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PubMed1997

Lack of renal effects of fish oil administration in patients with advanced cirrhosis and impaired glomerular filtration.

The treatment of renal failure in cirrhotic patients with ascites remains unsatisfactory. Recent studies have shown that the dietary supplementation with fish oil improves the renal function of normal subjects, as well as that of patients with renal failure of different etiologies. We have investigated the renal effects of a daily supplementation for 1 month of 12 g fish oil (27% C20:5 n-3 eicosapentanoic acid [EPA], and 23% C22:6 n-3 docosahexanoic acid [DHA]) in a prospective study of cirrhotic patients with ascites, nine with normal renal function (group 1) and eight with renal failure (glomerular filtration rate [GFR] < 60 mL/min, group 2). Compliance with the dietary regimen was confirmed by fatty acid chromatography that showed increased plasma concentration of EPA (from 1.5 +/- 0.7% to 3.7 +/- 0.8%, P = .024, in group 1; and from 0.53 +/- 0.3% to 2.9 +/- 0.8%, P = .03, in group 2) and of DHA (from 2.1 +/- 0.4% to 3.4 +/- 0.3%, P = .008, in group 1; and from 1.45 +/- 0.5% to 3.8 +/- 0.4%, P = .05, in group 2). At the end of the study, in patients from group 1, the glomerular filtration rate increased by 19% (from 94 +/- 8 to 113 +/- 13 mL/min, P = .039), and the urine flow increased by 39% (from 0.85 +/- 0.14 to 1.12 +/- 0.2 mL/min, P = .039), while no changes occurred in the renal function of patients from group 2. No changes were observed in the urinary excretion of prostaglandin (PG) E2 or of 6-keto prostaglandin-1-alpha (6-K-PGF1-alpha) nor in plasma renin activity (PRA) or the plasma concentration of aldosterone (PA) or antidiuretic hormone (ADH) in both groups. As far as undesirable effects of fish oils were considered, the mean arterial pressure (MAP) decreased in both groups (group 1: from 88.6 +/- 2 to 85.3 +/- 2 mm Hg, P = .015; group 2: from 88.2 +/- 3 to 82.8 +/- 3 mm Hg, P = .05), and bleeding time displayed a significant increase when patients were considered collectively (from 744 +/- 89 to 872 +/- 106 seconds, P = .0068). In conclusion, the administration of fish oil for 1 month was unable to improve renal function in cirrhotic patients with ascites and renal failure. The occurrence of undesirable effects, such as the reduction of arterial pressure and the prolongation of bleeding time, argues against the use of fish oils in these patients.

Ascites↗
PubMed1996

Lack of diurnal variation in glomerular filtration rates in the elderly.

The present study was undertaken to examine the effect of age on diurnal variation in glomerular filtration rate (GFR). The GFR, as estimated by creatinine clearance (Clcr), was determined during a 24-hour period in 10 younger (mean +/- SD age 42 +/- 9 years) and 10 older (mean age 75 +/- 4 years) patients with hypertension. Significant diurnal variations in Clcr were observed in the younger patients, with a peak during the day and trough during the night. Such were not observed in the older patients, however. These results suggest that diurnal variation in GFR is affected by age. Chronopharmacologic profiles of drugs, which are mainly excreted in urine by glomerular filtration, might be altered in these patients.

Adult↗
PubMed1995

Effectiveness of cascade filtration plasmapheresis in two patients affected by familial hypercholesterolemia.

Hypercholesterolemia has been recognised as a primary risk factor for coronary heart disease. Reduction of plasma levels of total and LDL cholesterol has been shown to decrease coronary atherosclerosis. Plasmapheresis represents an useful non-pharmacological tool to treat severe hypercholesterolemias. We have evaluated the effectiveness of a system of plasmapheresis using a cascade filtration method in two young male subjects (aged 16 and 26 years) with homozygous familial hypercholesterolemia. Both showed severe coronary atherosclerosis as determined by angiography. Procedures were performed at intervals of 7 days in each case. We observed a mean reduction of plasma levels of total cholesterol of 59.5% (range 31.0-75.5%); LDL-cholesterol, 61.6% (range 32.6-77.1%); triglycerides, 48.1%; HDL-cholesterol, 31.1%; apo A-I, 30.8%; and apo B, 57.6%. We also noted a reduction of other parameters, such as fibrinogen (49.9%) and Lp(a) (59.9%). At the end of each procedure about 8 g of cholesterol was removed from the total body pool. A decrease of total proteins (26.9%) and albumin (19.6%) was also observed, but this was completely restored before the next apheresis (1 week). These data show the effectiveness of the removal of LDL in a cascade filtration system, which obtains results not very different from other more selective methods. The lack of selectivity is not much of a problem, since it also reduces other risk factors such as Lp(a) and fibrinogen.

