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Biomedical subjects

H Hidaka

Publications and source records attributed to H Hidaka.

At least 199 records · Page 11Linked to original sources
PubMed1995

Comparative studies of cytotoxicity and the release of TNF-alpha, nitric oxide, and eicosanoids of liver macrophages treated with lipopolysaccharide and liposome-encapsulated MTP-PE.

LPS and liposome-encapsulated MTP-PE induce liver macrophages cytotoxicity against tumor target cells and a release of TNF-alpha, nitric oxide, and eicosanoids but not a generation of superoxide anions. Neither agent elicits a formation of inositol phosphates, a change in intracellular free calcium, or a translation of protein kinase C-beta. Inhibition or down-regulation of protein kinase C does not inhibit the release of TNF-alpha and nitric oxide but inhibits the formation of prostanoids. In contrast to LPS, liposome -encapsulated MTP-PE induces an elevation of diacylglycerol mass and an enhanced expression of protein kinase C-delta. LPS, but not liposome-encapsulated MTP-PE, elicits an enhanced expression of cytosolic phospholipase A2 and a predominant formation of PGE2. Both agents elicit different responses when given to cells pretreated with one of the immunomodulators, with dexamethasone, or with PGE2. In contrast, to liposome-encapsulated MTP-PE, LPS induces only cytotoxicity when added to liver macrophages simultaneously or a maximum of 2 h before the addition of tumor target cells. The observed differences might reflect partly differences in the potencies of LPS and some liposome-encapsulated MTP-PE as immunomodulators.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1995

A novel Ca2+/calmodulin-dependent protein kinase lacking autophosphorylation activity in the rabbit heart.

We report the discovery, semi-purification and characterization of a novel Ca2+/calmodulin-dependent protein kinase (peak I kinase) using syntide 2 as a substrate from the rabbit heart. In the study of dependence of peak I kinase on the concentration of calmodulin, half-maximal activation was obtained at approx. 2.0 x 10(-7) M calmodulin. Peak I kinase did not undergo autophosphorylation. This kinase phosphorylates the synthetic peptides such as syntide 2, autocamtide-2, site 3 in a Ca2+/CaM-dependent manner, but not myosin light chain-peptide, gamma-peptide, and cAMP Response Element Binding Protein (CREB) peptide. Elongation Factor-2, alpha-casein and histone-IIIs were not phosphorylated. These data indicate that this CaM kinase is different from other identified Ca2+/calmodulin-dependent protein kinases and therefore constitutes a novel protein kinase.

Animals↗
PubMed1995

Immunohistochemical localization of neurocalcin in the rat inner ear.

Localization in the rat inner ear of neurocalcin, a three EF-hand calcium-binding protein, was examined immunohistochemically. Neurocalcin-like immunoreactivity was restricted to neurons in neuroepithelial receptor organs, while hair cells and supporting cells showed no such immunoreactivity. In the organ of Corti, both afferent and efferent nerve terminals, which formed synapses on both inner and outer hair cells, showed distinct immunoreactions. Spiral ganglion neurons and cochlear nerves were immunopositive. In the cristae ampullaris, macula utriculi and macula sacculi, afferent nerve terminals forming nerve calices or terminal boutons were strongly immunopositive. Efferent nerve terminals making synapses either on nerve calices or on hair cells showed an intense immunoreactivity. Vestibular ganglion neurons were strongly immunopositive. In electron microscopy, immunoreaction products were diffuse in the cytoplasm of ganglion neurons and nerve terminals. Neurocalcin-like immunoreactivity occurred in association with microtubules, outer mitochondrial membranes, synaptic vesicles and synaptic membranes. It is thus likely that neurocalcin is involved in neural functions in each type of afferent and efferent transmission in the inner ear.

Animals↗
PubMed1995

Neurocalcin-immunoreactive receptor cells in the rat olfactory epithelium and vomeronasal organ.

Occurrence of neurocalcin, a calcium-binding protein with three EF hand motifs, was examined immunohistochemically in the rat olfactory epithelium and vomeronasal organ epithelium. Immunoreactivity was detected in receptor cells in these epithelia. Immunoreactions were distributed in cytoplasm associated with outer mitochondrial membrane, endoplasmic reticulum and microtubules. Olfactory and vomeronasal nerve fibers in the lamina propria exhibited immunoreactivity. Neurocalcin may participate in calcium signalling and cytoskeletal arrangement in receptor cells.

