance, Feed rate, Functional parameters, Threshing percentage.
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Krawiec, Donald R., Robert R. Badertscher, A. Robert Twardock, Stanley I. Rubin, and Howard B. Gelberg. "Evaluation of 99mTc-diethylenetriaminepentaacetic acid nuclear imaging for quantitative determination of the glomerular filtration rate of dogs." American Journal of Veterinary Research 47, no. 10 (1986): 2175–79. https://doi.org/10.2460/ajvr.1986.47.10.2175.
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SUMMARY Thu suitability of 99mTc-diethylenetriaminepentaacetic acid (99mTc-dtpa) as an agent to assess glomerular filtration rate (gfr) in dogs was evaluated. Glomerular filtration rates of 12 healthy dogs were determined on the basis of creatinine and/or inulin clearance. Glomerular filtration rates also were determined in 7 dogs after induction of acute renal failure by administration of amphotericin B. The healthy dogs and the amphotericin B-treated dogs were given 99mTc-dtpa (1 to 2 mCi) iv. The percentage of the 99mTc-dtpa dose in the kidneys (percentage dose) was determined, with background activity subtracted from total activity at 15-s intervals 0 to 6 minutes after 99mTc-dtpa infusion. Linear regression analyses (lra) were performed to determine whether the percentage dose at various time intervals after injection correlated with gfr calculated on the basis of creatinine and inulin clearance data. One to 3 minutes after 99mTc-dtpa administration appeared to be the best period for analysis of the data. The percentage dose of 99mTc-dtpa (corrected for kidney depth differences) was determined and lra against gfr were performed. The percentage dose correlated better with inulin clearance (r = 0.94) than with endogenous creatinine clearance (r = 0.83). Only inulin clearance correlations improved with kidney depth correction. The lra was used to derive an equation that could be used to calculate gfr on the basis of the percentage dose. The equation derived from inulin regression was: gfr (milliliter/minute/kilogram of body weight) = 0.194 (depth-corrected percentage dose) − 0.37; the equation derived from the creatinine regression was: gfr (milliliter/minute/kilogram) = 0.171 (depth-corrected percentage dose) − 0.15. Therefore, 99mTc-dtpa can be used as an agent for the rapid, noninvasive, and accurate determination of gfr in dogs.
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Adiele, DF. "Serious crime in Nigeria: an empirical analysis using time series data (between 2000-2010)." Global Journal of Mathematical Sciences 12, no. 1 (2015): 25–29. http://dx.doi.org/10.4314/gjmas.v12i1.14.
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This paper empirically examined the effect of the clearance rate, the unemployment rate, the percentage of females in employment and the percentage of the labour force with tertiary education on Serious Crime in Nigeria for the period 2000-2011. Time-series data from (NBS) National Bureau of statistics and Nigeria police annual reports 2011are used and tests for the existence of a long runcointegration relationship among serious crime, clearance rate and various socio economic indicators is carried out. The cointegration analysis provides strong evidence of the existence of a long-run model. With the normalized coefficients showing a negative effect of the clearance rate, percentage of females in the labourforce and the percentage of the labour force with tertiary education on serious crime, with the exception being the unemployment rate which is found to exert a positive effect.KEYWORDS: Crime, Cointegration, Unit Root, Time-Series.
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Baud, Frédéric J., Pascal Houzé, Jean-Herlé Raphalen, Pascal Philippe, and Lionel Lamhaut. "Vancomycin Sequestration in ST Filters: An In Vitro Study." Antibiotics 12, no. 3 (2023): 620. http://dx.doi.org/10.3390/antibiotics12030620.
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Background. Sequestration of vancomycin in ST® filters used in continuous renal therapy is a pending question. Direct vancomycin-ST® interaction was assessed using the in vitro NeckEpur® technology. Method. ST150® filter and Prismaflex dialyzer, Baxter-Gambro, were used. Two modes were assessed in duplicate: (i) continuous diafiltration (CDF): 4 L/h, (ii) continuous dialysis (CD): 2.5 L/h post-filtration. Results. The mean initial vancomycin concentration in the central compartment (CC) was 51.4 +/− 5.0 mg/L. The mean percentage eliminated from the CC over 6 h was 91 +/− 4%. The mean clearances from the CC by CDF and CD were 2.8 and 1.9 L/h, respectively. The mean clearances assessed using cumulative effluents were 4.4 and 2.2 L/h, respectively. The mean percentages of the initial dose eliminated in the effluents from the CC by CDF and CD were 114 and 108% with no detectable sequestration of vancomycin in both modes of elimination. Discussion. Significant sequestration adds a clearance to that provided by CDF and CD. The study provides multiple evidence from the CC, the filter, and the effluents of the lack of an increase in total clearance in comparison with the flow rates without significant sequestration in the ST® filter comparing cumulative effluents to the initial dose in the CC. Conclusions. There is no evidence ST® filters directly sequestrate vancomycin.
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Walsh, Donald, M., and Henry D. Royal. "Evaluation of a single injection of 99mTc-labeled diethylenetriaminepentaacetic acid for measuring glomerular filtration rate in horses." American Journal of Veterinary Research 53, no. 5 (1992): 776–80. http://dx.doi.org/10.2460/ajvr.1992.53.05.776.
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Summary Glomerular filtration rate (gfr) was measured in 12 clinically normal horses, using the standard inulin clearance method, and values were compared with values for 2 methods, using a single rapid iv injection of 99mTc-la-beled diethylenetriaminepentaacetic acid (99mTc-dtpa). The first 99mTc-dtpa method used a 2-compartment model to calculate gfr blood clearance of the tracer. The second method used sequential digital gamma camera images of the kidneys to determine fractional accumulation of the total dose of the tracer in the kidneys (percentage of injected dose, gamma camera) from 0 to 10 minutes after radionuclide administration. Linear correlation among the 3 methods was determined. Mean (± SD) gfr, using the inulin clearance method, was 154.67 ± 42.28 ml/min/100 kg of body weight. Mean gfr, using the 2-compartment blood clearance curve, was 146.92 ± 27.49 ml/min/100 kg. Mean gfr, using percentage of injected dose (gamma camera method) was 154.7 ± 22.00 ml/min/100 kg. The percentage of injected dose (gamma camera method) did not correlate significantly to the inulin clearance results. However, a significant (r = 0.666, P < 0.018) correlation was observed between the inulin method and the 99mTc-dtpa blood clearance method. Significant (P < 0.0001) difference also was observed in the split function of the equine kidneys, with gfr of the right kidney contributing 60.1 ± 9.12% of the total function, as determined by 99mTc-dtpa gamma camera imaging. Because the 99mTc-dtpa blood clearance method does not require urine collection, it may be a more practical procedure to measure gfr in the horse.
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Al-Dola, ayoob. "Evaluation the performance of the locally Developed Corn Thresher Machine from Manual to Mechanical System." Kirkuk University Journal For Agricultural Sciences 14, no. 2 (2023): 54–66. http://dx.doi.org/10.58928/ku23.14205.
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This study was conducted to develop corn thresher located in the College of Agriculture and Forestry, University of Mosul - Iraq in 2022, and this thresher operated by manual system. 1The factors were studied using two varieties of corn (Rayal, ZP), rotation speed 50, 100 rpm, and clearance between threshing wheel and pressing plate 10, 20 mm on some indicators, namely: productivity (kg.h-1), percentage of damaged grains (%), percentage of non-threshed grains (%).Operating costs (dinars. kg-1), the experiment was implemented according to a Complete Randomized Design (CRD), and with three replications .The main objectives of the study were to develop a manual system of thresher machine and to select the most appropriate operating factors that affect its performance. The results of the study showed that the (Rayal) variety was superior to the (ZP) variety in recording the lowest percentage of damaged grains. The rotation speed 100 rpm achieved the highest productivity values and the lowest values for each of (percentage of non-threshed grains, Operating costs), The clearance 20 mm was superior in achieving the highest values for productivity and the lowest values for the percentage of damaged grains, while the clearance 10 mm achieved the lowest values for the percentage of non-threshed grains.
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Genetzky, R. M., F. V. Loparco, and A. E. Ledet. "Clinical pathologic alterations in horses during a water deprivation test." American Journal of Veterinary Research 48, no. 6 (1987): 1007–11. https://doi.org/10.2460/ajvr.1987.48.06.1007.
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SUMMARY A 72-hour water deprivation test was performed in 12 horses to determine clinical pathologic changes. Reference values for electrolyte (X) clearance, expressed as a percentage of creatinine clearance (clCR; %clCRX), were also determined. A comparison was made between urine concentration measurement techniques. Results of %clCRX determination in 12 horses before water deprivation were 0.034 ± 0.095 %clCRNa, 42.4 ± 9.8 %clCRK, 0.352 ± 0.190 %clCRCl, and 0.710 ± 0.250 %clCRP. During water deprivation, there was individual variation for electrolyte clearances, but Na excretion increased significantly (P < 0.01) at 24 and 48 hours. After 48 hours’ water deprivation, %clCRNa decreased significantly, but was still greater than the initial clearance. Plasma protein was a better indicator of water deprivation (dehydration) in the horse than was pcv. Electrolyte concentrations in serum and urine were determined. Little significant (P < 0.01) change in acid-base values was noticed after 72 hours’ water deprivation. Urine osmolality (as determined by osmometry) was compared with sp gr (determined by refractometry) in determining urine concentration. Initially, sp gr correlated well with urine osmolality determinations, but this correlation decreased after 48 hours.
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N K Bansall and Shiv Kumar Lahan. "Design and Development of an Axial Flow Thresher for Seed Crops." Journal of Agricultural Engineering (India) 46, no. 1 (2009): 1–8. http://dx.doi.org/10.52151/jae2009461.1357.
