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At least 343 records · Page 19Linked to original sources
PubMed2003

An orally active adenosine A1 receptor antagonist, FK838, increases renal excretion and maintains glomerular filtration rate in furosemide-resistant rats.

1. Loop and thiazide diuretics are common therapeutic agents for the treatment of sodium retention and oedema. However, resistance to diuretics and decreases in renal function can develop during diuretic therapy. Adenosine causes renal vasoconstriction, sodium reabsorption, and participates in the tubuloglomerular feedback mechanism for the regulation of glomerular filtration rate. 2. We tested the hypothesis that the selective adenosine A(1) receptor antagonist FK838 is orally active and causes diuresis and natriuresis, but maintains glomerular filtration rate in normal rats or in rats with furosemide resistance. 3. In normal male Sprague - Dawley rats, FK838 dose-dependently increased urine flow and sodium and chloride excretion while sparing potassium. In combination with furosemide, FK838 enhanced the diuretic and natriuretic actions of furosemide to the same extent as hydrochlorothiazide and did not increase the potassium loss in normal rats. In furosemide-resistant rats, FK838 increased urine flow and electrolyte excretion to a greater extent than hydrochlorothiazide. In addition, hydrochlorothiazide significantly decreased glomerular filtration rate, whereas FK838 maintained glomerular filtration rate in furosemide-resistant rats. 4. This study shows that the adenosine A(1) receptor antagonist FK838 is orally active and causes potent diuresis and natriuresis and maintains glomerular filtration rate in normal or furosemide-resistant rats. Adenosine A(1) receptor antagonists may be novel therapeutics for the treatment of oedema in normal or otherwise diuretic-resistant patients.

Adenosine A1 Receptor Antagonists↗
PubMed1965

THE FRACTIONATION OF MYROTHECIUM VERRUCARIA CELLULASE BY GEL FILTRATION.

1. Culture filtrates from Myrothecium verrucaria have been fractionated by gel filtration on Sephadex G-75 to give three major cellulolytic components with molecular weights of about 55000, 30000 and 5300. 2. The middle component has the bulk (90%) of the total carboxymethylcellulase activity and is little affected by exposure to cotton. The other two, which are mainly responsible for the activity of the filtrate towards cotton, are removed or deactivated by exposure to it. These observations accord with the previously reported behaviour of the whole culture filtrate. There is no evidence for interconversion of, or synergism between, these components. 3. Temperature control during gel filtration is necessary for reproducible results at high resolution. The effect of a change in temperature has been explained in terms of changes in the degree of swelling of the gel particles.

Biochemical Phenomena↗
PubMed1981

Blood-volume expansion in the rat: natriuresis accompanied by a fall in filtration fraction.

1. We have attempted to confirm the existence of a natriuretic hormone released in response to acute expansion of blood volume. 2. Isolated kidneys, perfused with whole blood at constant pressure, were incorporated within an extracorporeal circulation in recipient rats. In six control experiments urine flow rate, renal blood flow, glomerular filtration rate, filtration fraction, and the fractional excretion of filtered sodium and water were measured for periods of up to 120-140 min thereafter. The same variables were measured in a further 12 experiments in which, after 63 +/- 11 min, the rats were volume expanded with equilibrated whole blood (15, 18 or 28 ml/kg body wt). 3. On average the controls revealed no change in any of the variables measured; volume expansion was followed by increased renal blood flow and fractional excretion of filtered sodium and water, while the filtration fraction fell. 4. In both the control and volume-expansion experiments, there were 12 instances in which the fractional excretion of filtered sodium increased; in 10 of these, including those experiments in which the natriuresis was most marked, there was a closely correlated fall in filtration fraction. 5. In all the experiments changes in the fractional excretion of filtered sodium and water varied in parallel. 6. We conclude that volume expansion (a) changes the concentration of some circulating vasoactive substance(s) and (b) results in natriuresis and diuresis consequent upon a fall in filtration fraction.

Animals↗
PubMed2001

Enrichment of high-quality spermatozoa in bovine semen: relative effectiveness of three filtration matrixes.

