Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth

The Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. The mission performed two landing operations to collect samples of surface and subsurface material, the latter exposed by an artificial impact. We present images of the second touchdown site, finding that ejecta from the impact crater was present at the sample location. Surface pebbles at both landing sites show morphological variations ranging from rugged to smooth, similar to Ryugu's boulders, and shapes from quasi-spherical to flattened. The samples were returned to Earth on 6 December 2020. We describe the morphology of >5 grams of returned pebbles and sand. Their diverse color, shape, and structure are consistent with the observed materials of Ryugu; we conclude that they are a representative sample of the asteroid.

The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes

The near-Earth carbonaceous asteroid 162173 Ryugu is thought to have been produced from a parent body that contained water ice and organic molecules. The Hayabusa2 spacecraft has obtained global multicolor images of Ryugu. Geomorphological features present include a circum-equatorial ridge, east-west dichotomy, high boulder abundances across the entire surface, and impact craters. Age estimates from the craters indicate a resurfacing age of [Formula: see text] years for the top 1-meter layer. Ryugu is among the darkest known bodies in the Solar System. The high abundance and spectral properties of boulders are consistent with moderately dehydrated materials, analogous to thermally metamorphosed meteorites found on Earth. The general uniformity in color across Ryugu's surface supports partial dehydration due to internal heating of the asteroid's parent body.

Detailed images of asteroid 25143 Itokawa from Hayabusa

Rendezvous of the Japanese spacecraft Hayabusa with the near-Earth asteroid 25143 Itokawa took place during the interval September through November 2005. The onboard camera imaged the solid surface of this tiny asteroid (535 meters by 294 meters by 209 meters) with a spatial resolution of 70 centimeters per pixel, revealing diverse surface morphologies. Unlike previously explored asteroids, the surface of Itokawa reveals both rough and smooth terrains. Craters generally show unclear morphologies. Numerous boulders on Itokawa's surface suggest a rubble-pile structure.

The rubble-pile asteroid Itokawa as observed by Hayabusa

During the interval from September through early December 2005, the Hayabusa spacecraft was in close proximity to near-Earth asteroid 25143 Itokawa, and a variety of data were taken on its shape, mass, and surface topography as well as its mineralogic and elemental abundances. The asteroid's orthogonal axes are 535, 294, and 209 meters, the mass is 3.51 x 10(10) kilograms, and the estimated bulk density is 1.9 +/- 0.13 grams per cubic centimeter. The correspondence between the smooth areas on the surface (Muses Sea and Sagamihara) and the gravitationally low regions suggests mass movement and an effective resurfacing process by impact jolting. Itokawa is considered to be a rubble-pile body because of its low bulk density, high porosity, boulder-rich appearance, and shape. The existence of very large boulders and pillars suggests an early collisional breakup of a preexisting parent asteroid followed by a re-agglomeration into a rubble-pile object.

Distribution of c-fos mRNA in the brain following intracerebroventricular injection of nitric oxide (NO)-releasing compounds: possible role of NO in central cardiovascular regulation

We injected nitric oxide (NO)-releasing compounds and NO synthase (NOS) inhibitors into the brains of conscious, freely moving rats and measured the effects on mean arterial blood pressure (MAP) and heart rate, as well as on the expression of c-fos mRNA, neuronal NOS (nNOS) mRNA and NADPH-diaphorase, an indicator of NOS activity. When administered i.c.v., the NO donor, NOC-18, caused a significant fall in MAP and heart rate, whereas the NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), induced a significant rise in MAP. The same dose of NOC-18 or L-NAME when administered i.v. did not affect MAP and heart rate. Centrally administered NOC-18 induced c-fos mRNA expression in several regions of the brain involved in the baroreceptor response, including the nucleus of the solitary tract, the area postrema and the rostral ventrolateral medulla, as well as areas involved in the integration of autonomic, neuroendocrine and behavioural responses, including the medial preoptic area, the organum vasculosum lamina terminalis, the bed nucleus of stria terminalis, the paraventricular nucleus (PVN), the supraoptic nucleus (SON), the central nucleus of amygdala (CeA) and the locus coeruleus. Most of the areas that expressed c-fos also contained nNOS mRNA and/or NADPH-d-positive neurones and fibres. i.c.v. injection of L-NAME induced c-fos mRNA expression in PVN, SON, locus coeruleus and NTS, suggesting a tonic inhibition of neuronal activity by NO or stimulation of neuronal activity by endogenous NO. i.v. injection of NOC-18 or L-NAME did not induce any significant c-fos mRNA expression in rat brain. These results demonstrate that NO acts directly in the brain to reduce the systemic blood pressure, and that the endogenous NO pathway may play a role in cardiovascular and autonomic regulation by modulating neuronal activities in discrete regions of the brain.

Adrenocortical carcinoma manifesting pure primary aldosteronism: a case report and analysis of steroidogenic enzymes

Adrenocortical carcinoma manifesting pure hyperaldosteronism is extremely rare. We report here a 61-year-old woman with biochemically proven primary aldosteronism due to right adrenocortical carcinoma. Computed tomographic scan showed 4.5x5.3 cm lobulated mass with tiny calcification, while there was no significant uptake of 131I-iodomethyl norcholesterol in the tumor. Immunohistochemical analysis demonstrated expression of steroidogenic enzymes in the tumor tissue: P-450scc, P-45c21, 3beta-hydroxysteroid dehydrogenase, P450(17alpha), and P-450(11beta). In addition, we could demonstrate mRNA expression of aldosterone synthase (P-450aldo:CYP11B2) in the tumor by specific ribonuclease protection assay. This is the first report of a case of primary aldosteronism due to adrenocortical carcinoma, in which expression of all sets of steroidogenic enzymes required for aldosterone synthesis was proven.

Changes in neoplastic cell features and sensitivity to mitotane during mitotane-induced remission in a patient with recurrent, metastatic adrenocortical carcinoma

A 58-year-old man had adrenocortical carcinoma in the right adrenal gland. The tumour secreted excessive cortisol and dehydroepiandrosterone-sulphate (DHEA-S), and had invaded the right hepatic lobe and vena cava. Eleven months after surgical tumour resection, the serum DHEA-S levels again increased. Local tumour recurrence and a metastasis was found in the lung. Eleven months after surgery chemotherapy with mitotane (o,p'-DDD) was initiated. Twelve weeks of mitotane reduced serum DHEA-S levels and caused these tumours to disappear. The patient was then treated with low-dose mitotane (1.5-2.0 g/day) for 2 years. Serum levels of mitotane remained at less than 10 microg/ml. Although such low serum levels of mitotane and delayed initiation of mitotane after surgery have been proposed to weaken the antineoplastic effect of mitotane, the patient had a remission for 2 years. However, there was then local re-recurrence with an increase in serum DHEA-S and death 4 months later. The histological features of neoplastic cells were quite different comparing tumour resected at surgery and tumour at autopsy. The latter had more frequent mitotic nuclei. This tumour was initially sensitive to mitotane, but later became insensitive.

Induction of heme oxygenase produces load-independent cardioprotective effects in hypertensive rats

Although heme oxygenase (HO) has been suggested to be involved in the regulation of cardiovascular function through production of carbon monoxide (CO), the pathophysiological significance of HO in hypertensive organ damage remains unknown. We examined the effects of inducing HO-1 mRNA by stannous chloride (SnCl2) on cardiac hypertrophy in stroke-prone spontaneously hypertensive rats (SHR-SP/Izm). Chronic administration of SnCl2 resulted in a significant decrease in left ventricular (LV) weight/body weight ratio and LV brain natriuretic peptide (BNP) mRNA levels as a marker of cardiac hypertrophy and a significant increase in LV HO-1 mRNA levels and LV cGMP contents in SHR-SP/Izm, while there was no significant change in systemic blood pressure. These results provide the first evidence that induction of HO in the heart attenuates cardiac hypertrophy in load-independent mechanism in genetically hypertensive rats.

