Naokata Shimizu

CORRELATION OF PLASMA ACTH CONCENTRATION WITH ADRENOCORTICAL RESPONSE IN NORMAL HUMAN SUBJECTS, SURGICAL PATIENTS, AND PATIENTS WITH CUSHING'S DISEASE.

The role of ACTH in various clinical disorders has been difficult to ascertain because the available assay methods have lacked the sensitivity necessary for valid quantitation of the hormone in the plasma of normal subjects (1-4). Even the method of Lipscomb and Nelson (5), the most sensitive practical bioassay procedure now available, usually requires the injection of at least 0.05 mUof ACTHper rat, if responses are to be elicited that will be statistically significant without the use of a prohibitive number of animals. It is usually impractical to inject more than 5 ml of crude human plasma into a single rat. Therefore, in order to be accurately measurable by this procedure, the concentration of ACTH in the plasma must be at least 0.05 mUper 5 ml, or 1 mUper 100 ml. Numerous studies indicate that normal plasma levels of ACTHare well below this concentration. Byr the adrenal ascorbic acid depletion assay method, Sydnor, Sayers, Brown, and Tyler (1) were unable to detect ACTH in plasma of normal subjects, even after attempting to extract the hormone with oxvcellulose in preparation for the bioassay. These workers concluded that blood ACTH concentrations of normal human subjects were less than 0.5 mUper 100 ml. Using a similar procedure, Fujita (3) estimated the normal level of ACTHto be about 1 mUper L, i.e., 0.1 mUper 100 ml. Cooper and Nelson (6) were able to detect ACTH in the plasma of only 3 of 10 patients before surgery, by a method that they

Antithrombotic therapy with ticlopidine in chronic renal failure patients on maintenance hemodialysis -a multicenter collaborative double blind study-

Abstract The effect of a new inhibitor of platelet aggregation, ticlopidine, at a daily oral dose of 200mg, was investigated on prevention of thrombotic obstruction of the arterio-venous shunts or vascular grafts in 107 uremic patients under chronic hemodialysis: the patients were those who had suffered from frequent thrombotic episodes in their blood accesses. The study was conducted in a double blind fashion with an inactive placebo. Frequency of clot removal was significantly (p

Diurnal rhythm of plasma immunoreactive corticotropin-releasing factor in normal subjects

Plasma corticotropin-releasing factor (CRF), corticotropin (ACTH) and cortisol levels were simultaneously determined by radioimmunoassays at 0600 h, 1200 h, 1800 h and 2200 h in six normal subjects, in order to examine whether the diurnal rhythm in plasma CRF exists and how it correlates to the diurnal rhythm in plasma ACTH and cortisol concentration. The highest CRF level was observed at 0600 h (7.0 +/- 1.2 pg/ml) and significantly lower levels (p less than 0.01) at 1800 h (1.7 +/- 0.2 pg/ml) and 2200 h (1.9 +/- 0.4 pg/ml). A clear diurnal rhythm was demonstrated in plasma ACTH and cortisol levels, with the highest values at 0600 h (44.6 +/- 8.1 pg/ml and 15.9 +/- 2.0 micrograms/dl, respectively) and the lowest at 2200 h (12.3 +/- 2.8 pg/ml and 4.6 +/- 1.0 micrograms/ml, respectively). These results suggest that the diurnal rhythm in ACTH and cortisol is under the regulation, at least in part, of the diurnal rhythm in CRF secretion.

Effect of catecholamine on aldosterone release in isolated rat glomerulosa cell suspensions

Effect of adrenergic activity on the adrenal steroidogenesis and the modulation by catecholamines of aldosterone release were studied in isolated rat adrenal cell suspensions. Isoproterenol, norepinephrine and epinephrine, but not dopamine, caused statistically significant increase in aldosterone release. Both prazosin (alpha 1 antagonist) and yohimbine (alpha 2 antagonist) suppressed the norepinephrine-induced aldosterone release in a dose dependent manner, respectively. Both atenolol (beta 1 antagonist) and ICI 118-551 (beta 2 antagonist) also blocked (-)-isoproterenol-induced aldosterone release in a dose dependent manner, respectively. Neither (-)-isoproterenol nor (+/-)-norepinephrine at concentrations of 10(-6) M potentiated aldosterone release stimulated by angiotensin II or ACTH. These results suggest that catecholamines stimulate aldosteroidogenesis, but it appears unlikely that aldosterone release induced by ACTH or angiotensin-II is modulated by adrenergic stimulation.

