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PubMed2003

A bone fluid flow hypothesis for muscle pump-driven capillary filtration: II. Proposed role for exercise in erodible scaffold implant incorporation.

A model is presented for enhancement of fluid flow through bone matrix and any porous tissue engineering scaffold implanted within it. The mechanism of enhancement is the skeletal muscle pump in compartments adjacent to the bone. Pressure waves from muscle pump contractions aided by increased blood pressure during exercise coupled with temporary occlusion of arteries leading to and veins from the bone, increase hydraulic pressure in cortical bone capillaries so as to amplify capillary filtration. It is proposed that capillary filtration increase is sufficiently convective to contribute to bone fluid flow and associated percolation through tissue engineered scaffold matrix implants. Importance of this contribution is its relative role in maintaining seeded cells in bioreactor scaffolds. Validation of the hypothesis starts at a minimum level of demonstrating that capillary filtration is convective. At a maximum level confirmation of the hypothesis requires demonstration that capillary filtration-based interstitial flow is sufficient to stimulate not only host bone cells (as proposed in part I of the hypothesis) but bioreactor-seeded cells as well. Preliminary data is presented supporting the prediction that skeletal muscle contraction generates convective capillary filtration.

Animals↗
PubMed2002

Effect of seminal plasma concentration and various extenders on postthaw motility and glass wool-Sephadex filtration of cryopreserved stallion semen.

OBJECTIVE: To compare the effect of semen extender and seminal plasma on postthaw motility and filtration through a glass wool-Sephadex (GWS) filter for frozen stallion semen. SAMPLE POPULATION: 7 stallions from which we collected > or = 3 ejaculates/stallion. PROCEDURES: 4 experiments were conducted to evaluate postthaw quality of frozen stallion semen. Kenney extender was compared with glucose-EDTA extender by use of various dilution rates that resulted in differing concentrations of seminal plasma. Stallions known to produce semen with poor postthaw quality were used to investigate whether a particular extender or dilution rate could improve ability of such semen to survive freeze-thaw procedures. RESULTS: Use of Kenney extender as the centrifugation extender significantly improved postthaw motility and GWS filtration, compared with glucose-EDTA. Extending semen at a dilution of 1:3 was significantly better than 1:1 for both motility and GWS filtration. In addition, including seminal plasma at a concentration of 5% in the cryopreserved semen resulted in significantly higher yield of spermatozoa after GWS filtration, compared with complete removal of SP or use of seminal plasma at 25%. Lastly, semen with poor postthaw quality had significantly improved postthaw quality in regard to motility and GWS filtration when semen was frozen with seminal plasma at a concentration of 5%, compared with semen frozen with seminal plasma at a concentration of 25%. CONCLUSIONS AND CLINICAL RELEVANCE: Use of Kenney extender at a high dilution (> or = 1:3) immediately after collection of semen can improve postthaw quality of frozen stallion semen.

Animals↗
PubMed2000

Enhanced short-term plasmid transfection of filtration surgery tissues.

PURPOSE: To quantify and localize plasmid transfection of filtration surgery tissues using two delivery techniques. METHODS: Full-thickness filtering procedures were performed on eyes of New Zealand albino rabbits. In 10 eyes, naked plasmid DNA in saline was either injected beneath Tenon's capsule at the filtration site or absorbed into a collagen shield that was then placed external to the sclerostomy and under the Tenon's capsule. Forty-eight hours after surgery, levels of the reporter gene, chloramphenicol acetyltransferase (CAT) were measured in samples of ocular tissues. In two additional eyes, the ss-galactosidase (ss-GAL:) reporter gene expression was localized histologically. RESULTS: Injection of plasmid DNA in saline vehicle into the filtration bleb produced readily detectable CAT activity in bleb tissue (conjunctiva, Tenon's capsule, and sclera) whereas CAT activity was nearly undetectable in samples of the cornea, iris-ciliary body, and tissues located opposite the bleb site. Delivery of the plasmid DNA into the bleb through a collagen shield increased CAT activity 30-fold over injection of plasmid in saline (2711 +/- 567 mU/mg versus 92 +/- 38 mU/mg). ss-Gal activity was imaged only in the region of the bleb, and microscopic examination showed ss-Gal activity localized to Tenon's capsule fibroblasts, with minimal ss-Gal activity observed in inflammatory cells or scleral fibroblasts. CONCLUSIONS: Transfection of filtration tissues is enhanced by absorption of naked DNA into a collagen shield. Furthermore, transfection is localized to the fibroblasts and inflammatory cells of the filtration bleb site. Gene therapy using naked plasmid DNA and a simple collagen shield delivery vehicle may be useful for regulating wound healing after glaucoma surgery.

