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Biomedical subjects

H Hidaka

Publications and source records attributed to H Hidaka.

At least 127 records · Page 7Linked to original sources
PubMed1997

Isoform-specific activation and structural diversity of calmodulin kinase I.

We earlier confirmed that there are isoforms of Ca2+/calmodulin (CaM)-dependent protein kinase I (CaM kinase I) (CaM kinase Ibeta1 and Igamma) beside CaM kinase Ialpha by cDNA cloning (Yokokura, H., Terada, O., Naito, Y., and Hidaka, H. (1997) Biochim. Biophys. Acta 1338, 8-12). Here, we demonstrate the existence of an isoform-specific activation mechanism of CaM kinase I and alternative splicing specifically regulating CaM kinase I (CaM kinase Ibeta2) in the central nervous system. To cast light on isoform structure-enzyme activity relationships, CaM kinase Ibeta1, Ibeta2, and Ialpha were expressed separately using a baculovirus/Sf9 cell expression system. The novel CaM kinase Ibeta2 isoform demonstrated similar catalytic activity to those of CaM kinase Ibeta1 and Ialpha. Interestingly, CaM kinase Ibeta1 and Ibeta2 both can activate CaM kinase Ialpha activity via phosphorylation at Thr177. Reverse transcribed-polymerase chain reaction analysis showed that CaM kinase Ibeta2 is dominant in the cerebrum and cerebellum, whereas CaM kinase Ibeta1 is present in peripheral tissues such as liver, heart, lung, kidney, spleen, and testis. CaM kinase Ibeta2 was also detected with an anti-CaM kinase Ibeta2 antibody in PC12 cells. The results indicate that alternative splicing is a means for tissue-specific expression of CaM kinase Ibeta. Thus the Thr177 residue of CaM kinase Ialpha is phosphorylated by not only CaM kinase kinase but also CaM kinase Ibeta for activation of the enzyme.

Amino Acid Sequence↗
PubMed1997

Chemical oxidation and DNA damage catalysed by inorganic sunscreen ingredients.

Titanium dioxide (TiO2) has been noted (US Federal Register, 43FR38206, 25 August 1978) to be a safe physical sunscreen because it reflects and scatters UVB and UVA in sunlight. However, TiO2 absorbs about 70% of incident UV, and in aqueous environments this leads to the generation of hydroxyl radicals which can initiate oxidations. Using chemical methods, we show that all sunscreen TiO2 samples tested catalyse the photo-oxidation of a representative organic substrate (phenol). We also show that sunlight-illuminated TiO2 catalyses DNA damage both in vitro and in human cells. These results may be relevant to the overall effects of sunscreens.

Catalase↗
PubMed1997

Beraprost sodium, an analogue of prostacyclin, induces the expression of mitogen-activated protein kinase phosphatase and inhibits the proliferation of cultured mesangial cells.

Beraprost sodium, an analogue of prostacyclin, increases intracellular cyclic adenosine monophosphate (cAMP) in cultured glomerular mesangial cells. We examined the effect of beraprost on mesangial cell proliferation. Beraprost was able to inhibit fetal bovine serum-stimulated proliferation of mesangial cells in concentrations enough to increase cellular cAMP. By northern blot analysis, beraprost induced the expression of MKP-1, a mitogen-activated protein kinase phosphatase, in a dose- and time-dependent manner, similarly to dibutyryl cAMP and adrenomedullin. These results indicate that beraprost inhibits the proliferation of mesangial cells and one of the mechanisms might be cAMP-dependent induction of MKP-1.

Animals↗
PubMed1997

Protein kinase C alpha-mediated chronic signal transduction for immunosenescence.

In CD2/protein kinase C alpha (PKC alpha)-overexpressing human CD2/rabbit PKC alpha transgenic mice, an aging-dependent increase in PKC alpha expression and a decrease in proliferative responsiveness of splenic T cells were promoted. We found that an aging-associated accumulation of CD44(high) CD45RB(low) memory CD4+ T cells in exchange for CD44(low) CD45RB(high) naive CD4+ T cells was promoted in transgenic mice. A disequilibrium between Ag-dependent generation and subsequent elimination of memory T cells in these mice was shown to underlie this phenomenon. When stimulated with Ag, the PKC alpha transgenic mice responded poorly regarding Ab production and produced cytokines biased for high IFN-gamma/IL-12 and low IL-4/IL-10 levels. These results prove, for the first time, a causal role for chronic signal transduction through PKC alpha in aging-associated immunodysfunction and provide the first animal model for genetically promoted immunosenescence.

Aging↗
PubMed1997

Effects of adrenomedullin on rat cerebral arterioles.

