Biomedical subjects
Publications and source records attributed to E Rasio.
Forty male patients with a prolactinoma were operated on by the transsphenoidal approach. Postoperative normalization of PRL levels occurred in 37% of the cases, in 100% of the microadenomas and 68% of the adenomas with preoperative PRL levels below 700 ng/ml. None of the invasive tumors were normalized. Partial hormonal deficits were produced by surgery in three cases and panhypopituitarism in one case.
Fifteen male patients with prolactin-secreting pituitary adenomas were studied before and after transsphenoidal microsurgical treatment. Loss of libido and sexual impotence were the most frequent symptoms, being present in 12. Visual defects were present in seven patients, gynecomastia was observed in four and galactorrhea was noted in three. Most of the tumours were large; only one was a microadenoma. Four patients were cured by the operation. In all the other patients the plasma levels of prolactin were significantly lowered and the visual defects corrected or lessened, but sexual impotence was not modified. No important deficiency of the pituitary gland was induced by the operation. The results indicate that in males loss of libido and sexual impotence are frequent and early manifestations of prolactinomas, and that transsphenoidal resection is a safe therapeutic approach.
Over 15 yr, 24 patients underwent transsphenoidal pituitary surgery for Cushing's disease with a median follow-up of 12 months. Cures included 7 patients with normal sella turcicas (6 microadenomas), 6 patients with focal depressions (6 microadenomas) of the sella (grade I), and 3 patients (3 adenomas) with enlarged sellas (grade II). Three patients with sella destruction (grades III and IV), 2 with normal sellas, and 1 with focal sella depression (grade I) were not cured. Two apparent cures (microadenomas) recurred. Tumor histology revealed 19 basophilic adenomas; electron microscopy (14 tumors) and immunochemical studies (10 tumors) revealed only ACTH cells. Circadian rhythm returned in 6 cured patients. Impotence (in 2), amenorrhea (in 7), and galactorrhea (in 3) resolved in affected cured patients. The major surgical complication was hemorrhage at the operative site (3 patients). Transsphenoidal pituitary surgery is a valuable method for managing Cushing's disease in many patients.
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Among 42 patients with GD, one had clinical diabetes and 10 had chemical diabetes (26%) when tested by OGTT. The insulinogenic index was lower in patients with chemical diabetes than in patients with normal OGTT. Among 19 patients with isolated hypogonadotropic hypogonadism, similarly tested, three had chemical diabetes (15%). In a prospective study of 29 patients with GD tested repeatedly, the incidence of diabetic OGTT increased significantly with age. As glucose tolerance deteriorated, the plasma insulin response was delayed and the insulinogenic index decreased. The carbohydrate tolerance was unrelated to weight, estrogen replacement therapy, chromosomal pattern, and GH response. In six GD cases studied at a 6 year interval, the tolerance to oral glucose decreased with time whereas glucose utilization following its intravenous injection or tolbutamide administration was only slightly diminished; the plasma insulin was reduced by approximately 50% in response to each of these stimulations. These studies suggest that carbohydrate intolerance is frequently associated with GD and is due to a diminished beta-cell function.
Glucose is the major energetic substrate of blood capillary endothelium; aerobic glycolysis is quantitatively the most important pathway. Insulin has no direct effect on glucose utilization. The glucokinase activity of the capillary endothelium is undetectable and the plasma cell membrane is freely permeable to glucose. All pathways of glucose utilization are stimulated by a high ambient glucose concentration: intracellular sorbitol accumulation and glucose-carbon incorporation into basement membrane collagen are most sensitive to the glucose effect. During chronic hyperglycemia, the amino acid composition of the basement membrane is modified and its capacity to incorporate glucose is enhanced. The glucose induced alterations of the blood capillary metabolism may contribute to the development of the diabetic microangiopathy.
On the basis of results obtained from an oral glucose tolerance test, (OGTT), twenty patients with gonadal dysgenesis were classified as normal (N = 8) and diabetic (N = 12). The two groups of patients were further tested by a rapid intravenous glucose injection, a tolbutamide test, an insulin sensitivity test and an oral amino acid load. Fasting levels of plasma growth hormone (GH) were normal in all subjects but one. Approximately 1/3 of the GH responses during testing periods were abnormal, being either absent during hypoglycaemia or following amino acid ingestion, or paradoxically increased during hyperglycaemia. No correlation was found between the degree of carbohydrate intolerance and the levels of plasma GH. There was no gross alteration of tissue sensitivity to exogenous insulin. The beta-cell response to tolbutamide, amino acid and intravenous glucose were comparable in patients with a normal or a diabetic OGTT. In both groups, the rates of decrease of blood glucose following tolbutamide or intravenous glucose were also similar and within the normal range. During OGTT, the diabetic group had a delayed insulin release and a low insulinogenic index. It is concluded that in gonadal dysgenesis the intolerance to an oral carbohydrate load is frequently associated with, but unrelated to, anomalies of the GH secretion. In diabetic subjects, the process of insulin secretion loses its normal sensitivity to the oral glucose stimulus while remaining unaltered and similiar to that of non-diabetic subjects in response to tolbutamide, amino acid and intravenous glucose.
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An unusual case of insulinoma in a 51-year-old man demonstrates the difficulties in diagnosing and treating hypoglycemia. From the many laboratory tests and procedures performed, the only findings typical of insulinoma were inappropriate values of plasma immunoreactive insulin in relation to the corresponding values of blood glucose, and these were sporadic. A small beta-cell adenoma in the pancreatic head was the cause of the hypoglycemia.
The rete mirabile of the eel swimbladder is a vascular organ in which arterial andvenous capillaries alternate in regular fashion. The endothelium of the arterial capillaries is high, whereas that of the venous capillaries is thin and fenestrated. Endothelial cells and pericytes are the only cells found in the rete. A tubular systemin the arterial endothelial cells is connected with the organelles. The basal laminaeof both capillaries are similiar to those of mammalian capillaries of the same type. They present three layers of different electron density and have a high fibrillar pattern.A fine fibrillar material and dense fibrils appear in the cisternae of the rough endoplasmic reticulum and in large vacuoles of endothelial cells and pericytes: these cells areapparently involved in the synthesis of their lamina. Since the rete mirable ofthe eel swimbladder is a pure vascular preparation, it is most useful for the study of themorphology, the permeability, and the metabolism of the endothelial cells and for the analysis of the chemical structure of their basil laminae.
Large amounts of basal laminae material can be extracted by sonic disruption from the capillary tissue of the rete mirabile of the eel swimbladder. The extracted basil laminae material has the same fibrillar pattern as that found in the intact tissue. Thechemical composition is similiar to that of other basil laminae isolated from tissues inmammals, with high content of glycine, proline, hydroxyproline, lysine, and hydroxylysine. The mono- and disaccharide units linked to the hydroxylysine are also present. Of all the pathways of glucose utilization, the 'C-glucose incorporation into the basallamina glycoproteins is the most sensitive to the medium glucose concentration. The glucosyltransferase activity seems stimulated to a plateau value of saturation when the medium glucose concentration is raised from 5 to 20 mm. The 'C-labeled amino acid incorporation into the basal laminae glycoproteins is not affected bythe medium glucose concentration. The results obtained in this study allow for a hypothesis which links the biochemical, morphologic, and functional properties of various typesof basal laminae in normal and hyperglycemic conditions.
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