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Biomedical subjects

M Gonzalez

Publications and source records attributed to M Gonzalez.

11 recordsLinked to original sources
PubMed1979

Sulfatide content and (Na+ + K+)-ATPase activity of skin and gill during larval development of the Chilean frog, Calyptocephalella caudiverbera.

The sulfatide content, phospholipid concentration, and (Na+ + K+)-ATPase activity from skin and gills of different stages of larval development of Calyptocephalella caudiverbera (a Chilean frog) were analyzed. Additionally, the short-circuit current in skin was studied. When skin and gills, depending on the stage of larval development, present (Na+ + K+)-ATPase activity, they have a high ratio of sulfatide to amount of membrane and the phosphatidylserine concentration remains unchanged. Sulfatide content and (Na+ + K+)-ATPase activity in skin are in direct relationship with the level of sodium flux present during development. The specific enzymatic hydrolysis of sulfatide with partially purified arylsulfatase of pig kidney inhibits 100% of the ouabain-sensitive (Na+ + K+)-ATPase. The ouabain-insensitive ATPase remains virtually unchanged with the treatment, even with a high concentration of arylsulfatase or with ouabain present in the medium. These experiments strongly suggest a role of sulfatides in the (Na+ + K+)-ATPase activity and, as a consequence, in sodium ion transport.

Animals↗
PubMed1979

Stereochemistry of holoaspartate transaminase after modification of the active site Lys-258.

Proton incorporation at position C4 of the substrate-coenzyme Schiff base of aspartate transaminase is a stereospecific process. After carbamylation of the active site Lys-258, the stereospecificity of the reaction in 2H2O is retained. By a correlation method, it is shown that addition occurs from the si side of the complex and the pyridoxamine phosphate produced is deuterated at position pro-S of the pyridoxamine methylene group. These results constitute a demonstration for the stereochemstry of a half-transamination process of the phosphorylated coenzyme under single turnover conditions. They also illustrate that free Lys-258 is not required to maintain stereospecificity and cast doubts on the implication of this residue as a participant in C4 proton addition during catalysis by the native form of this mammalian enzyme.

Animals↗
PubMed1979

Acute lymphatic leukemia with mediastinal involvement.

Mediastinal involvement was found in 11 (group A) of 43 patients affected with acute lymphatic leukemia when early thoracic roentgenograms of these patients were reviewed. Several clinicobiological characteristics of these patients were compared with those with a normal mediastinum as shown in their roentgenograms (group B). Statistically significant differences were observed between group A and group B not only as far as age was concerned (13 years group A, 7.4 years group B) but also in the ratio males/females (10:1 group A, 10:20 group B) and with regard to the leukocyte counts (266 x 10(9)/liter group A, 20 x 10(9)/liter group B). In addition, patients from group A showed a greater 'tumoral mass' and a more prominent extrahematological involvement (45% group A, 15% group B). In these cases 'convoluted' cells were frequently discovered and the blastic cells exhibited significantly lower scores of PAS-positivity and more marked acid phosphatase activity than those in group B. Although the rate of complete remissions (CR) obtained in both groups was similar (80% group A, 93% group B), marked differences were observed not only in the duration of CR but in the period of survival after CR as well, both factors being more prolonged in group B patients. 50% of patients with mediastinal involvement (group A) relapsed in the first 6 months of the evolution of the disease.

Adolescent↗
PubMed1978

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Adolescent↗
PubMed1978

Schooling, environment, and cognitive development: a cross-cultural study.

The purpose of this study was to investigate the influence of schooling and general environmental conditions on the development of memory and cognitive skills in young children. The subjects were 824 5- and 6-year-old children living in jungle villages and in slum settlements of Lima, Peru. Half of the children in both the jungle and city were Mestizo, and half were Quechua Indians. Some 6-year-olds of each cultural group and in each location attended school; others did not. Memory tasks were presented in different modes of representation, that is, verbal, pictorial, and enactive; and cognitive tasks in "concrete" and "abstract" versions. A sample of parents in each group was interviewed concerning environmental conditions. In addition, samples of upper-middle-class children in Lima and poor children in Detroit were tested to assess the generality of the findings. Attendance at school was related to improvement in performance on all tasks. Improvement was equivalent for both locations, both cultural groups, and each social class. Attendance at school also was accompanied by reduced within-group variability on some tasks and by greater differentiation of cognitive processes within children. Location and cultural group interacted differentially by task according to a complex pattern of relations. There were no indications that the organization of memory or cognitive processes differed as a function of social class, age, location, or cultural group. The results were interpreted in terms of children's opportunities to acquire specific memory and cognitive skills from schooling and from their general experience in a particular environment.

Age Factors↗
PubMedDate not supplied

Desquamation on taste buds.

Taste bud surface cells suffer from a desquamation process that modifies the pores' shape and size and the amount of amorphous substance in the pits region. We have studied this phenomenon-which probably plays an important functional role-by light, electron and scanning microscopy.

Animals↗