Adolescent↗
PubMed2004

Glomerular filtration rate: assessment with dynamic contrast-enhanced MRI and a cortical-compartment model in the rabbit kidney.

PURPOSE: To describe the use of MRI and a cortical-compartment model to measure the glomerular filtration rate (GFR), and compare the results with those obtained with the Patlak-Rutland model. MATERIALS AND METHODS: Dynamic MRI of rabbit kidneys was performed during and after injection of gadoterate dimeglumine. The enhancement curves in the aorta and the kidney were analyzed with the cortical-compartment and Patlak-Rutland models to assess the GFR. RESULTS: A substantial correlation was observed between the GFR measured with MRI using the cortical-compartment model and the plasma clearance of 51Cr-EDTA (r=0.821, P=0.004). No significant correlation was observed between the 51Cr-EDTA clearance (r=0.628, P=0.052) and the GFR obtained with the Patlak-Rutland model in regions of interest (ROIs) encompassing the renal cortex and medulla. A Bland and Altman analysis showed that GFR(cortical) (compartment) agreed better with the 51Cr-EDTA clearance compared to GFR(Patlak) when ROIs were limited to the cortex. However, the GFR values obtained by MRI were lower than the plasma clearance of 51Cr-EDTA. CONCLUSION: MRI with a cortical-compartment model provides more accurate assessments of glomerular filtration than the Patlak-Rutland model.

Animals↗
PubMed1982

Comparison of centrifugation and filtration assays of ligand binding: do multiple GABA receptive sites exist?

Filtration and microcentrifugation procedures for the separation of bound and free ligand are compared for the assay of GABA receptors. The 3H-GABA and 3H-muscimol are employed as ligands in saturation analyses of SPM and JC preparations. A direct comparison of the two methods, applied to two membrane preparations and two ligands, reveals that nonspecific binding is consistently higher with the microcentrifugation procedure. Analysis of the binding data yields essentially the same constants in either case; however, the filtration assay provides a better estimate in all cases.

Animals↗
PubMed1988

Contrast media and glomerular filtration: dose dependence of clearance for three agents.

Determination of plasma clearance of contrast agents has been advocated as a means to assess glomerular filtration rate. To evaluate the feasibility of different agents for this purpose, we have compared, in healthy volunteers, the dose dependence of plasma clearance for three contrast media (iohexol, a nonionic agent, and iothalamate and metrizoate, which are ionic substances), with special emphasis on the lower dose range (2-20 mL corresponding to 0.9-12.9 g, depending on dose and agent). Iohexol and iothalamate were cleared at constant rates, irrespective of given dose, whereas metrizoate clearance increased significantly at lower doses. In general, the clearances or iothalamate and metrizoate were, respectively, moderately and markedly higher than that of iohexol. The clearance of different doses of metrizoate (2 mL versus a radiographic dose of 40 mL or more) was also compared with the clearance of [51Cr]EDTA in two groups of patients with reduced renal function. When compared with [51Cr]EDTA in patients with renal dysfunction, metrizoate was cleared significantly faster after a 2-mL dose, whereas clearances were identical when the metrizoate dose was 40 mL or more. These findings indicate that tubular secretion plays an active role in the elimination of metrizoate. The pharmacokinetic properties of iohexol, in combination with its low toxicity, make it a suitable agent for determination of glomerular filtration rate in clinical practice.

Adult↗
PubMed2005

Ultrasonic extraction followed by a novel filtration and clean-up device for screening of some polyphenols in tobaccos.

