Evidence for the existence of protein inhibitors for S-adenosyl-L-methionine-mediated methylation of phosphatidylethanolamine in rat liver cytosol

The effect of rat liver cytosol on phosphatidylcholine biosynthesis via the N-methylation of phosphatidylethanolamine has been studied. The purified rat liver plasma membrane was used as an enzyme source. The rat liver 105,000 x g supernatant(cytosol) contained two different inhibitors for S-adenosyl-L-methionine-mediated methylation of phosphatidylethanolamine to phosphatidyl-N-mono-methylethanolamine. The inhibitors were inactivated by pretreatment with trypsin or heating at 96 degrees C, but were not inactivated by RNase. The inhibitors did not inhibit the synthesis of phosphatidylcholine from phosphatidyl-N-mono-methylethanolamine. The results indicate that two different protein inhibitors for methylation are present in rat liver cytosol fraction and that the inhibition by these proteins may have a role for the regulation of phosphatidylcholine synthesis in the plasma membrane.

Thyrotropin secretion in patients with hyperparathyroidism or hypoparathyroidism: effect of serum calcium on thyrotropin release

The influence of changes in the serum calcium concentration on TSH secretion was evaluated in patients with primary hyperparathyroidism and idiopathic hypoparathyroidism and in normal subjects. Serum calcium concentrations were 12.7 +/- 0.8, 9.0 +/- 0.4, and 5.7 +/- 0.5 mg/100 ml in hyperparathyroid, normal, and hypoparathyroid subjects, respectively, and were significantly different from each other. Serum T3 and T4 concentrations were comparable among the three groups. The basal serum TSH concentration was highest in hypoparathyroid, lowest in hyperparathyroid, and intermediate in normal subjects. However, all values were within normal limits and were not significantly different from each other. TRH-stimulated TSH secretion was significantly greater in hypoparathyroid patients and significantly less in hyperparathyroid patients than in normal subjects, respectively. The TSH response to TRH was normalized when the serum calcium concentration was normalized by parathyroidectomy in a hyperparathyroid patient or by 1 alpha-hydroxyvitamin D3 administration in a hypoparathyroid patient. To further clarify the mechanism responsible for the modified TSH response to TRH in the hypercalcemic state, rats were made chronically hypercalcemic by the administration of 1 alpha-hydroxyvitamin D3 (0.2 micrograms/100 g BW, ip, for 10 days) and 3% calcium chloride in drinking water. The pituitary TSH content of hypercalcemic rats was significantly greater than that of control rats. The results suggest that decreased TSH secretion produced by chronic hypercalcemia is due to diminished TSH release, rather than to decreased pituitary TSH reserve.

Monoamine oxidase inhibitory modulators in rat heart cytosol: evidence for induction by thyroid hormone

Inhibitory modulators of monoamine oxidase (MAO) were found in rat heart 105,000 X g supernatant. The modulators inhibited MAO activity present in the outer mitochondrial membrane. The inhibition was noncompetitive when using membrane-associated MAO as enzyme source. The modulators did not, however, inhibit the enzyme activity in the soluble fraction prepared from outer mitochondrial membranes. MAO inhibitory modulator concentration in rat heart cytosol was increased by the administration of T4 to rats. Three different inhibitory molecules were identified by gel filtration studies. These results suggest that thyroid hormone regulates membrane-associated MAO activity via the production of MAO inhibitory modulators, that the modulators probably bind to specific sites on the outer mitochondrial membrane, and that this binding of modulators to the membranes may result in a structural change in the mitochondrial membrane and a decrease in MAO enzyme activity.

An experimental asthma model in unanesthetized rat, and the difference in effect of disodium cromoglycate between passive cutaneous anaphylaxis model and asthma model in rat

We established here the experimental asthma model in unanesthetized rat, based on the observation of breathing. The effect of disodium cromoglycate (DSCG) was compared between the passive cutaneous anaphylaxis (PCA) model in rat and our experimental asthma model. The systemic anaphylaxis was elicited, in the rat passively sensitized with reaginic antibodies (reagin) against DNP-As, in response to challenge with antigen. The longer duration of expiration than that of inspiration was observed in the thoracic breathing of antigen-treated rats. The proportion of animals showing this respiratory distress in thoracic breathing (RDTB) was related to the concentration of antiserum used for the sensitization. The relation between RDTB and the concentration of antiserum was more manifest when the degree of RDTB was considered as a score. Inhibition of DSCG was dose-dependent on RDTB and reagin-induced PCA at more than 1 mg/kg. The maximal inhibition of DSCG (20 mg/kg, i.v.) on RDTB or PCA was observed when it was given 30 s before the challenge with antigen. The effect on RDTB decreased gradually with time after dose, and lasted beyond 60 min similar to the inhibitory activity of DSCG on antigen-induced asthmatic reaction in patients. Whereas, the effect on PCA decreased rapidly, and disappeared within 30 min after dose. These results indicate that RDTB is a principal indicator of respiratory distress induced by reagin, and that the effect of DSCG in asthmatics may be explained by its inhibitory activity on RDTB rather than that on PCA.

