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Biomedical subjects

P Travo

Publications and source records attributed to P Travo.

29 records · Page 2Linked to original sources
PubMed1986

Mechanical responses of rat vascular smooth muscle cells to rat interferon.

Mechanical responses elicited by rat interferon (IFN) were investigated in rat vascular smooth muscle cells (RVSMC) in primary culture. IFN induced a dose-dependent reduction in the apparent cell surface area, which was quantitatively comparable to, or even greater than, the response elicited by the alpha-adrenergic agent, phenylephrine. Neither mock-IFN nor rat IFN-neutralized with specific antibodies elicited such a response. The sensitivity of RVSMC to the mechanical effect of IFN was species specific. In addition, the effect of IFN was inhibited by the Ca2+ entry blocker, verapamil.

Animals↗
PubMed1984

Discrimination between human melanoma cell lines by fluorescence anisotropy.

The fluorescence polarization of diphenylhexatriene (DPH) and trimethylammonium diphenylhexatriene (TMA-DPH) was measured when these markers were imbedded in cells of the human melanoma cell lines IGR37, IGR39, IGR3 and IGR4, as well as in cells of the mouse melanoma cell lines B16F1 and B16 F10. These measurements were performed on cell cultures which were grown on quartz plates as well as on cell suspensions. Considerable differences are found between the polarization values of the human cell lines that are related to their different origins. Differences for the plated cells are considerably greater than those for the suspensions. No differences in the polarization values were found for the two mouse melanoma lines. It is concluded that differences in lipid structural order can be found between cell types endowed with different metastasizing capabilities.

Animals↗
PubMed1984

Smooth muscle cell hypertrophy and hyperplasia in the thoracic aorta of spontaneously hypertensive rats.

Changes in the smooth muscle cell compartment (SMCC) of the media layer of the aorta were studied in spontaneously hypertensive (SHR) and in normotensive rats (WKY) of both sexes between 3 to 18 weeks of age. Up to 7 weeks of age, development of the SMCC occurred in males and females of the two strains both through a massive increase in cell number and in cell size. In SHR after 7 weeks of age, the development of the SMCC was due to a marked increase in cell size together with an increase in cell number. In contrast during the same period, the development of the SMCC in WKY was associated almost exclusively with an increase in cell size. It is concluded that the presence of a greater number of larger smooth muscle cells contributes to the hypertrophy of the arterial wall of hypertensive animals.

Aging↗
PubMed1980

Differences in proliferation of primary cultures of vascular smooth muscle cells taken from male and female rats.

Vascular smooth muscle cells from thoracic aortas of 10-week-old rats were cultured on different substrates. Cells taken from male animals proliferated more quickly than those taken from females; this was true for all substrates, but the difference was accentuated by growth on collagen membranes. The relationship between these results and the sex-linked incidence of hypertension and atherosclerosis is discussed and a model for future studies proposed.

Animals↗
PubMed1980

[Expression of results in studies of vascular biochemical components during the development of the SHR rat].

Hypertrophy and hyperplasia induced by age and hypertension as well as tissue heterogeneity makes it difficult to analyse biochemical datas obtained with rats thoracic aortas from rats of various age and blood pressure. In SHR, the thoracic aorta weight increases parallely to the body weight from the first week after birth onwards. Meanwhile the protein content of the organ increases parallely to the organ weight. However, though the DNA content increases markedly up to 7 weeks of age, one observes a much lower increase with age afterwards. It seemed to us that the aorta DNA content was more representative of the organ cell number. This led us to use express our biochemical data per mg of the organ DNA content. Moreover, it seems necessary to take in account the cell volume which increases as well with age and hypertension on the one hand, and to be able to distinguish the cellular content of the myocytes from the one of other cells types contained in the adventitia and the intima, on the other hand. For these purposes pure media layers are prepared by completely removing the adventitia and intima and single cell suspensions are obtained after total enzyme digestion of the medias.

Age Factors↗
PubMed1979

Calf spleen NAD glycohydrolase. Comparison of the catalytic properties of the membrane-bound and the hydrosoluble forms of the enzyme.

The catalytic properties of membrane-bound calf spleen NAD glycohydrolase were studied in comparison with previous data obtained with a solubilized hydrosoluble form of the enzyme. When the hydrolysis of NAD catalyzed by membrane-bound NAD glycohydrolase was studied at pH values below 7.5, only insignificant interference by other NAD-hydrolyzing enzymes was detected, and no proton-diffusional inhibition was observed. The kinetics could, therefore, be followed using a titrimetric assay for NAD glycohydrolase activity. The effect of pH, ionic strength on the kinetic parameters, and shifts in binding constants for several ligands of the membrane-bound enzyme indicate that the NAD glycohydrolase activity is influenced by an electrostatic potential due to negative charges (polyelectrolyte effect). No significant changes in kinetic mechanism could be found between both NAD glycohydrolase forms. The association of the enzyme with the membrane results in a remarkably increased thermal stability, in changes in binding properties of the active site and in the emergence of new inhibitor binding sites; e.g. adenosine 3':5'-monophosphate (cyclic AMP) and adenosine, which do not inhibit the hydrosoluble form of NAD glycohydrolase, are good inhibitors (respectively competitive and mixed) of the membrane-bound enzyme. These data (i.e. allotopic changes) probably can be ascribed to enzyme conformational changes induced and stabilized by interaction with membrane constituents.

Animals↗
PubMed1978

Calf-spleen nicotinamide-adenine dinucleotide glycohydrolase. Properties of the active site.

The interaction between the nicotinamide adenine dinucleotide binding domain of calf spleen NAD glycohydrolase and its ligands has been studied. The use of competitive inhibitors, structurally related to different portions of the NAD molecule (i.e. adenosine and nicotinamide moieties), revealed the considerable importance of the binding between the pyrophosphate linkage and probably an arginyl residue of the active site. This interaction allows the positioning of the substrate in a conformation which permits catalysis to occur. The binding between the 2'-hydroxyl of the adenosine moiety and a residue of the active site, which exists in NAD-linked dehydrogenases, is probably missing in the calf spleen NAD glycohydrolase, based on the inhibition by salicylates, 2'-deoxyadenosine 5'-monophosphate and the hydrolysis of the 2'-deoxyadenosine analogue of NAD. The NAD glycohydrolase could be completely inactivated by 2,3-butanedione, an arginyl-modifying reagent. The reaction followed pseudo-first-order kinetics and the modification was found to be reversible. Woodward's reagent K, a reagent for carboxyl residues, partially inactivated the enzyme, which resulted in a change of the NAD glycohydrolase kinetic parameters Km and V. The inactivation rate was complicated by a parallel decomposition of the reagent.

Adenine Nucleotides↗
PubMed1976

Calf-spleen nicotinamide--adenine dinucleotide glycohydrolase. Solubilization purification and properties of the enzyme.

NAD glycohydrolase of calf spleen was solubilized with pancreatic lipase and purified approximatively 800-fold to a specific activity of 7 units/mg of protein by successive DEAE-cellulose and carboxymethyl-cellulose chromatography. The purified enzyme has a molecular weight of 24,000 and is characterized by a double band on disc gel electrophoresis. Some kinetic properties of the NAD-glycohydrolase-catalyzed hydrolsis of NAD have been examined using a titrimetric assay for enzyme activity. The reaction is subject to inhibition be excess of substrate, which disappears at high ionic strength and low pH. At a pH below 5 the kinetic displays an apparent activation by substrate. The effects of pH (4.5-9.0) on the kinetic parameters do not reveal an essential ionizable group in the catalytic process.

Animals↗