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At least 1,045 records · Page 58Linked to original sources
PubMed2001

Risk factors for late-onset infection following glaucoma filtration surgery.

OBJECTIVE: To determine the risk factors for late-onset infection following glaucoma filtration surgery. METHODS: We performed a case-control study comparing 131 cases of late-onset infection collected from 27 surgeons at 10 centers with 500 controls matched for date of surgery and surgeon. The criterion for the presence of infection was severe anterior chamber reaction occurring later than 4 weeks after surgery. An opaque bleb and positive culture results were not required for diagnosis. Risk factors were identified by univariate and multivariate logistic regression analyses. RESULTS: Some of the risk factors that were statistically significant in the multivariate model after adjusting for age, race, and sex were (1) performance of a full-thickness rather than a guarded procedure (risk ratio [RR], 13.1; 95% confidence interval [CI], 2.12-80.9), (2) filtration surgery performed without concurrent cataract surgery (RR, 2.25; 95% CI, 1.24-4.08), (3) use of mitomycin (RR, 2.48; 95% CI, 1.06-5.83), (4) intermittent use of antibiotics after surgery (RR, 2.10; 95% CI, 1.09-4.02), and (5) continuous use of antibiotics after surgery (RR, 5.94; 95% CI, 2.09-16.9). CONCLUSIONS: Eyes undergoing full-thickness procedures or filtration surgery without cataract extraction are at increased risk for late infection. Intraoperative mitomycin and episodic or continuous antibiotic use after the postoperative period are associated with an increased risk of infection.

Aged↗
PubMed2002

Adenovirus-mediated gene therapy using human p21WAF-1/Cip-1 to prevent wound healing in a rabbit model of glaucoma filtration surgery.

OBJECTIVE: To determine if adenovirus-mediated p21(WAF-1/Cip-1) (p21) gene therapy can prevent fibroproliferation and wound healing in a rabbit model of glaucoma filtration surgery. METHODS: In vitro studies were performed using rabbit Tenon fibroblasts harvested from fresh tissue. In vivo studies were conducted in New Zealand white rabbits. A full-thickness sclerotomy was performed under a limbal-based conjunctival flap. Reagents tested included a replication-deficient recombinant adenovirus containing the human p21 gene (rAd.p21); the nonspecific marker gene for green fluorescent protein or beta-galactosidase; mitomycin, 0.5 mg/mL; and balanced saline solution. Each treatment was applied episclerally for 5 minutes before the sclerotomy using a soaked cellulose sponge placed under the surgically created conjunctival flap. Independent experiments were conducted to (1) monitor changes in intraocular pressure during a 30-day period after treatment and examine surgical site histological features, (2) examine changes in bleb morphologic features over 30 days, (3) determine outflow facility 14 days after treatment, and (4) examine the localization and persistence of rAd.p21 expression between 3 and 60 days after treatment. RESULTS: Treatment of Tenon fibroblasts with rAd.p21 resulted in a dose-dependent inhibition of DNA synthesis and cell growth in vitro. In vivo, rAd.p21 inhibited wound healing and fibroproliferation after filtration surgery, comparably to mitomycin. Mitomycin caused notable thinning of the bleb wall. In addition, 2 of the 5 mitomycin-treated eyes exhibited an abscess with hypopyon and hyalitis 30 days after surgery, which was not observed in any of the rAd.p21-treated eyes. None of the treatments resulted in a significantly sustained decrease in intraocular pressure during the 30-day period, although mitomycin treatment resulted in a significant (P =.02) increase in outflow facility 2 weeks after surgery in separate animals. Mitomycin- and rAd.p21-treated eyes had functioning blebs at the end of the experiment based on slitlamp examination. CONCLUSIONS: Mitomycin and rAd.p21 were effective in preventing fibroproliferation and wound healing in a rabbit model of glaucoma surgery. Mitomycin treatment increased outflow facility in normal-pressure eyes. CLINICAL RELEVANCE: Gene therapy with rAd.p21 may provide an effective antiproliferative for glaucoma filtration surgery, without the complications associated with mitomycin.

Adenoviridae↗
PubMed1989

The effect of anterior chamber depth on endothelial cell count after filtration surgery.

