Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FILTRATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59Linked to original sources
PubMed2006

Exendin-4, but not glucagon-like peptide-1, is cleared exclusively by glomerular filtration in anaesthetised pigs.

AIMS/HYPOTHESIS: The insulinotropic hormone, glucagon-like peptide-1 (GLP-1), is rapidly degraded in vivo as a result of the combination of extensive enzymatic degradation and renal extraction. The GLP-1 receptor agonist, exendin-4, has a longer duration of action, and has recently been approved as a new agent for the treatment of type 2 diabetes mellitus. Exendin-4 is less prone to enzymatic degradation, but it is still unclear what other factors contribute to the increased metabolic stability. MATERIALS AND METHODS: The overall metabolism of GLP-1 and exendin-4 was directly compared in anaesthetised pigs (n=9). RESULTS: Metabolism of GLP-1 (C-terminal RIA; t (1/2) 2.0+/-0.2 min, metabolic clearance rate [MCR] 23.2+/-2.8 ml min(-1) kg(-1); N-terminal RIA; t (1/2) 1.5+/-0.2 min, MCR 88.1+/-10.6 ml min(-1) kg(-1)) was significantly faster than the metabolism of exendin-4 (t (1/2) 22.0+/-2.1 min, p<0.0001; MCR 1.7+/-0.3 ml min(-1) kg(-1), p<0.01). Differences in arteriovenous concentrations revealed organ extraction of GLP-1 by the kidneys (C-terminal 56.6+/-2.6%; N-terminal 48.3+/-5.9%), liver (N-terminal 41.4+/-3.8%), and peripheral tissues (C-terminal 42.3+/-6.0%; N-terminal 33.0+/-7.8%), whereas organ extraction of exendin-4 was limited to the kidneys (21.3+/-4.9%). While the renal extraction of exendin-4 (6.9+/-2.5 pmol/min) did not differ significantly from the amount undergoing glomerular filtration (8.4+/-2.0 pmol/min), the renal extraction of C-terminal GLP-1 (9.0+/-1.1 pmol/min), exceeded the amount which could be accounted for by glomerular filtration (4.2+/-0.5 pmol/min, p<0.0005). CONCLUSIONS/INTERPRETATION: In addition to an increased resistance to enzymatic degradation, the increased stability of exendin-4 is the result of reduced differential organ extraction compared to GLP-1. The data suggest that in the anaesthetised pig, extraction occurs only in the kidney and can be fully accounted for by glomerular filtration.

Anesthesia↗
PubMed2000

In-vitro selection of Vitis vinifera 'Chardonnay' with Elsinoe ampelina culture filtrate is accompanied by fungal resistance and enhanced secretion of chitinase.

Proembryogenic masses of grapevine (Vitis vinifera L.) 'Chardonnay' (clone 02Ch) were exposed to the culture filtrate of Elsinoe ampelina (deBary) Shear, the causal agent of anthracnose disease. After four or five cycles of recurrent in-vitro selection with medium containing 40% fungal culture filtrate, putative resistant lines RC1 and RC2 respectively, were established. The selected lines inhibited the growth of E. ampelina and Fusarium oxysporium (Schlecht.) (isolated from watermelon) in a dual-culture assay and reduced the growth of mycelium on a conditioned-medium test, thus suggesting the involvement of extracellular compounds in resistance. Sodium dodecyl sulfate-polyacrylamide (SDS-PAGE) gel electrophoresis of extracellular proteins from spent suspension-culture medium showed enhanced secretion of new proteins by selected lines. A 36-kDa protein was immunodetected by a chitinase antiserum. This chitinase continued to express constitutively in differentiated somatic embryos and also in the intercellular fluids of plants regenerated from the selected lines. Somatic embryos from selected lines grew uninhibitedly in a medium containing 40% fungal culture filtrate, whereas non-selected (control) somatic embryos became necrotic and died within a few days. Plants regenerated from selected lines exhibited resistance to infection by E. ampelina in both greenhouse tests and detached leaf bioassays. Results suggest that embryogenic cells can be selected for resistance following in-vitro selection, resulting in resistant plants. Whether or not resistant cells pre-existed in the original embryogenic culture or were induced by the selection pressure could not be determined.

