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Biomedical subjects

Y Oka

Publications and source records attributed to Y Oka.

At least 595 records · Page 33Linked to original sources
PubMed1980

Clinical and hormonal aspects of the watery diarrhea-hypokalemia-achlorhydria (WDHA) syndrome due to vasoactive intestinal polypeptide (VIP)-producing tumor.

Three patients with the watery diarrhea-hypokalemia-achlorhydria (WDHA) syndrome were studied. All had watery diarrhea, hypokalemia and hypercalcemia. Plasma vasoactive intestinal polypeptide (VIP) levels determined by radioimmunoassay were markedly elevated in these patients, indicating that they had VIP-producing tumors. Plasma VIP levels determined serially after the operation indicate that its determination is useful in estimating the effect of a treatment. As for multiple endocrine neoplasia type 1 (MEN1), two out of the three cases belonged to this category. Patient 1 had a brother with insulinoma, and in case 2, even though there was no family history, the autopsy revealed not only multiple tumors of the pancreas but also pituitary adenomas, chief cell hyperplasia of the parathyroid glands, thyroid adenomas and adrenocortical adenomas. VIP and other hormones in the tumors as well as in the plasma were examined extensively in these cases. In case 1, VIP, gastrin and calcitonin were produced in the tumor and only plasma VIP levels were elevated. In case 2, with multiple tumors, tumor 1 produced VIP, glucagon pancreatic polypeptide, gastrin and calcitonin, and tumor 2, VIP, pancreatic polypeptide, gastrin and beta-melanocyte stimulating hormone. In this case, plasma VIP, pancreatic polypeptide and glucagon levels were elevated. In case 3, VIP and calcitonin were produced in the tumor, and plasma VIP and calcitonin levels were elevated. These results indicate that (1) VIP is a good tumor marker for the WDHA syndrome due to VIP-producing tumors; (2) patients with the WDHA syndrome are sometimes associated with MEN1; and (3) VIP-producing tumors are multiple hormone-producing tumors, and VIP predominantly elevated in the plasma results in the WDHA syndrome, although other hormones such as pancreatic polypeptide, glucagon and calcitonin are sometimes found to be elevated in plasma without contributing to the clinical features.

Achlorhydria↗
PubMed1980

A decreased response of cyclic adenosine monophosphate concentrations to glucagon in liver slices from streptozotocin-induced diabetic rats.

Responses to glucagon from the adenylate cyclasecyclic adenosine monophosphate (cAMP) system in liver slices from control and streptozotocin-induced diabetic rats were compared. Tissue cAMP levels were similar in the basal state but responded poorly to glucagon (20 pg/ml-2 microgram/ml) in diabetic rats. Insulin treatment of diabetic rats in vivo led to a reversal of the glucagon stimulation towards the values in the control rats. The basal and glucagon-stimulated activities of adenylate cyclase in crude membrane fractions were similar in both groups. Plasma immunoreactive glucagon levels in diabetic rats were approximately three times higher than those in normal rats. Liver slices obtained from normal rats, which were injected with glucagon (0.2 mg, i.m.) 45 min previously, also showed an impaired responsiveness to glucagon of tissue cAMP levels, while no significant difference in adenylate cyclase activity was observed between the normal and glucagon-treated rats. These results suggest that the responsiveness of liver slices from the streptozotocin-induced diabetic rat has been modified by the preceding hyperglucagonemia. The reason for the observed differences between slices and crude membranes is not known.

Animals↗
PubMed1980

Pulsatile cardiopulmonary bypass: failure to influence hemodynamics or hormones.

In a randomized trial of pulsatile vs nonpulsatile cardiopulmonary bypass for coronary artery surgery, we studied hemodynamic and hormonal responses. Anesthesia did not produce a response but, from the time of the incision, cortisol and antidiuretic hormone levels and plasma renin activity all increased. Cortisol levels continued to rise after surgery, whereas the other began to fall. Systemic vascular resistance fell dramatically during cardiopulmonary bypass but rapidly rose after bypass with a reciprocal change in cardiac index. We did not see the changes ascribed to nonpulsatile bypass by others. There ws no difference between our pulsatile and nonpulsatile cases. High-flow cardiopulmonary bypass, vasodilating inhalation anesthesia and continuation of Inderal therapy may account for our results.

Body Temperature↗
PubMed1980

Hemodynamic performance of the Ionescu-Shiley valve prosthesis.

