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At least 1,027 records · Page 57Linked to original sources
PubMed1995

Effects of a K+ channel blocker on glomerular filtration rate and electrolyte excretion in conscious rats.

Effects of a K+ channel blocker on glomerular filtration rate and electrolyte excretion in conscious rats were observed. Effects of K+ channel modulation on glomerular filtration rate and electrolyte excretion were studied using the adenosine-triphosphate- (ATP)-sensitive K+ channel blocker 4-morpholinecarboximidine-N-1-adamantyl-N'-cyclohexylhydr ochloride (U-37883A) in conscious rats previously equipped with catheters for clearance studies. In saline-loaded rats, i.v. doses of U-37883A of 1.7, 5.0 and 15 mg/kg increased absolute and fractional Na+ excretion dose-dependently without changing K+ excretion. The glomerular filtration rate remained constant during diuresis. In water-loaded (hypotonic dextrose) rats, free-water clearance studies revealed that the ATP-sensitive K+ channel blocker significantly decreased an index of solute reabsorption (free-water clearance adjusted for chloride clearance) in the diluting segment during peak natriuretic activity. In addition, U-37883A significantly decreased the osmolality of renal papillary interstitial fluid, indicative of an effect in the medullary portion of the diluting segment. Together, these findings suggest that ATP-sensitive K+ channels, possibly those located at the apical boarder, play a pivotal role in Na+ reabsorption in the thick ascending limb of the loop of Henle.

Adamantane↗
PubMed1994

Lipid determination from monophasic solvent mixtures: influence of uneven distribution of lipids after filtration and centrifugation.

Reasons for the variation in erythrocyte lipid extraction were investigated. We found that there was an uneven distribution of lipids after filtration (up to 10% accumulated in the filtrates) or centrifugation (up to 10% in the top fraction) of several apparently monophasic extraction systems. The uneven distribution was more pronounced in the systems containing relatively more water, or, generally speaking, with more nonpolar solvents. Ill-defined procedures using either filtration or centrifugation, therefore, could be the cause for variations in lipid extraction. A way to prevent the uneven distribution has been developed and is discussed.

1-Propanol↗
PubMed1993

[Expression of proliferating cell nuclear antigen following filtration surgery in rabbits].

We evaluated cell replication in wound healing following experimental filtration surgery. Cell replication was measured via immunohistochemistry for proliferating cell nuclear antigen, which is a marker of cell proliferation. Trabeculectomy was performed on albino rabbit eyes, with the filtering site harvested on postoperative days 1, 4, 7, and 14. Samples were fixed with 10% buffered formalin and prepared for paraffin section, and proliferating cell nuclear antigen was detected in filtering site tissue using the labeled streptavidin-biotin method. The number of immunoreactive cells increased at days 4 to 7 and was markedly decreased at day 14; the filtering site was obstructed at days 7 to 14. These findings may have clinical implications for the administration of antiproliferative agents after filtration surgery. Evaluation of cell replication following filtration surgery by detecting proliferating cell nuclear antigen is a simpler technique than autoradiography.

Animals↗
PubMed1994

Effects of glucagon on diuresis, renal plasma flow and glomerular filtration in sheep.

The effects of intravenous infusion of glucagon (100 ng.kg-1.min-1) on diuresis, renal plasma flow and glomerular filtration rate were studied in conscious sheep. Diuresis began to decrease upon initiation of glucagon infusion, down to 50% of its baseline value at the end of glucagon infusion. Glomerular filtration rate was also decreased by 75%. With regard to renal plasma flow, the decrease started at the beginning of glucagon infusion, but remained restricted. It was not possible, from these results, to explain the reduced diuresis by a decrease in renal plasma flow; the observed anti-diuretic effect could be the consequence of a modification of either the filtration coefficient or water tubular reabsorption.

Animals↗
PubMedDate not supplied

Lipid peroxidation in platelet concentrates: effects of leukocyte removal by filtration.