Animals↗
PubMed2001

Glaucoma filtration surgery using amniotic membrane transplantation.

PURPOSE: To investigate the potential use of amniotic membrane transplantation (AMT) in the construction of glaucoma filtering blebs. METHODS: Twenty-four albino rabbits underwent glaucoma filtration surgery in one eye. In alternate cases, the conjunctival flap was replaced with AMT. Postoperative examination data were grouped into three time points. Six animals with AMT and six filtration surgery-controls were euthanatized at each of two postoperative time points, and tissue was obtained for histologic examination. Conjunctival biopsies were explanted for estimation of fibroblast outgrowth. RESULTS: Bleb formation was observed in all eyes, and amniotic membranes were epithelialized after 11.2 +/- 2.48 (mean +/- SD) days. Throughout the study IOPs were significantly lower in operated than unoperated fellow eyes. Between postoperative days 11 and 16 (the middle time point), the percentage IOP reduction in AMT eyes was significantly greater than in filtration surgery controls (P = 0.014), though not at other time points. Filtration surgery survival was significantly longer in the AMT group (22.3 +/- 3.8 days; mean +/- SE) than in "No AMT" controls (14.0 +/- 1.6 days; P = 0.035). In tissue culture, significantly less fibroblast outgrowth occurred from AMT explants when compared with unoperated conjunctiva (P = 0.01) between postoperative days 3 and 9 (the early time point). Amniotic membrane transplants were intact on histologic examination after 14 days but were associated with considerable granulomatous inflammation. After 36 days, the ocular surfaces remained clinically intact, but lysis of AMT was noted histologically. CONCLUSIONS: AMT exhibits potential as an alternative tissue to conjunctiva in the construction of glaucoma filtration blebs. The healing response as demonstrated by fibroblast outgrowth is retarded when compared with conventional conjunctival closure. The improvement in bleb survival must be weighed against the potential for complications related to delayed healing. In rabbits, human amniotic membrane elicited a late xenograft reaction, leading to granulomatous inflammation and dissolution of the membrane.

Amnion↗
PubMed1992

Complications and management of the filtration bleb.

Filtration surgery is the commonest operation performed for closed angle or open angle glaucoma when medical treatment or laser trabeculoplasty has failed to control the intraocular pressure. It is characterized by the formation of an artificial drainage fistula between the anterior chamber and subconjunctival space. The successful operation is evidenced by the appearance of a subconjunctival filtration bleb which in turn depends on the patency of this pathway. Despite numerous modification, the procedure trabeculectomy first described by Sugar in 1961 and later on popularized by Watson and Cairns in 1968 is the most popular filtration surgery performed nowadays. It is a safe, relatively easy operation which carries a success rate of around 76% to 84% with a small complication rate. Repeat filtration surgery, however, is often less successful, making a successful initial surgery critically important. A successful outcome of filtration surgery can be enhanced by preoperative preparation, meticulous technique with modification for individual case, and early identification and prompt treatment of the complications arisen.

Anterior Chamber↗
PubMed1955

SEROLOGICAL activity of various fractions of culture filtrates of the tubercle bacillus.

