Biomedical subjects
Publications and source records attributed to W Nitiyanant.
A 20-year-old male presented with a small hydrocoele in the left scrotal sac, bilateral small testes, and azoospermia with normal secondary sexual characteristics. Chromosome study revealed 46,XY. The results of hormonal and histopathological studies were consistent with Sertoli-cell-only syndrome.
Complete heart block developed in a 29-year-old man with hyperthyroidism and acute febrile illness. The definite cause of acute febrile illness was unknown. The results of bacteriological and viral studies were negative. Endomyocardial biopsy revealed no evidence of carditis which is the common cause of heart block. All the abnormalities resolved completely after the fever subsided and the patient was treated with an antithyroid drug. Available information indicates that a high degree of heart block can sometimes occur in hyperthyroidism in either the presence or absence of additional factors which can independently impair atrioventricular conduction. This course of events which occurred in this patient suggest that complete heartblock may have been the direct manifestation of the hyperthyroid state, however, the acute febrile illness may have been an aggravating factor in the development of abnormal atrioventricular conduction.
We investigated the relation between fibrocalculous pancreatic diabetes and cassava consumption in a case-control study, in which 31 cases of pancreatic diabetes were compared with 45 non-diabetic control subjects who had no pancreatic calcification. Risk of diabetes was not related to cassava consumption. We also observed no increased risk of fibrocalculous pancreatic diabetes associated with alcohol consumption, history of gallbladder and biliary tract diseases, ascariasis, and family history of diabetes. Lower monthly income, farmer occupation, rural residence, and low BMI were significantly (p less than 0.05) related to pancreatic diabetes. Our data suggest that consumption of cassava may not be an important risk factor for pancreatic diabetes. With limited sample size, however, cassava consumption could not be excluded as one possible cause of fibrocalculous pancreatic diabetes.
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Serum C-peptide levels were measured during a glucagon stimulation test in ten normal nonobese controls and 54 diabetic patients with recent onset of diabetes under 30 years of age. Diabetic patients were comprised of 13 CTPD, 23 IDDM, and 18 NIDDM. As similar to IDDM patients, serum C-peptide concentrations did not rise significantly (P greater than 0.05) in response to glucagon administration in CTPD-patients. Mean baseline and peak serum C-peptide concentrations in CTPD-patients were significantly lower (P less than 0.001) than the values in normal controls and NIDDM patients, but were significantly higher (P less than 0.05) than those in IDDM patients. We conclude that CTPD patients have partial C-peptide reserve, which may protect against ketosis and contribute to ketosis resistance in CTPD. Our results also suggest that CTPD patients require insulin treatment. Neither baseline nor peak C-peptide levels after glucagon could discriminate CTPD from IDDM and CTPD from NIDDM.
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A calcium infusion (4 mg Ca++/kg/hr) significantly increased plasma insulin levels and reduced blood glucose in 4 patients with insulin-secreting pancreatic islet cell tumors. These parameters were not altered by a similar infusion of calcium in normal volunteers, 2 patients with alimentary hypoglycemia, and 2 with functional hypoglycemia. No difference in response was observed between patients with benign and malignant beta-cell tumors. Infusion of diazoxide (600 mg) with calcium blocked the stimulation of the latter on insulin secretion. The results indicate the usefulness of calcium infusion in the diagnosis of insulin-secreting tumor.
To characterize further the nature and site of the receptor for the IgG stimulator in Graves' disease, we have developed a preparative scheme to provide a bovine thyroid subfraction rich in plasma membranes. Pellets (800 X g) obtained from bovine thyroid homogenates were layered on a 30-64% continuous sucrose gradient (SG). The centrifuged gradient was divided into four portions (SG1, 2, 3, and 4); and these along with the 800 X g pellet were characterized in terms of their capacity to neutralize (bind) the biological activity of LATS, their specific binding of [125I]TSH, and their subcellular marker content. Subfraction SG1 contained the highest adenyl cyclase specific activity, the highest [125I]TSH binding specific activity, and vied with the 800 X g pellet and SG3 for the highest specific activity of LATS neutralization. Electron microscopy of SG1 showed a predominance of plasma membrane structures contaminated with a modest amount of cellular debris. Adenyl cyclase activity in SG1 was enhanced by TSH, LATS, and sodium fluoride. Although a dose-response curve could be established for TSH, a similar relationship could not be established for LATS. We conclude that activation of plasma membrane-bound adenyl cyclase is associated with neutralization of the biological activity of LATS. Further, the difference between [125I]TSH binding and LATS neutralization activity observed in the various thyroid membrane subfractions suggests that either LATS and TSH interact at different sites or have different mechanisms of binding at a common site.