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At least 1,315 records · Page 73Linked to original sources
PubMed2001

Changes in sodium or glucose filtration rate modulate expression of glucose transporters in renal proximal tubular cells of rat.

Renal glucose reabsorption is mediated by luminal sodium-glucose cotransporters (SGLTs) and basolateral facilitative glucose transporters (GLUTs). The modulators of these transporters are not known, and their substrates glucose and Na+ are potential candidates. In this study we examined the role of glucose and Na+ filtration rate on gene expression of glucose transporters in renal proximal tubule. SGLT1, SGLT2, GLUT1 and GLUT2 mRNAs were assessed by Northern blotting; and GLUT1 and GLUT2 proteins were assessed by Western blotting. Renal cortex and medulla samples from control rats (C), diabetic rats (D) with glycosuria, and insulin-resistant 15-month old rats (I) without glycosuria; and from normal (NS), low (LS), and high (HS) Na+-diet fed rats were studied. Compared to C and I rats, D rats increased (P < 0.05) gene expression of SGLT2 by approximately 36%, SGLT1 by approximately 20%, and GLUT2 by approximately 100%, and reduced (P < 0.05) gene expression of GLUT1 by more than 50%. Compared to NS rats, HS rats increased (P < 0.05) SGLT2, GLUT2, and GLUT1 expression by approximately 100%, with no change in SGLT1 mRNA expression, and LS rats increased (P < 0.05) GLUT1 gene expression by approximately 150%, with no changes in other transporters. In summary, the results showed that changes in glucose or Na+ filtrated rate modulate the glucose transporters gene expression in epithelial cells of the renal proximal tubule.

Animals↗
PubMed1997

Added copper filtration in digital paediatric double-contrast colon examinations: effects on radiation dose and image quality.

Paediatric double-contrast barium enema examinations are usually performed at high tube voltage, 102-105 kV. The aim of this study was to investigate how much the effective dose to the child could be reduced by increasing the X-ray energy further by adding copper filter in the beam, and if this dose reduction could be achieved without endangering image quality. Organ doses to an anthropomorphic phantom simulating a 1-year-old child was measured using thermoluminescence dosimetry for assessment of the effective dose and this value was compared with the energy imparted which was obtained from kerma-area product measurements. To verify that the image quality achieved with this added filtration was still diagnostically acceptable, the study included 15 patient examinations. Since the increased X-ray energy will most probably affect low-contrast objects, image quality was also evaluated with two different phantoms containing low-contrast objects. Effective dose for a complete examination can be decreased 44 % and energy imparted 77 % when a 0.3-mm copper filter is inserted in the beam at tube voltage 102 kV. The patient study did not show any significant deterioration of image quality, whereas phantom measurements of contrast-detail resolution and signal-to-noise ratio was marginally impaired by the added copper filtration. This technique is now in clinical practice for paediatric colon examinations.

Barium Sulfate↗
PubMed2005

Nonselective cyclo-oxygenase inhibitors and glomerular filtration rate in preterm neonates.

The adverse effects of nonselective cyclo-oxygenase (COX) inhibitors on the immature kidney have been described in newborn rabbits, but it is much more laborious and difficult to study its relative impact on renal function in human neonates. Amikacin clearance was therefore used as surrogate marker to study the impact of nonselective COX-inhibitors on glomerular filtration rate. Clinical characteristics and amikacin clearance of infants on respiratory support were retrospectively collected. Results in neonates in whom either ibuprofen-lysine or acetylsalicylic acid was administered prophylactically to induce closure of a patent asymptomatic ductus arteriosus were compared to infants not cotreated with any COX-inhibitor (Mann-Whitney U-, chi-square tests). Amikacin clearance was calculated in 142 infants, of whom 50 were cotreated with ibuprofen and 33 with acetylsalicylic acid. There were no significant differences in clinical characteristics between the three groups. Compared to controls (0.52, range 0.09-2.33 ml/kg/min), a significant similar decrease in amikacin clearance in infants cotreated with ibuprofen (0.38, range 0.13-0.80 ml/kg/min, p<0.01) or acetylsalicylic acid (0.38, range 0.13-0.78 ml/kg/min, p<0.01) was demonstrated. Using amikacin clearance as marker, a significant and similar reduction in glomerular filtration rate was documented in preterm infants cotreated with ibuprofen or acetylsalicylic acid.