Direct evidence for two distinct G proteins coupling with thrombin receptors in human neuroblastoma SH-EP cells

Thrombin receptor-G protein coupling was investigated in the human epithelial neuroblastoma cell line, SH-EP. In these cells, both alpha-thrombin and thrombin receptor peptides, SFLLRNP (one-letter amino-acid code), which are newly exposed following cleavage by alpha-thrombin, stimulated GTPase activity about 2-fold over basal activity. Pertussis toxin treatment only partially attenuated alpha-thrombin- and SFLLRNP-stimulated GTPase activity by 50%, whereas antibody raised against synthetic heptapeptide SFLLRNP blocked alpha-thrombin-stimulated phosphoinositide hydrolysis more than 80%. Immunoprecipitation studies using this antibody showed that both Gi2, a subtype of guanine nucleotide-binding regulatory proteins (G proteins) mediating inhibition of adenylyl cyclase, and Gq/G11, a G protein mediating stimulation of phospholipase C, were activated by alpha-thrombin. These data suggest that in these cells the thrombin receptor activates pertussis toxin-sensitive and pertussis toxin-insensitive G proteins simultaneously and directly couples to Gi2 and Gq/G11, which mediate different signaling pathways.

Effect of subcutaneous injection of a long-acting analogue of somatostatin (SMS 201–995) on plasma thyroid-stimulating hormone in normal human subjects

SMS 201-995 (SMS), a synthetic analogue of somatostatin (SRIF) has been shown to be effective in the treatment of the hypersecretion of hormones such as in acromegaly. However, little is known about the effects of SMS on the secretion of thyroid-stimulating hormone (TSH) in normal subjects. In this study, plasma TSH was determined with a highly sensitive immunoradiometric assay, in addition to the concentration of SMS in plasma and urine with a radioimmunoassay, following subcutaneous injection of 25, 50, 100 micrograms of SMS (4 subjects/dose) or a placebo (6 subjects) to normal male subjects, at 0900 h after an overnight fast. The plasma concentrations of SMS were dose-responsive and the peak levels were 1.61 +/- 0.09, 4.91 +/- 0.30 and 8.52 +/- 1.18 ng/ml, which were observed at 30, 15 and 45 min after the injection of 25, 50 and 100 micrograms of SMS, respectively. Mean plasma disappearance half-time of SMS was estimated to be 110 +/- 3 min. Plasma TSH was suppressed in a dose dependent manner and the suppression lasted for at least 8 hours. At 8 hours after the injection of 25, 50 and 100 micrograms of SMS, the plasma TSH levels were 43.8 +/- 19.4, 33.9 +/- 9.4 and 24.9 +/- 3.2%, respectively, of the basal values. The results suggest that SMS suppresses secretion of TSH from the normal thyrotrophs in man and thus also that attention should be paid to possible hypothyroidism during the long-term treatment of patients such as those with acromegaly with this potent analogue of SRIF.

Long-term event monitoring study of fluvastatin in Japanese patients with hypercholesterolemia: Efficacy and incidence of cardiac and other events in elderly patients (≥ 65 years old).

OBJECTIVE This long-term event monitoring (LEM) study was designed to evaluate the long-term lipid-lowering efficacy and safety of fluvastatin (Lochol®, Novartis A.G.) along with the incidence of cardiac and other events, and safety of fluvastatin in Japanese patients with hypercholesterolemia. METHODS Patients (n = 21,139) who started fluvastatin between April 1, 2000 and March 31, 2002, across 2563 centers in Japan were prospectively registered and followed up for 3 years (secondary prevention cohort) or 5 years (primary prevention cohort). RESULTS Of the patients registered, 19,084 were included in this analysis. Levels of low-density lipoprotein-cholesterol (LDL-C) and total cholesterol (TC) decreased significantly in the primary (-27.1% and -18.8%) and secondary (-25.3% and -18.4%) prevention cohorts. Reductions in LDL-C (-22.1 vs. -18.2%, p < 0.0001) and TC (-16.1 vs. -13.1%, p < 0.0001) levels were significantly greater among patients aged ≥ 65 than < 65 years old. Overall, 1.7% (146/8563) and 1.1% (93/8563) of patients aged ≥ 65 years old experienced confirmed cardiac and cerebral events, compared with 1.1% (112/10,517) and 0.3% (28/10,517) of patients aged < 65 years old (p = 0.0002 and < 0.0001, respectively). Incidence of cardiac and cerebral events was lowest in patients aged < 65 years old in the primary prevention cohort and highest among patients aged ≥ 65 years old in the secondary prevention cohort. Adverse events were reported in 7.9% (1501/19,084) of patients. CONCLUSION This large-scale, prospective, uncontrolled study confirmed the lipid-lowering efficacy and safety of long-term fluvastatin treatment for hypercholesterolemia in Japanese patients aged ≥ 65 years old. The higher incidence of cardiac and cerebral events in patients aged ≥ 65 years old in the secondary prevention cohort reflects a high-risk clinical profile with multiple classic risk factors warranting multifactorial interventions.

