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Biomedical subjects

I Mori

Publications and source records attributed to I Mori.

At least 91 records · Page 5Linked to original sources
PubMed1998

Nitric oxide dependent vasodilation in young spontaneously hypertensive rats.

Conflicting evidence exists on the possible impairment of tonic nitric oxide (NO) mediated vasodilation as a causative factor in the genesis of human as well as experimental hypertension. We evaluated the tonic NO-dependent vasodilation from the pressor response to NO synthesis inhibition by NG-monomethyl-L-arginine (L-NMMA) in 9 conscious, chronically instrumented spontaneously hypertensive rats (SHR) at 12 weeks of age, ie, during the early established hypertensive stage. Nine age-matched Wistar-Kyoto rats (WKY) were used as controls. The pressor responses to L-NMMA (100 mg . kg-1 IV bolus plus 1.5 mg . kg-1 . min-1 infusion for 60 minutes) as well as to non NO-dependent pressor stimuli, namely, vasopressin (2, 4, and 8 ng . kg-1) and phenylephrine (0.5, 1, and 2 microg . kg-1) given as IV boluses, were assessed both under control conditions and during suppression of autonomic reflexes by hexamethonium (30 mg . kg-1 IV bolus+1.5 mg . kg-1 . min-1 infusion). Rather than being reduced, the pressor responses to L-NMMA were 39% and 71% larger in the control and areflexic conditions, respectively, than those observed in WKY (both P<0.01). A similar pattern was observed for the pressor responses to vasopressin (+37% and +68% in the control and areflexic conditions, respectively; both P<0.01) and phenylephrine, (+20% and +52%; both P<0.05). Additional groups of 6-week-old prehypertensive SHR (n=11) and age-matched WKY (n=11) were subjected to an identical protocol: in these animals, the pressor responses to L-NMMA were similar in each strain, as were the pressor responses to vasopressin and phenylephrine in both control and areflexic conditions. In conclusion, our observations indicate that during the developmental phase of hypertension in the SHR model, namely, during the prehypertensive as well as the early established hypertensive stage, NO-dependent vasodilation is preserved (if not enhanced) so that a putative impairment of this function provides no significant pathogenic contribution to the onset of hypertension in this experimental model.

Aging↗
PubMed1998

A cyclic nucleotide-gated channel inhibits sensory axon outgrowth in larval and adult Caenorhabditis elegans: a distinct pathway for maintenance of sensory axon structure.

The tax-2 and tax-4 genes of C. elegans encode two subunits of a cyclic nucleotide-gated channel that is required for chemosensation, thermosensation and normal axon outgrowth of some sensory neurons. Here we show that, in tax-2 and tax-4 mutants, young larvae have superficially normal axons, but axon outgrowth resumes in inappropriate regions in late larval stages. Using a temperature-sensitive mutation in tax-2, we find that tax-2 activity is required during the adult stage to preserve normal axon morphology. These results indicate that tax-2 and tax-4 are required for the maintenance of correct axon structure, and reveal an unexpected plasticity that allows C. elegans axons to be remodeled long after their initial connections have been established. TAX-2 and TAX-4 have been proposed to form a transduction channel for chemosensation and thermosensation, and tax-2 activity is required in the adult stage for normal chemotaxis to NaCl and odorants. Animals mutant for the daf-11 gene have axon phenotypes that are similar to those of tax-2 and tax 4 mutants; this axon phenotype also has a late time of action. daf-11 regulates a developmental process called dauer larva formation that is controlled by sensory stimuli, and tax-2 and tax-4 can either stimulate or inhibit dauer larva formation in different contexts.

Animals↗
PubMed1998

[Incidence of prolonged distal motor latency of the median nerve augments with the progression of diabetic polyneuropathy].