To be practical, any method for improving bull semen must yield a large quantity of motile spermatozoa. Some separation methods based on physical properties, e.g. filtration, chromatography, centrifugation, washing and pooling, have been reported as satisfactory, but generally are not repeatable. Nevertheless, filtration methods appear to allow the attainment of an acceptable number of spermatozoa, thus allowing such a technique to be introduced in the production of standard bovine semen doses for artificial insemination. The aim of this work was to evaluate systematically the relative effects of three filtration matrixes (silica oxide, glass beads or Sephadexätrade mark) on the improvement of whole ejaculate quality. Analysis of the type of matrix and the volume and height of the filtration column was performed. The only characteristic of the columns that appears to influence ejaculate quality after filtering is the matrix volume. While all matrixes produced improvement of semen quality, SephadexTM was better than the other matrixes tested. An explanation for the mechanism of column filtration is proposed.

Acrosome↗
PubMed2002

Reduction of Yersinia enterocolitica load in deliberately inoculated blood: the effects of blood prestorage temperature and WBC filtration.

BACKGROUND: Yersinia enterocolitica is known to cause severe infections in patients who receive transfusions. STUDY DESIGN AND METHODS: The aim of the study was to define the best strategy for reducing the bacterial load in blood that was deliberately contaminated with Y. enterocolitica by combining prestorage temperature and WBC filtration with conditions of blood processing close to those applied in blood banks. RESULTS: The effects of three prestorage temperatures (4 degrees C, 20 degrees C, 37 degrees C) were evaluated at various times after infection. The best reduction of bacterial load was achieved after 3 hours at 20 degrees C. In further experiments, conducted according to the former specifications, filtration of whole blood from eight and six donors with an inoculum of 100 and 500 to 1000 CFUs per mL, respectively, resulted in a total inhibition of bacterial growth up to 42 days after infection. After fractionation of blood components, in contrast to plasma and RBCs, filtration was shown to reduce dramatically the bacterial growth in buffy coats, demonstrating that the antibacterial effect of filtration was supported by the removal of infected WBCs from blood samples. CONCLUSION: These results provide support for the systematic use of blood filtration in the preparation of blood components to prevent Y. enterocolitica infection of patients receiving transfusions.

Blood Bactericidal Activity↗
PubMed1994

Inadequate white cell reduction by bedside filtration of red cell concentrates.

BACKGROUND: White cell filtration of red cell concentrates is often performed at the bedside, in the ward, with the filter inserted in the blood administration line. The aim of this study was to evaluate the efficiency of this filtration method and compare it to filtration in the blood bank. STUDY DESIGN AND METHODS: One-day-old, buffy coat-reduced, hard-packed red cell concentrates in saline-adenine-glucose-mannitol solution were filtered through different filters designed for bedside or laboratory use. With filters designed for bedside use, filtration of red cells was performed under laboratory conditions at fast flow (10 min) or under bedside conditions at slow flow (2 hours). The remaining white cells were counted microscopically. Filters designed for laboratory use were evaluated at fast flow, and the number of contaminating white cells was counted by flow cytometry. RESULTS: With bedside filters, a significantly higher contamination of white cells was found in the units filtered at slow flow than at fast flow, regardless of the filter used. The number of units with > 5 x 10(6) white cells was 52 (78%) of 67 filtered at slow flow compared to 11 (23%) of 47 at fast flow, all filters taken together. This difference in white cell contamination was mainly due to an increase of polymorphonuclear cells in the red cell concentrates filtered at slow flow. With filters designed for laboratory use, 0 to 2 percent of units (n = 1448) were contaminated with > 5 x 10(6) white cells. CONCLUSION: Bedside filtration for white cell reduction at slow flow is inefficient for 1-day-old, buffy coat-reduced red cell concentrates.

Cell Separation↗
PubMed1995

Effect of filtration of platelet concentrates on the accumulation of cytokines and platelet release factors during storage.