Animals↗
PubMed1995

Differential distribution of six calcium-binding proteins in the rat olfactory epithelium during postnatal development and adulthood.

Odorant stimulation of receptor cells results in a calcium influx that activates the transduction pathway. Ca2+ acceptors, such as calmodulin, may mediate between the change in intracellular calcium and the conductance mechanism underlying the initial electrical event. Ca2+ acceptors also may participate in subsequent processing of olfactory information. The identification and characterization of these molecules, therefore, should provide important information about the complex signal transduction pathway involving calcium in olfaction as well as other sensory systems. The present study describes the distribution of six calcium-binding proteins in the rat main olfactory epithelium during postnatal development to determine when different Ca2+ acceptors can be detected and whether they segregate into different layers or portions of the epithelium. Calmodulin, calretinin, calbindin-D28k, neurocalcin, and recoverin were detected immunohistochemically in olfactory receptors but not in basal cells. S-100 immunoreactivity was restricted to glial cells primarily around the cribriform plate. During postnatal development (from P1 to P20), calmodulin, calretinin, calbindin-D28k, and neurocalcin formed a gradient of immunoreactivity descending from the central to the lateral areas in the nasal cavity, whereas recoverin was expressed only in sporadic, mature receptors in the proximal region of the mucosa. At P20, the immunoreactivity pattern for each calcium-binding protein was identical to the adult profile, indicating that the olfactory epithelium had reached maturity by this stage. Olfactory nerve fiber bundles displayed a differential staining pattern from P1 until adulthood for calbindin-D28k and calretinin (internal portions of bundles). Differential calmodulin immunoreactivity of olfactory nerves (large external portions of bundles) appeared at P10. The immunoreactivity of the nerve fiber bundles may reflect a further degree of organization relevant to odor discrimination.

Animals↗
PubMed1995

The long amino-terminal tail domain of annexin XI is necessary for its nuclear localization.

Annexin XI is a newly identified annexin which localizes mainly in the nucleus of rat embryonic fibroblasts. There are no typical nuclear localization signals (NLS) in the molecule. To define the region responsible for its nuclear localization, a series of mutants and chimeric cDNA were constructed. These were transiently expressed in COS-7 cells, and the subcellular distributions of the mutants and chimeric proteins were determined by indirect immunofluorescence microscopy. Wild-type annexin XI was located predominantly within the nucleus. Deletion of the N-terminal tail domain (residues 3-196) changed the distribution of the protein from the nucleus to the cytoplasm whereas deletion of the C-terminal core domain (residues 208-504) still kept the protein sorting to the nucleus. Three other mutants lacking 60-80 amino acids in the N-terminal region (residues 3-61, 61-115, and 115-197, respectively) no longer efficiently imported into the nucleus. Furthermore, Escherichia coli beta-galactosidase polypeptide was efficiently localized to the nucleus only when fused with the whole N-terminal region of annexin XI (residues 1-207), not with part of the N-terminal region. In primary cultured rat hepatocytes, annexin XI was distributed in the cytoplasm but not in the nucleus. These results suggest that the whole N-terminal tail domain of annexin XI is necessary and sufficient for its nuclear localization, and may function as NLS in a cell-type specific manner.

Animals↗
PubMed1995

S100 beta is a target protein of neurocalcin delta, an abundant isoform in glial cells.

To clarify the function of neurocalcin delta, an isoform found abundantly in glial cells, we attempted to find its target proteins by using neurocalcin delta-affinity chromatography and the 125I-neurocalcin delta gel-overlay method. The 10, 14, 27, 36 and 50 kDa bands found on SDS/PAGE bound to 125I-neurocalcin delta, and 10, 11, 19, 24, 26, 50 and 70 kDa proteins were eluted from a neurocalcin delta-affinity column in a Ca(2+)-dependent manner. Sequence analysis of proteolytic peptides revealed the following identities: S100 beta (10 kDa), S100 alpha (11 kDa), myelin basic protein (19 kDa), glyceraldehyde-3-phosphate dehydrogenase (36 kDa) and tubulin beta-chain (50 kDa). A zero-length cross-linking study indicated that 1 mol of S100 beta bound to 1 mol of neurocalcin delta. With the gel-overlay method, purified S100 beta protein and calcyclin bound to 125I-neurocalcin delta whereas calgizarrin and calvasculin, other members of the S100 family, did not. These findings suggest that S100 beta is one of the target proteins of neurocalcin delta, and the neurocalcin delta-S100 beta complex may be involved in Ca(2+)-signalling in the glial cell.

