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At least 487 records · Page 27Linked to original sources
PubMed1984

Comparison of filtration to continuous-flow centrifugation for plasma exchange.

The Asahi Plasmaflo Hollow Nylon Fibre Filtration System (n = 13) was directly compared to the NCI-IBM 2990 Continuous-Flow Blood Fraction Separator (n = 10) for plasma exchange. The systems were equally efficient in achieving plasma separation. There were significant differences favouring filtration for clearance of fibrinogen (P less than 0.05), and the fourth component of complement (P less than 0.01). Greater loss of urea (P less than 0.05) was found after plasma exchange, using the cell separator. The flow characteristics were markedly different. In a standardised 4-L plasma exchange, filtration took place at 35 ml/minute, with a procedure time of 109 +/- 45 minutes in contrast to centrifugation at a plasma flow collection rate of 19 ml/minute, requiring 208 +/- 17 minutes. This time advantage for the former procedure was offset by 195 minutes required to regenerate the hollow nylon fibre unit and a further 90 minutes required for cleaning under strictly controlled aseptic techniques prior to reuse. Each filter was regenerated at least twice and reused without infection, but there was incremental loss of filtration efficiency demonstrated by decreasing clearance of an intravascular marker dye. In two of the 13 procedures using the Plasmaflo system, serious reactions necessitated termination of the procedure; this did not occur using the cell separator. Restriction of the number of times that the filter unit could be regenerated without loss of efficiency, the prolonged time required for regeneration and cleaning, coupled with the need for artificial vascular access to meet high blood flow rates required, limit the usefulness of this technique for plasma exchange.

Blood Chemical Analysis↗
PubMed1989

Technetium-99m radiochemical assay by rapid filtration: a superior alternative to chromatography.

A new method for simultaneously measuring radiochemical purity and estimated lung trapping of colloidal technetium-99m (99mTc) radiopharmaceuticals is described. The method employs a small filtration device comprised of two stacked membrane filters, differing in membrane composition and in pore size, situated over a filtrate collection vial. Specifically, an 8-microns pore polycarbonate membrane filter is situated above a 0.22-microns pore mixed-cellulose-esters membrane filter. For assay, a diluted aliquot of radiopharmaceutical is passed through the filtration device. Technetium-99m radioactivity on the membranes and in the vial is then measured. The polycarbonate filter traps and quantitates lung-capillary-occluding particles. The mixed-cellulose-esters filter traps and quantitates radiocolloid particles irrespective of relative size. The filtrate contains free pertechnetate. Within 4 min, this method yields results that compare well with those achieved by conventional techniques. The method works equally well for large colloidal particles [( 99mTc]stannous colloid), intermediate-size particles [( 99mTc]sulfur colloid), and small-size particles [( 99mTc] antimony trisulfide colloid).

Antimony↗
PubMed1997

An automated high throughput filtration assay: application to polymerase inhibitor identification.

A high throughput filtration assay was developed and automated for screening compounds and natural product extracts using 96-well filterplates. The selection of a hydrophobic membrane and appropriate capture conditions enabled us to perform the enzymatic reaction, capture of products, vacuum filtration, and detection in a single filtration microplate, without any transfer step. The hydrophobic membrane has the advantage of preventing any loss of aqueous solution during the enzymatic reaction. The results are comparable with those obtained in a solid plate format followed by transferring the reaction mixture to a traditional hydrophilic filterplate. This assay is being used to screen for microbial RNA polymerase inhibitors as potential new drugs for treatment of emerging antibiotic-resistant bacterial and fungal infections. The filtration setup can be applied to a variety of assay systems.

Cytidine Triphosphate↗
PubMed1994

Characterization of trihalomethane (THM)-induced renal dysfunction in the rat. I: Effects of THM on glomerular filtration and renal concentrating ability.

Single non-lethal doses (3 mmol/kg) of chloroform (CHCl3), dichlorobromomethane (CHCl2Br), dibromochloromethane (CHClBr2), and bromoform (CHBr3) were administered by intraperitoneal injection to male Sprague-Dawley rats and glomerular filtration and renal concentrating ability were assessed at varied times (5-8 h, 21-24 h, and 45-58 h) following treatment. At this dose, each of the four trihalomethanes (THMs) elevated blood urea nitrogen (BUN) and reduced renal concentrating ability (as measured by H2O intake/output ratios, urinary total osmolality, and electrolyte levels). Three of the four THMs also significantly reduced glomerular filtration rate (GFR), with only CHCl3 failing to demonstrate an effect at 3 mmol/kg. In general, CHCl2Br demonstrated the greatest interference with these renal function parameters. The times of maximal THM-induced effect on BUN and glomerular filtration rate were observed to be 24 h and 21-24 h post-treatment, respectively. These data suggest that a single acute THM treatment can inhibit mammalian renal concentrating ability and glomerular filtration.

