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Biomedical subjects

M Burgos

Publications and source records attributed to M Burgos.

52 records · Page 3Linked to original sources
PubMed1990

Synaptonemal complex analysis in Talpa occidentalis spermatocytes (Insectivora, Mammalia). II. Evolution of the X-chromosome self-pairing process.

Zygotene and pachytene configurations of the X chromosome were studied in whole-mount, silver-stained preparations of spermatocytes from XY males from a population of Talpa occidentalis in which sex reversal has been described. The most striking finding in this study was a self-pairing conformation of the axial (differential) element of the X chromosome. This self-pairing was markedly constant in the site of initiation, which invariably involved the distal free end of the X and the region beyond the X-Y pairing segment, so that X-Y synapsis was never disturbed. In addition, self-pairing occurred later than autosomal synapsis and was accompanied by thickening of the axes, although this seemed to occur after the formation of an ordinary synaptonemal complex. The etiology of this phenomenon may be based on residual homology, possibly due to conservation of a primitive isochromosome throughout the karyotypic evolution of this species. However, the possible relationship between self-pairing and sex reversal remains obscure.

Animals↗
PubMed1990

Effect of supplementing cardioplegic solution with deferoxamine on reperfused human myocardium.

Fourteen randomized patients undergoing myocardial revascularization were divided into group A standard hypothermic cardioplegic solution) and group B (the same cardioplegic solution supplemented with deferoxamine 1000 mg/L). In all patients myocardial biopsy specimens were obtained before ischemia and during reperfusion and were assessed for chemiluminescence (to indirectly determine oxygen-free radical activity) and for electron microscopic studies. Chemiluminescence in group A showed a photoemission of 36.5 +/- 1.5 cpm/mg protein X10(-3) for the preischemia samples and 72 +/- 5.7 cpm/mg protein X10(-3) for the reperfusion samples (p less than 0.01). In the patients who received deferoxime (group B), values for chemiluminescence for preischemia and reperfusion samples were not significantly different. Electron microscopic studies showed a significant increase in grade 4 (severely damaged) mitochondria in reperfusion biopsy specimens from both groups as compared with preischemia samples. However, reperfusion samples from group B showed a better preservation of myocardial cells with marked reduction of grade 4 (severely damaged) mitochondria. These results support the hypothesis that oxygen-free radicals are responsible in part for the production of reperfusion injury in the human heart. They suggest that this mechanism may be at least partially controlled by adding an iron chelating agent such as deferoxime.

Cardioplegic Solutions↗
PubMed1989

Reduction of reperfusion injury with mannitol cardioplegia.

Forty consecutive patients undergoing myocardial revascularization were divided into two equal groups: group 1 received standard cardioplegic solution, and group 2 received a solution containing mannitol, 59.8 mmol/L. In 6 patients in each group, myocardial biopsies were done before ischemia and at the time of reperfusion. Samples were assessed by chemiluminescence to determine oxidative stress and by electron microscopic studies. A significant reduction in atrial arrhythmias was observed in the mannitol group. Chemiluminescence in group 1 showed a photoemission of 37.6 +/- 3.5 cpm/mg of protein x 10(-3) for the preischemia samples and 74.8 +/- 16 cpm/mg of protein x 10(-3) for the reperfusion samples (p less than 0.001). In group 2, the values for chemiluminescence were 37.7 +/- 3.4 cpm/mg of protein x 10(-3) and 40 +/- 6.1 cpm/mg of protein x 10(-3), respectively (p = not significant). Electron microscopic studies showed, for group 1, increased grades of damaged mitochondria in the reperfusion biopsy specimens compared with the preischemia biopsy specimens (p less than 0.01). In group 2, differences for damaged mitochondria were not significant. These results support the hypothesis that mannitol reperfusate significantly reduces myocardial damage in patients undergoing open heart procedures. They also suggest that this protective effect may be in part secondary to the antioxidant property of mannitol, although other mechanisms may have accounted for or contributed to the improved outcome after ischemia.

Biopsy↗
PubMed1988

A study of the Ag-staining significance in mitotic NOR's.

The biological significance of nucleoli and mitotic Ag-staining NOR's has been the cause of controversy for several years. Whereas several authors state or assume a direct correlation between transcriptional activity and Ag-staining, others deny this hypothesis or claim a correlation between Ag-staining and decondensation of the NOR chromatin. Our results show that a decondensed state of the NOR chromatin is necessary but not sufficient to permit silver impregnation, allowing us to conclude that transcriptional NOR activity in the previous interphase is additionally required for silver staining.

Animals↗
PubMed1988

Comparative study of G- and C-banded chromosomes of five species of Microtidae: a chromosomal evolution analysis.

G-banded karyotypes were compared in the following species of Microtidae: Microtus nivalis, M. cabrerae, M. arvalis, and Arvicola sapidus. Previous observations on A. sapidus and A. terrestris were also incorporated in this study. The results show that Robertsonian translocations and pericentric inversions are common mechanisms involved in the karyotypic evolution of this group. Interspecific differences on the G-banding patterns were also analysed, and an attempt was made to establish a presumptive phylogenetic tree.

