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At least 1,261 records · Page 70Linked to original sources
PubMed1996

Cytokine production by human peripheral blood mononuclear cells stimulated by a Pseudomonas aeruginosa culture filtrate: role of plasma and polymyxin B.

The lack of consensus regarding the significance of transmembrane passage of bacterial products across hemodialysis membranes can be related to several methodological differences in the various studies, including the choice of circulating fluid in the blood compartment of the model, nature and concentration of the bacterial products employed to challenge the dialysate compartment and whether cytokine production by PMBC or the limulus amebocyte lysate (LAL) assay was used as the index of transfer and the cytokine used as the read-out. In this study, we examined the production of interleukin-1 alpha (IL-1 alpha), interleukin-1 receptor antagonist (IL-1Ra) and interleukin-8 (IL-8) by peripheral blood mononuclear cells (PBMC) incubated with a Pseudomonas aeruginosa culture filtrate. Further, the effects of 10% autologous human plasma and Polymyxin B sulfate (PmB) on cytokine production by PBMC were also characterized. The results of our study indicate that the Ps. aeruginosa culture filtrate had both PmB suppressible and PmB non-suppressible components and that the addition of 10% human plasma significantly enhanced cytokine production by both PmB suppressible and PmB non-suppressible components. The enhancing effect of plasma was most evident at low concentrations of the filtrate. The inhibitory effect of PmB was most evident in samples cultured in the presence of 10% plasma. There was a direct correlation between the production of IL-1 alpha and IL-1Ra suggesting that both pro-inflammatory cytokines and cytokine-specific inhibitory proteins are concurrently produced. There results have direct relevance to selection of study conditions for in vitro models used to study the transmembrane passage of bacterial products across hemodialysis membranes.

Anti-Bacterial Agents↗
PubMedDate not supplied

Pulsed flow cascade filtration. Long-term experience in low density lipoprotein and lipoprotein a removal.

The authors present the results of pulsed flow cascade filtration (PFCF) for low density lipoprotein (LDL) and lipoprolein a (La) removal in four patients with familial hypercholesterolemia. Forty-six treatments were performed. Pressure and flow pulsations were superimposed on the retentate of the secondary filter using a modified single roller peristaltic pump. The pulsation frequency was adjusted to achieve, on average, zero retentate flow (dead end filtration). The transmembrane pressure and sieving coefficients of immunoglobulin G, apolipoprotein A1, and apolipoprotein B of the secondary filter remained constant during filtration periods of 150 min. The PFCF technique was found to remove more LDL and La than did adsorption on dextran sulfate columns, while maintaining adequate albumin recovery (90%).

Blood Component Removal↗
PubMed1996

[Mechanisms of metabolic changes after in-line filtration of erythrocytes].

BACKGROUND: The reasons for the improved RBC storage after in-line filtration are not fully understood. MATERIAL AND METHODS: Red blood cell concentrates were in-line filtered and stored for 6 weeks at 4 degrees C in SAGM. Parameter 2,3-DPG, p50, density, cell electrophoresis, pH were measured. RESULTS/CONCLUSION: The obtained results may explain the metabolic findings: Cell retention (during filtration older, rigide RBC are retained in the filter- a relative increase of younger RBC); changes in RBC membrane permeability (a changed electrophoretic mobility is attributed to bound RBC membrane proteins to the filter material); blood cell depletion (a high depletion efficiency prevents toxic influences of degenerating/disintegrating WBC and PLT); release of substances from filter and blood bag material (during passage of anticoagulated blood some compounds may be released in ppm concentrations - the density of in-line filtered RBC is higher than unfiltered RBC after filtration procedure and hypothermic storage).

2,3-Diphosphoglycerate↗
PubMed1996

[Studies of changes in filtration angle after experimental administration of ethacrynic acid into the anterior chamber].

The aim of the study is to determine what charges occur in filtration angle after administration of ethacrynic acid solution into anterior chamber. The study was conducted in 9 rabbits. After administration of 0.5 mmol/l and 0.7 mmol/l epsilon. acid solution, oedema of cells, relaxation of structure of trabecular texture and cellular necrobiosis in filtration angle were detected. Intraocular pressure lowered by 6-7 mm Hg. It is possible that ethacrynic acid will be used as an agent inducing changes in filtration angle which reduce intraocular pressure.