The hemodynamic performance of the Ionescu-Shiley bovine heterograft valve has been evaluated by intraoperative measurement of transvalvular gradients and cardiac outputs. Effective orifice areas (EOAs) were calculated and the data compared to those obtained by other investigators for other prostheses. In the aortic position, each valve, from 19 to 31 mm external diameter, produced a pressure gradient; mean EOA increased with increasing valve size, so that small (19 to 23 mm) valves were moderately stenotic and larger valves were only mildly stenotic. The presence of a mitral prosthesis produced larger transaortic valve gradients, probably as a result of aortic outflow obstruction by the mitral prosthesis. The Ionescu valve appears to be hemodynamically superior to other biological valves in the aortic position and comparable to most mechanical prostheses, although the data for comparison are scant. Each mitral valve produced a pressure gradient and, on the average, larger (29 mm) valves performed no better than smaller (25 mm). Mean EOAs for each valve size (25 to 29 mm) were adequate to provide satisfactory hemodynamics comparable to other available prosthetic valves. Mild obstruction of the left ventricular outflow by the prosthetic struts was seen to be related to the distance between ventricular septum and the struts. Most currently available prostheses seem to provide similar hemodynamics in the mitral position, and considerations such as thrombogenicity and durability may be relatively more important in the choice of a mitral valve substitute than in the choice of an aortic valve substitute.

Aortic Valve↗
PubMed1979

Metabolic acidosis in patients receiving anticonvulsants.

Blood pH, bicarbonate, PCO2, serum calcium, alkaline phosphatase and red cell carbonic anhydrase were measured in 37 selected patients receiving anticonvulsants. Patients with metabolic acidosis showed a high incidence of hypocalcemia with increased alkaline phosphatase and a significant reduction of carbonic anhydrase-B activity. High iPTH levels were found in 13 patients, but this was not correlated with acid-base balance status. Anticonvulsant drugs seemed to inactive carbonic anhydrase-B activity. Metabolic acidosis might be one of the factors causing a disturbance of calcium metabolism in these patients.

Acidosis↗
PubMed1979

beta-Blockade therapy for supraventricular tachyarrhythmias after coronary surgery: a propranolol withdrawal syndrome?

A high incidence of cardiac arrhythmias and hypertension has been noted after coronary artery bypass surgery in patients previously treated with oral propranolol. Forty-two patients undergoing coronary bypass surgery had propranolol withdrawal 10 hours before surgery and were randomized into a group treated with propranolol immediately postoperatively, and a nontreatment group. Patients treated with prophylactic propranolol had a significantly lower incidence of postoperative supraventricular arrhythmias compared to patints who received no prophylaxis. All the arrhythmias responded rapidly to 1 mg of intravenous propranolol therapy, whether it was used as a primary treatment or as a supplement to prophylactic propranolol. The findings suggest that (1) there is a high incidence of supraventricular arrhythmias and sinus tachycardia after coronary artery bypass which might reflect an abrupt propranolol withdrawal, and (2) that perioperative prophylactic or supplementary propranolol therapy will successfully prevent or treat most of these arrhythmias.

Coronary Artery Bypass↗
PubMed1978

Glucose-6-phosphatase activity in liver and blood platelets of two patients with glycogen storage disease type I.

Glucose-6-phosphatase (G-6-Pase) activity in liver and blood platelets of two patients with glycogen storage disease (GSD) type I is described. Both patients had a reduced activity of G-6-Pase in liver. The km value for glucose 6-phosphate (G-6-P) of residual activity in liver of both patients was similar to that of control liver. We could not demonstrate any reduced activity of platelet G-6-Pase in the patients. Platelet G-6-Pase with our assay method seems to represent a nonspecific phosphatase activity. Our observation suggests that it is necessary to examine platelet G-6-Pase of many other patients with GSD type I to confirm that G-6-Pase deficiency can be diagnosed by enzyme assay performed on blood platelets.

Alanine↗
PubMed1978

Methylmalonic acidemia.

A patient presenting with severe metabolic acidosis accompanied by hyperglycinemia, hyperuricemia, hypoglycemia and hypertammonemia is described. Metabolic acidosis was found to be due to accumulated methylmalonic acid and did not respond to vitamin B12 administration. The patient showed favorable growth and development when kept on a low isoleucine, methionine, threonine and valine diet. In vitro studies using a lymphoid cell line derived from the patient showed a deficiency of methylmalonyl-CoA carbonyl-mutase.

Acidosis↗