As culture filtrates of Mycobacterium tuberculosis have been shown by numerous workers to be antigenically heterogeneous, a series of experiments has been started to identify some of the different antigens likely to be useful in laboratory tests for measuring the antibodies in human blood. The work involves the fractionation of concentrated culture filtrates by various chemical procedures, the chemical analysis of the fractions, and their subsequent testing and cross-testing with various serological procedures.A number of fractions made from filtrates of heated and unheated cultures have been tested for activity in the Middlebrook-Dubos haemagglutination test. As might be expected, the fractions were found to vary in potency, some showing at least a thousand times more erythrocyte-sensitizing activity than others. Cross-inhibition tests made with the most active preparations indicated the existence of at least two different substances responsible for sensitizing erythrocytes to agglutination, one being demonstrable only in certain unheated fractions.Antibodies detected with the tannic acid haemagglutination test have a different serological specificity from those detected by the Middlebrook-Dubos test. Different heated fractions gave strong cross-reactions with each other in the tannic acid haemagglutination procedure, and little difference could be seen between them; in contrast, four active fractions from unheated filtrates were distinct from each other, showing very little cross-reaction.Results obtained with another haemagglutination procedure, consisting of agglutination of normal erythrocytes by antiserum-antigen mixtures, showed that this method detected another antigen, not measured in the tannic acid or Middlebrook-Dubos techniques under the conditions of the tests.The present experiments have shown that the culture filtrates and fractions thereof contain a series of distinct antigens or at least characteristic combinations of antigens that differ in serological specificity and in their ability to react in the different tests. Further experiments are necessary to determine whether the serological differences are of any special significance in relation to tuberculous disease or bacterial type specificity.

Antibodies↗
PubMed2004

Effect of aeration on gliotoxin production by Aspergillus fumigatus in its culture filtrate.

Gliotoxin, one of the mycotoxins produced by Aspergillus fumigatus, has various, potent bioactivities. However, it has not been considered to be a toxic (or virulence) factor because of its slow production. The aim of the present study was to investigate the effects of aeration on the cytotoxicity of A. fumigatus culture filtrate, and to determine the optimal condition for the rapid production of gliotoxin from this fungus. Fungal culture filtrates were made in three different containers under various conditions of aeration and O2 concentration. These filtrates were compared in terms of their cytotoxicity on murine macrophages and analyzed by gas chromatography. The culture filtrate showed high cytotoxicity when it was made under highly aerated conditions, but it was significantly less cytotoxic when prepared under non-aerated conditions. The cytotoxic activity became evident within 15 h of culture at 20% O2, when the fungus had already started producing gliotoxin. The culture filtrates also contained some other as yet unidentified substances that might also to some extent contribute to the cytotoxicity. In light of these results, the authors propose that a highly aerated condition is responsible for the rapid production of gliotoxin, and that gliotoxin might play an important role in the respiratory infection by A. fumigatus, with other toxic substances acting additively or synergistically.

Animals↗
PubMed2004

Effect of aeration on gliotoxin production by Aspergillus fumigatus in its culture filtrate.

Gliotoxin, one of the mycotoxins produced by Aspergillus fumigatus, has various, potent bioactivities. However, it has not been considered to be a toxic (or virulence) factor because of its slow production. The aim of the present study was to investigate the effects of aeration on the cytotoxicity of A. fumigatus culture filtrate, and to determine the optimal condition for the rapid production of gliotoxin from this fungus. Fungal culture filtrates were made in three different containers under various conditions of aeration and O2 concentration. These filtrates were compared in terms of their cytotoxicity on murine macrophages and analyzed by gas chromatography. The culture filtrate showed high cytotoxicity when it was made under highly aerated conditions, but it was significantly less cytotoxic when prepared under non-aerated conditions. The cytotoxic activity became evident within 15 h of culture at 20% O2, when the fungus had already started producing gliotoxin. The culture filtrates also contained some other as yet unidentified substances that might also to some extent contribute to the cytotoxicity. In light of these results, the authors propose that a highly aerated condition is responsible for the rapid production of gliotoxin, and that gliotoxin might play an important role in the respiratory infection by A. fumigatus, with other toxic substances acting additively or synergistically.

Aerobiosis↗
PubMedDate not supplied

Determination of high and low molecular weight molecules of icodextrin in plasma and dialysate, using gel filtration chromatography, in peritoneal dialysis patients.