Animals↗
PubMed1997

[Microbiological control of drugs with antimicrobial properties with membrane filtration: problems, proposals, prospects].

The attention to the difficulty to performing the control of sterility (and also of contamination) of pharmaceuticals with antimicrobial activity (antibiotics, chemotherapeutic agents, etc.) or containing preservatives is called. On the basis of our and others investigations, the technique of the membrane filtration (employed usually) is unable to eliminate the interferences on the microbial growth. The membranes used for the filtration of antimicrobial agents acquire antimicrobial properties, resulting in: a) appearance of inhibition zones onto agar plates previously inoculated with microbial strains; b) decrease of the number of CFU after artificial contamination of the membranes (more sensitive method); c) absence or partial growth into culture broths of microbial strains contaminant the membranes; d) antimicrobial activity of the culture broths inoculated with used membranes. The separate washing with 300 ml and upper volumes of peptone water does not eliminate completely the antimicrobial activity of the membranes. If the filtration is associated to treatments with suitable neutralisant substances, it is possible to eliminate partially the antimicrobial activity of the membranes. In No. 10 antibiotics, a total neutralization of the antimicrobial activity was obtained in No. 4 cases (40%). In No. 14 chemotherapeutic agents, We have obtained a total neutralization of the antimicrobial activity in No. 11 cases (78.57%) and a partial remission in No. 3 cases (21.43%). In No. 18 disinfectant, We have obtained a complete disappearance of the drawback in No. 16 (88.8%) cases and a partial disappearance in No. 2 (11.2%) cases. Only in the case of the preservatives (No. 3 single and 16 associations), we have obtained a total remission of the interferences in all cases. For the neutralization, some classic neutralizers (albumin, p-aminobenzoic acid, beta-lactamase, cysteine, Ca+2, egg yolk, Fe+3, heparin, hydroxylamine, thymidine, Tween 20) and a new neutralizing agent (ascorbic acid) were employed. Thus, it is necessary to find suitable neutralizing agents or to research new types of filtering membranes. In the meantime, the production of chemo-antibiotic agents should be carried out according to stingent criteria of asepsis.

Anti-Infective Agents↗
PubMedDate not supplied

[The toxin-containing filtrates from the culture broths of clinical strains of Corynebacterium diphtheriae].

Composition as well as toxicity and antigenicity of toxin-including filtrates of 6 circulating strains of Corynebacterium diphtheriae, isolated in 1992-1994 in the city of Kharkiv have been studied as compared with production strain PW-8. It is shown that toxicity of filtrates of circulating strains was analogous of toxicity of the strain PW-8 (100 dlm) or lower (45 dlm). Antigenicity of four strains which was expressed in if units proved to be higher than that of the production strains and it was considerably higher in two strains isolated from adults who died from diphtheria. The methods of gel-filtration and immunoprecipitation were used to establish differences between strains in their capacity to preferential accumulation of different molecular forms of toxin under stationary cultivation.

Adult↗
PubMed1998

The effect of paclitaxel powder on glaucoma filtration surgery in rabbits.

OBJECTIVE: The authors determine if the intraoperative placement of paclitaxel powder in the subconjunctival space improves the outcome of glaucoma filtration surgery in rabbits. METHODS: A posterior lip sclerectomy was performed in the right eye of 24 New Zealand white rabbits. Before the conjunctiva was fully sutured, 8 mg of mannitol powder alone, or 8 mg of mannitol powder containing either 10 micrograms or 250 micrograms of paclitaxel, was placed in the subconjunctival space of six eyes each in masked fashion. An additional six animals were treated with episcleral application of a sponge soaked in a solution of 0.5 mg/ml of mitomycin C (MMC) for 5 minutes before the sclerectomy was performed. Intraocular pressure and bleb size were measured until the operation had failed or until the 7 weeks of observation had concluded. RESULTS: Both paclitaxel powder and MMC solution improved the outcome of filtration surgery in this model as measured by magnitude of intraocular pressure (IOP) lowering and duration of surgical success. No toxic effect of either drug was observed, although endophthalmitis was observed in eight animals followed for more than 3 weeks. CONCLUSION: The introduction of paclitaxel into the subconjunctival space at the conclusion of filtration surgery has an effect comparable to intraoperative MMC.

