Archivos de biologia y medicina experimentales最新文献

This paper describes the isolation, purification and full characterization of the protamine from Sardinops sagax. The protein was purified by both gel filtration and ion exchange chromatography and its amino acid composition, electrophoretic behaviour and sequence were determined. We postulate that the protamine exhibits microheterogeneity with a major and a minor component. The molecular weight for the major component is 4377, as calculated from the sequence. The N-terminal amino acid is proline and the C-terminal is arginine. The amino acid composition is: Thr-Ser-Glx-(Pro)2-Gly-(Ala)3-(Val)2-(Lys)2-(Arg)20 The secondary structure for the protamines was also predicted and a revision of our previously published results in this area is discussed. We have called this protamine Sagaxine and an overall comparison with the hitherto described fish protamines is also made.

The level of blood lipids in children with Down's syndrome was determined with the purpose of establishing possible differences in total cholesterol, triglyceride and HDL-cholesterol levels with those of healthy children. LDL-cholesterol fraction was calculated. Blood samples were obtained from 66 healthy children (controls) and 72 patients who suffered from clinically diagnosed Down's syndrome. All the children were grouped according to age. The variables of body weight, height, and blood lipids gave a distribution of values that allows one to distinguish the group of children with Down's syndrome from the normal group. The values obtained for triglycerides, total cholesterol, and LDL-cholesterol ranged higher, with a constant deficit of HDL-cholesterol in all age groups. The lipid pattern encountered in the Down's syndrome patient suggests the existence of unknown, possibly genetically determined mechanisms, that provoke a disorder in lipid metabolism.

Parotid gland saliva was collected from three groups of Chilean human subjects: Down syndrome, non-Down mentally retarded, and normal individuals. Their salivary flows, pH and electrolyte concentrations were determined. Variables were subjected to ANOVA statistical tests that showed no differences between Down and control groups in salivary flow, pH, chloride, sodium and bicarbonate concentrations. The potassium concentration in the saliva from Down syndrome patients was significantly lower than that of control individuals. Student's t-tests showed significant differences between Down syndrome individuals and controls for potassium and sodium. These last differences may be indicative of a characteristic trait of the trisomic state or of the syndrome itself.

We use analysis of co-citation and relative citation rates to assess the scientific strength of Chile as compared with other developing countries and to evaluate the potential for increased international collaboration between Chile and the United States in science and engineering. Co-citation is the citation of two scientific papers by a third paper. By examining frequency and patterns of co-citation, the intellectual structure and evolution of scientific disciplines and research specialties can be traced. Chile is especially "strong", as defined by the co-citation model we employ, in biomedicine and clinical medicine, and in astronomy. A relative citation rate is the ratio of the number of citations a paper receives to the average number of citations for all papers published in the same journal over time. Analysis of relative citation rates of papers published by authors with Chilean addresses show that Chilean physics, including earth and space sciences, is of unusually high quality, considerably higher than any other developing country and comparable to several industrialized countries. We conclude that Chile's scientific capacity is advanced enough to absorb and benefit significantly from strategic additions to the country's resources and capabilities for research. These would include increases in: exchanges of researchers in specific fields with U.S. and other Latin American academic, industrial, and government scientists and engineers; training at outstanding U.S. and Latin American institutions; laboratory equipment, computer time, communications links, and library materials; and funding from U.S. and international organizations. It is also apparent that Chile is strong enough in certain fields to cooperate with the U.S. in mutually beneficial international efforts.