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An axial flow thresher was designed and developed to maintain the seed quality of major oil seed and pulse crops. Major features of the thresher are minimum injury to seed, higher seed recovery and good seed quality, easy feeding and less fatigue to labour. The cylinder speed and aspirator speed are independent and very convenient to vary as per seed size. It has provision of easy adjustment of concave clearance, sieve clearance and slope of sieves. At optimum combination of cylinder sped and concave clearance at different seed moisture contents to thresh oilseeds and pulse crops, the performance parameters were within acceptable ranges of visible seed damage 12% and threshing efficiency 195% with threshed seed germination percentage of green gram (88%), black gram (90%), soybean (90%). chickpea (90%) and sunflower (86%). The germination percentages were above the minimum seed standards suggested by ISTA, (1999).
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Ali, Khaled Abdeen Mousa, Changyou Li, Han Wang, Ahmad Mostafa Mousa, and Marwa Abd-Elnaby Mohammed. "Enhancing the Performance of Sunflower Threshing Machines through Innovative Enhancements." Agriculture 14, no. 2 (2024): 312. http://dx.doi.org/10.3390/agriculture14020312.
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Improving the performance of the threshing process is of utmost importance in enhancing the quality of sunflower seeds and minimizing power consumption in sunflower production. In this study, we developed a modified sunflower threshing machine by incorporating two types of threshing rotors, namely the angled rasp bar rotor and the tine bar rotor, as compared to the round bar rotor. The performance of these rotors was evaluated under various rotational speeds (150, 200, 250, and 300 rpm) and concave clearances (10, 15, and 20 mm). The evaluation parameters included machine throughput, the specific energy of threshing, the percentage of damaged seeds, the percentage of unthreshed seeds, and threshing efficiency. The results indicate that the specific energy decreased with an increase in rotor speed and a decrease in concave clearance, with the tine bar rotor exhibiting the lowest values. Threshing efficiency showed an increasing trend with higher rotor speeds and reduced concave clearance. The modifications made to the rotor design resulted in an enhanced threshing efficiency, with an improvement from 96.30% to 97.93% achieved at a rotor revolving speed of 300 rpm and a concave clearance of 10 mm. Moreover, the specific energy consumption reduced from 9.65 kW·h/ton to 5.09 kW·h/ton under the same operational conditions. These findings highlight the efficacy of the novel rotor design modifications in optimizing the performance of the stationary sunflower threshing machine, leading to improved efficiency and reduced energy consumption in sunflower seed threshing operations. Given its performance characteristics, this machine exhibits potential suitability for sunflower farms of small to medium scale.
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Widdicombe, John. "Airway and alveolar permeability and surface liquid thickness: theory." Journal of Applied Physiology 82, no. 1 (1997): 3–12. http://dx.doi.org/10.1152/jappl.1997.82.1.3.
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Widdicombe, John. Airway and alveolar permeability and surface liquid thickness: theory. J. Appl. Physiol. 82(1): 3–12, 1997.—The thickness of airway surface liquid (ASL) can be calculated as the ratio of the permeability coefficient of an absorbed inert tracer to the percentage rate in which it decreases in content in the airway lumen. The percentage clearance of radiolabeled diethylenetriaminepentaacetic acid (DTPA) from human airways or lungs has been measured many times, with a mean value of 1.04 ± 0.25 (SD) %/min. Rates of clearance from animal lungs of most species give values of the same order, although they are lower in the sheep and higher in the dog. Permeability coefficients have not been measured simultaneously with percentage clearances and not at all for human tissues. Values for mannitol and sucrose, of which the former gives a permeability coefficient ∼25% greater than that for sucrose and DTPA in airway tubes and isolated mucosal sheets from experimental animals, give a mean of ∼7.1 × 10−7 cm/s. This corresponds to thicknesses of ASL of ∼20–150 μm for various species. The assumptions underlying this estimate are discussed. It is concluded that ASL thickness in vivo may be considerably greater than in vitro measurements involving rapid freezing of the airway wall. Estimates of alveolar permeability suggest that either it is very considerably lower than that of the airway epithelium, that methods to measure alveolar permeability mainly reflect airway permeability, or both.
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Reece, P. A., I. Stafford, R. L. Abbott, et al. "Two- versus 24-hour infusion of cisplatin: pharmacokinetic considerations." Journal of Clinical Oncology 7, no. 2 (1989): 270–75. http://dx.doi.org/10.1200/jco.1989.7.2.270.
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The disposition of unchanged cisplatin was compared after two- and 24-hour intravenous (IV) infusion to eight patients with germ cell cancer (dose, 100 mg/m2), 14 patients with head and neck cancer (dose, seven patients 50 mg/m2; seven patients, 100 mg/m2). Patients were randomized to receive either a two- or 24-hour infusion in the first course of treatment and the reverse in the second course. Cisplatin renal clearance, total clearance, and the percentage of the dose excreted unchanged in urine were significantly lower with the longer infusion. Total clearance was 345 +/- 97.0 mL/min/m2 after the two-hour infusion and 268 +/- 70.7 mL/min/m2 after the 24-hour infusion (P less than .0001). Renal clearance was 79.1 +/- 35.3 mL/min/m2 and 34.1 +/- 14.9 mL/min/m2 (P less than .0001). The percentage of the dose excreted unchanged in urine was 22.9 +/- 6.5% and 12.8 +/- 4.0%, respectively (P less than .0001). The ratio of cisplatin renal clearance to creatinine clearance was 1.95 +/- .96 after the two-hour infusion and .90 +/- .40 after the 24-hour infusion (P less than .001). There was only a poor relationship between cisplatin renal clearance and creatinine clearance after a two-hour infusion (r2 = .05, P greater than .1) or 24-hour infusion (r2 = .18, P greater than .05). The severity of emesis was graded on a four-point scale and was significantly less with the 24-hour infusion than with the two-hour infusion (P less than .05). Twenty-four-hour infusion of cisplatin resulted in greater drug retention in patients due to reduced renal clearance, but was also associated with reduced emetic toxicity, probably as a result of lower peak plasma levels.
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Alsharifi, Salih K. Alwan, Akbar Arabhosseini, Mohammad H. Kianmehr, and Ali M. Kermani. "Effect of Clearance on Mechanical Damage of Processed Rice." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 65, no. 5 (2017): 1469–76. http://dx.doi.org/10.11118/actaun201765051469.
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The effect of rubber rolls in husking machine (Yanmar type) on rice cultivars of Tarm Hashemi (TH) and Daillman Mazandarani (DM) were tested during husking at three clearances of 0.4, 0.6 and 0.8 mm between cylinders. The experiments were carried out in a factorial experiment under complete randomized design with three replications. The results showed that the TH cultivar was significantly better than the DM in all studied conditions. The results showed broken rice of 6.239 % and 6.729 %, cracked grain percentage of 3.787 % and 4.671 %, brown rice (husked rice) of 82.049 % and 80.113 %, husking efficiency of 84.719 % and 83.152 % and head rice yield of 70.633 % and 69.202 % for TH and DM, respectively. The clearance of 0.8 mm was significantly superior to the levels of 0.4 and 0.6 mm in all studied conditions.
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Zia, Aleena, Armisha Desai, Molly Tieman, and Haley Pritchard. "Assessing the association between cefepime percentage free trough level and neurotoxicity." Antimicrobial Stewardship & Healthcare Epidemiology 2, S1 (2022): s25. http://dx.doi.org/10.1017/ash.2022.100.
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Background: Cefepime has a known association with neurotoxicity due to its ability to cross the blood–brain barrier. The symptoms of neurotoxicity are highly variable. It has been postulated that cefepime neurotoxicity is associated with elevated levels of the drug. However, studies assessing for an association between serum drug level and the incidence of neurotoxicity have yet to establish a consistent threshold. We assessed serum cefepime levels and incidence of neurotoxicity to help develop a dosing strategy to minimize adverse effects. Method: In total, 32 inpatients admitted from January 2019 to November 2021 who received cefepime according to institutional standard dosing regimens for at least 72 hours were reviewed by infectious diseases pharmacists who obtained serum cefepime levels and performed pharmacokinetic analyses to obtain percentage free trough levels. Cefepime percentage free trough levels were defined as therapeutic if they were above the known minimum inhibitory concentration (MIC) of the treated organism and were <40 μg/mL. Patient charts were reviewed for clinical findings consistent with cefepime-induced neurotoxicity. Numerical and statistical analyses were performed to assess factors with a significant association with neurotoxicity. Results: Overall, 16 (47.1%) patients showed some evidence of neurotoxicity, 9 (56.3%) of whom had a likely alternate clinical cause of symptoms (Table 1). We did observe that patients with creatinine clearance <60 mL/min were more likely to have symptoms concerning for neurotoxicity. Conclusions: Cefepime percentage free trough levels were highly variable, and no association with neurotoxicity was observed. Patients with decreased creatinine clearance were significantly more likely to develop neurologic findings consistent with cefepime-induced neurotoxicity. Further study is needed to establish a relationship between cefepime pharmacokinetic values and incidence of neurotoxicity.Funding: NoneDisclosures: None
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Olanlokun, John Oludele, Janet Adenike Adetutu, and Olabode Olufunso Olorunsogo. "ln vitro inhibition of beta-hematin formation and in vivo effects of Diospyros mespiliformis and Mondia whitei methanol extracts on chloroquine-susceptible Plasmodium berghei-induced malaria in mice." Interventional Medicine and Applied Science 11, no. 4 (2021): 197–206. http://dx.doi.org/10.1556/1646.2020.00001.