BACKGROUND: Platelet transfusions are frequently accompanied by febrile nonhemolytic transfusion reactions. These may be due, in part, to the release of cytokines interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor alpha (TNF-alpha) by white cells (WBCs) into the plasma during storage of platelet concentrates (PCs). Acting as endogenous pyrogens, these agents may induce inflammatory responses. STUDY DESIGN AND METHODS: This study proposed to determine if WBC reduction in PCs by filtration significantly reduced the levels of cytokines normally generated during storage of unfiltered PCs up to 5 days. Serotonin, platelet-derived growth factor (PDGF-AB), and von Willebrand factor levels were also assessed to establish whether or not filtration or storage elicited significant platelet activation and granule release. RESULTS: Filtration significantly reduced total WBC counts by 99.1 percent before storage (p < 0.001) without affecting total platelet counts. Compared to unfiltered PCs, filtration prevented a rise in the levels of each cytokine by Day 3 for IL-1 beta (27.7 vs. 0.6 pg/mL; p < 0.05), IL-6 (114.2 vs. 0.4 pg/mL; p < 0.001), and IL-8 (4.2 vs. 0.02 ng/mL; p < 0.001). By Day 5, further increases in the levels of all cytokines were noted in unfiltered PCs, but Day 0 levels remained in filtered PCs (IL-1 beta: 105.4 vs. 0.4 pg/mL, p < 0.001; TNF-alpha: 42.2 vs. 7.5 pg/mL, p < 0.025; IL-6: 268.8 vs. 0.4 pg/mL, p < 0.001; and IL-8: 7.6 vs. 0.02 ng/mL, p < 0.001). From Day 0 to Day 5, there were significant increases in serotonin (21.3 vs. 6.3 ng/mL, p < 0.05), PDGF-AB (72.6 vs. 25.8 ng/mL, p < 0.001), and von Willebrand factor (4.7 vs. 2.7 IU/mL, p < 0.05) in unfiltered PCs, with similar increased levels being observed in filtered PCs during storage. CONCLUSION: These data indicate that the accumulation of high levels of cytokines in stored PCs could be prevented by WBC-reduction filtration of PCs without the induction of significant platelet activation or granule release. As cytokines have the potential to induce febrile nonhemolytic transfusion reactions in patients, the transfusion of WBC-reduced PCs would be expected to reduce the frequency and severity of such reactions.

Blood Platelets↗
PubMed2002

WBC filtration of whole blood after prolonged storage at ambient temperature by use of an in-line filter collection system.

BACKGROUND: Before-storage WBC reduction by filtration appears to be an effective way to prevent transfusion-associated complications. It also has superiority over WBC reduction at the time of transfusion (bedside), due to the many variables associated with such practice and the difficulty in performing adequate quality control. To determine the adaptability of collection systems containing in-line filters to the current blood collection strategy, the feasibility, efficiency, and quality of before-storage WBC reduction of whole blood (WB) units were evaluated, following their prolonged storage at ambient temperature prior to component preparation, by use of an integral in-line filter. STUDY DESIGN AND METHODS: Blood was collected from random donors into quadruple blood pack units with an integral in-line filter and divided into three groups, according to storage conditions. WBC reduction was performed at room temperature, on WB units after storage at ambient temperature either for less than 8 or up to 18 hours on 1,4-butanediol cooling trays or for 18 hours in the cold. RESULTS: All the filtration procedures met the AABB threshold of less than 5 x 10(6) residual WBCs per unit and the European requirements for WBC counts of less than 1 x 10(6) WBCs per unit. The average filtration time was less than 22 minutes in all units studied. Filtration time and blood flow rate were both significantly longer, and RBC loss was significantly higher in WB units that were filtered after prolonged storage in the cold. CONCLUSIONS: Adequate before-storage WBC reduction can be achieved when performed on WB units, which were stored at ambient temperature for 18 hours, by use of an in-line filtration system. The procedure, performed under relatively simple logistics, results in good-quality, standard components, which require no further modifications when supplied to the transfusion services.

