PubMed Health⌕ Search

Biomedical subjects

T S Tralka

Publications and source records attributed to T S Tralka.

At least 19 recordsLinked to original sources
PubMed2000

Seroprevalence and ethnic differences in Helicobacter pylori infection among adults in the United States.

The seroprevalence of Helicobacter pylori infection was examined in the adult US population and among different ethnic groups. Stored sera from 7465 adult participants in the first phase of the third National Health and Nutritional Examination Survey (1988-1991) were tested with a sensitive and specific IgG ELISA, to diagnose infection. Seroprevalence of H. pylori among all participants was 32. 5%. This increased with age, from 16.7% for persons 20-29 years old to 56.9% for those > or =70 years old. Age-adjusted prevalence was substantially higher among non-Hispanic blacks (52.7%) and Mexican Americans (61.6%) than among non-Hispanic whites (26.2%). After controlling for age and other associated factors, the odds ratios relative to non-Hispanic whites decreased for non-Hispanic blacks, from 3.9 (95% confidence interval [CI], 3.1-4.9) to 3.3 (95% CI, 2. 6-4.2), and for Mexican Americans, from 6.3 (95% CI, 4.8-8.3) to 2.3 (95% CI, 1.6-3.5). The high prevalence of H. pylori infection among non-Hispanic blacks and Mexican Americans is partially explained by other factors associated with infection.

Adult↗
PubMed1995

The role of transjugular intrahepatic portosystemic shunt for treatment of portal hypertension and its complications: a conference sponsored by the National Digestive Diseases Advisory Board.

TIPS is a new and exciting modality for treatment of portal hypertension and its complications. Indications for TIPS remain to be better defined in terms of efficacy and cost-benefit in relationship to other established modes of therapy of portal hypertension. Prospective, randomized controlled trials are needed for these comparisons. Until the role of TIPS in the routine management of the complications of portal hypertension is better defined, TIPS should be used only in situations in which conventional medical and endoscopic therapies have failed.

Humans↗
PubMed1986

Synergistic effects of butyrate on platelet responses to arachidonate, A23187, PGE1, and forskolin.

With eukaryotic cells, butyrate is known to induce a series of morphological and biochemical changes that mimic cellular differentiation. With platelets, we have found that butyrate (10 mmol/L) caused an approximately threefold increase in sensitivity to calcium ionophore A23187 and arachidonate. Maximum aggregation was observed at agonist concentrations of 3 mumol/L and 170 mumol/L, respectively, as compared with required concentrations of 10 mumol/L and 400 mumol/L in the absence of butyrate. Similar effects were seen with isobutyric acid, and about one-half the effect was shown with valerate and caproate, but lower homologues showed no synergistic effect. No ultrastructural changes were observed in platelets incubated with butyrate, and the aggregation effects were reversible and returned to normal on removal of butyrate. Membrane fluidity was unchanged by butyrate as measured by changes in the fluorescence depolarization of diphenylhexatriene. Butyrate caused a 60% to 70% increase in the uptake of 3H-arachidonate. Butyrate also potentiated the inhibition of platelet function by prostaglandin E1 and forskolin and uptake of 3H-forskolin was increased approximately 20%. In contrast, platelet response to other agonists (ADP, epinephrine, collagen, thrombin, and platelet-activating factor) was essentially unaffected by butyrate. These results suggest that butyrate may increase the uptake of certain hydophobic agonists and antagonists by platelets. Similar mechanisms for uptake of endogenous effectors may explain the response of eukaryotic cells to butyrate in culture.

Alprostadil↗
PubMed1984

pH-dependent fusion induced by vesicular stomatitis virus glycoprotein reconstituted into phospholipid vesicles.

Purified G-protein from vesicular stomatitis virus was reconstituted into egg phosphatidylcholine vesicles by detergent dialysis of octyl glucoside. A homogeneous population of reconstituted vesicles could be obtained, provided the protein to lipid ratio was high (about 0.3 mol % protein) and the detergent removal was slow. The reconstituted vesicles were assayed for fusion activity using electron microscopy and fluorescence energy transfer. The fusion activity mediated by the viral envelope protein was dependent upon pH, temperature, and target membrane lipid composition. Incubation of reconstituted vesicles at low pH with small unilamellar vesicles containing negatively charged lipids resulted in the appearance of large cochleate structures, as shown by electron microscopy using negative stain. This process did not cause leakage of a vesicle-encapsulated aqueous marker. The rate of fusion was pH-dependent with a pK of about 4 and the apparent energy of activation for the fusion was 16 +/- 1 kcal/mol. G-protein-mediated fusion showed a large preference for target membranes which contain phosphatidylserine or phosphatidic acid. Inclusion of 36% cholesterol in any of the lipid compositions had no effect on the rate of fusion. These reconstituted vesicles provide a system to study the mechanism of pH-dependent fusion induced by a viral spike protein.