Increased lipid peroxidation (LP) occurs in the presence of various transition, metal ions, including copper and iron, as well as various heme moieties. In addition, irradiation significantly increases LP. The degree of LP, as determined by the liquid chromatographic measurement of plasma malondialdehyde (MDA), can be significantly reduced by the addition of various metal chelating agents and other antioxidants to both stored red blood cells and platelet concentrates. They are also effective in reducing the degree of LP following irradiation. In the current study, leukocytes were effectively removed by filtration from platelet concentrates prepared by standard methods (mean +/- SD before filtration, 460 +/- 286 per microL vs 0.3 +/- 0.2 per microL after filtration). The removal of the white blood cells significantly reduced the plasma MDA levels in the leukocyte-free platelet concentrates compared with concentrates containing leukocytes after storage for 4, 7, and 11 days (P < 0.001; P < 0.02; P < 0.05, respectively). In addition, plasma potassium levels were also significantly reduced in the leukocyte-free platelet concentrates (P < 0.001). Our results suggest that the early removal of leukocytes from platelet concentrates may be helpful in prolonging platelet viability and longevity.

Blood Platelets↗
PubMedDate not supplied

Short term effect of an aldose reductase inhibitor on urinary albumin excretion rate (UAER) and glomerular filtration rate (GFR) in type 1 diabetic patients with incipient nephropathy.

OBJECTIVE: Increased activity of the enzyme aldose reductase in the polyol pathway, occurring with hyperglucaemia, has been implicated in the development of late diabetic complications. The effect of an aldose reductase inhibitor (Ponalrestat) on renal function in type 1 diabetes with incipient nephropathy (urinary albumin excretion rate > 20 micrograms.min-1) was evaluated. RESEARCH DESIGN AND METHODS: Thirty Type 1 diabetic patients (age: 34.4 +/- 3.1 yrs; diabetes duration 13.1 +/- 1.3 yrs) were treated with 600 mg of Ponalrestat per day for 3 months using a randomized double blind placebo controlled crossover design. Urinary albumin excretion rate and glomerular filtration rate were measured. RESULTS: Twenty three patients completed the entire study. Compared to placebo, there was no significant change in urinary albumin excretion rate and glomerular filtration rate during the Ponalrestat treatment period. Blood pressure and HbA1 were also unchanged during the placebo and Ponalrestat periods. Treatment with Ponalrestat appeared to be safe and there were no side effects. CONCLUSION: We conclude that three months aldose reductase inhibition with Ponalrestat had no effect on urinary albumin excretion rate and glomerular filtration rate in Type 1 diabetic patients with incipient nephropathy.

Adolescent↗
PubMed1977

Maintenance of low screen filtration pressure in blood stored in a new liquid medium: BAGPM.

Formation of microaggregates in blood stored in conventional media is reflected by rapidly rising screen filtration pressure (SFP). We show that the BAGPM (bicarbonate, adenine, glucose, phosphate, and mannitol) blood preservation system maintains SFP at near normal levels throughout the storage period of 42 days. Whenever the SFP had a tendency to rise in BAGPM blood, filtration through a routine in-line blood filter reverted SFP back to baseline levels. Blood from the same donors stored in citrate-phosphate-dextrose (CPD) adenine had a rapidly rising SFP by 7 to 14 days of storage. Filtration through the routine blood filter had no effect on the SFP of blood stored in CPD-adenine, CPD, or ACD. BAGPM not only maintains adequate levels of ATP and 2,3-diphosphoglyceric acid (2,3-DPG) during full 42 days of storage but also offers a unique system in which microparticulate material is prevented from forming, with maintenance of low SFP, perhaps because of its low leukocyte, platelet, and fibrinogen content.

Blood Preservation↗
PubMedDate not supplied

Loss of LDH activity during membrane filtration.

