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Biomedical subjects

H Hidaka

Publications and source records attributed to H Hidaka.

At least 307 records · Page 17Linked to original sources
PubMed1992

Differential regulation of chromogranin B/secretogranin I and secretogranin II by forskolin in PC12 cells.

The factors which regulate the expression of the granin family of secretory proteins have yet to be completely described. The present study investigated the effects of forskolin (FSK), an activator of adenylate cyclase, on the regulation of chromogranin B/secretogranin I (CgB) and secretogranin II (SgII) mRNA levels in rat PC12 cells. PC12 cells were treated with 10 microM FSK for time points up to 48 h and were harvested for cAMP determination, RNA isolation and Northern blot analysis, or fixed in 4% paraformaldehyde for immunocytochemistry. Cellular cAMP levels peaked after two h of FSK treatment and remained elevated for 48 h. Chromogranin B mRNA increased with FSK treatment, reaching a maximum of 7-fold above control after 24 h, while the level of SgII mRNA decreased to a level of 65 +/- 10% of control after 48 h. The effects of FSK on CgB mRNA appear to be mediated by cAMP, as 8-bromo-cAMP (500 microM) resulted in a 2.8-fold increase in CgB mRNA, and H-89 (30 microM), a selective inhibitor of cAMP-dependent protein kinase, reduced the FSK-mediated response. The level of CgB was also increased in FSK-treated cells, as evidenced by immunofluorescent analysis which showed a more intense staining in PC12 cells treated with FSK for 48 h than in untreated cells. The intensity of SgII staining was diminished by FSK treatment, most likely a result of a decreased rate of synthesis as well as an increase in the release of SgII. This study demonstrated that the mRNA and protein levels of CgB and SgII are differentially regulated by cAMP in PC12 cells.

Amino Acid Isomerases↗
PubMed1992

Organization and complete nucleotide sequence of the gene encoding mouse phenylethanolamine N-methyltransferase.

Phenylethanolamine N-methyltransferase (PNMT; EC 2.1.1.28) catalyzes the conversion of norepinephrine to epinephrine, the last step of catecholamine biosynthesis. We have previously reported molecular cloning of cDNA encoding human PNMT and chromosomal localization of its gene (Kaneda et al., J. Biol. Chem., 263 (1988) 7672-7677). In this report, we isolated the chromosomal gene encoding mouse PNMT by cross-hybridization with the human PNMT cDNA. Mouse PNMT gene spanned about 1.8 kb and consisted of 3 exons. Primer extension analysis showed two putative transcription initiation sites. Northern blot analysis and reverse transcription-polymerase chain reaction (RT-PCR) revealed the expression of the mouse PNMT mRNA in brain (pons and medulla oblongata) and adrenal gland. Subsequently cDNA encoding mouse PNMT was amplified by RT-PCR and cloned into the plasmid vector. Mouse PMNT gene contained the protein-coding region of 885 bp (295 amino acids) with the predicted molecular weight of 32,627. The deduced amino acid sequence of mouse PNMT revealed the major difference in the N-terminal region, as compared to the human and bovine PNMT sequences. In the 5'-terminal region of the mouse PNMT gene, we found the existence of 23 bp direct repeat sequences, which was not observed in the corresponding regions of the human and bovine PNMT genes. The presence or absence of the direct repeats caused the major difference in the PNMT sequences among species. The typical TATA, GC, and CACCC boxes as well as several sequences homologous to glucocorticoids response elements (GRE) were located in the 5'-flanking region of the mouse PNMT gene.

Amino Acid Sequence↗
PubMed1992

Suppressive effect of vasopressin on ketosis in diabetic rats.