Ascomycota↗
PubMed1984

Reopening filtration fistulas with transconjunctival argon laser photocoagulation.

Three patients (a 15-year-old girl, a 45-year-old woman, and a 61-year-old woman) with previously successful full-thickness filtering procedures developed pigmented tissue in the fistula sites and uncontrolled intraocular pressures despite maximum tolerable medical therapy. The filtering procedures in the first and second patients spontaneously failed two and four years after surgery. The filtration bleb of the third patient, after successfully controlling intraocular pressure for six years, failed two months after cataract extraction. Argon laser therapy was applied through the conjunctiva to treat visible subconjunctival pigmented tissue within the sites of the previous surgical filtration blebs. In all three cases, there was an immediate and significant decrease in intraocular pressure associated with reestablishment of the filtration bleb (from 44 to 16 mm Hg in Case 1, from 40 to 15 mm Hg in Case 2, and from 25 to 12 mm Hg in Case 3). Long-term follow-up showed well controlled intraocular pressures without glaucoma medications (Case 1, 5 mm Hg after 18 months; Case 2, 17 mm Hg after one year; and Case 3, 9 mm Hg after five months).

Adolescent↗
PubMed1991

Radioimmune assay of sialyltransferase and N-acetylgalactosaminyltransferase activities using specific antibodies on a 96-well filtration plate of a multiscreen assay system.

A new assay method for glycosphingolipid glycosyl-transferase activities was developed using a 96-well filtration plate of a MultiScreen assay system. An acceptor glycosphingolipid and a donor radioactive nucleotide sugar were incubated with an enzyme source in a well of the filtration plate. After incubation, both identification and quantification of the reaction product were carried out simultaneously using a specific antibody for the product which was trapped on a filtration membrane of the plate as a complex with Staphylococcus aureus protein A (IgGSorb). This assay method was used for determining the activity of cytidine 5'-monophosphate-N-acetylneuraminic acid:Lcn4Cer alpha 2----6sialyltransferase and uridine 5'-diphosphate-N-acetyl galactosamine:GM3 N-acetylgalactosaminyltransferase. In addition to the simple and rapid identification and quantification of the product, this method proved to be as reliable and sensitive as the previously published assay procedures. Furthermore, this assay method can be used with a high concentration of detergent which should not be used in the other procedures described previously using enzyme-linked immunosorbent assay methods on a 96-well multiplate even if the enzyme reaction might require a certain percentage of the detergent concentration.

Animals↗
PubMed1988

Association-dissociation studies of bovine and rat liver glutamic dehydrogenase by high-performance liquid chromatography gel filtration.

The concentration-dependent association-dissociation tendency of purified bovine liver and rat liver glutamic dehydrogenase (GDH) has been demonstrated by high-performance liquid chromatographic gel filtration. In the concentration range of 100 to 1.0 micrograms bovine GDH/ml molecular species ranged from dimer and unimer to subunimeric forms. The dissociation process of the unimeric hexapeptide, consisting of six polypeptide chains, to the subunimeric tripeptide, consisting of three polypeptide chains, was irreversible without added ionic support, but reversible with added ionic support. In dilute Tris-HCl bovine liver GDH was dispersed to subunimeric sizes. Increasing the ionic strength in 20 mM phosphate as the mobile phase increased dissociation to a subunimeric tripeptide while sustaining as much as 80% of its activity. Activity of a eluting subunimer was verified by the inclusion of reaction substrates (NAD and glutamute) in the mobile phase and quantification of reaction products (NADH) in chromatograms. Gel filtration of GDH in the presence of GTP with NADH rendered a subunimeric tripeptide, largely independent of ionic strength or GDH concentration. Rat liver GDH, differing from bovine liver GDH, was dissociated by gel filtration to an active tripeptide independent of ionic or buffer conditions.

Adenosine Diphosphate↗
PubMed1983

Absorption filtration. A tool for the measurement of ion tracer flux in native membranes and reconstituted lipid vesicles.