Adult↗
PubMed1985

Effect of blood glucose control on increased glomerular filtration rate and kidney size in insulin-dependent diabetes.

To investigate the relation between blood glucose control on the one hand and an increased glomerular filtration rate and enlarged kidneys on the other, we studied 12 patients with insulin-dependent diabetes and an increased glomerular filtration rate for a year after they were randomly assigned either to continuous subcutaneous insulin infusion or to unchanged conventional therapy. Glycemic control, measured by mean plasma concentrations of glucose and glycosylated hemoglobin, was rapidly and significantly improved (P less than 0.001) in the pump group but did not change in the conventional-treatment group. In the pump group, the glomerular filtration rate fell significantly in the study period (P less than 0.001) and became normal in four of the six patients. It did not change in the conventional-treatment group. There was no change in kidney volume in either group. At the end of a year, a return to conventional insulin treatment in the pump group resulted in both metabolic deterioration and a significant rise in the mean glomerular filtration rate toward base-line values. We conclude that in patients with established insulin-dependent diabetes, strict glycemic control normalizes the glomerular filtration rate, although the kidneys may remain enlarged.

Adult↗
PubMed2003

Use of hollow fiber membrane filtration for the removal of DMSO from platelet concentrates.

It has been hypothesized that, in addition to freezing injury, some damage to platelets may result from the cell packing that occurs during removal of the cryoprotectant. This study examined DMSO removal by fluid exchange across hollow-fiber (HF) filters as an alternative to centrifugation. The DMSO solution with or without cell suspension was passed once through the filter. The optimum exchange during unloading of DMSO was determined by varying the flow rates in the external and internal compartments of the HF filter. Initially, buffered solutions of a 5% DMSO solution in the absence of platelets were pumped into the fibers and exchanged against PBS. The residual DMSO was determined by osmometry. The exchange of DMSO across the membrane was flow dependent and also influenced by the chemical nature of the HF fibers. No protocol using a reasonable rate flow through the fibers removed more than 95% of the DMSO in a single pass. The optimum protocol was achieved with polysynthane fibers with an internal flow rate of approximately 20 mi/min and an external flow rate of 100 ml/min. Subsequently, frozen/thawed platelet concentrates in DMSO were washed using centrifugation and compared to the HF filtration method. Platelet quality was assayed by flow cytometry, cell count, morphology and osmotic stress test. Both filtration and centrifugal washing techniques resulted in comparable morphological scores and numbers of discoid cells. When agents reducing platelet activation were added, platelet quality was improved after washing by either technique. The lower platelet osmotic response with HF filtration than with centrifugation while using activation inhibitors was attributed to the remaining amount of the inhibitors. All other parameters tested were similar. The expression of CD62P was equivalent with both techniques, and centrifugation did not activate platelets more than filtration contrary to what was originally anticipated. In conclusion, platelet quality was comparable after washing by either technique but hollow fiber filtration does remove cryoprotectant more rapidly than does centrifugation.

Blood Platelets↗
PubMed2006

The role of ozonation and activated carbon filtration in the natural organic matter removal from drinking water.

Aquatic natural organic matter is one of the most important problems in the drinking water treatment process design and development. In this study, the removal of the natural organic matter was followed both in the full-scale drinking water treatment process and in the pilot-scale studies. The full-scale process consisted of coagulation, flocculation and flotation, sand filtration, ozonation, activated carbon filtration and disinfection. The aim of the pilot study was to investigate the influence of the dose and contact time of ozonation, and also the impact of activated carbon filtration, on the removal efficiency of organic matter. Several methods, including high-performance size-exclusion chromatography, total organic carbon content and assimilable organic carbon content measurements were used to characterize the behaviour of organic matter and its removal efficiency. On the full-scale process, total organic carbon was removed by over 90 %. According to size-exclusion measurements, chemical coagulation removed the high molar mass organic matter with an efficiency of 98%. The ozonation further removed the smaller molar mass fraction compounds by about 27%, while residual higher molar mass matter remained quite unaltered. Activated carbon filtration removed primarily intermediate and low molar mass organic matter. In the pilot-tests, conducted with sand filtered water from the full-scale process, it was noticed, that the ozonation removed primarily smaller organic compounds. The amount of assimilable organic carbon increased with increasing ozone dose, up to 0.4 mg l(-1) with the highest ozone dose of 4.0 mg 1(-1). The activated carbon filtration removed the assimilable organic carbon. Total organic carbon content was not reduced in ozonation.

