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Biomedical subjects

H B Bosmann

Publications and source records attributed to H B Bosmann.

At least 37 records · Page 2Linked to original sources
PubMed1982

Platelet aggregation: inhibition of secondary aggregation by phenol.

Abnormal platelet function in patients with chronic renal failure has been associated with elevated levels of phenol and phenolic acids in serum. In vitro studies show inhibition of secondary aggregation by phenol, suggesting that phenol acts at the platelet release reaction. When platelet rich plasma was incubated with phenol, inhibition was found to decrease with increasing preincubation time at 37 degrees C, but not at 0 degree C. Also, the inhibitory effect of phenol in vitro was overcome by the addition of arachidonic acid. These findings demonstrate inhibition of secondary aggregation by phenol. Thus the site of the inhibitory action of phenol was at the initiation of the secondary wave of platelet aggregation.

Adenosine Diphosphate↗
PubMed1982

Resting state depth and saturation density as modulated by tumor promoters and culture conditions: relationship to chemical transformation in C3H/10T1/2 cells.

With the use of cultures of C3H/10T1/2 fibroblasts, the relationships of saturation density and cell resting state (Go) depth to oncogenic transformation by 3-methylcholanthrene (MCA) were investigated. The tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA), caused a small increase in the saturation density, but saccharin (SAC), a suspected promoter, did not, Correspondingly, TPA tested positively as a promoter of transformation in a typical two-stage transformation assay with these cells while SAC did not. By altering the confluent-phase serum concentration and/or the medium renewal frequency of MCA-treated cultures, it was found that the magnitude of transformation for a given concentration of MCA was independent of the saturation density. Oscillations in this density were observed even when the medium was renewed as frequently as every 3 days, indicating that cell death and replacement occur during what is generally regarded to be a period of cellular stability. Neither TPA nor SAC blocked the cells from progressing into deeper resting states over time, as indicated by the prereplicative lag time after a medium change at 42 days. However, the serum concentration and medium renewal frequency did affect the resting state depth. Daily renewals with medium containing 10% serum blocked the resting state from deepening and kept the cells from achieving a saturation density. Under these circumstances, transformation was completely inhibited in MCA-treated cultures.

Animals↗
PubMed1982

Demonstration of direct toxicity of phenol on kidney.

The effect of phenol on the rat kidney was investigated by means of an arterial infusion designed to deliver isotonic phenol solutions directly to the renal circulation. Cortical lesions, consisting primarily of vacuolization and dilation of proximal tubules and sloughing of the apical cytoplasm, increased in severity with increasing phenol dose. Specific staining techniques allowed the detection of effects on the brush borders and basement membranes of tubules. Evidence was also offered for hemolysis products not reaching the proximal tubules. These findings are consistent with a direct effect of phenol on the kidney.

Animals↗
PubMed1981

Measurement of the electrokinetic properties of vaccinia and reovirus by laser-illuminated whole-particle microelectrophoresis.

The electrokinetics of vaccinia virus and reovirus type 3 were studied in dilute electrolyte solutions by whole-particle microelectrophoresis with dark-field laser illumination. The electrophoretic mobilities were dependent upon pH and electrolyte composition. The isoelectric point of vaccinia virus in dilute NaCl was 4.8 +/- 0.1; that of reovirus was 3.8 +/- 0.1. The mobility of reovirus was -2.65 +/- 0.30 micrometer . S-1 . V-1 . cm-1. Treatments known to cause irreversible changes in the structure of vaccinia, such as heating to 90 degrees C or exposure to pH 10, altered the virus's mobility under the reference conditions. The practical range of whole-particle microelectrophoresis thus extends to microorganisms as small as reovirus, allowing their electrokinetic and related surface properties to be studied.

Bicarbonates↗
PubMed1981

Neuraminidase activity and cell surface sialic acid turnover in Rous sarcoma virus transformed chick embryo fibroblasts.

Neuraminidase activity of Rous sarcoma virus transformed chick embryo fibroblasts (RSV-CEF) was assayed using an exogenous substrate, neuraminlactitol-[3H], and endogenous, cell surface [14C]-N]-acetyl-neuraminic acid. RSV-CEF had higher neuraminidase activity toward both substrates than did chick embryo fibroblasts (CEF) or nontransformed, Rous associated virus infected CEF (RAV-CEF). The total sialic acid content of RSV-CEF was lower than CEF or RAV-CEF, and more of the total sialic acid was accessible to extracellular Clostridium perfringens neuraminidase. Activity of the enzymes synthesizing and degrading the substrate for sialyltransferase, cytidine-5'-monophosphate-N-acetyl-neuraminic acid (CMP-AcNeu) was measured in order to determine whether control of substrate levels for sialyltransferase might contribute to the decreased levels of glycoprotein bound sialic acid. No change in activity of these enzymes was found in RSV-CEF as compared to CEF or RAV-CEF.