A simple and efficient HPLC method using a diode array detector (DAD) was developed for simultaneous determination of six polyphenols in tobaccos. Ultrasonic extraction was employed at 25 degrees C to extract the polyphenols present in tobaccos into anhydrous methanol. A novel filtration device linked to a clean-up cartridge was designed for simultaneous extract filtration and clean-up. Optimized HPLC-DAD analysis, with multi-wavelength detection, was used for determination of the polyphenols. Because the content of some of the polyphenols is too low to be quantified directly, a concentration step was necessary. Anhydrous methanol was employed for extraction of the polyphenols because of its high extraction efficiency and its low boiling point in the concentration step. Using the proposed method, six polyphenols were quantified in tobaccos (Nicotina tobaccum L.).

Chromatography↗
PubMed1995

A filtration method for plasmid isolation using microtiter filter plates.

A method for the simultaneous isolation of plasmid DNA from as many as 96 Escherichia coli clones in less than 2 h is described. It is based on a modified version of the alkaline lysis procedure originally described by Birnboim and Doly (Nucleic Acids Res. 7, 1513-1523, 1979). The handling of DNA samples is facilitated by the use of microtiter plates with membrane filter bottoms. All centrifugation steps are replaced by filtrations ("the filtration method"). The yield of plasmid DNA from 0.35 ml of an overnight culture is sufficient for restriction analysis of the plasmid clones. Up to 400 nucleotides' readable sequences could be obtained in cycle sequencing reactions with an unmodified sequencing protocol on an automated ABI sequencer.

Bacteriological Techniques↗
PubMed1995

Physiological time and the measurement of glomerular filtration rate.

Diverse physiological timescales in different animals can have an important influence on the measurement of biological variables. In vertebrates, the absolute and relative rates of glomerular filtration span several orders of magnitude. These differences have important implications for the logistics of measurement protocols in different species. A simple model is used to examine the importance of physiological time to the measurement of glomerular filtration rate.

Animals↗
PubMed1999

Purification of human chorionic gonadotrophin from urine by membrane filtration affinity chromatography with a positively charged membrane.

UNLABELLED: A new method of affinity chromatography, termed membrane filtration affinity chromatography (MFAC), has been developed and applied to purify HCG from urine. By filtrating urine through ZBM (HCG in urine would bind to the antibody on ZBM) and by dissociating the HCG from the antibody on ZBM in purified form, we developed the MFAC and purified HCG from urine of pregnant women by MFAC. The purified HCG showed a single band in polyacrylamide gel electrophoresis. ZBM (1 cm(2)) could harvest 90.3 microg HCG, which showed immunoactivity of 8554 IU/mg. The rate of recovery was 87%. CONCLUSION: MFAC with ZBM is an effective method, which is much easier and cheaper than conventional affinity chromatography for purification of proteins from solution, especially from highly diluted solution.

Chorionic Gonadotropin↗
PubMed2003

The influence of L-tryptophan peroral load on glomerular filtration rate in chronic glomerulonephritis and chronic renal failure.

The results of our clinical observations of 102 patients with chronic glomerulonephritis with normal renal function and 10 patients with chronic renal failure, as well as 10 healthy individuals allow us to conclude that in patients with high proteinuria and impaired renal function the serum concentration of tryptophan is decreased, both before and after peroral L-tryptophan load. We have found a positive correlation between serum concentration of albumin and tryptophan in patients with normal kidney function, and negative correlations between serum concentration of albumin and intensity of proteinuria, as well as between serum concentration of tryptophan and proteinuria. Our studies have shown that L-tryptophan peroral load increases the glomerular filtration rate in healthy individuals, in patients with membronous proliferative glomerulonephritis with proteinuria 2 g/24 h and mesangioproliferative glomerulonephritis with proteinuria < 2 g/24 h. In patients with high proteinuria (> 2 g/24h) and decreased renal function L-tryptophan load does not influence the glomerular filtration rate.

Administration, Oral↗
PubMed2006

Types of filtration.

There are a multitude of filter designs and mechanisms utilized within the biopharmaceutical industry. Prefilters are commonly pleated or wound filter fleeces manufactured from melt-blown random fiber matrices. These filters are used to remove a high contaminant content within the fluid. Prefilters have a large band of retention ratings and can be optimized to all necessary applications. The most common application for prefilters is to protect membrane filters, which are tighter and more selective than prefilters. Membrane filters are used to polish or sterilize fluids. These filters need to be integrity testable to assess whether or not they meet the performance criteria. Cross-flow filtration can be utilized with micro- or ultrafiltration membranes. The fluid sweeps over the membrane layer and therefore keeps it unblocked. This mode of filtration also allows diafiltration or concentration of fluid streams. Nanofilters are commonly used as viral removal filters. The most common retention rating of these filters is 20 or 50 nm.