A screening test to identify aldosterone-producing adenoma by measuring plasma renin activity. Results in hypertensive patients

In an attempt to devise a screening test for aldosterone-producing adenoma (APA) among hypertensive patients, the serum sodium and potassium levels, plasma renin activity (PRA), plasma aldosterone concentration, and aldosterone-PRA ratio were measured in 348 patients with hypertension. Nine patients with a substantially elevated aldosterone-PRA ratio were selected and hospitalized for further investigations. All nine patients were then recognized by scintigraphy with labeled cholesterol, venography, and surgical excision as having APA. The serum concentration of potassium was subnormal in three of nine patients with APA. In patients with APA, administration of diuretics and salt restriction significantly elevated PRA. However, even under notable diurnal and day-to-day variations of plasma aldosterone concentrations, the aldosterone-PRA ratio was always elevated inappropriately (more than 400) in patients with APA. In contrast, after administration of diuretics, both the PRA and aldosterone levels increased significantly in patients with essential hypertension, but the aldosterone-PRA ratio was less than 200. Since the renin-angiotensin system seems to be a major factor controlling aldosterone secretion in normal subjects, it is suggested that an elevation of aldosterone-PRA ratio more than 400 is a useful screening tool for the prediction of APA among hypertensive patients.

Mitotic index in gastric carcinoma of the scirrhous type

For the purpose of studying the clinical and pathological specificities of the scirrhous type in gastric carcinoma, 96 patients with gastric carcinoma were studied according to age, sex, stage, macroscopic types and mitotic index. Scirrhous carcinoma was diagnosed in 45 patients. There were higher incidences of scirrhous carcinoma in the younger generation and among women. In the scirrhous type, the percentage of stages III and IV was higher than that of stages I and II (p less than 0.005). In Borrmann's categories III and IV, patients with the scirrhous type were more numerous than those with the other types. Mitotic indices were 18.4 +/- 8.1 in scirrhous type, 52.8 +/- 13.5 in medullary type, 54.1 +/- 16.9 in intermediate type and 53.3 +/- 11.5 in non-cancerous gastric mucosa. The low rate of mitotic index in those with scirrhous carcinoma was statistically significant compared to those of other types and that of the non-cancerous gastric mucosa (P less than 0.001). Mitotic index is apparently related to the extent and the degree of degeneration of interstitial connective tissue. The speed of the growth of the tumor mass in gastric carcinoma is not so closely related to the mitotic index, and relates to a greater extent the number of dissociated cells entering the digestive canal.

Coincidence of neurofibromatosis and myotonic dystrophy in a kindred

Neurofibromatosis and myotonic dystrophy have occurred in ten members of a nonconsanguineous family with a high degree of concordance. The expression of neurofibromatosis is peripheral, and the expression of myotonic dystrophy has produced at least moderately severe disability. Neither disease has appeared to alter the phenotypic expression of the other when both have occurred simultaneously. Secretor typing supports the assumption that the myotonic dystrophy in this family is the commonly recognised secretor-linked entity. The segregation pattern of the two disorders in this family suggest the possibility of close linkage between the loci for neurofibromatosis and myotonic dystrophy.

Changes in endocrine activities relative to obesity in patients with essential hypertension

The possible role of obesity in the development of hypertension was investigated in two study groups. In a population study of 961 subjects, 739 were found to be normotensive and 222 hypertensive. The prevalence of hypertension was 18.7 percent in the nonobese, and 33.2 percent in the obese subjects. Systolic and diastolic blood pressures increased progressively with the increase of relative body weight in both normotensive and hypertensive subjects. In addition, an endocrinologic study was made of 97 patients with essential hypertension; in 82, plasma renin activity (PRA) was inversely correlated with the increase of relative body weight but not with urinary Na excretion. Despite this decrease of PRA, the level of serum aldosterone was not influenced by relative body weight. Thus, the aldosterone/PRA ratio ratio increased progressively with the increase of relative body weight. Thiazide therapy normalized this inappropriately high ratio, and reduced body weight and blood pressure. Restriction of dietary calories and salt intake had a similar effect. With a high-salt intake in an obese subject, the aldosterone/PRA ratio is unduly increased. Apparently aldosterone contributes to the additional retention of sodium and water and thereby promotes hypertension in the presence of an expanded fluid volume.

Chorea gravidarum. Report of a fatal case with neuropathological observations

In a 23-year-old primigravida with no prior history of rheumatic fever, choreiform movements developed late in the third trimester, and she died in a state of hyperthermia 14 days later. Results of neuropathological examination showed, as the basis for the chorea, nerve cell loss and astrocytosis within the striatum (especially the caudate nucleus). Anaylsis of the case in conjunction with a review of the literature strongly suggests that chorea gravidarum should be regarded as a syndrome rather than a specific disease entity.

Heat stroke. Report of three fatal cases with emphasis on findings in skeletal muscle

Three fatal cases of heat stroke were encountered in the central New York area over a two-month period. Although in each instance one or more predisposing factors were identified, exertion clearly played a role in its development in only one case. In addition to laboratory and postmortem findings indicative of dysfunction of many organ systems, there was morphological evidence of widespread damage to skeletal muscle.