Animals↗
PubMed1988

Heterogeneous heterochromatin and size variation in the sex chromosomes of Microtus cabrerae.

The sex chromosomes of Microtus cabrerae are characterized by large segments of constitutive heterochromatin in both the X and Y. Alkali treatment, enzymatic digestion (trypsin), and fluorochrome staining reveal considerable heterogeneity within these heterochromatic blocks and allow us to distinguish several regions. In addition, variation in the length of these segments is also present, probably as a result of deletions. A possible explanation for the origin of these heterochromatic blocks is discussed.

Animals↗
PubMed1988

XY females in Microtus cabrerae (Rodentia, Microtidae): a case of possibly Y-linked sex reversal.

Microtus cabrerae is a species with blocks of heterochromatin on both sex chromosomes. Polymorphism caused by extensive deletions affecting these heterochromatic segments exists in both X and Y chromosomes. Of a total of 22 males and 22 females studied, four females exhibited sex pair dimorphism similar to that observed in males. C-banding techniques and preliminary data regarding inheritance support the hypothesis that these specimens are XY fertile females and that this sex reversion is most likely inherited through the Y chromosome of these females.

Animals↗
PubMed1986

Trends and differentials in dietary patterns and nutrient intake among migrant Puerto Rican families.

Preoccupation to define the nutritional status of Puerto Rican families migrating to the United States, motivated the present research. A total of 526 families residing in the South Bronx, New York, and four communities in Puerto Rico, were therefore studied. Results in regard to nutrient intake suggest that the mothers' diets appear to be adequate in the South Bronx as well as in Puerto Rico, except in iron consumption, in the latter. Furthermore, the data show an apparent tendency to overconsumption of certain foods in both the South Bronx and Puerto Rico, particularly of the protein group, as well as a high consumption of sugar and carbonated beverages in Puerto Rico. Dietary data were corroborated through nutritional anthropometry, conforming a tendency for overweight and obesity among the women studied. Detailed information on the dietary changes occurred during the last five years, is provided. Educational programs such as EFNEP, availability of new foods, and the food preferences of children in their homes, seem to be influencing factors in the dynamics of food modifications within societal groups in transition.

Body Weight↗
PubMed1979

[Ultrastructure of the liver in patients with cholesterol stones receiving chenodesoxycholic acid (author's transl)].

The ultrastructure of the liver was investigated in 5 normal persons and 10 patients with cholesterol stones. In the patients numerous intramitochondrial crystals could be found; precipitated cholesterol-digitonin complexes were found as well in the canaliculi, the sinus and the pericanalicular areas. 5 patients received chenodesoxycholic acid (10 mg/kg/day); liver biopsies taken 3 and 6 months after start of treatment did not show any more the changes described above.

Chenodeoxycholic Acid↗
PubMedDate not supplied

Changes in the epididymal ultrastructure in hypothyroid rats.

The purpose of this research was to investigate the effect of hypothyroidism on the ultrastructure of the rat cauda epididymis. Thyroidectomy was obtained by i.p. injection of 270 microCi of 131I per rat. One month later, several portions of cauda epididymis were examined in an electron microscope. Morphological and physiological differences were detected in the cauda epididymis of the hypothyroid animals when compared to the control normal rats. The hypothyroid condition was associated with a decrease in the height of the cells and diminution of the internal lumen, number of mitoses, and chromatin decondensation. Hypothyroidism produces a remarkable impairment of epididymal morphology that could be mainly responsible for the functional alterations that lead to the dramatic slowing of spermatozoa motility, commonly seen in severe thyroid insufficiency.

Animals↗
PubMedDate not supplied

[Epizootic outbreaks of trichinosis in 2 pig farms from the Metropolitan Region of Chile].

In Chile swine trichinosis has presented a progressive decreasing in the last two decades of XX century. T. spiralis pig infection descended from an average of 0.683 per 1000 in 1980-1984 to 0.315 in 1985-1989 and to 0.115 in 1990-1996. In the particular case of Metropolitan Region this decreasing has been more marked: from an average of 0.058 per 1000 in 1990-1994 to 0.003 in 1995-1999. Between the end of June 1999 and middle January 2000 in Metropolitan Region abattoirs T. spiralis was detected in 15 (4.9%) out of 306 swine from two pigsties located in El Monte (E.M.) and Padre Hurtado (P.H.) 45 and 30 km south-west from Santiago. In the same period another four pigs from the same premises were found infected in abattoirs of other regions. During inspection visits it was stated that both pig farms had deficient sanitary conditions. Phototrichinoscopy was positive in three out of five Rattus norvegicus collected in E.M. In pigsty PH the examination of diaphragm samples of 25 dogs and 17 cats resulted negative. In the premises originating T. spirali infected swine the Metropolitan Environmental Health Service Abattoirs Program carries out an epidemiological vigilance consisting in the follow-up of animals destined for slaughtering in order to initiate prophylactic actions oriented to eliminate eventual sources of trichinosis infection for human and rearing pigs.

Abattoirs↗