A rapid, simple and reproducible method has been developed for the measurement of ion tracer flux with both native membrane vesicles and reconstituted lipid vesicle systems. Following the absorption of vesicles onto glass fiber filters, tracer flux is performed directly upon the deposited samples. In contrast to the more conventional vacuum and gel filtration techniques, absorption filtration exhibits comprehensive data retrieval whereby the removal of extravesicular ions, the retention of intravesicular ions and the amount of ions fluxed can be accurately analyzed. Both influx and efflux assays have been designed to measure the carbamylcholine-induced flux of 22Na+ which is characteristic of acetylcholine receptor-enriched membranes from Torpedo californica electroplax. The flux signal-to-background noise ratio is maximized in the efflux assay, since agonist activation is performed subsequent to the exhaustive removal of extravesicular tracer. An interesting feature of the influx assay is that the agonist-induced uptake of 22Na+ can be repeated with the original vesicles which additionally maximizes the flux signal. With either approach, the inactivation of ionophoric activity due to prolonged exposure to agonists ('desensitization') can be reversed upon removal of agonist without dilution of the deposited samples. Due to the large array of glass fiber filters and ion-exchange disks, the absorption filtration technique should be able to accommodate the transport and binding of soluble molecules to a variety of intact cells, membranes and reconstituted lipid vesicles.

Absorption↗
PubMed1990

Effect of experimental conditions on the appearance of distinct forms of placental glucosylceramidase: use of gel filtration analysis as a means of ascertaining their occurrence.

We have found that, under some experimental conditions, the placental glucosylceramidase shows an anomalous behaviour on gel filtration chromatography. At pH 5.6, the optimal pH of the enzymatic assay, the purified enzyme remains bound to either Superose 6 or TSK-40-XL HPLC columns, while the interaction of the crude glucosylceramidase contained in the water extract of the lysosome-mitochondrial fraction of placenta with the two HPLC gel matrices is much weaker. The quite different behaviour of the crude compared to the purified enzyme may be explained by the formation in the crude preparation of associated form(s) of glucosylceramidase with suitable endogenous compound(s), which compete with the gel matrices for the binding to the enzyme. The most likely one component of the enzyme complex is the placental activating factor, previously reported by us (Vaccaro et al. (1985) Biochim. Biophys. Acta 836, 157-166), as indicated by the negligible stimulation of the crude enzyme activity on addition of the factor, either before or after passage through the HPLC columns. On the assumption that the behaviour of crude glucosylceramidase on gel filtration becomes similar to that of the purified enzyme when its interaction with endogenous substance(s) is impaired, we have identified some conditions which prevent the formation of the enzyme associated form(s): (a) the addition of guanidine chloride (0.2 M), a cahotropic agent, to the crude preparation; and (b) the increase of pH up to 8. In conclusion, taking advantage of the anomalous behaviour of glucosylceramidase on gel filtration chromatography, evidence has been obtained that placental glucosylceramidase may occur under several forms which had not been previously reported; a difference in experimental conditions can promote the formation of one or another form, by possibly affecting the composition and/or the stoichiometry and/or the stability of the enzyme complex.

Chromatography, Gel↗
PubMed1995

Anions and the anomalous gel filtration behavior of notexin and scutoxin.

Based on their mol. wts, notexin and scutoxin elute later than expected from gel filtration columns in multiple peaks [Francis et al. (1991) Toxicon 29, 85-96]. Notexins present in these peaks have identical amino acid sequences and unmodified amino acid side-chains. Scutoxin is an isoform of notexin which contains arginine at position 16 and glutamate at position 82. Like notexin, it also elutes in different fractions on a gel filtration column, yet the fractions show identical amino acid sequence. This perplexing chromatographic behavior appears to be caused by the association of these proteins with different anions, since dissolving notexin in buffers containing different anions produces up to a 30% change in elution volume. Certain anions promote an apparent reduction in the interaction of notexin with gel filtration matrix, hence earlier elution. These anions include citrate, 3-phosphoglycerate and 2-phosphoglycerate, which also inhibit the PLA2 activity of notexin. However, even under conditions which minimize protein-matrix interaction the toxins elute later than expected based on their mol. wt.