Animals↗
PubMed1980

Chemical carcinogen in vitro testing: a method for sizing cell nuclei in the nuclear enlargement assay.

The observation that cells often respond to carcinogens by nuclear enlargement has suggested that this property might be useful to develop a short-term screening test for such compounds. Previous methods for detecting nuclear size increases have used an image analyzer system to detect nuclear changes in individual cells. This paper details a more rapid method for obtaining nuclei by use of a stromalyzing procedure following by analysis of nuclear volumes, using a Coulter Counter Channelyzer. This new and simplified nuclear sizing method should facilitate the use of the assay as a possible carcinogenesis screen by permitting rapid and efficient testing of large numbers of compounds.

Carcinogens↗
PubMed1980

Diazepam receptor: specific nuclear binding of [3H]flunitrazepam.

Autoradiographic localization of [3H]flunitrazepam in nuclei of the rat cerebral cortex was further confirmed by biochemical analysis of specific nuclear binding. Highly purified rat cerebral cortex nuclei were shown to bind [3H]flunitrazepam specifically. The Kd(app) for nuclear binding was 28 nM for the nuclei compared with a Kd(app) of 1.1 nM for binding of [3H] flunitrazepam to synaptosomal membrane fractions of the same tissue. Inhibition of the nuclear binding with inosine and hypoxanthine was greater than inhibition of the synaptic membrane fractions. These results lead to to conclude that specific binding may occur at both the synaptic membrane and the nuclear levels and that different endogenous ligands may compete at each site for binding. Furthermore, the possibility exists for translocation and alteration of the bound ligand complex from membrane site to nuclear site.

Animals↗
PubMed1980

Correlation of serum, tumor, and liver serum glycoprotein: N-acetylneuraminic acid transferase activity with growth of the R3230AC mammary tumor in rats and relationship of the serum activity to tumor burden.

The observation that the activity of sialyltransferase (EC 2.4.99.1; serum glycoprotein:N-acetylneuraminic acid transferase) is often elevated in the serum of cancer patients necessitates an elucidation of the interrelationships of this serum enzyme with host tissues. Accordingly, the activity of this enzyme in serum, tumor, and liver was determined at various times after implantation of the R3230AC mammary carcinoma into Fischer rats. Results from samples obtained at numerous, sequential time points demonstrated that significant elevations in serum sialyltransferase enzyme activity occurred only in animals bearing large tumor burdens, i.e., greater than 20 g, or in animals with tumors present for longer than 21 days. In these tumor-bearing rats, the activity of sialyltransferase increased in liver tissue at 21 to 25 days concurrently with the increase in serum enzyme activity, suggesting that the liver may be a potential source of the serum enzyme. Sialyltransferase activity in tumor tissue was quite variable; the activity increased one week after tumor implantation and remained at the same level thereafter. When tumors were excised, the activity of the serum enzyme returned to control values within four days after surgery, suggesting that the half-life of serum sialyltransferase was two days. Serum enzyme levels were again elevated upon regrowth of the tumor. These results show that the serum sialyltransferase alters its activity in conjunction with changes in tumor burden.

Adenocarcinoma↗
PubMed1979

Sialyltransferase activities of aging diploid fibroblasts.

Sialyltransferase activity and cell-cell adhesion rates of aging WI-38 cells were studied to determine the possible basis for a previously described decrease in membrane bound sialic acid and loss of proliferation of senescent cells. Ectosialyltransferase was demonstrated on the surface of both young and old WI-38 cells. The sialyltransferase assays consist of an enzyme source which is either the surface of intact cells (ectoenzyme) or a Triton X-100 cell homogenate, the nucleotide sialic acid donor (cytidine monophosphate-N-acetylneuraminic acid), and an asialo-acceptor which may be endogenous to the enzyme preparation or may be added exogenously. When sialyltransferase activity is measured in the absence of exogenous acceptors, there is a greater amount of sialic acid transferred by odl cells. However, when exogenous acceptors are provided, the amount of transfer is stimulated to a greater extent in young cells equalizing the amount of sialic acid incorporated into young and old cells. This suggests that there are fewer asialoglycoproteins and that acceptor concentration is a limiting factor in assays of young cell sialyltransferase. The end result of this may be the previously described decreased amount of membrane-bound sialic acid of old cells. A change in the adhesiveness of old cells is described which may be related to the altered cell surface.

Cell Adhesion↗
PubMed1979

Glycoprotein galactosyltransferase activity in synaptic junctional complexes isolated from rat forebrain.

A synaptosomal plasma membrane fraction and its junctional and nonjunctional subfractions were isolated and analyzed for glycoprotein galactosyltransferase activity. The nonjunctional components fraction had the highest specific activity in the presence of exogenous acceptor, suggesting an enrichment of enzyme in this fraction. The synaptic junctional complex fraction had the highest specific activity in the absence of added acceptor, suggesting that there is a relative enrichment of endogenous acceptors for this galactosyltransferase within the synaptic junctional complex.

Animals↗