Amikacin↗
PubMed2003

Experimental proof of contamination of blood components by (1-->3)-beta-D-glucan caused by filtration with cellulose filters in the manufacturing process.

The level of (1-->3)-beta-D-glucan in blood is a diagnostic index of fungal infection because it is released from the fungal cell wall. However, high levels of plasma (1-->3)-beta-D-glucan in patients administered blood components may give false positive results. High levels of (1-->3)-beta-D-glucan have been detected in blood components. We suspected that (1-->3)-beta-D-glucan from cellulose filters had been eluted into blood components by filtration in the manufacturing process. To investigate the contamination of blood components by (1-->3)-beta-D-glucan from cellulose filters, in vitro experiments were performed by using six cellulose filters and a nylon filter. Human serum albumin (HSA) solution (100 ml) was flowed through each filter after rinsing with 100 ml of distilled water, and (1-->3)-beta-D-glucan in each fraction was determined by Fungitec G test MK. The concentration of (1-->3)-beta-D-glucan eluted from cellulose filters in 100-ml distilled water fractions ranged from 6 to 207 pg/ml, and that of HSA fractions ranged from 33 to 20,784 pg/ml. These data showed that remarkably higher (1-->3)-beta-D-glucan levels were detected in HSA fractions flowed through cellulose filters in spite of advance rinsing with 100 ml of distilled water. In the case of a nylon filter, (1-->3)-beta-D-glucan was not eluted in either fraction. These results indicate that (1-->3)-beta-D-glucan contamination in blood components is caused by filtration with cellulose filters in the manufacturing process.

Blood Chemical Analysis↗
PubMed1983

A rapid filtration assay for soluble receptors using polyethylenimine-treated filters.

Ligand bound to detergent-solubilized or cytosolic receptors can be separated from free ligand by filtration through glass-fiber filters which have been pretreated with polyethylenimine (PEI). Receptors which can be assayed by this technique include detergent-solubilized muscarinic, adenosine A1, alpha 1-adrenergic, alpha 2-adrenergic, beta-adrenergic, dopamine D2, opiate, bradykinin, and benzodiazepine receptors as well as naturally soluble estradiol receptors. For muscarinic, adenosine, alpha 2, dopamine, and estradiol receptors, specific binding measured by the PEI-filter technique was 84-110% of specific binding measured by gel filtration, demonstrating that the technique gave almost quantitative recovery of bound ligand.

Animals↗
PubMed1991

An ultrarapid filtration method adapted to the measurements of water and solute permeability of synthetic and biological vesicles.

An ultrarapid filtration method was adapted to the determination of water and solute permeability of membrane vesicles. This method consisted of measuring substance washout from vesicles first loaded with 3H2O or labeled solutes, placed on filters, and rinsed at high rates for short periods. The retention of the vesicles on the filters was analyzed and was found to be a function of the nature and porosity of the filters as well as of the vesicle origin. Washing buffer flow rate and washing duration did not affect vesicle retention. The diffusional water permeability of cholesterol-free liposomes was determined at 16 degrees C. Its value was reduced by a factor of 2.5 when the liposomes were prepared with 20% cholesterol and a threefold increase was noted when the liposomes were preincubated with gramicidin (6 mg/g lipid). Water permeability of liposomes was strongly temperature-dependent: Ea = 15.3 kcal/mol. Diffusional water permeability of pink ghosts was also measured: a value of (4.4 +/- 0.2) X 10(-3) cm/s (n = 3) was obtained at 13 degrees C. This permeability was reduced by 45.2% with 0.4 mM HgCl2. The urea permeability of intestinal and renal brush-border membrane vesicles was (1.15 +/- 0.18) X 10(-6) cm/s (n = 7) and (1.67 +/- 0.08) X 10(-6) cm/s (n = 9), respectively. The renal value was reduced by a factor of 4.4 by 100 mM thiourea. This ultrarapid filtration technique provides an accurate method of transport measurement in sealed membranes such as liposomes and plasma membrane vesicles.