Amino Acid Sequence↗
PubMed1995

Effect of filtration on post-thaw quality of bull semen.

Semen from 4 Holstein bulls was diluted in 4 different extenders, filtered with Sephadex ion-exchange column, and frozen in liquid nitrogen. Sperm motility, progressive motility, path velocity, progressive velocity and the percentage of normal acrosomes of filtered and nonfiltered semen were recorded before and after freezing. Semen characteristics were significantly influenced by extender, filtration and freezing. Before and after freezing, motility measurements and the percentage of normal acrosomes were higher (P < 0.001) in filtered than in nonfiltered spermatozoa. Post-thaw recovery rate of motile spermatozoa was higher in filtered semen than nonfiltered (68 vs 39%, P < 0.0001). The reduction in motility, progressive motility and the percentage of normal acrosomes during freezing and thawing processes were significantly lower (P < 0.0001) in filtered semen (34, 34 and 4%, respectively) than nonfiltered (59, 54 and 15%, respectively). Post-thaw viability of spermatozoa was significantly affected by extender, filtration and time (P < 0.0001). Immediate (0 h) post-thaw motility of nonfiltered semen (29%) was similar to 4-h post-thaw motility of filtered semen (25%; P > 0.05). In conclusion, bull spermatozoa recovered by Sephadex ion-exchange filtration showed better post-thaw viability.

Journal Article↗
PubMed1996

Role of sperm motility and acrosome integrity in the filtration of bovine semen.

In this study, the role of sperm motility and acrosome integrity in filtration of bovine semen was investigated. In Experiment 1, the treatment of semen with formaldehyde, hyperosmotic buffer, heating and direct freezing immobilized the spermatozoa completely but their acrosomal status varied significantly (P < 0.01). The immotile spermatozoa, of any kind, did not pass through the Sephadex ion-exchange column at room temperature. In Experiment 2, semen samples possessing different percentages of immobilized spermatozoa (0, 50, 75 and 100%) were filtered through the Sephadex ion-exchange column. The immotile/dead spermatozoa were removed proportionately to their number in the semen by Sephadex ion-exchange column. The type and number of immotile spermatozoa in semen had no effect (P > 0.05) on the post-filtration recovery rate of motile spermatozoa. Filtered spermatozoa exhibited higher (P < 0.01) motility (> 90%), progressive motility (> 70%) and normal acrosomes (> 95%) than non-filtered spermatozoa. In conclusion, sperm motility seems to be more important than acrosome integrity for semen filtration, and the Sephadex ion-exchange column can remove the known quantities of different kinds dead/immotile spermatozoa.

Journal Article↗
PubMed1995

Responses of bovine T cells to fractionated lysate and culture filtrate proteins of Mycobacterium bovis BCG.

Bacterial cell lysates and culture filtrate proteins of Mycobacterium bovis BCG were each separated in a two-dimensional system that yields soluble protein fractions immediately available for probing with T cells. The fractions were used in lymphocyte proliferation assays using blood lymphocytes from cattle immunized with either viable or gamma-irradiated BCG. Cattle immunized with either form of BCG responded similarly to fractionated lysate proteins. Cattle immunized with viable BCG responded to culture filtrate proteins that were not recognized by cattle immunized with dead BCG. Marked heterogeneity of the responses to the culture filtrate proteins was seen.

Animals↗
PubMed1991

Air pollution and agricultural aphid pests. II chamber filtration experiments.

The responses of four major aphid pest species feeding on three major crops were studied in a series of experimental chambers on the roof of Imperial College in South Kensington, London. The experimental chambers were continually circulated with air which had been subjected to a variety of filtration treatments. In the first series of experiments there were three chambers subject to ambient air, charcoal-filtered air, and charcoal plus 'Purafil'-filtered air; in the subsequent experiments there were four chambers, a charcoal plus 'Purafil' plus charcoal treatment being added. These treatments provided a range of concentrations and mixtures of the ambient gases present at the site. The growth rate of aphids was measured both during filtration and post-filtration, the plants being exposed from sowing for either 42 or 84 days. In all cases there were significant effects on aphid performance which seemed to be most strongly linked to absolute and relative NO concentrations. The pattern of responses by the aphids accorded extremely well with those observed in closed-chamber fumigation experiments with stimulation of performance in relatively polluted air in all cases except Acyrthosiphon pisum (Harris) feeding on Vicia faba L. where the opposite effect was recorded.