In order to clarify if vasopressin (VP) plays a role in the pathophysiology of hyperosmolar nonketotic diabetic coma (HNDC), VP has been infused to diabetic rats and plasma levels of glucose (PG), ketone bodies, FFA and glucagon were determined. High-dose VP infusion (1.2 U/kg/h) caused gradual elevation of PG (60%) and glucagon levels (600%), while ketone bodies showed transient decrease (20%) at 30 min. Under the suppression of endogenous glucagon secretion by constant infusion of somatostatin (100 micrograms/kg/h), high dose VP showed 25% increase in PG levels and 30% reduction of ketone body levels for the subsequent VP infusion for 1.5 hour. Low-dose VP infusion (0.06 U/kg/h) had no hyperglycemic effect, but suppressed ketosis (20%) in the same condition. There were no changes in plasma FFA concentrations, indicating no significant effect of VP on lipolysis. The results indicate that VP often elevated in HNDC may play an important role for the pathophysiology of HNDC through suppression of hepatic ketogenesis.

Animals↗
PubMed1992

Increased ketogenesis related to insulin deficiency in isolated hepatocytes from NIDDM model rats.

To investigate the hepatic ketone body metabolism in NIDDM, we studied the ketone body production rates in hepatocytes from newly developed non-obese NIDDM model rats. NIDDM model rats were prepared by intraperitoneal injection of streptozotocin at 2 or 5 days of age (STZ2, STZ5 respectively). After 10-15 weeks, ketone body production rates in hepatocytes isolated from these rats were compared with those from control rats as well as ketotic rats made by intravenous injection of streptozotocin into adult rats. Basal ketone body production rates from 0.3 mM [U-14C] palmitate in hepatocytes from control, STZ 2, STZ 5 and ketotic rats were 11.7 +/- 0.98, 14.9 +/- 0.72, 16.0 +/- 0.45, 22.8 +/- 2.32 nmole.palmitate/mg.prot/hr, respectively. These rates were stimulated by 1 microgram/ml of glucagon in control, STZ 2 and STZ 5 rats (14.1 +/- 0.99, 18.6 +/- 1.36, 18.7 +/- 0.69 nmole.palmitate/mg.prot/hr, respectively), but not in ketotic rats (22.8 +/- 2.07 nmole.palmitate/mg.prot/hr). The similar effects were observed by 1 microgram/ml of epinephrine. The basal ketone body production rates were negatively correlated to both hepatic glycogen contents and plasma IRI levels. Considering these parameters together, the extent of metabolic derangement in STZ 2 and STZ 5 rats was between that in control and ketotic rats. These results indicate that the derangements of hepatic ketone body production are related to the severity of insulin deficiency and suggest that the enhanced hepatic ketogenesis contributes in part to the elevated plasma ketone body levels in non-obese NIDDM.

Animals↗
PubMed1992

Long-term depression is induced in Ca2+/calmodulin kinase-inhibited visual cortex neurons.

To elucidate a role of Ca2+/calmodulin-dependent protein kinase II (CaMKII) in induction of long-term potentiation (LTP), KN-62, a selective inhibitor for CaMKII, was injected into layer 2/3 neurons of sliced visual cortex obtained from young rats. Tetanic stimulation (5 Hz, 1 min) applied to the white matter after the KN-62 injection induced long-term depression (LTD) of excitatory postsynaptic potentials (EPSPs) evoked by test stimulation of the white matter in 9 of the 14 cells tested. However, EPSPs evoked by test stimulation of the non-tetanized site were not changed, indicating that the induction of LTD was input-specific. Simultaneously, recorded field potentials which were derived from neurons with intact CaMKII showed LTP. These results suggest that postsynaptic CaMKII plays a role in the induction of LTP/LTD in visual cortex.

Animals↗
PubMed1992

An inhibitor of Ca2+/calmodulin-dependent protein kinase II, KN-62, inhibits cholinergic-stimulated parietal cell secretion.

Cholinergic stimulation of parietal cell secretion is mediated by an increase in intracellular calcium. KN-62, a selective inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMK II), has recently been synthesized (Tokomitsu et al. J. Biol. Chem. 265: 4315-4320, 1990). To define the role of CaMK II in parietal cell secretion, we determined the effects of KN-62 on secretagogue-stimulated acid secretion in isolated rabbit parietal cells. Pretreatment of parietal cells with KN-62 resulted in the inhibition of carbachol-stimulated [14C]aminopyrine uptake over a concentration range of 3 to 60 microM (IC50 of 20 microM). KN-62 (60 microM) reduced carbachol-stimulated aminopyrine uptake to unstimulated levels. KN-62 did not alter carbachol-stimulated increases in cytoplasmic free Ca2+ concentration. High concentrations of KN-62 (60 microM) elicited a small decrease in aminopyrine uptake stimulated by forskolin, but did not significantly inhibit histamine stimulation. A potent CaMK II activity was identified in total membrane from parietal cells. These results suggest that CaMK II may mediate cholinergic-stimulated parietal cell secretion.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