Vasculo-protective effects of insulin sensitizing agent pioglitazone in neointimal thickening and hypertensive vascular hypertrophy

A novel insulin sensitizing agent, thiazolidine, has been demonstrated to inhibit the growth of cultured vascular smooth muscle cells (VSMC) in vitro. This study was undertaken to examine the in vivo effects of the thiazolidine compound pioglitazone (PIO) on carotid neointimal thickening, after endothelial injury in Wistar rats and vascular hypertrophy in stroke-prone spontaneously hypertensive rats (SHR-SP/Izm). PIO treatment (3 mg/kg/day for 1 week prior to endothelial injury and 2 weeks postendothelial injury) remarkably decreased neointimal cross-sectional areas in treated animals (63.8 +/- 4.9 x 10(3) microm2) versus controls (196 +/- 7.6 x 10(3) microm2, P < 0.05). Bromodeoxyuridine uptake in the neointima, a marker of DNA synthesis, was also decreased after treatment compared with controls. In SHR-SP/Izm but not in Wistar rats, PIO treatment decreased blood pressure and plasma insulin levels. PIO treatment in SHR-SP/Izm (3 mg/kg/day from 4 weeks of age for 7 weeks) significantly decreased the medial wall thickness of the mesenteric artery (10.4 +/- 1.2 x 10(3) microm2 versus control, 21.2 +/- 2.4 x 10(3) microm2, P < 0.05). In addition, PIO treatment significantly decreased the expression of EIIIA fibronectin both in the carotid neointima of Wistar rats and the media of the mesenteric artery in SHR-SP/Izm compared with their respective controls (P < 0.05). These results suggest that PIO has vasculo-protective effects in both acute and chronic vascular injury in vivo through inhibition of VSMC proliferation.

Angiotensin II type 1 receptor expression in two cases of juxtaglomerular cell tumor: correlation to negative feedback of renin secretion by angiotensin II

The angiotensin II (Ang II) type 1 (AT1) receptor is highly expressed on juxtaglomerular (G) cells and is assumed to be involved in the negative short loop feedback regulation of renin secretion and in the suppression of Ang II-mediated JG cell proliferation and/or growth. However, as JG cell tumor is rare, expression and pathophysiological significance of AT1 receptor expression in JG cell tumor remain unknown. In the present study, we investigated renin responses to various treatments, including the angiotensin converting enzyme inhibitor captopril, and correlated the results with AT1 and Ang II type 2 (AT2) receptor mRNA expression levels in two cases of JG cell tumor. Whereas plasma renin activity (PRA) did not show any significant change in Case 1, it was increased by 72% in Case 2 in response to captopril challenge. In concordance with these results, AT1 receptor mRNA was not detected in tumor tissue of Case 1 but was clearly demonstrated in the tumor of Case 2. AT2 receptor mRNA expression was not detected in either of the cases. In contrast to captopril challenge, PRA was suppressed by 30% in Case 1 and 42% in Case 2 in response to saline infusion, and was increased by 230% in Case 1 and 59% in Case 2 in response to furosemide-upright posture for 2 h. These results suggest that the short loop feedback inhibition of renin secretion by Ang II in JG cell tumor is closely related to AT1 receptor expression levels in the tumor tissue. In addition, the result suggested that despite its autonomy, renin secretion from JG cell tumor is still under physiological regulatory control.

Ipriflavone down-regulates endothelin receptor levels during differentiation of rat calvarial osteoblast-like cells

Ipriflavone (7-isopropoxy-3-phenyl-4H-1-benzopyran-4-one) is a synthetic flavonoid that has been shown to stimulate the activity of osteoblasts. We show here that ipriflavone also promotes the deposition of calcium and the formation of mineralized nodules by newborn rat calvarial osteoblast-like (ROB) cells as well as the activity of alkaline phosphatase. We reported previously that endothelin-1 inhibits the differentiation of ROB cells [Y. Hiruma et al. (1998) J. Cardiovasc. Pharmacol. 31, S521-S523]. Therefore, we examined the effects of ipriflavone on the expression of endothelin receptors in ROB cells by polymerase chain reaction-Southern blot analysis and in binding assays with 125I-labeled endothelin-1. Ipriflavone reduced levels of endothelin ETA receptors (to 48% of the control level) in ROB cells around day 7 in our standard cultures, while it had no apparent effect on the expression of the mRNA for the endothelin ETA receptor. By contrast, treatment with 10(-7) M endothelin-1 on days 6 through 9 alone suppressed mineralization by ROB cells. Ipriflavone also reduced the ability of endothelin-1 to inhibit mineralization by ROB cells. These results suggest that the acceleration of osteoblastic differentiation by ipriflavone might be due, at least in part, to a time-specific down-regulation of endothelin receptors.

Growth hormone directly inhibits leptin gene expression in visceral fat tissue in fatty Zucker rats

Growth hormone (GH) is known to interact with adipose tissue and to induce lipolysis. Adipocytes produce leptin which regulates appetite and energy expenditure. In order to elucidate the role of GH in leptin production, we studied the effect of GH on leptin gene expression and body fat in fatty Zucker rats, a model of obesity with resistance to both leptin and insulin. Recombinant human GH administered subcutaneously at 0.5 mg/kg per day (low dose) as well as at 1.65 mg/kg per day (high dose) reduced leptin mRNA levels in epididymal fat tissue but not in subcutaneous fat tissue after 7 days. GH administration only at the high dose reduced percentage body fat. Insulin-like growth factor-I infusion (200 microg/kg per day) did not change percentage body fat or leptin mRNA levels in epididymal fat. These observations suggest that GH directly interacts with adipose tissue and reduces leptin gene expression in visceral fat tissue.

Decreased serum levels of acid-labile subunit in patients with anorexia nervosa

One of the observations in malnutrition is that serum insulin-like growth factor (IGF)-I levels are decreased, and this decrease is associated with an altered profile of IGF binding proteins (IGFBPs). In human circulation, IGFs are mostly present as an approximately 150-kDa ternary protein complex consisting of IGFs, IGFBP-3, and acid-labile subunit (ALS). In the present study, to clarify the effect of nutrition on serum ALS levels, we investigated 33 patients with anorexia nervosa. Serum levels of ALS were measured by RIA. Furthermore, we measured serum IGF-I, IGF-II, IGFBP-2, and IGFBP-3 levels in the patients. From these data, we investigated which was the best predictor of body mass index (BMI) as a nutritional status marker. In the patients with anorexia nervosa, the serum ALS levels ranged from 0.7-16.9, with a mean of 10.6 +/- 0.7 mg/L, and the levels were significantly lower than those of normal subjects (13.8 +/- 0.8 mg/L, P < 0.05). Serum ALS levels positively correlated with BMI (r = 0.41, P < 0.05), and the levels increased during treatment. The serum IGFBP-2 levels in the patients were increased (871 +/- 91 microg/L), and the levels inversely correlated with BMI (r = -0.52, P < 0.01). The serum IGF-I and IGFBP-3 levels were low (152 +/- 14 microg/L and 2.56 +/- 0.12 mg/L, respectively), and the levels positively correlated with BMI (r = 0.46, P < 0.01; and r = 0.39, P < 0.05, respectively). The serum IGFBP-2, IGF-I, and IGFBP-3 levels returned toward normal ranges as BMI in the patients improved during treatment. Serum IGF-II levels did not correlate with BMI (r = 0.24, P = 0.17). Stepwise regression analysis revealed that serum IGFBP-2 was the best marker of BMI among these variables. The present study suggested that ALS was regulated by nutritional status, the same as IGF-I, IGFBP-2 and IGFBP-3; but the serum IGFBP-2 was the best predictor of BMI as nutritional status marker among the parameters in patients with anorexia nervosa.

