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PubMed1988

Measurement of glomerular filtration rate by impulse synthesis: clinical validation and optimization.

Impulse synthesis is a technique which relies upon the logic of continuous infusion but extracts the clearance value from single-injection data by shifting and adding them until an asymptotic value is attained. This study has been aimed at validating and optimizing clinically the measurement of glomerular filtration rate by impulse synthesis. A single intravenous injection of 51Cr-EDTA has been made in 32 patients and plasma activity monitored over the next 6 h. Glomerular filtration rate computed by a single-exponential fit method (GFR-SEF) has been shown to be significantly (p less than 0.001) overestimated when compared with the glomerular filtration rate obtained by the impulse synthesis technique (GFR-IS) in spite of an excellent (r = 0.989) linear correlation between the two sets of data. On the other hand, the comparison between GFR-IS and 24-h creatinine clearance has not shown any significant difference. Moreover, we have found that in patients with severe renal failure GFR-IS is overestimated when the sampling time span is shortened to 3 h. On the other hand, GFR-IS is slightly underestimated in patients with severe renal failure when the convolution time interval is increased over a few minutes.

Adult↗
PubMed1988

[Evaluation of cascade filtration on a test sample].

Double filtration or filtration in series can be consider as an effective means of removing proteins such as IgG, IgM, immune complexes, lipoproteins from plasma. In this study, we evaluated, using a biological and technical protocol: Kuraray (2A and 4A) and Dideco (Albusave) filters. Results were good by analysis of the sieving coefficient, but the method had 2 inconveniences: problem of slogging of the columns after filtering 2 liters and too high a reject coefficient of albumin. No effective solutions exist to avoid these two problems. Nevertheless, the filtration in series technic seems to be a good method for removing cholesterol and we have undertaken new studies to improve this system.

Blood Component Removal↗
PubMed1987

Effects of Nva2-cyclosporine on glomerular filtration rate and renal blood flow in the rat.

The effects of Nva2-cyclosporine on glomerular filtration and renal blood flow in rats were studied and compared with those of cyclosporine. An infusion of Nva2-cyclosporine (20 mg/kg) caused a 53% fall in glomerular filtration rate (1.0 +/- 0.08 to 0.47 +/- 0.09; P less than 0.001) and renal plasma flow (3.2 +/- 0.4 to 1.6 +/- 0.4; P less than 0.005). Nva2-cyclosporine when infused in a dose of 10 mg/kg caused a nearly identical fall in inulin clearance and renal plasma flow. By comparison an infusion of cyclosporine (20 mg/kg) caused a 50% decrease in inulin clearance and a fall in renal plasma flow from 2.6 +/- 0.3 to 0.9 +/- 0.3. Nva2-cyclosporine or cyclosporine was given chronically in a dose of 20 mg/kg intraperitoneally for seven days. Cyclosporine produced a 27% fall in creatinine clearance, whereas Nva2-cyclosporine produced a 19% decrease in creatinine clearance (NS). These studies suggest that Nva2-cyclosporine has adverse effects on renal blood flow and glomerular filtration rate similar to those seen with cyclosporine.

Animals↗
PubMed1986

Evaluation of 99mTc-diethylenetriaminepentaacetic acid nuclear imaging for quantitative determination of the glomerular filtration rate of dogs.

The suitability of 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) as an agent to assess glomerular filtration rate (GFR) in dogs was evaluated. Glomerular filtration rates of 12 healthy dogs were determined on the basis of creatinine and/or inulin clearance. Glomerular filtration rates also were determined in 7 dogs after induction of acute renal failure by administration of amphotericin B. The healthy dogs and the amphotericin B-treated dogs were given 99mTc-DTPA (1 to 2 mCi) IV. The percentage of the 99mTc-DTPA dose in the kidneys (percentage dose) was determined, with background activity subtracted from total activity at 15-s intervals 0 to 6 minutes after 99mTc-DTPA infusion. Linear regression analyses (LRA) were performed to determine whether the percentage dose at various time intervals after injection correlated with GFR calculated on the basis of creatinine and inulin clearance data. One to 3 minutes after 99mTc-DTPA administration appeared to be the best period for analysis of the data. The percentage dose of 99mTc-DTPA (corrected for kidney depth differences) was determined and LRA against GFR were performed. The percentage dose correlated better with inulin clearance (r = 0.94) than with endogenous creatinine clearance (r = 0.83). Only inulin clearance correlations improved with kidney depth correction. The LRA was used to derive an equation that could be used to calculate GFR on the basis of the percentage dose. The equation derived from inulin regression was: GFR (milliliter/minute/kilogram of body weight) = 0.194 (depth-corrected percentage dose)--0.37; the equation derived from the creatinine regression was: GFR (milliliter/minute/kilogram) = 0.171 (depth-corrected percentage dose)-0.15.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1986

Effect of experimental diabetes on glomerular filtration rate and glomerular prostanoid production in the rat.

