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Biomedical subjects

M V Dennis

Publications and source records attributed to M V Dennis.

15 recordsLinked to original sources
PubMed1990

Protective qualities of mitochondrial and cytosolic fluorescent dyes against in vitro and in vivo infection by the Tulahuen strain of Trypanosoma cruzi.

This study demonstrates the binding of various fluorescent dyes (3,3' dihexyloxacarbocyanine iodide [DiOC6I], doxycycline [DOTC], rhodamine 123, and merocyanine 540) to infectious and intracellular forms of the Tulahuen strain of Trypanosoma cruzi. These dyes predominantly localize in mitochondria. Following treatment with DiOC6I and DOTC, both irradiated and nonirradiated samples showed dark toxicity to T. cruzi, whereas the other dyes effected toxicity only following irradiation with light. Under in vitro conditions, 91% protection was obtained 96 hr postinfection under dark conditions through the use of 0.573 micrograms/ml of DiOC6I. During in vivo studies, the onset of parasitemia was delayed by 7 days through the use of DiOC6I in ng/ml levels. Host deaths occurred in the infected control group on day 11 postexposure, whereas in the 5.7-ng/ml dye-treated group, no death had occurred after 20 days postexposure. This study demonstrates delay of onset of T. cruzi infections with the use of DiOC6I at concentrations well below the levels toxic to the host.

Animals↗
PubMed1989

Protection of NIH 3T3 cells from infection by trypomastigotes and sphaeromastigotes of Trypanosoma cruzi, Telahuen strain, by porphyrins in the presence and absence of light (630 and 690 nm).

The light and dark toxicities of naturally occurring and synthesized porphyrins were investigated for their potential to protect NIH 3T3 cells from infection with mammalian tissue culture-derived trypomastigotes of Trypanosoma cruzi. The fluorescent nucleic acid dye Hoechst 33342 was employed to trace T. cruzi intracellular development following porphyrin exposure with and without irradiation. The synthetic porphyrins investigated included isomers A and B of mono- and diacid benzoporphyrin (BPD-MA, BPD-DA, BPD-MB, and BPD-DB). derivatives of naturally occurring hematoporphyrin dihematoporphyrin ether (DHE), and hydroxyethylvinyl deuteroporphyrin (HEVD). These porphyrins provided positive protection following irradiation with light Protection also was obtained due to dark toxicity phenomena. HEVD at a concentration of 1.0 micrograms/ml followed by irradiation of 20 J/cm2 of light at 630 nm provided 90% protection, whereas BPD-MA and BPD-MB provided greater than 85% protection using irradiation at 690 nm. Dark protection was greatest at 1.0 micrograms/ml with the BPD (55-70%), but HEVD provided the greatest toxicity (89%) at a concentration of 10 micrograms/ml. Further investigations are in progress to find methods to increase the protection obtained and to determine the mechanism(s) involved in protection.

Animals↗
PubMed1984

Secreted glycoproteins of human kidney tumour cells contain sulphated complex-type oligosaccharides.

Human kidney tumour cells in culture incorporated [3H]glucosamine and 35SO4 into glycoprotein products, which were secreted into the culture medium. The effects of sodium butyrate, a known differentiation-inducing agent, on the production of these sulphated glycoproteins were studied. Cells were cultured in the absence or presence of butyrate (2 mM) in serum-containing medium, for various times, and the labelled glycoproteins were partially purified by DEAE-cellulose chromatography. Treatment of these cells with butyrate resulted in an increase in the synthesis of secreted [3H]glucosamine- and 35SO4-labelled glycoproteins over several days of culture. This same increase in levels of 35SO4 incorporation was not observed with B16 melanoma cells. Sodium dodecyl sulphate (SDS)/polyacrylamide gel electrophoresis revealed that five major glycoproteins labelled with [3H]glucosamine also were labelled with 35SO4. The major secreted glycoproteins from cells cultured in the absence or presence of butyrate over a 3-day period were similar by SDS/polyacrylamide gel electrophoresis. Analyses of Pronase-derived glycopeptides indicated that these secreted 3H/35S-labelled glycoproteins contained sulphated oligosaccharides with terminal sialic acid----Gal----GlcNAc residues similar to glycoproteins secreted by vascular endothelial cells.

Butyrates↗
PubMed1982

Secretory/excretory antigens produced by tetrathyridia of Mesocestoides corti defined by SDS--PAGE and HPLC.

Antigens derived from culture medium in which metacestodes of Mesocestoides corti Hoeppli, 1925, had been maintained were studied by sodium-dodecyl-sulfate--polyacrylamide gel electrophoresis (SDS--PAGE) and high performance liquid chromatography (HPLC). By SDS--PAGE a minimum of 18 Coomassie-staining bands were discerned, of which 4 major bands and 4 major peaks by HPLC of similar molecular weights were observed. The HPLC eluate peaks were analyzed for antigenic activity in vitro by double diffusion in two dimensions, and in vivo in a rabbit. The rabbit had been artificially sensitized with a dialyzable leukocyte extract, showing transfer-factor-like activity, from peritoneal exudate cells removed from mice infected with tetrathyridia. All of the HPLC fractions reacted with rabbit antibody prepared against secretory/excretory antigens, but the sensitized rabbit responded only to two fractions. It is now possible by HPLC to fractionate complex antigens without denaturing them and to elucidate further the role they play during infection.

Animals↗
PubMed1981

Lymphokine-mediated suppression of chondrocyte glycosaminoglycan and protein synthesis.