A 3',5'-cyclic adenosine monophosphate-dependent pathway is responsible for a rapid increase in c-fos messenger ribonucleic acid by adrenocorticotropin.

ACTH rapidly and transiently increases c-fos mRNA in the rat adrenals in vivo. The present investigation was undertaken in order to determine what kind(s) of second messenger systems is involved in this increase. Rat adrenal cells were grown in monolayers in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum. After 2 days of culture, cells were treated with ACTH and various agents alone or in combination. The amount of c-fos mRNA was determined by dot blot hybridization and corticosterone levels in the media were measured by RIA. ACTH (300 pg/ml) increased c-fos mRNA transiently with a peak level after 60 min. A similar increase was observed when (Bu)2cAMP (1 mM) was substituted for ACTH. Pretreatment with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline-sulfonamide (H-89), a selective inhibitor of cAMP-dependent protein kinase, suppressed both basal and ACTH-increased c-fos mRNA. H-89 also suppressed corticosterone production. On the other hand, neither 12-O-tetradecanoyl-phorbol-13-acetate (100 ng/ml) nor elevated potassium ion (50 mM) affected the amount of c-fos mRNA and corticosterone production. Furthermore, pretreatment with cycloheximide (5 micrograms/ml) increased both basal and ACTH-increased c-fos mRNA. These results indicate that ACTH increases c-fos mRNA by phosphorylation of preexisting trans-acting factor(s) via cAMP-dependent protein kinase in common with steroidogenesis.

Adrenal Glands↗
PubMed1992

Pituitary adenylate cyclase activating polypeptide and vasoactive intestinal peptide increase cytosolic free calcium concentration in cultured rat hippocampal neurons.

Recently, pituitary adenylate cyclase activating polypeptide (PACAP) was isolated from ovine hypothalamus and it was shown to stimulate adenylate cyclase in rat pituitary cells, neurons, and astrocytes. PACAP exhibits a 68% amino acid sequence homology with vasoactive intestinal peptide (VIP); however, it is 1000 times more potent than VIP in stimulating adenylate cyclase. In view of the wide distribution of PACAP and its receptor in the central nervous system, PACAP is likely to act as a neurotransmitter or neuromodulator as well. In the present study, we investigated the effects of PACAP38 on cytosolic-free calcium concentrations ([Ca2+]i) and compared these effects with those of VIP in cultured rat hippocampal neurons. Calcium concentrations, at the single cell level, were measured using fura-2, a calcium sensitive fluorescent dye, and fura-2-loaded neurons were continuously superfused at 37 C and viewed under an inverted microscope. Images of these neurons were recorded at 10-sec intervals by a video camera equipped with an Argus-50/CA system which controls the image acquisition and display. [Ca2+]i was quantitated from the intensities of fluorescence of the cells at two excitation wavelengths of 340 and 380 nm. The ratio of the intensities of emitted fluorescence (340/380 nm) was calibrated to determine [Ca2+]i. PACAP38 (0.1 nM) increased [Ca2+]i in some hippocampal neurons. As the concentration of peptide was increased from 0.1 to 10 nM, the accumulated number of hippocampal neurons responding to PACAP38 progressively increased and reached a plateau at 10 nM. Total neurons (33.0 +/- 5.3%, n = 4; 502 neurons) were found to respond to 100 nM PACAP38. The half-maximal concentration (ED50) of PACAP38 was 2.60 +/- 0.77 nM. Typically, 60-90 sec after the addition of PACAP38 (10 nM), [Ca2+]i increased from basal levels of 50-100 to 150-300 nM. VIP also increased [Ca2+]i, but required 1 microM or higher concentration for a considerable number of cells to respond. The number of hippocampal neurons responding to VIP at 1 microM was 28.9 +/- 9.8% (n = 4; 442 cells) which was comparable to the population of neurons responding to 10 nM PACAP38. The ED50 for VIP was 0.68 +/- 0.38 microM which was approximately 260 times higher than the ED50 for PACAP38. Neither 1-10 microM nitrendipine, a L-type voltage-dependent Ca2+ channel blocker, or 1 microM omega-conotoxin GVIA, a N-type voltage-dependent Ca2+ channel blocker, altered the PACAP-induced Ca2+ increment. Removal of Ca2+ from the superfusion media did not influence the PACAP38-induced increase of [Ca2+]i.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