Glomerular hyperfiltration is an early functional renal lesion seen both in experimental and human diabetes mellitus. This increase in the glomerular filtration rate has been thought to be mediated, in part, by changes in vasoregulatory hormones such as the prostanoids. The present study was designed to measure glomerular prostanoid production in rats with experimental diabetes to determine whether the biochemical changes in prostanoid production could be consistent with the hemodynamic alterations noted. Sprague-Dawley rats were studied either 7 or 28 days after intravenous streptozotocin administration (60 mg/kg). Measurements of the glomerular filtration rate were performed in two groups of diabetic animals 28 days after streptozotocin administration: one group with intact prostanoid production, the other having received a cyclooxygenase inhibitor for the 4-week period. Similar studies were performed in nondiabetic control rats. Measurements of glomerular prostanoid production were performed in control and diabetic animals 7 days after streptozotocin administration. The results of these studies indicate that experimental diabetes mellitus is associated with an increase in the glomerular filtration rate and that this increase can be blocked by the administration of a cyclooxygenase inhibitor. In addition, the determination of levels of various glomerular prostanoids indicated an increased production of prostacyclin and a decreased production of thromboxane during this period of hyperfiltration. Thus, these data support the premise that altered prostanoid biosynthesis may be one of the biochemical mediators of the hyperfiltration seen in early experimental diabetes mellitus.

Animals↗
PubMed1979

[Compared study of micro-aggregates filters (output, filtration pressure and study of the deposit with scanning electron microscopy) (author's transl)].

Special filters for the elimination of cellular aggregates were conceived especially to prevent pulmonary complications in patients shocked particularly after massive transfusions as well as to prevent cerebral complications after extra-corporeal circulation. The performances and the conditions of use of these filters (perfusion output, change of the filter) were considered. Four filters were carefully studied: the Fenwal filter, the Swank filter, the Biotest filter and the intersep Johnson and Johnson filter. The following studies were carried out for each filter: the perfusion output (of three bottles filtered one after another with or without pressure); the filtration pressure (Swank technique) of the whole blood up-and-down filter; the viscosity and various hematologic parameters (NF, hemoglobin and gobular ATP); finally, the deposit was studied morphologically with scanning electron microscopy. It appeared that a good capacity of aggregates elimination (decrease of the filtration pressure of 95%) was often linked to a feeble output and the necessity of replacing the filter. The efficacy of the Fenwal filter, the Swank filter, the Biotest filter and the intersept filter was practically the same, but the Intersept filter provided the best output with an equal filtration capacity. The other parameters remained about the same. The deposits included fibrinogen, deformed red blood corpuscules (echinocytes), leucocytes and platelets.

Blood Transfusion↗
PubMed1985

Filtration fraction: an index of renal disease activity in patients with systemic lupus erythematosus.

Renal plasma flow (RPF) and glomerular filtration rate (GFR) were estimated by 125I hippuran and 51Cr EDTA clearances using a single shot technique on two occasions at one-year intervals in 22 patients fulfilling the ARA criteria for systemic lupus erythematosus (SLE). All these patients had histologically proven renal disease. Filtration fraction was a better parameter than proteinuria, urinary sediment or GFR for recognising diffuse proliferative glomerulonephritis with a sensitivity of 61 per cent and a specificity of 88 per cent. After one year all the patients with an initially low filtration fraction (FF) had significantly changed their GFR, which demonstrates that this parameter indicates the presence of an active renal lesion.

Glomerular Filtration Rate↗
PubMed1985

Current status of membrane plasma separation and plasma filtration techniques.

Blood and plasma processing by membranes was introduced into clinical medicine in 1979. In the meantime, membrane plasma separation (plasmapheresis) has become very satisfactory and is now a routine therapeutic procedure in many apheresis centers. Plasma fractionation by membranes (plasma filtration or cascade filtration) for unselective removal of high molecular weight pathogens from the separated plasma is technically possible but its routine clinical application is still limited to a few diseases with at least IgM-sized target proteins. The separation of IgG from albumin needed to treat many autoimmune diseases requires further development of both the membranes and the filtration technology.

Filtration↗
PubMed1985

Evaluation of two new filtration systems--Fenwal PS400 and Organon Teknika Curesis--and comparison of results with two centrifugation systems--IBM model 2997 and Haemonetics V50.

