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At least 19 recordsLinked to original sources
PubMed2002

Prestorage WBC filtration of RBC units with soft-shell filters: filtration performance and impact on RBCs during storage for 42 days.

BACKGROUND: The introduction of universal WBC filtration of RBCs prior to storage is currently under consideration in many countries, as it is thought to minimize the incidence of transfusion-associated adverse effects. Centrifugation of blood containers with newly developed soft-shell WBC filters is more convenient, and so of great interest. STUDY DESIGN AND METHODS: Two different quadruple blood pack systems with integrated soft-shell WBC filters were compared (Sepacell OptiPure RC, Baxter Biotech, vs. LCR 5, Maco Pharma). Buffy coat-depleted RBC units were investigated from whole-blood donations that were held for 2 to 3 hours before centrifugation and subsequent filtration at 22 degrees C (Group 1, OptiPure RC, 450 mL; Group 2, LCR 5, 450 mL; Group 3, OptiPure RC, 500 mL; Group 4, LCR 5, 500, mL, n = 12 per group). Filtration performance was analyzed, and the impact of WBC filtration on hemolysis rate, Hb content, pH, supernatant potassium, ATP, and 2,3 DPG was investigated weekly during storage for 42 days. RESULTS: Filtration reduced the WBC count by 4.4 to 5.1 log. Mean +/- SD Hb content was 44.7 +/- 3.0, 41.2 +/- 3.3, 53.1 +/- 5.0, and 51.5 +/- 6.3 g per unit, respectively, with a corresponding mean RBC recovery after filtration of 71.0 +/- 3.0, 68.3 +/- 3.3, 76.6 +/- 1.7, and 68.9 +/- 4.5 percent. WBC filtration resulted in a significant reduction of Hct (0.10-0.14) in all four groups. Investigation of all RBC storage variables revealed acceptable values throughout the storage for 42 days. CONCLUSION: WBC filtration with two newly developed soft-shell filters showed acceptable WBC-reduction efficacy without any difference between filter types in buffy coat-depleted RBCs from 450- and 500-mL whole-blood donations. However, the application of both filters resulted in an unacceptably low RBC recovery after filtration, which was particularly evident with the LCR5 filter. Our findings raise concern that WBC reduction with these filters may result in the production of RBCs with an inappropriately low Hb concentration.

2,3-Diphosphoglycerate↗
PubMed2001

Tracer studies in the rat demonstrate misdirected filtration and peritubular filtrate spreading in nephrons with segmental glomerulosclerosis.

In two genetic models of "classic" focal segmental glomerulosclerosis (FSGS), the Milan normotensive and the Fawn-hooded hypertensive rats, tracer studies were performed to test the hypothesis that misdirected glomerular filtration and peritubular filtrate spreading are relevant mechanisms that contribute to nephron degeneration in this disease. Two exogenous tracers, lissamine green and horse spleen ferritin, were administered by intravenous injection and subsequently traced histologically in serial kidney sections. In contrast to control rats, both tracers in kidneys of Milan normotensive and Fawn-hooded hypertensive rats with established FSGS were found to accumulate extracellularly at the following sites: (1) within tuft adhesions to Bowman's capsule and associated paraglomerular spaces, (2) at the glomerulotubular junction contained within extensions of the paraglomerular spaces onto the tubule, and (3) within subepithelial peritubular spaces eventually encircling the entire proximal convolution of an affected nephron. This distribution strongly suggests the existence of misdirected filtration into tuft adhesions to Bowman's capsule and subsequent spreading of the filtrate around the entire circumference of a glomerulus and, alongside the glomerulotubular junction, onto the outer aspect of the corresponding tubule. This leads to an interstitial response that consists of the formation of a barrier of sheet-like fibroblast processes around the affected nephron, which confines the filtrate spreading and, subsequently, the destructive process to the affected nephron. No evidence was found that either misdirected filtration and peritubular filtrate spreading themselves or the associated tubulo-interstitial process led to the transfer of the injury from an affected nephron to an unaffected nephron. It is concluded that in the context of FSGS development, misdirected filtration and peritubular filtrate spreading are important damaging mechanisms that underlie the extension of glomerular injury to the corresponding tubulointerstitium, thus leading finally to degeneration of both the glomerulus and the tubule of a severely injured nephron.