Membrane filters rendered hydrophilic and composed of biphenyl polycarbonate, polyvinylidene fluoride (PVDF), acrylic copolymer, polysulfone, and mixed esters of cellulose were evaluated to determine which type of filter best can be used for the filtration of lactate dehydrogenase (LDH) solution. Also, the effect of the membrane pore size was evaluated. LDH solution was passed through the filters at a controlled flow rate, after which the filtrate was assayed for LDH activity and protein content using the Bradford method. Polycarbonate and PVDF filters generally showed low loss of protein, except 5 microns PVDF filters. Mixed esters of cellulose, acrylic copolymer, and polysulfone caused considerable loss of protein during passage of the LDH solution through the filter. Interestingly, it was also found that, generally, as the pore size increased the amount of protein loss decreased. However, 5 microns PVDF and mixed esters of cellulose filters showed more loss than their corresponding 0.65 microns and 3 microns pore size filters, respectively. In all cases, more protein was recovered in the filtrate fractions as the volume of LDH solution filtered was increased, suggesting that the mechanism of loss is adsorption and that the magnitude of loss is related to saturation of the matrix polymer surfaces.

Adsorption↗
PubMedDate not supplied

Alteration of pulmonary function by filtration of intravenous nutrient mixture.

In view of contradicting results concerning alteration in lung function during hyperalimentation and the administration of intravenous lipid emulsion, a study was planned to determine possible changes in pulmonary blood perfusion during administration of total nutrient admixture (TNA) and the effect of filtration. Sixteen patients (8 men, 8 women; mean age 65.6 yr) with no previous lung disease received TNA at the rate of 4-5 g lipid/h as preoperative treatment for 5-9 days (mean 6.7 days). The 5-microns filter was randomly used in eight patients. The lung blood perfusion parameters measured repeatedly during this period included blood gases, percentage of the predicted value of vital capacity (VC), and pulmonary diffusing capacity for carbon monoxide (DLCO), as well as the value of the dead space volume and the tidal volume ratio (VD/VT) and the calculated shunt (QS/QT). TNA infusion appears to cause only a slight decrease in PaO2 and DLCO and a similar increase in VC and QS/QT, whereas VD/VT decreased significantly. The latter effect was abolished by filtration of TNA. There were no significant differences between the two groups. We therefore conclude that short-term preoperative administration of TNA at the rate of 4-5 g lipid/h in patients without preexisting lung disease does not jeopardize lung functions. Filtration of the TNA is, however, recommended to avoid the potential hazardous effects of long-term treatment of TNA on lung function.

Aged↗
PubMed1996

Filtration, centrifugation and mouse exposure for the detection of schistosome cercariae in water.

Three methods for detection of schistosome cercariae in water were studied under laboratory and simulated field conditions in Egypt. Water samples tested by filtration and centrifugation quantitatively reflected the density of cercariae in moderately turbid canal water (30 Nephelometry Turbidity Unites, NTU). When tested in waters of increasing turbidity, the centrifuge gave more consistent results than the filtration system. The centrifugation technique was more efficient in processing the water samples and took almost half the time of filtration. Mouse exposure was useful in detecting cercariae, but was not quantitative. However, there was a significant improvement in worm recovery when mice were more close together in the floatation device. Mouse exposure was also expensive and cumbersome to use. It appears from the present results that the technique of choice for further cercariometric work under Egyptian conditions may be centrifugation.

Animals↗
PubMedDate not supplied

In-line leukocyte filtration during bypass. Clinical results from a randomized prospective trial.

Leukocyte mediated pulmonary injury may delay recovery after cardiac surgery, and leukocyte depletion during bypass has been suggested. Two groups of patients were randomly, prospectively assigned from 50 sequential patients to undergo open heart surgery using cardiopulmonary bypass, either with (n = 25) or without (n = 25) leukocyte filters. The two groups were not significantly different regarding age, gender, race, pre-operative ejection fraction, pump time, or cross-clamp time. Post operative arterial blood gases (pO2: 173 +/- 66 vs 192 +/- 107; pCO2: 30.2 +/- 8.2 vs 30.8 +/- 8.0), pulmonary vascular resistance (PVR 105 +/- 45 vs 112 +/- 50 dyne cm-5), time on ventilator (17.8 +/- 6.4 vs 19.7 +/- 8.6 hr), and length of hospital stay (7.65 +/- 4.57 vs 8.52 +/- 5.87 days) were not different between groups (mean +/- SD, with vs without filters, respectively). Arterial oxygenation was somewhat poorer, and PVR was somewhat lower in the leukocyte filtered group. However, these trends did not produce significant decreases in total ventilator time or length of hospital stay. In-line filtration did remove leukocytes, but did not reduce circulating leukocyte count. In effect, leukocyte filtration produced an effective leukocyte concentration at the filter site. These data do not support routine incorporation of in-line leukocyte filtration during bypass.