OBJECTIVE: The aim of this study was to apply high performance liquid chromatography (HPLC) with modern gel filtration media to determine high molecular weight (HMW) icodextrin fractions and low molecular weight (LMW) icodextrin metabolites in dialysate and plasma in peritoneal dialysis (PD) patients on treatment with icodextrin, and to explore the potential relationships between these compounds, alpha-amylase activity, and glomerular filtration rate. DESIGN: Retrospective study of dialysate and plasma samples from PD patients. SETTING: Samples were collected at one PD center. PATIENTS: Blood and dialysate samples were obtained from PD patients who were subdivided into three groups: patients using only glucose-based peritoneal dialysis fluid (GPDF; GLU group, n = 23), patients studied after the first long dwell with icodextrin-based peritoneal dialysis fluid (IPDF; 1st ICO group, n = 24), and patients who were regular users of IPDF for the long dwells (ICO group, n = 9). METHODS: LMW icodextrin metabolites [i.e., maltose (G2), maltotriose (G3), maltotetraose (G4), maltopentaose (G5), maltohexaose (G6), and maltoheptaose (G7)] and HMW fractions were determined in plasma and dialysate using two different gel filtration HPLC methods. Enzymatic hydrolysis with amyloglucosidase to glucose yielded the total carbohydrate content and this was used to validate the HPLC results. alpha-Amylase activity was determined using a routine method. RESULTS: The results obtained by gel filtration HPLC yielded values of LMW metabolites and HMW fractions in plasma and dialysate in agreement with results obtained with enzymatic hydrolysis. HMW fractions were not detectable in plasma. Absorption of icodextrin from the peritoneal cavity during the long dwell (10 - 16 hours) was, on average, 39% of the amount instilled. During the long dwell, there was a relative decrease in the dialysate concentration of the largest HMW fractions (>21.4 kDa). Plasma concentration of the LMW icodextrin metabolites G2-G7 was highest in the ICO group (2.65+/-0.54 mg/mL) but also higher in the 1st ICO group (1.97+/-0.57 mg/mL) compared with the GLU group (0.52+/-0.23 mg/mL). Plasma alpha-amylase activity was significantly lower in the 1st ICO group and in the ICO group compared with the GLU group. CONCLUSIONS: Accurate analysis of HMW icodextrin fractions in dialysate and LMW icodextrin metabolites in plasma and dialysate in PD patients can be achieved by gel filtration HPLC with two different columns. This method can be used to study the complex pattern of changes in icodextrin and its metabolites in plasma and dialysate. The finding that HMW icodextrin fractions were not detected in plasma was unexpected, and differs from results of previous studies by other researchers.

Chromatography, High Pressure Liquid↗
PubMed2005

[Intraocular penetration of cefotiam hydrochloride, a kind of cephalosporin after filtration surgery in rabbit eyes].

PURPOSE: In this study, we measured the cefotiam dihydrochloride (CTM) concentration in ocular tissue after filtration surgery in rabbit eyes. METHODS: CTM (20 mg/kg body weight) was administered intravenously 30 min before filtration surgery which was performed by double flap procedure on the right eyes of white rabbits. The aqueous humor and serum were extracted at 10 min after surgery and at 30 min, 60 min, and 120 min. Drug concentration in all of the specimens was measured by high performance liquid chromatography (HP-LC). RESULT: The CTM concentrations of aqueous humor in the nonoperated eyes were 0.44 +/- 0.16(mean +/- standard deviation) microg/ml (n = 4) (40 min after intravenous dosage), 0.36 +/- 0.17microg/ml (n = 4) (60 min after intravenous dosage), 0.38 +/- 0.34, microg/ml(n = 3) (90min after intravenous dosage) and 0.27 +/- 0.10 microg/ml (n = 5) (150 min after intravenous dosage). In contrast, CTM concentration in the aqueous humor of the operated eyes was 2.4 +/- 0.95 microg/ml (n = 4) at 10 min after surgery (40 min after intravenous dosage), 2.11 +/- 1.10 microg/ml (n = 4) at 30 min after surgery (60 min after intravenous dosage), 1.18 +/- 0.78 microg/ml (n = 4) at 60 min after surgery (90 min after intravenous dosage) and 0.47 +/- 0.1 microg/ml (n = 5) at 120 min after surgery (150 min after intravenous dosage). The intraocular penetration of CTM at 10 min and at 120 min after filtration surgery was significantly higher in comparison with the drug concentration in the nonoperated eyes (p < 0.05). CONCLUSION: The intraocular penetration of CTM after filtration surgery was much higher in comparison with the drug concentration in the nonoperated eyes. These results may be useful to predict the intraocular penetration of CTM in human eyes after filtration surgery.