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AbstractBackground and aimThis study was carried out to investigate antiplasmodial activities of Diospyros mespiliformis (DM) and Mondia whitei (MW) in Plasmodium berghei-infected mice.Materials and methodsAir-dried stem of DM and root of MW were soaked in methanol, decanted and concentrated to give extracts. Parts of these extracts were partitioned successively to give dichloromethane, ethylacetate and methanol fractions. Mice (18 ± 3 g) were infected with Plasmodium berghei-infected erythrocytes from a donor mouse and were treated with the extracts, while the drug control group received 10 mg/kg body weight of artesunate and the parasitized control received the vehicle (5% v/v DMSO). Percentage parasitemia and clearance were estimated from thin films of blood smear. Hematological parameters were determined using standard methods. Both extracts were also tested on in vitro inhibition of β-hematin formation.Results, discussion and conclusionResults showed that DM had the least percentage parasitemia (0.67%) and highest percentage parasite clearance (84.7%) while the MW had 0.89% percentage parasitemia and 79.7% clearance at the highest dose used after the seventh day relative to untreated control. The cell free antiplasmodial activity of the fractions and extracts of both DM and MW revealed that DM significantly inhibited β-hematin formation than MW. The packed cell volume, white blood cell count, Lymphocyte, Eosinophil, Monocyte and Neutrophil significantly increased in the treated groups compared with the control. The results showed that the DM had higher antiplasmodial activity.
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Al-Dawla, Ayoub Abdel Aziz Mohammed, and Adel Ahmed Abdullah Rajab. "Evaluation Analysis of Thresher Mechanically Developed." IOP Conference Series: Earth and Environmental Science 1213, no. 1 (2023): 012091. http://dx.doi.org/10.1088/1755-1315/1213/1/012091.
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Abstract This machine was developed in Al-Hamdani factory in the industrial area of Mosul city in 2022 and practical experiments were carried out to evaluate its performance. The factors were studied using two Cultivars of corn (Rayal and ZP) and rotation speed (50, 100) rpm And clearance (10-20) mm on some indicators, namely: productivity (kg.h−1), percentage of unseparated grains (%), consumed capacity (kilowatts) and operating costs (dinar.kw−1). The experiment was carried out using a Complete Random Design (CRD) and with three refiners specifically The main objectives of the research were to develop a manual threshing machine and to select the most appropriate operating factors that affect its performance. The results of the study showed the superiority of the (ZP) variety on the (Rayal) variety in recording the lowest power exhausted and the lowest costs of electrical energy. The rotational speed 100 rpm exhausted achieved the highest value for both productivity exhausted, capacity and electrical energy unseparated costs, while achieving 50 rpm has the highest value in the percentage of unseparated reaching superiority grains, as well as the clearance superiority 20 mm in achieving the highest productivity, the lowest reaching capacity for the energy consumed and the lowest costs, while clearance 10 gave the lowest percentage of the unseparated grains.
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Zahm, JM, M. King, C. Duvivier, D. Pierrot, S. Girod, and E. Puchelle. "Role of simulated repetitive coughing in mucus clearance." European Respiratory Journal 4, no. 3 (1991): 311–15. http://dx.doi.org/10.1183/09031936.93.04030311.
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The role of repetitive simulated coughing on the clearance of gel mucus simulant was investigated in vitro, by using a simulated cough machine. The repetition of cough induced a significant increase (p less than 0.01) in mucus simulant clearance (139.3 +/- 78.7 mm) in comparison to a single cough (24.9 +/- 27.5 mm). Moreover, the increase in frequency of the repetitive coughing induced a marked and significant increase in mucus simulant clearance (75.4 +/- 51.1 mm and 139.3 +/- 78.7 mm at 0.1 Hz and 1.6 Hz frequency, respectively). A significant (p less than 0.05) correlation was observed between the percentage increase of clearance and both shear-thinning index (r = 0.62) and the thixotropic index (r = 0.63). These results suggest that the shear-dependent properties of mucus, associated with a repetitive coughing, may increase the efficiency of mucus clearance by air flow mechanisms.
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Burlingame, R. W., M. A. Volzer, J. Harris, and T. W. Du Clos. "The effect of acute phase proteins on clearance of chromatin from the circulation of normal mice." Journal of Immunology 156, no. 12 (1996): 4783–88. http://dx.doi.org/10.4049/jimmunol.156.12.4783.
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Abstract The clearance of nucleosome core particles and H1-stripped chromatin from the circulation of mice was examined. Radiolabeled chromatin preparations were injected into mice, and blood samples were obtained over 60 min. The animals were then killed, and the selected organs were collected and radioactivity was measured. The acute phase response (APR) was induced by i.p. injections of casein before some clearance studies. Serum amyloid P component, the major acute phase protein in mice, increased from 27 microg/ml to 339 microg/ml during the acute phase. The rate of chromatin clearance decreased during the acute phase in C57BL/10J mice. At 5 min, 18% +/- 3% of the originally measured radioactivity remained in control animals compared with 49% +/- 2% in acute phase animals (p &lt; 0.001). Co-injection of either serum amyloid P component or C-reactive protein, the major acute phase protein in humans, caused a decrease in the rate of chromatin clearance similar to that observed following the induction of the APR. APR induction also caused a higher percentage of the chromatin to localize in the liver compared with the spleen, with the ratio changing from 10.2 +/- 0.7 to 16.1 +/- 1.9 (p &lt; 0.004). In addition, the APR caused a decrease in the percentage of chromatin localized in the kidney. The lack of radioactivity associated with cells in the circulation indicates that complement is not a major factor in the clearance mechanism of chromatin. These findings suggest that the APR produces major changes in the rate and path of chromatin clearance. These changes may protect against deposition of chromatin in target organs of systemic lupus erythematosus.
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Break, Timothy, Sujung Jun, Mohanalaxmi Indramohan, Ladislav Dory, and Rance Berg. "Extracellular superoxide dismutase impairs neutrophil function and clearance of Listeria monocytogenes (118.4)." Journal of Immunology 188, no. 1_Supplement (2012): 118.4. http://dx.doi.org/10.4049/jimmunol.188.supp.118.4.
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Abstract It is well established that reactive oxygen species (ROS) play a critical role during immune responses against pathogens. Extracellular superoxide dismutase (ecSOD) regulates extracellular concentrations of ROS and protects tissues during non-infectious inflammatory insults. However, how ecSOD activity impacts immune responses directed against pathogenic microorganisms has not been thoroughly investigated. We utilized mice with varying levels of ecSOD activity to investigate the involvement of this enzyme in innate immune responses against Listeria monocytogenes. Our data demonstrate that ecSOD activity negatively impacted host survival and bacterial clearance from the spleen and liver. Paradoxically, ecSOD activity was associated with increased percentages of neutrophils in the livers of mice prior to, and during infection. Neutrophils from livers of mice with high ecSOD activity were altered in their ability to produce various molecules important for bacterial clearance. Additionally, ecSOD activity was associated with a higher percentage of neutrophils that phenotypically resembled myeloid-derived suppressor cells. Neutrophil depletion studies revealed that high ecSOD activity resulted in neutrophils with no protective capacity, whereas neutrophils from mice lacking ecSOD provided superior protection compared to neutrophils from wild-type mice. Collectively, our data demonstrate that ecSOD activity inhibits innate immune responses, thus impairing bacterial clearance.
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Claver, Adrián, Andrea Hernández Acosta, Eneko Barba, et al. "Study and Optimization of the Punching Process of Steel Using the Johnson–Cook Damage Model." Metals 14, no. 6 (2024): 616. http://dx.doi.org/10.3390/met14060616.
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Sheet metal forming processes are widely used in applications such as those in the automotive or aerospace industries. Among them, punching is of great interest due to its high productivity and low operating cost. However, it is necessary to optimize these processes and adjust their parameters, such as clearance, shear force or tool geometry, to obtain the best finishes and minimize crack generation. Thus, the main objective of this research work is to optimize the punching process to achieve parts that do not require subsequent processes, such as deburring, by controlling the properties of the starting materials and with the help of tools such as design of experiments and simulations. In the present study, tensile tests were performed on three steels with different compositions and three sample geometries. The information obtained from these tests has allowed us to determine the parameters of the Johnson–Cook damage criteria. Moreover, punching was performed on real parts and compared with simulations to analyze the percentage of burnish surface. The results obtained show that the methodology used was correct and that it can be extrapolated to other types of die-cutting processes by reducing the percentage of surface fractures and predicting the appearance of cracks. Furthermore, it was observed that clearance has a greater influence than processing speed, while the minimum percentage of the burnish area was observed for the minimum values of clearance.
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Ko, Sang-Bae, H. Alex Choi, Raimund Helbok, et al. "Quantitative analysis of hemorrhage clearance and delayed cerebral ischemia after subarachnoid hemorrhage." Journal of NeuroInterventional Surgery 8, no. 9 (2015): 923–26. http://dx.doi.org/10.1136/neurintsurg-2015-011903.
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ObjectiveInitial hemorrhage burden is an independent predictor for delayed cerebral ischemia (DCI) in patients with aneurysmal subarachnoid hemorrhage (aSAH). However, the association between clot clearance and DCI still remains to be elucidated.MethodsQuantitative analysis of hemorrhage volume and clot clearance was made in 116 consecutive patients who were scanned within 24 h from onset. Cisternal plus intraventricular hemorrhage volume (CIHV) was calculated as clot volume from the initial scans and scans performed up to 7 days after onset. Clot clearance was calculated as a percentage of residual clot volume compared with the clot volume on the initial scan. Initial clot volume and clot clearance were dichotomized to evaluate the association with DCI.ResultsIncluded patients were aged 55.5±15.2 years with a female preponderance (65.5%, (76/116)). The group with higher initial clot volume (≥17.2 mL) had higher odds for DCI (OR 4.3, 95% CI 1.3 to 14.0, p=0.015). However, the rate of DCI was not different between high and low clot clearance groups (26.7% vs 31.0%, p=0.66). Clot clearance rate was similar in patients with and without DCI up to day 7 after onset.ConclusionsThe quantitative clot clearance rate is not an independent predictor for DCI.
