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M Katayama

Publications and source records attributed to M Katayama.

At least 55 records · Page 3Linked to original sources
PubMed2000

Developmentally and regionally regulated expression of growth hormone secretagogue receptor mRNA in rat brain and pituitary gland.

Distribution and development of growth hormone secretagogue receptor (GHS-R) mRNA expression in rat brain and pituitary gland were examined using ribonuclease protection assay. In adult male rats, GHS-R mRNA levels were highest in the pituitary gland, whereas those in the hypothalamus and hippocampus were 57 and 30% of those in the pituitary gland, respectively. Less abundant but detectable levels of GHS-R mRNA were found in the midbrain, pons, and medulla oblongata, but expression was barely detectable in the cerebellum and cerebral cortex. The expression of GHS-R mRNA was detected at late gestation (embryonic day 19) in the pituitary gland, hypothalamus, and brainstem. The mRNA levels increased with age in the pituitary gland, and decreased postnatally in the brainstem, while they remained constant in the hypothalamus during development. In contrast, GHS-R mRNA was not detectable in the hippocampus during the fetal period, but was first detected on postnatal day 7. Expression of GHS-R mRNA was also examined in the spontaneous dwarf rat (SDR), a model for isolated GH deficiency, to examine alterations in GHS-R mRNA expression in a GH-deficient state. GHS-R mRNA levels in the pituitary gland of SDRs were higher than those of control rats, suggesting negative regulation of GHS-R mRNA by GH in this region. GHS-R mRNA levels increased in the hypothalamus of female, but not in male SDRs. In contrast, GHS-R mRNA levels were not affected by GH in the brainstem and hippocampus. These results indicate that region-specific, developmentally regulated expression of GHS-R mRNA may reflect divergent physiological roles of GHS/GHS-R in distinct regions of the central nervous system and the pituitary gland.

Age Factors↗
PubMed2000

Retinoic acids and thyroid hormone act synergistically with dexamethasone to increase growth hormone-releasing hormone receptor messenger ribonucleic acid expression.

The effects of all-trans-retinoic acid (RA), 9-cis-retinoic acid (9cRA), and thyroid hormone (T3) on GH-releasing hormone receptor (GHRH-R) messenger RNA (mRNA) expression were studied using ribonuclease protection assay in the fetal rat pituitary gland and in MtT/S cells, a clonal GH cell line derived from an estrogen-induced somatotropic tumor in the rat. Although RA (1 microM), 9cRA (1 microM), or T3 (1 nM) alone showed little effect on GHRH-R mRNA expression in the MtT/S cells, each of these substances was found to act synergistically with dexamethasone (DEX; 500 nM) to increase GHRH-R mRNA expression. The effects of RAs and T3 were dose dependent, with maximum effects observed at 1 microM and 1 nM, respectively. The maximum effect of RAs or T3 was not further augmented by the addition of T3 or RAs, respectively. No apparent differences were observed in this study between the actions of RA and 9cRA. The Northern analyses showed that MtT/S cells express retinoic acid receptor alpha2 mRNA and thyroid hormone receptor beta2 mRNA, and DEX did not affect the levels of these mRNAs. This suggests that the role of DEX in enabling RAs or T3 to up-regulate GHRH-R mRNA levels is not an induction of the expression of each specific receptor for RAs and T3. The similar enhancement of DEX induction of GHRH-R mRNA by RAs or T3 was also observed in the fetal rat pituitary gland in culture, suggesting that RA and/or T3 is involved in the mechanisms responsible for the developmentally regulated expression of GHRH-R mRNA.

Alitretinoin↗
PubMed2000

Synthesis and biological activities of 4-chloroindole-3-acetic acid and its esters.

4-Chloroindole-3-acetic acid (4-Cl-IAA) and its esters were synthesized from 2-chloro-6-nitrotoluene as the starting material. The biological activities of 4-CI-IAA and its esters were determined by four bioassays. Except for the tert-butyl ester, 4-Cl-IAA and its esters had stronger elongation activity toward Avena coleoptiles than had indole-3-acetic acid. The biological activities of the methyl, ethyl and allyl esters were as strong as the activity of the free acid. All the esters, except for the tert-butyl, inhibited Chinese cabbage hypocotyl growth more than the free acid did, and all the esters induced severe swelling and formation of numerous lateral roots in black gram seedlings even at a low concentration. Furthermore, adventitious root formation was strongly promoted in Serissa japonica cuttings by all the esters. The root formation-promoting activities of the ethyl and allyl esters were about three times the value for indole-3-butyric acid which is used to promote and accelerate root formation in plant cuttings.