Animals↗
PubMedDate not supplied

Blood viscosity and filtration abnormalities in mixed cryoglobulinemia patients.

Blood, plasma and serum viscosity and blood filtration were investigated in 43 unselected mixed cryoglobulinemia patients. A hyperviscosity syndrome was present in only one patient, and rapidly improved after plasma exchange and cyclophosphamide therapy. A clear-cut increase in blood viscosity was infrequently observed in mixed cryoglobulinemia, although significant differences were present in the plasma and serum viscosity of patients and controls. In contrast, blood filtration was severely impaired in a high percentage of cases (51 and 72% of the values recorded at 37 degrees and 25 degrees C, respectively), and was on the average significantly higher in patients than in controls. Indirect evidence suggests that blood viscosity is at least in part related to cryoglobulins. In 19 patients studied before and after cryoglobulin removal, serum viscosity significantly decreased when the serum was deprived of cryoglobulins. In addition, the cryocrit correlated with all the hemorheological parameters with the exception of blood filtration. The hemorheological findings were compared with multisystemic features of the disease, i.e. liver, renal, lung, neurologic, vascular and funduscopic alterations. The potential clinical relevance of the hemorheological parameters was stressed by the close correlation between blood filtration parameters and serum creatinine. Furthermore, by discriminant analysis, viscosity and blood filtration changes were the serological parameters most significantly associated with the presence of renal, liver and neurological involvement. Thus, hemorheological parameters are frequently abnormal in mixed cryoglobulinemia patients, and seem to play a significant clinical role; they should therefore be included in the work-up of these patients.

Adult↗
PubMed1989

The effects of hypoproteinemia and volume expansion on lung and soft tissue transvascular fluid filtration.

Resuscitation from major trauma or replacement of major operative blood loss frequently results in varying levels of protein depletion and alterations in plasma volume. To assess the importance of these factors on pulmonary and soft tissue transvascular fluid filtration, we compared the effects of hypoproteinemia and plasma volume expansion on the rate of lung and soft tissue transvascular fluid filtration in unanesthetized adult sheep. Ten animals were surgically prepared with chronic lung and soft tissue lymph fistulas. Lung (QL) and soft tissue (Qs) lymph flow rates were used to determine changes in transvascular fluid filtration. Initially, lactated Ringer's solution (LR) was infused to elevate pulmonary arterial wedge pressure of normoproteinemic animals (Norm/LR) 5 mm Hg for 2 1/2 hours. After a plasmapheresis-induced protein depletion of 30% to 35%, similar volume expansions with LR (Hypo/LR) and fresh frozen plasma (Hypo/Plas) were performed. Plasma, lung lymph, and soft tissue lymph oncotic pressures were determined, and transvascular oncotic gradients were calculated. Plasma volume expansion during Hypo/Plas conditions limited (p less than or equal to 0.05, 3 hours after infusion) Qs elevations compared with Hypo/LR expansion. However, there appeared to be no significant advantage with fresh frozen plasma over LR infusion in limiting QL. During fresh frozen plasma infusion, a distinct 10- to 12-hour lag in protein transport into the interstitium was observed in the soft tissue but not the lung microcirculation. The resultant differences in fluid filtration properties were in part the result of significant widening of the oncotic gradient in soft tissue. Plasma protein infusion appeared not to be beneficial over LR in limiting lung transvascular fluid filtration during hypoproteinemic states but significantly decreased soft tissue transvascular fluid flux.