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Glynn‐Barnhart, Anne M., Serpil C. Erzurum, Jonathan A. Left, et al. "Pharmacokinetics of Low‐Dose Methotrexate in Adult Asthmatics." Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy 12, no. 5 (1992): 383–90. http://dx.doi.org/10.1002/j.1875-9114.1992.tb04476.x.
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Several reports have been published on the disposition of methotrexate (MTX) when given in low dosages, but none in asthmatic patients. To address this matter, pharmacokinetic studies were performed in nine patients with severe, steroid‐requiring asthma (ages 18–76 yrs) after the sixth weekly intramuscular dose of MTX. Theophylline pharmacokinetic studies were also performed at baseline prior to the start of MTX treatment and at the time of the MTX studies. Total systemic clearance of MTX, given as mean (SD), was 122.6 (25.1) ml/minute, volume of distribution at steady state 0.49 (0.2) L/kg, half‐life 3.1 (0.3) hours, mean residence time 5.0 (0.6) hours, and renal clearance 89.1 (36.3) ml/minute. These values are similar to those previously reported for other patient populations receiving low‐dose MTX. Eight of these patients were evaluated for changes in theophylline pharmacokinetics. Theophylline clearance at week 6 decreased an average of 19% from baseline and correlated inversely with total MTX clearance. Percentage change in theophylline clearance from baseline was inversely correlated with MTX nonrenal clearance, but was not statistically significant. This finding may indicate competition for clearance pathways between MTX and theophylline.
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Olsen, Niels Vidiendal, Michael Hecht Olsen, Niels Fogh-Andersen, et al. "Lithium clearance method and the renal response to low-dose dopamine in man: a randomized, controlled study." Clinical Science 84, no. 2 (1993): 237–42. http://dx.doi.org/10.1042/cs0840237.
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1. The effect of a single dose of lithium on renal function before and during intravenous infusion of dopamine (3 μg min−1 kg−1) was investigated in 12 healthy males. In a double-blind and randomized design, 450 mg or 600 mg of lithium carbonate or placebo was administered orally at 22.00 hours on three different occasions. After an overnight fast, the subjects were water-loaded and clearance studies were started at 09.00 hours with a 1 h baseline period and three 1 h periods during dopamine infusion. 2. Baseline sodium clearance with placebo was 0.65 ± 0.35 ml/min, but with lithium it increased to 1.25 ± 0.44 (P < 0.001) and 1.17 ± 0.46 ml/min (P < 0.01) after 450 and 600 mg, respectively. Urine flow rates were unchanged compared with placebo. Lithium did not significantly affect glomerular filtration rate, but both doses slightly increased effective renal plasma flow by 7% (P < 0.05) and 10% (P < 0.01), respectively. 3. The maximal natriuretic and diuretic effects of dopamine were not reduced by lithium, but the percentage increases in sodium clearance were significantly diminished after 450 mg (P < 0.01) and 600 mg (P < 0.001) of lithium. Lithium had no effect on dopamine-induced changes in effective renal plasma flow, glomerular filtration rate or osmolal clearance. Neither lithium nor dopamine influenced plasma concentrations of renin, aldosterone or atrial natriuretic peptide. 4. In conclusion, single test doses of lithium, as normally used in lithium clearance studies, increase baseline values of sodium clearance and effective renal plasma flow. Although these effects of lithium do not reduce the maximal renal responses to low-dose dopamine, they result in an underestimation of the percentage increase in sodium excretion.
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Nouws, Jacques F. M., Tom B. Vree, Margriet Baakman, Freek Driessens, Henk J. Breukink, and Dick Mevius. "Age and dosage dependency in the plasma disposition and the renal clearance of sulfamethazine and its N4-acetyl and hydroxy metabolites in calves and cows." American Journal of Veterinary Research 47, no. 3 (1986): 642–49. https://doi.org/10.2460/ajvr.1986.47.03.642.
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SUMMARY Plasma disposition, protein binding, urinary recovery, and renal clearance of sulfamethazine (smz), its N4-acetylsulfamethazine (N4-smz), and its 2 hydroxy metabolites—6-hydroxymethylsulfamethazine (sch2oh) and 5-hydroxysulfamethazine (soh)—and the glucuronide of the latter were studied in 7 cows and 7 calves to determine the relationship between these values and the age of the animal and dosage applied. A capacity-limited hydroxylation of smz into sch2oh was observed in cows and calves given dosages of 100 to 200 mg/kg. A biphasic smz elimination curve and steady state in sch2oh plasma concentration (6 to 15 μg/ml) were observed. The N4-smz plasma concentration-time curve was parallel to that of smz at the dosages and in all animals. The total body clearance and the cumulative urinary recovery (expressed as percentage of the dose) for smz and its metabolites depended on drug dosage and age of the animals. At dosages of smz < 25 mg/kg, the main metabolite in the urine of calves and cows was sch2oh (23% to 55.2%), whereas in calves given a larger dosage (100 mg/kg), the N4-smz and soh percentages increased. The plasma protein binding of smz and its metabolites depended on the smz plasma concentration. Hydroxylation lowered the protein binding (from 75-80%) to 50%. The renal clearance of smz was dependent on urine flow in all animals. The renal clearance of the sch2oh metabolite was 2 to 3 times greater than the creatinine clearance value; thus, this compound was excreted by glomerular filtration and partly by tubular secretion. Both N4-smz and soh were predominantly excreted by tubular secretion; at dosages of smz of 100 to 200 mg/kg, and N4-smz clearance was diminished. Intravenous administration of N4-smz to a calf resulted in deacetylation and a subsequent hydroxylation of the formed smz into the 2 hydroxy metabolites. It was concluded that the elimination half-life of smz in ruminants depended mainly on the extent of the metabolism, which was dose related, and on the renal clearance of its metabolites.
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Rodvold, K. A., D. A. Rushing, and D. A. Tewksbury. "Doxorubicin clearance in the obese." Journal of Clinical Oncology 6, no. 8 (1988): 1321–27. http://dx.doi.org/10.1200/jco.1988.6.8.1321.
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A study was carried out to examine the effect, if any, of obesity on doxorubicin pharmacokinetics. Body weight was found to be significantly related to doxorubicin clearance (r = -.75; P less than .001) and elimination half-life (r = .62; P = .003). Thus, the contribution of obesity on pharmacokinetics of antineoplastic agents should be taken into consideration in the analysis of clinical data with respect to toxicity and tumor response. Twenty-one patients were studied with their first course of doxorubicin (50 to 70 mg/m2) administered as a 60-minute intravenous (IV) infusion. Patients were divided into three groups on the basis of percentage of ideal body weight (IBW): normal (less than 115% IBW), mildly obese (115% to 130% IBW), and obese (greater than 130% IBW). Blood samples were collected up to 48 hours after the infusion and analyzed for doxorubicin and its metabolite, doxorubicinol, by high performance liquid chromatography. Doxorubicin area under the curve (AUC) was greater in obese than in normal patients (2,209 v 1,190 ng h/mL; P less than .05), yielding correspondingly reduced systemic clearance of the agent in obese patients (891 v 1,569 mL/min; P less than .001). The mean elimination half-life (T1/2) was 20.4 hours in the obese patients and 13.0 hours in the normal patients. The apparent volume of distribution (Vss) was not significantly different among the three groups of patients, indicating that the prolonged T1/2 in the obese patients is due to the reduction in clearance. The AUC and T1/2 of doxorubicinol were similar among all patient groups.
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Aguilar Osorio, Rita, and Keith Cliffe. "Numerical Simulation of Heat Losses between a Partition Plate and the Wall of the Head of a Plastic Heat Exchanger." Defect and Diffusion Forum 297-301 (April 2010): 650–55. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.650.
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For this research it was considered that the heat exchanger was affected by leakage in the head across the partition plate and the wall between the tube passes. Leakage was a problem in the plastic shell and tube heat exchanger, because it was difficult to seal the partition plate to the head of the exchanger. The material used for manufacturing the heat exchanger was polyvinylidene fluoride, PVDF. In order to predict the amount of flow leaking through the clearances of the tube passes, a numerical simulation was carried out using the computational Fluid Dynamics CFD Fluent Software. To obtain the percentage of the heat loss across the 4 tube passes, different clearance sizes between the partition plate and the wall of the head of the exchanger were analysed. For the smaller clearance size of 0.2 mm the heat transfer coefficient was reduced up to 15%. These results suggest that the flow mass bypassing the head between tube passes affect the results of the heat transfer coefficient and confirm the experimental observation, that its performance was affected by leakage between tube passes. This research served as an extension of the preliminary plastic heat exchanger design.
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Giménez, F., and J. Marco-Algarra. "The prognostic value of mucociliary clearance in predicting success in tympanoplasty." Journal of Laryngology & Otology 107, no. 10 (1993): 895–97. http://dx.doi.org/10.1017/s0022215100124727.
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AbstractMucociliary and equipressive eustachian tube functions have been studied, using saccharin solution (five per cent sodium saccharinate) and tubal manometry respectively, in 58 ears with chronic disease undergoing tympanoplasty. The position of the perforation site determines the results as the poorest results are obtained from the posterior ones, positive cases (47 per cent) and mean transport time (37.7 minutes), compared to the greater percentage of positive cases (86 per cent) and mean transport time (22.2 minutes) for anterior perforations.When both parameters are analysed together there is a direct relationship between normal equipressive function and normal mucociliary transport time and between negative transport time and tubal blocking. Significant differences in transport times have been found for the anterior and posterior perforations being shorter for the anterior ones.When surgical outcome is correlated with mucociliary transport, the normal transport time percentage is seen to be considerably higher in the success group (50 per cent) than in the failure group (22 per cent).