Biopharmaceutics↗
PubMed1993

Characteristics of cross-flow filtration of pullulan broth.

Cross-flow filtration of culture broth from Aureobasidium pullulans, which elaborates pullulan, was done with a thin channel-type module and microfiltration membranes made of different materials and with different pore sizes. Various factors affecting the results of the filtration were studied. The specific resistance of the microbial cake was found to be higher than that of bakers' yeast, the cells of which are about the same size as an A. pullulans cell, and resistance increased with cultivation time. The flux and transmission of pullulan through the membrane decreased with cultivation time as the specific resistance increased. The flux and transmission of pullulan depended on the structure and pore size of the membrane and also on the pH of the broth. With a polysulphone membrane with a nominal pore size of 2.0 microns, transmission was nearly 100% with negligible leakage of cells and the flux was high when the pH of the broth was adjusted to 2.0.

Culture Media↗
PubMed1993

Nephrotoxicity of cyclosporine in humans: effect of cyclosporine on glomerular filtration and proximal tubular reabsorption.

The chronic nephrotoxic effects of cyclosporine (CsA) include proximal tubular atrophy and vacuolization. This study investigated the effect of CsA on renal hemodynamics and segmental electrolyte transport in CsA-treated patients. The clearance of inulin (CIn) and PAH para-amino-hippuric acid (CPAH) was determined; proximal tubular function was studied using a lithium clearance method and calculating tubular phosphate reabsorption per milliliter of glomerular filtrate (TP/CIn). Twenty patients without renal disease were investigated: ten treated with CsA because of nonrenal grafting (group 1) and ten healthy volunteers (group 2). The results obtained were compared with those from 20 renal allograft recipients, of whom ten were treated with CsA and methylprednisolone (group 3) and ten with azathioprine and methylprednisolone (group 4). CIn and CPAH were significantly impaired in patients treated with CsA. No significant impairment of lithium clearance as induced by CsA was observed. The fractional excretion of lithium was slightly increased in patients treated with CsA compared to their respective controls. TP/CIn was lower in graft recipients compared to controls; no impairment of phosphate reabsorption as induced by CsA was found. The fractional tubular excretion of lithium was slightly increased compared to controls, rising evidence that proximal tubular reabsorption of lithium was decreased. Tubular reabsorption of phosphate was not impaired. The decrease in glomerular filtration and renal perfusion during chronic treatment with CsA was accompanied by a reduced proximal reabsorptive capacity, as was shown by lithium clearance. Our data do not support the hypothesis that functional parameters of the proximal tubular system can be used as indicators of CsA-induced nephrotoxicity.

Absorption↗
PubMed1981

A prospective study of glomerular filtration rate and arterial blood pressure in insulin-dependent diabetics with diabetic nephropathy.

Glomerular filtration rate (GFR, single bolus 51Cr-EDTA technique), serum creatinine, proteinuria and arterial blood pressure have been measured prospectively in 14 young onset insulin-dependent diabetics selected by of persistent proteinuria (greater than 0.5 g/day) secondary to diabetic nephropathy. Twelve of the 14 patients had normal serum creatinine levels. None of the patients received antihypertensive treatment. During the mean observation period of 26 months (range 23 to 33 months) GFR decreased from 107 to 87 ml/min/1.73 m2 (p less than 0.001), serum creatinine remained unchanged: 107 and 112/mumol/l (NS), proteinuria increased from 1.8 to 3.3 g/day (p less than 0.001) and arterial blood pressure rose from 132/88 to 153/101 mmHg (p less than 0.001). Glomerular filtration rate decreased linearly with time (slope = -0.75, r = 0.99, p less than 0.001) by a mean of 0.75 ml/min/month (range 0.1 to 1.5 ml/min/month). The decrease in GFR did not correlate wih sex, age at onset, duration of diabetes, arterial blood pressure, proteinuria, insulin requirement, postprandial blood glucose or the initial GFR in each individual was constant, but varied considerably between patients. Increase in arterial blood pressure to a hypertensive level is an early feature of diabetic nephropathy in young insulin-dependent diabetics.

Adult↗
PubMed1982

Dysfunction of tubular phosphate reabsorption related to glomerular filtration and blood glucose control in diabetic children.