Animals↗
PubMed1981

Influence of uranyl nitrate upon tubular reabsorption and glomerular filtration in blood perfused isolated dog kidneys.

The early changes in tubular reabsorption, glomerular filtration, blood flow and sodium excretion brought about by uranyl nitrate were investigated in isolated, blood-perfused dog kidneys during water diuresis. No significant changes in urine volume were observed; the decrease in fluid reabsorption was counterbalanced quantitatively by a reduction in glomerular filtration rate; only a small diminution of renal blood flow was found. The balance between reabsorption and filtration was observed as well when angiotensin action or prostaglandin synthesis were inhibited. The intrarenal venous pressure rose, suggesting that an increase in proximal intratubular hydrostatic pressure caused the decrease in filtration. Tubular back-leak of fluid, or back-diffusion, induced by the toxin, were excluded. The presence of natriuretic compounds in the urine was confirmed.

Absorption↗
PubMed1993

Reduction of HTLV-I-infected cells in blood by leukocyte filtration.

Leukocyte filtration was performed with HTLV-I-infected blood and with blood supplemented with cultured HTLV-I-transformed cells. Reduction of infectivity upon leukocyte filtration was determined by the polymerase chain reaction (PCR) using primers indicative for the HTLV-I-pol and tax genes. Two different commercially available filters were used: a column-shaped cellulose acetate and a flat-bed polyester filter. Both filters yielded reduction of at least 3 10logs for cultured HTLV-I-infected cells. When blood from HTLV-I-infected individuals was used for filtration, the number of infected cells was reduced by 1-3 10logs. Although filtered blood as yet cannot be regarded as safe, it is concluded that leukocyte filtration of HTLV-I-infected blood potentially contributes to reducing the spread of HTLV-I by blood transfusion.

Blood↗
PubMed1975

Determination of the glomerular filtration rate by the minute diuresis at a specific gravity of 1001.

A new method is described for determination of the glomerular filtration rate, based on the fact that at an urinary specific gravity of 1001 the final urine is concentrated 6.67 times, as compared with the primary glomerular filtrate. The glomerular filtration rate is evaluated by multiplication of the minute diuresis at a specific gravity of 1001 by the factor 6.67. In this manner the chemical analysis of urine and blood is avoided. Urine with a specific gravity of 1001 is obtained by water loading much the same as in the dilution test of Volhard. For checking the accuracy of the method, comparative studies were conducted with creatinine clearance in 36 patients and with 51Cr-EDTA clearance in 33 patients. The difference in the values of the glomerular filtration rate, evaluated by the above-mentioned two methods and the new method was statistically not significant (p greater than 0.05). The method is recommended for the early detection of disturbances in the glomerular function prior to the occurrence of azotemia.

Diuresis↗
PubMed1985

Detection of anaerobic bacteria in blood cultures by lysis filtration.

An anaerobic adaptation of the lysis-filtration system for detection of anaerobic microorganisms in blood is described. The method was compared with a conventional broth bottle system in detection of anaerobic bacteremia after oral surgery. Of 43 blood samples obtained during and after surgery, 31 were positive with the lysis-filtration system and 17 were positive with the broth bottle system. Sixteen aerobic and 62 anaerobic strains were isolated with the lysis-filtration system versus 9 aerobic and 22 anaerobic strains with the broth bottles. The lysis-filtration technique was thus superior to the conventional broth bottle method in detecting anerobic bacteria.

Adult↗
PubMed1998

Seasonal changes in glomerular filtration rate in Antechinus stuartii (Marsupialia: Dasyuridae).

The small marsupial Antechinus stuartii experiences a synchronised life cycle that culminates in complete male mortality (within 3 weeks) following the 1 week mating period in mid-August (late winter). There are pronounced physiological changes in male A. stuartii over the life cycle and renal function was assessed for correlation with these changes. Glomerular filtration rate and urine and plasma electrolytes were determined in male and female A. stuartii in February, May, July and August. Females showed little change in glomerular filtration rate, except for pre-mating values in August which decreased. In contrast, glomerular filtration rate of males decreased significantly in July and August. Plasma sodium and chloride levels were higher in males than females and were higher in animals in July and August than in February and May. Plasma potassium levels dropped in both males and females in July and August. Plasma osmolality was higher in animals in February compared to animals from May and August. However, there were no significant sex or seasonal differences in urine electrolytes, although urea concentration was higher in females than males. Urine osmolality was higher in both sexes in July and August. There were no significant differences in total excretory rates of sodium, potassium or chloride between sexes or between seasons. Many of the alterations in renal function are correlated with known physiological and hormonal profiles in A. stuartii. This is the first observation of seasonal changes in glomerular filtration rate that are unrelated to dietary and water stresses.