Amino Acid Sequence↗
PubMed1995

Localization of neurocalcin-like immunoreactivity in rat cranial motoneurons and spinal cord interneurons.

Neurocalcin (NC) is a calcium-binding protein with at least three putative calcium-binding domains called EF-hands. In this study, the distribution of neurocalcin-like immunoreactivity (LI) was examined in the rat motor system. Motoneurons in the III, IV and VI cranial nerve nuclei were NC-immunoreactive (IR) and strong labelling was seen in the nerve bundles and in the myoneural junctions in all extraocular muscles. In the ventral horn of the spinal cord, interneurons were NC-IR, whereas motoneurons, identified by Fluorogold tracing, were unlabelled. A large number of NC-IR neurons was present in the dorsal horn. NC-IR nerve fibers were seen in the ventral roots and, more abundantly, in the dorsal roots. The present results demonstrate NC-LI in the supraspinal motoneurons and spinal cord interneurons, both of which are fast-firing neurons. Provided neurocalcin regulates the concentration of free intracellular Ca2+, it may participate in several cellular functions in the fast-firing neurons.

Animals↗
PubMed1995

Elucidation of the protein kinase C-dependent apoptosis pathway in distinct subsets of T lymphocytes in MRL-lpr/lpr mice.

MRL-lpr mice are severely impaired in the Fas pathway of apoptosis induction. We here evaluate another pathway of apoptosis induction in MRL-lpr mice which is protein kinase C (PKC) dependent. Despite the defect of the Fas pathway, apoptosis developed during culture in vitro in splenic T lymphocytes from MRL-lpr mice more extensively than in T lymphocytes from MRL-(+/+) mice. Apoptosis induction in the former cells was then found to be greatly promoted by PKC inhibitor H-7, and partially prevented by PKC activator phorbol 12-myristate 13-acetate (PMA). High sensitivity to H-7, but not to PKA inhibitor HA 1004, of these cells for apoptosis induction was confirmed by detailed time course and dose-dependency experiments of the drug effect. Population analysis showed that both CD4+ T lymphocytes and CD8+ T lymphocytes from MRL-lpr mice were highly sensitive to H-7, whereas CD8+ T lymphocytes, but not CD4+ T lymphocytes, from MRL-(+/+) mice were susceptible to the reagent. Interestingly, B220+ Thy-1+ CD4-CD8- T lymphocytes from MRL-lpr mice were most sensitive to H-7 for apoptosis induction. Correspondingly, the membrane-translocated activated PKC-alpha level in splenic T lymphocytes from MRL-lpr was more extensively up-regulated by PMA than in splenic T lymphocytes from MRL-(+/+). These results suggest that some signal consistently activates PKC in MRL-lpr T lymphocytes, and this event is needed for survival of these cells. On the other hand, CD4+ CD8+ thymocytes were deleted by apoptosis in culture with PMA, whether these thymocytes were from MRL-lpr mice or MRL-(+/+) mice. This finding suggested that the apoptosis induction pathway linked to PKC activation is intact in CD4+ CD8+ thymocytes from the Fas-defective MRL-lpr mice. We conclude from these results that the PKC-dependent signal pathways for either cell death or cell activation are intact or even accelerated in lpr mice, which could both compensate for the loss of the Fas pathway and promote the generation of autoreactive T lymphocytes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Protein kinase A inhibitors enhance radiation-induced apoptosis.