Urocortin mRNA is expressed in the enteric nervous system of the rat

The expression of the urocortin gene in the gastrointestinal tract was investigated using reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization histochemistry. PCR demonstrated the presence of urocortin mRNA in the rat brain, duodenum, small intestine, and colon. By in situ hybridization, urocortin-containing cells were exclusively localized to the submucosal plexus and myenteric plexus in the duodenum, small intestine and colon. These results suggest that urocortin may play an important role in the regulation of gastrointestinal motor function throughout the enteric nervous system.

[Angiotensin II receptor subtype in human adrenal glands]

Although adrenal gland is one of the major target organs of angiotensin II (Ang II), the pathophysiological significance of the its receptor subtype has not been elucidated. We demonstrated by reverse transcription-polymerase chain reaction with Southern blot analysis mRNA expression of both AT1 and AT2 in human adrenal tissues of normal adrenocortical tissues, aldosterone-producing adenoma, Cushing's syndrome, and pheochromocytoma. Ang II-induced aldosterone secretion in vitro was suppressed only by 50% in the presence of selective AT1 antagonist CV-11974, while AT2 agonist CGP-42112 increased aldosterone secretion by 55% over the control. Ang II or CGP-42112 did not affect cortisol secretion. In addition, Ang II could stimulate aldosterone secretion in AT1a knockout mice both in the presence and absence of CV-11974. These results suggest that non-AT1 receptor subtype(s) including AT2, as well as AT1, is involved in the stimulation of aldosterone secretion from human adrenals.

[Renin-angiotensin-aldosterone system in the reproductive system]

Besides the circulating renin-angiotensin-aldosterone (R-A-A) system, the tissue R-A-A system has been elucidated to play important roles as autocrines and/or paracrines. The components of R-A-A system are expressed in the ovary, uterus and placenta, indicating the existence of the tissue R-A-A system in these organs. The data indicating the involvement of R-A-A system of these tissues into reproduction have been accumulated. AT2 receptors might modulate the initiation and progression of follicle atresia involving granulosa cell apoptosis. AT2 receptors are expressed abundantly in the uterus and decreased during pregnancy. The placental renin are shown to be secreted into the maternal circulation and elevate blood pressure. It is expected to elucidate the significance of the R-A-A system in the reproductive system.

An additional exon of stress-inducible heat shock protein 70 gene (HSP70-1)

The HSP70-1 gene, reportedly a single exon, encodes a major stress-inducible 72-kDa heat shock protein (HSP70). We recently demonstrated that patients with major depression had a 162-base pair (bp)-deletion in the 5'-flanking sequence of HSP70-1 mRNA in their peripheral blood mononuclear cells. Present study has been conducted to clarify how this short mRNA is generated, and demonstrated that a novel 385 bp sequence is located 1.1 kb upstream from the HSP70-1 gene of normal subjects. Except for the 162 bp deletion, it is compatible with part of the 5'-flanking sequence of the HSP70-1 gene, and contains another exon of 358 bp (exon 1) that may be connected to the 3'-terminus (exon 3) of the conventional HSP70-1 gene. Alternative transcription of exons 1 and 3 may cause the short mRNA. It is concluded that HSP70-1 gene is constituted of three exons and may cause alternative splicing.

Corticotropin-releasing factor receptor type 1 mediates emotional stress-induced inhibition of food intake and behavioral changes in rats

We investigated whether corticotropin-releasing factor (CRF) receptor type 1 (CRFR1) is involved in emotional stress-induced inhibition of food intake and behavioral changes in rats. The inhibition of food intake and increase in locomotor activity induced by emotional stress using a communication box were reversed by both intracerebroventricular injection of alpha-helical CRF (9-41), a non-selective CRF receptor antagonist, and intraperitoneal injection of a selective non-peptidic CRFR1 antagonist. These results suggest that CRFR1 mediates at least in part the emotional stress-induced inhibition of feeding behavior and increase in locomotor activity.

Distinct distribution and time-course changes in neuronal nitric oxide synthase and inducible NOS in the paraventricular nucleus following lipopolysaccharide injection

Nitric oxide (NO) is known to be involved in the modulation of neuroendocrine function. To clarify the role of different isoforms of NO synthase (NOS) in the neuroendocrine response to immune challenge, the expressions of neuronal NOS (nNOS) and inducible NOS (iNOS) genes in the hypothalamus following lipopolysaccharide (LPS) injection were examined using in situ hybridization. NOS activity was also determined by NADPH-diaphorase (NADPH-d) histochemistry. LPS (25 mg/kg) or sterile saline was injected intraperitoneally to male Wistar rats and the rats sacrificed 30 min, or 1, 2, 3, 5, 12 or 24 h after injection. nNOS mRNA expression in the paraventricular nucleus (PVN) was significantly increased 2 h after LPS injection. iNOS mRNA, which was not detected until 2 h after LPS injection, was significantly increased in the PVN 3 h after LPS injection. Both RNA expressions had returned to basal levels by 12 h after LPS injection. The number of NADPH-d positive cells was significantly increased 5 h after LPS injection. iNOS expression was more robust in parvocellular PVN, while nNOS was distributed mainly in the magnocellular PVN. Double in situ hybridization histochemistry revealed that some of the iNOS- (48.4%) or nNOS-positive cells (34. 3%) in the parvocellular PVN expressed CRF mRNA. The results demonstrate that LPS-induced sepsis causes significant increases in nNOS and iNOS gene expression with different time-courses and distributions, and that iNOS mRNA was more frequently co-localized with CRF-producing parvocellular neurons in the PVN. Thus, NO produced by iNOS and nNOS may play an important role in the neuroendocrine response to an immune challenge. Distinct differences in the distribution and time-course changes of iNOS and nNOS suggest different roles for the hypothalamic-pituitary-adrenal axis and/or neurohypophyseal system.

Interaction between leptin and growth hormone (GH)/IGF-I axis

In order to identify the mutual interaction between GH and leptin, we studied the effect of GH on fatty Zucker rats. GH administration at a high dose (5.0 IU/kg) reduced % body fat after 7 days. The leptin mRNA level in subcutaneous fat tissue was not changed but that in epididymal fat tissue was decreased by an even lower dose of GH (1.5 IU/kg). IGF-I treatment (200 microg/kg/day) did not change the % body fat or leptin mRNA level. These observations suggest that GH directly interacts with visceral fat and reduces fat mass and leptin expression. We also measured serum leptin levels in patients. The levels in patients with acromegaly were significantly lower than those in normal subjects with the same amount of body fat, but serum IGF-I and urinary C peptide excretion rates were higher in the acromegalic. These observations also suggests that GH directly interacts with adipose tissue and reduces leptin expression. Next we investigated the direct action of leptin on GH release from the pituitary. Leptin pretreatment of pituitary cells in culture or rats in a fasted or fed condition did not change GRH induced GH secretion. As indicated also by other recent studies, leptin may increase GRH or decrease somatostatin secretion by the hypothalamus. Thus GH interacts with fat tissues and leptin may be a good marker of the interaction.