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Ruggieri, Giancarlo. "Impossibility of Comparing Data of Indexed Peritoneal Creatinine Clearance when Different Formulae of Body Surface Area are Used." Nephrology @ Point of Care 1, no. 1 (2015): poc.5000191. http://dx.doi.org/10.5301/poc.5000191.
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Background This study aimed to determine the differences arising form indexing a measured physiological variable by using different body surface area (BSA) estimation formulae. Methods The studied variables were the overall measured peritoneal creatinine clearance plus residual renal clearances (MeasCtCl) of 19 men and 23 women in a stable condition who were undergoing peritoneal dialysis and were a mean 55.7 ± 15.8 and 55.1 ± 14.1 years of age, respectively. The patients had comparable body mass indexes (BMIs; 25.01 ± 4.14 in men and 24.5 ± 3.46 in women). The MeasCtCls were indexed to 1.73 m2 using 5 formulae: by Du Bois, Boyd, Mosteller, Livingston and Yu. The numerical and percentage differences between the MeasCtCl values and each approach to indexation were calculated, as well as the differences between the indexations. Paired t-test and similarity percentage test were used to evaluate the significance of the differences. Results The impossibility of adequately comparing data indexed according to different BSA estimation formulae was shown, documenting a high risk of erroneous evaluations and conclusions. Conclusions Some methods to avoid these errors in clinical applications are suggested, as well as the possibility of indexing only to height.
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C. Nwokonko, Swinton. "Remodelling of Lee’s Knife Diffraction Loss Model as a Function of Line of Site Percentage Clearance." International Journal of Theoretical and Applied Mathematics 3, no. 4 (2017): 138. http://dx.doi.org/10.11648/j.ijtam.20170304.12.
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Hutchison, Michael G., Alex P. Di Battista, David W. Lawrence, Kyla Pyndiura, Danielle Corallo, and Doug Richards. "Randomized controlled trial of early aerobic exercise following sport-related concussion: Progressive percentage of age-predicted maximal heart rate versus usual care." PLOS ONE 17, no. 12 (2022): e0276336. http://dx.doi.org/10.1371/journal.pone.0276336.
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Objective To examine the effect of a readily accessible, structured aerobic exercise intervention on days to asymptomatic status and days to medical clearance compared to usual care exercise prescription in a cohort of adolescents and young adults following sport-related concussion (SRC). Methods A longitudinal, randomized, non-blinded clinical trial consisting of a structured aerobic exercise protocol (SAEP) group and a usual care exercise prescription (UCEP) group. Participants in the SAEP group underwent an exercise protocol including 8 sessions over 11 days progressing in duration and intensity stepwise based on participants’ age-predicted maximal heart rate. Symptom follow-ups were on days 7, 14, 21, and 28. The primary outcome measures of the study were days to asymptomatic status and days to medical clearance, while the secondary outcome measure was symptom severity on days 7, 14, 21, and 28. Results 38 participants (SAEP, n = 20; UCEP, n = 19) were recruited and completed all follow-up appointments. Compared to the UCEP group, the SAEP had a faster time to asymptomatic status with 96% posterior probability. In addition, the SAEP group displayed an earlier time to medical clearance with 93% posterior probability. While symptom severity scores did not differ between groups at enrolment (SAEP symptom severity, 30; UCEP, 29), they were subsequently lower in the SAEP group at all assessments throughout the trial with 100% posterior probability. Conclusions An aerobic exercise protocol based on percentages of age-predicted maximum heart rate is a safe and effective treatment for reducing symptoms and can be initiated during the first week following SRC. Trial registration ClinicalTrials.gov, no. NCT02969824.
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L., Manoj Kumar, Raadhika Shree N., and Anand K. H. "Effects of slough clearance rates post adult tonsillectomy in patients with laryngopharyngeal reflux disease." International Journal of Otorhinolaryngology and Head and Neck Surgery 5, no. 6 (2019): 1486. http://dx.doi.org/10.18203/issn.2454-5929.ijohns20194549.
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<p class="abstract"><strong>Background:</strong> Laryngopharyngeal reflux is known to be associated with multiple disease of the upper aero digestive tract and can cause serious injury to the mucosa long term.</p><p class="abstract"><strong>Methods:</strong> Patients diagnosed with chronic tonsillitis and indicated for surgery were evaluated for laryngopharyngeal reflux using reflux symptom index score. When score greater than 13 was suggestive of laryngopharyngeal reflux (LPR) and counselled for 24 hours ambulatory dual probe pH monitoring. When the reflux event was 7 or more were diagnosed having LPR. Patients were divided into two groups Group A patients with chronic tonsillitis and without LPR and Group B patients with chronic tonsillitis and LPR. Postoperatively there slough percentage was calculated as 25%, 50%, 75%, 100% on the postoperative day (POD) 7, 14 and 21. Slough clearance rates were calculated as 100- slough percentage. </p><p class="abstract"><strong>Results:</strong> There were 40 patients in Group A and 40 patients in Group B. The slough clearance rates of Group A were 46.3, 73.8 and 96.9 on post-operative days 7, 14, 21 respectively. The slough clearance rates of Group B were 30.1, 57.6, 90.1 on POD 7, 14, 21 respectively. The p values comparing slough clearance rates showed 0.00, 0.002, 0.013 on POD 7, 14, 21 which was statistically significant. Group B with laryngopharyngeal reflux had delayed healing than Group A.</p><p class="abstract"><strong>Conclusions:</strong> Laryngopharyngeal reflux seems to adversely affect healing and complication following tonsillectomy due to lowering of slough clearance rates. Hence we recommend the need for assessment and treatment pre/post operatively of laryngopharyngeal reflux disease in adult patients undergoing tonsillectomy.</p>
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Hansen, Tom G., Kenneth F. Ilett, Chris Reid, Soo Im Lim, L. Peter Hackett, and Riccardo Bergesio. "Caudal Ropivacaine in Infants." Anesthesiology 94, no. 4 (2001): 579–84. http://dx.doi.org/10.1097/00000542-200104000-00009.
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Background Ropivacaine is a new long-acting amino-amide local anesthetic. However, there are no data on its use in infants. In the current study, the authors investigated the pharmacokinetics of caudal ropivacaine in 30 infants younger than 12 months. Methods Two groups of infants (group 1 [n = 15], aged 0-3 months; group 2 [n = 15], aged 3-12 months) were given a caudal bolus dose of 0.2% ropivacaine (2 mg/kg) and a standardized general anesthetic technique. Serial blood samples taken for up to 12 h were analyzed for total and free ropivacaine using high-performance liquid chromatography. Population pharmacokinetic modeling was performed to yield estimates of clearance, volume of distribution, and absorption rate constant. An analysis of covariates on the kinetic parameters also was made. Results Median maximum free ropivacaine concentration was significantly higher in group 1 (99 micog/l) than in group 2 (38 microg/l) (P = 0.0002), as was the median free fraction of ropivacaine (10% vs. 5%; P = 0.01). Pharmacokinetic variables of the total population were best described by a one-compartment model with first-order absorption. Mean clearance was 0.31 l.h(-1).kg(-1) (coefficient of variation [CV], 51%), volume of distribution was 2.12 l/kg (CV, 34%), and absorption rate constant was 1.61 h(-1) (CV, 46%). Mean absorption and elimination half-lives were 0.43 and 5.1 h, respectively. Age and percentage of free ropivacaine were significant covariates for clearance. Posterior Bayesian estimates of clearance were significantly higher (38%) in older children. Conclusion Total and free plasma ropivacaine concentrations after caudal ropivacaine (0.2%, 2 mg/kg) in infants were within the range of concentrations previously reported in adults and older children. Age and percentage of free ropivacaine were significant covariates of clearance.
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Ussov, W. Yu, A. M. Peters, J. Savill, et al. "Relationship between Granulocyte Activation, Pulmonary Granulocyte Kinetics and Alveolar Permeability in Extrapulmonary Inflammatory Disease." Clinical Science 91, no. 3 (1996): 329–35. http://dx.doi.org/10.1042/cs0910329.
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1. The aim of the study was to examine the relationship between granulocyte activation, pulmonary intravascular granulocyte transit, pulmonary extravascular granulocyte migration and lung injury in patients with systemic conditions (bone marrow transplant recipients, inflammatory bowel disease and systemic vasculitis) in which abnormalities of pulmonary granulocyte traffic have previously been reported. 2. A double 111In-99mTc granulocyte labelling technique was used for quantification of granulocyte kinetics in 23 patients, of whom five were control patients. The pulmonary vascular granulocyte pool was measured from dynamic data centred on the 99mTc signal and expressed as a percentage of the total blood granulocyte pool. Granulocyte migration was quantified on 24 h images using the 111In signal. Granulocyte activation was measured as the percentage of cells showing a change in shape. The clearance rate of an inhaled aerosol of 99mTc-diethylenetriaminepenta-acetic acid (DTPA) was used as a marker of lung injury. 3. Pulmonary granulocyte pool, migration, activation and aerosol clearance, although highly variable in the patient groups, were, in general, elevated compared with the controls. 4. Granulocyte activation correlated with pulmonary granulocyte pool (Rs = 0.72, n = 22, P <0.01), while the t1/2 of DTPA clearance correlated with migration (Rs = −0.84, n = 17, P < 0.01). Fifteen patients had an expanded pulmonary granulocyte pool, of whom six with no evidence of migration, had a normal DTPA clearance, while nine, who had an abnormal migration signal, had an accelerated DTPA clearance. The pulmonary granulocyte pool in these nine was significantly higher than in the six without a migration signal. 5. Activation of granulocytes results in delayed transit through the lung vasculature. With increasing margination, granulocytes migrate into the lung interstitium and injure the lung. An increased intravascular pool does not by itself lead to lung injury.