Animals↗
PubMed1988

A strong correlation between glomerular filtration rate and filtration surface in diabetic nephropathy.

Quantitative structural studies were performed in kidney biopsy specimens from 24 long-term Type 1 (insulin-dependent) diabetic patients with persistent albuminuria due to diabetic glomerulopathy. Ten patients were receiving antihypertensive treatment, and among the remaining patients the mean blood pressure was 142/91 mm Hg (SD = 11/9). The urinary albumin excretion rate showed a range from 100 to 5494 micrograms/min (geometric mean 688 micrograms/min.) Glomerular filtration rate also showed a wide range, from supranormal to markedly decreased values (128 to 28 ml.min-1. (1.73 m2)-1, mean 75). The filtration surface (interface between capillary and urinary space) per total number of nephrons (open + occluded) was estimated by combined light-and electron microscopy. The percentage occluded glomeruli as well as structural quantities in the open glomeruli were taken into account in this estimate. A highly significant correlation was seen between glomerular filtration rate and filtration surface per nephron (r = 0.77, p less than 10(-4). The percentage occluded glomeruli contributed significantly to the variation in glomerular filtration rate (for this relationship tested separately r = -0.78, p less than 10(-5). The volume of open glomeruli was even larger than that seen in early diabetic glomerular hypertrophy and tended to increase with the percentage of glomerular closure, indicating that a compensatory hypertrophy might have taken place. In the open glomeruli the filtration surface constituted a smaller percent of total capillary surface (the remaining part facing the mesangial regions) than in early diabetic patients and control subjects. Our study has demonstrated that reduced glomerular filtration surface is closely associated with reduced glomerular filtration rate in Type 1 diabetic patients with diabetic nephropathy.

Adult↗
PubMed1992

Rapid filtration assays for protein kinase C activity and phorbol ester binding using multiwell plates with fitted filtration discs.

In the conventional approach protein kinase activity and phorbol ester binding associated with protein kinase C (PKC) are measured by initially incubating samples in either test tubes or multiwell plates, followed by filtration of the terminated reaction mixture using either a manifold filtration device or a cell harvester. Here we report a method in which both the incubations and filtrations necessary for the determination of either protein kinase activity or phorbol ester binding are carried out in the same multiwell plate with fitted filtration discs made of polyvinylidene difluoride (Durapore membrane). Due to the very low binding of protein to these filters, there is no interference caused by these filters during the incubation period of the assays. The drawback with these filters compared to commonly used cellulose acetate membrane filters is that they retain less of the phosphate acceptor substrate histone H1 (only 15%) if filtered and washed with standard 5% trichloroacetic acid. However, this can be overcome by increasing the trichloroacetic acid concentration to 25% during filtration. For phorbol ester binding determinations, the samples are incubated with [3H]phorbol 12,13-dibutyrate in the microwells, the ligand bound PKC is adsorbed onto DEAE-Sephadex beads, and the beads then are filtered and washed in the same microwells. Furthermore, this multiwell filtration approach can also be adopted to previously described cytosolic phorbol ester receptor assays, which have the broader conditions for optimal binding to receptors. Durapore membrane filters are found to work well for punching into scintillation vials and there is complete recovery of the radioactivity retained with the filters. In the protein kinase assay the background radioactivity is very low (< 200 cpm) and in the phorbol ester binding assay the nonspecific binding is less than 1%. Thus, these low background values result in at least a fourfold increase in sensitivity for these assays. Since the incubations and filtrations are carried out in the same well without any transfer of the sample, the coefficient of variation in multiple determinations is found to be low. Furthermore, this method is rapid and more convenient for analyzing a larger number of samples than conventional methods which use test tubes, and it is less expensive to set up compared to the automated methods that use a cell harvester.

Animals↗
PubMed1998

Fluid filtration across the arterial wall under flow conditions: is wall shear rate another factor affecting filtration rate?