Animals↗
PubMed1992

Application of cross-flow filtration to the purification of biologically active peptides in human plasma after incubation with a protease-rich extract.

The aim of this study was to find an experimental procedure to purify biologically active peptides from a complex biological matrix (plasma), which was incubated with a protease-rich extract (submandibular gland extract). Special interest was focused on the practicability of cross-flow filtration for this purpose. Therefore, peptides in the incubation mixture were purified with a combination of high-performance liquid chromatographic steps. Purification of biologically active peptides was monitored by a sensitive bioassay and by laser desorption/ionization mass spectrometry. This permitted not only purity control at each purification step but also identification of one of the peptides with vasoconstrictor properties as angiotensin II. This result demonstrates the practicability of cross-flow filtration for extracting enzymatic reaction products from complex substrate-enzyme mixtures during the incubation.

Animals↗
PubMed1979

Non-selective lymphocyte isolation from human blood by nylon wool filtration and density centrifugation.

A new method was employed to isolate lymphocytes from human peripheral blood. Continuous flow filtration through a nylon wool filter, at a flow rate of 1.4 ml/min, produced a lymphocyte yield of 90.5% and a purity of 96% without any shift in the B-T cell ratio. Ficoll-Isopaque with a specific gravity of 1.085 g/ml instead of 1.077 g/ml could be used to remove the erythrocytes. An overall recovery, including defibrination, filtration, Ficoll-Isopaque centrifugation and washing step, of 74.5% was achieved.

B-Lymphocytes↗
PubMed1983

A filtration double antibody radioimmunoassay that simplifies and semi-automates the isolation of immune precipitates.

A semi-automation of fluid phase double antibody radioimmunoassay has been developed. The immune precipitate that was formed in 96-well microtitration plates was harvested and washed on microfibre filters using a Titertek cell harvester. A disc transfer system originally designed for use with the harvester was used as a quick and easy method of transferring the filter discs containing immune precipitate into vials for counting. The results of radioimmunoassay using the microtitration plate-filtration and conventional tube-centrifugation method are essentially identical. The microtitration plate-filtration radioimmunoassay has the following advantages over the conventional tube-centrifugation method: (1) there is no centrifugation required; (2) handling of microtitration plate is easier than the tubes in racks; and (3) it requires much less time to perform the assay.

Animals↗
PubMed1985

An enzyme-linked immuno-filtration assay used to compare infant and maternal antibody profiles in toxoplasmosis.

Enzyme-linked immuno-filtration assay is carried out on a micropore membrane. This doubly analytical technique permits simultaneous study of antibody specificity by immunoprecipitation and characterisation of antibody isotypes by immuno-filtration with enzyme-labelled antibodies. Recognition of the same T. gondii antigenic constituent by IgG, IgA, IgM or IgE antibodies produces couplets (IgG-IgM; IgG-IgA) or triplets (IgG-IgM-IgA; IgG-IgM-IgE) which identify the functional fractions of the toxoplasmosis antigen. In acquired toxoplasmosis, the persistence of IgM antibody long after infestation puts in question the implication of recent infestation normally linked to detection of this isotype. For sera of comparable titres, comparison of immunological profiles by the method described demonstrates disparities in the composition of the specific antibody content as expressed in international units. Use of the same method to detect IgM antibodies or distinguish between transmitted maternal IgG and IgG antibodies synthesised by the foetus or neonate makes a diagnosis of congenital toxoplasmosis possible in 85% of cases during the first few days of life. With the method described the diagnosis may be made on average 5 months earlier than with classical techniques. In the course of surveillance for latent congenital toxoplasmosis, the appearance of IgM or IgE antibodies raises the possibility of complications (hydrocephalus, chorioretinitis). After cessation of treatment, a rise in IgG antibodies indicating persistence of infection is detected earlier by the present than by classical methods.

