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PubMed1979

Transcapillary passage of albumin, effects of tissue cooling and of increases in filtration and plasma colloid osmotic pressure.

'Initial' clearance of radiolabelled serum albumin was measured in the perfused, maximally vasodilated muscle vascular bed of rat hindquarters during tissue cooling, during increases in filtration and during changes in serum colloid osmotic pressure. Albumin clearance during ordinary serum perfusion at isogravimetry amounted to 0.03 ml/min times 100 g, increasing linearly with filtration rate to some 0.07 ml/min times 100 g at 0.5 ml/min times 100 g of filtration. During cooling from 36 degrees C to 14 degrees C both CFC and initial albumin clearance at isogravimetry decreased some 40%, in due proportion to the increased viscosity of the fluid. Increases of the colloid osmotic pressure of the perfusate correspondingly increased both the isogravimetric capillary pressure and 'initial' albumin clearance during isogravimetry.--It is concluded that even during isogravimetry the transmicrovascular albumin passage is to about 70 per cent due to filtration, and only some 30 per cent of transport at ordinary serum colloid osmotic pressure takes place by diffusion, both events presumably via 'large pores'. There was no evidence that transendothelial vesicular transport should to any significant extent contribute to the passage of albumin from vessels to tissue.

Animals↗
PubMed1983

Effect of chronic sympathetic denervation upon the transcapillary filtration rate induced by venous stasis.

The effect of venous pressure elevation upon capillary filtration rate in the limb was studied in 6 chronically sympathectomized patients. Five healthy subjects served as controls. Volume changes of the forearm or calf were recorded by a strain-gauge plethysmograph. Relative blood flow in subcutaneous and muscle tissue during venous stasis was measured by the local 133Xe washout technique. In the denervated limbs there was a linear relationship between net capillary filtration rate and venous pressure elevation. In the controls a non-linear relationship was seen as venous pressure elevation of 40 mmHg only caused an increase in net filtration rate of about 66% of that expected from a linear relationship. In the denervated limbs of blood flow in muscle and subcutaneous tissue remained constant during venous pressure elevation of more than 30 mmHg whereas in the non-denervated limbs blood flow decreased by about 50% in both tissues. The results suggest that a local sympathetic veno-arteriolar (axon) reflex plays a dominant role for the reduced increase in net capillary filtration during large increases in venous pressure. The local axon reflex may therefore act as an edema protecting factor.

Adult↗
PubMed1995

[Effects of the Prevotella intermedia culture filtrate and short-chain fatty acids on human polymorphonuclear neutrophil functions].

Anaerobes, in particular Prevotella spp., are the predominant bacteria present in mixed respiratory infections. To study the virulence factor of Prevotella intermedia, we examined the effects of the culture filtrate of P. intermedia on the bactericidal activity of human polymorphonuclear neutrophils (PMNs). The culture filtrate significantly inhibited the phagocytic killing and the intracellular killing of Staphylococcus aureus by PMNs (p < 0.05), but the phagocytosis of PMNs was not affected. The boiled culture filtrate also inhibited the phagocytic killing of PMNs (p < 0.05), which suggests that the inhibitory effect may be mediated by heat-stable substances. Succinic and isovaleric acid were mainly detected from the culture filtrate by gas chromatography. The migration of PMNs was significantly inhibited by these short-chain fatty acids (15 mM succinic acid, p < 0.01 and 1 mM isovaleric acid, p < 0.05). The phagocytic killing of PMNs was significantly inhibited by succinic acid (30 mM, p < 0.05) and not by isovaleric acid. Therefore, these inhibitory effects on human PMN functions may be contributed to the virulence of the mixed infections with anaerobes.

Blood Bactericidal Activity↗
PubMed1959

Leukemogenic activity of filtrates from radiation-induced lymphoid tumors of mice.

Cell-free filtrates of x-ray-induced lymphoid tumors of strain C57BL/ Ka mice have elicited, on injection into newborn isologous hosts, a lymphoma incidence of 15 to 19 percent. In control mice of the same subline, the incidence of spontaneous lymphoma is about 1 percent. No leukemogenic activity could be detected in filtrates from thymi harvested at 2 to 32 days following completion of x-ray treatment. Activity was evident at 64 days and was perhaps somewhat greater at 128 days. Serial cell-free passage of filtrates in newborn F(1) hybrid mice resulted in a marked increase in lymphoma incidence (69 percent), coupled with a shortening of the median latency. Supplementary x-irradiation failed to enhance the activity of filtrates after neonatal injection.

