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Biomedical subjects

G Camejo

Publications and source records attributed to G Camejo.

At least 91 records · Page 5Linked to original sources
PubMed1976

The affinity of low density lipoproteins for an arterial macromolecular complex. A study in ischemic heart disease and controls.

Levels of serum cholesterol, triglycerides, lipoprotein pattern and the insolubilization of serum low density lipoproteins (LDL, betalipoprotein) by a factor present in arterial intima--media extracts was investigated in 55 patients with acute coronary heart disease and 50 healthy controls. In blood samples obtained 24 h after the episode, the serum betalipoproteins from male normotensive patients showed a high tendency to precipitate when incubated with the intima-media extracts, nearly twice the value measured in the control group. This affinity returned almost to control level after 21 days in the hospital. Hypertensive patients showed a serum cholesterol higher than the controls but almost no difference in LDL-arterial factor interaction. The composition of isolated LDL was studied in 7 patients and 8 controls and it was found that the total cholesterol/protein plus phospholipid ratio has a positive exponential correlation with the lipoprotein-arterial factor affinity. The results of LDL analyses suggest that a change in their composition, frequent in normotensive patients, can lead to an increased affinity of this lipoprotein for arterial intimamedia components. It is proposed that this process could be an additional risk factor contributing to the deposition of LDL in the arterial wall.

Adult↗
PubMed1973

Natural abundance carbon-13 nuclear magnetic resonance spectra of human serum lipoproteins.

Human serum lipoproteins have been studied by Fourier transform nuclear magnetic resonance of carbon-13 in natural abundance. Spectra of highdensity, low-density, and very-low-density lipoproteins were recorded and partly assigned. The prominent features of these spectra reflect the qualitative and quantitative composition of the lipid moiety of these complexes. The results suggest that carbon-13 nuclear magnetic resonance will be a useful technique for studies of the structural and dynamic parameters of lipoproteins.

Carbon Isotopes↗
PubMed1973

Early changes in plasma lipoprotein structure and biosynthesis in cholesterol-fed rabbits.

Plasma lipoproteins of d < 1.063 g/ml from rabbits fed a diet containing 1% cholesterol for 4 days showed changes in concentration and rates of flotation as determined by analytical ultracentrifugation. A marked increase in cholesteryl ester content of lipoprotein with d < 1.019 g/ml was the most prominent change in rabbits fed the diet for 21 days. Gel electrophoresis and immunochemical procedures demonstrated that in control and hypercholesterolemic rabbits there were some common apolipoproteins found in all lipoproteins with density < 1.063 g/ml. In control rabbits, there were also apolipoproteins specific to the lipoprotein fraction with d < 1.019 and to the fraction with d 1.019-1.063 g/ml. However, in rabbits fed the hypercholesterolemic diet for 21 days, the apolipoproteins characteristic of fraction 1.019-1.063 were the most abundant in the fraction with d < 1.019 g/ml. Liver slices from rabbits fed the high cholesterol diet for 7 and 21 days incorporated more l-[(14)C]leucine into very low density and low density lipoproteins than controls. The results suggest that cholesterol feeding leads to an increase in biosynthesis of lipoproteins with d < 1.063 g/ml. The newly synthesized lipoprotein contains apolipoproteins similar to those found in controls but with a higher lipid-to-protein ratio. From the apoprotein composition, it is concluded that the very low density fraction present in cholesterol-fed animals is more structurally related to low density lipoproteins than to the very low density lipoproteins isolated from control animals.

Animals↗
PubMed1970

Ionic channels and nerve membrane lipids. Cholesterol-tetrodotoxin interaction.

Experiments were carried out to investigate possible interactions of tetrodotoxin (TTX) with lipid molecules isolated from nerve fiber plasma membranes of the squid Dosidicus gigas. TTX has a highly selective ability to block the channel normally used by Na(+) to cross the axolemma during nervous impulse conduction. In order to investigate the interaction each lipid sample was spread on 5 x 10(-7)M TTX and TTX-free 0.15 M NaCl solutions adjusted to pH 7.4 with 7 x 10(-3)M phosphate buffer. The surface pressure-area diagrams of the lipid monolayers revealed that TTX interacts only with cholesterol. The expansion of the cholesterol monolayers at 5 x 10(-7)M TTX was 2 A(2)/molecule at zero pressure for the experiments at 20 degrees C and 2.5 A(2)/molecule for those at 25 degrees C. Similar results were obtained in KCl subphases. The apparent dissociation constant of the cholesterol-TTX complex calculated from dose-response experiments is 2.6 x 10(-7)M. Experiments at pH 10.1 revealed that the zwitter ionic form of TTX is less active. Experiments with cholesterol derivatives (cholesteryl acetate, cholesterol methyl ether, cholestanol, and cholestanyl acetate) indicate that for the interaction with TTX a partial negatively charged group at C-3 and a double bond between C-5 and C-6 on the steroid nucleus are required. Tetrodonic acid, a biologically inactive derivative of TTX, does not interact with cholesterol. The results lead us to propose that cholesterol is part of the Na(+) channel.

Animals↗