Antibodies↗
PubMed1986

A competitive enzyme immunoassay of human beta 2-microglobulin based on separation by filtration.

A competitive enzyme immunoassay has been developed for the determination of beta 2-microglobulin in undiluted human serum. In the assay a beta 2-microglobulin-beta-galactosidase conjugate competes with beta 2-microglobulin from the sample for the binding to anti-beta 2-microglobulin antibodies bound to small size agarose particles (micro-Sepharose) via a double antibody. The conjugate is made by providing beta 2-microglobulin with 'reactive disulphide structures.' This is achieved by the heterobifunctional reagent SPDP and the subsequent linkage of the formed derivative to beta-galactosidase by a thioldisulphide exchange reaction. This procedure gives conjugates with high immunoreactivity and enzyme activity. The assay is fast and simple. The reagents are incubated together for 60 min in the wells of a Millititer plate and separation is performed by filtration. Bound enzyme-labelled beta 2-microglobulin is measured by incubation with substrate for 15 min. Both incubations are performed at room temperature without agitation. Due to the high capacity of the micro-Sepharose no sample predilution is needed. The use of the Millititer filtration system gives a rapid and efficient separation and the advantages of access to equipment for dispensing and reading adapted to the microtitre format.

Filtration↗
PubMed1990

A silicon sensor-based filtration immunoassay using biotin-mediated capture.

A sensitive sandwich immunoassay for human chorionic gonadotropin (hCG) was developed with biotin-mediated filtration capture and silicon sensor detection. A high density of biotin on the membrane assured efficient capture of complexes containing streptavidin and analyte. Capture efficiency was not affected over a wide range of filtration flow rates or biotin concentrations. The assay utilized the pH sensing ability of the light addressable potentiometric sensor (LAPS) for the detection of urease-antibody conjugates. A LAPS reader was constructed which allowed the enzyme conjugate to be detected in approximately 1 microliter volumes. Effects from variations in detection volume were studied. 10 pg of hCG could be detected in an assay time of 20 min with four standard deviations separation from background. Comparison to a commercial RIA was made.

Antibodies, Monoclonal↗
PubMed1989

A clinical comparison of image quality and patient exposure reduction in panoramic radiography with heavy metal filtration.

Laboratory and clinical studies with the use of rare earth intensifying screens and four different forms of heavy metal elements serving as additional beam filtration were performed for panoramic radiography to identify the most efficacious system. Balanced density images were evaluated for contrast indices, resolution, relative dose reduction, and subjective image quality. Clinical studies were performed with a standard calcium tungstate imaging system and the four most promising experimental imaging systems that showed improvement over the standard system. Dosimetric studies were performed with the use of ionization chambers and thermoluminescent dosimetry (TLD) dosimeters. Exposure reductions of 34% to 79%, depending on the anatomic site and the imaging system used, were achieved. Subjective image quality was evaluated and analyzed statistically. This study concluded that the use of a Kodak Lanex regular screen/T-Mat G film with either Lanex screen or yttrium added beam filtration results in reduced patient exposure in panoramic radiography while image quality is maintained or improved.

Calcium Compounds↗
PubMed1982

Simultaneous use of a sensitive filtration technique and reagent strips in urinary schistosomiasis.

A sensitive filtration technique and polyvalent urine analysis reagent strips were used simultaneously in patients with urinary schistosomiasis in order to detect pathological conditions other than haematuria and proteinuria. A significant correlation was found between haematuria, proteinuria, leucocyturia and intensity of infection as measured by egg excretion in urine. The best correlation between the reagent strip findings and intensity of infection was obtained when the three parameters were combined. After treatment with metrifonate the reduction of egg excretion was paralleled by the normalization of the reagent strip findings. Analysis of day-to-day variation demonstrated a similar low variation of the filtration technique and the reagent strip findings. Specificity of urine analysis of reagent strips was tested in two age-matched control groups. Although the study was designed only as a pilot study, the results suggests that polyvalent reagent strips may be a useful tool for diagnosis of heavily infected patients under field conditions, as they permit rapid and easy identification of subjects with high egg counts.