Animals↗
PubMed1977

Prelytic damage of red cells in filtrates from peroxidizing microsomes.

When liver microsomes are incubated in the presence of reduced nicotinamide adenine dinucleotide phosphate (NADPH), their constituent lipids undergo peroxidative degeneration. If erythrocytes are present in such a peroxidizing system, they hemolyze. Filtrates obtained by ultrafiltration of peroxidizing microsomal systems were found to have the capacity to produce prelytic damage in red cells. Filtrates obtained from microsomes that had not undergone peroxidative lipid decomposition were inert. The toxic activity in the active filtrates was not due to continuing oxidation of NADPH nor to continuing liver microsomal lipid peroxidation. Neither the chemical identity of the toxic product or products in active filtrates nor the mechanisms involved in the erythrocyte damage are known at this time.

Erythrocyte Membrane↗
PubMed1980

Improved filtration technique for concentrating and harvesting bacteria.

An improved technique is described for the filtrative concentration and harvesting of bacterial cultures. A pleated tangential flow filtration unit containing 1,000 cm of 0.2-mum-pore-size microporous membrane was used to rapidly (30 to 50 min) reduce the volume of 5 liters of bacterial culture of approximately 10 cells per ml to 0.2 to 0.5 liters of concentrated bacterial suspension. The effects of cell concentration, filtration pressure, and tangential flow rate were examined with respect to the rate of concentration and cell viability. Recovery efficiencies were between 60 and 75%, with no apparent impairment of organism viability. Cell concentration exerted the predominant effect on the filtration rate.

Journal Article↗
PubMed1986

Stimulation of tentoxin synthesis by aged-culture filtrates and continued synthesis in the presence of protein inhibitors.

Tentoxin, a cyclic tetrapeptide produced by Alternaria alternata (Fries) Keissler, induces chlorosis in certain seedling plants. It can be extracted from culture filtrates of the fungus. Tentoxin production is stimulated and increased by using a mixture of aged culture filtrates and modified Richards solution. Aged culture filtrates can be obtained from 3-week-old or older cultures of A. alternata in modified Richards solution or Pratts solution. A mixture of aged culture filtrate and fresh medium in the ratio 2:3 gives the maximal enhancement of tentoxin production. This growth system provided us with a model for studying the effects of protein synthesis inhibitors on tentoxin production. Two antibiotics which inhibit protein synthesis at the ribosomal level were tested on growth, protein synthesis, and tentoxin production in A. alternata cultures. Cycloheximide at concentrations of 500 mug/ml or emetine at concentrations of 250 mug/ml did not inhibit tentoxin synthesis, although they stopped mycelial growth and protein synthesis of the fungus at the logarithmic growth stage in the enhancement medium. These results led us to conclude that tentoxin, like certain other bioactive cyclic peptides, is synthesized by a nonribosomal peptide synthesis mechanism.

Journal Article↗
PubMed1974

Fermentation of feedlot waste filtrate by fungi and streptomycetes.

The soluble and dispersed nitrogen and carbon components in the filtrate fraction of cattle feedlot waste are a potential nutrient source from which single-cell protein could be produced for animal feeds. The ability of more than 200 fungi and streptomycetes to grow in this liquid was determined; these included isolates from the waste and associated sources, as well as organisms maintained in the Culture Collection of the Agricultural Research Service in Peoria, Ill. Utilization of waste nutrients was measured by changes in nitrogen content and chemical oxygen demand. Only 20% of the organisms were able to grow appreciably in the filtrate. Of these, dry-weight yields varied from 0.6 to 2.7 g of mycelium per liter; from 21 to 50% of the nitrogen in the filtrates was used during growth, whereas chemical oxygen demand levels diminished from 4 to 60%. In general, streptomycetes isolated from the feedlot used nutrients from the filtrates better than fungi did. Addition of readily available carbon sources such as glucose or whey significantly increased (as much as sixfold) cell yields of selected organisms and promoted better utilization of nitrogen (from two- to threefold); the effect on chemical oxygen demand varied (0 to 33% increase).

Animals↗
PubMed1978

Effects of iron and culture filtrates on killing of Neisseria gonorrhoeae by normal human serum.