Carbon↗
PubMed1998

Performance of N95 respirators: filtration efficiency for airborne microbial and inert particles.

In 1995 the National Institute for Occupational Safety and Health issued new regulations for nonpowered particulate respirators (42 CFR Part 84). A new filter certification system also was created. Among the new particulate respirators that have entered the market, the N95 respirator is the most commonly used in industrial and health care environments. The filtration efficiencies of unloaded N95 particulate respirators have been compared with those of dust/mist (DM) and dust/fume/mist (DFM) respirators certified under the former regulations (30 CFR Part 11). Through laboratory tests with NaCl certification aerosols and measurements with particle-size spectrometers, N95 respirators were found to have higher filtration efficiencies than DM and DFM respirators and noncertified surgical masks. N95 respirators made by different companies were found to have different filtration efficiencies for the most penetrating particle size (0.1 to 0.3 micron), but all were at least 95% efficient at that size for NaCl particles. Above the most penetrating particle size the filtration efficiency increases with size; it reaches approximately 99.5% or higher at about 0.75 micron. Tests with bacteria of size and shape similar to Mycobacterium tuberculosis also showed filtration efficiencies of 99.5% or higher. Experimental data were used to calculate the aerosol mass concentrations inside the respirator when worn in representative work environments. The penetrated mass fractions, in the absence of face leakage, ranged from 0.02% for large particle distributions to 1.8% for submicrometer-size welding fumes. Thus, N95 respirators provide excellent protection against airborne particles when there is a good face seal.

Aerosols↗
PubMed2005

Test for the integrity of environmental tractor cab filtration systems.

Cab filtration systems can be used to protect vehicle operators from hazardous air contaminants. In a cab filtration system, a fan draws air through filters and pressurizes the cab with this filtered air. This article describes the application of a low-cost, optical particle counter to evaluate the performance of tractor cab filtration systems. The tractors were equipped with environmental enclosures to protect the operators from pesticide exposures that occur during air blast spraying in orchards. Prior to testing, all environmental tractor cabs underwent a complete maintenance overhaul followed by a careful inspection by the manufacturer's field representative. As part of this maintenance effort, 13 tractors with cab filtration systems were tested in an enclosure. A Met One model 227B two-channel optical particle counter was used to measure the aerosol concentration outside and inside the cab. Ambient aerosol and/or aerosol generated by burning incense sticks were used to challenge the stationary cab filtration system in an enclosure. The ratio of the outside to inside concentration (Co/Ci) is the exposure reduction attained by the cab system. Alternatively, the inside concentration divided by the outside concentration times 100 (Ci/Co x 100) gives the percent penetration. All 13 tractors were tested for leak sites. Leak sites were identified and sealed. This process was repeated until each cab showed an exposure reduction ratio Co/Ci of at least 50 (aerosol penetration into the cab Ci/Co x 100 was less than 2%) at the 0.3-0.5 microm particle size interval.

Aerosols↗
PubMed1998

Effect of inline filtration on ViaSpan cold-storage solution.

