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Biomedical subjects

M Marques

Publications and source records attributed to M Marques.

At least 55 records · Page 3Linked to original sources
PubMed1985

Effects of thyroid hormones on the hippocampal glial cells of fasting rats.

The effects of the oral administration of thyroid hormones on the hippocampal glial cells in fasting or fed adult rats were studied. The hormone treatment and/or fasting were done during two periods of five days interpolated by ten days without any hormone treatment or fasting. Prominent histological changes and increased number of glial cells were observed in the hippocampus of rats when the thyroid hormone administration was associated with fasting.

Animals↗
PubMed1984

Insulin binding sites and action in the adrenal glands from normal and streptozotocin diabetic rats.

Insulin binding to rat adrenal glands was studied in vivo by i.v. injection of 125I-insulin either alone or together with an excess of unlabelled hormones (insulin, glucagon, prolactin, or growth hormone). In addition, isolated glands from normal or streptozotocin diabetic rats (STZ) were incubated in vitro with 125I-insulin and varying concentrations of unlabelled insulin. Both experiments showed specific binding sites in the adrenal glands. Furthermore the glands from diabetic rats bound more insulin than the glands from controls. The insulin stimulatory effect on the deoxyglucose (14C-DG) uptake was examined in isolated glands from normal and STZ rats. Adrenal glands from control rats exhibited higher basal values of 14C-DG uptake than glands from STZ rats. Insulin induced a stimulatory effect on the 14C-DG transport in glands from both control and diabetic rats. Adrenal glands from STZ rats responded much earlier to exogenous insulin, however the maximal stimulating concentration of the hormone did not restore the 14C-DG uptake to control values. The lowest concentration of insulin that increased the 14C-DG transport was 3 X 10(-8) M. The adrenal gland must be considered a target organ for insulin by both criteria, insulin specific binding and stimulatory action on the deoxyglucose transport.

Adrenal Glands↗
PubMed1984

In vivo specific uptake of labeled insulin by turtle (Chrysemys dorbigni) thyroid gland.

Insulin labeled with 125I was injected into turtles to study its specific uptake by the thyroid gland. The gel filtration behavior of labeled material in blood and thyroid gland was determined in order to ascertain if the uptake is specific. Most animals were pretreated with KI to saturate the gland with iodide. Maximum specific uptake of radioactivity by the thyroid gland was only detected in animals pretreated with KI. A significant dose-related reduction (ED50 = 0.5 micrograms/kg) was observed when unlabeled insulin was administered simultaneously with 125I-insulin. Prolactin, glucagon and growth hormone (2 mg/kg) did not affect 125I-insulin uptake. Most of the radioactive material extracted from the turtle thyroid 15 min after 125I-insulin injection coeluted with 125I-insulin on Sephadex G-50. This peak decreased as a function of time after 125I-insulin administration. Similar elution patterns were found for thyroid extracts from turtles previously treated with KI. The labeled hormone in the gland was rapidly degraded or processed to both higher and lower molecular weight compounds. Prior administration of KI suppressed the former, whereas when unlabeled insulin was injected simultaneously with 125I-insulin the amount of degradation products was reduced. The demonstration of radioactive degradation products is consistent with the intracellular receptor-mediated degradation hypothesis. These findings indicate the presence of specific insulin-binding sites in the thyroid gland.

Animals↗
PubMed1984

Sex differences of normal dogs in lipid mobilization and blood glucose levels after glucose or insulin infusion.

The influence of sex hormones on carbohydrate and lipid homeostasis was studied by comparing the response to glucose or insulin infusion in male and female dogs. The levels of blood glucose, serum immunoreactive insulin (IRI) and plasma free fatty acids (FFA) were determined. The hyperglycemia induced by glucose infusion (10 mg min-1 kg-1) for 60 min in summer was significantly higher in male than in female dogs. This sex difference in the response was confirmed in experiments performed in winter, when blood glucose levels of both sexes in response to the infusion reached higher values than those found in summer. The increase of serum IRI in response to glucose infusion was similar in both sexes in the summer experiment, while in winter the increase was significantly reduced and delayed in males. Glucose infusion into male and female dogs induced no significant changes in plasma FFA concentration in experiments carried out in winter or summer. Insulin infusion (16.6 mU min-1 kg-1) caused hypoglycemia in both sexes, which was of earlier onset in the females. The antilipolytic effect of insulin occurred in both sexes and was also stronger in females. The data show sexual and seasonal differences in response by dogs to glucose infusion and emphasize the participation of sex hormones in the homeostasis of energy substrates.

Animals↗
PubMed1980

ABO aggulutinins from Biomphalari straminea snails.

Extracts from B. straminea spawn are active against A and B normal red cells. A1 and A2 subgroups may be differentiated with trypsin-, papain- and pronase-treated cells. 0 cells treated with papain, pronase and neuraminidase react weakly to the extracts.

ABO Blood-Group System↗
PubMed1980

Agglutinins and hemolysins from Biomphalaria tenagophila snails.

A saline anti-A and incomplete anti-A,B agglutinin were found in spawn extracts of Biomphalaria tenagophila snails. Significance differences after papain and pronase treatments were also found for A1 and A2 subgroups. The hemolysin titers are high, and unspecific.

ABO Blood-Group System↗