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Kinoshita, Tomohide, Deok-Soo Son, Minoru Shimoda та Eiichi Kokue. "Impact of age-related alteration of plasma α1-acid glycoprotein concentration on erythromycin pharmacokinetics in pigs". American Journal of Veterinary Research 56, № 3 (1995): 362–65. http://dx.doi.org/10.2460/ajvr.1995.56.03.362.
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SUMMARY Erythromycin (em) pharmacokinetic variables were studied after IV administration of the drug (10 mg/kg of body weight) to 1-, 6-, and 15-day-old pigs. With advancing age, from 1 day to 15 days after birth, half-life of em became shorter (3.0 hours to 1.4 hour), whereas apparent volume of distribution, total body clearance (CLt), and intrinsic clearance became greater: 0.68 to 3.28 (L/kg), 0.15 to 1.42 (L/h/kg), and 1.81 to 3.56 (L/h/kg), respectively. The percentage of plasma protein binding of em decreased from 91 to 56%, correlating well with volume of distribution and CLt values. The altered binding percentage depended on plasma α1-acid glycoprotein (agp) concentration, but not on albumin concentration. With advancing age, plasma agp concentration was markedly decreased from approximately 6,000 μg/ml to 700 μg/ml. Despite a twofold increase in intrinsic clearance with advancing age, CLt increased ninefold, implying that the decreased protein binding contributed to the increase of CLt more preferentially than did maturational development of elimination capacity. Therefore, the altered protein binding of em attributable to the change in plasma agp concentration could be a major causal factor of the age-related pharmacokinetic variables of em in pigs.
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Terashi, Kenji, Mikio Oka, Shigehiro Ohdo, et al. "Close Association between Clearance of Recombinant Human Granulocyte Colony-Stimulating Factor (G-CSF) and G-CSF Receptor on Neutrophils in Cancer Patients." Antimicrobial Agents and Chemotherapy 43, no. 1 (1999): 21–24. http://dx.doi.org/10.1128/aac.43.1.21.
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ABSTRACT Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is used to counter chemotherapy-induced neutropenia. Our previous study showed an inverse correlation between serum rhG-CSF levels and the number of circulating neutrophils in cancer patients (H. Takatani, H. Soda, M. Fukuda, M. Watanabe, A. Kinoshita, T. Nakamura, and M. Oka, Antimicrob. Agents Chemother. 40:988–991, 1996). The aim of this study was to clarify the relationship between rhG-CSF clearance and G-CSF receptors on circulating neutrophils. In five cancer patients receiving chemotherapy, a bolus dose of rhG-CSF (5 μg/kg) was injected intravenously during defined phases of posttreatment neutropenia and neutrophilia. Serum rhG-CSF levels were measured by a chemiluminescence enzyme immunoassay and analyzed by moment analysis. G-CSF receptors on neutrophils were detected by flow cytometry with biotinylated rhG-CSF. rhG-CSF clearance was significantly higher at neutrophilia than at neutropenia (1,497 ± 132 versus 995 ± 266 ml/h; P < 0.01). The percentage of G-CSF receptor-positive neutrophils, reflecting the number of G-CSF receptors per cell, was low at neutropenia without rhG-CSF therapy (44.5% ± 22.1%) and high at neutrophilia with rhG-CSF therapy (73.0% ± 11.4%; P < 0.01). rhG-CSF clearance closely correlated with the percentage of G-CSF receptor-positive neutrophils (r 2 = 0.91; P < 0.0001) and neutrophil count (r 2 = 0.72; P < 0.005). Our results indicate that, in cancer patients receiving chemotherapy, rhG-CSF increases the number of G-CSF receptors per cell as well as circulating neutrophil counts, resulting in modulation of its own clearance.
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Bai, Yun, Demian Obregon, Huayan Hou та ін. "Active Aβ vaccination-induced Aβ clearance enhanced by suppression of the CD40-CD40L interaction (48.11)". Journal of Immunology 178, № 1_Supplement (2007): S76. http://dx.doi.org/10.4049/jimmunol.178.supp.48.11.
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Abstract Active and passive Aβ immunization efficiently reduces amyloid plaque load and memory impairment in transgenic mouse models of Alzheimer’s disease. Immunization has also yielded favorable results for many patients; but a significant percentage also developed severe meningioencephalitis. Prior studies by our group suggest CD40 receptor-CD40 ligand interaction between T-cells and microglia initiates release of proinflammatory factors, which drive phenotypic switching from a phagocytic to an antigen presenting cell phenotype thus impairing the clearance of Aβ. We therefore tested whether a CD40 blockade could enhance Aβ vaccination-mediated Aβ clearance in vivo. Importantly in our present study, Aβ vaccinated CD40 deficient heterozygous transgenic mice over-expressing mutant amyloid precursor protein and presenilin-1 demonstrated enhanced Aβ clearance; compared with vaccinated PSAPP mice. Similar results were obtained with Aβ vaccinated PSAPP mice passively immunized with CD40L antibody injections. Taken together with our previous studies these data suggest that CD40 blockade, in the context of active Aβ vaccination, acts to enhance CNS Aβ clearance by maintaining microglia in a phagocytic phenotype. These data also may provide the basis for a method whereby enhancing Aβ vaccination-mediated Aβ clearance strategies.
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Friedrich, Lawrence V., Roger L. White, Dianne M. Brundage, Michael B. Kays, and Richard J. Friedman. "The Effect of Tourniquet Inflation on Cefazolin Tissue Penetration During Total Knee Arthroplasty." Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy 10, no. 6 (1990): 373–77. http://dx.doi.org/10.1002/j.1875-9114.1990.tb03565.x.
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Patients undergoing total knee arthroplasty were randomized to tourniquet inflation 1, 2, or 5 minutes after a 1‐g dose of cefazolin. Serum, soft tissue, and bone samples were obtained at 10, 30, and 60 minutes after inflation, immediately prior to tourniquet release (PTR), and 5 minutes after release. Areas under the concentration‐time curve (AUC10‐PTR) were calculated using the linear trapezoidal method and normalized to actual body weight, creatinine clearance, and length of tourniquet inflation. The percentage of penetration was calculated using the normalized values for the respective AUCs. Differences among the groups were analyzed using analysis of variance or the Kruskal‐Wallis test where appropriate. Groups were similar for age, actual body weight, duration of tourniquet inflation, and creatinine clearance (p > 0.05). The median percentages of penetration for soft tissue and bone at 5, 2, and 1 minute were 14.5% and 4.6%, 6.7% and 3.0%, and 5.9% and 4.6%, respectively. Only the percentage of soft tissue penetration between 5 and 1 minute was significantly different (p = 0.015). Gender and type of anesthesia (general, epidural) had no effect on cefazolin penetration into soft tissue or bone. Although increasing the time interval between cefazolin administration and tourniquet inflation resulted in higher soft tissue drug concentrations, a 1 ‐ minute interval resulted in soft tissue and bone cefazolin concentrations at or above the minimum inhibitory concentration for microorganisms likely to be encountered in this surgical procedure.
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Schifferli, J. A., Y. C. Ng, J. Estreicher, and M. J. Walport. "The clearance of tetanus toxoid/anti-tetanus toxoid immune complexes from the circulation of humans. Complement- and erythrocyte complement receptor 1-dependent mechanisms." Journal of Immunology 140, no. 3 (1988): 899–904. http://dx.doi.org/10.4049/jimmunol.140.3.899.
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Abstract The role of complement and its receptor on erythrocytes (CR1) in the physiologic elimination of large immune complexes from the circulation of humans was assessed. Large radiolabeled soluble tetanus toxoid- anti-tetanus toxoid complexes were injected i.v. into three normal individuals and three patients with SLE. These complexes were prepared in antibody excess and were 45S in size, fixed C and bound to E CR1 in vitro. The percentage of complexes bound in vitro was directly proportional to CR1 number/E in four normal subjects and three SLE patients. After i.v. injection into normal subjects, complexes were cleared rapidly, with a monoexponential rate constant (10.3 to 11% complexes cleared/min). In the SLE patients, clearance was best explained by two phases: the first occurred within the first minute indicating immediate trapping of a fraction of the complexes (19.5 to 25.3% of injected complexes trapped), the second was monoexponential and was similar to the normal range. A large fraction of complexes bound within the first minute to E in vivo; the percentage of binding was variable, ranging from 16.3% to 71.5% and was related to E CR1 number. In a second study complexes were injected that had been attached to autologous E by opsonization with C in vitro. Their elimination was similarly monoexponential, except in one SLE patient in whom there was significant initial trapping (30.9%). A fraction of these complexes were released from E within the first minute, the percentage release being greatest in the patient with the lowest CR1 number (81.4%). E bearing immune complexes remained in the circulation and were not transiently sequestered in the liver or spleen. This is the first study of the clearance of soluble immune complexes in vivo in humans and shows that C and CR1 on E participate in immune complex clearance reactions, and that abnormal clearance can be detected in the form of rapid removal of immune complexes from the circulation.
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Adkison, Michael, Andrew Armenta, Frank Winsett, and Richard Wagner. "Review of Tumor Margins for Lentigo Maligna with Staged Surgical Excision and Permanent Section en face Processing." SKIN The Journal of Cutaneous Medicine 8, no. 4 (2024): 1672–80. http://dx.doi.org/10.25251/skin.8.4.5.