The effect of filtration on the particulate load in ViaSpan cold-storage solution was studied. Commercially available inline blood transfusion filters (SQ40S, Pall Biomedical) were inserted into the delivery-set port of polyvinyl chloride bags of ViaSpan (DuPont Merck Pharmaceutical). Particles in samples collected in particle-free vials before and after filtration were counted by a light-obscuration technique. The compatibility of key ViaSpan ingredients and of three commonly used additives (penicillin G potassium, dexamethasone sodium phosphate, and human insulin) with the inline filter was also investigated. Filtration removed 56% of particles 5-10 microm in diameter, 71% of particles of > 10-25 microm, and > 99% of particles measuring > 25 microm. Flow rates with the filters were more than adequate for clinical use. Concentrations of constituent hydroxyethyl starch, glutathione, adenosine, allopurinol, raffinose pentahydrate, and lactobionic acid were not significantly affected by filtration, nor were the concentrations of any of the drug additives. Inline filtration of ViaSpan effectively reduced fatty acid salt particulates in the solution and had no deleterious effect on flow rate, ingredient concentrations, or concentrations of commonly added drugs.

Adenosine↗
PubMed1997

Glass wool column filtration, an advantageous way of preparing semen samples for intracytoplasmic sperm injection: an auto-controlled randomized study.

The characteristics of the glass wool filtration technique for the preparation of semen samples in an intracytoplasmic sperm injection programme (ICSI) were compared with a two-layer Percoll density gradient procedure. Half of each of 25 semen samples were prepared by each technique. The oocytes from each patient were randomly injected, half with spermatozoa prepared by glass wool filtration and half with Percoll-separated spermatozoa from the same semen sample. The percentage of recovered motile spermatozoa, the total motile sperm count, the percentage of morphologically normal forms, the fertilization rate, the cleavage rate and embryo quality obtained with both preparations were analysed. The 95% confidence intervals obtained through the Altman-Bland analysis showed that the percentage of motile spermatozoa recovered was 3.5-9.9% higher with the glass wool filtration technique, and this was highly correlated (r = 0.92, P = 0.0001) to the method. Similarly, the total number of spermatozoa available for ICSI was 0.18 x 10(6)-2.44 x 10(6) higher with the glass wool column and was highly correlated to the method (r = 0.956, P = 0.0001). Also, the percentage of normal forms was 1.25-3.31% higher after glass wool filtration but was poorly correlated to the method (r = 0.47, P = 0.017). Out of 100 metaphase II oocytes injected with glass wool-extracted spermatozoa, 77 fertilized and 72 cleaved. Out of 97 metaphase II oocytes injected with Percoll-selected spermatozoa, 71 fertilized and 69 cleaved. These results were not statistically different. The mean +/- SEM embryo quality score for the glass wool group (2.90 +/- 0.27) was the same as that for the Percoll group (2.80 +/- 0.24). No fertilization failures occurred and 11 patients (44% per oocyte retrieval) became pregnant. It was concluded that glass wool filtration for semen preparation in an ICSI programme offers higher sperm recovery and sperm morphology of superior quality than with the classic two-layer Percoll gradient method, without affecting the fertilization rate and embryo quality.

Cell Separation↗
PubMed1999

Intra- and interoperator variations in region-of-interest drawing and their effect on the measurement of glomerular filtration rates.

PURPOSE: Quantitative results are often obtained from images after drawing regions of interest (ROIs) about the organ or area being evaluated. The accuracy and reproducibility of ROIs is an important aspect of quality-control protocols. Attempts to increase ROI accuracy and precision by generating them automatically must be compared with manually processed images to evaluate the success of the automatic methods. Operators' abilities to reproduce ROIs and the effect this has on the reproducibility of estimating glomerular filtration rate from renograms were assessed. METHODS: Estimation of the glomerular filtration rate using Sampson's method requires a) exclusion ROIs around both kidneys for background subtraction, b) whole-kidney ROIs, and c) exclusion ROIs for the collecting system. Two nuclear medicine professionals were asked to produce glomerular filtration rate estimates for 20 patients with diverse renal function. This was repeated 1 month later. The intra- and interoperator variations were calculated for the glomerular filtration rate results and on a pixel basis for the ROIs. RESULTS: THE percentage of common pixels, on average, for a) intraoperator repeats and b) interoperator comparisons were a) 95%, 94%, 85%, and b) 94%, 93%, and 81% for region types 1, 2, and, 3, respectively. Analysis of variance for the glomerular filtration rate estimates showed significant variations in estimates for left kidneys (P < 0.025) but none (P > 0.1) for right kidneys. CONCLUSION: Spatial reproducibility in ROI drawing does not necessarily relate directly to the associated quantitative reproducibility.