Avena↗
PubMed2000

[A case of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) related glomerulonephritis associated with systemic sclerosis treated by steroid pulse therapy: a case report].

A 57-year-old woman had been diagnosed as systemic sclerosis (SSc) with Raynaud's phenomenon, acrosclerosis and polyarthritis since 1995. She admitted to our hospital in July 1996 because of general fatigue, hemosputa and progressive renal insufficiency. On admission, the blood pressure was normal and laboratory findings showed elevation of the serum creatinin level and a high titer of the myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) (> 1000 EU). The renal biopsy revealed crescentic glomerulonephritis. Both renal insufficiency and high titers of MPO-ANCA improved remarkably after methylpredonisolone pulse therapy. This case was suggestive of elucidating the pathogenesis of SSc and MPO-ANCA related glomerulonephritis.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1999

Late hemorrhage from persistent pseudoaneurysm in vertebral artery dissection presenting with ischemia: case report.

BACKGROUND: Vertebral artery dissection lesions tend to resolve spontaneously, but abnormal findings such as aneurysmal-dilatation occasionally persist. However, the clinical features and pathological findings in such cases have never been verified. CASE DESCRIPTION: A 62-year-old man presented with left cerebellar infarction. Angiography showed the "pearl and string sign" in the left vertebral artery, and he was diagnosed as having left vertebral artery dissection. Repeated angiography showed persistent aneurysmal dilatation with irregular stenosis. Eleven years after the cerebellar infarction, the patient presented with a subarachnoid hemorrhage from an aneurysm of the left vertebral artery, and the lesion was explored via the left suboccipital approach. The vertebral artery was firm, making the placement of a clip impossible, so the lesion was treated by coating of the bleeding point. The patient died of pneumonia and hyperglycemia on postoperative day 15. Postmortem examination revealed an organized intramural hematoma, thickening of the intima, and fibrous degeneration of the media of the vertebral artery, a fusiform, distended thin arterial wall with intimal disruption at the aneurysmal dilatation, and arteriosclerosis of all cerebral arteries. CONCLUSION: This case indicates that persistent aneurysmal dilatation of a dissection is a pseudoaneurysm prone to rupture, and that healing of the affected vessels might be severely compromised in the presence of pathological conditions such as arteriosclerosis and disturbed intraluminal blood flow in the dissected lesions.

Aortic Dissection↗
PubMed1999

Abnormal contingent negative variation in writer's cramp.

OBJECTIVE: To investigate the physiological abnormality in writer's cramp, a focal dystonia which specifically affects writing. METHODS: We recorded brain potentials that precede hand and neck movements (contingent negative variation or CNV) in 11 patients and 11 age-matched normal subjects. A 1000 Hz tone burst (S1) was delivered to the right or left ear in random sequence, and 2 s after, a 2000 Hz tone burst (S2) was delivered to both ears simultaneously. For the response task to S2, the subjects were instructed to extend their fingers ipsilateral to the ear to which S1 was given in one experiment or to rotate the head to the side of the S1 presentation in another. All the patients had symptoms in the right hand only, and performed both tasks normally. CNV amplitudes were compared between normals and patients using unpaired t test. RESULTS: They showed normal CNV for neck movement but significantly decreased CNV amplitudes for movements both in the affected and unaffected hands. CONCLUSIONS: Our findings suggest that motor programming is specifically abnormal for the affected body part, including the asymptomatic contralateral limb, and that the clinical symptom may result from a deficient compensatory mechanism for abnormal motor programs or subroutines.

Adult↗
PubMed1999

Preparation of optically active trifluoromethylated (3'-indolyl) thiacarboxylic acids, novel plant growth regulators, through lipase-catalyzed enantioselective hydrolysis.