Neisseria gonorrhoeae GC9, both colony types T2 and T4, were killed by normal human serum, although populations of colony type T4 were more susceptible. Ferric ammonium citrate prevented the killing of populations of both T2 and T4 colony types. Other iron compounds tested showed no protective effect, nor did ammonium citrate or the divalent cations magnesium or calcium. A filtrate from cultures of an N. gonorrhoeae strain grown in a liquid defined medium showed a similar protective effect in the serum assay. The filtrate appeared to chelate iron, as measured by decreased ability of iron-free transferin to bind iron in the presence of the filtrate. However, the two effects did not appear to be related. Neither ferric ammonium citrate nor the culture filtrate sufficiently inactivated complement to account for protection.

Blood Bactericidal Activity↗
PubMed1971

Immunochemical Studies of Two Cholera Toxin-Containing Standard Culture Filtrate Preparations of Vibrio cholerae.

Two crude toxin preparations of Vibrio cholerae, labeled lot 4493 G (Inaba) and lot 001 (Ogawa), consisting of freeze-dried culture filtrate, were studied with regard to toxicity, precipitinogenicity, and chemical composition. Lot 4493 G contained much more carbohydrate and less protein than lot 001, but both of the preparations contained three precipitinogens which were identical. One of these factors was identified as cholera exotoxin. In addition, both contained a fourth cross-reacting precipitinogen related to lipopolysaccharide. The toxicity of the lots was very similar. The toxin active as permeability factor in the intradermal test, identified completely in comparative double-diffusion analyses with the toxin causing cholera-like symptoms in experimental animals, strongly indicated that the same toxin molecule was active in the two different model systems. The isoelectric point of the toxin was about pH 7, but some toxic activity focused toward a pH of 9. The toxicity was completely retained by a UM-10 membrane (cut at a molecular weight of 10,000), practically retained by a PSED membrane (cut at a molecular weight of 25,000), but not retained by an XM-50 membrane (cut at a molecular weight of 50,000). By gel filtration through agarose, it was possible to separate and purify more than 1,000-fold the toxin from the other, more rapidly filtering three precipitinogens. With lot 4493 G, the toxicity of the agarose gel filtration fractions was restricted to an elution volume similar to that of globular proteins with a molecular weight of 25,000 to 38,000, whereas gel filtration experiments through Sephadex G-75 indicated a size of the toxin corresponding to a molecular weight of about 55,000 to 60,000.

Journal Article↗
PubMed2003

Photodynamic modulation of wound healing in glaucoma filtration surgery.

AIM: To report a clinical pilot study investigating photodynamic therapy (PDT) in combination with glaucoma filtration surgery. BCECF-AM was used as the photosensitising substance. The clinical safety and tolerability of BCECF-AM, and its efficacy in controlling postoperative intraocular pressure (IOP) were assessed. METHODS: Before trabeculectomy (TE), 42 consecutive eyes of 36 glaucoma patients received one subconjunctival injection of 80 micro g BCECF-AM (2,7,-bis- (2-carboxyethyl) -5- (and-6) -carboxy-fluorescein, acetoxymethyl-ester) followed by an intraoperative illumination with blue light (lambda = 450-490 nm) for 8 minutes. Antifibrotic efficacy was established as postoperative IOP reduction of >20% and/or an IOP constantly < 21 mm Hg without antiglaucomatous medication. Follow up of the filtering bleb was documented by slit lamp examination. RESULTS: Eyes had mean 1.1 preoperative surgical interventions (filtration and non-filtration glaucoma surgery). Mean preoperative IOP was 31.6 (SD 9.7) mm Hg. Patients were followed for mean 496 days (range 3.5-31.8 months). Of the 42 eyes, 25 eyes had an IOP decreased to 15.8 (3.4) mm Hg without medication (complete success: 59.5%; p<0.001; t test). Seven eyes showed good IOP reduction < 21 mm Hg under topical antiglaucomatous medication (qualified success: 16.7%). 10 eyes failed because of scarring within 2-67 weeks (23.8%). Clinical follow up examinations revealed no local toxicity, no uveitis, and no endophthalmitis. CONCLUSIONS: This method is a new approach in modulating postoperative wound healing in human eyes undergoing glaucoma filtration surgery. The data of the first human eyes combining TE with PDT underline the clinical safety of this method and its possible potential to prolong bleb survival.

Adult↗
PubMed1992

Comparison of spontaneous ascites filtration and reinfusion with total paracentesis with intravenous albumin infusion in cirrhotic patients with tense ascites.