Spontaneously released and T cell mitogen augmented lymphokine produced by human mononuclear cells has been shown to induce a concentration dependent reversible suppression of chondrocyte glycosaminoglycan and protein synthesis without significantly enhancing chondrocyte catabolic activity. The modulatory factor(s) is of T cell origin and is trypsin, pronase, and heat sensitive. Prostaglandin inhibitors failed to influence factor formation or activity. Although eluting from Sephadex G-100 over a wide range, peak activity had an approximate molecular weight of 53,000 and appeared distinct from recognized forms of lymphotoxin.

Amino Acids↗
PubMed1981

Circulating antigens in infections of mice by tetrathyridia of Mesocestoides corti Hoeppli, 1925.

Two circulating antigens were detected in the serum of ICR/Timco female mice infected intraperitonealy with tetrathyridia of the cestode Mesocestoides corti Hoeppli, 1925. One circulating antigen appeared by day 2 postinfection (p.i.) and remained in all mice until at least 90 days p.i. A second antigen appeared in the serum on day 14 p.i. and disappeared from all mice by day 28 p.i. Infected mouse serum also contained antibodies against one secretory/excretory antigen and two antigens in crude homogenate, as judged by double diffusion in two dimensions (Ouchterlony). Immune deposits were observed in the kidney tissue of Rockland mice by transmission electron microscopy, and their identity as products of tetrathyridia was confirmed by immunofluorescence. Further studies showed that the main antibody subclass associated with the mesangial immune deposits was 7S gamma l, and that other subclasses of IgG and IgM were not involved. Antigen was found in the proximal renal tubules of infected mice, as demonstrated by fluorescein-labeled IgG fraction of rabbit antitetrathyridia secretory/excretory antigen antisera. The presence of tetrathyridia antigen in the urine of infected mice was confirmed using the Ouchterlony technique.

Animals↗
PubMed1977

Phytomitogen-induced, lymphokine-mediated cartilage proteoglycan degradation.

The significance of T-cell activation in the immunopathogenesis of articular disease has been studied in an in vitro model to assess the capacity of phytomitogen-induced lymphokines to degrade cartilage matrix proteoglycans. Supernatants derived from T-cell activation of normal human peripheral blood lymphocytes were shown to contain a monocyte-dependent, serum-inhibitable, dialyzable factor or factors capable of inducing significant proteoglycan degradation, as assessed by release of macroprecipitable 35S-labeled proteoglycan from heterologous cartilage substrates.

Animals↗
PubMed1976

Polydispersity of human articular cartilage proteoglycan antigens.

Studies were undertaken to define more fully the antigenic properties of human articular cartilage proteoglycans, in anticipation of its potential contribution to alterations arising in diseased states and following cartilage transplantation. Proteoglycans, extracted from normal, adult articular cartilage by dissociative measures, were subjected to purification by cesium density gradient ultracentrifugation, under conditions facilitating both molecular aggregation and dissociation. A polydisperse population of reactive determinants was observed in immunodiffusion and hemagglutination inhibition systems, employing proteoglycan specific antisera on gradient fractions. Highly aggregated proteoglycan species appeared to contain potentially masked antigenic determinants, which were revealed after guanidine dissociation but not hyaluronidase digestion. Polyacrilamide disc gel electrophoresis in sodium dodecyl sulfate, in conjunction with disc elution experiments, confirmed proteoglycan antigenic polydispersity.

Adult↗
PubMed1973

Immunopathologic studies in relapsing polychondritis.

Serial studies have been performed on three patients with relapsing polychondritis in an attempt to define a potential immunopathologic role for degradation constituents of cartilage in the causation and/or perpetuation of the inflammation observed. Crude proteoglycan preparations derived by disruptive and differential centrifugation techniques from human costal cartilage, intact chondrocytes grown as monolayers, their homogenates and products of synthesis provided antigenic material for investigation. Circulating antibody to such antigens could not be detected by immunodiffusion, hemagglutination, immunofluorescence or complement mediated chondrocyte cytotoxicity as assessed by (51)Cr release. Similarly, radiolabeled incorporation studies attempting to detect de novo synthesis of such antibody by circulating peripheral blood lymphocytes as assessed by radioimmunodiffusion, immune absorption to neuraminidase treated and untreated chondrocytes and immune coprecipitation were negative. Delayed hypersensitivity to cartilage constituents was studied by peripheral lymphocyte transformation employing [(3)H]thymidine incorporation and the release of macrophage aggregation factor. Positive results were obtained which correlated with periods of overt disease activity. Similar results were observed in patients with classical rheumatoid arthritis manifesting destructive articular changes. This study suggests that cartilage antigenic components may facilitate perpetuation of cartilage inflammation by cellular immune mechanisms.

Adult↗
PubMedDate not supplied

Idiopathic chondrolysis--an immunopathologic study.

Investigations were performed to determine the potential of an immunologically-mediated basis underlying development of severe bilateral knee chondrolysis arising over a 2-yr period in a 29-yr-old man. Humoral and cell-mediated immune responses to autologous and homologous articular cartilage proteoglycan and collagen rich fractions were identified in sequential studies. Employing gradient derived peripheral blood mononuclear cells there was demonstration of spontaneous, T cell mitogen augmented and autologous cartilage antigen-induced release of factors capable of degrading articular cartilage proteoglycans and inhibiting chondrocyte glycosaminoglycan synthesis. Evidence has thus been provided incriminating immunologic events, likely functioning in a perpetuant manner, in the pathogenesis of this chondrolytic process.

Adult↗