Cardiac Surgical Procedures↗
PubMed1997

Analysis of 3H-proline-labeled protein by rapid filtration in multiwell plates for the study of collagen metabolism.

Quantitative and qualitative analysis of cell cultures labeled with 3H-proline for monitoring collagen synthesis is time-consuming and occasionally generates large quantities of radioactive waste. This present work describes the application of a microwell filtration system for the analysis of collagen metabolism in chondrocytes. It is based on trichloroacetic acid (TCA) precipitation of 3H-proline-labeled proteins onto polyvinylidene difluoride membranes fitted in a 96-well plate and subsequent analysis of precipitated proteins by liquid scintillation counting, amino acid analysis and sodium dodecyl sulfate (SDS) gel electrophoresis. This method allows for the initial processing of 96 samples within 2 h, has high sensitivity and accuracy (linearity > or = 200 cpm/sample) for quantitative measurements and a capacity of up to 10 micrograms collagen/microwell. The ratio of the radioactive protein collected by this filtration assay compared to that collected by molecular sieve chromatography on Sephadex G-25 was linear over a broad range, indicating full compatibility of data and a high reproducibility for both assay systems. The quality of protein separation by SDS-polyacrylamide gel electrophoresis (PAGE) from samples obtained by the filtration assay and by dialysis was virtually identical. These features make the assay particularly suited for pulse-chase experiments and for monitoring protein degradation.

Animals↗
PubMed1997

Monoclonal antibody detection of Clostridium microcolonies directly on membrane used for milk filtration.

The normal procedure for bacterial colony detection requires a nitrocellulose transfer step after membrane filtration and culture to prevent the development of a high background during the immunodetection. In this paper, we describe a modification of the basic protocol that omits the transfer step and reduces the risk of background. Previous observations indicated that interactions between milk components (principally cream) and membrane are responsible for the high non-specific staining observed. Experiments were performed to remove lipid components or to block the membrane binding sites before milk filtration. Samples of milks of different origin (collected at different times of the year) and different membranes were tested. The results obtained showed that removing lipids did not significantly improve the test but, on the contrary, led to an antigen diffusion. Incubation of the membrane in 0.1% (w/v) of Tween 20 in phosphate-buffered saline before milk filtration prevented non-specific binding, and allowed performance of the detection without any noticeable background.

Animals↗
PubMed1977

Effect of inline filtration of intravenous infusions on the incidence of thrombophlebitis.

The effect of inline filtration on the incidence of infusion phlebitis was examined in a community hospital. Two general surgical units, comparable in their patient populations, were studied during a one-month period. On one unit, an extension set with a 45 micrometer filter was attached to every i.v. catheter; no inline filtration was instituted on the second unit. The use or nonuse of a filter was not blinded. The filter was replaced every 24 hours or sooner if blockage occurred. A total of 49 patients (107 i.v.s) were studied in the group with filters and 40 patients (84 i.v.s) without filters. Phlebitis was graded on a scale of 0 to 4. The proportion of patients with phlebitis in the filter group was 86%; in the no-filter group, 75%. In the filter group, 67% of the catheterizations ended in phlebitis; in the no-filter group, 63%. Upon first catheterization, phlebitis developed in 63% of the filter group and 58% of the no-filter group. None of these differences was significant (p = 0.05). There was also no significant difference between the two groups in the severity of phlebitis and the incidence of phlebitis following the administration of irritating solutions containing cephalothin sodium or potassium chloride. Based on this study, the value of inline filtration in routine clinical conditions appears to be questionable.

Connecticut↗
PubMedDate not supplied

[Dynamics of the establishment of renal glomerular filtration in dogs during the early postnatal period].

