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Biomedical subjects

M C Rodríguez

Publications and source records attributed to M C Rodríguez.

50 records · Page 3Linked to original sources
PubMed1991

Age structure and abundance levels in the entomological evaluation of an insecticide used in the control of Anopheles albimanus in southern Mexico.

Applications of bendiocarb produced a high insecticidal residual effect lasting up to 3 months on the most common indoor house surfaces. No significant decreases in mosquito man-biting rate levels were observed between treated and untreated villages. It was shown that almost equal proportions of intra- and peridomicillary mosquitoes came into contact with the insecticide, indicating that mosquitoes commonly enter houses, rest on treated surfaces and return to bite both indoors and outdoors. Although the insecticide was found to have a significant effect on the percentage parity (interpreted as abundance of older individuals) of intra- and peridomicillary Anopheles albimanus mosquitoes, parity recovered and continued a normal cyclic pattern that appeared to be dependent on relative abundance. The proximity of a treated village to an untreated village (1.2 km) can affect the age structure of mosquito populations through shared common resting and breeding sites.

Age Factors↗
PubMed1989

Annual changes in the number, testosterone content and ultrastructure of glandular tissue cells of the testis in the marbled newt Triturus marmoratus.

The testes of 8 specimens of Triturus marmoratus were collected during each month of 1987 and processed for electron microscopy and light microscopy demonstration of testosterone (T) following the ABC (avidin-biotin peroxidase complex) method. According to their staining affinity for anti-T antibodies, the glandular tissue cells were classified as T-, T+, T++, and T and the annual changes in the numbers of these cell populations, as well as in the volume occupied by the glandular tissue, were calculated. The volume occupied by the glandular tissue increases from September to December; it begins to decrease in April and disappears from June to August. The glandular tissue is formed from the interstitial cells that surround the lobules containing differentiating germ cells. During the spermatogenic process, the interstitial cells do not show staining affinity for anti-T antibodies. In August-September, the interstitial cells around the lobules that have completed spermatogenesis become positively stained (T+) and form the glandular tissue when the spermatozoa leave the testis. The numbers of intensely stained cells in the glandular tissue (T++ and T ) increase from September to November; begin to decrease in December; disappear in January-February; increase again in March and decrease again in April until they disappear in June-September. The interstitial cells, before their transformation in glandular tissue, are ultrastructurally similar to fibroblasts. After their transformation these cells increase in size and develop abundant smooth endoplasmic reticulum, mitochondria with tubular cristae and lipid droplets. This morphological pattern is maintained in the glandular tissue from September to April in spite of the changes in staining affinity during this period.

Animals↗
PubMed1988

Changes in surface area and number of Leydig cells in relation to the 6 stages of the cycle of the human seminiferous epithelium.

In order to evaluate the occurrence of a Leydig cell cycle related to the cycle of the seminiferous epithelium in man, the numbers of peritubular Leydig cells and surface area of these cells along 1 mm of tubular basement membrane at each stage of the cycle were calculated on histological sections of young adult testes. The Leydig cells that were located separated from the tubules (perivascular Leydig cells) were also classified according to the stage of the cycle shown by the nearest seminiferous tubule; the surface area and number of these cells were also calculated. The total surface area and numbers of Leydig cells (peritubular plus perivascular) along 1 mm of tubular basement membrane did not change during the cycle of the seminiferous epithelium. Both the surface area and the numbers of peritubular Leydig cells were greater in stages I and II of the cycle, when spermatozoa are released; they decreased in stages III and IV and increased again in stages V and VI, whereas the contrary occurred in perivascular Leydig cells. The average surface area of each Leydig cell type remained constant throughout the stages of the cycle.

Adult↗
PubMed1988

[Effect of corticosteroids, quinacrine and L-652, 731 on experimental aggregation of polymorphonuclear leukocytes induced by complement and platelet activating factor (PAF)].

The effects of 6-methylprednisolone sodium succinate, quinacrine and the synthetic anti-PAF compound L-652,731 were studied on the PAF and complement induced aggregation of rabbit polymorphonuclear leukocytes in vivo. High doses (100-250 mg/kg) of corticosteroid were able to abrogate PAF and complement induced aggregation. Quinacrine (1.25 mg/kg), and L-652,731, partially precluded complement-depending aggregation. The L-652,731 dose employed was just enough to prevent PAF induced aggregation. These results suggest that in those pathological conditions in which polymorphonuclear aggregation occurs, factors other than those derived from plasmatic complement system activation, and laboring jointly with it, may be involved.

Agranulocytosis↗
PubMed1988

Paper chromatographic characterization of an extracellular biologically active compound from Coelastrum sphaericum var. dilatatum.