Surgical stress increases renal glutathione content via increased glucocorticoid, and resistance to subsequent oxidative injury in the rat: significant link between endocrine response and cell defense system under the stress

Systemic and nonspecific stress response effects on the cellular defense mechanism were studied in the male rat kidney. Two days after laparotomy-induced surgical stress, rats showed increased serum corticosterone and renal cortical reduced glutathione (GSH). Rats were then injected s.c. with mercuric chloride (HgCl2) to oxidatively injure renal tubuli. Increased serum creatinine levels indicated that laparotomy pretreatment lessened renal damage. To study the effects of the activated pituitary-adrenal axis on renal cortical GSH content and vulnerability to subsequent oxidative injury, rats were injected s.c. with ACTH on two consecutive days. ACTH administration increased both corticosterone and aldosterone. These rats showed increased, dose-dependent renal cortical GSH content, i.e., controls (n=7): 1.25 +/- 0.23 micromol/g tissue, daily dose of 10 microg/100 gBW (n=7): 1.53 +/- 0.24 micromol/g tissue, and daily dose of 40 microg/100 gBW (n=7): 2.31 +/- 0.23 micromol/g tissue. Rats receiving daily doses of 40 microg of ACTH/100 gBW acquired resistance to oxidative injury, indicated by serum creatinine levels: controls (n=6), 22 +/- 4 micromol/L; HgCl2 (n=6), 145 +/- 88 micromol/L; ACTH and HgCl2 (n=6), 37 +/- 11 micromol/L. Morphological evidence indicated that ACTH pretreatment in HgCl2-injected rats prevented renal tissue from inflammatory cell infiltration but not from tubular degeneration. Cellular GSH content of LLC-PK1 cells, porcine renal-tubule-derived culture cells, increased significantly in incubation with dexamethasone or aldosterone, suggesting that adrenal steroids directly stimulate renal cell GSH. We demonstrated that stress or ACTH administration activates the defense mechanism in the kidney via increased GSH. This stress-activatable defense system may therefore indicate a connection between endocrine stress response and the cellular defense mechanism.

Osteo-anabolic effects of human growth hormone with 22K- and 20K Daltons on human osteoblast-like cells

Human growth hormone with 22,000 Dal (22K-hGH) stimulates proliferation and differentiation of osteoblasts as well as production of interleukin-6 in vitro and bone formation and remodeling in vivo. To investigate whether hGH isoform with 20Kd (20K-hGH), which accounts for 10% of circulating hGH, elicits similar metabolic effects on skeletal tissues, we studied the biological effects of 20K-hGH in cultured human osteoblast-like cells (HOB). HOB were obtained from trabecular bone explants and cultured in alpha-MEM supplemented with 10% FCS. In subconfluent cultures, 22K- and 20K-hGH stimulated [3H]thymidine incorporation by 62 +/- 27% and 63 +/- 23%, respectively (mean +/- SD, n=8, P>0.1). In confluent cultures, 22K- and 20K-hGH increased alkaline phosphatase activity by 38 +/- 23% and 41 +/- 23% (P>0.1), respectively, and increased the osteocalcin concentration in the presence of 10(-9) M 1,25-(OH)2D3 by 50% and 47% (P>0.1), respectively. Furthermore, both hGHs doubled the interleukin-6 (IL-6) concentration in the conditioned medium. RT-PCR analysis revealed that 22K- and 20K- hGH increased IL-6 gene expression 2.2 +/- 0.6 and 2.4 +/- 0.7 -fold, respectively. In summary, we have demonstrated that 20K-hGH elicits equipotent anabolic effects on HOB and stimulates to the same extent the production of IL-6, a cytokine which initiates osteoclastogenesis. These in vitro findings suggest that 22K- and 20K-hGH may equipotently stimulate bone remodeling and elicit anabolic effects on skeletal tissue when administered in vivo.

Amelioration of acromegaly after pituitary infarction due to gastrointestinal hemorrhage from gastric ulcer

We report a rare case of acromegaly in which pituitary infarction possibly developed in a GH-producing pituitary adenoma following gastrointestinal bleeding from peptic ulcer. In this case, pituitary infarction resulted in spontaneous remission of acromegaly associated with diabetes mellitus. In addition, detailed histological investigation revealed that clinically silent pituitary apoplexy was mainly an acute ischemic event which occurred recently in a GH-producing adenoma. This event led to massive coagulation necrosis of the tumor and endocrinological improvement.

Effects of two calcium channel blockers on messenger RNA expression of endothelin-1 and nitric oxide synthase in cardiovascular tissue of hypertensive rats

OBJECTIVE

The aim of this study was to investigate the effects of calcium channel blockers on messenger RNA expression of endothelin-1 and endothelial-type nitric oxide synthase in the cardiovascular tissue of stroke-prone spontaneously hypertensive rats (SHRSP).

MATERIALS AND METHODS

The calcium channel blocker nilvadipine (1.0 or 3.2 mg/kg per day) was subcutaneously administered to two groups of SHRSP, from 4 or 8 weeks of age, for 8 weeks and 4 weeks, respectively. For comparison, nifedipine (3.2 mg/kg per day) was similarly administered to SHRSP from 4 weeks of age for 8 weeks. Kidney, heart, aorta and brain tissue samples were obtained when the rats were 12 weeks old. Messenger RNA expression of endothelin-1 and endothelial-type nitric oxide synthase was determined by reverse transcription-polymerase chain reaction followed by Southern blotting and a ribonuclease protection assay, respectively. Results were compared with those in untreated SHRSP and Wistar-Kyoto rats at 12 weeks of age.

RESULTS

Both nilvadipine and nifedipine significantly decreased blood pressure in SHRSP. Although there were no changes in the weights of the kidney and brain, there was a significant decrease in the weight of the left ventricle of the groups treated with nilvadipine (1.0 mg/kg per day: mean +/- SEM 0.282 +/- 0.003 g; 3.2 mg/kg per day: 0.269 +/- 0.005 g) and nifedipine (1 mg/kg/day: 0.281 +/- 0.012 g) for 8 weeks compared with untreated SHRSP (0.301 +/- 0.004 g). Endothelin-1 messenger RNA expression, which was significantly increased by about twofold in the kidney, heart and brain of SHRSP compared with Wistar-Kyoto rats, was normalized by both calcium blockers. Endothelin-1 messenger RNA expression, which was decreased in the aorta of SHRSP, was further decreased by both calcium blockers. While there was no significant difference in endothelial-type nitric oxide synthase messenger RNA expression in the kidney, heart and aorta between the untreated SHRSP and Wistar-Kyoto rats, expression in the aorta was significantly increased in the group treated with these calcium blockers for 8 weeks from 4 weeks of age.

CONCLUSIONS

These results suggest that, in addition to their potent antihypertensive effects, calcium channel blockers may exhibit cardiovasculoprotective and renoprotective effects by modifying mRNA expression of endothelin-1 and endothelial-type nitric oxide synthase in tissue.

Changes in serum insulin-like growth factor binding protein-2, -3, and -6 levels in patients with chronic renal failure following renal transplantation

The pathophysiological roles of insulin-like growth factor binding protein (IGFBP)-6 have not been elucidated. Recently, we measured serum IGFBP-6 by Western immunoblot (WIB) and have found that serum IGFBP-6 levels increased in patients with chronic renal failure (CRF). In the present study, serum IGFBP-6 levels were measured in 10 patients with CRF before and 1, 7 and 14 days after renal transplantation to investigate further clinical significance and regulation of serum IGFBP-6. IGFBP-2 and -3 levels, usually elevated in patients with CRF, were also measured after renal transplantation. Serum IGFBP-2 and -6 levels from patients with CRF by Western immunoblot increased to 230+/-90% (mean +/- SD), and 400+/-110% of the reference serum, respectively, and these levels did not change after hemodialysis. Serum IGFBP-6 levels decreased to 47+/-20% of the basal level 1 day after renal transplantation, and the IGFBP-6 levels in two patients whose renal function worsened again due to rejection increased to more than 60% of the basal levels on the 14th day. In contrast to IGFBP-6, serum IGFBP-2 levels did not decrease during the 14 days after renal transplantation in all patients. Serum IGFBP-3 levels were significantly higher in CRF than normal sera (5.5+/-1.2 vs 3.7+/-0.5 microg/ml, P < 0.01), and the levels decreased to the normal range (2.7+/-1.0 microg/ml) within 1 day after the transplantation, whereas the levels increased again in one of two patients with poorly-functioning graft. In addition, we demonstrated IGFBP-6 in urine from normal adults. These results indicate that IGFBP-6 might be excreted by the kidneys and serum IGFBP-3 and -6 levels might be related with renal function, and that the regulation of serum IGFBP-2 levels differs from those of IGFBP-3 and -6.