Animals↗
PubMed1981

Filtration versus gravity leukapheresis in febrile granulocytopenic patients: a randomized prospective trial.

Forty-eight patients with fever greater than 38.3 degrees C for at least 24 hr despite broad spectrum antibiotics and an absolute granulocyte count less than 1000/microliter were randomly allocated to 4 days of granulocyte transfusions obtained by leukapheresis using filtration (n = 27) or gravity (n = 21) techniques, the latter permitting simultaneous nonmechanical collection of granulocytes and platelets utilizing hydroxyethyl starch as a sedimenting agent. Patient characteristics and dose of granulocytes obtained from both techniques were similar. Complete response to granulocyte transfusions was established by a reduction in temperature to less than 37.2 degrees C sustained for at least 48 hr after the fourth transfusion with sterilization of cultures where previously positive and diminution of measurable infection when present. This occurred in 6/21 (29%) for gravity leukapheresis and 9/27 (33%) for filtration leukapheresis. An additional group had diminution in temperature and clinical improvement during transfusions (6/21 gravity leukapheresis versus 10/27 filtration leukapheresis). Eighty-six percent of patients transfused with gravity leukapheresis cells were alive at day 20 compared with 81% for filtration leukapheresis cells. Transfusion reactions were comparable. Thus, gravity leukapheresis appears to be as efficacious as filtration leukapheresis for treating granulocytopenic febrile patients, with the added advantages of availability to any blood bank without new equipment, of having platelets as by-products, and of not requiring donor heparinization.

Adolescent↗
PubMed1982

Filtration deformability of rabbit pulmonary macrophage.

Rabbit PAM deformability was evaluated by positive-pressure filtration through Nucleopore membranes of well-specified pore diameter. The PAM filtration method was standardized and was influenced by apparatus variations (pore size, flow rate, cell concentration), environment (temperature, pH, divalent cations, protein concentration), and differences in PAM cell volume. The influence of phagocyte function on filtration deformability was evaluated by exposing PAMs to pharmacologic and physiologic agents with somewhat exclusive influences on phagocyte physiology. Agents that interact with microfilament contractile protein (N-ethylmaleimide, cytochalasin B) altered deformability profoundly, but no effect was observed with agents interacting with microtubules (vinblastine, colchicine). Agents that cause general PAM activation (phorbol myristate acetate) or stimulate chemotaxis (F-Met-Leu-Phe) increased deformability. On the contrary, PAM deformability was not changed by phagocytosis of Staphylococcus aureus or latex beads. Pharmacologic agents that alter PAM adhesion (aspirin, indomethacin, physiologic dose hydrocortisone) or inhibit glycolysis (2-deoxyglucose) had no influence on filtration deformability. Filtration PAM deformability reflects passive whole cell rigidity, which appears to be determined by the state of polymerization of the actin-myosin microfilament complex.

Animals↗
PubMed1995

Characteristics of protective immunity engendered by vaccination of mice with purified culture filtrate protein antigens of Mycobacterium tuberculosis.

In this study highly purified culture filtrate proteins obtained from Mycobacterium tuberculosis strains Erdman and H37Rv were tested for their capacity to stimulate immune T cells in vitro, and to immunize mice in vivo. Analysis of the culture filtrate antigen pool revealed a complex mixture of proteins; after separation of this pool into fractions of defined molecular size using an electrophoretic method, it was found that multiple fractions strongly stimulated interferon-gamma (IFN-gamma) secretion by immune CD4 T cells in vitro. In a further series of experiments mice were given multiple immunizations with the culture filtrate protein pool suspended in emulsions of incomplete Freund's adjuvant. Such mice were as resistant as mice given live bacillus Calmette-Guérin (BCG) vaccine to a low dose aerosol challenge infection with M. tuberculosis, but this resistance waned to low levels by 5 months post-vaccination. Furthermore, experiments using the filtrate antigens to boost or augment immunity induced by the BCG vaccination itself were unsuccessful. These data therefore support the hypothesis that the culture filtrate proteins of M. tuberculosis contain multiple antigens that are strongly recognized by T cells acquired during the initial expression of protective immunity to tuberculosis. Conventional immunization with these purified protein antigens can engender a strong degree of protective immunity, but this immunity is apparently not sustained at the same level as that induced by the live vaccine, perhaps suggesting a lack of suitable stimulation of memory immunity.

