Jiro Endo

Studies on ectopic ACTH‐producing tumors. II. Clinical and biochemical features of 30 cases

This report describes the clinical and biochemical features of 30 cases of ectopic ACTH‐producing tumors diagnosed by the detection of ACTH in the tumor tissues. Several uncommon tumors, such as tumors of the esophagus, stomach, and larynx, were included in this series. None of the patients with bronchogenic carcinoma showed signs of classical Cushings syndrome, whereas 7 of the remaining 13 patients with other tumors were Cushingoid in appearance. Adrenocortical hyperfunction was present in 61% at the first examination and developed during the course of the disease in 18% more. In the remaining patients (21%), adrenocortical function remained within normal limits. These results indicate that there exist ectopic ACTH‐producing tumors without clinical and biochemical sequelae of excess hormone. In some of the tumor extracts studied, MSH and CRF‐like activities and serotonin were detected. This suggests that multiple hormone production is not uncommon in ectopic ACTH‐producing tumors.

Angiotensin II and phorbol ester enhance isoproterenol- and vasoactive intestinal peptide (VIP)-induced cyclic AMP accumulation in vascular smooth muscle cells

The importance of Ca2+ and cAMP in the regulation of cellular functions has been well demonstrated. We studied the effect of angiotensin II (AII), a potent Ca2+-mobilizing hormone, on cAMP accumulation induced by isoproterenol (ISO) and vasoactive intestinal peptide (VIP) in cultured vascular smooth muscle cells (VSMC). Although the addition of AII alone caused little increase of cAMP, it enhanced ISO- and VIP-induced cAMP accumulations in a dose-dependent manner. This enhancement was mimicked by tumor-promoting phorbol ester but not by Ca2+ ionophore. This observation suggested that AII enhanced agonist-induced cAMP accumulation through the activation of protein kinase C in VSMC.

Blood pressure cosegregates with a microsatellite of angiotensin I converting enzyme (ACE) in F2 generation from a cross between original normotensive Wistar-Kyoto rat (WKY) and stroke-prone spontaneously hypertensive rat (SHRSP).

We investigated the linkage between high blood pressure and the ACE gene in the F2 generation between SHRSP/Izm and WKY/Izm. The male F2 rats were categorized into 3 genotypes according to a microsatellite polymorphism in the ACE gene. Significantly high blood pressure was observed in the SHRSP homozygotes when it was compared to the blood pressure of the heterozygotes. Further, after 2 or 3 months salt-loading, the blood pressure was significantly higher in the SHRSP homozygotes than in the heterozygotes and the WKY homozygotes. The heterozygotes had a blood pressure similar to that in the WKY homozygotes, indicating that the effect of the ACE gene genotype was recessive. Salt appetite was neither correlated with the salt-sensitivity nor cosegregated with the ACE genotype. The results indicate that the locus of ACE gene associates with the development of hypertension, especially salt-sensitive hypertension.

Phorbol 12-myristate 13-acetate prevents isoproterenol-induced morphological change in cultured vascular smooth muscle cells

The effect of phorbol 12-myristate 13-acetate (PMA) on isoproterenol (ISO)- and dibutyryl cAMP (dBcAMP)-induced morphological change and cytoskeletal reorganization was studied in cultured vascular smooth muscle cells (VSMC) using the fluorescence staining of actin and microtubules. The treatment of VSMC with 1.0 microM of ISO or with 1.0 mM of dBcAMP for 90 min induced the disruption of actin-containing stress fibers followed by cytoplasmic arborization. The addition of 100 or 10 nM of PMA prevented both the destruction of actin fibers and cell arborization induced either by ISO or by dBcAMP. However, PMA rather enhanced cAMP production stimulated by ISO. 1-Oleoyl-2-acetyl-sn-glycerol (100 micrograms/ml) mimicked this inhibitory effect of PMA whereas 4 alpha-phorbol 12,13-didecanoate (100 nM) failed to block the arborization. These results indicated that the inhibition of arborization by PMA was mediated through the activation of protein kinase C. Colchicine at 5.0 microM also had an inhibitory effect on ISO- and dBcAMP-induced cell arborization. However, immunofluorescence studies revealed that colchicine but not PMA elicited the reorganization of microtubules, suggesting that the effect of PMA was mediated through a mechanism different from that of colchicine. These observations indicated that the morphology of VSMC was regulated through the alteration of cytoskeletal organization induced by cAMP-mediated and by protein kinase C-dependent systems.