Animals↗
PubMed1998

Ultrastructural changes of the filtration barrier during mouse nephron development.

The development of mouse renal corpuscles localized in the juxtamedullary zone of renal cortex was assessed with the aid of light and electron microscopy. The observations have confirmed the existence of four developmental phases of the nephron. The analysis of filtration barrier components has shown that during the development of the kidney the height of maturing podocytes becomes markedly reduced, and that adherence and occluding junctions formed between them shift from their apices towards their bases. Ladder-like junctions have also been observed between podocytes. The number of their foot processes steadily grows, they become narrower and filtration slit diaphragms begin appear between them. Fusion of podocytes basement membranes and endotheliocytes leads to formation of a doubly thick filtration membrane. As the tuft of the capillary glomerulus grows, newly formed fragments of the basement membrane in the form of loops and pouches start to be evident in its close neighborhood. Large endotheliocytes become greatly flattened and numerous fenestrae appear in their cytoplasm.

Animals↗
PubMed1997

Consistency of nephron filtration measurements by collection of total tubular fluid from different proximal sites.

The stability of single nephron glomerular filtration rate (SNGFR) is assured by specific mechanisms such as the tubulo-glomerular feedback system and autoregulation. Studies on renal physiology rely heavily on the measurements of SNGFR, which are feasible only in animals. The measurement of SNGFR by collection of total tubular fluid may be influenced by the fall in intratubular hydrostatic pressure that may reflect the negative pressure applied to the sampling pipette. This effect may become more important with shortening of the distance between the sampling site and the Bowman space. We analysed this putative effect by performing collections of total tubular fluid from the late proximal (LP), and then from the early proximal (EP) segment of the same nephrons. In 128 paired collections LP-SNGFR averaged 35 (SEM 2) nl x min(-1), and was no different from the paired mean EP-SNGFR of 37 (SEM 2) nl x min(-1), P > 0.179. Then EP- and LP- SNGFR were significantly correlated (r = 0.77, P < 0.001). As expected, the respective paired means of absolute and percentage reabsorptions, and those of collection rates were significantly different. The average SNGFR computed from each LP and EP paired measurement was significantly correlated with the simultaneously measured kidney glomerular filtration rate, GFR (r = 0.60, P < 0.0001). The ratio of GFR to SNGFR indicated the expected number of glomeruli. These data would indicate that the sampling site does not influence the measurement of SNGFR in the proximal tubule when the total fluid collection technique is correctly performed. They also exclude a time-dependent activation of the macula densa capable of upregulating SNGFR within the interval elapsing between the beginning of LP and the completion of EP collections, which in our study averaged 4.4 (SEM 0.1) min.

Animals↗
PubMed2026

Metagenomic insights into microbial drivers of organic micropollutant removal in wastewater-impacted riverbank filtration.

Organic micropollutants (OMPs) in wastewater treatment plant (WWTP) effluent pose persistent risks to aquatic ecosystems and drinking water sources. Riverbank filtration (RBF) is a nature-based treatment process, yet the compartment-specific roles of riverbed sediment and downstream soil in OMP attenuation remain poorly resolved under wastewater-impacted conditions. Here, we combined targeted chemical analysis, OMP property compilation, shotgun metagenomics, EnviPath-based biotransformation annotation, and exploratory network analysis to investigate OMP attenuation in a laboratory-scale RBF system treating real WWTP effluent for 10 months. Nineteen OMPs were monitored along a sequential sediment-soil filtration pathway. Sediment preferentially attenuated hydrophilic or charged compounds, including lidocaine, amantadine, and sotalol, whereas soil contributed more strongly to the attenuation of naproxen, atenolol, and losartan. Metagenomic profiling revealed distinct microbial communities and functional gene repertoires between sediment and soil after long-term operation. Sediment harbored higher relative abundances of genes associated with oxidative xenobiotic transformation, including cytochrome P450-related enzymes, demethylases, dehydrogenases, oxidases, and aromatic compound degradation pathways. An exploratory Spearman network further identified associations among microbial genera, EnviPath-annotated candidate biotransformation genes, and OMP removal rates, including 17 KO-OMP links supported by both correlation and pathway annotation. These findings indicate that sediment and soil develop complementary microbial functional potentials that may support compound-specific OMP attenuation. This study provides a mechanistic basis for optimizing sediment-soil configurations in wastewater-impacted RBF systems and for improving nature-based barriers against diverse OMP mixtures.