The effects of adrenomedullin on isolated rat intracerebral arterioles were investigated and compared with those of calcitonin gene-related peptide (CGRP) and amylin. Adrenomedullin produced dose-dependent vasodilation (maximum dilation 27.1 +/- 2.1% at 3 x 10(-7) M, median effective dose (EC50)) 1.6 x 10(-9) M). CGRP produced similar vasodilation (19.8 +/- 4.1%) at 10(-7) M with a lower EC50 of 2.8 x 10(-11) M. Amylin did not cause vasodilation at concentrations up to 10(-6) M. Adrenomedullin-induced vasodilation was significantly suppressed by CGRP-(8-37). These data suggest that adrenomedullin is a potent vasodilator for arterioles in the cerebral microcirculation that acts through CGRP receptors.

Adrenomedullin↗
PubMed1997

Immunocytochemical detection and spatial distribution of myosin light-chain kinase in preimplantation mouse embryos.

As a follow-up to our previous study on the role of myosin light-chain kinase (MLCK), a Ca2+/calmodulin-dependent enzyme, in the development of preimplantation mouse embryos, we examined the presence and pattern of distribution of MLCK during preimplantation development of the mouse by whole-mount, indirect immunocytochemistry and by Western blotting, using a monoclonal antibody against MLCK. At all stages of preimplantation development, the nucleus was brightly stained with an unstained region around the nucleus, and regions near the cell membrane were also brightly stained. Using the optical sectioning capability of the confocal laser scanning microscope, we found that, up to the eight-cell stage, the regions of cell contact were mostly unstained, but along with the process of compaction, cell contact regions showed a clear staining pattern along with clearing of the cytoplasm. During formation of the blastocyst, a ring of immunofluorescence was found at the margin of the blastocoel. In the blastocyst, cells of the inner cell mass were less immunofluorescent than trophectoderm cells. These staining results appear to be due to specific immunoreaction between MLCK and the antibody, because the staining patterns were abolished when the antibody was preabsorbed by MLCK purified from chicken gizzard smooth muscle. In Western blotting of blastocysts, we found a band at 130 kD. We also show by immunoblotting and immunohistochemistry of various mouse tissues that the antibody used in this study has cross-reactivity to MLCK of various muscle and non-muscle tissues of the mouse. The presence and spatial distribution of MLCK at various stages of preimplantation development of the mouse suggest that it could play a crucial role in the regulation of the contractile events involved in the initial differentiation that occurs during formation of the mouse blastocyst.

Animals↗
PubMed1997

Isolation and comparison of rat cDNAs encoding Ca2+/calmodulin-dependent protein kinase I isoforms.

For possible multiple isoforms of Ca2+/calmodulin-dependent protein kinase I (CaM kinase I), only one cDNA (CaM kinase I alpha) hitherto has to been cloned. By screening of embryonic (E18) rat brain cDNA libraries, we have now isolated two additional examples (CaM kinase I beta and gamma). Northern blot analysis revealed CaM kinase I alpha to predominate over I beta and gamma in rat brain. Analysis of the tissue distribution of the isoforms by reverse transcription-polymerase chain reaction (RT-PCR) protocols demonstrated CaM kinase I alpha in a variety of tissues while the expression of CaM kinase I beta and gamma was more limited to the brain. The obtained results support the idea that CaM kinase I exists as a set of isoforms.

Amino Acid Sequence↗
PubMed1997

Vasodilator effects of C-type natriuretic peptide on cerebral arterioles in rats.

The vasodilator effects of C-type natriuretic peptide (CNP) were investigated in isolated rat cerebral arterioles. CNP caused dose-dependent vasodilation, maximally by 10.0 +/- 2.2% at 10(-6) M. The median effective concentration (EC50) was 5.2 x 10(-10) M. In contrast, atrial natriuretic peptide and B-type natriuretic peptide, other members of the natriuretic peptide family, produced little or no vasodilation. Pretreatment with methylene blue (10(-4) M) abolished CNP-induced vasodilation, whereas pretreatment with NG-monomethyl-L-arginine or indomethacin did not inhibit vasodilation. Thus, CNP is suggested to cause significant vasodilation in cerebral arterioles via a cyclic guanosine monophosphate-dependent mechanism.

Animals↗
PubMed1997

Identification of a specific amino acid cluster in the calmodulin-binding domain of the neuronal nitric oxide synthase.