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Background: The optimal surgical margins required for the excision of lentigo maligna remains a topic of debate. Recent literature suggests that wider margins are warranted. Objective: Comparison of lentigo maligna margin sizes and clearance rates from a single center to existing literature. Methods: A retrospective analysis of primary and recurrent lentigo maligna treated by staged excision with complete circumferential and deep margin assessment between 2011 and 2023 at a single institution was conducted. The percentage of tumors with clear margins after the initial excision with 5 mm margins was determined. Results: A total of 65 tumors were identified. Fifty-eight patients (89.2%) had clear margins after initial excision with 5 mm margins. Conclusions: This study reports a higher percentage of lentigo maligna clearance following the initial staged excision with 5 mm margins than reports in the literature. These differences may be attributed to variations in section processing, staining techniques, and factors associated with differences in subclinical spread.
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Liu, Houlin, Jian Ding, Hanwei Dai, and Minggao Tan. "Investigation into Transient Flow in a Centrifugal Pump with Wear Ring Clearance Variation." Advances in Mechanical Engineering 6 (January 1, 2014): 693097. http://dx.doi.org/10.1155/2014/693097.
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The leakage flow paths in the sidewall gaps of centrifugal pumps are of significant importance for numbers of effects. The paper is concerned with the transient flow in the leakage flow paths with wear ring clearance variation. For this purpose, numerical simulations of the whole pump were carried out. The grid dependence and yplus check were performed first. Additionally, experimental data of performance characteristic and pressure fluctuation inside the sidewall gap was used to validate the numerical results. The transient velocity fields inside the sidewall gaps during one blade passage period were simulated. And the leakage through the wear ring gap was obtained for all operating points investigated. To have a better idea of attenuation and propagation of pressure inside the sidewall gap, the unsteady pressure distributions in the gap were calculated. Additionally, the surfaces of the impeller were divided into four parts. The fluid force on each part was expressed as a percentage of the total radial force. Through comparing the flow fields, the pressure distributions, and the radial force between the pumps with different wear ring clearances, the effects of the wear ring clearance were discussed in detail. The results can be used to guide the optimum design of the pump sidewall gaps.
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Subramanian, Sivakumar, AS Sekhar, and BVSSS Prasad. "On the choice of initial clearance and prediction of leakage flow rate for a rotating gas turbine seal." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 10 (2015): 1586–601. http://dx.doi.org/10.1177/0954406215581692.
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The present work proposes a design procedure along with guidelines for the choice of initial clearance of a typical rotating gas turbine seal in a secondary air system. The basis for the design is to prevent seal rubbing against stator, by ensuring that the centrifugal and thermal growths of the seal are within the safe operating limits. As a case study, a six-tooth straight-through rotating labyrinth seal configuration is considered with wide ranging seal parameters, namely the seal inner radius (25–700 mm), speed (1000–5000 rad/s), temperature (200–650 ℃) and pressure ratio (1.1–2.5). By means of an iterative process, which involves computational fluid dynamics and finite element analysis techniques, and with a choice of initial clearance, an extensive database is generated. The results are presented in terms of non-dimensional variables, namely seal clearance ratio, centrifugal growth ratio, thermal growth ratio, operating clearance ratio due to centrifugal growth and operating clearance ratio due to thermal growth. It is found that the value of clearance ratio depends significantly on the dimensionless radial position. For a seal clearance ratio of 0.01, at 3000 rad/s, the leakage flow rate gets reduced by 18 and 4%, respectively for pressure ratios of 1.1 and 2.5, when the centrifugal growth alone is considered. When both centrifugal and thermal growths are considered, the percentage reduction becomes about 70% for the same seal operating at 3000 rad/s and 204 ℃, and it is as high as 95% at 426 ℃.
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Tian, Quan Li, Xin Feng, Zhiming Wang, Zhengzhong Zhang, and Yongsen Xiong. "Design and Performance Assessment of Dual-Speed Axial Threshing and Separation for Paddy Rice Combines." Applied Engineering in Agriculture 37, no. 6 (2021): 1015–22. http://dx.doi.org/10.13031/aea.13887.
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HighlightsDual-speed axial threshing and separation was designed to improve performance.Loosely connected grains were removed firstly for reducing opportunity for breakage.Machine is complex but a lower effective cylinder speed can reach a good performance.Reasonable feed rate and concave clearance could maintain quality and throughput.ABSTRACT. This research was conducted to assess the performance of a combine, model number 4LZ-4.0 under different threshing functional parameters such as speed of high/low speed cylinder, cylinder-concave clearance and linear speed of concave sieve. An indoor experiment was conducted using the dual-speed axial threshing and separation. These functional parameters were set at five levels. The responses were obtained in terms of broken rate, impurity rate and loss rate. Multi-objective variable optimization was performed using Design-Expert 6.0.10 software. Analysis of variance was done to determine the significant effects of the factor variations on the response values. Design-Expert 6.0.10 software was used to present response surface graphs that were used to describe the variations of the responses as the factors changed from one level to the other. Results showed that with an increase in speed of high/low speed cylinder from 15.42/18.50-22.92/27.50m/s, the percentage of broken rate increased significantly from 0.15% to 1.13%, respectively. At cylinder speeds of 15.42/18.50m/s and 22.92/27.50 m/s rpm, the impurity rate increased from 0.31% to 1.62%, respectively. It was also realized that varying the speed of high/low speed cylinder had a significant effect on the broken rate and impurity rate. The impurity rate increased with an increase in Linear speed of concave sieve from 0.40 to 1.60 m/s, the percentage of impurity rate increased significantly from 0.31% to 1.62% respectively. However, the lowest impurity rate was obtained at an average linear speed of concave sieve of 0.99 m/s. Furthermore, it was realized that increasing the cylinder-concave clearance from 16 to 30 mm, equally increased the percentage of loss rate from 1.78% to 2.93%. From the results obtained, it was suggested that operating the threshing cylinder at a speed of high/low speed cylinder of 18.31/21.97 m/s, cylinder-concave clearance of 22.60 mm and linear velocity of rotary concave of 0.99 m/s, gave a better performance of the machine. Keywords: Axial threshing and separation, Cylinder-concave clearance, Dual-speed, Functional parameters, Linear speed of concave sieve, Speed of high/low speed cylinder.
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Krawiec, Donald R., A. Robert Twardock, Robert R. Badertscher, Gregory B. Daniel, and Steven J. Dugan. "Use of 99mTc diethylenetriaminepentaacetic acid for assessment of renal function in dogs with suspected renal disease." Journal of the American Veterinary Medical Association 192, no. 8 (1988): 1077–80. https://doi.org/10.2460/javma.1988.192.08.1077.
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Summary The effectiveness of technetium 99m-labeled diethylenetriaminepentaacetic acid (99mTc dtpa) to assess renal function in 13 dogs with suspected renal disease was evaluated. Glomerular filtration rates (actual gfr) were determined on the basis of endogenous creatinine clearance. Predicted gfr were determined by using 99mTc dtpa within 72 hours after the determination of creatinine clearance. The percentage of an iv administered dose of 99mTc dtpa in the kidneys (percentage dose) was determined. Two equations were used to calculate predicted gfr, which were derived from previously reported linear regression analysis of inulin (In) and creatinine (Cr) gfr vs percentage dose 99mTc dtpa in dog kidneys. The correlations of actual gfr vs predicted gfr (In) and actual gfr vs predicted gfr (Cr) were both r = 0.92. The dogs’ mean actual gfr was 1.73 ± 1.35 ml/min/kg. Their mean predicted gfr (In) and predicted gfr (Cr) were 1.92 ± 1.42 ml/min/kg and 1.85 ± 1.27 ml/min/kg, respectively. Therefore, 99mTc dtpa can be used with high accuracy as an agent to predict gfr in dogs with suspected renal disease. The procedure for determining gfr by use of nuclear medicine was rapid and noninvasive and appeared to induce little stress in the animals evaluated.
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Koblik, Philip D., William J. Homof, Chi-Kwan Yen, Paul E. Fisher, and Jan Komtebedde. "Use of technetium-99m sulfur colloid to evaluate changes in reticuloendothelial function in dogs with experimentally induced chronic biliary cirrhosis and portosystemic shunting." American Journal of Veterinary Research 56, no. 5 (1995): 688–93. http://dx.doi.org/10.2460/ajvr.1995.56.05.688.
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SUMMARY Technetium-99m sulfur colloid scintigraphy was used to study alterations of reticuloendothelial function in 7 dogs with experimentally induced biliary cirrhosis and portosystemic shunting. Scintigraphic studies were performed before and 6 weeks after common bile duct ligation. Radiocolloid plasma clearance rate was determined by measuring activity in plasma samples and by analyzing the rate of liver uptake on dynamic scintigraphic image sequences. Percentage of uptake in the liver, spleen, and lungs, as well as the ratio of hepatic-to-extrahepatic uptake, was determined from static equilibrium images. Relative to preoperative values, there were significant decreases in plasma clearance rate, percentage of fiver uptake, and ratio of hepatic-to-extrahepatic uptake and significant increases in percentage of spleen and lung uptake on postoperative studies. The mechanism of technetium-99m-labeled sulfur colloid extraction by the liver is different from that of other radiocolloids; it does not require active phagocytosis or pinocytosis. Thus, fiver uptake of this tracer principally reflects effective liver blood flow. Portosystemic shunting was documented in these dogs at the time of the postoperative radiocolloid scans, and we believed was responsible for the decrease in liver reticuloendothelial activity. Possible mechanisms for the increased splenic and pulmonary reticuloendothelial activities are discussed.