Among a variety of lipases tested, that obtained from Candida antarctica (SP 435) induced enantioselective hydrolysis of trifluoroethyl 5,5,5-trifluoro-4-(3'-indolyl)-3-thiapentanoate (1c). The selectivity could be increased by optimizing the reaction conditions. Thus, good selectivity was achieved (E = 37) in a buffer containing 10% dichloroethane. In order to improve the optical yields, a sequential kinetic resolution was utilized for the preparative-scale enantioselective hydrolysis of 1c using SP 435. Hydrolysis of trifluoroethyl 6,6,6-trifluoro-5-(3'-indolyl)-4-thiahexanoate (2c) with the lipase of Pseudomonas aeruginosa (LIP) in a buffer containing 20% tert-amyl alcohol at 25 degrees C gave excellent selectivity (E=357).

Journal Article↗
PubMed1999

Bone morphogenetic protein-2 promotes survival and differentiation of striatal GABAergic neurons in the absence of glial cell proliferation.

We examined the potential neurotrophic effects of bone morphogenetic protein (BMP)-2 on the survival and differentiation of neurons cultured from the rat developing striatum at embryonic day 16, a period during which the mRNAs for BMP-2 and its receptor subunits (types IA, IB, and II) were detected. BMP-2 exerted potent activity to promote the survival of striatal neurons and increased the number of surviving microtubule-associated protein-2-positive cells by 2.4-fold as compared with the control cultures after 4 days in vitro. Although basic fibroblast growth factor (bFGF) also showed relatively high activity to promote the survival of striatal neurons, transforming growth factor-beta1, -beta2, and -beta3, glial cell line-derived neurotrophic factor, or brain-derived neurotrophic factor promoted their survival weakly. Striatal neurons cultured in the presence of BMP-2 or bFGF possessed extensive neurite outgrowths, the majority of which were GABA-immunoreactive. Inhibition of glial cell proliferation by 5-fluorodeoxyuridine did not affect the capacity of BMP-2 to promote the survival of striatal GABAergic neurons. In contrast, the ability of bFGF to promote the survival of striatal neurons was inhibited significantly by the treatment of cells with 5-fluorodeoxyuridine. All these results suggest that BMP-2 exerts potent neurotrophic effects on the striatal GABAergic neurons in a glial cell-independent manner.

Animals↗
PubMed1999

Origin of the "N10" stationary-field potential after median nerve stimulation.

The scalp far-field potentials after median nerve stimulation at the wrist consist of P9, P11, P13, and P14 positive components. Earlier, Emerson et al. (1984) identified the "N10" negative potential in-between the P9 and P11 and claimed that this was not merely a passive return to the baseline after the P9 positive deflection but a distinct component reflecting a proximal brachial plexus volley. They thought N10 was a far-field potential having widespread distribution with a fixed latency. In this study we found that N10 was of higher amplitude after median nerve stimulation at the elbow than after stimulation at the wrist. Indeed the N10 latency was fixed from the lower anterior neck to the scalp, and its amplitude was maximum at the anterior lower neck. The latency of N10 was about 0.3 milliseconds longer than the Erb's potential and 0.15 milliseconds longer than the potential recorded from the lateral neck on the side of stimulation. The N10 amplitude increased in parallel with increased stimulus intensity. In order to explore the origin of the N10 stationary field potential, we designed a paired stimuli paradigm applied to the wrist (S1) and to the elbow (S2). The interstimulus interval between S and S2 was adjusted so that the timing of S2 was immediately after the traveling impulse produced by the S1 stimulus as it passed through the S2 stimulus site. This technique allowed stimulation of the anterior interosseous nerve selectively at the elbow while the median nerve originating from the wrist was undergoing refractory period. The response of (S1 + S2) - S1 showed only the N10 with absence of cervical and cortical responses, implying that N10 was activated, predominantly by the interosseous nerve, i.e., an antidromic motor volley, when the median nerve was stimulated at the elbow.

Adult↗
PubMed1999

cpmA, a gene involved in an output pathway of the cyanobacterial circadian system.