Eighteen patients undergoing glaucoma filtration surgery underwent specular microscopic examination 1 day prior to surgery and 4 to 6 months after surgery. Patients were evaluated postoperatively for the presence of iridocorneal or lenticular-corneal touch, anterior chamber depth, and inflammation. Ten eyes that maintained their anterior chamber following glaucoma filtration surgery did not have a significant decrease in corneal endothelial cell density. However, eight eyes that developed a shallow anterior chamber with iridocorneal touch had a mean (+/- SD) decrease of 265 +/- 185 cells (12.4%) peripherally and 250 +/- 243 cells (11.6%) centrally in corneal endothelial cell count. None of the patients with iridocorneal touch developed corneal edema after a mean follow-up of 44.4 +/- 18.0 months. Iridocorneal touch after glaucoma filtration surgery is associated with loss of endothelial cells yet appears to be well tolerated by the cornea.

Aged↗
PubMed1990

Ascorbic acid is cytotoxic to dividing human Tenon's capsule fibroblasts. A possible contributing factor in glaucoma filtration surgery success.

Successful glaucoma filtration surgery depends on the incomplete healing of the surgical wound, with formation of a filtration bleb. In most other tissues, however, complete healing is the rule. I have explored the possibility that the high concentration of ascorbic acid normally present in aqueous humor inhibits wound healing after filtration surgery. At the concentration normally present in aqueous humor (1.1 mmol/L), ascorbic acid decreased the plating efficiency of cell suspensions of human Tenon's capsule fibroblasts by a mean (+/- SD) of 40% +/- 10%. When added to low-density monolayer cultures of fibroblasts, ascorbic acid decreased the cell number by 90% +/- 5%, an effect that was completely prevented by catalase. When added to confluent cultures, the cell number was decreased by only 14% +/- 2%. If ascorbic acid has similar effects on fibroblasts in vivo, it may contribute to the incomplete wound healing that characterizes successful glaucoma surgery.

Ascorbic Acid↗
PubMed1996

Functional morphology of the glomerular filtration barrier of Gallus gallus.

The anionic charge barrier and the endothelial and epithelial pore sizes on the glomerular filtration barrier (GFB) were examined in white leghorn chickens (Gallus gallus). Ruthenium red was used to stain anionic charge sites on the GFB. The tissue was treated by normal dehydration and freeze substitution dehydration for transmission electron microscopy (TEM). In addition, the basal lamina was isolated for study. The results of our study indicate that G. gallus possess a thick, negatively charged glycocalyx surrounding the podocytes and slit diaphragm and on the endothelium. However, in all cases, little anionic charge is present in the basal lamina. The pores on the endothelium are elliptical and have mean dimensions of 148 x 110 nm. This is in contrast to mammals, which have smaller, round pores. The epithelial pores in G. gallus measure approximately 35 nm in length, approximately 4 times larger than those found in mammals. These results indicate that the avian glomerulus may allow the filtration of larger molecules from the plasma than occurs in mammals and that the charge on the molecule may not be as restrictive a filtration characteristic as in mammals.

Animals↗
PubMedDate not supplied

Partitioning of flunitrazepam into model membranes studied by temperature controlled gel filtration chromatography.

The use of gel filtration chromatography with Sephadex as a separation medium was used in order to study flunitrazepam (FNTZ) partitioning into artificial model membranes consisting of dipalmitoyl-phosphatidylcholine (dpPC) vesicles, under controlled temperature conditions. In this system two phenomena are taking place simultaneously: the ligand-liposome interaction and the lipid self-aggregation to form the liposome. The liposome-FNTZ interaction was evidenced by the non-enantiography of the first derivative of FNTZ elution peak in frontal chromatography through Sephadex G-75. On the other hand, the presence of FNTZ reduced liposomes mean size and increased their size dispersion as evidenced by molecular filtration through Sephadex G-200. The dpPC-buffer FNTZ partition coefficient determined in zonal chromatography through Sephadex G-10 increased about 33% when the temperature rose above the temperature of dpPC transition from the liquid crystalline to the fluid phase. Gel filtration chromatography seems a suitable technique to study lipid liposome-FNTZ interactions at a qualitative level. In addition, this technique has the advantage over other methods of giving the possibility of observing the mutual effects exerted between the drug and the self-aggregating structure.

Chromatography, Gel↗
PubMed2002

Electro-membrane filtration for the selective isolation of bioactive peptides from an alpha(s2)-casein hydrolysate.