The effect of flow on fluid filtration across an arterial wall was investigated in the canine common carotid artery. The arteries were cannulated in situ to maintain their in vivo length and endothelium intact. The excised vessels were pressurized at 120 mmHg through an overflow head-tank system that provided a constant flow rate to the perfused vessels. Filtration rates across the walls of the carotid arteries tested were measured under 4 different experimental conditions: 1) albumin-free Krebs solution under absent flow condition; 2) albumin-free Krebs solution with flow (148 +/- 8 ml/min); 3) Krebs solution containing 1.0 g/dl bovine serum albumin under absent flow condition; 4) Krebs solution containing 1.0 g/dl bovine serum albumin with flow (148 +/- 8 ml/min). Under absent flow conditions, the addition of albumin to the Krebs solution (1.0 g/dl) led to an approximate 25% drop in filtration rate (p < 0.001). It was found that fluid flow affected the filtration rate of the albumin solution, yet failed to affect the filtration rate of albumin-free solution across the arterial wall. The present study suggests that the change in filtration rate of the albumin solution under flow condition may indicate the change in the luminal surface concentration of albumin due to flow.

Animals↗
PubMed1971

Effective glomerular filtration pressure and single nephron filtration rate during hydropenia, elevated ureteral pressure, and acute volume expansion with isotonic saline.

Free-flow and stop-flow intratubular pressures were measured in rats with an improved Gertz technique using Landis micropipets or a Kulite microtransducer. In hydropenia, average single nephron glomerular filtration rate was 29.3 nl/min, glomerular hydrostatic pressure (stop-flow pressure + plasma colloid osmotic pressure) was 70 cm H(2)O and mean glomerular effective filtration pressure was 12.7-14.3 cm H(2)O, approaching zero at the efferent end of the glomerulus. Thus, the glomerulus is extremely permeable, having a filtration coefficient four to five times greater than previously estimated. Mean effective filtration pressure and single nephron glomerular filtartion rate fell with elevated ureteral pressure and rose with volume expansion, more or less proportionately. Changes in effective filtration pressure were due primarily to increased intratubular pressure in ureteral obstruction and to reduced plasma colloid osmotic pressure in volume expansion; glomerular hydrostatic pressure remained constant in both conditions and thus played no role in regulation of filtration rate.

Animals↗
PubMed1989

Complement activation in plasma exchange by single filtration and centrifugation and in cascade filtration.

C3d was assayed in samples of blood plasma obtained before and after centrifugation, single filtration or cascade filtration, and also in samples of waste plasma obtained after termination of exchange. In blood plasma, cascade filtration was followed by an increase of the mean C3d concentration from 20 to 50 mU/l (p less than 0.001, n = 15), whereas single filtration and centrifugation were followed by a minor decrease. Waste plasma of cascade and single filtration contained 113 +/- 42 mU/exchange (n = 15, mean +/- SD) and 83 +/- 46 mU/exchange (n = 8), respectively. In centrifugation, the concentration of C3d of waste plasma never exceeded that of blood plasma, and the total amount of C3d of waste plasma was only 4 +/- 6 mU/exchange. In contrast to filtration, the centrifugation technique seemed not to be afflicted with any increase in the break down of complement component C3.

Blood Proteins↗
PubMed1980

A strong correlation between glomerular filtration rate and filtration surface in diabetic kidney hyperfunction.

The direct relationship between glomerular filtration surface and glomerulaf filtration rate was studied in a group of eight short term, young diabetics exhibiting a 50 per cent elevated glomerular filtration rate with a 2-fold variation within the group. A close correlation was obtained between glomerular filtration surface and glomerular filtration rate, r = 0.8. This supports the idea that the increase in glomerular capillary surface may be a main factor in diabetic kidney hyperfunction. The possible long term implications of the functional and morphologic abnormalities are discussed.

Adult↗
PubMed1988

Correlation between single nephron glomerular filtration rate and filtration area in superficial glomeruli of developing rats.

Single nephron glomerular filtration rate (SNGFR) was correlated to the area of the glomerular basement membrane (GBM) determined by stereological techniques in rats between 20 and 40 days of age. Single nephron glomerular filtration rate increased 8.4 times in parallel with a twofold increase in GBM area. The much greater postnatal increase in SNGFR than in GBM area demonstrates that the increase in GBM area cannot account for the entire increase in SNGFR. Instead a combination of other factors influencing SNGFR most likely determines the largest part of the increase in SNGFR during this period. Thus, the drop in vascular resistance known to occur during maturation will increase the renal blood flow and may cause the filtration process to turn from a state of filtration equilibrium to or close to disequilibrium, thereby increasing GFR. Additional increase in GFR may be due to an increased net driving force for filtration and/or changed hydraulic permeability.

Age Factors↗
PubMed1990

Treatment efficiency and filtration rate of a horizontal sand filtration system.