Animals↗
PubMed1984

Mixed infection with human cytomegalovirus and human polyomavirus (BKV).

Mixed infection, the infection of a single cell by two distinguishable viruses, has been demonstrated electron microscopically in human embryo lung (HEL) and human embryo kidney (HEK) cells infected with human cytomegalovirus (HCMV) and human polyomavirus (BKV). There was no evidence of enhancement of HCMV by BKV in either cell system; however, in HEL cells under certain conditions, HCMV enhanced the growth rate of BKV. Since both BKV and HCMV are often found in the urine of immunosuppressed patients, the enhancement of BKV by HCMV may be of clinical significance.

Cells, Cultured↗
PubMed1983

Inhibition of VSV binding and infectivity by phosphatidylserine: is phosphatidylserine a VSV-binding site?

Recently we described a saturable, high-affinity binding site for vesicular stomatitis virus (VSV) on the surface of Vero cells that appears to mediate viral infectivity. To isolate this binding site, we have extracted Vero cells with the detergent, octyl-beta-D-glucopyranoside. The dialyzed detergent extract specifically inhibits the saturable, high-affinity binding of 35S-methionine-labeled VSV to Vero cells. The inhibitory activity is resistant to protease, neuraminidase and heating to 100 degrees C. It is soluble in chloroform-methanol and inactivated by phospholipase C, suggesting that it is a phospholipid. Of various purified lipids tested, only phosphatidylserine was capable of totally inhibiting the high-affinity binding of VSV. The half-maximal inhibitory concentration for phosphatidylserine was 1 microM. Phosphatidylserine also inhibited VSV plaque formation by 80%-90%; Herpes simplex virus plaque formation was unaffected. Centrifugation and electron microscopy studies have shown that phosphatidylserine-containing liposomes bind to VSV. The finding that phosphatidylserine directly binds to VSV and inhibits VSV attachment and infectivity suggests that plasma membrane phosphatidylserine could function as a binding site or portion of a binding site for VSV.

Animals↗
PubMed1983

Demonstration of type-R and type-C virus particles in hamster pancreatic adenocarcinomas.

Two transplantable solid tumors (CBP and PDP) and two continuous cultured cell lines (CBP-TC and PDP-TC) were established from nitrosamine-induced pancreatic ductal adenocarcinomas in inbred Syrian hamsters. Electron microscopic examination of both CBP and PDP solid tumors as well as CBP-TC cultured cells revealed the presence of type-R virus particles, which consisted of a 100 nm envelope containing a central 50 nm nucleoid with characteristic radiating 'spokes'. Type-R particles were abundant in cultured CBP-TC cells, moderately frequent in CBP solid tumors, and rare in PDP solid tumors; they were not present in PDP-TC cultured cells. The CBP and PDP solid tumors and cultured PDP-TC cells exhibited type-C viral particles, having a 150 nm envelope containing a 75 nm nucleoid. Mature, immature and budding forms of Type-C viruses were present and quite prominent in PDP tumors. Type-C particles were present but rare in CBP solid tumors and in PDP-TC cells. C-particles were not observed in cultured CBP-TC cells. Examination of normal hamster pancreas, liver, duodenum, muscle and connective tissue failed to reveal evidence of type-R or type-C virus particles. It is important to recognize the presence of virus particles in hamster pancreatic carcinoma lines, since viruses could potentially affect biochemical or immunological studies on the carcinomas through the production of viral proteins that could be mistaken for tumor-associated antigens.

Adenocarcinoma↗
PubMed1983

Butyrate increases type-A and type-R virus-like particles in BKV-transformed hamster spleen cells.

A cell line derived from hamster spleen transformed by human papovavirus BK was adapted to grow in 5 mM butyrate. Ultrastructurally, the butyrate-adapted cells were found to contain large numbers of type-R and intracytoplasmic type-A virus-like particles (VLP). In contrast, the unadapted cells contained only rare VLP. Treatment of the unadapted cells with nontoxic and toxic concentrations of butyrate for 24 and 48 hr failed to induce VLP, indicating the importance of butyrate adaptation in the induction of VLP. The increase in type-R VLP was stable after removal of the adapted cells from butyrate; however, the increase in type-A VLP was not.

Animals↗
PubMed1983

Murine type C retroviruses and intracisternal A-particles in human tumors serially passaged in nude mice.