We generated random mutations in Synechococcus sp. strain PCC 7942 to look for genes of output pathways in the cyanobacterial circadian system. A derivative of transposon Tn5 was introduced into the chromosomes of reporter strains in which cyanobacterial promoters drive the Vibrio harveyi luxAB genes and produce an oscillation of bioluminescence as a function of circadian gene expression. Among low-amplitude mutants, one mutant, tnp6, had an insertion in a 780-bp open reading frame. The tnp6 mutation produced an altered circadian phasing phenotype in the expression rhythms of psbAI::luxAB, psbAII::luxAB, and kaiA::luxAB but had no or little effect on those of psbAIII::luxAB, purF::luxAB, kaiB::luxAB, rpoD2::luxAB, ndhD::luxAB, and conII::luxAB. This suggests that the interrupted gene in tnp6, named cpmA (circadian phase modifier), is part of a circadian output pathway that regulates the expression rhythms of psbAI, psbAII, and kaiA.

Amino Acid Sequence↗
PubMed1999

Regulation of growth hormone-releasing hormone receptor messenger ribonucleic acid expression by glucocorticoids in MtT-S cells and in the pituitary gland of fetal rats.

Regulation of GH-releasing hormone receptor (GHRH-R) messenger RNA (mRNA) expression was studied, with the ribonuclease protection assay, in the fetal rat pituitary gland and in MtT-S clonal cells. GHRH-R mRNA was first detected on embryonic day (E)19 and increased rapidly thereafter, to reach a maximum at E21. Incubation of E17 or E18 pituitaries with 50 nM dexamethasone (DEX), a synthetic glucocorticoid, induced GHRH-R mRNA expression, suggesting that glucocorticoids play a pivotal role in the developmental expression of this mRNA. In E19 pituitaries, 24 h treatment with DEX increased GHRH-R mRNA by 60%, and GH mRNA by 76%, but did not affect pit-1 mRNA level, suggesting that the effect of DEX is specific for expressions of GH mRNA and GHRH-R mRNA. The accumulation of GHRH-R mRNA by DEX was time dependent, and it was slightly enhanced by the protein synthesis inhibitor, puromycin (100 microM). In MtT-S cells (a pituitary cell line established from an estrogen-induced tumor), DEX induced GHRH-R mRNA expression within 2 h in a dose-dependent manner. This induction was augmented by puromycin (100 microM) or cycloheximide (3.5 microM). However, the RNA synthesis inhibitor Actinomycin D (1 microM) completely inhibited GHRH-R mRNA accumulation in response to either DEX or DEX plus puromycin, suggesting that glucocorticoids induce GHRH-R mRNA mainly through stimulation of mRNA transcription. These results suggest: that GHRH-R mRNA accumulation in the fetal pituitary gland of rats normally occurs at E19, probably because of the direct action of glucocorticoids on the pituitary gland, to stimulate GHRH-R mRNA transcription; and that the expression of glucocorticoid receptors is an important event in GH cell development in rats. Accordingly, immunocytochemical results suggest an increase in glucocorticoid receptors in immature GH cells between E17 and E18. The present results also imply that MtT-S cells may be a good model in which to further study the molecular mechanisms of the regulation of GHRH-R gene expression.

Animals↗
PubMed1999

Effect of dextran derivatives on arginine amidase activities released from isolated rabbit arteries.

In the present research we examined the levels and types of arginine amidase activities that were released from isolated rabbit arteries treated with heparin or chondroitin sulfate. Heparin accelerated the release of arginine amidase activity from the isolated rabbit ear artery, the induction was not significant; a slight increase in activity was observed in the level of arginine amidase released from isolated rabbit aorta, but no significant difference was observed. On the other hand, it was revealed that the addition of chondroitin sulfate, accelerated this release from isolated rabbit ear artery with 5% significant differences. After the addition of chondroitin sulfate, the arginine amidase activity released from isolated rabbit arteries was analyzed using various affinity adsorption methods. This analysis confirmed the presence of two types of fibrinolytic enzymes: plasminogen/plasmin activity and plasminogen activators, but no thrombin was detected.

Animals↗
PubMed1999

[Psittacosis].

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Animals↗
PubMed1999

An HIV autopsy--characterization of zidovudine-resistant subtype E HIV-1 from autopsy tissue suggests the route of infection and an alternative protocol of therapy.