Animals↗
PubMed1999

Streptococcal meningitis: effect of CSF filtration on inflammation and neuronal damage.

The effect of CSF filtration on inflammation and neuronal damage was studied in experimental Streptococcus pneumoniae meningitis. New Zealand white rabbits received either antibiotic therapy alone (ceftriaxone i.v., 20 mg/kg bolus, 10 mg/kg maintenance dose; n = 10) or ceftriaxone plus CSF filtration (n = 11) 12 h after intracisternal infection. Immediately after the onset of antibiotic therapy 300 microliters cisternal CSF was removed, passed through a miniaturized CSF-1 filter at a constant flow of 20 microliters/min, and then reinjected. This procedure was repeated six times at intervals of 20 min. Antibiosis plus CSF filtration caused a transient reduction in CSF bacterial titers and leukocyte counts compared with antibiosis alone (P = 0.04 and 0.02 5 h after initiation of therapy). CSF lipoteichoic acid concentrations were not reduced. The concentration of neuron-specific enolase in CSF and the density of apoptotic neurons in the dentate gyrus were almost equal 12 h after the onset of treatment. Adjuvant CSF filtration accelerated the elimination of viable bacteria from CSF in comparison to antibiotic treatment alone. Parameters of neuronal destruction, however, were not reduced.

Animals↗
PubMed2006

Evaluation of storage and filtration protocols for alpine/subalpine lake water quality samples.

Many government agencies and other organizations sample natural alpine and subalpine surface waters using varying protocols for sample storage and filtration. Simplification of protocols would be beneficial if it could be shown that sample quality is unaffected. In this study, samples collected from low ionic strength waters in alpine and subalpine lake inlets and outlets in the western United States were used to evaluate (1) effects of refrigerated storage time on the chemistry of unfiltered samples, and (2) differences in sample filtration protocols. No analytes exhibited significant changes when stored less than 48 h. Six analytes (pH, sodium, ammonium, potassium, chloride, sulfate) exhibited statistically significant (but small) changes when storage time exceeded 48 h. Two analytes (calcium, nitrate) were significantly higher when samples were field filtered than when filtered in the laboratory, but the differences were also small. For waters similar to those in this test, unfiltered refrigerated samples may be stored up to 48 h without compromising sample quality. The small differences between field and lab filtration do not justify the expense, training, and contamination risk of field filtration.

Colorado↗
PubMed1990

A comparison of the filtration, concentration, and thick smear techniques in the diagnosis of Schistosoma bovis infection in cattle and goats.

The syringe and the modified Bell filtration techniques, the cellophane faecal thick smear (Kato/Katz) and Teesdale (sandwich) smear techniques, and the formol-ether concentration technique were compared for efficiency for detection of eggs of Schistosoma bovis in faeces from cattle and goats. Both filtration techniques were highly effective as revealed by high sensitivity and mean egg counts. However, efficiency declined markedly using formalin-fixed faecal material. The efficiency of the Teesdale technique was comparable to that of the filtration techniques, whereas the efficiency of the Kato/Katz technique in goats and the formol-ether concentration technique in cattle was markedly lower. The ease of performance combined with the high sensitivity make the syringe filtration and the Teesdale techniques recommendable for field diagnosis of schistosomiasis in domestic stock.

Analysis of Variance↗
PubMed1983

Renal functional reserve in humans. Effect of protein intake on glomerular filtration rate.

This study was designed to investigate the effect of protein intake on glomerular filtration rate, and to demonstrate and evaluate the functional reserve of the kidney. Normal subjects ingesting a protein diet had a significantly higher creatinine clearance than a comparable group of normal subjects ingesting a vegetarian diet. A progressive increment in protein intake in normal volunteers resulted in a significant increase in creatinine clearance. Diurnal variations in creatinine clearance were found. These daily variations correlated well with the periods of food intake. The capacity of the kidney to increase its level of function with protein intake suggests a renal function reserve. In short-term studies, the effect of a protein load on glomerular filtration rate was evaluated. Normal subjects showed an increase in glomerular filtration rate two and a half hours after protein load to a maximal glomerular filtration rate of 171.0 +/- 7.7 ml per minute. In patients with a reduced number of nephrons, renal functional reserve may be diminished or absent.