For the isolation of the ingredients required for functional foods and nutraceuticals generally membrane filtration has too low a selectivity and chromatography is (too) expensive. Electro-membrane filtration (EMF) seems to be a breakthrough technology for the isolation of charged nutraceutical ingredients from natural sources. EMF combines the separation mechanisms of membrane filtration and electrophoresis. In this study, positively charged peptides with antimicrobial activity were isolated from an alpha(s2)-casein hydrolysate using batch-wise EMF. alpha(s2)-Casein f(183-207), a peptide with strong antimicrobial activity, predominated in the isolated product and was enriched from 7.5% of the total protein components in the feed to 25% in the permeate product. With conventional membrane diafiltration using the same membrane (GR60PP), isolation of this and other charged bioactive peptides could not be achieved. The economics of EMF are mainly governed by the energy costs and the capital investment, which is affected by the flux of the desired peptide. A maximum average transport rate of alpha(s2)-casein f(183-207) during batch-wise EMF of 1.2 g/m2. h was achieved. Results indicate that an increase in the hydrolysate (feed) concentration, the applied potential difference and the conductivity of the permeate and electrode solutions, and a reduction in the conductivity of the feed result in a higher transport rate of alpha(s2)-casein f(183-207). This is in line with the expectation that the transport rate is improved when the concentration, the electrical field strength, or the electrophoretic mobility is increased, provided that the electrophoretic transport predominates. The expected energy consumption of the EMF process per gram of peptide transported was reduced by approximately 50% by applying a low overall potential difference and by processing desalinated hydrolysate. Considerable improvements in transport rate, energy efficiency, and process economics seem to be attainable by additional optimization of the process parameters and the EMF module design.

Antimicrobial Cationic Peptides↗
PubMedDate not supplied

High performance gel filtration using monodisperse highly cross-linked agarose as a one-step system for mucin purification.

High performance gel filtration on monodisperse cross-linked agarose (Superose 6) has been assessed as a system for purification of mucus glycoproteins. Comparison with the conventional two-step purification of mucus glycoprotein by Sepharose CL4B gel filtration followed by caesium chloride density gradient centrifugation shows that purification by high performance gel filtration is at least as thorough, yielding mucin that is free from non-mucin glycoproteins as defined by buoyant density, mobility on sodium dodecyl sulphate-polyacrylamide gel electrophoresis and absence of Concanavalin A binding (mannose-containing) material. This technique allows mucus glycoprotein to be purified from lyophilized crude mucin in 120 min compared with approximately 72 h using the conventional techniques. This makes the comparative study of mucus glycoprotein changes in disease states much more feasible.

Cesium↗
PubMed2001

Improvement of macular function by membrane differential filtration in diabetic retinopathy.

BACKGROUND: Alterations of blood rheology are assumed to substantially contribute to the pathogenesis of diabetic retinopathy. Membrane differential filtration (MDF) is an extracorporeal treatment which is able to optimize rheological parameters by eliminating high molecular weight proteins and lipoproteins from the blood. The present study was designed to investigate the effects of repetitive MDF on visual function in diabetic retinopathy. METHODS: 11 patients (11 eyes) with nonproliferative or inactive proliferative diabetic retinopathy underwent three treatment cycles during a mean period of 18 weeks. The best corrected visual acuity served as the main parameter of the study. The measurement of visual acuity, visual field, biochemical and rheological parameters was carried out 24 hours pre and post each treatment cycle and at follow up. The mean follow up time was 9 weeks during the post treatment period. RESULTS: Compared to baseline examination the visual acuity improved stepwise by a mean value of 1.4 lines (p = 0.02) after the last treatment and remained stable at follow up (1.3 lines, p < 0.001). The mean defect of the visual field was reduced by 2.8 dB (p = 0.13) after the treatment period and by 2.5 dB (p = 0.016) at follow up, respectively. CONCLUSIONS: Repetitive treatment with membrane differential filtration is able to improve visual function in patients with diabetic retinopathy. The present study suggests that repetitive membrane differential filtration treatment could be a useful adjunct along with laser treatment to influence the clinical course of diabetic maculopathy.

Blood Proteins↗
PubMed2005

Effective poxvirus removal by sterile filtration during manufacture of plasma derivatives.

As a consequence of the September 2001 terrorist events, programs to protect against further such acts including potentially the use of biological warfare agents have been launched in the USA and elsewhere. As part of these initiatives, Vaccinia virus was procured for the pre-emptive vaccination of key personnel against smallpox as well as population-wide protection after an eventual exposure. The introduction of this live virus into a population at a relatively large scale represents a theoretical challenge for the safety of the blood supply, and potentially for plasma for fractionation. To strengthen further the demonstration of safety margins for plasma derived products against Vaccinia virus, the capacity of sterile filtration procedures to remove the virus was investigated. An infectivity assay for the Vaccinia virus strain which represents the majority of smallpox vaccine stocks available currently was used to investigate the potential removal of this virus by sterile filtration processes during the manufacture of plasma derivatives. Vaccinia virus behaves as predicted based on its size, i.e., an artificially added virus load is removed about 10,000-fold by the sterile filtration procedures tested. As the current investigation covered a range of different protein concentrations, filter materials and filters from different manufacturers, the results obtained are considered to be widely applicable. The current investigation supports further the high safety margins of plasma derivatives against any potential Vaccinia virus content of plasma for fractionation. As the large size is a general feature of Orthopox viruses, the results would also provide assurance against poxviruses identified more recently, for example, Monkeypox virus.