We investigated 303 diabetic patients in order to clarify the relationship between progression of diabetic polyneuropathy and conduction delay across the carpal tunnel. Distal latency ratio (DLR) was determined by comparison of distal motor latency of the median nerve with that of the ulnar nerve. Lower extremity polyneuropathy index (LPNI), expressed as a mean percentage of the normal for six indices over two nerves obtained by motor nerve conduction studies, was 82.9% on the average in the patients. Their DLR (1.44 +/- 0.24) was larger than the normal value (1.29 +/- 0.10). About 30% of the diabetics had abnormal DLR, especially in women its incidence was as high as 39%. The lower the LPNI level, the larger the incidence of abnormal DLR. In diabetic polyneuropathy patients peripheral nerves will become fragile, which might increase the incidence of conduction delay across the carpal tunnel. This phenomenon might also be called as 'double crush syndrome'.

Adult↗
PubMed1997

Somatotropic actions of the homologous growth hormone and prolactins in the euryhaline teleost, the tilapia, Oreochromis mossambicus.

It is increasingly clear that growth hormone (GH) has growth-promoting effects in fishes, which are mediated in part by the insulin-like growth factor (IGF)-I. Growth-promoting actions of prolactin (PRL) have been reported in higher vertebrates, but are less well established in teleosts. We examined the effects of injecting homologous GH or the two homologous tilapia PRLs (tPRL177 and tPRL188) on the in vitro incorporation of [35S] sulfate (extracellular matrix synthesis) and [3H]thymidine (DNA synthesis) by ceratobranchial cartilage explants and on IGF-I mRNA levels in tilapia liver. Tilapia GH (tGH) and tPRL177 stimulated sulfate uptake at the highest doses examined. Thymidine incorporation was stimulated by tPRL177. tPRL188 was without these effects. Consistent with its somatotropic actions, tGH elevated IGF-I mRNA levels in the liver. tPRL177 also elevated liver IGF-I levels. Consistent with the previously described osmoregulatory actions of GH and PRL in teleosts, we observed that tGH elevated and tPRL177 and tPRL188 lowered levels of gill Na+,K+-ATPase activity. High-affinity, low-capacity binding sites for tGH in the tilapia liver were identified. tPRL177 binds with lower affinity than tGH to these sites but can displace 125I-labeled tGH from its receptor. The ability of tPRL177 to displace tGH was similar to that of ovine GH. tPRL188 did not displace 125I-labeled tGH binding. Collectively, this work suggests that tPRL177 may possess somatotropic actions similar to tGH, but only in freshwater tilapia where tPRL177 levels are sufficiently high for it to act as a competitive ligand for GH receptors.

Animals↗
PubMed1997

Effect of theophylline on adaptation of the heart to myocardial ischemia during percutaneous transluminal coronary angioplasty in patients with stable angina pectoris.

This study was designed to examine whether theophylline, an adenosine receptor antagonist, affects cardiac adaptation to ischemia during progression of repetitive balloon inflations of percutaneous transluminal coronary angioplasty (PTCA). Theophylline abolished this cardiac adaptation, suggesting that endogenous adenosine is a key mediator for cardiac adaptation during PTCA.

Adaptation, Physiological↗
PubMed1997

Molecular neurogenetics of chemotaxis and thermotaxis in the nematode Caenorhabditis elegans.

Chemotaxis and thermotaxis in Caenorhabditis elegans are based on the chemical senses (smell and taste) and the thermal sense, respectively, which are important for the life of the animal. Laser ablation experiments have allowed identification of sensory neurons and some interneurons required for these senses. Many mutants that exhibit various abnormalities have been isolated and analyzed. These studies have predicted novel signaling pathways whose components include a putative odorant specific transmembrane receptor (ODR-10) and a cyclic nucleotide-gated channel (TAX-4/TAX-2) functioning in taste and thermosensation as well as in smell. The emerging picture of the mechanisms of sensory transduction in C. elegans seems to be basically similar to what is known of visual and olfactory sensory transduction in vertebrates. Thus, molecular and cellular analyses of chemotaxis and thermotaxis in C. elegans have proved useful and will continue to provide significant implications for the molecular basis of sensory systems in higher animals.