By means of inulin clearance method, studies have been made on the glomerular filtration rate in 1-35-day puppies and adult dogs. The filtration rate was calculated per body weight, body surface, wet and dry weight of the kidney, wet and dry weight of the kidney cortex. It was found that dry weight of the kidney cortex is the best basis for comparison of the glomerular filtration in growing and adult organisms, as well as for the investigation of the development of this function.

Animals↗
PubMed1997

[Inline filtration of erythrocyte concentrates with the Leucoflex LCR4 T/B system].

The in-line-filtration of red cell concentrates (RCC) is an effective method to reduce white-cell-induced reactions. SAG-M RCCs were prepared in quadruple top/bottom bag systems and filtered after storage at 4 degrees C (study: n = 12). The mean white blood cell (WBC) reduction was 99.9% with the number of residual WBCs at about 0.67 x 10(6) per unit and with a loss of Hb mass of 10.64%. No cell fragments of WBCs and monocytes were detected (MAIPA). After storage of 42 days, mean values of hemolysis level (0.64%) and ATP concentration (2.27 mumol/g Hb) were improved compared with unfiltered RCCs. Comparably good results of leukocyte depletion were achieved by preparation of about 3,000 in-line filtrated RCCs for clinical use, measured by routine quality control (n = 25). Our experience shows that the systems are easy to handle and to use. The Leucoflex LCR4 in-line T/B system (Maco Pharma) can be recommended in the clinical practice by virtue of the effective leukocyte elimination, particularly in those blood banks with platelet concentrate production from buffy coats beside the RCC in-line filtration.

Equipment Design↗
PubMed1994

[Leukocyte filtration of stored whole blood for preparation of components].

Prophylaxis of infection and alloimmunisation is the main reason for leucocyte depletion by filtration of blood components. The question is whether all red cell concentrates (RCC) should be filtered and whether plasma has to be filtered, too. For leucocyte-poor units whole blood was filtered before preparation using the 'top and bottom' system. These units of buffy-coat-poor RCC and plasma were compared with components filtered after preparation. Non-filtered RCCs and plasmas served as a control. By prefiltration of whole blood and filtration of components we obtained RCCs and plasmas with less than 1 x 10(5) leucocytes in every unit. In conclusion, leucocyte filtration before preparation seems to be an easy and cost-effective method in order to get two filtered components (RCC and plasma) with one filter.

Blood Component Transfusion↗
PubMed1998

A cross-over pharmacokinetic study of a double viral inactivated factor IX concentrate (15 nm filtration and SD) compared to a SD factor IX concentrate.

A double blind randomized cross-over multi-center study has been conducted to compare the pharmacokinetic and coagulation activation markers of high-purity factor IX concentrate subjected to both solvent/ detergent (SD) treatment and 15 nm-filtration (FIX-SD-15) with the licensed product subjected only to solvent-detergent (FIX-SD). This filtration process allows the elimination of small particles, such as non-enveloped viruses (i.e., hepatitis A and parvovirus B19). Eleven severe hemophilia B patients (FIX coagulant activity <2 IU/dl) received one infusion of 60 IU/kg of FIX-SD and one infusion of 60 IU/kg of FIX-SD-15 at least at 10 days interval. Blood samples were obtained before and at various time up to 72 h after infusion. The decay curves of factor IX (FIX:C and FIX:Ag) were evaluated by a model independent method. Bioequivalence was found between the two concentrates using the Schuirmann test. The mean FIX:C and FIX:Ag recovery of FIX-SD-15 was 1.08 and 0.89 IU/dl/IU/kg respectively with a mean half-life of 33.3 h for FIX:C and 25.6 h for FIX:Ag. Six months after initial enrollment, pharmacokinetic parameters were similar in the 7 patients tested. There was no significant variation of prothrombin fragment 1+2 and thrombin-antithrombin complexes measured up to 6 h after infusion, indicating that there was no activation process after administration of FIX. In conclusion, these data demonstrate that the introduction of a 15 nm filtration does not alter the pharmacokinetic profile of a well characterized SD FIX concentrate while providing additional viral safety.

Adolescent↗