Topochemistry of blood cells of the Gallus domesticus (Aves, Galliforme).

Blood smears of both male and female chicken Gallus domesticus were analysed by using the following topochemical methods: a) Periodic acid-Schiff (PAS) for glycogen. b) Mercury-bromophenol blue for protein. c) O-Toluidine for myeloperoxidase. d) Sudan black B for lipid. The PAS reaction revealed glycogen in the cytoplasm of all thrombocytes and in a few heterophils. The presence of proteins was evidenced in all types of cells. However variation in the intensity of staining of protein granules was observed in the fusiform structures of the heterophils. A negative reaction for myeloperoxidase was found in all cells. Although some evidence of myeloperoxidase activity was show in the polymorphonuclears it was not enough to ascertain a positive reaction. Lipids were detected in the cytoplasm of few heterophils, eosinophils and monocytes.     

Genetic variation in the Bribri and Cabecar Amerindians from Talamanca, Costa Rica.

A screening of more than 40 loci was performed in the Bribri and Cabecar Amerindian populations of Talamanca in Southeastern Costa Rica. Some differences were found in the distribution (presence or absence) of the variants (some of them private) of the GOT, PEPA, RH, TF and TPI loci when the results reported here were compared with those of the Bribris and Cabecars that inhabit in the Pacific side of the country. Admixture with non-Indians was detected at the ABO, ADA, and G6PD loci. The proportion of polymorphic loci (P) found were 17.1 in the Bribris and 19.4 in the Cabecars; their average heterozygosites (H) estimates were 0.039 and 0.049 respectively. Fst values (0.019 in the Bribris and 0.056 in the Cabecars) seem to indicate that random events have played important roles in the divergence of the Cabecars. Low effective population sizes of the emigrant groups to the Pacific side and probable gene flow in the case of the Bribris, could be the cause of these differences.     

Small bowel and colon glucose absorption study in rats by an adaptation of Sols and Ponz method.

An adaptation of the Sols and Ponz method for the study of glucose intestinal absorption was developed by considering the special conditions of our line research. The glucose absorption was studied in proximal jejunum, distal ileum and distal colon in Wistar rat. The main adaptations in the method for successive absorptions with intestinal perfusions in vivo were the length of the intestinal segment and the change of the pumping system. The results are very similar to those obtained with the original method.     

L-thyroxine and L-triiodothyronine in the cerebral tissues of the adult rat. Effect of hypothyroidism]

The L-thyroxine and L-triiodothyronine concentrations in several brain areas (cerebral cortex, brain stem, hypothalamus, total brain and hypophysis) in normal and hypothyroid rats have been studied. Results show that L-thyroxine values at tissue level are inferior in the hypothyroid group, although non-significant with respect to the control group, whereas L-triiodothyronine presents values similar to the hypothyroid group and its control in all the brain regions studied with the exception of hypophysis. These results show that in hypothyroid situations exist a compensatory mechanism for maintaining the adequate L-triiodothyronine levels in several brain areas, although the serum levels are strongly decreased in hypothyroid animals.     

Effect of strontium and magnesium on blood calcium]

Twenty four male Wistar rats weighing 250 +/- 10 g, in three groups of 8 rats each, were used. Group A was used as control and the content of its drinking water was 6.5 mg/l Ca; 2.4 mg/l Mg. The drinking water of groups B and C was supplemented with 20 mM (SrCl2) and 20 mM (MgCl2), respectively. Once the 20 days of mineral supplementation had passed, arterial blood was extracted by puncture in the abdominal aorta. In the serum obtained after centrifugation, Ca, Mg, Sr and the total proteins (TP) were determined. Afterwards the serum was subjected to ultrafiltration. Concentrations of Ca, Mg and TP were measured in the obtained ultrafiltrates (u), with the above described techniques. The pH was measured before and after the ultrafiltration. The TP decreased significantly both in group B (supplemented with Sr), and in group C (supplement with Mg). Increases in Ca were found in group B and in Mg in group C. The Mg/Ca ratio increased 10% after the supplementation with Mg. At the ultrafiltrate a significant increase in Cau after supplementation with Sr and with Mg was observed. The Mgu/Cau ratio decreased 14% in the group supplemented with Sr and 38% after the supplementation with Mg. In conclusion, the supplementation with Sr (20 mM) in rats increases the Cau and could have the effect of reducing protein synthesis. These facts should be borne in mind when Sr is used for therapeutical purposes.     

Cellular and molecular mechanisms of aging: a review]

Since the beginning of this century, a large body of experimental data and observations accumulated concerning experimental and clinical gerontology. These data can be classified and analyzed according to the level of experimentation or observation as concerning aging at the molecular, cellular level or at higher levels of hierarchical organisation such as tissues, organs or the whole organism. Observations of these higher levels are mostly derived from epidemiological studies of human aging, horizontal studies or preferably vertical studies. The relative coherence of data collected at the molecular and cellular levels renders plausible a tentative of interpretation of aging phenomena at higher levels or hierarchical organisations from the tissues to the whole organism by using the data obtained at the molecular and cellular levels. The present article is a tentative for this kind or integrative interpretation of aging.