[Molecular pharmacology of intracellular Ca2+ messenger system in cardiovascular function: development and application of selective inhibitors].

The importance of Ca2+ for the transmission of information inside living cells is well-recognized. The mobilized Ca2+ binds to the intracellular Ca2+ binding proteins to transmit the Ca2+ signal. Calmodulin is the most important Ca2+ binding protein to exert pleiotropic effects on various cellular functions by activating multiple enzymes. To determine the physiological significance of the Ca2+ messenger system, specific inhibitors are quite essential. We have been originally developing novel and selective inhibitors, and analyzing the several processes involved in information flow in the Ca(2+)-dependent regulatory system of cell functions. The aim of this review is to introduce our research strategy for the production of selective inhibitors towards calmodulin-dependent enzymes and to discuss recent progress in the understanding of the multiple calmodulin-dependent pathways that mediate the action of exogenous physiological stimuli. We summarize much of the pharmacological evidence that has led to our current knowledge of calmodulin-regulated cell functions, with emphasis on aspects that may be relevant to drug design. These H-series inhibitors are one of the most powerful tools as molecular probes for pharmacological approaches, and will shed light on the physiological significance and molecular mechanisms of the calmodulin-dependent pathways in various cell functions.

Animals↗
PubMed1992

Characterization of parathyroid hormone-related protein in the human term placenta.

To characterize parathyroid hormone-related protein (PTHrP) in the human placenta, we measured PTHrP-like immunoreactivity (PRP-LI) in the term placenta and studied the elution profiles of placental tissue extracts on Sephadex G-75 chromatography with a specific RIA. We also examined the gene expression of PTHrP mRNA by Northern blot analysis and the localization of PRP-LI in the placenta by immunohistochemistry. The amount of PRP-LI in placental extracts (n = 7) was 20.9 +/- 2.2 pg/g wet tissue (mean +/- SE). Dilution curves of placental tissue ran parallel to those of synthetic PTHrP (1-34) standards. Sephadex G-75 gel chromatography demonstrated two major PRP-LI peaks; the first peak was eluted around the molecular size between 10 kilodaltons (Kda) and 20 Kda and the other around 5 Kda. Northern blot analysis of PTHrP mRNA extracted from placental tissues showed a major hybridization signal around 18S. PTHrP immunohistochemistry showed PRP-LI staining in the cytoplasm of syncytiotrophoblasts and stroma cells (Hofbauer cells) in the term placenta. These results suggest that syncytiotrophoblasts and stroma cells in the term placenta synthesize PTHrP in two major molecular forms, 10 Kda-20 Kda and around 5 Kda.

Adult↗
PubMed1992

Hypertension and the development of complications in patients with non-insulin dependent diabetes mellitus in Japan.

Hypertension is a very frequent condition in individuals with non-insulin dependent diabetes mellitus (NIDDM) in Japan and has affected the occurrence of late diabetic complications, especially stroke and nephropathy. Despite similar characteristics of hypertension among Japanese and white patients, the effect of hypertension on the development of coronary artery disease (CAD) in these two populations is strikingly different. In white NIDDM patients, hypertension is one of the major risk factors for the development of CAD. However, CAD is an infrequent complication in NIDDM patients in Japan, even though they have hypertension, lipid abnormalities, and renal complications.

Adult↗
PubMed1992

Familial spinal xanthomatosis with sitosterolemia.