A non-cytotoxic, wide antiviral spectra compound was isolated from the lyophilized media of axenic cultures of the green alga Coelastrum sphaericum var. dilatatum. After acid hydrolysis, polyenic-like fractions were liberated from the same compound with inhibitory effect against Candida albicans. Biochromatographic and spectrophotometric results demonstrated that the product included a glycosidic fraction associated with a nucleotidic component.

Antifungal Agents↗
PubMed1987

Quantification of cell types throughout the cycle of the human seminiferous epithelium and their DNA content. A new approach to the spermatogonial stem cell in man.

The numbers of each different cell type in the human seminiferous epithelium were determined throughout the 6 stages of the cycle in both semithin and ultrathin sections obtained from 15 young adult men with normal testicular histology. Up to 4 types of A spermatogonia (Ad, Ap, Al and Ac) were distinguished. In addition, the DNA nuclear content of seminiferous epithelium cells was determined on Feulgen-stained sections. Both Ad and Ap spermatogonia showed a 2c DNA content and were present in the 6 stages of the cycle, though their numbers decreased in stages III-V. Both Al and Ac spermatogonia showed a DNA content varying from 2c to 4c. Al spermatogonia were observed in stages III-V; their numbers plus those of Ad spermatogonia in these stages were similar to the numbers of Ad spermatogonia in the other stages lacking in Al spermatogonia. Ac spermatogonia appeared in stages III-VI and their numbers plus those of Ap spermatogonia in stages III-V were similar to the numbers of Ap spermatogonia in the other stages lacking in Ac spermatogonia. The results suggest that Ad spermatogonia are the stem cells. Some of them replicate their DNA; during this replication they appeared as Al spermatogonia. Al spermatogonia divide, giving rise to both Ad and Ap spermatogonia. Some Ap spermatogonia replicate their DNA; during this process they are transformed into Ac spermatogonia which divide, giving rise to B spermatogonia.

Adult↗
PubMed1987

Changes in the lipid inclusion/Sertoli cell cytoplasm area ratio during the cycle of the human seminiferous epithelium.

The area occupied by Sertoli cell lipid inclusions--electron-lucent lipid vacuoles (LLV) and electron-dense lipid droplets (DLD)--at each stage of the cycle of the seminiferous epithelium was measured on electron micrographs in young adults and elderly men, and expressed as the ratio "area occupied by lipid inclusions/area occupied by the Sertoli cell cytoplasm". For LLV this ratio increased from stage I to stage III, and decreased from stage IV to stage VI in young adults. These results suggest that the development of LLV is synchronized with the spermatogenic process: the residual bodies released in stages I and II are phagocytized by Sertoli cells and transformed into LLV; the amounts of LLV decrease in the subsequent stages of the cycle and increase again when new residual bodies appear. In elderly men the ratio LLV/Sertoli cell cytoplasm was 1.9-2.9 times higher than in young adults at each stage of the cycle. This increase may be related to the increased germ-cell degeneration observed in ageing testes, DLD were less abundant than LLV and the DLD/Sertoli cell cytoplasm ratio did not undergo cyclic changes in young adults or elderly men.

Adult↗
PubMed1986

Ultrastructural observations on nucleoli and related structures during human spermatogenesis.

The ultrastructural study of nucleoli and ribonucleoprotein-containing structures in human seminiferous tubules revealed that the nucleoli of spermatogonia, spermatocytes and Sertoli cells exhibited a tripartite structure consisting of: a fibrillar center, a compact granular portion, and a reticular portion containing both pars fibrosa and pars granulosa. The nucleoli of primary spermatocytes showed a developed reticular portion. At pachytene, the compact granular portion enlarged and lost its connection with the fibrillar center and the reticular portion which decreased in size. This suggests a nucleolar segregation similar to that of ovocytes in many species. Two similar developmental stages of nucleoli were observed in spermatogonia. In addition to nucleoli, there were other ribonucleoprotein-containing structures such as intranuclear closely-packed granules in Ap spermatogonia, coarse granules in the chromatin rarefaction zone of Ad spermatogonia, the nuage and Lubarsch crystals of spermatogonia, the chromatoid body of spermatids, the annulate lamellae of both spermatids and Sertoli cells, and many structures of the spermatid neck region.

Adult↗
PubMed1986

Quantitative differences between variants of A spermatogonia in man.