Journal Article↗
PubMed1994

Short-term effects of metals on the filtration rate of the zebra mussel Dreissena polymorpha.

In order to study the short-term ecotoxicity of metals to the freshwater mussel Dreissena polymorpha, the effects of Cu, Zn and Cd on the filtration rate of this mussel were determined in laboratory experiments. Filtration rate was chosen as the endpoint, because it is a sensitive sublethal parameter compared to mortality and it is an important parameter given the ecological role D. polymorpha fulfills. The filtration rate was calculated from the decrease in algal concentration, fed to mussels in aquaria, containing different metal concentrations. The EC50 for Cu (41 microg litre(-1)) was lower than for Cd (388 microg litre(-1)) and Zn (1350 microg litre(-1)). The NOEC(accumulation) for the essential metal Zn was higher than for the essential metal Cu. Cadmium, a non-essential metal, was accumulated at all elevated water concentrations, so the NOEC(accumulation) was the concentration in the control water (<0.2 microg litre(-1)). All (no) effect concentrations found in this study were above the quality criteria set for metal concentrations in Dutch surface water, suggesting that the zebra mussel is sufficiently protected by these quality criteria.

Journal Article↗
PubMed1995

Protective activity and antigenic analysis of fractions of culture filtrates of Erysipelothrix rhusiopathiae.

The protective activity in mice and antigenic composition of the culture filtrate of 11 strains of Erysipelothrix rhusiopathiae were compared. Protective activity was found in the first (P-1) fraction obtained by Sephadex G-200 gel filtration of the culture filtrate of each strain. Comparing the 50% protective dose (PD50) of the P-1 fraction of the 11 strains by active immunization, highly protective activity was shown by 5 strains, such as Agata, Fujisawa, Shizuoka-63, Koganei 65-0.15 and SE-9. For the 50% effective dose (ED50) determined by passive protective studies, the four strains, Agata, Fujisawa, Koganei 65-0.15 and SE-9 were shown to be highly protective. However, strains 2179 and 2553 showed low activities in both PD50 and ED50. The highly and weakly protective strains were compared by western blot analysis for the protein components. In most strains tested, there were two protein bands of molecular weight of 64 kDa and 43 kDa. Therefore, these two structural proteins were common to the strains and were associated with stimulation of a protective effect in mice.

Animals↗
PubMed1994

Filtration of fentanyl is not the cause of the elevation of arterial blood pressure associated with post-bypass ultrafiltration in children.

Modified ultrafiltration after cardiopulmonary bypass in children has been shown to be associated with an increase in arterial blood pressure. As part of a series of studies to investigate the possible causes of this blood pressure elevation, the hypothesis that if filtration was removing a significant amount of fentanyl, then the increase in blood pressure might be due to pain was proposed. Ten children, aged between 0.5 and 9.3 years (median 3.8 years), weighing 5.9 to 25.5 kg (median 15.7 kg), underwent corrective cardiac surgery (incorporating modified ultrafiltration). A standard anesthetic protocol was followed, with up to 78 micrograms/kg of fentanyl given prebypass for analgesia. After completion of cardiopulmonary bypass, modified ultrafiltration was commenced at 100 mL/min until a hematocrit of 35% was reached. Samples were taken of arterial blood (prefiltration, 3, 10, and 20 minutes postfiltration), the venous reservoir blood (prefiltration) and the filtrate (5 and 10 minutes into filtration). Hemodynamic data were recorded both prefiltration and postfiltration. The hemodynamic data showed the expected rise in both systemic arterial pressure and cardiac index after ultrafiltration. The plasma fentanyl concentrations did not significantly change after ultrafiltration: 1.59 to 12.39 ng/mL (median 6.27 ng/mL) prefiltration and 2.05 to 15.59 ng/mL (6.29 ng/mL) at 3 minutes, 2.22 to 12.64 ng/mL (6.87 ng/mL) at 10 minutes, and 1.83 to 11.52 ng/mL (5.85 ng/mL) at 20 minutes postfiltration.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia↗
PubMed2005

Management of Meloidogyne incognita on tomato by root-dip treatment in culture filtrate of the blue-green alga, Microcoleus vaginatus.