Amiodarone-induced thyrotoxicosis associated with thyrotropin receptor antibody

Since amiodarone was first marketed in 1992 in Japan, the incidence of amiodarone-induced thyrotoxicosis (AIT) has been increasing. Among 12 thyrotoxic patients, a patient with arrhythmogenic right ventricular dysplasia, who had been taking amiodarone for 4 years, developed thyrotoxicosis with subacute onset, accompanied by transiently positive thyrotropin (TSH) receptor antibody (TRAb), or thyrotropin-binding inhibiting immunoglobulin (TBII). The immunoglobulin G (IgG) obtained from the TRAb-positive serum of the patient elicited no thyroid hormone-releasing activity in cultured human thyroid follicles, whereas all IgGs obtained from untreated Graves' disease elicited positive results. These in vitro findings and clinical course suggest that TRAb/TBII without thyroid-stimulating activity may develop in patients with amiodarone-induced destructive thyroiditis, as reported in patients with destructive thyroiditis, such as subacute and silent thyroiditis.

Hypercalcemia in an euthyroid patient with secondary hypoadrenalism and diabetes insipidus due to hypothalamic tumor

A 20-year-old Japanese man with a hypothalamic tumor (most likely germ-cell tumor) which caused secondary hypoadrenalism, hypogonadism and diabetes insipidus developed hypercalcemia and acute renal failure. The serum levels of intact PTH (iPTH), PTH-related protein (PTH-rP), 1,25-dihydroxy vitamin D (1,25- (OH)2 D), ACTH, cortisol, gonadotropins and testosterone were decreased, but his serum levels of triiodothyronine (T3) and thyroxine (T4) were within the normal range at admission, with depressed TSH and slightly increased thyroglobulin. The hypercalcemia was refractory to extensive hydration and calcitonin, but was ameliorated by pamidronate. After irradiation of the hypothalamic tumor, panhypopituitarism gradually developed. The patient has been normocalcemic for the last 2 years and is doing well under replacement therapy with glucocorticoid, L-thyroxine, methyltestosterone and 1-desamino D arginine vasopressin (dDAVP). As to the mechanism of euthyroidism at admission, transient destructive thyroiditis associated with hypopituitarism or delayed development of hypothyroidism following the hypoadrenalism was suggested. This is the first reported case of hypercalcemia in secondary hypoadrenalism due to hypothalamic tumor. Hypercalcemia was most likely induced by increased bone resorption, which was probably elicited by the combined effects of deficient glucocorticoid and sufficient thyroid hormones in addition to hypovolemia and reduced renal calcium excretion. Furthermore, severe dehydration due to diabetes insipidus and disturbance of thirst sensation caused by the hypothalamic tumor aggravated the hypercalcemia, leading to acute renal failure.

Deferential roles of angiotensin receptor subtypes in adrenocortical function in mice

The functional significance of angiotensin II (Ang II) receptor subtypes in adrenals remains unknown. Ang II receptor type 1a (AT1a) expression was localized by in situ hybridization to the zona glomerulosa and zona fasciculata, while AT1b was localized to the zona glomerulosa. Plasma aldosterone and corticosterone levels were measured after injection with Ang II or the type 2 receptor (AT2) agonist CGP-42112 in wild-type and AT1a deficient mice. Aldosterone and corticosterone levels were lower in AT1a deficient mice. Ang II increased plasma aldosterone levels in AT1a deficient mice, but to a lesser extent in mice pretreated with nonselective AT1a/AT1b antagonist, CV-11974. CGP-42112 did not affect aldosterone levels. Ang II increased corticosterone levels in wild-type mice but not in AT1a deficient mice. Results suggest Ang II stimulates aldosterone secretion via AT1a and AT1b in the zona glomerulosa and corticosterone secretion via AT1a in the zona fasciculata, and provide first evidence for differential roles of AT1a and AT1b in the adrenals.

The relatively high frequency of p53 gene mutations in multiple and malignant phaeochromocytomas

To explore the clinical significance of p53 in the pathogenesis of adrenal neoplasms, we investigated the incidence of p53 gene mutations in functioning human adrenal tumours using the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique to screen p53 exons 4 to 9. We examined 29 adrenocortical adenomas (primary aldosteronism, n=17; Cushing's syndrome, n=12, all benign), and 33 phaeochromocytomas (benign solitary, n=18; benign multiple, n=5; malignant, n=10) in Japanese and Chinese patients. PCR-SSCP did not show any abnormal band-shifts in any of the adrenocortical adenoma and benign solitary phaeochromocytoma tissues. In contrast, six phaeochromocytoma tissues (two cases benign multiple, four cases malignant) showed PCR-SSCP band-shifts. Subsequent DNA sequencing analysis of the shifted bands revealed six cases with nine mutations or intronic sequence alterations: three cases contained sequence alterations within intronic regions, three cases with silent mutation (sequence alteration in codon without amino acid alteration), and three cases contained missense mutations (one case each in exons 5, 6 and 9). Immunohistochemical staining demonstrated that two of three cases with missense mutations and one case with an intronic sequence alteration over-expressed p53 protein in tumour cell nuclei. We observed no association between p53 gene mutation and p21/WAF1/Cip-1 expression. The relatively high incidence of p53 gene mutations or intronic sequence alteration in multiple and malignant phaeochromocytomas, but not in benign solitary cases, suggests that p53 mutation could play some role in the pathogenesis of multiple and/or malignant phaeochromocytomas.

Angiotensin II stimulates both aldosterone secretion and DNA synthesis via type 1 but not type 2 receptors in bovine adrenocortical cells

Angiotensin II (Ang II) type 2 receptor (AT2) has been shown to counteract the type 1 receptor (AT1)-mediated biological actions of Ang II in the cardiovascular system. The biological significance of AT2 receptor in the adrenals however remains unknown. In the present study, we investigated the roles of AT1 and AT2 receptor subtypes in the regulation of aldosterone secretion and DNA synthesis in bovine adrenocortical zona glomerulosa cells in vitro. Ang II (1 mumol/l)-stimulated aldosterone secretion was completely suppressed by AT1 antagonist CV-11974 but not affected by AT2 receptor antagonist PD-123319. Effects on DNA synthesis were investigated by determining the incorporation of BrdU into the nuclei of the cultured zona glomerulosa cells. Ang II (1 mumol/l)-stimulated DNA synthesis of the cells was also completely suppressed by CV-11974 but not by PD-123319. These results suggest that AT1 receptor but not AT2 receptor is the predominant receptor subtype which mediates the Ang II-stimulated aldosterone secretion and cell growth in bovine adrenocortical cells.

Cardiac malignant pheochromocytoma with bone metastases

A patient with malignant cardiac pheochromocytoma with bone metastases is described. The primary tumor was located between the pulmonary trunk and the left atrium, while metastatic lesions were found in the iliac bones. Treatments with antihypertensive agents, alpha-methylparatyrosine, and combination chemotherapy with cyclophosphamide, vincristine, and dacarbazine partially improved the patient's symptoms, catecholamine levels, and the metastatic lesion of the iliac bones. However, the primary tumor in the heart progressively increased in size and the patient died of disseminated intravascular coagulation and other various complications about 4 years after the diagnosis of the disease.

