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Biomedical subjects

H Sakuma

Publications and source records attributed to H Sakuma.

At least 253 records · Page 14Linked to original sources
PubMed1979

Effect of tolbutamide on plasma catecholamine in insulin dependent diabetics.

In 4 cases of insulin dependent diabetics, blood levels of glucose, C-peptide reactivity (CPR), free fatty acid, and catecholamines were followed after the intravenous tolbutamide response test. Plasma CPR was low and did not respond to tolbutamide injection, and blood levels of glucose and free fatty acid did not change during the test. Fifteen min after the tolbutamide injection, plasma epinephrine plus norepinephrine and norepinephrine levels fell to 87.5% and 67.4% of the initial values, respectively. These results suggest that decrease in the blood glucose and free fatty acid levels usually observed after tolbutamide injection is not the direct action of drug, but is secondary to insulin secretion, and tolbutamide-induced decrease in catecholamines may contribute to the secretion of insulin from the pancreatic beta-cells.

Catecholamines↗
PubMed1978

Exocytosis plays an important role in catecholamine secretion from human pheochromocytoma.

Plasma dopamine beta-hydroxylase (DBY) activity, urinary catecholamine (CA) and vanillylmandelic acid (VMA) were studied pre- and postoperatively in 20 patients with pheochromocytoma. Preoperative plasma DBH activities were distributed widely, ranging from normal to very high; the mean value of DBH as well as urinary CA and VMA was significantly greater than that of normal subjects. Postoperative falls of plasma DBH activity, of urinary CA and of VMA were by 76%, 96% and 83% of the preoperative level, respectively. Significant correlations were observed between postoperative falls of individual DBH activities, urinary VMA and weight of the tumors, whereas there was correlation neither between preoperative DBH activity and urinary CA, nor between the rate of postoperative falls of these respective values. These findings suggest that pheochromocytoma is capable of secreting DBH, and wide variations in the rate of DBH output from these tumors may account for varying capacity of CA biosynthesis in the tumor. Further, it may be concluded that the process of exocytosis plays an important role in the mode of CA secretion by these tumors, although secretion through diffusion may be operating as well.

Adolescent↗
PubMed1978

Plasma noradrenaline concentrations and haemodynamics in the early stage of essential hypertension.

1. Plasma noradrenaline concentrations and haemodynamic status were simultaneously studied in young patients with uncomplicated essential hypertension and in age-matched normal controls. 2. Resting plasma noradrenaline in the controls tended to increase slightly, but progressively, with age. The hypertensive subjects had significantly higher plasma noradrenaline concentrations than those in the controls, but these values did not show any age-related variation. The response of plasma noradrenaline to the standing position tended to increase with age in the controls, whereas plasma noradrenaline in the hypertensive subjects showed a wide range of responses without any fixed relationship with age. 3. The cardiac index was significantly greater in the labile hypertensive subjects than in the controls, whereas total peripheral resistance was significantly greater in the sustained hypertensive subjects than in the labile patients and in the controls. Mean arterial pressure in these patients was closely related with the value of total peripheral resistance rather than with the cardiac index. 4. Of the patients with raised plasma noradrenaline 80% showed significantly increased values of either total peripheral resistance or cardiac index. Plasma noradrenaline was correlated significantly to total peripheral resistance, and marginally to mean arterial pressure. 5. These findings support the view that sympathetic nervous overactivity is an important factor underlying the haemodynamic findings in these patients.

Adolescent↗
PubMed1978

Interference with fluorimetric assay of catecholamine by labetalol.

Influence of labetalol and 5-(1-hydroxy-2-aminoethyl)salicylamide (SA), a part of the chemical structure of labetalol, on the fluorimetric assay of catecholamine (CA) was studied. Both labetalol and SA have a weak but significant fluorescence which is indistinguishable from that of CA with peaks of excitation/emission wavelengths at 410/490. It is thus concluded that an apparent increase in urinary CA observed in patients receiving labetalol is caused by the contamination of labetalol and/or its metabolite, and that the evaluation of urinary CA in hypertensive patients must be done prior to the use of labetalol to avoid any confusion in diagnosis of pheochromocytoma.

Drug Interactions↗
PubMed1976

Plasma catecholamine levels in the coronary sinus, aorta and femoral vein of subjects undergoing cardiac catheterization at rest and during exercise.

Plasma catecholamine (CA) levels in the coronary sinus (CS), aorta (Ao) and femoral vein (fv) were simultaneously measured in 22 patients with various heart diseases at rest and during handgrip exercise (IHG). The mean resting levels of plasma norepinephine (NE) in CS, Ao and FV were 359 +/- 49 (SEM) pg/ml, 290 +/- 27 and 234 +/- 24, respectively. The corresponding values of epinephrine (E) were 127 +/- 18 pg/ml, 186+/- 30 and 97 +/- 11, respectively. The E values in Ao were significantly greater than those in CS and in FV (p less than 0.05). IHG exercise induced an obvious elevation of plasma CA levels in every portion of the circulation studied. The mean increments of NE concentration were 81%, 54% and 67% of the resting levels at CS, Ao and FV, respectively, while IHG induced elevation of E were 70% of the resting values at each portion studied. Significant correlations were observed between individual CA concentrations in CS and in Ao, and also between those in Ao and in FV at rest. Under raised sympathoadrenal conditions, however, individual values of NE in CS failed to correlate signficantly to those in Ao and in FV, respectively. The NE output from CS was limited to only 3% and 5% of those in Ao at rest and during IHG, respectively. An actual mean increment of NE on its passing through the coronary circulation was only 2% or less of NE output in ao at both stages. It appears, thus, to be untenable that the cardiac tissue is one of the major source of circulating CA at physiological condition. From these reasons, the direct measurement of NE levels in CS may be mandatory, when plasma CA assay is designed for the purpose of studying the role of the sympathetic nerve activity in the regulation of cardiac function.

Adolescent↗
PubMed1975

High epinephrine content in the adrenal tumors from Sipple's syndrome.

Percent of epinephrine content to total catecholamine is low in pheochromocytomas irrespective of unilateral or bilateral adrenal origin when they have no medullary carcinoma of the thyroid. However, epinephrine content higher than norepinephrine has been noted in the adrenal tumors from the patients with Sipple's syndrome. Although an exact reason for this remained unknown, our data could suggest that the adrenal tumors in Sipple's syndrome are primarily different from other types of pheochromocytoma, and thorough examinations for detecting the thyroid carcinoma should be necessary when the adrenal tumor is rich in epinephrine.

Adolescent↗
PubMed1975

Pheochromocytomas occurring in 3 members in a family.

Three members of a kindred exhibiting bilateral adrenal pheochromocytomas are presented together with previously reported 15 familial cases in Japan. The rate of tumor growth, the stage of asymptomatic or chemical pheochromocytoma and the importance of urinary catecholamine assay for detection and diagnosis in this type of tumor are particularly emphasized.

Adrenal Gland Neoplasms↗