Animals↗
PubMed1995

Hyperviscosity syndrome: efficacy and comparison of plasma exchange by plasma separation and cascade filtration in patients with immunocytoma of Waldenström's type.

The hyperviscosity syndrome is a common problem in patients suffering from IgM paraproteinemia. In this situation cytotoxic chemotherapy alone is insufficient and additional plasma therapy is required. Until recently, conventional plasma exchange was the only plasma therapy available. While this method has proven its efficacy, it eliminates proteins unselectively. Cascade filtration, on the other hand, has been established to remove proteins as a function of their size offering the prospect of a highly selective withdrawal of macromolecules. In the work presented, the efficacy of conventional plasma exchange and cascade filtration was evaluated performing both techniques at random in cases of hyperviscosity syndrome due to immunocytoma of Waldenström's type (n = 11/group). In these patients, conventional plasma exchange decreased plasma viscosity by 48%; cascade filtration was less effective (26%), correlating with a smaller decrease of IgM (conventional plasma exchange 42% vs cascade filtration 27%). The profile of other plasma proteins studied did not change significantly with either treatment. Furthermore, we observed no differences regarding serious side-effects. In conclusion, we could not demonstrate a superior effect of cascade filtration as compared to conventional plasma exchange in the treatment of hyperviscosity syndrome.

Aged↗
PubMed1993

Culture filtrates and whole heat-killed Candida albicans stimulate human monocytes to release interleukin-6.

The release of interleukin-6 (IL-6) by human monocytes upon stimulation with culture filtrates and heat-killed Candida albicans cells was studied. Two strains of C. albicans (a wild strain CA3 and an agerminative mutant CA2) were cultured overnight at 28 degrees C in complete medium, and 10(6) cells/ml were either filtered at different time points (6, 12, 18, 24, 30 hours) or heat-killed. C. albicans preparations were then added to monolayers of monocytes isolated from healthy donors and incubated at 37 degrees C in 5% CO2 atmosphere. Cell culture supernatants were collected at different time points (every 6 hrs for 30 hrs), and IL-6 content was then measured by immunometric assay. Monocytes stimulated with heat-killed C. albicans cells released IL-6 in the supernatants with values ranging from 59 to 460 pg/ml, that peaked at 24 hrs of incubation. Using heat-killed whole cells of C. albicans no major differences were observed between the two strains used in their capacity to induce IL-6. Culture filtrates also stimulated monocytes to release IL-6 and maximal cytokine levels were observed when the monocytes were triggered with filtrates from yeasts cultured for 24 hours. CA2 filtrate induced IL-6 levels to an extent significantly higher than did CA3 filtrate. These data add further evidence to the immunomodulatory properties possessed by structures of C. albicans.

Candida albicans↗
PubMedDate not supplied

Mathematical model of the filtration in the vascular network of the ophidian glomerulus.

The present work is a mathematical model of the fluid filtration in the glomerular network occurring in snakes. The model is based on the differential form of Starling's hypothesis and takes into account the angioarchitecture of the network and the behaviour on the microrheology of blood with nucleated red cells. The model predicts the hemodynamics and the transvascular fluxes in each vascular segment within the network. The model is applied to a vascular network of the glomerulus of the garter snake. A value of 0.593 microns/(s.mmHg) was determined for the hydraulic conductivity of the glomerular capillaries using the geometrical data of the network together with experimental data for the pressures and the blood flow rate reported in the literature. The analysis shows that the local filtration rates cover a wide range. In some of the vascular segments, the filtration leads to such a high increase in colloid-osmotic pressure that the level of the transvascular hydrostatic pressure difference is reached. Mathematical simulations of the variation of the glomerular blood flow rate due to vasoactivity of preglomerular arterioles show the effect on the filtration rate and the hemorheologic parameters.

Animals↗