Effect of growth hormone (GH) on serum concentrations of leptin: study in patients with acromegaly and GH deficiency

As leptin, an ob gene product, plays a pivotal role in the regulation of adiposity and energy homeostasis, the level of its expression is likely to fluctuate under various physiological, nutritional, and disease conditions. Reports regarding the effect of GH on serum leptin levels are inconsistent. We have measured serum leptin levels and correlated them with several variables in patients with acromegaly, patients with adult GH deficiency (GHD), and normal controls. In 116 normal subjects, the mean serum concentration of leptin was 5.0+/-2.8 (mean +/- SD) ng/mL in men (n = 42) and 10.7+/-7.3 ng/mL in women (n = 73), respectively. As reported previously, the leptin levels in women were significantly (P < 0.001) higher than in men, and there was a strong positive correlation between log-transformed serum leptin levels and percent body fat in simple regression analysis (in men: r = 0.606; P < 0.0001; in women: r = 0.707; P < 0.0001). In 36 acromegalic patients, the percent body fat mass was significantly lower than that in normal subjects, and the mean serum leptin level was 2.2+/-1.8 ng/mL in men (n = 18) and 3.6+/-2.5 ng/mL in women (n = 18). Analysis of covariance revealed that serum leptin levels in acromegalics were significantly lower than those in normal subjects after correcting percent body fat (P = 0.016 for men and P < 0001 for women). In male patients with GHD (n = 20), the mean percent body fat was significantly (P < 0.05) higher than that in age-matched controls, whereas the value in female GHD patients (n = 15) did not differ from that in age-matched controls. Serum leptin levels in GHD patients were 5.1+/-2.5 ng/mL in men and 11.5+/-8.1 ng/mL in women, which were not different from those in normal subjects adjusted for percent body fat mass. In multiple regression analysis models with log-transformed leptin as the dependent variable, gender, percent body fat (or body fat mass), and serum insulin-like growth factor I levels entered the equations at a statistically significant level. These data suggest that excess GH/insulin-like growth factor I reduces serum leptin levels by reducing body fat mass and/or by unknown mechanisms.

The genomic organization of the human corticotropin-releasing factor type-1 receptor

We determined the genomic organization of human CRF type-1 receptor (hCRF-R1). The gene coding for hCRF-R1 consists of at least 14 exons and spans over 20 kilobases. hCRF-R1's three reported isoforms originate from the same gene by alternative splicing. The first hCRF-R1, which binds to CRF with the highest affinity and transduces the most sensitive cAMP accumulation in response to CRF, is encoded in a total of 13 exons, the only one excluded being exon 6. The second isoform contains an additional 29-amino acid sequence which corresponds to exon 6. Unlike the first isoform, the third lacks a 40-amino acid sequence, corresponding to exon 3. Exon-intron boundaries are the same as that of the consensus sequence. Locations of introns in the coding sequence are similar to human CRF-R1, rat CRF-R1, human CRF-R2alpha and others belonging to the human glucagon receptor family.

The importance of body weight history in the occurrence and recovery of osteoporosis in patients with anorexia nervosa: evaluation by dual X-ray absorptiometry and bone metabolic markers

In order to investigate the risk factors, pathogenesis and natural course of the osteoporosis frequently seen in anorexia nervosa, we measured the bone mineral density (BMD) of the lumbar spine using dual X-ray absorptiometry in 51 Japanese female patients with anorexia nervosa, and followed the change in BMD of 29 patients for 11 to 46 months. We also evaluated the serum osteocalcin and the urinary CrossLaps, degradation products of collagen I, in 103 samples obtained from 51 patients. There was a significant correlation between the spinal BMD and the duration of emaciation below a body mass index (BMI) of 15kg/m2 (r= -0.652, P<0.0001) and 16kg/m2 (r= -0.647, P<0.0001). The increase in BMD per year in the 29 patients significantly correlated with the BMI at the time of entry of each follow-up period (r= 0. 712, P<0.0001). The critical BMI for a positive increase in BMD was 16.4+/-0.3 kg/m2 (mean+/-S.E.M.). The serum osteocalcin declined, while the urinary CrossLaps increased in proportion to a decrease in BMI. Both markers were normalized in patients whose BMI was between 16.4 and 18.5 kg/m2. The ratio of urinary CrossLaps to serum osteocalcin correlated with BMI (r= -0.664, P<0.0001). We conclude that the body weight history is the most important predictor of the presence of osteoporosis as well as of recovery The BMD of patients does not increase to the normal range even several years after the recovery from this disorder, and they remain a high-risk group for osteoporosis in the future.

Age-dependent decline in cortisol levels and clinical manifestations in patients with ACTH-independent Cushing's syndrome

OBJECTIVE

Adrenocortical cells change with age in both subcellular morphology and level of steroidogenesis. This study evaluates the influence of aging on hypercortisolism and clinical manifestations in patients with ACTH-independent Cushing's syndrome due to a cortisol-secreting adrenal adenoma (CS).

DESIGN

Restrospective study.

PATIENTS

Thirty-six (33 females and 3 males) with CS. 31 healthy controls were age- and sex-matched to CS patients.

MEASUREMENT

Patient age at diagnosis was compared to the degree of hypercortisolism and clinical manifestations. The degree of hypercortisolism was estimated using serum cortisol levels and urinary free cortisol excretion. Positive clinical manifestations were quantified using 12 symptoms and signs which resulted in a clinical score for each patient. Endogenous creatinine clearance, estimated disease duration and gender were analysed as possible factors affecting adenoma-secreated cortisol.

RESULTS

Patient age correlated negatively with serum cortisol level (r = -0.417, P = 0.0107, n = 36) and urinary excretion of free cortisol (r = -0.613, P = 0.0002, n = 31). Analysis of Spearman's rank correlation showed that the clinical score decreased with age (rho = -0.631, P = 0.0004, n = 33). Oedema, weakness/myopathy, hirsutism, striae and psychological changes were infrequent symptoms in the elderly. Using stepwise multiple regression analysis, we estimated the clinical score (Y) by factors of serum cortisol levels (X1:nmol/l), age (X2: years of age) and gender (X3: gender; female = 1, male = 0), i.e. Y = 4.771 + 0.004 X1 - 0.064 X2 + 2.548 X3 (r = 0.743, P < 0.0001, n = 33). Results suggested that aging both suppressed cortisol secretion and repressed manifestations directly as an independent factor, although its direct effect may be weak.

CONCLUSIONS

Our findings indicated the importance of age as a factor modulating hormonal levels and possible clinical manifestations in patients with cortisol-secreting adenomas.

Stress-induced changes of gene expression in the paraventricular nucleus are enhanced in spontaneously hypertensive rats

Heightened hypothalamic-pituitary-adrenal (HPA) axis responses have been implicated in hypertension in the spontaneously hypertensive rat (SHR), but the exact mechanisms involved are poorly understood. To determine changes in gene expression in SHR in the paraventricular nucleus (PVN), stress-induced accumulation of CRF, CRF type 1 receptor (CRFR-1) genes, and immediate-early genes were examined using in situ hybridization in young (5 weeks old) and adult (12 weeks old) stroke-prone SHR (SHRSP), compared with normotensive Wistar Kyoto (WKY) rats. Restraint stress-induced accumulation of c-fos, jun B, and NGFI-B mRNA, and CRF hnRNA in the PVN was significantly higher in young and adult SHRSP than in WKY rats at 30 min, except for c-fos in young rats. CRFR-1 mRNA expression in the PVN was also significantly higher in adult SHRSP than in WKY rats at 120 min after stress onset. CRF mRNA was increased in response to stress in young SHRSP. The basal CRF mRNA level in the PVN was significantly lower in adult SHRSP than in WKY rats. Young SHRSP exhibit greater ACTH responses to stress without significant changes in plasma corticosterone concentrations. The adult SHRSP exhibited lower baseline concentrations of corticosterone and similar corticosterone response to stress with enhanced secretion of ACTH. Overall, these results demonstrated that stress-induced activation of immediate early genes and CRF gene transcription in the PVN, and ACTH secretion is enhanced in early hypertensive, young, and adult SHRSP, suggesting that they are probably not the result of chronic alterations in blood pressure. The abnormal hypothalamic-pituitary response to stress thus appears to be related to the development of hypertension.