The purpose of this study was to establish acceptable criteria for a horizontal sand filtration (HSF) system that are suitable for the design of community water supply units in rural areas. Two laboratory scales of HSF were constructed and tested for their filtration rates and treatment efficiency in Visetchaicharn District of Angthong Province, Thailand. The main structure of both models was the same except for the lengths of the filtration column, i.e., 80 cm. in Model 1 and 100 cm. in Model 2. The results of treatment efficiency of both models were very satisfactory. The physical and chemical quality of the filtered water was within the standards for drinking water except for bacteria quality. The rates of filtration of Model 1 were slightly faster than those of Model 2 for both one and two meters of water level in the raw water column. The rates for both models were higher than the lower limit standards of the slow sand filtration system throughout the study.

Filtration↗
PubMed1992

[RoTrac capillary pore membranes for laboratory filtration. I. Degermination filtration].

RoTrac capillary pore membranes (CPM) are produced by means of the nuclear track technology. Thus a defined and in wide ranges independent adjunction of the different membrane parameters (diameter, density, shape and inclination of pores) is possible. The wanted uniform separation diameter of the membrane can exactly be chosen according to the size of the microorganisms to be rejected. By dead end filtration experiments with E. coli and Serratia marcescens the suitability of RoTrac-CPM in bacteria removal filtration was proven. Blocking was very strong for membranes with pore diameters in size range of the microorganisms (approximately 0.45 micron). Though the filtrate had immense reduced bacteria counts (from 10(7)-10(8) to 10-100 bacteria/ml), it was generally not sterile. For membranes with a pore diameter of 0.2 micron and smaller blocking was essentially lesser. Here filtrate was always sterile. Flux (and thus the filterable volume) corresponds to values of competitive membranes. Compared with those the proven possibility of simple cleaning is an advantage, because rejection and blocking of symmetrical CPM occur directly on the membrane surface. This is promising for use of CPM in cross flow filtration.

Disinfection↗
PubMed1992

[RoTrac capillary pore membranes for laboratory filtration. II. Bacteria-free filtration].

Because of their special characteristics Capillary pore membranes (CPM) are now applied in several branches of separation techniques and analytics. Besides applications in particle analytics and microfiltration of different media capillary pore membranes can be used in microorganism separation. It was shown that RoTrac CPM can be used for bacteria free (or so called sterile) filtration. Acceptable fluxes were reached in separation of Pseudomonas diminuta (test species ATCC 19146). Membranes with pore diameters of 0.2 micron and smaller always assure a bacteria free filtrate even for a very high bacteria count of about 10(7)-10(8) bacteria/ml. In filtration of Mycoplasma arginini no sterile filtrate was obtained for a pore diameter of 0.08 micron and a high bacteria count of 3 * 10(7) bacteria/ml. The bacteria rejection by a factor of 10(5) was however remarkable. Only for 0.05 and 0.08 micron with reduced bacteria load the filtrate was bacteria free.

Colony Count, Microbial↗
PubMed1991

Dynamic filtration of blood: a new concept for enhancing plasma filtration.

We have shown previously that blood flow pulsations created by intermittent squeezing of the inlet blood line significantly increased the plasma filtration rate in membrane plasmapheresis. However, in order to avoid hemolysis, the filtration increase had to be limited to about 50%. We have now devised a more efficient pulsation generator. By properly matching the tubing compliance and the pulsation amplitude, it is possible to extract 50 ml/min of plasma from 90 ml/min of blood at 36% hematocrit with a 1000 cm2 polypropylene hollow fiber filter without hemolysis. Simultaneous recording of the time course of plasma filtration rate measured by an electromagnetic flow meter and transmembrane showed that the increase in mean plasma flow rate was due to a dynamic filtration process which prevents the establishment of concentration polarization. The transmembrane pressure (Ptm) increases over a 0.5-second interval when the tube is squeezed. The membrane responds with an increase in filtration since the concentration polarization layer takes a few seconds to build up. The Ptm then drops when the tube is released before the polarization layer has time to build up appreciably and a sudden acceleration of the blood flow (velocity spike) helps clean the membrane, reducing the polarization. Tests with bovine show that the system is very efficient in reducing membrane plugging with small area filters.

Animals↗
PubMed1993

The role of synovial fluid filtration by cartilage in lubrication of synovial joints--II. Squeeze-film lubrication: homogeneous filtration.