Adult↗
PubMed1982

Cysts of Tenon's capsule following filtration surgery.

Hypertrophy of Tenon's capsule resembling a cyst and recurrence of increased intraocular pressures occurred shortly after glaucoma filtration surgery in eight patients on whom a variety of surgical techniques had been used. Preoperatively, the patients generally had secondary glaucomas with intraocular pressures exceeding 40 mm Hg. The cysts of Tenon's capsule were uniformly localized to the filtration site and were dome-shaped and hard. They were associated with intraocular pressures near the preoperative levels. Three patients were successfully treated with corticosteroids and massage. The others required surgical intervention to restore adequate filtration. Prompt recognition of a Tenon's capsule cyst and appropriate management can restore function to an otherwise failing filtration bleb.

Adult↗
PubMed1980

Liposome filtration. Dependence on transition temperature.

Liposomes formed by vortexing and passed through polycarbonate surface retention membranes showed appreciable differences in filtration behavior depending on the temperature of filtration relation relative to the liposome gel-liquid crystal transition temperature. Below transition, liposomes were filterable and size distributions could be determined; the cumulative volume distributions were log-normal. Above transition, liposomes were not filterable: smaller liposomes were formed until a limiting size was reached. These results suggest that liquid crystal liposome size distributions cannot be determined by filtration. This filtration behavior is a physical property of liposomes, related to the gel-liquid crystal transition, not previously reported. This property could be exploited as a new method for controlling liposome size distributions, but the implications for lipid membranes, including biological membranes, are general.

Filtration↗
PubMed1989

Evaluation of aluminum-yttrium filtration for intraoral radiography.

In comparison with the use of traditional aluminum filtration, a radiation dose reduction of 40% at 90 kVp and 25% at 70 kVp was found with the use of aluminum-yttrium (Al-Y) filtration for intraoral bitewing and periapical radiographs. An increased exposure time, and consequent greater tube loading, was necessary to maintain film density. Extended gray-scales (i.e., reduced radiographic contrast) occurred at both energy levels tested with the use of Al-Y filtration. Subjective evaluation of image quality in terms of clarity, resolution, and contrast was carried out independently by nine periodontologists. Despite some interoperator variance, there was a preponderant preference for traditional aluminum filtration.

Aluminum↗
PubMed1995

A simple method for measuring glomerular filtration rate in dogs.

A technique for measuring glomerular filtration rate (by six-sample plasma clearance) and extracellular fluid volume is described. The results obtained for glomerular filtration rat per extracellular fluid volume with a three blood sample technique are also presented. Concurrently with the blood sample techniques measuring plasma clearance, glomerular filtration rate per extracellular fluid volume was also measured using an external radiation detector and no blood samples. The validity of expressing glomerular filtration rate per extracellular fluid volume (rather than per body weight or surface area) and the clinical utility of the results obtained with the external radiation detector are discussed.

Animals↗
PubMed1987

Correlation between chemical stimulation and filtration flow resistance in human platelet aggregates.

Human platelet-rich plasma (PRP) was aggregated with ADP to produce varying degrees of reversibility and platelet release, and then the chemical stimulation (as evidenced by optical transmittance) was compared with the flow resistance of physiologically-significant microaggregates, determined by constant-pressure filtration. The aggregate flow resistance was attributed to "weak" aggregates (which occluded the micropore filter at 20 mm Hg but which passed through the filter at 80 mm Hg) and "strong" aggregates (which occluded the filter at 80 mm Hg). As the ADP concentration was increased from 1 microM to 10 microM, the flow resistance of both the "weak" and "strong" aggregates generally increased, as did the maximum transmittance. No consistent trend was seen as the time after ADP addition increased from 5 to 30 minutes. Pretreatment of the PRP with epinephrine increased the maximum transmittance during ADP aggregation, produced less-reversible aggregates (less subject to deaggregation by PGE1), and increased the aggregate flow resistance over the range of filtration pressures tested. The addition of PGE1 to the aggregated sample before filtration nearly eliminated the flow resistance of the aggregates at all filtration pressures tested and partially reversed the optically-apparent aggregation. Pretreatment of PRP with PGE1 before epinephrine or ADP addition inhibited both the optically-detected aggregation and the development of flow resistance. The physical (hydrodynamic) strength of platelet aggregates is apparently related to the chemical stimulation of the release reaction and to aggregation irreversibility, possibly through the mediation of adenylate cyclase and cyclic AMP.

Adenosine Diphosphate↗