The area of cytoplasm, nucleus, nucleolus and mitochondria, as well as the elongation and irregular outline of the nucleus were determined, on electron micrographs by using an image analyser, for Ap (pale), Ad (dark with intranuclear vacuole), Ad-like (dark without intranuclear vacuole), Ac (cloudy) and Al (long) human spermatogonia. Ap and Ac spermatogonia had larger nucleus, larger nucleolus, and more cytoplasm than did Ad, Ad-like, and Al spermatogonia. In addition, the nuclei of Ap and Ac spermatogonia were more spherical and had a more distinct outline.

Adult↗
PubMedDate not supplied

[Smoking prevention in the school: results of a 3-year program].

Tobacco use poses one of the greatest health problems at school. Its prevention through health education should be assumed up by all members of the school community and health personnel (especially family and respiratory physicians). We designed an anti-tobacco program lasting three years aimed at all the students of the 6th, 7th and 8th grades at school as well as those in the pre-university years that was implemented in a rural area. This study reports the results of the attitudes of the 610 students (256 boys and 354 girls, between 11 and 20 years old) collected at the end of the program. 59.4% of the boys and 44.1% of the girls reported having smoked on some occasion. The mean age at the time of the first contact with tobacco was 11.8 +/- 2.4 years, this being significantly different between the boys and the girls. The main reasons for starting to smoke tobacco were quoted as peer pressure (57.1%) and curiosity (55.5%). That their parents smoked was only adduced as a reason by 29.5% of the students. Knowledge of the harmful effects of tobacco was limited and only 57% related tobacco smoking to lung cancer and only 41% to coronary pathology. At the end of the program 13.6% of the students involved smoked. 93.9% of those who quit smoking related this event to the program. Of those still smoking, 63.6% said they would like to quit. This justifies the need to reinforce the knowledge that will allow them to switch attitudes and stop smoking. Intervention programs in school populations have proved to be useful in the struggle to decrease smoking among school children. If an adolescent can avoid smoking it is likely that s/he will not smoke in adulthood. It is necessary to further develop this type of anti-tobacco program as reflected in this paper.

Adolescent↗
PubMedDate not supplied

Nuclear bodies (sphaeridia) in Sertoli cells of a man with acquired immunodeficiency syndrome (AIDS) and testicular infection by cytomegalovirus.

Histological and ultrastructural study of an adult man with acquired immunodeficiency syndrome (AIDS) revealed multiple testicular lesions. The seminiferous tubules varied from dilated tubules with hypospermatogenesis, to tubules with Sertoli cells and a few spermatogonia, to necrotic tubules. The testicular interstitium showed abundant inflammatory infiltrates, some of them forming microabscesses. The Sertoli cells exhibited spherical intranuclear inclusions corresponding to both cytomegalovirus and sphaeridia. Some sphaeridia stained intensely with EDTA as granular and fibrillar portions of the nucleolus; however, many sphaeridia stained weakly as nucleolar fibrillar centers. These observations suggest that a Sertoli cell response to cytomegalovirus is the proliferation of nucleolar organizing centers that in some instances may transform to give rise to more or less abnormally developed nucleoli.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

[Surgery of the subthalamic nucleus in Parkinson's disease].

INTRODUCTION AND DEVELOPMENT: The subthalamic nucleus (STN) plays a crucial part in the pathophysiology of Parkinsonism. Its inactivation improves all the main signs and symptoms of Parkinson's disease. Surgery of the STN in patients with the disease is effective and the benefit/risk relationship very favorable. Although the dyskinesias are not a definite limitation, it seems most reasonable to use techniques of deep cerebral stimulation until greater experience has been obtained with subthalamotomy. The long term efficacy is being studied and preliminary data indicate that the clinical benefit obtained is maintained in the long term. CONCLUSIONS: More studies are necessary to determine the mechanism of action of surgery on the STN. The potential neuroprotector effect of subthalamic surgery requires more extensive study.

Humans↗
PubMedDate not supplied

[Adrenal transplantation and Parkinson's disease].

Although substantial therapeutic advances have been developed during the last decade, L-dopa remains as the most successful treatment for Parkinson's disease. However, about 80% of the patients show motor and psychiatric complications after several years of levodopa treatment. Thus, new therapeutic approaches have been undertaken during the last decade in order obtain a better control of the motor symptoms. Adrenal medullar grafts into caudate nucleus and/or putamen have been widely studied as a new therapeutic strategy. They have been undertaken in more than 300 parkinsonian patients and the general finding is that adrenal medullar grafts induce a significant improvement of motor symptoms which remain 1 year after the surgery. The mechanisms by which they can elicit a motor improvement are not well understood since chromaffin cells do not survive in the host brain after transplantation as demonstrated by PET scan studies. The present work summarizes the results found by different authors as well as the mechanisms involved in the motor improvement observed in these patients.

Adrenal Medulla↗