Two new filtration systems (Fenwal CPS 10TM - PS 400 and Organon Teknika Curesis - M82) were evaluated and compared with two centrifugal cell separators (IBM 2997 and Haemonetics V50). 11 patients with auto immune diseases and dermatological diseases underwent 230 consecutive plasma exchanges. For the filtration systems, the average whole blood rate was 50 ml/min and the plasma separation rate was about 21 ml/min for a transmembrane pressure about 70 mmHg. The pre/post percent reduction and sieving coefficient were calculated for some plasma and blood components. A variety of laboratory studies was monitored to assess the efficacy of plasma separators, their biocompatibility and some yields. These results show that the 2 filters appear safe and efficacious but their modules are too simple and do not offer a great security (no transmembrane pressure control or no extracorporeal fluid balance). For a blood banker, IBM 2997 seems more interesting if we take in account its characteristics during plasma exchanges and the possibility which is offered to carry out cytapheresis procedures. But for a thrombopenic patient the filtration systems keep their advantages.

Autoimmune Diseases↗
PubMed1977

A simple method for the estimation of glomerular filtration rate.

A simple method is presented for indirect estimation of the glomerular filtration rate from two venous blood samples, drawn after a single injection of a small dose of [125I]sodium iothalamate (10 muCi). The method does not require exact dosage, as the first sample, taken a few minutes (t = 5 min) after injection, is used to normalize the value of the second sample, which should be taken in between 2-4 h after injection. The glomerular filtration rate, as measured by standard inulin clearance, may then be predicted from the logarithm of the normalized value and linear regression formulas with a standard error of estimate of the order 1-2 ml/min/1.73 m2. The slope-intercept method for direct estimation of glomerular filtration rate is also evaluated and found to significantly underestimate standard inulin clearance. The normalized 'single-point' method is concluded to be superior to the slope-intercept method and more sophisticated methods using curve fitting technique, with regard to predictive force and clinical applicability.

Adult↗
PubMed1984

[Beta 2 microglobulin. Index of glomerular filtration in children].

121 assays for plasma Beta 2 microglobulin (B2M) levels were carried out with an immuno-enzymatic technique in 94 children whose ages ranged from 13 months to 18 years and whose renal functions showed various levels of renal impairment. In the 37 children with normal glomerular filtration rate, plasma B2M level was 1.58 +/- 0.48 mg/l (mean +/- 1 SD) and no significant differences were found according to sex, ages or heights. In the 29 children with glomerular filtration rate (GFR) ranging from 20 to 100 ml/min/1.73 m2, there was a significant correlation between B2M and the inulin clearance, plasma creatinine level and creatinine clearance (p less than 0.001). In 28 patients presenting with terminal renal failure, plasma B2M levels were significantly higher in children undergoing hemodialysis than in those under chronic peritoneal dialysis. These results indicate that B2M levels are as good an index of glomerular filtration rate as serum creatinine whereas its assay uses a long and difficult technique.

Adolescent↗
PubMed1983

The effect of filtration on the loss of abnormal cervical cells in specimen preparation for automated cytology.

The UCLA monolayer procedure is used to produce a preparation of cervical epithelial cells for automated cytology. We investigated the nylon mesh filtration step of the procedure to determine if it altered the proportion of abnormal epithelial cells in the specimen. The proportion of such cells was found to be significantly lower (P less than 0.05) in the final specimen retained by a 10 micron nylon mesh filter than in the filtrate, which has been routinely discarded in our studies. The filtrate specimen is contaminated by large numbers of polymorphonuclear leukocytes, however, making it unusable for automated cytology at present. The implications of our findings for the cost effectiveness of classifier performance are considered, and the implications of the results for further improvements in specimen preparation are discussed.

Cell Separation↗
PubMed1981

The monitoring of antigen levels during inactivated poliovirus vaccine production: evaluation of filtration techniques.

The use of ELISA to estimate poliovirus antigen concentration has permitted an evaluation of the methodology used in vaccine production and allowed exploration of less wasteful filtration-techniques. The replacement of Seitz-EKS-1B filtration with either Seitz-Supra-EKS or Pall-filtration in the preparation of the vaccine could make a large saving in the total antigen yield, but the results in the safety test excluded their possible use in our process as it stands at the moment.

Animals↗
PubMed1982

[The value of the x-ray spectrum with regard to x-ray filtration (author's transl)].

After some preliminary remarks on the production and spectral composition of X-Rays it is demonstrated, how the total filtration of the X-Rays including the filtration in the anode can be found from the X-Ray Bremsspektrum. The curves for determining this filtration include filters up to 50 mm AI-Equivalent for 40 to 150 kV constant direct voltage.

Filtration↗
PubMed1982

Two-dimensional gel electrophoresis method for investigation of human plasma proteins: detection of subtle changes during filtration leukapheresis.

