Zenei Arihara

Role of urotensin II in patients on dialysis.

Urotensin II is a potent vasoconstrictor, which also has some vasodilatory properties. We investigated its expression in various tissues and in the plasma of patients with renal dysfunction. Plasma concentrations of urotensin II-like immunoreactivity were 2-fold higher in patients not on dialysis and 3-fold higher in those on haemodialysis thanin healthy individuals. Messenger RNA encoding theurotensin II precursor and the urotensin II receptor precursor were expressed in various human tissues. The peptidemight act as an important regulator in the cardiovascularand renal systems. Urotensin II antagonists could, therefore, be useful in the treatment of diseases affecting theseorgans.

Increased plasma urotensin II levels in patients with diabetes mellitus

Urotensin II (UII) is the most potent vasoconstrictor peptide, whereas it acts as a vasodilator on some arteries. We studied plasma levels of UII in diabetic patients with normal serum creatinine levels (<90 micromol/l) and the expression of UII and its receptor in cultured human vascular endothelial cells. Plasma UII levels were significantly elevated by 1.8-fold in diabetic patients without proteinuria (7.8+/-0.6 fmol/ml; P <0.0001) and 1.7-fold in those with overt proteinuria (7.3+/-0.9 fmol/ml; P =0.0018) when compared with healthy subjects (4.4+/-0.2 fmol/ml). No significant correlation was obtained between plasma UII levels and fasting blood sugar (P =0.631 and P =0.853 in non-proteinuric and proteinuric diabetic patients respectively), glycated haemoglobin levels (P =0.376 and P =0.888 respectively) or serum creatinine levels (P =0.301 and P =0.568 respectively). Reverse transcriptase-PCR analysis showed the expression of mRNAs encoding UII precursor and UII-receptor precursors in cultured human coronary artery endothelial cells and umbilical vein endothelial cells, suggesting that vascular endothelial cells are one of the sources of UII in blood. These findings suggest that elevation of plasma UII levels may be an important background factor in diabetic cardiovascular and organ complications in diabetic subjects without renal failure.

Elevated plasma levels of immunoreactive urotensin II and its increased urinary excretion in patients with Type 2 diabetes mellitus: association with progress of diabetic nephropathy

Urotensin II (UII) is the most potent vasoconstrictor peptide ever identified. In order to clarify the pathophysiological role of UII in diabetes mellitus, we examined plasma immunoreactive UII levels and urinary excretion of immunoreactive UII in 10 control subjects and 48 patients with Type 2 diabetes mellitus. The patients were divided into three groups according to the renal function: Group I with Ccr > or = 70 ml/min, group II with 30 < or = Ccr <70 ml/min and group III with Ccr <30 ml/min. Plasma immunoreactive UII levels were elevated in the three diabetic groups compared with normal controls (P <0.05). Group III patients had significantly higher plasma immunoreactive UII levels (15.9 +/- 2.2 fmol/ml, mean +/- S.E.M., n=6) by approximately 1.6-fold than did group I (10.9 +/- 0.9 fmol/ml, n=17) and group II (10.8 +/- 0.8 fmol/ml, n=25) (P <0.05). Urinary excretion of immunoreactive UII was significantly increased in group III patients (52.4 +/- 14.8 pmol/day) by more than 1.8-fold compared with control subjects, groups I and II (P <0.005). Fractional excretion of immunoreactive UII significantly increased as renal function decreased. Presence of diabetic retinopathy or neuropathy had negligible effects on plasma immunoreactive UII levels and urinary immunoreactive UII excretion. Reverse phase HPLC analyses showed three immunoreactive peaks in normal plasma extracts and multiple immunoreactive peaks in normal urine extracts. Thus, Type 2 diabetes mellitus itself is a factor to elevate plasma immunoreactive UII levels, and accompanying renal failure is another independent factor for the increased plasma immunoreactive UII levels in Type 2 diabetic patients. Increased urinary immunoreactive UII excretion in Type 2 diabetic patients with advanced diabetic nephropathy may be due not only to the elevated plasma immunoreactive UII levels but also to increased UII production and/or decreased UII degradation in the diseased kidney.