The calmodulin (CaM) binding domain of rat neuronal nitric oxide synthase (nNOS) was analyzed using 3 synthetic peptides corresponding to different regions of the middle portion of the enzyme. One corresponding to nNOS 732-754 gave complete inhibition of NOS enzyme activity with an IC50 of about 1 microM. Kinetic analysis indicated that the inhibition was not competitive with respect to L-arginine and the peptide produced a Ca2+ dependent, electrophoretic mobility shift of CaM on 1 M urea gels. A specific hydrophobic/basic amino acid cluster in the rat nNOS sequence, Lys732 Lys Leu, that was critical for its CaM binding was also identified in this study.

Amino Acid Sequence↗
PubMed1997

Follow-up studies of sphincter-preserving operations for anal fistulas.

PURPOSE: This study was designed to evaluate and to compare the outcome of anal fistula surgery using techniques involving minimal sphincter damage (sphincter-preserving) and conventional laying open techniques. PATIENTS AND METHODS: From January 1987 to December 1993, 2,242 patients with anal fistulas were treated surgically, of whom 1,070 had sphincter-preserving operations. These included 530 patients with low intersphincteric fistulas (II L), 116 patients with high intersphincteric fistulas (II H), 73 patients with combined high and low intersphincteric fistulas, 239 patients with transphincteric fistulas (III), and 112 patients with supralevator fistulas (IV). The open method of fistula surgery was used in 1,172 patients. RESULTS: Of 1,070 sphincter-preserving operations, delayed healing occurred in 49 patients (4.6 percent) and recurrent fistula occurred in 32 patients (3 percent). By using the open method in 1,172 patients, delayed healing occurred in 10 patients (0.9 percent) and recurrence of fistula occurred in 23 patients (2 percent). Failure rates increased with increasing depth and complexity of the fistula. CONCLUSION: Sphincter function is better with sphincter-preserving fistula surgery than with the open method, although healing was delayed more commonly in sphincter-preserving operations that with the open methods, and fistula recurrence was similar with the two methods. Choice of operation depends on depth of fistula, outcome by manometry, and history of former operations.

Anal Canal↗
PubMed1997

Oxidized lipoproteins found in patients with NIDDM stimulate radical-induced monocyte chemoattractant protein-1 mRNA expression in cultured human endothelial cells.

Although oxidized low density lipoprotein (LDL) exists in plasma from diabetic patients, there are few studies on its biological activity. Thus, we investigated the biological potency of LDL plus intermediate density lipoprotein fraction isolated from 12 non-diabetic and 24 non-insulin-dependent diabetic subjects of similar age and body mass index, in order to induce monocyte chemoattractant protein-1 (MCP-1) mRNA expression in cultured human endothelial cells. MCP-1 mRNA content in the cells exposed to the lipoproteins isolated from the diabetic patients was significantly higher than that from the control subjects (p < 0.001). The increment of MCP-1 mRNA content was positively correlated with not only HbA1c (r = 0.58, p < 0.0001) but also lysophosphatidylcholine (LPC) content in the lipoprotein (r = 0.46, p < 0.005) and was negatively correlated with diene formation lag time as a marker of oxidizability of the lipoprotein (r = -0.33, p < 0.05). Treatments of the cells with either 50 mumol/l probucol, 50 mumol/l alpha-tocopherol, or 0.1 mmol/l deferoxamine suppressed the increase in MCP-1 mRNA content induced by diabetic lipoproteins, respectively. Furthermore, the diabetic lipoproteins activated nuclear transcription factor NF-kappa B in the cells, which was inhibited by pre-treatment of cells with 50 mumol/l probucol. These data indicate that oxidatively modified lipoproteins found in diabetic plasma stimulate MCP-1 gene expression in endothelial cells. The LPC content which reflects oxidative modification of lipoprotein is at least a possible marker of biological activity to increase an atherogenic cytokine in endothelial cells.

Antioxidants↗
PubMed1997

Heterogeneous distribution of neurocalcin-immunoreactive nerve terminals in the mouse adrenal medulla.

Neurocalcin is a novel calcium-binding protein found in bovine brain tissue. We investigated immunoreactivity for neurocalcin in the mouse adrenal medulla using light and electron microscopy. The immunoreactivity was present in nerve fibers, nerve terminals, and ganglion cells in the adrenal medulla, but chromaffin cells, sustentacular cells, and Schwann cells were negative in reaction. Nerve bundles containing neurocalcin-immunoreactive fibers passed through the adrenal cortex and extended into the medulla. Immunopositive nerve fibers branched off and projected varicose terminals around the chromaffin cells. These varicose terminals contained small and large-cored vesicles and made synapses with the chromaffin cells. We performed paraformaldehyde-induced fluorescence-histochemical studies for catecholamine combined with immunohistochemical studies for neurocalcin. Neurocalcin-immunoreactive nerve terminals were more abundant at noradrenaline (fluorescent) cell-rich regions than at adrenaline (non-fluorescent) cell-rich regions. These results show that neurocalcin-immunoreactive nerves mainly innervate noradrenaline-containing chromaffin cells in the mouse adrenal medulla and that neurocalcin may regulate synaptic function in the nerve terminals.