Wastewater↗
PubMed1993

The role of the glomerular epithelial cell in the maintenance of the glomerular filtration barrier.

Glomerular epithelial cells contribute significantly to the hydraulic and macromolecular permeability properties of the glomerulus. Because of their location as the terminal element in the filtration barrier and their elaborate cytoskeleton, they are likely to participate in the regulation of filtration. In disease, alterations of the glomerular epithelial cells may lead to simplification and retraction of foot processes, resulting in a decreased density of slit diaphragms and decreased by hydraulic conductivity. In addition, denudation of epithelial cells from the basement membrane results in increased macromolecular permeability at those sites and accounts for much of the proteinuria in a variety of types of renal disease.

Animals↗
PubMed1986

The absence of an arterial pressure effect on filtration by perfused glomeruli of the hagfish, Eptatretus stouti (Lockington).

Single renal corpuscles of hagfish were perfused with a Ringer solution containing Ficoll 70 to simulate the colloid osmotic pressure of hagfish plasma. Simultaneous measurements were made of single glomerulus filtration rate (SGFR), perfusion pressure and the pressure in a vessel of the renal vasculature. The results confirm that SGFR is independent of pressure in the glomerular capillaries (PGC). The results also suggest that flow through glomeruli and SGFR are closely linked. Studies of the pressures in glomerular capillaries during periods when the perfusion rate was varied indicate that PGC reflects the area of the active capillaries and the rate of perfusion. Therefore, in the hagfish, PGC appears to be an effect of factors that cause glomerular filtration, not the main cause of that process.

Animals↗
PubMed1989

Creatinine filtration, secretion and excretion during progressive renal disease. Modification of Diet in Renal Disease (MDRD) Study Group.

The Modification of Diet in Renal Disease (MDRD) Study is a multicenter, randomized, controlled trial to determine acceptance, safety, and efficacy of low protein and phosphorus diets in patients with progressive renal disease. During the feasibility phase, 96 patients aged 18 to 75 years, with previously declining reciprocal serum creatinine concentration (1/PCr) and current glomerular filtration rate (GFR) from 7.5 to 80 ml/min/1.73 m2, were randomly assigned four study diets. After randomization, 91 patients were followed for a mean duration of 14.1 months. GFR, 1/PCr and creatinine clearance (CCr) were measured every three months. In an earlier report, we demonstrated relatively weak correlations of rates of change in GFR and 1/PCr during the feasibility phase; the proportion of variability in 1/PCr slopes that was explained by variability in GFR slopes (r2) was only 0.49 to 0.55. In this study, we examined the relationship of GFR and 1/PCr to other determinants of the serum creatinine concentration, including filtration (GFCr), secretion (TSCr), and total renal excretion (UCrV) of creatinine. Our results show that these parameters varied widely among individuals and changed over time. These findings may explain, in part, the relatively weak correlations. These results strengthen our previous suggestion that the rate of change in 1/PCr may not be an accurate index of the rate of change in GFR and raise questions about the validity of conclusions from other studies in which the efficacy of dietary modification in retarding the progression of renal disease was based principally on measurements of 1/PCr.

Adolescent↗
PubMed1988

Cellular proliferation after experimental glaucoma filtration surgery.

We used light microscopic autoradiography to determine the time course of cellular incorporation of tritiated thymidine (a correlate of cell division) following glaucoma filtration surgery in seven eyes of four cynomolgus monkeys with experimental glaucoma. Incorporation of tritiated thymidine was detected as early as 24 hours postoperatively. Peak incorporation occurred five days postoperatively and had returned to baseline levels by day 11. Cells incorporating tritiated thymidine included keratocytes, episcleral cells, corneal and capillary endothelial cells, and conjunctival and corneal epithelial cells. Transmission electron microscopy was correlated with the autoradiographic results to demonstrate that fibroblasts were dividing on the corneoscleral margin. These findings have potential clinical implications for the use of antiproliferative agents after filtration surgery.

Animals↗
PubMed1999

Controlled shear filtration: A novel technique for animal cell separation.