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Lai, K. H., N. J. Peng, G. H. Lo, et al. "Prediction of recurrent choledocholithiasis by quantitative cholescintigraphy in patients after endoscopic sphincterotomy." Gut 41, no. 3 (1997): 399–403. http://dx.doi.org/10.1136/gut.41.3.399.
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Background—Endoscopic sphincterotomy (EST) is widely used for the removal of stones from the bile duct, but stones recur in about one fifth of patients.Aims—To investigate hepatic clearance by quantitative cholescintigraphy (QC) in patients after EST and to discern the relationship between biliary emptying and stone recurrence.Methods—One hundred and forty nine patients who had EST and clearance of the bile duct for choledocholithiasis were selected. All patients were confirmed to have complete EST by sphincter of Oddi manometry and underwent QC soon after normalisation of liver function. Regular clinical follow up was performed for each patient.Results—During a mean 36 month follow up, 22 (14.8%) patients developed recurrent stones in the bile duct. Irrespective of the status of the gall bladder, patients with recurrent stones had a slower hepatic clearance of radioisotope during QC compared with patients without stone recurrence, but only the differences in cholecystectomised patients had statistical significance. After carrying out multivariate analysis, one parameter of QC, percentage clearance of maximal count at 45 minutes, was found to be the only significant factor for stone recurrence. All recurrent stones in the common bile duct were successfully removed at endoscopy.Conclusion—Slower hepatic clearance as shown by QC is an important factor responsible for stone recurrence after sphincter ablation.
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Reichert, Megan M., Emily M. Rheaume, Jesse M. Skoch, et al. "Improving Cervical Spine Clearance Documentation in the Pediatric Trauma Patient: A Quality Improvement Project." Journal of Trauma Nursing 32, no. 2 (2025): 108–13. https://doi.org/10.1097/jtn.0000000000000840.
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BACKGROUND: Cervical spine clearance of pediatric trauma patients requires consistent, clear documentation for multidisciplinary trauma team members to provide safe care. Yet, cervical spine clearance often remains inconsistently and inappropriately documented. OBJECTIVE: This study evaluated the effects of a cervical spine clearance documentation initiative on documentation adherence rates. METHODS: This quality improvement study used a Plan-Do-Study-Act with iterative cycles and prospective data collection conducted from May 2022 to September 2023 in a large urban freestanding, Midwestern, U.S. Level I pediatric trauma center. The inclusion criteria were pediatric trauma patients aged 0–18 years with Glasgow Coma Scale scores ≥14 at clearance who required cervical collar placement. The multicomponent intervention comprised a standardized electronic note, enhanced multidisciplinary education, updated clinical guidelines, and weekly chart reviews with Pareto analysis. Outcome measures were adherence rates with a goal set at greater than 80% compliance. RESULTS: A total of 550 patients were included in the study time period. The cervical spine documentation rate improved from a baseline pre-implementation rate of 10% to a post-implementation rate of 85% and has been sustained for the past 13.5 months. CONCLUSIONS: Implementing a standardized cervical spine clearance note increased the percentage of appropriate documentation, reducing the uncertainty regarding safe collar removal.
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Bhatt-Mehta, Varsha, and Gail Annich. "Sedative clearance during extracorporeal membrane oxygenation." Perfusion 20, no. 6 (2005): 309–15. http://dx.doi.org/10.1191/0267659105pf827oa.
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The effects of polyvinyl chloride (PVC) tubing and membrane oxygenator (MO) on the concentrations of lorazepam and morphine in the neonatal extracorporeal membrane oxygenation (ECMO) circuit were evaluated using an in vitro model that included a closed ECMO circuit with a MO, heat exchanger, bladder and PVC tubing. The circuit was primed with blood, electrolytes, albumin and heparin and maintained at physiologic pH and temperature throughout by frequent measurement of blood gas pH and a temperature probe. Lorazepam and morphine were each studied separately in three separate, but identical circuits for 6 h on the day of circuit prime (new circuit) and then again for 6 h at 24 h (old circuit). Each circuit (new and old) was spiked once with lorazepam to a final concentration of 250 ng/mL or with morphine to a final concentration of 70 ng/mL in the circuit. Serial samples were drawn at baseline and every 30/60 min for 6 h at the site of injection and pre- and post-MO for each circuit. Lorazepam and morphine concentrations were analysed using gas chromatography with electron capture and gas chromatography with mass spectrometry, respectively. The concentrations of morphine and lorazepam at various sample sites and time points were expressed as a percentage of the original concentration. This single-dose study shows that up to 50% of a dose of lorazepam and 40% of a dose of morphine may be extracted by PVC and MO during bypass, depending on the age of the circuit. As the circuits become older, this amount could increase. These data may explain, in part, the higher doses of lorazepam and morphine required to sedate patients during ECMO.
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Everhart, Alexander O., Soumya Sen, Ariel D. Stern, Yi Zhu, and Pinar Karaca-Mandic. "Association Between Regulatory Submission Characteristics and Recalls of Medical Devices Receiving 510(k) Clearance." JAMA 329, no. 2 (2023): 144. http://dx.doi.org/10.1001/jama.2022.22974.
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ImportanceMost regulated medical devices enter the US market via the 510(k) regulatory submission pathway, wherein manufacturers demonstrate that applicant devices are “substantially equivalent” to 1 or more “predicate” devices (legally marketed medical devices with similar intended use). Most recalled medical devices are 510(k) devices.ObjectiveTo examine the association between characteristics of predicate medical devices and recall probability for 510(k) devices.Design, Setting, and ParticipantsIn this exploratory cross-sectional analysis of medical devices cleared by the US Food and Drug Administration (FDA) between 2003 and 2018 via the 510(k) regulatory submission pathway, linear probability models were used to examine associations between a 510(k) device’s recall status and characteristics of its predicate medical devices. Public documents for the 510(k) medical devices were collected using FDA databases. A text extraction algorithm was applied to identify predicate medical devices cited in 510(k) regulatory submissions. Algorithm-derived metadata were combined with 2003-2020 FDA recall data.ExposuresCitation of predicate medical devices with certain characteristics in 510(k) regulatory submissions, including the total number of predicate medical devices cited by the applicant device, the age of the predicate medical devices, the lack of similarity of the predicate medical devices to the applicant device, and the recall status of the predicate medical devices.Main Outcomes and MeasuresClass I or class II recall of a 510(k) medical device between its FDA regulatory clearance date and December 31, 2020.ResultsThe sample included 35 176 medical devices, of which 4007 (11.4%) were recalled. The applicant devices cited a mean of 2.6 predicate medical devices, with mean ages of 3.6 years and 7.4 years for the newest and oldest, respectively, predicate medical devices. Of the applicant devices, 93.9% cited predicate medical devices with no ongoing recalls, 4.3% cited predicate medical devices with 1 ongoing class I or class II recall, 1.0% cited predicate medical devices with 2 ongoing recalls, and 0.8% cited predicate medical devices with 3 or more ongoing recalls. Applicant devices citing predicate medical devices with 3 or more ongoing recalls were significantly associated with a 9.31–percentage-point increase (95% CI, 2.84-15.77 percentage points) in recall probability compared with devices without ongoing recalls of predicate medical devices, or an 81.2% increase in recall probability relative to the mean recall probability. A 1-SD increase in the total number of predicate medical devices cited by the applicant device was significantly associated with a 1.25–percentage-point increase (95% CI, 0.62-1.87 percentage points) in recall probability, or an 11.0% increase in recall probability relative to the mean recall probability. A 1-SD increase in the newest age of a predicate medical device was significantly associated with a 0.78–percentage-point decrease (95% CI, 1.29-0.30 percentage points) in recall probability, or a 6.8% decrease in recall probability relative to the mean recall probability.Conclusions and RelevanceThis exploratory cross-sectional study of 510(k) medical devices cleared by the FDA between 2003 and 2018 demonstrated significant associations between 510(k) submission characteristics and recalls of medical devices. Further research is needed to understand the implications of these associations.
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Reilly, Christopher, Chris Amidei, Jocelyn Tolentino, Babak S. Jahromi, and R. Loch Macdonald. "Clot volume and clearance rate as independent predictors of vasospasm after aneurysmal subarachnoid hemorrhage." Journal of Neurosurgery 101, no. 2 (2004): 255–61. http://dx.doi.org/10.3171/jns.2004.101.2.0255.
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Object. This study was conducted for two purposes. The first was to determine whether a combination of measurements of subarachnoid clot volume, clearance rate, and density could improve prediction of which patients experience vasospasm. The second was to determine if each of these three measures could be used independently to predict vasospasm. Methods. Digital files of the cranial computerized tomography (CT) scans obtained in 75 consecutive patients admitted within 24 hours of subarachnoid hemorrhage (SAH) were analyzed in a blinded fashion by an observer who used quantitative imaging software to measure the volume of SAH and its density. Clot clearance rates were measured by quantifying SAH volume on subsequent CT scans. Vasospasm was defined as new onset of a focal neurological deficit or altered consciousness 5 to 12 days after SAH in the absence of other causes of deterioration, diagnosed with the aid of or exclusively by confirmatory transcranial Doppler ultrasonography and/or cerebral angiography. Univariate analysis showed that vasospasm was significantly associated with the SAH grade as classified on the Fisher scale, the initial clot volume, initial clot density, and percentage of clot cleared per day (p < 0.05). In multivariate analysis, initial clot volume and percentage of clot cleared per day were significant predictors of vasospasm (p < 0.05), whereas Fisher grade and initial clot density were not. Conclusions. Quantitative analysis of subarachnoid clot shows that vasospasm is best predicted by initial subarachnoid clot volume and the percentage of clot cleared per day.