This CPC concerns a 47-year-old male patient with acquired immunodeficiency syndrome (AIDS). The patient became symptomatic when he developed Pneumocystis carinii pneumonia, but recovered sufficiently to be treated as an outpatient. Two years after falling ill, he developed septic shock and died within a short time. During this period, he failed to respond to HIV drugs, and there was no improvement in his immunodeficient status. The HIV retrieved from the patient's organs at autopsy was found to be type E and to have acquired resistance to Zidovudine. It was also possible to determine the route of infection. HIV treatment guidelines are continuously being revised on the basis of HIV research and the development of new treatment plans, and at the present time, when no definitive method of treatment has yet been established, it is essential for the clinician to keep abreast of the latest information. Since HIV patients are compromised hosts, it is important to diagnose and treat other infectious complications, not only complications unique to AIDS, and we have briefly described the latest HIV therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1999

[A case of enlarged infundibular dilatation diagnosed by vertebral angiograms with carotid compression and neuroendoscope].

A case of enlarged infundibular dilatation diagnosed by vertebral angiograms with carotid compression was reported. A 57-year-old woman suffered from headache. She underwent MRA which revealed left internal carotid artery aneurysm. Left common carotid angiograms suggested a left saccular internal carotid artery aneurysm (4 mm x 6 mm) without a posterior communicating artery. However, it was confirmed to be an enlarged infundibular dilatation on left vertebral angiograms with carotid compression. It was confirmed at operation microscopically and neuroendoscopically, and the dilatation was treated by coating. When carotid angiograms reveal no posterior communicating artery, it is difficult to differentiate the origin of posterior communicating artery from internal carotid artery-posterior communicating artery junction aneurysms. Vertebral angiograms with carotid compression is useful for the differentiation for the exact diagnosis.

Aneurysm↗
PubMed1999

[Usefulness of DIC-CT in choledocholithiasis].

In order to assess the efficacy of helical CT in drip-infusion cholangiography (DIC-CT) for diagnosis of choledocholithiasis, 82 patients with biliary diseases, including 25 patients with a definite diagnosis of choledocholithiasis obtained by direct cholangiography, were investigated by DIC-CT and EUS. Comparative investigation showed that, of the 25 cases, 94.7% could be imaged by DIC-CT and 87.5% by EUS, with respective sensitivities of 94.7% and 87.5%. The specificities in both cases were 100% and accuracies were 97.8% with DIC-CT and 96% with EUS respectively. Therefore, in diagnosis the choledocholithiasis, DIC-CT displays similar diagnostic efficiency as EUS or ERC, and can be recognized as the non-invasive and useful procedure for pre-operative diagnosis of cholecystolithiasis.

Biliary Tract Diseases↗
PubMed1998

Developmental expression of NMDA receptor subunits and the emergence of glutamate neurotoxicity in primary cultures of murine cerebral cortical neurons.

Using primary cultures of murine cerebral cortices, we investigated the developmental expression of N-methyl-D-aspartate (NMDA) receptor subunits in relation to the appearance of NMDA receptor-mediated glutamate neurotoxicity. The cultures were not affected by glutamate exposure on culture days 7-9, but became sensitive to glutamate neurotoxicity on day 11. The expression of NMDA receptor subunit messenger RNAs (mRNAs) was investigated by means of reverse transcription polymerase chain reaction (RT-PCR). The epsilon 3-NR2C and epsilon 4-NR2D transcripts could not be detected in the culture. The epsilon 2-NR2B and zeta 1-NR1 subunit mRNAs, on the other hand, could be detected clearly and continuously from the culture initiation, and the epsilon 1-NR2A subunit mRNA became clearly detectable on culture day 4. The expression of these three subunits' proteins in the glutamate-insensitive stage (culture day 8) and the sensitive stage (day 11) were studied by means of Western blotting. The epsilon 2-NR2B and zeta 1-NR1 subunit proteins were clearly expressed on culture days 8 and 11, but the epsilon 1-NR2A subunit protein could hardly be detected on either day 8 or day 11. These results suggest that the glutamate neurotoxicity in the primary culture was mediated mainly by epsilon 2/zeta 1 NMDA receptors. The time lag between the protein expression of the epsilon 2-NR2B and zeta 1-NR1 subunits and the emergence of glutamate neurotoxicity may be necessary for the maturation of functional NMDA receptor systems, including heteromeric receptor formation, increase in receptor density and maturation of the postreceptor signal transduction system.

Animals↗