The renal handling of inorganic phosphate was studied by measuring the urinary excretion rate of phosphate (UPO4V), phosphate-(Cr51) EDTA clearance ratio (CPO4/GFR) and maximal tubular reabsorption of phosphate per litre glomerular filtrate (TmPO4/GFR) during fasting in 26 ambulatory Type 1 (insulin-dependent) diabetic children without clinical signs of microangiopathy (age: 7-14 years; duration of disease: 3-14 years). Similar measurements were made in 28 healthy schoolchildren (age: 8-14 years). UPO4 V and CPO4/GFR were significantly enhanced in the diabetic children (p less than 0.001) and correlated with the degree of hyperglycaemia (p less than 0.005). TmPO4/GFR was significantly suppressed in the diabetic children (1.23 versus 1.73 mmol/l, p less than 0.001). This disturbance was neither related to changes in serum parathyroid hormone nor to growth hormone concentrations but was inversely correlated with the degree of hyperglycaemia (r = -0.61, p less than 0.001) and with tubular reabsorption of glucose (r = -0.53, p less than 0.01). In spite of the markedly lowered TmPO4/GFR in the diabetic subjects, the mean maximal (TmPO4) and absolute tubular phosphate reabsorption rates were equal to those of the 28 healthy subjects. Both in the diabetic and healthy subjects, these parameters were positively correlated with glomerular filtration rate which was significantly elevated in the diabetic children (138 versus 109 ml/min per 1.73 m2, p less than 0.01). The study demonstrates a dysfunction in tubular phosphate reabsorption in diabetic children which is related to glycaemic regulation.

Adolescent↗
PubMed1987

Ketone bodies increase glomerular filtration rate in normal man and in patients with type 1 (insulin-dependent) diabetes mellitus.

The purpose of this study was to investigate whether the administration of acetoacetic and hydrochloric acids in a group of control and Type 1 (insulin-dependent) diabetic patients influenced renal haemodynamics. Renal plasma flow increased from 657 +/- 88 to 762 +/- 81 ml X min-1. 1.73 m-2 in diabetic patients (p less than 0.01) and from 590 +/- 71 to 691 +/- 135 in control subjects (p less than 0.01). Glomerular filtration rate increased from 135 +/- 9 to 180 +/- 8 ml X min-1. 1.73 m-2 in diabetic patients (p less than 0.001) and from 117 +/- 8 to 145 +/- 7 in control subjects (p less than 0.01). Similar effects on renal haemodynamics, even if less pronounced, were observed with low dose acetoacetic but not with hydrochloric acid infusion. Total protein, beta 2-microglobulin but not albumin excretion rates were increased by acetoacetic acid. We conclude that an acute increase in blood concentration of ketone bodies within the range found in diabetic patients with poor metabolic control increases renal plasma flow and glomerular filtration rate both in control subjects and diabetic patients and causes a tubular proteinuria.

Acetoacetates↗
PubMed1985

99mTc-DTPA gamma-camera renography: normal values and rapid determination of single-kidney glomerular filtration rate.

A method for 99mTc-diethylenetriaminepentaacetate (DTPA) gamma-camera renography is presented. From each renogram, an uptake index (UI) proportional to the single-kidney glomerular filtration rate (SKGFR) is defined. If the proportionality factor between UI and SKGFR is the same in all patients, UI can be used as an accurate measure of SKGFR. In order to test this, 99mTc-DTPA renography was performed in 101 patients with glomerular filtration rates (GFR) varying between 4 and 172 ml/min. The sum of the right- and left-kidney UIs correlated well with the total GFR calculated from the simultaneously measured plasma clearance of 99mTc-DTPA after a single injection. The correlation coefficient was 0.97. The method was tested in a prospective study of 57 patients. The total GFR estimated from the renograms was not significantly different from the GFR calculated from the plasma clearance of 99mTc-DTPA. The coefficient of variation--a combination of inaccuracy and imprecision in the estimates as well as in the reference values-was 11.8% at a GFR of 100 ml/min. It is concluded that, in adults, the SKGFR can be calculated as part of the clinical routine from 99mTc-DTPA gamma-camera renography without determining the injected dose or collecting urine or blood samples. Normal values for some parameters of the renogram obtained in 25 normal subjects are given.

Adult↗