Androgen metabolism in cultured rat renal inner medullary collecting duct (IMCD) cells

Although the stimulations of renal hypertrophy and renal erythropoietin production have been well-known androgen effects in the kidney, recent investigative progresses are further providing good evidences for androgen-regulated gene productions of key enzymes or local hormone substrates important to renal cell metabolisms and tubular functions in mouse or rat proximal tubules, respectively. It has been also reported that testosterone restores vasopressin receptors in medullary collecting ducts of the ageing rat and improves a urinary concentrating ability. Therefore in the present study we examined a metabolic pathway of androgens in cultured rat renal IMCD cells, which finally determine a urinary composition and volume. IMCD cells cultured from kidneys of male Wistar rats weighing about 200 g were incubated with serum-free culture media containing 4 nM [3H] testosterone or [3H] androstenedione for 2-48 h. Radioactive compounds in incubation media were then separated by reverse-phase high-pressure liquid chromatography (HPLC) and identified mainly on the basis of comparison of retention times of standard materials on HPLC. The main metabolites identified in testosterone or androstenedione incubation experiment were 5 alpha-dihydrotestosterone or 5 alpha-androstanedione, respectively. 5 alpha-Reductase inhibitor, MK 906, effectively inhibited the formations of these Ring A reduced metabolites. These results may suggest that rat renal IMCD cells possess 5 alpha-reductase activity, thereby converting androgens into their biologically active forms in vivo.

Expression of insulin-like growth factor II by a gastric carcinoma associated with hypoglycaemia

A gastric cancer with liver metastases was associated with low morning levels of plasma glucose (24 mg/dl), insulin (<2.5 μU/ml) and growth hormone (0.23 ng/ml). Primary and metastatic tumour tissue stained positively with anti-insulin-like growth factor II(IGF-II) monoclonal antibody. Western immunoblot analysis revealed a high molecular weight IGF-II in the serum: 15 kDa (normal: 7.5 kDa). Postmortem reverse transcription polymerase chain reaction on mRNA from both sites revealed 471 base pairs size cDNA encoding prepro-IGF-II. These results suggest that the gastric carcinoma encoded, expressed, and secreted IGF-II, probably causing the extrapancreatic tumour hypoglycaemia.

Immunologic characterization of plasma glucagon components in a patient with malignant glucagonoma

Plasma immunoreactive glucagon (IRG) components were analyzed by gel filtration on either a Bio-Gel P-30 or a Sephadex G-150 column (1.0 X 68 cm) in a 47-year-old male with biopsy-proven malignant glucagonoma. Plasma samples were obtained before and after 20 courses of streptozotocin treatment as well as after administration of a somatostatin-derivative (SRIF-D, 0.38 mg, subcutaneous), regular insulin (0.2 U/kg, intravenous), and secretin (2 U/kg, intravenous). The fractions from the columns were assayed for IRG by simultaneous radioimmunoassay with C-terminal (Unger 30 K) and N-terminal (OAL 196) antibodies to glucagon. Four IRG components were observed. The largest had a molecular weight of approximately 150,000 daltons and cross-reacted much more strongly with the N-terminal antibody than with the C-terminal. The second IRG component appeared to be about 9000 daltons and cross-reacted more strongly with the N-terminal antibody. The third and major IRG component comprised 51.8% to 88.1% of the total IRG as measured with C-terminal antibody, corresponded in molecular weight to synthetic 3500 dalton glucagon, and reacted roughly equally with each of the two antibodies. The fourth IRG component cross-reacted only with N-terminal antibody and appeared to be smaller than 3500 daltons. The plasma IRG level decreased from 8829 pg/mL to 1421 pg/mL (averages of five consecutive determinations) after 20 courses of treatment with streptozotocin with significant clinical improvement. A marked (74%) but transient decrease in plasma IRG was observed after the SRIF-D injection, whereas secretion and insulin caused increases in plasma IRG level of 53% and 22%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)