The nematicidal potential of culture filtrates of the blue-green alga, Microcoleus vaginatus (Cyanobacterium) was tested against Meloidogyne incognita on tomato in pots under greenhouse conditions. Prior to the transplantation of tomato seedling, roots were dipped in different concentrations (0.2%, 0.5%, 1%, 2%, 10%, 50% and 100%) of culture filtrate of M. vaginatus for 30 min. Root-dip treatment reduced the root galling and final population of M. incognita and increased vegetative growth of plants and root-mass production compared with the control. The beneficial effect of root-dip treatment increased with the increase in the concentration of culture filtrate. Root galling and final nematode populations were reduced by 65.9% and 97.5%, respectively when treated at the highest concentration.

Animals↗
PubMed2006

Increasing the scale of true moving bed electrophoretic separations using filtration to reduce solvent volumetric flows between sections II and III.

Over the past decade the moving bed process has become a commonly used tool for the continuous separation of chiral compounds, and its recent application to electrophoretic separations allows the technique to be used as a model system for moving bed method improvements. Much of the recent research on moving bed separations has focused on improving the technique's efficiency and increasing the maximum attainable throughput. This paper presents a novel method for reducing or reversing the increases in tailing that stem from the addition of the feed stream in a moving bed process by adding a filtration unit which retains the products while removing fluid from the boundary between the sections above and below the feed stream. This filtration-enhanced moving bed process was applied to a true moving bed (TMB) electrophoresis separation in the Vortex Stabilized Electrophoresis Apparatus, and its effect on a homatropine enantiomer separation was studied. Experiments showed that there is a 2.4-fold increase in the homatropine processing rate when 0.5 ml/h of water is removed through a reverse osmosis filter at the boundary between the sections above and below the feed stream. In order to further understand the process, filtration-enhanced TMB (FE-TMB) was also analyzed using a linear model of the system which shows that the 99% purity operating region of the separation is greatly increased even with moderate permeate flowrates.

Adsorption↗
PubMed2004

Use of autotrophic sulfur-oxidizers to remove nitrate from bank filtrate in a permeable reactive barrier system.

This study was conducted to evaluate the potential applicability of an in situ biological reactive barrier system to treat nitrate-contaminated bank filtrate. The reactive barrier consisted of sulfur granules as an electron donor and autotrophic sulfur-oxidizing bacteria as a biological component. Limestone was also used to provide alkalinity. The results showed that the autotrophic sulfur oxidizers were successfully colonized on the surfaces of the sulfur particles and removed nitrate from synthetic bank filtrate. The sulfur-oxidizing activity continuously increased with time and then was maintained or slightly decreased after five days of column operation. Maximum nitrate removal efficiency and sulfur oxidation rate were observed at near neutral pH. Over 90% of the initial nitrate dissolved in synthetic bank filtrate was removed in all columns tested with some nitrite accumulation. However, nitrite accumulation was observed mainly during the initial operation period, and the concentration markedly diminished with time. The nitrite concentration in effluent was less than 2 mg-N/l after 12 days of column operation. When influent nitrate concentrations were 30, 40, and 60 mg-N/l and sulfur content in column was 75%, half-order autotrophic denitrification reaction rate constants were 31.73 x 10(-3), 33.3 x 10(-3), and 36.4 x 10(-3) mg(1/2)/l(1/2)min, respectively. Our data on the nitrate distribution profile along the column suggest that an appropriate wall thickness of a reactive barrier for autotrophic denitrification may be 30 cm when influent nitrate concentration is less than 60 mg-N/l.

Hydrogen-Ion Concentration↗