Adrenal Medulla↗
PubMed1997

Alteration of platelet aggregation in patients with thyroid disorders.

To determine whether Graves' disease or primary hypothyroidism influence platelet function, we evaluated platelet aggregation in the platelet-rich plasma (PRP) from such patients. Platelet aggregation induced by adenosine diphosphate (ADP) in blood obtained from patients with untreated Graves' disease was significantly lower than normal, whereas that in patients with untreated primary hypothyroidism was relatively increased. The magnitude of platelet aggregation induced by collagen in both groups of patients resembled that induced by ADP. However, significant differences were evident between the two diseases (P < .05). In addition, we observed a significant inverse correlation between the extent of platelet aggregation and plasma levels of thyroid hormones (triiodothyronine [T3], thyroxine [T4], and free T3). Platelet aggregation returned to normal when the euthyroid condition was obtained in the patients following administration of antithyroid drugs or thyroid hormone. The findings are consistent with the possibility that thyroid hormones influence platelet aggregation partly via inhibition of myosin light-chain kinase (MLCK).

Adenosine Diphosphate↗
PubMed1997

Microalbuminuria is not associated with cardiovascular death in Japanese NIDDM.

To evaluate whether the presence of microalbuminuria can predict cardiovascular death in Japanese subjects with non-insulin-dependent diabetes mellitus (NIDDM), we investigated 297 Japanese NIDDM patients with Albustix-negative urine. Patients were divided into two groups, normoalbuminuric (n = 201) and microalbuminuric (n = 96) and followed until death or the end of 1994 (the mean follow-up period was 6.4 years). During the follow-up period, 28 deaths (14 normoalbuminuric and 14 microalbuminuric patients) were confirmed and only 10 deaths were attributed to cardiovascular disease (6 normoalbuminuric and 4 microalbuminuric patients). Although the age- and sex-adjusted mortality rate from all-causes in the microalbuminuric group was significantly higher than that in the normoalbuminuric group (13.5 vs. 8.2 per 1000 person-years: P < 0.05), the mortality rate from cardiovascular disease was not significantly different between two groups (3.4 vs. 3.3 per 1000 person-years). On age-adjusted Cox proportional hazards analysis. HbA1c and triglyceride were independent risk factors in mortality from cardiovascular disease, while microalbuminuria was not associated with cardiovascular death. These results indicate that, unlike Caucasians, the presence of microalbuminuria can not predict cardiovascular death in Japanese subjects with NIDDM.

Aged↗
PubMed1997

Molecular and clinical implications of loop diuretic ototoxicity.

Recent advances in molecular biology have been applied to inner ear research. Loop diuretic ototoxicity has been suggested, but not proven, to share a common mechanism with diuretic effects on renal tubules. The discovery of the molecular nature of the Na-K-2Cl cotransporter in the cochlea provided a better understanding of loop diuretic ototoxicity. In this review, we describe clinical reports of loop diuretic ototoxicity and other information obtained by physiological, biochemical and morphological investigations related to the mechanism sensitive to loop diuretics. Based on recent evidence for the molecular nature of the Na-K-2Cl cotransporter expressed in the mammalian cochlea, the underlying mechanisms of ototoxicity induced by loop diuretics are described.

Animals↗
PubMed1997

Frequency summation observed in the human acoustic reflex.

It is known that the threshold of an acoustically induced middle-ear-muscle (MEM) reflex can be lowered by the simultaneous presentation of a second tone (facilitator), which is presented to the ipsilateral or contralateral ear at a level below the acoustic reflex threshold (ART) of the facilitator itself (Sesterhenn and Breuninger, 1976; Blood and Greenberg, 1981). In the present study, a primary elicitor and a facilitator were presented to the ear contralateral to that used for measurement of the acoustic reflex (AR), and the effects of changing frequencies and sound levels of the facilitator were investigated in human subjects with normal ears. The sound levels of facilitators, which caused a significant reduction of ART for the primary elicitors (facilitation thresholds), showed an asymmetrical pattern as a function of frequency of the facilitators. The facilitation thresholds tended to be lower when a facilitator with a frequency lower than the frequency of the elicitor (1 kHz) was used. In addition, effects of the elicitor on the masked thresholds of the facilitator were examined to observe the possible interaction between elicitor and facilitator from the viewpoint of 'spread of excitation'. The underlying mechanism of summation effects of two tones are discussed based on the possible input mechanism involved in the acoustically induced MEM reflex are.

Acoustic Stimulation↗