Animals↗
PubMed2003

Identification of novel proteins in culture filtrates of Mycobacterium bovis bacillus Calmette-Guérin in the isoelectric point range 6-11.

Two-dimensional gel electrophoresis and mass spectrometry were used to identify proteins in the isoelectric point range 6-11 in culture filtrates of Mycobacterium bovis bacillus Calmette-Guérin (BCG). Twelve proteins were identified, three of which had not been described previously. The expression of the identified proteins was comparatively analyzed in culture filtrates of BCG in different growth phases and culture conditions. For some of these proteins, the relative protein abundance in the different culture filtrate preparations was significantly different. The differential expression of the identified proteins is discussed in relation to their putative localization and/or biological function.

Bacterial Proteins↗
PubMed1997

Polymer Dose Effects on Filtration Followed by Expression of Clay Slurries

Filtration followed by expression characteristics of cationic polymer conditioned clay slurries are reported for the first time in this work. As the polymer dosage increases, the resistance to filtration greatly decreases until a specific dose has been reached, where the zeta potential is close to zero. And further increase in polymer dose conversely raises the resistance. The expression data are interpreted by the Terzaghi-Voigt combined model, from which the model parameters are evaluated. The polymer conditioning has only a mild effect on the primary consolidation process but has, however, a considerable influence on secondary consolidation characteristics. When zeta potential changes from negative to positive, both the easiness of creeping of constituent particles within the sludge cake and the fraction of moisture removal by the secondary consolidation attain a maximum. The optimal polymer dose criterion considering the filtration and expression stages separately, or in combination, is

Journal Article↗
PubMed1993

Toxicity and pathology of crude broth filtrate produced by Hirsutella thompsonii var. thompsonii in shake culture.

Metabolic products secreted by the fungal mycelia of Hirsutella thompsonii var. thompsonii (CBS 556.77D) in a defined culture broth in shake culture were tested for toxicity to Galleria mellonella larvae and Drosophila melanogaster adults via injection and per os application, respectively. In addition, the toxic effect of broth filtrate was observed in vitro in a cell line of Bombyx mori. Czapek-Dox broth fortified with 1% yeast extract stimulated more rapid mycelial growth and correspondingly more toxin production in time. At 25-30 degrees C, metabolic toxin(s) was detected in broth via bioassay at about 4-5 days postinoculation when mycelial biomass reached 5 mg/ml (dry wt). At these temperatures, biological activity of the filtrate peaked at about 8-10 days when mycelial growth reached a maximum (10 mg/ml, dry wt). This suggests a positive relationship between toxic metabolite and mycelial production. After 10 days, the toxicity of the filtrate appeared to decline gradually. Pathogenicity symptoms of the metabolites developed slowly in both G. mellonella and D. melanogaster. Early signs of lethargy appeared at 4 days postinjection and cumulative mortality of G. mellonella larvae was low after 1 week; however, the percentage of mortality reached 98-100% after 14 days. At death, G. mellonella larvae displayed small dark spots on a brownish cuticle. Histopathological effects were observed in the larval midgut, malpighian tubules, hypodermis, fat body, hemocytes, muscle, and silk glands. Cellular change consisted of pycnosis of the nucleus and a reduction in cytoplasm density. Highest mortality (78.8%) to adult D. melanogaster occurred after 10 days post-treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1975

Functional structure of the glomerular filtration barrier and the proximal tubuli in the developing foetal and neonatal pig kidney.

1. The detailed anatomy of the structures forming the glomerular filtration barrier and the proximal tubules was studied during development of foetal and neonatal pigs. 2. In the glomerular filtration barrier during ontogenetic development an increased number of fenestrae was noted in the endothelium. The condensation decreased in the glomerular basement membrane and an increase in the widths of the pedicles was observed. 3. The proximal tubular cells revealed a highly specialised organisation with an enlarged cell surface (microvilli) towards the lumen. In the apical part of the cell a zone containing vesicles probably pinched off from the base of the microvilli was observed. At the base of the cell elongated mitochondria and electron dense bodies were found. 4. An increase in the number of vesicles was observed in the proximal tubular cells from piglets receiving colostrum and exhibiting proteinuria. Judging from these results it seems probable that the nephrons are able to function already in the metanephros of the pig foetuses of 4 cm CR-length. 5. The results imply that there was no structural evidence of an immature glomerular filtration barrier being the cause of neonatal proteinuria. On the other hand an enhanced involvement of the cells of the proximal tubules was noted and this is interpreted to be due to the absorption of proteins from the primary urine after onset of colostrum ingestion by the newborn piglet.