Immunoreactive orexin-A in human plasma

Orexin-A and orexin-B are newly discovered neuropeptides which are implicated in feeding behavior and arousal state. We studied immunoreactive(IR)-orexin-A concentrations in human plasma by radioimmunoassay. IR-orexin-A concentrations in plasma obtained from 17 healthy subjects in the morning were 1.94 +/- 0.24 pmol/liter (mean +/- SEM). IR-orexin-A levels in the plasma obtained at night were not significantly different from those obtained in the morning in 9 female subjects. The HPLC analysis of the plasma extract showed two immunoreactive peaks; one peak eluting in an identical position to synthetic orexin-A, and one eluting earlier. This study has shown for the first time the presence of orexin-A in human plasma.

Regional distribution of urocortin-like immunoreactivity and expression of urocortin mRNA in the human brain.

Regional distribution of urocortin-like immunoreactivity (UCN-LI) in the human brain was studied by radioimmunoassay and was compared with that of corticotropin-releasing hormone (CRH). In addition, the expression of UCN mRNA was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) method. UCN-LI was detected in every region of brain examined, including hypothalamus, pons, cerebral cortex, and cerebellum. The concentrations of UCN-LI in the human brain were approximately 3 pmol/g wet weight in any brain region, and no marked regional difference was noted. On the other hand, the highest concentrations of CRH-LI were found in the frontal cortex, temporal cortex, and hypothalamus and the lowest in the pons. Reverse phase high-performance liquid chromatography of the UCN-LI in the human brain extract showed two immunoreactive peaks; one peak eluting earlier and one in the position of synthetic human UCN. RT-PCR showed that UCN mRNA was expressed in every region of brain examined. These findings indicated that UCN and UCN mRNA were widely expressed in the human brain.

Expression of urotensin II and its receptor in adrenal tumors and stimulation of proliferation of cultured tumor cells by urotensin II.

Urotensin II is a potent vasoactive peptide, which was originally isolated from fish urophysis. We studied expression of urotensin II and its receptor mRNAs in the tumor tissues of adrenocortical tumors, pheochromocytomas and neuroblastomas. Effects of exogenously added urotensin II on cell proliferation were studied in a human adrenocortical carcinoma cell line, SW-13 and a human renal cell carcinoma cell line, VMRC-RCW. The reverse transcriptase polymerase chain reaction (RT-PCR) showed expression of urotensin II and its receptor mRNAs in all the samples examined; seven pheochromocytomas, nine adrenocortical adenomas (four with primary aldosteronism, four with Cushing syndrome and one with non-functioning adenoma), four adrenocortical carcinomas, one ganglioneuroblastoma and five neuroblastomas, as well as four normal portions of adrenal glands (cortex and medulla). Urotensin II-like immunoreactivity was detected in one of eight adrenocortical adenomas, two of four adrenocortical carcinomas, one of six pheochromocytomas, and one of five neuroblastomas by radioimmunoassay, but not in normal portions of adrenal glands (detection limit; 0.2pmol/g wet weight). Treatment with urotensin II for 24h significantly increased number of SW-13 cells (at 10(-8) and 10(-7)mol/l) and VMRC-RCW cells (at 10(-8)mol/l). These findings raise the possibility that urotensin II may act as an autocrine/paracrine growth stimulating factor in adrenal tumors.

Orexin-A in the human brain and tumor tissues of ganglioneuroblastoma and neuroblastoma.

Regional distribution of orexin-A-like immunoreactivity in the human brain and pituitary, and the presence of orexin-A-like immunoreactivity in the tumor tissues of pheochromocytomas, ganglioneuroblastomas and neuroblastomas were studied by radioimmunoassay. Expression of orexin mRNA was studied by reverse transcriptase polymerase chain reaction (PCR) method. Orexin-A-like immunoreactivity was detected in every region of human brain, but not in the pituitary. The highest concentration of orexin-A-like immunoreactivity in the human brain was found in hypothalamus (17.8 +/- 4.3 pmol/g wet weight, mean +/- SEM, n = 7), followed by thalamus, medulla oblongata, and pons. Orexin-A-like immunoreactivity was detected in the tumor tissues of ganglioneuroblastoma and neuroblastoma, but not in the tumor tissues of pheochromocytoma. Reverse phase high performance liquid chromatographic analyses of the orexin-A-like immunoreactivity in the human brain extracts and neuroblastoma extracts showed a single immunoreactive peak, which was eluted in an identical position to synthetic human orexin-A. Orexin mRNA was expressed in the hypothalamus and in the tumor tissues of ganglioneuroblastoma and neuroblastoma. These findings suggest that orexin-A is produced in the hypothalamus and transported to various brain regions via axons. In addition, this study has shown for the first time the production of orexin-A by ganglioneuroblastomas and neuroblastomas.