An ultrastructural survey of 11 human tumors passaged in N:NIH(S) (nu/nu) mice showed two instances of type C virus production. In one instance type C virus particles were observed in the endothelial murine stromal cell component of an embryonal carcinoma but not in the human tumor cells. In another instance type C virus particles were seen replicating in the chondroblastic human cells of a xenografted osteosarcoma. The type C virus produced in the human cells failed to transform NIH/3T3 cells, the C-127 rat cell line, or mink cells. Nucleic acid hybridization studies in which a human endogenous retroviral probe and a xenotropic murine leukemia virus envelope probe were used suggested that the retrovirus present in the human osteosarcoma cells is related to murine leukemia viruses. Intracisternal A-particles (IAP) were also detected in the human osteosarcoma cells. Their presence in the human cells was demonstrated by simultaneous visualization of IAP and human HLA determinants at the cell surface. The literature on type C virus infection of human cells and tumors grafted in nude mice is reviewed.

Animals↗
PubMed1983

Fibronectin-mediated attachment of hematopoietic cells to stromal elements in continuous bone marrow culture.

Hematopoiesis in continuous bone marrow culture is dependent upon close-range interaction between hematopoietic cells and marrow-derived adherent cells. The latter have been shown to include a significant proportion of fibroblastic elements, synthesizing the attachment protein fibronectin. The role of fibronectin in continuous bone marrow culture was therefore investigated. Continuous marrow cultures were stained by the peroxidase-anti-peroxidase technique, using an affinity-purified anti-fibronectin antibody. The stained cultures were then examined by transmission electron microscopy for the presence of fibronectin at sites of cellular attachment. Fibronectin was detected on the substratum attachment surfaces of marrow-derived adherent cells and at sites of interaction between stromal elements in the adherent layer. Fibronectin was also detected at many attachment sites between marrow-derived adherent cells and developing granulocytes and monocytes. The possible significance of these observations is discussed in relation to the hematopoietic microenvironment.

Animals↗
PubMed1982

Isolation of a subunit of laminin and its role in molecular structure and tumor cell attachment.

Laminin, the glycoprotein of basement membranes, migrates as two components of 200 kilodaltons (kDa) (alpha subunit) and 400 kDa (beta subunit) after reduction on polyacrylamide gel electrophoresis. We have isolated the alpha subunit and studied its structure by electron microscopy and its function as an attachment factor for tumor cells. Using selective proteolysis of laminin by alpha-thrombin, the beta subunit was removed without any change in the quantity or size of the alpha subunit. Removal of the beta subunit caused a 35-40% decrease in the total mass of the laminin molecule. The alpha and beta subunits differed by 50-fold in the amount of reducing agent required for complete migration on polyacrylamide gels. By electron microscopy, the whole laminin molecule appeared as a "cross" with three identical short arms (37 nm) and one long arm (75 nm). The alpha subunit examined by electron microscopy was missing the long arm and had no change in the length of the three short arms. This subunit of laminin mediated the attachment of human squamous carcinoma cells to type IV collagen. Such attachment properties were lost after pepsin treatment which is known to remove the globular end regions of the short arms. We conclude that the beta subunit of laminin is embodied in the long arm of the molecule and that the alpha subunit consists of three similar chains of 200 kDa. The globular end regions of the laminin short arms are required for the attachment of tumor cells to type IV collagen.

Animals↗
PubMed1982

Detection by immune electron microscopy of the Snow Mountain agent of acute viral gastroenteritis.

An extensive outbreak of acute gastroenteritis of unknown etiology occurred at Snow Mountain, Colorado, in December 1976. Virus-like particles, 27 nm in diameter, were observed by electron microscopy in two of five stool specimens from individuals in the outbreak. Oral administration of a filtrate from one of the specimens induced disease in nine of 12 normal volunteers. Experimentally induced illness was similar to that observed during the outbreak. Stool specimens examined by immune electron microscopy revealed 27-nm virus-like particles in three of nine ill volunteers at the onset of illness. When the particles were used as a source of antigen, increases in levels of serum antibody were demonstrated in persons with either experimentally induced or naturally occurring illness. Therefore, it is likely that this virus-like particle is the etiologic agent of the Snow Mountain outbreak. The Snow Mountain agent appears to be morphologically similar to, but antigenically distinct from, the Norwalk and Hawaii agents by immune electron microscopy and may represent an additional antigenic type among the agents that resemble the Norwalk particle.

Adolescent↗
PubMed1982

Characterization of marrow-derived adherent cells. Evidence against an endothelial subpopulation.