Establishment of a stable HL60 subline having the potential for monocytic differentiation using granulocyte-macrophage colony-stimulating factor: possible use for the study of monocytic differentiation and oxidative stress

A stable HL60 subline having the potential for monocytic differentiation was established by use of GM-CSF. HL60, a human promyelocytic cell line, has frequently been employed for research in the fields of monocytic differentiation and atherosclerosis because of its potential to differentiate into either granulocytes or monocytes. However, HL60 are frequently seen to change their phenotype during long-term culture. To date, many sublines or variants of HL60 cells have been established. However, most of them display diminished or complete loss of activities that characterize parental cells. The present study was conducted to establish a stable HL60 subline with the potential for monocytic differentiation. Firstly, a single HL60 cell was isolated by limiting dilution, and was successfully proliferated by incubation with GM-CSF. Secondly, from this population, cells were selected that had the ability to generate superoxide after VD-induced monocytic differentiation. Cells obtained in this manner (designated HL60/DU-1) exhibited expression of CD14 and CD11b and suppression of CD3 expression after monocytic differentiation. NBT positivity showed a consistent level of over 971% after a 6-day challenge with VD throughout the experimental period of 12 months. HL60/DU-1 cells, which were cryopreserved in liquid nitrogen for 6 months, thawed and re-cultured, exhibited over 97% NBT positivity. Carvedilol and probucol, which exhibit antioxidative activity, inhibited superoxide release from the differentiated HL60/DU-1 cells. HL60/DU-1 cell line is a promising model for the study of monocytic differentiation and the effects of oxygen radicals.

Serum high molecular weight form of insulin-like growth factor II from patients with non-islet cell tumor hypoglycemia is O-glycosylated

Non-islet cell tumor hypoglycemia (NICTH) is one of major causes of fasting hypoglycemia. In some patients with NICTH, insulin-like growth factor II (IGF-II) produced by and secreted from the tumors is thought to be a hypoglycemic agent. In patients with NICTH, the major form of IGF-II is high molecular weight form of IGF-II, designated as big IGF-II. The generation of big IGF-II in the NICTH syndrome is unclear. It has been reported that in the patients with NICTH big IGF-II lacks normal E-domain O-linked glycosylation, suggesting that the patient's big IGF-II might be generated by abnormal processing of pro-IGF-II. However, we have found that the apparent size of big IGF-II varies in sera from the patients with NICTH, and that there is a possibility that slower migration pattern of IGF-II might be because of a different size of sugar moiety attached to pro-IGF-II. In the present study using the sera from 10 patients with NICTH, we investigated the effect of O-glycosidase digestion on migration of IGF-II and analyzed the results by Western immunoblot. By Western immunoblot analysis the big IGF-II was reduced in size to 9.5 kDa in the enzyme-treated sera of the 10 patients with NICTH. The migration pattern is similar to that observed in sera of normal subjects after O-glycosidase digestion. These data indicate that big IGF-II from patients with NICTH is O-glycosylated, and the sizes of the sugar moiety are larger than those from normal subjects suggesting abnormal glycosylation in NICTH.

Gene expression and roles of angiotensin II type 1 and type 2 receptors in human adrenals

Although stimulation of aldosterone secretion is one of the functions of angiotensin II, the gene expression and biological significance of the angiotensin II receptor subtypes, AT1 and AT2, in the human adrenal have not been characterized. We therefore investigated the transcription levels of the receptor subtype genes and their roles in regulation of steroid secretion by human adrenals. The expression of AT1 and AT2 receptor mRNA was assessed by reverse transcription-polymerase chain reaction followed by Southern blot analysis in normal adrenocortical tissues (n = 6) and a series of adrenal tumour tissues: aldosterone-producing adrenocortical adenoma (n=6), Cushing's syndrome (n = 6) and pheochromocytoma (n = 6). The role of the two receptor subtypes in steroid secretion in vitro was examined by incubating the tissue with angiotensin II(1 microM) with or without the selective AT1 antagonist CV-11974 (1 microM). Both AT1 and AT2 receptor mRNA transcripts were demonstrated in all of the human adrenal tissues tested. Angiotensin II-induced aldosterone secretion was suppressed 50% upon the addition of CV-11974. The selective AT2 agonist CGP-42112 increased aldosterone secretion by 55% over the control, which was not suppressed by CV-11974. Angiotensin II and CGP-42112 did not affect cortisol secretion. These results suggest that both AT2 and AT1 receptors may be involved in the regulation of aldosterone secretion and tumorigenesis of the human adrenals.

Beta-adrenoceptor antagonist propranolol potentiates hypotensive action of natriuretic peptides

Beta-adrenoceptor antagonists are known to increase plasma atrial natriuretic peptide (ANP) levels despite their hypotensive action. The aim of the present study was to examine the role of the ANP system in the antihypertensive effects of a beta-adrenoceptor antagonist. We investigated the effects of propranolol (75 mg kg(-1) day(-1), p.o., 4 weeks) on the ANP system in stroke-prone spontaneously hypertensive rats. Plasma ANP levels were significantly higher in the propranolol group than in the control group. Both receptor densities and mRNA levels of ANP(C) receptor were significantly decreased in the lung as the major site of ANP clearance from the circulation. In contrast, both central venous pressure and ANP mRNA levels in the heart were not significantly different between the two groups. Under both basal and ANP-stimulated conditions, the cGMP content in the aorta was significantly greater in the propranolol group than in the control group, whereas the basal and stimulated cGMP content of the kidney was similar in the two groups. Inhibition of endogenous ANP action by a specific ANP receptor antagonist, HS-142-1, produced a greater increase of blood pressure in the propranolol group than in the control group. These results suggest potentiation of natriuretic peptide activity as a new antihypertensive mechanism of the beta-adrenoceptor antagonist propranolol.

Effects of tetramethylpyrazine, a Chinese medicine, on plasma endothelin-1 levels during acute pulmonary hypoxia in anesthetized dogs

Our study was designed to elucidate the effects of tetramethylpyrazine (TMP), a Chinese medicine, on plasma endothelin-1 (ET-1) levels in dogs with acute pulmonary alveolar hypoxia. Anesthetized dogs were used under artificial ventilation with room air or a hypoxic gas mixture (10% O2 and 90% N2) (n = 10) for 60 min. Effects of TMP (80 mg/kg) were studied by i.v. injection of TMP before exposure to hypoxia (n = 8). Mean pulmonary arterial pressure (PAPm), systemic arterial pressure (SAPm), right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and heart rate (HR) were measured. The pulmonary vascular resistance (PVR) was calculated by the equation of (PAPm-PCWP) x 8/CO. Plasma ET-1 levels were determined in the abdominal aorta and pulmonary artery by RIA. The effects of TMP on PAP and plasma ET-1 level were evaluated by using percent increase in PAPm and the change of Da-pET (delta ET) before and after hypoxia. Both PAPm and PVR were significantly elevated 5 min after acute hypoxia over a period of 60 min, whereas CO and PCWP did not change. Plasma ET-1 levels in the abdominal aorta and Da-pET showed a significant increase. Administration of TMP significantly decreased the hypoxia-induced increase in the PAPm, PVR, and delta ET. These results suggest that TMP could be a useful therapeutic agent in the treatment of pulmonary hypertension induced by acute hypoxia through decrease of plasma ET-1 levels.