Plasma orexin-A-like immunoreactivity in patients with sleep apnea hypopnea syndrome.

Orexin-A (hypocretin-1), a neuropeptide produced in hypothalamus, stimulates arousal. We studied plasma concentrations of orexin-A-like immunoreactivity (orexin-A-LI) in 156 patients with sleep apnea hypopnea syndrome (SAHS) and 22 control subjects. Plasma orexin-A-LI levels were significantly decreased in 156 patients with SAHS (4.4+/-0.15 pmol/l, mean+/-S.E.) as compared with controls (5.3+/-0.45 pmol/l). The levels were decreased in parallel with the severity of sleep-related respiratory disturbance and magnitude of sleep fragmentation. These findings raise the possibility that a low plasma level of orexin-A-LI may be a marker to show the severity of the disease in patients with SAHS.

Expression of adrenomedullin mRNA in adrenocortical tumors and secretion of adrenomedullin by cultured adrenocortical carcinoma cells

Immunoreactive-adrenomedullin concentrations and the expression of adrenomedullin mRNA were studied in the tumor tissues of adrenocortical tumors. Northern blot analysis showed the expression of adrenomedullin mRNA in tumor tissues of adrenocortical tumors, including aldosterone-producing adenomas, cortisol-producing adenomas, a non-functioning adenoma and adrenocortical carcinomas, as well as normal parts of adrenal glands and pheochromocytomas. On the other hand, immunoreactive-adrenomedullin was not detected in about 90% cases of adrenocortical tumors (<0.12 pmol/g wet weight (ww)). Immunoreactive-adrenomedullin concentrations ranged from 0.44 to 198.2 pmol/g ww in tumor tissues of pheochromocytomas and were 9.2 +/- 1.2 pmol/g ww (mean +/- SD, n = 4) in normal parts of adrenal glands. Adrenomedullin mRNA was expressed in an adrenocortical adenocarcinoma cell line, SW-13 and immunoreactive-adrenomedullin was detected in the culture medium of SW-13 (48.9 +/- 1.8 fmol/10(5) cells/24h, mean +/- SEM, n = 4). On the other hand, immunoreactive-adrenomedullin was not detectable in the extract of SW-13 cells (<0.09 fmol/10(5) cells), suggesting that adrenomedullin was actively secreted from SW-13 cells without long-term storage. These findings indicate that adrenomedullin is produced and secreted, not only by pheochromocytomas, but also by adrenocortical tumors. Undetectable or low levels of immunoreactive-adrenomedullin in the tumor tissues of adrenocortical tumors may be due to very rapid secretion of this peptide soon after the translation from these tumors.

Clinical Significance of Daytime Plasma Orexin-A-Like Immunoreactivity Concentrations in Patients with Obstructive Sleep Apnea Hypopnea Syndrome

Background: Polysomnography (PSG) tests are very complicated and time consuming, despite their clinical benefits in the diagnosis of patients with obstructive sleep apnea hypopnea syndrome (OSAHS). A plasma marker would be desirable to select patients suspected of OSAHS for further PSG studies. We have recently reported that orexin-A concentrations in plasma collected immediately after waking early in the morning were significantly lower in patients with OSAHS than in controls. Objectives: We conducted the present study to assess the clinical usefulness of the measurement of orexin-A concentrations in plasma obtained in the daytime as a diagnostic predictor to screen patients with OSAHS. Methods: Blood samples were collected in the daytime from 19 male patients with suspected sleep-disordered breathing. Plasma orexin-A concentrations were measured by radioimmunoassay before performing PSG. Results: PSG was conducted in all 19 subjects. PSG showed that 14 subjects had OSAHS and 5 subjects did not. Plasma orexin-A concentrations were significantly lower in patients with OSAHS (4.9 ± 0.8 pmol/l, mean ± SE, n = 14) than in control subjects (12.3 ± 1.9 pmol/l, n = 5) (p = 0.0004). Conclusions: These findings suggest that the orexin-A concentration in plasma obtained even in the daytime may be a useful plasma marker for screening OSAHS.