In addition to a role for de novo protein synthesis in apoptosis we have previously shown that activation of a protein phosphatase or loss of activity of a kinase is also important in radiation-induced apoptosis in human cells [Baxter, and Lavin (1992): J Immunol 148:149-1954]. We show here that some inhibitors of protein kinases exacerbate radiation-induced apoptosis in the human cell line BM13674. The specific protein kinase A inhibitor isoquinoline sulfonamide (20 microM) gave rise to significantly increased levels of apoptosis at 2-6 h postirradiation compared to values after radiation exposure only. The same concentration of isoquinolinesulfonamide, which was effective in increasing apoptosis, reduced activity markedly. A 66% inhibition of cyclic AMP-dependent protein kinase A activity occurred in unirradiated cells at this concentration of H89 and activity was reduced to 58% in irradiated cells. Calphostin C, a specific inhibitor of protein kinase C, at a concentration of 0.1 microM, which caused 68% inhibition of enzyme activity in irradiated cells, failed to enhance the level of radiation-induced apoptosis. Other kinase inhibitors did not lead to an additional increase in apoptosis over and above that observed after irradiation. The results obtained here provide further support for an important role for modification of existing proteins during radiation-induced apoptosis.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Oxyhemoglobin enhancement of vasopressin-induced constriction in rat cerebral arterioles.

This study was undertaken to determine the effects of oxyhemoglobin on vasopressin-induced responses in cerebral arterioles. Rat intracerebral arterioles about 60 microns in diameter were isolated and cannulated using pipettes. Changes in diameter secondary to the extraluminal application of drugs were monitored through a video micro-scaler. Vasopressin produced a triphasic, dose-dependent response consisting of vasodilation (10(-11) M), vasoconstriction (10(-9)-10(-8) M) and a decrease in vasoconstriction (10(-7)-10(-6) M). Pretreatment with oxyhemoglobin (10(-5) M) abolished the vasodilation induced by the lower dose vasopressin and doubled the vasoconstriction induced by the higher dose. The combination of L-arginine (10(-4) M) and superoxide dismutase (600 U) restored low-dose vasopressin vasodilation and suppressed high-dose vasoconstriction in oxyhemoglobin-pretreated arterioles, while they showed little effect when used singly. This study indicates that oxyhemoglobin enhances vasopressin-induced constriction of intracerebral arterioles and these effects can be inhibited by the combination of L-arginine and superoxide dismutase.

Animals↗
PubMed1995

Regional differences in cerebral vasomotor control by nitric oxide.

Regional differences in the role of nitric oxide in cerebral vasomotor control were investigated with a nitric oxide synthesis inhibitor, NG-monomethyl-L-arginine, or a precursor of nitric oxide, L-arginine using both dog cerebral angiography for the larger artery study and rat isolated arterioles for the microcirculation study. NG-monomethyl-L-arginine (10 mumol) constricted the dog cerebral arteries, by 15.6%, 17.5%, and 27.3% in the middle cerebral, anterior cerebral, and basilar arteries, respectively. The greater constriction of the basilar artery did not reach statistical significance. However, L-arginine (100 mumol) produced significantly greater dilation of basilar arteries than the middle cerebral or anterior cerebral (31.3% vs. 16.7% or 13.1%). NG-monomethyl-L-arginine at 10(-3) M constricted rat arterioles originating from basilar arteries significantly more than the middle cerebral arteries (23% vs. 14%). L-arginine at 10(-3) M dilated rat arterioles from basilar arteries significantly more than from the middle cerebral artery (24 vs. 11%). These findings suggest that the roles of nitric oxide in vasomotor control differs by region in the brain, and it may be greater in vessels of the posterior than of the anterior circulation.

Animals↗
PubMed1995

Hippocalcin in rat retina. Comparison with calbindin-D28k, calretinin and neurocalcin.

The post-natal developmental expression in rat retina of four calcium-binding proteins belonging to the calmodulin-troponin-C family was investigated by immunohistochemistry using anti-calbindin-D28k, anti-calretinin, anti-hippocalcin and anti-neurocalcin polyclonal antibodies on paraffin sections from Wistar rat retinae aged from post-natal days 1 (P1), 5 (P5), 10 (P10), 20 (P20) to adulthood (8 weeks). Immunoblot using anti-hippocalcin and homogenates proteins from retina, cerebellar cortex, hippocampus and cerebellum was also performed. Hippocalcin immunoreactivity in adult rat retina was demonstrated by both immunohistochemistry and Western blot. During post-natal development, calbindin-D28k, calretinin and neurocalcin immunoreactivity were detected at P1 in ganglion cells, whereas hippocalcin immunoreactivity was seen later at P5 in this cell layer. In the amacrine cell layer, neurocalcin immunoreactivity was detected at P5 and hippocalcin at P10. Calbindin-D28k was labelling the immature horizontal cell, calretinin was detected in nearly all ganglion cells and in some amacrine cells since P1. These three calcium-binding proteins do not seem to play a role in synaptogenesis which takes place later. We confirmed that calbindin-D28k appeared to be a good marker for horizontal cells. The presence of hippocalcin, a myristoylated calcium-binding protein belonging to the recovering subfamily and previously localized in few brain areas has been detected for the first time in retina.