A mathematical model of synovial film filtration and synovial gel formation at normal approach of cartilage surfaces in the human hip joint is presented. The biphasic mixture model presented in Part I of this paper [Hlavácek, J. Biomechanics 26, (1993)] for synovial fluid and that of Mow and his collaborators [J. Biomech. Engng 102, 73-84 (1980)] for cartilage are used. A general analysis of filtration of an axially symmetric synovial squeeze-film between two cartilage layers at normal approach is given. The geometrically simple case much idealising the human hip joint is also considered: two cartilage discs with a synovial film in between are compressed by the steady loading of the half human weight. The homogeneous film filtration process where the synovial gap remains parallel and the macromolecular concentration in the gap is spatial homogeneous (to the thin-film approximation) and time-dependent is numerically analysed. If the hyaluronic acid concentration of the synovial gel at equilibrium is 50 mg/ml at least, the resulting stable gel layer thickness for the homogeneous filtration in the human hip joint and for normal synovial fluids is about 0.1 micron, being almost independent of the loading. Inflammatory synovial fluid shows values several times lower.

Adhesiveness↗
PubMed1978

Influence of glomerular filtration rate on renal PAH secretion rate in the rat kidney. Dependency of PAH extraction on renal filtration fraction.

PAH secretion (TPAH) was studied in rats at spontaneously occurring glomerular filtration rate (GFR). At saturated transport, TPAH was found to be correlated to GFR. This relationship was also observed at unsaturated transport where TPAH depends upon the PAH concentration in arterial plasma. However, no significant correlation between TPAH and renal PAH load or renal plasma flow rate was found when the effects of GFR were removed by partial correlation analysis. A dependency of TPAH on GFR explains the correlations found between filtration fraction (FF) and renal PAH extraction (EPAH) or renal tubular PAH extraction fraction (EPAH--FFPAH). Thus, even at low PAH concentration in a. plasma, renal PAH extraction may only be assumed to be constant if the filtration fraction is constant.

Aminohippuric Acids↗
PubMed1978

Simultaneous measurements of capillary diffusion and filtration exchange during shifts in filtration-absorption and at graded alterations in the capillary permeability surface area products (PS).

The diffusion exchange of Cr-EDTA, using the single injection indicator diffusion method, was followed simultaneously with estimations of the capillary filtration capacity (CFC) in an "isogravimetric" rat hindquarter preparation during artificial perfusion and maximal dilatation. Measurements were performed at constant flow and during 1) shifts in filtration-absorbtion, 2) alterations of perfused capillary wall area (graded rarification of capillary network by microsphere injection) and 3) during alterations of permeability (i.a. infusion of histamine). At maximal vasodilatation CFC was 0.037 +/- 0.001 ml/min X mmHg X 100 g and PS for Cr-EDTA 5.67 +/- 0.13 ml/min X 100 g. During filtration or absorbtion, Cr-EDTA transfer from vessels to interstitium changed only slightly but the situation may well be different for solute transfer from interstitium to vessels. Alterations in capillary wall area resulted in proportional changes in PS for Cr-EDTA while the CFC changes were always relatively smaller. Histamine increased CFC some threefold with a marked increase in protein transfer, while PS for Cr-EDTA increased only marginally. This histamine effect could be ascribed mainly to an increase in the number of large pores which, because of their relative paucity, are of little importance for small molecular diffusion exchange but highly important for convective and macromolecular exchange.

Absorption↗
PubMed1977

[Simultaneous determination of effective renal plasma flow and glomerular filtration rate using a double isotope technic--determination of the filtration fraction].

A method for the simultaneous determination of the effective renal plasma flow and of the glomerular filtration rate with the help of 131J-o-iodohippuric acid and 169Yb-DTPA using a double isotopic technique is described. Apart from this the method serves for the establishment of the filtration fraction. 40 patients with different clinical pictures (glomerulonephritis, pyelonephritis, cystic kidneys, stenosis of the renal artery) were examined. The clearance values established by us were in the areas characteristic for the clinical pictures. Pathological conditions could be established which are not yet characterized by an increase of the fixa of the urine in the serum. By the determination of the filtration fraction differential-diagnostically important insights are afforded. The examination is methodically simply to be performed and is of little stress for the patient. Therefore it seems to be suitable for the routine examination.

Glomerular Filtration Rate↗