Special problems are associated with analysis of human plasma proteins by standard "high-resolution" two-dimensional gel electrophoresis methods in which isoelectric focusing is followed by electrophoresis in sodium dodecyl sulfate/polyacrylamide gels (SDS-PAGE). Individual plasma proteins are often separated into overlapping groups of multiple spots, and identification of individual spots is further confounded by genetic variation. Analytical recovery of components of high molecular mass is also low or variable. These problems may be reduced or overcome by use of a "low-resolution" method consisting of electrophoresis of native proteins at pH 8.6 in an agarose gel followed by SDS-PAGE without added reducing agent. About 60 proteins can be resolved, most as single spots. About 25 of these proteins have been "mapped," and tentatively identified. We have examined 119 plasma samples taken from six donors who were undergoing filtration leukapheresis and 10 donors who were undergoing centrifugation leukapheresis or plateletpheresis. In all cases, passage of blood through a nylon filter induced a significant increase in a doublet of spots tentatively identified as complement component C3c. This was detected in the effluent from the filter throughout the first 30 min of filtration, and to a lesser extent in the venous blood. These spots were not induced by the centrifugation procedures. One filtration donor also showed increased acute-phase proteins 24 h after the procedure.

Blood Proteins↗
PubMedDate not supplied

[Use of coherent optical spatial filtration for improving the quality of x-ray images].

The article deals with the problem of using the method of optical spatial filtration, applied at present in radiodiagnosis for solving a number of problems connected with image processing in order to reduce the influence of disturbances, to compensate the transfer functions, etc. The process of the formation of roentgen shadow projection is described by integral equations. In this way the possibility for correcting a posteriori the transfer characteristics of the processes of the formation and fixation of roentgenograms has been revealed, and the maximum dimensions of objects capable of being successfully processed by spatial filtration, as well as the necessary filtering functions of the correction filter, have been determined. The problem of measuring the transfer characteristics of radiodiagnostic systems is discussed, and the method of measuring the complex transfer function, suitable for the spatial variant system, is proposed. On the basis of a short review of publications on this problem, and taking into consideration the above analysis, the trends of using the methods of optical filtration are determined. The authors believe that these methods used within the determined trends may improve the quality of roentgen images and, in the end, the diagnostic value of roentgenograms.

Filtration↗
PubMed1981

Simple, accurate method for clinical estimation of glomerular filtration rate in the dog.

Simultaneous [14C]inulin and exogenous creatinine clearance procedures were performed on 10 healthy adult dogs of both sexes after constant IV infusions of inulin and a single subcutaneous injection of creatinine. For 30 clearance procedures determined for 10 dogs, the creatinine/inulin (C/I) clearance ratio was 1.03 +/- 0.01, and the results of the 2 tests were highly correlated (r = 0.91). Simultaneous [14C]inulin and endogenous creatinine clearance procedures were performed in the same 10 dogs. For 30 clearance procedures in these dogs, the C/I clearance ratio was 0.70 +/- 0.06 and the 2 tests were less highly correlated (r = 0.79). Fifteen clearance procedures of the same design were conducted on 5 dogs with azotemia induced by surgical reduction of renal mass. In these dogs, the exogenous C/I clearance ratio was 1.09 +/- 0.12, and the endogenous C/I clearance ratio was 0.89 +/- 0.07. It was concluded that the single injection method of exogenous creatinine clearance was a valid method for clinical measurement of glomerular filtration rate in the female dog and would closely approximate glomerular filtration rate in male dogs without azotemia. At normal or near normal plasma creatinine levels, the endogenous creatinine clearance procedure gave erroneously low values for glomerular filtration rate when the common methods of creatinine analysis were used.

Animals↗
PubMed1980

Blood pressure, plasma volume, extracellular volume and glomerular filtration rate during treatment with labetalol in essential hypertension.

In 17 patients with essential hypertension administration of labetalol alone resulted in a significant reduction in supine systolic and diastolic blood pressure of 14% and 17%, respectively. Seven patients attained a diastolic pressure less than equal to 95 mmHg. A significant postural fall in systolic blood pressure was recorded, but no symptomatic orthostatic hypotension occurred. Pulse rate decreased significantly by 8%. Side effects were few causing only two withdrawals. In twelve patients plasma volume (125I-albumin), extracellular volume (82Br-distribution space) and glomerular filtration rate (51Cr-EDTA clearance) were measured during a placebo period and on labetalol alone given for an average of 3 months and 3 weeks. Plasma volume and extracellular volume increased insignificantly by 5% and 4%, respectively. Glomerular filtration rate was unchanged. In conclusion, this study showed that labetalol given alone to patients with mild or moderate essential hypertension resulted in significant, persistent and clinically relevant reductions in blood pressure without concomitant fluid retention or influence on glomerular filtration rate.

Adult↗