Animals↗
PubMed1995

The structure of calcyclin reveals a novel homodimeric fold for S100 Ca(2+)-binding proteins.

The S100 calcium-binding proteins are implicated as effectors in calcium-mediated signal transduction pathways. The three-dimensional structure of the S100 protein calcyclin has been determined in solution in the apo state by NMR spectroscopy and a computational strategy that incorporates a systematic docking protocol. This structure reveals a symmetric homodimeric fold that is unique among calcium-binding proteins. Dimerization is mediated by hydrophobic contacts from several highly conserved residues, which suggests that the dimer fold identified for calcyclin will serve as a structural paradigm for the S100 subfamily of calcium-binding proteins.

Amino Acid Sequence↗
PubMed1995

Effects of an HMG-CoA reductase inhibitor, pravastatin, and bile sequestering resin, cholestyramine, on plasma plant sterol levels in hypercholesterolemic subjects.

To study exogenous sterol metabolism during the suppression or stimulation of cholesterol biosynthesis induced by treatments for hyperlipidemia, we determined plasma plant sterol concentrations before and after administration of an HMG-CoA reductase inhibitor, pravastatin, and compared these with changes in these plasma sterol levels by the bile-sequestrating resin, cholestyramine. The effects of the drugs were also studied in a sitosterolemic patient who has had increased plasma levels of plant sterols. Plasma cholesterol levels determined by the HPLC method were decreased significantly after administration of pravastatin. Plasma plant sterol (sitosterol and campesterol) as well as cholestanol concentrations were also significantly reduced. Cholestyramine administration decreased plasma levels of cholesterol, but did not change those of plant sterols in the hypercholesterolemic subjects. Pravastatin had little effect in a sitosterolemic patient on plasma levels of sterols, where cholestyramine decreased the plasma levels of both cholesterol and cholestanol. These results indicate that treatment with the HMG-CoA reductase inhibitor decreases plasma plant sterol concentrations, and suggest that the increased plasma plant sterol levels in sitosterolemia might not be due to the decreased cholesterol biosynthesis in vivo.

Acyl Coenzyme A↗
PubMed1995

Prophylaxis of genetically determined diabetes by diazoxide: a study in a rat model of naturally occurring obese diabetes.

The study was carried out using a new rat model of naturally occurring obese, nonketotic diabetes, Otsuka Long-Evans Tokushima Fatty rat (Kawano et al., Diabetes 41: 1422-1428, 1992), which closely resembles obese noninsulin-dependent diabetes in human. At the age of 3.5 wk, body weight, glucose tolerance and plasma insulin level after glucose load were normal in Otsuka Long-Evans Tokushima Fatty rats, indicating the animals are at nonobese, prediabetic phase. At this age, however, glucose-stimulated insulin release by pancreatic islets in vitro was abnormally exaggerated whereas the islet insulin content and glucose metabolism by the islet cells were normal. Administration of diazoxide (0.2% in diet), an inhibitor of insulin secretion, to Otsuka Long-Evans Tokushima Fatty rats from the age of 4 to 12 wk completely prevented the development of obesity and insulin resistance, which was accompanied by marked improvement of glucose tolerance and disappearance of exaggerated B cell response to glucose in vitro. This is the first report of successful pharmacological prevention of genetically determined obese diabetes.

Animals↗
PubMed1995

Plant annexin form homodimer during Ca(2+)-dependent liposome aggregation.

The annexin (p35) was isolated from the fruits of green pepper (Capsicum annum). The partial amino acid sequence of p35 was analyzed. p35 had an endonexin fold as annexin consensus sequences. Purified p35 had other annexin like characters such as strongly bind to phosphatidylserine and phosphatidylinositol, phospholipase A2 inhibition and liposome aggregation. The zero-length crosslinking assay revealed that p35 formed a homodimer during Ca(2+)-dependent liposome aggregation.

Amino Acid Sequence↗