Animals↗
PubMed1977

The effect of hydroxyethylrutosides on capillary filtration rate in the lower limb of man.

The rate of capillary filtration in the lower limbs after hydroxyethylrutosides administered in various doses and by different routes was studied in patients with chronic venous insufficiency. Capillary filtration rate decreased immediately after intravenous and from 55 to 85 minutes after oral administration, depending on the dose. The slow-release tablets produced a definite falt in capillary filtration 240 minutes after administration.

Administration, Oral↗
PubMed1981

Microscopical determination of the filtration permeability of the mucosal surface of the goldfish intestinal epithelium.

The rate of shrinkage of the mucosal folds of goldfish intestine in response to mucosal hypertonicity was measured by microscopic means. Because of the geometry of the intestinal folds the rate of shrinkage could be directly related to the loss of volume from the fold through the brush border membranes and tight junctions. Experimentally a wide range of velocities was observed, reflecting the difficulty of rapidly establishing a uniform osmotic gradient at the preparation's mucosal surface. The initial velocity of volume loss provided a measure of the filtration permeability (Pf) of the mucosal surface. From the highest velocities observed the filtration permeability was estimated to be approximately 14 X 10(-3) cm/sec related to the folded mucosal surface and 65 X 10(-3) cm/sec related to the straight serosal surface. Consideration of the experimental errors and unstirred layer effects make it probable that the latter value is still an underestimate of the true Pf. The series barriers of the epithelium cause the total tissue Pf to be less than the Pf of the mucosal surface alone. In addition the Pf measured in the presence of an osmotic gradient may differ substantially from the tissue filtration permeability which exists in the absence of a change in osmolarity.

Animals↗
PubMed1987

Increased synthesis of ajmalicine and catharanthine by cell suspension cultures of Catharanthus roseus in response to fungal culture-filtrates.

The ammonium sulfate-precipitated fraction from mycelia and culture-filtrates and the crude, cell-free culture filtrates from the growth medium of the fungi Chrysosporium palmorum, Eurotium rubrum, Micromucor isabellina, and Pythium aphanidermatum when aseptically added to cell suspensions of Cantharanthus roseus caused a rapid and dramatic increase in indole alkaloid biosynthesis. Up to 400 micrograms/L ajmalicine and 600 micrograms/L catharanthine were detected in C. roseus cell suspension grown in the presence of the M. isabellina fungal culture filtrate for 3 d. Untreated cells produced only trace levels of ajmalicine and catharanthine per liter of cell suspension after 15 d of culture.

Cell Line↗
PubMed1994

Development of high-molar-mass cellobiase complex by spontaneous protein-protein interaction in the culture filtrate of Termitomyces clypeatus.

The 450 kDa cellobiase from Termitomyces clypeatus which migrates as a single band on IEF, PAGE and SDS-PAGE, was found to possess appreciable sucrase activity. The fungus produced sucrase and cellobiase constitutively in different media but with different activity ratios. The kinetics of secretion of the two enzymes was similar under in vivo and in vitro conditions. HPGPLC analysis of the culture filtrates indicated the presence of both sucrase and cellobiase in the same protein fractions of different molar mass, even in the 30-kDa protein fraction. No free sucrase or cellobiase could be detected in the culture filtrates. It was also observed that fractionation of cellobiase by (NH4)2SO4 precipitation was different with different amounts of associated sucrase activity present in the culture filtrate. The (NH4)2SO4-precipitated cellobiase fraction also contained cellobiases in proteins of widely varied molar mass ranges. However, none of the low-molar mass proteins other than the 450-kDa enzyme could be purified, as all low-molar-mass fractions spontaneously aggregated to the 450-kDa enzyme. Hydrophobic chromatography of the (NH4)2SO4-precipitated fractions followed by HPGPLC of the eluted active fraction yielded both cellobiase-free sucrase and a very low sucrase-containing cellobiase fraction. The cellobiase fraction, homogeneous in PAGE, was also a high-molar-mass protein complex dissociating into a number of protein bands on SDS-PAGE.(ABSTRACT TRUNCATED AT 250 WORDS)

Basidiomycota↗