Coimmobilized enzyme columns in determining serum creatinine using creatininase, creatinase and sarcosine oxidase by flow-injection analysis and chemiluminescence detection

Abstract A coimmobilized creatininase-creatinase-sarcosine oxidase column was used to determine creatinine in serum by flow injection with chemiluminescence detection, based on the chemiluminometric rate assay of hydrogen peroxide produced from creatinine by consecutive reactions of three immobilized enzymes. The procedure is independent of the concentration of endogeneous creatine in serum, although creatininase catalyses the reversible reaction. Further, because of the shifts of pH optima caused by immobilization of the three enzymes, successive reactions could be carried out under almost optimum conditions at pH 8.5. The method was found to give perfect calibration linearity, with accurate recoveries ranging from 97 to 101% for up to 1.0 mM creatinine. The within-day and day-to-day relative standard deviations (n = 10) were 2.4% and 3.7%, respectively, for 0.10 mM creatinine and 1.6% and 2.1%, respectively, for 0.96 mM creatinine. The results correlated satisfactorily with those obtained by the modified Jaffe reaction rate method.

Effects of chronic bromocriptine-induced hypoprolactinemia on plasma testosterone responses to human chorionic gonadotropin stimulation in normal men

To study the role played by normal levels of plasma prolactin (PRL) in the secretion of testosterone (T) in the testes, we induced hypoprolactinemia with a daily dose of 5 mg bromocriptine administered orally in five normal men 20 to 35 years of age for 8 weeks. The basal PRL, T, luteinizing hormone, follicle-stimulating hormone, and maximum responses of plasma T to human chorionic gonadotropin (hCG) stimulation were measured every 2 weeks. Basal levels of plasma T were reduced in the 1st 2-week-long period of hypoprolactinemia. In the 4-week-long period of hypoprolactinemia, the maximal response of plasma T to hCG stimulation was significantly reduced. The findings suggest that normal levels of plasma PRL may play an important role in the secretion of T in the human testes in vivo.

Use of various types of column reactors for flow-injection analysis

Two or three different kinds of immobilized enzymes can be aligned in a minireactor so that sequential enzymatic reactions are carried out from upstream to downstream during flow-injection analysis. A lactate oxidase-catalase reactor, used as precolumn for removing pre-existing lactate in serum before the lactose dehydrogenase (LDH) reactions, was useful for the determination of serum LDH activity, which did not require any blank correction. A sequential glutamate dehydrogenase-glutamate oxidase reactor was also useful for a novel chemiluminometric determination of ammonia. On the other hand, a co-immobilized creatininase-creatinase-sarcosine oxidase reactor, in spite of containing creatininase which catalyses the reversible reaction, was the most efficient for the determination of serum creatinine.

Influence of chronic hyperprolactinemia induced by sulpiride on the hypothalamo-pituitary-testicular axis in normal men

For elucidation of the effects of hyperprolactinemia on the hypothalamic-pituitary-testicular axis, five healthy men were exposed to sulpiride (300 mg/day by mouth); four among the five maintained hyperprolactinemia (71.6 to 95.3 ng/ml) for 78 days. Clomiphene citrate (CC), luteinizing hormone (LH)-releasing hormone, and human chorionic gonadotropin tests were performed before and after sulpiride treatment. The CC test, given as a measure of hypothalamic function, was carried out in each of the five volunteers before sulpiride treatment (control) and on days 14 (2 weeks) and 60 (2 months) of sulpiride administration. Each value of plasma LH stimulated by CC was integrated and expressed as a ratio of the integrated value obtained after administering CC at 2 weeks and 2 months to that from each control experiment. The mean ratio in the four subjects at 2 months (mean +/- standard deviation, 0.769 +/- 0.121) was significantly lower than that at 2 weeks (0.942 +/- 0.073; P less than 0.05) and before sulpiride treatment (1.000; P less than 0.01). Impairment of LH responses to CC by 2-month long sulpiride-induced hyperprolactinemia suggests that chronic hyperprolactinemia in men partly suppresses LH secretion by its inhibitory action on the hypothalamus.

Application of immobilized enzymes to clinical analyses : use of co-immobilized glucose oxidase and peroxidase in column form

Glucose oxidase from Aspergillus niger and peroxidase from horseradish were simultaneously immobilized onto alkylamine glass beads which were then packed into a 1.5 x 20 mm column and integrated in the flow system of an AutoAnalyzer I. Glucose in serum, up to 5.0 g/l, was continuously determined at a rate of 60 samples per hour. The co-immobilized enzyme column gave better sensitivity as compared with an enzyme column which contained a mixture of two kinds of individually immobilized enzymes. The enzyme column was sufficiently stable while in use for two months. The results correlated satisfactorily well with those obtained by other well established methods for glucose assay.

Potassium accelerates urinary sodium excretion during salt loading without stimulating atrial natriuretic polypeptide secretion.

1. Effects of potassium (K) supplementation (100 mEq/day) on urinary sodium (Na) excretion and on the secretion of atrial natriuretic polypeptide (ANP) during salt loading (350 mEq/day) were studied in 12 healthy salt‐resistant normotensives under strictly controlled metabolic ward conditions.