A novel rotary microfiltration technique specifically suited for the separation of animal cells has been developed. The concept allows the independent adjustment of wall shear stress, transmembrane pressure, and residence time, allowing straightforward optimization of the microfiltration process. By using a smooth, conically shaped rotor, it is possible to establish a controlled shear field in which animal cells experience a significant hydrodynamic lift away from the membrane surface. It is shown in preliminary experiments that shear-induced cell-rupture speeds up membrane clogging and that cell debris poses the most significant problem in harvesting of BHK cell cultures by dynamic microfiltration. However, a threshold value of shear stability exists which depends on the frequency of passing the shear field, the residence time in the shear field, as well as on cell status. By operating close to this threshold value, cell viability can be maintained while concentration polarization is efficiently minimized. By applying this concept, it is possible to attain flux rates several times higher compared to conventional crossflow filtration. Controlled shear filtration (CSF) can be used for batch harvesting as well as for cell retention in high cell density systems. In batch harvesting of hIL-2 from rBHK cell culture, a constant flux rate of 290 L h-1 m-2 has been adjusted without indication of membrane clogging or fouling.

Animals↗
PubMed1990

Accuracy of creatinine clearance in measuring glomerular filtration rate in patients with systemic lupus erythematosus without clinical evidence of renal disease.

We sought to determine whether creatinine clearance (Ccr) gives an accurate measurement of the glomerular filtration rate in patients with systemic lupus erythematosus (SLE) with no clinical evidence of renal disease. Eighteen such SLE patients underwent measurement of Ccr and 99mtechnetium-DTPA clearance (CDTPA). The mean +/- SD Ccr:CDTPA ratio was 1.12 +/- 0.15 (95% confidence interval 1.04-1.20). These results indicate that Ccr gives an accurate measurement of the glomerular filtration rate in the majority of SLE patients who do not have clinical evidence of renal disease.

Adult↗
PubMed2002

Controlled shear affinity filtration (CSAF): a new technology for integration of cell separation and protein isolation from mammalian cell cultures.

Controlled shear affinity filtration (CSAF) integrates animal cell separation and product isolation in a single unit operation through the use of a specifically designed rotating disk filter with incorporated membrane chromatography column. Because of the decoupling of shear force and pressure generation and the specific hydrodynamics of the system, shear rates can be easily optimized and precisely controlled to maximize filtration performance while viability of the shear sensitive animal cells is maintained. In this study, the general methodology is demonstrated using the integration of Chinese hamster ovary cell separation and isolation of recombinant tissue plasminogen activator (t-PA) as a model example. Direct capture of t-PA from cell culture broth was realized by using custom-made affinity membranes with lysine as a robust, small molecular weight affinity ligand. Small-scale t-PA adsorption experiments, as well as microfiltration experiments, were used to design the integrated CSAF process. A Chinese hamster ovary batch culture was processed with a lab-scale prototype, yielding 86% of the t-PA in the concentrated, particle-free eluate, whereas 95% of the bulk protein was removed. Because the viability of the cells is not significantly affected and high specific flux rates can be achieved, the CSAF technology should also be well suited for continuous perfusion with integrated product isolation. A truly continuous operation could be realized with two systems in tandem configuration.

Animals↗
PubMed1983

Final inline filtration for intravenous infusions: a prospective hospital study.

Phlebitis is the most common complication of intravenous therapy affecting more than 50 per cent of infusions. Particles in or added to infusions have been implicated, hence a filter with pore size of 0.2 micron containing both hydrophobic and hydrophilic elements (Pall Biomedical) has been evaluated. All infusions of likely duration greater than 48 h, set up in a 2-month period at this hospital, were randomized to filter or identical dummy. The endpoints and statistical power of the study were determined at the outset. Of the 226 infusions randomized, 32 failed within 24 h and were excluded leaving 194 of whom 93 had dummy and 101 filter. Only 38 infusions with dummy survived until no longer required compared to 63 infusions with filter (chi 2 = 7.68, P less than 0.01). Analysed by life table, the trend for filtered infusions to survive longer failed to achieve statistical significance, but inline filtration prolonged the phlebitis-free survival of infusions (P less than 0.01). These benefits were most marked in the 49 infusions where antibiotics were administered via the drip site. Inline filtration delays the onset of phlebitis, thus more infusions survive until they are no longer required. This effect is not sufficiently strong to institute an overall hospital policy but filters may be indicated in patients requiring intravenous antibiotics.

Anti-Bacterial Agents↗