Glomerular Filtration Rate↗
PubMed2004

Time to complete mixing for the measurement of glomerular filtration rate from single bolus plasma 51Cr-EDTA clearance.

BACKGROUND AND METHOD: In the measurement of glomerular filtration rate from the plasma clearance of 51Cr ethylenediamine tetraacetic acid by using the slope-intercept method, the first sample is conventionally taken at 2 h, the time by which it is generally assumed that the clearance curve has reached a single exponential. We examined this assumption by comparing the slopes, alpha 12 and alpha 23, based, respectively, on samples at 2 and 3 h, and at 3 and 4 h. RESULTS: In 421 patient studies in whom the first sample was taken between 110 and 130 min after injection, the mean ratio, alpha 12/alpha 23, was 1.101 (SEM 0.011) which is significantly higher than unity (P<<0.001). The relationship between alpha 12/alpha 23 and the slope, alpha 13 (which is a measure of filtration function already indexed for body size) based on all three samples was negative. By modelling the relationship between mixing time and alpha 13 it was shown that this relationship suggests delayed mixing of the indicator throughout its distribution volume and is inconsistent with irreversible binding of indicator to plasma protein. A significant positive association was observed between alpha 12/alpha 23 and age, but this is largely explained by a generally poorer filtration function in the older age group since low levels of alpha 13 theoretically predict a longer mixing time. In 188 patient studies in whom the first sample was taken more than 130 min after injection, the mean ratio, alpha 12/alpha 23, was 1.055 (SEM 0.017) which is still significantly higher than unity (P<<0.005) but significantly less than the ratio based on studies in which the first sample was taken at 110-130 min (P<0.02). The ratio alpha 12/alpha 23 still showed a significant relation (positive) with age but not with filtration function. CONCLUSION: This error in the estimation of glomerular filtration rate to which delayed mixing leads will make its greatest impact when using the simplified slope-only technique, but can be minimized by delaying the first blood sample.

Adolescent↗
PubMed2000

Effect of hypothermic pulmonary artery flushing on capillary filtration coefficient.

BACKGROUND: We previously demonstrated that surfactant dilution and inhibition occur immediately after pulmonary artery flushing with hypothermic modified Euro-Collins solution. Consequently, we speculated that increased capillary permeability contributed to these surfactant changes. To test this hypothesis, we evaluated the effects of hypothermic pulmonary artery flushing on the pulmonary capillary filtration coefficient (Kfc), and additionally performed a biochemical analysis of surfactant. METHODS: We used a murine isolated, perfused lung model to measure the pulmonary capillary filtration coefficient and hemodynamic parameters, to determine the wet to dry weight ratio, and to evaluate surfactant by biochemical analysis of lung lavage fluid. We defined three study groups. In group I (controls), we harvested lungs without hypothermic pulmonary artery flushing, and measured Kfc immediately. In group II (in situ flush), we harvested lungs after hypothermic pulmonary artery flushing with modified Euro-Collins solution, and then measured Kfc. Experiments in groups I and II were designed to evaluate persistent changes in Kfc after pulmonary artery flushing. In group III (ex vivo flush), we flushed lungs ex vivo to evaluate transient changes in Kfc during hypothermic pulmonary artery flushing. RESULTS: Groups I and II did not differ significantly in capillary filtration coefficient and hemodynamics. Group II showed significant alterations on biochemical surfactant analysis and a significant increase in wet-to-dry weight ratio, when compared with group I. In group III, we observed a significant transient increase in capillary filtration coefficient during pulmonary artery flushing. CONCLUSIONS: Hypothermic pulmonary artery flushing transiently increases the capillary filtration coefficient, leads to an increase in the wet to dry weight ratio, and induces biochemical surfactant changes. These findings could be explained by the effects of hypothermic modified Euro-Collins solution on pulmonary capillary permeability.

Airway Resistance↗