OBJECTIVE: To compare the effectiveness and safety of spontaneous ascites filtration and reinfusion and total paracentesis plus intravenous albumin infusion in cirrhotic patients with tense ascites. DESIGN: Randomised trial of the two treatments. SETTING: Teaching hospital and district general hospital in Milan. PATIENTS: 45 consecutive cirrhotic patients with recurrent tense ascites and urinary sodium excretion rate less than 20 mmol/day. 35 fulfilled admission criteria and completed the study. 17 received spontaneous ascites filtration and 18 paracentesis plus albumin infusion. MAIN OUTCOME MEASURES: Body weight; urinary volume; serum and urinary electrolyte, serum fibrinogen, and plasma aldosterone concentrations; and plasma renin activity before the procedure and 24 hours and eight days afterwards. RESULTS: Both procedures were effective in all patients. Weight decreased in both groups and showed no substantial increase after eight days. In patients receiving ascites filtration, values decreased significantly (p less than 0.01) after 24 hours for platelet count (mean relative change 0.92; 99% confidence interval 0.86 to 0.98) and serum fibrinogen concentration (0.92; 0.88 to 0.98) but returned to pretreatment values after eight days; no laboratory and clinical signs of disseminated intravascular coagulation were noted. Three patients in this group had fever, which receded spontaneously. One patient in each group had dilutional hyponatraemia. CONCLUSIONS: Spontaneous ascites filtration and reinfusion is an effective treatment for tense ascites. Reinfusion of the patient's concentrated proteins provides savings without compromising safety.

Adult↗
PubMed1982

Autoregulation of intestinal capillary filtration rate.

To determine whether intestinal capillary filtration rate, capillary pressure, or both are autoregulated in the cat ileum, the following parameters were measured under isovolumetric conditions: lymph flow, capillary pressure, capillary filtration coefficient, and lymph and plasma oncotic pressures. Superior mesenteric arterial pressure was reduced in 25-mmHg steps from 125 to 25 mmHg. As arterial pressure was reduced, lymph flow, capillary pressure, and the transcapillary oncotic pressure gradient decreased while the capillary filtration coefficient increased. Over the arterial pressure range of 75-125 mmHg, capillary pressure decreased in a fashion expected from a rigid system; however, capillary pressure was slightly autoregulated at lower arterial pressures. Lymph flow fell proportionately more than capillary pressure over the entire arterial pressure range. The results of this study indicate that intestinal capillary pressure and capillary filtration rate are poorly autoregulated in the cat when arterial pressure is reduced. Changes in interstitial fluid pressure play a major role in preventing interstitial dehydration in the cat ileum when arterial pressure is reduced.

Animals↗
PubMed2004

Onset of pulsatile pressure causes transiently increased filtration through artery wall.

Convective fluid motion through artery walls aids in the transvascular transport of macromolecules. Although many measurements of convective filtration have been reported, they were all obtained under constant transmural pressure. However, arterial pressure in vivo is pulsatile. Therefore, experiments were designed to compare filtration under steady and pulsatile pressure conditions. Rabbit carotid arteries were cannulated and excised from male New Zealand White rabbits anesthetized with pentobarbitol sodium (30 mg/kg i.v. administered). Hydraulic conductance was measured in cannulated excised rabbit carotid arteries at steady pressure. Next, pulsatile pressure trains were applied within the same vessels, and, simultaneously, arterial distension was monitored using Optical coherence tomography (OCT). For each pulse train, the volume of fluid lost through filtration was measured (subtracting volume change due to residual distension) and compared with that predicted from steady pressure measurements. At 60- and 80-mmHg baseline pressures, the experimental filtration volumes were significantly increased compared with those predicted for steady pressure (P < 0.05). OCT demonstrated that the excess fluid volume loss was significantly greater than the volume that would be lost through residual distension (P < 0.05). After 30 s, the magnitude of the excess of fluid loss was reduced. These results suggest that sudden onset of pulsatile pressure may cause changes in arterial interstitial hydration.

Animals↗
PubMed1988

Effect of pulmonary perfusion on lung fluid filtration in young lambs.