A family with multiple spinal xanthomas and sitosterolemia is described. A 48-year-old woman presented with paraplegia due to multiple intradural extramedullary tumors. The patient also showed marked tendon xanthomas and analysis of sterol composition in both plasma and the xanthoma established the diagnosis of the rare inherited metabolic disease, sitosterolemia and xanthomatosis. Two other siblings in the family presented with marked tendon xanthomas and coronary atherosclerosis, but did not show any neurological signs or symptoms. Magnetic resonance imaging (MRI) study revealed multiple intradural extramedullary tumors in spinal canals of the proband and her sister, but not in the other affected sibling (brother). This is the first report of familial occurrence of multiple extramedullary spinal tumors due to the inherited metabolic abnormality.

Cholesterol↗
PubMed1992

Effect of AT877 on cerebral vasospasm after aneurysmal subarachnoid hemorrhage. Results of a prospective placebo-controlled double-blind trial.

With the cooperation of 60 neurosurgical centers in Japan, a prospective randomized placebo-controlled double-blind trial of a new calcium antagonist AT877 (hexahydro-1-(5-isoquinolinesulfonyl)-1H-1,4-diazepine hydrochloride, or fasudil hydrochloride) was undertaken to determine the drug's effect on delayed cerebral vasospasm in patients with a ruptured cerebral aneurysm. A total of 276 patients, who underwent surgery within 3 days after subarachnoid hemorrhage (SAH) of Hunt and Hess Grades I to IV, were entered into the study. Nine patients were excluded because of protocol violation. The remaining 267 patients received either 30 mg AT877 or a placebo (saline) by intravenous injection over 30 minutes, three times a day for 14 days following surgery. Demographic and clinical data were well matched between the two groups. It was found that AT877 reduced angiographically demonstrable vasospasm by 38% (from 61% in the placebo group to 38% in the AT877 group, p = 0.0023), low-density regions on computerized tomography associated with vasospasm by 58% (from 38% to 16%, p = 0.0013), and symptomatic vasospasm by 30% (from 50% to 35%, p = 0.0247). Furthermore, AT877 reduced the number of patients with a poor clinical outcome associated with vasospasm (moderate disability or worse on the Glasgow Outcome Scale at 1 month after SAH) by 54% (from 26% to 12%, p = 0.0152). There were no serious adverse events reported in the AT877 group. This is the first report of a placebo-controlled double-blind trial that has demonstrated a significant reduction in angiographically revealed vasospasm by intravenous drug therapy.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Effects of calmodulin inhibitors on amylase secretion from rat pancreatic acini.

To investigate the role of calmodulin in stimulus-secretion coupling in pancreatic acinar cells, we studied the effects of W-7, a calmodulin inhibitor, and KN-62, a specific inhibitor of Ca2+/calmodulin-dependent protein kinase II (Ca2+/CaM kinase II), on amylase secretion from rat pancreatic acini. Calmodulin inhibitor (W-7, 100 microM) and Ca2+/CaM kinase II inhibitor (KN-62, 10 microM) reduced amylase secretion stimulated by cholecystokinin (CCK) or carbachol. W-7 and KN-62 also inhibited amylase secretion stimulated by both calcium ionophore (A23187) and phorbol ester (12-O-tetradecanoylphorbol-13-acetate, TPA). To clarify the role of calmodulin in the interaction of intracellular mediators, pancreatic acini were permeabilized with streptolysin O. Following permeabilization, amylase secretion was stimulated by submicromolar free Ca2+, and this Ca(2+)-dependent amylase secretion was enhanced by guanosine 5'-[gamma-thio]triphosphate (GTP gamma S), TPA or cyclic adenosine 3',5'-monophosphate (cAMP). W-7 and KN-62 had no effects on amylase secretion stimulated by Ca2+ alone, but inhibited the enhancement in Ca(2+)-dependent amylase secretion by GTP gamma S, TPA or cAMP. These data suggest that calmodulin plays an important role in Ca(2+)-dependent amylase secretion from pancreatic acinar cells and in the interaction between Ca2+ and other intracellular messengers.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