Cultured, marrow-derived, adherent cells (MDAC) provide a microenvironment which supports the proliferation of haemopoietic stem cells (HSC) for extended periods in vitro. Morphological characterization suggested that MDAC populations consisted of a variety of cell types, including mononuclear phagocytes, fibroblastoid cells, fat cells and vascular endothelial cells. Recently performed functional characterization studies suggest that they consist largely of collagen-producing, fibroblastic cells. MDAC were not, however, examined systematically for endothelial cell characteristics. Unrecharged cultures of MDAC, shown in parallel studies to support in vitro haemopoiesis, were examined for endothelial cell markers. These included the presence of Weibel-Palade bodies and synthesis of factor VII related antigen. They were also examined biochemically for synthesis of basement membrane (type IV) collagen. The results of these investigations were negative in all cultures examined. It is thus concluded that vascular endothelial cells are not present as a significant component of the unrecharged MDAC population and do not, therefore, contribute to the functional haemopoietic microenvironment in vitro or in vitro.

Animals↗
PubMed1982

Evidence for acute cellular changes in human hepatocytes during anesthesia with halogenated agents: an electron microscopic study.

Liver biopsy specimens of 24 patients who had elective laparotomies were studied by electron microscopy for evidence of anesthesia-related toxic changes. All patients were initially anesthetized with nitrous oxide, barbiturate, and narcotic until the laparotomy incision was completed and an initial preanesthesia liver biopsy specimen was taken. Patients were then give, in randomized fashion, maintenance inhalational anesthesia for the duration of the procedure with halothane, fluroxene, or enflurane. Control patients were continued on nitrous oxide, barbiturate, and narcotic. After approximately 60 minutes a second postanesthesia liver biopsy specimen was taken. For each patient, the preanethesia and postanesthesia liver biopsy specimens were compared, in blinded fashion, for evidence of morphologic changes resulting from anesthesia. Ultrastructural changes consistent with hepatic toxicity were present in more than 25% of the cells examined in the postanesthesia specimens in all of the seven patients given halothane, five of the six patients given fluroxene, and one of the five patients given enflurane. None of the six nitrous oxide-barbiturate-narcotic control patients showed toxic changes in postanesthesia specimens. The most prominent toxic change was dilatation of endoplasmic reticulum. Accumulation of intracellular inclusions occurred in some cells, and a small percentage of cells also showed lipid accumulation and mitochondrial swelling. Evidence suggested that exposure to halogenated anesthetics is related to acute toxic subcellular changes in hepatocytes.

Adolescent↗
PubMed1981

Phagocytic properties of bone marrow fibroblasts.

Phagocytic activity has been observed in cultured marrow derived adherent cells (MDAC). Characterization studies indicate that these populations consist largely of collagen-producing fibroblasts, having failed to reveal markers associated with mononuclear phagocytes (MNP). Phagocytic activity by MDAC was therefore investigated. Characterization studies again failed to demonstrate an Fc receptor and confirmed that human MDAC synthesize collagen in vitro. Phagocytic activity against polystyrene microspheres was observed in 40% of MDAC. Control studies using P-8 and WI-38 fibroblasts yielded similar results. MDAC, P-8 and WI-38 fibroblasts were exposed to fluorescent microspheres and subsequently stained by immunofluorescence for type I collagen. Many cells were seen both to contain fluorescent particles and to stain positively for type I collagen. These results indicate that marrow derived fibroblasts, in common with fibroblasts from other sources, have phagocytic capability under appropriate conditions.

Bone Marrow Cells↗
PubMed1980

Search for retrovirus-like particles in human breast cancer cells in culture.

We have recently established four new human breast cancer cell lines that were characterized as being of human mammary origin. We examined these cell lines for particles morphologically resembling retroviruses by electron microscopy, for extracellular and intracellular particles containing high-molecular-weight RNA and RNA-directed DNA polymerase by biochemical assays, and for mouse mammary tumor virus (MMTV)-related sequences in the cell genomes by molecular hybridization. An extensive search for budding particles by thin-section electron microscopy of cells did not provide evidence for retrovirus-like particles. Similarly, 1000- to 2000-fold concentrated samples of medium harvested from 10(8) cells did not contain particles of a density of 1.14 to 1.16 g/ml containing RNA-directed DNA polymerase. Compared with DNA polymerase activity of MMTV, and taking into account the particle weight and protein content of retroviruses, we estimate that, if these cells produce retrovirus-like particles, this production would be less than 1.6 particles/cell every 24 to 72 hr. The hybridization of cell DNA with MMTV complementary DNA also did not show detectable amounts of virus-related sequences in the cell genome. Analysis of the hybridization results suggested that, if the human breast cells contained MMTV-related sequences, they must be present in less than one copy per 100 cells. Thus, we have obtained no convincing evidence for the presence of retrovirus-like particles or subviral components in these cells. It is of course possible that these cells contain virus information but at levels below the sensitivity of our assay procedures.

Breast Neoplasms↗