To study the effect of pulmonary perfusion on fluid filtration in the newborn lung, we measured pulmonary vascular pressures, cardiac output, lung lymph flow, and concentrations of protein in lymph and plasma of nine healthy, awake lambs, 2-3 wk old, before and during sustained alterations in pulmonary blood flow. A 12% reduction in cardiac output (from partial occlusion of the inferior vena cava) led to a corresponding decrease in lymph flow, consistent with a reduction in net lung fluid filtration. A 20% increase in pulmonary blood flow (from opening an external shunt between the carotid artery and jugular vein) increased lymph flow by approximately 40%, without a significant change in lymph protein concentration. These findings suggest that lung microvascular surface area expanded in response to increased perfusion, with little or no change in filtration pressure. In five lambs, lung microvascular pressure was increased by inflating a balloon catheter in the left atrium to establish full patency of the pulmonary microcirculation. In the presence of left atrial pressure elevation, increased perfusion through the arteriovenous shunt had no significant effect on pulmonary vascular pressures or lymph flow. Thus, in young lambs, modest changes in pulmonary blood flow may affect lung fluid filtration by altering perfused microvascular surface area; this response is inhibited in the presence of left atrial hypertension.

Animals↗
PubMed1984

Fetal whole-body interstitial compliance, vascular compliance, and capillary filtration coefficient.

Fluid movements across the capillary wall were studied in chronically catheterized, near-term fetal sheep. We hemorrhaged 15 fetuses and infused isotonic saline in seven fetuses. The average experimental changes in arterial pressure, venous pressure, and blood volume were then analyzed by using mathematical modeling and parameter optimization techniques to estimate mean values for the average whole-body interstitial and vascular compliances of the fetus and for the average whole-body fetal capillary filtration coefficient. After fetal hemorrhage, interstitial compliance averaged 45 ml X mmHg-1 X kg-1 of fetal weight and vascular compliance averaged 3.0 ml X mmHg-1 X kg-1, whereas the capillary filtration coefficient averaged 0.4 ml X min-1 X mmHg-1 X kg-1. For intravenous saline infusions, interstitial compliance averaged 45 ml X mmHg-1 X kg-1, and vascular compliance averaged 3.5 ml X mmHg-1 X kg-1, whereas the capillary filtration coefficient averaged 0.8 ml X min-1 X mmHg-1 X kg-1. These data suggest that the fetus has a high whole-body interstitial compliance and a high capillary filtration coefficient compared with the adult. In addition, it appears that the fetus has the ability to decrease its vascular compliance and capillary surface area after a fetal hemorrhage.

Animals↗
PubMed1990

Novel determination of filtration coefficient of ovine placenta and intramembranous pathway.

We recently reported that distilled water injected into the amniotic compartment is rapidly absorbed by the fetal blood, which perfuses the fetal membranes and the fetal surface of the placenta, i.e., by the "intramembranous pathway." In the present study, we infused warmed distilled water at 2 ml.min-1.kg estimated fetal wt-1 into the amniotic compartment for 6-8 h in 12 chronically catheterized sheep. A steady state was achieved in amniotic fluid, fetal blood, and maternal blood osmolalities in 5.1 +/- 0.3 (SE) h. During the steady state, all of the infused water must pass to the ewe. Because the amount of water directly crossing the fetal membranes into the maternal circulation was not significantly different from zero (3.3 +/- 5.8% of total), we assumed all water crossed the placenta. The placental filtration coefficient was then calculated during the steady state as the infusion rate divided by the changes in the transplacental osmotic gradient and averaged 0.0260 +/- 0.0055 ml.min-1.mmHg-1.kg fetal wt-1. Attempts to correct this value for placental reflection coefficients less than 1 were unsatisfactory; thus the uncorrected value appears to provide the best estimate of the placental filtration coefficient. Similar calculations yielded a value of 0.00137 +/- 0.00025 ml.min-1.mmHg-1.kg-1 for the filtration coefficient of the intramembranous pathway. Thus this method provides a relatively simple new technique for estimating the filtration coefficient of the ovine placenta and intramembranous pathway under steady-state conditions.

Amnion↗
PubMed2004

New trends in HDF therapies: validity of internal filtration-enhanced hemodialysis.

Internal filtration-enhanced hemodialysis (IFEHD), defined as HD therapy using a dialyzer designed for enhanced internal filtration, seems to be more convenient in comparison with HDF therapies. In this paper, the validity of IFEHD was discussed during an analytical study and experimental studies. As a result, the maximum internal filtration flow rate (Q(IF)) value increased with a smaller inner diameter (D), a longer effective length (L(eff)), and a larger density ratio (DR) value of the hollow fibers. The validity of IFEHD was clarified by an analytical study and experimental studies. Development of a dialyzer with enhanced internal filtration, however, should take account of the patient's safety, and hemolysis and endotoxin invasion form the dialysate to the patient should be avoided.

Equipment Design↗