Child↗
PubMed1989

Evaluation of a semiautomatic cell harvester filtration for the determination of beta-adrenoceptors in human mononuclear leukocytes.

The ligand affinity (Kd) and the number (Bmax) of beta-adrenoceptors in human mononuclear leukocytes was measured using a semiautomatic cell harvester method for the separation of bound and free ligand. The method was first evaluated in terms of contamination, nonspecific filter binding, and well-to-well reproducibility. A comparison was then made with the conventional manual filtration method. The Kd values for the binding of [125lodo]-cyanopindolol to mononuclear leukocyte membranes were independent of the method, whereas the Bmax values were systematically higher (around 30%) when determined with the cell harvester filtration method. A highly significant correlation was found between the Bmax values obtained with both methods.

Adult↗
PubMed1995

A rapid microtechnique for the estimation of muscarinic and nicotinic receptor binding parameters using 96-well filtration plates.

A microtechnique for the assay of muscarinic and nicotinic receptor binding parameters employing a 96-well filtration multiscreen system has been developed. Utilizing rat cerebral cortex as the receptor source, saturation analysis of [3H]NMS binding revealed a mean Bmax and Kd value of 1.95 pmol/mg protein and 0.71 nM, respectively. In competition studies with atropine a Ki value of 1.67 nM was determined. Nicotinic receptor binding studies were also performed with this technique with [3H]Cytisine. The binding constants for both ligands correlated well with established literature values; however, in the nicotinic assays concentrations of ligand at 20 times the Kd were required to develop adequate number of counts. Compared to presently available receptor binding techniques, this newly developed system for muscarinic and nicotinic binding is very simple and convenient to use and offers the advantages of speed, accuracy and reproducibility. In addition, a large number of samples can be assayed. This report also present the first use of the 96-well filtration multiscreen system for the estimation of muscarinic and nicotinic receptor binding constants. This methodology should prove to be useful for determining the binding characteristics of potential cholinergic ligands.

Alkaloids↗
PubMed1984

Adsorption of influenza viruses to nitrocellulose membrane filters by filtration and their quantitative densitometric determination.

Influenza viruses concentrated and adsorbed onto nitrocellulose membrane filters by filtration are detected rapidly and sensitively by sequential incubation with the primary antibody and the secondary antibody conjugated with peroxidase. The bound enzyme is detected by incubation with a substrate which is converted to an insoluble colored product. A dual-wavelength TLC scanner is used for densitometric quantitation. The membrane filtration-blotting enzyme immunoassay provides a method for quantitative analysis and rapid typing of influenza isolates. The method may be also applicable for quantitative detection of influenza viruses in throat swab specimens from patients, as well as in tissue culture fluids.

Collodion↗
PubMed1990

The efficacy of chlorination and filtration in the control and eradication of Legionella from dental chair water systems.

The apparent failure of hyperchlorination and continuous dosing with chlorine to eliminate legionellae from a dental teaching hospital water supply prompted a prospective study to evaluate charcoal filters as a means of decontamination. Legionella pneumophila serogroup 10 and L. bozemanii serogroup 2 were isolated from dental units yielding 10(1)-10(3) colony forming units (cfu) ml-1 with total bacterial counts in the range 10(2)-greater than 10(4) cfu ml-1. After chair-side installation of charcoal filters bacterial contamination of the dental unit water was prevented and legionellae were initially not detected, but after 7 days the total count returned to pre-filtration levels of greater than 10(4) cfu ml-1; L. pneumophila serogroup 10 was eliminated but L. bozemanii serogroup 2 persisted. These results suggest that neither chlorination nor charcoal filtration deal adequately with the potential hazard of Legionella spp. in dental water.

Charcoal↗