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Biomedical subjects

M Freire

Publications and source records attributed to M Freire.

60 records · Page 4Linked to original sources
PubMed1978

Effects of dark rearing on dendritic spines in layer IV of the mouse visual cortex. A quantitative electron microscopical study.

The effect of visual deprivation on dendritic spines in the visual cortex layer IV of 19 days old mice was studied with the electron microscopy. From the serial ultrathin sections of the selected dendrites bearing spines the author has calculated the volume and surface area of dendritic spines, and also the surface area of their synaptic zones. Employing statistical methods he has demonstrated that visual deprivation produced a retarded development of some dendritic spines in dark reared mice. The fact that the smallest dendritic spines cannot be seen with the light microscope while the number of such small spines is larger in the dark reared mice can well explain the apparent reduction in the number of dendritic spines in deprived animals studied in Golgi impregnated material.

Animals↗
PubMed1978

[Purification and properties of beta-N-acetylglucosaminidase from Mytilus edulis L. gonads (author's transl)].

beta-N-Acetylglucosaminidase (beta-2-acetamido-2-deoxy-D-glucoside acetamidodeoxyglucohydrolase EC 3.2.1.30) from Mytilus edulis gonads and a homogenous protein was obtained from it by ion-exchange chromatography, gel filtration and disc electrophoresis. The apparent molecular weight, determined by gel filtration was 140,000 +/- 5,000. Two subunits were identified. The molecular weights of both subunits calculated by disc-electrophoresis were 70,000 and 75,000 + 2,000. Maximal activity for pH was 4.2. At 50 degrees C the enzyme was still active; at 60 degrees C inactive. The values of the apparent Km's proved to be 0.57 mM and 0.076 mM for p-nitrophenyl-beta-D-N-acetylglucosaminide and p-nitrophenyl-beta-D-N-acetylgalactosaminide as substrates. In the incubation of the enzyme with hyaluronic acid, chitin, deacetilated glycol-chitin and p-nitrophenyl-beta-D-glucuronide, N-acetyl-beta-D-glucosamine and glucuronic acid were not liberated. N-acetylgluconolactone and N-acetylgalactonolactone are competitive inhibitors for the enzyme.

Acetylglucosaminidase↗
PubMedDate not supplied

Visceral leishmaniasis in a new ecological niche near a major metropolitan area of Brazil.

In 1991, a community cross-sectional study was conducted in a village situated near the beach and close to Salvador, the capital city of Bahia, in Brazil, to determine the prevalence of visceral leishmaniasis since 1989. A serological survey was made of human and canine reservoirs and an intradermal skin test for leishmaniasis was used to assess cellular immune responses. Nearly 30% of the 243 individuals in the study area had positive skin tests and 14% had positive serology, the latter being compatible with recent infection; 29 of 460 dogs examined were seropositive. A possible association was observed between human infection and the presence of dogs in or near residences, but not between human infection and malnutrition. This report describes the evolution of a new focus of visceral leishmaniasis, its expansion toward a metropolitan area, and current measures taken to control the epidemic.

Adolescent↗
PubMedDate not supplied

On-line echocardiographic assessment of hemodynamic indexes by an adaptive Doppler analysis algorithm and signal/noise ratio calculation.

Assessment of cardiac diseases commonly involves the use of spectral Doppler echocardiography. Its use, however, often requires manual digitization of various transvalvular flow profiles. A new approach has been developed for on-line analysis of Doppler data, which involves thresholding based on the signal/noise ratio, calculating instantaneous values, and plotting on the spectral display in real time. We examined the reliability of this new method in 32 patients with 59 various flow jets by comparing it with the data derived by manual analysis. Correlations between the algorithm analysis and manual analysis for peak velocity, peak gradient, velocity-time integral, and acceleration time were excellent. These indexes were obtained with the algorithm in a shorter time and with better reproducibility than with manual analysis. Thus this new adaptive Doppler analysis algorithm yields reliable on-line quantification of valuable hemodynamic variables and represents an advance in quantitative echocardiography.

Algorithms↗