Immunoreactive endothelin levels in the vitreous fluid are decreased in diabetic patients with proliferative retinopathy

Endothelin (ET) plays an important role in the pathogenesis of various cardiovascular lesions. To elucidate the pathophysiologic significance of ET in the development of diabetic retinopathy, we determined immunoreactive ET levels in the vitreous fluid collected during vitrectomy in seven patients with non-insulin dependent diabetes mellitus with proliferative diabetic retinopathy and in 10 nondiabetic subjects as controls. Immunoreactive vitreous ET levels in diabetic patients with proliferative retinopathy (7.5 +/- 3.4 pg/ml, mean +/- SD) were significantly lower than those in the nondiabetic subjects (55.0 +/- 38.1 pg/ml; p < 0.005). The decreased rather than increased immunoreactive ET levels may simply reflect severe endothelial injury to the retinal vessels caused by diabetic microangiopathy rather than an important role in diabetic retinopathy.

Tetramethylpyrazine, a Chinese drug, blocks coronary vasoconstriction by endothelin-1 and decreases plasma endothelin-1 levels in experimental animals

The purpose of this study was to investigate effects of tetramethylpyrazine (TMP), a Chinese plant-derived medicine, on coronary vasoconstriction and related electrocardiographic and histologic changes caused by endothelin-1 (ET-1), and on plasma ET-1 levels. ET-1 (75 pmol) was administered into the left coronary artery (LCA) in anesthetized closed-chest dogs with and without prior infusion of TMP (80 mg/kg). Coronary arterial diameter (CAD) was determined by coronary arteriography (CAG). Blood pressure and electrocardiogram (ECG) were monitored continuously. Histologic damage in tissues was ascertained microscopically. Plasma ET-1 and 6-keto-PGF1 levels were determined by RIA 90 min after i.v. injection of TMP (25 mg/kg; n = 5) in rabbits. Intracoronary injection of ET-1 resulted in a significant vasoconstriction of the entire vascular bed of the LCA, with a decrease in CAD of 35.9 +/- 5.7% (n = 5; p < 0.01) and ischemic changes on ECG and in tissues of endocardium, myocardium, coronary endothelial cells, and capillary vessels. Pretreatment with TMP produced a significant increase in CAD by 38.5 +/- 7.8% (n = 5; p < 0.01) and greatly suppressed the vasoconstriction produced by ET-1. The myocardial tissue damage estimated from the ratio of ischemic area for the entire area after ET-1 injection (35.6%) was completely abolished by TMP (0.6%). In addition, TMP injection induced a significant decrease in plasma ET-1 levels and an increase in 6-keto-PGF1 levels in rabbits. The Chinese medicine TMP could be a useful therapeutic agent in ischemic heart disease by suppressing coronary vasoconstriction and ischemic changes in the tissues produced by ET-1.

Immunoreactive endothelin-1 and its receptors in human adrenal tissues

To elucidate the pathophysiologic significance of endothelin-1 (ET-1) in adrenal and the mechanism for reduced responsiveness to exogenous ET-1 in aldosterone-producing adenoma (APA), we have investigated ET-1 receptors by radioligand binding assay (RBA) in human normal adrenal (NA), APA, idiopathic hyperaldosteronism (IHA), and pheochromocytoma (PHEO), immunoreactive (ir-) ET-1 content in NA, APA and PHEO by radioimmunoassay (RIA), and immunohistochemical staining of ET-1 with the peroxidase-anti-peroxidase (PAP) method in NA, APA, and PHEO. A single class of high-affinity binding sites for ET-1 was found in human NA and tumor tissues. Dissociation constant (Kd) values of ET-1 receptors were similar in NA, APA, and IHA, but maximal binding capacity (Bmax) of ET-1 receptors was lower in APA than in NA and IHA. Both Kd and Bmax in PHEO were higher than those in NA, APA, and IHA. Ir-ET-1 content in tumors of APA and PHEO were higher than in NA. Immunohistochemical staining was more intense in the tumor cells of APA and PHEO than in NA. These results suggest that the reduced response to exogenous ET-1 in APA could be related to downregulation of ET-1 receptors in the tumor. Increased ET-1 content and receptors may lead to hypersecretion of catecholamine in PHEO. ET-1 produced in normal and tumor adrenal tissues may regulate aldosterone and catecholamine secretion from adrenals in a paracrine/autocrine fashion.

Gene expression of endothelin-1 and endothelial-type nitric oxide synthase in cardiovascular tissues of stroke-prone spontaneously hypertensive rats/Izm: effects of the angiotensin-converting enzyme inhibitor aracepril

We studied target organ-protective effects of aracepril, an angiotensin-converting enzyme inhibitor, and the expression of endothelin-1 (ET-1) and nitric oxide synthase (NOS) mRNA. Aracepril (30 mg/kg) was administered orally to Izumo strain of stroke-prone spontaneously hypertensive rats (SHR-SP/Izm) for 8 weeks from 4 weeks of age and for 4 weeks from 8 weeks of age. The expression of ET-1 and endothelial NOS (eNOS) mRNA in the heart, aorta, kidneys, and brain cortex, and the expression of neuronal NOS (bNOS) mRNA in brain cortex, were analyzed by RT-PCR/Southern blotting or RNase protection analysis. Administration of aracepril markedly lowered blood pressure and decreased left ventricular weight in SHR-SP/Izm. Expression of ET-1 mRNA in the heart, kidneys, and brain was significantly enhanced in SHR/SP/Izm compared with that in WKY/Izm. Aracepril significantly decreased the expression of ET-1 mRNA, whereas there was no significant change of that in the aorta. Although expression of eNOS mRNA in the heart, aorta, and kidneys did not show any significant difference between the two strains of rats, administration of aracepril for 8 weeks significantly decreased the expression of eNOS and bNOS mRNA in brain tissue. These results suggested that aracepril may protect major target organs by modifying the expression of ET-1 and NOS mRNA, in addition to its hypotensive effect.

Serum insulin-like growth factor II in 44 patients with non-islet cell tumor hypoglycemia

Serum insulin-like growth factor II (IGF-II) was characterized by radioimmunoassay and Western immunoblot in 44 patients with non-islet cell tumor hypoglycemia (NICTH). 31 of 44 patients with NICTH had big IGF-II in sera. When the presence of IGF-II in tumors from 20 patients was investigated, IGF-II in tumors was detected in 18 patients and these patients had big IGF-II in sera. In two patients whose tumors did not contain IGF-II, big IGF-II in sera was not detected. In six patients with IGF-II in tumors, hypoglycemia disappeared and the big IGF-II decreased after successful removal of the tumors. These data indicate that the big IGF-II could be related to hypoglycemia, and that the increased serum big IGF-II suggests IGF-II-producing NICTH. Serum IGF-II levels in 31 patients with big IGF-II were greater than those in 13 patients without it (Mean +/- SEM: 723+/-54 vs. 326+/-31 ng/ml), but the elevated IGF-II levels were found in only 13 patients. Serum IGF-I levels were low in all patients with NICTH. In the 13 patients without big IGF-II, serum IGF-II levels were lower than those in the patients with big IGF-II, and serum IGF-I levels were also low. Serum IGF-II/IGF-I ratios in the patients with big IGF-II were elevated and greater than those in the patients without big IGF-II (35.0+/-2.2 vs. 11.5+/-2.4). The present data indicate that IGF-II-producing tumors are not rare in NICTH, and serum big IGF-II and IGF-II/IGF-I ratio are useful for screening patients with IGF-II-producing NICTH.