Animals↗
PubMed1997

Regulation of interneuron function in the C. elegans thermoregulatory pathway by the ttx-3 LIM homeobox gene.

Neural pathways, which couple temperature-sensing neurons to motor and autonomic outputs, allow animals to navigate away from and adjust metabolism rates in response to the temperature extremes often encountered. ttx-3 is required for the specification of the AIY interneuron in the C. elegans neural pathway that mediates thermoregulation. ttx-3 null mutant animals exhibit the same thermotactic behavioral defect as that seen with laser ablation of AIY in wild type, suggesting that AIY does not signal in this mutant. ttx-3 encodes a LIM homeodomain protein. A ttx-3-GFP fusion gene is expressed specifically in the adult AIY interneuron pair, which connects to thermosensory neurons. In ttx-3 mutant animals, the AIY interneuron is generated but exhibits patterns of abnormal axonal outgrowth. Thus, the TTX-3 LIM homeodomain protein is likely to regulate the expression of target genes required late in AIY differentiation for the function of this interneuron in the thermoregulatory pathway. The ttx-3-dependent thermosensory pathway also couples to the temperature-modulated dauer neuroendocrine signaling pathway, showing that ttx-3 specifies AIY thermosensory information processing of both motor and autonomic outputs.

Amino Acid Sequence↗
PubMed1997

Intravascular ultrasonic evidence by constant cross-sectional area of atherosclerotic plaques during coronary vasomotion in humans.

AIMS: This study aims to visualize ultrasonically deformation of atherosclerotic plaques in human coronary arteries during vasoconstriction and vasodilatation. METHODS AND RESULTS: Intravascular ultrasound detected occult atherosclerosis in angiographically normal coronary arteries of eight patients with chest pain at rest. During the acetylcholine provocative test, intravascular ultrasound monitored deformation of the atherosclerotic plaques. At the last step of the test, intracoronary injection of isosorbide dinitrate caused vasodilation. Under control, acetylcholine-treated, and isosorbide dinitrate-treated conditions, cross-sectional areas of sonolucent circle and vessel lumen were measured. Subtraction of the latter from the former gave the area of atherosclerotic plaque. In the process of vasoconstriction and vasodilation, the plaque area did not change significantly. CONCLUSION: The cross-sectional area of the atherosclerotic plaque appeared to be constant during vasomotion of human coronary arteries.

Acetylcholine↗
PubMed1997

Vascular thrombin receptor regulation in hypertensive rats.

Thrombin has been implicated as an important mediator of vascular lesion formation in atherosclerosis and restenosis. To investigate a potential role for thrombin signaling in the vascular response to hypertension, we have studied thrombin receptor (TR) expression and regulation in hypertensive rats. Aortic TR mRNA was upregulated by angiotensin II (Ang II)-induced hypertension (10.7 +/- 2.5 times control, P < .02), which correlated with a 4-fold increase in thrombin-induced constriction in isolated endothelium-denuded aortic rings. The AT1 receptor antagonist losartan normalized blood pressure and TR mRNA. Conversely, lowering blood pressure to the same degree with hydralazine did not abolish the upregulation of TR mRNA expression. When low-renin low-Ang II hypertension was induced in Dahl salt-sensitive rats, there was no detectable increase in the expression of aortic thrombin receptor mRNA. Finally, treatment with a chimeric heparin-binding form of the recombinant human Cu/Zn superoxide dismutase caused complete inhibition of TR mRNA upregulation, suggesting that an increased rate of superoxide anion production is an important signaling mechanism. Thus, increased TR expression via a redox-sensitive mechanism in the aortic smooth muscle of rats treated with Ang II represents a novel in vivo mechanism through which the hypertensive effects of Ang II are mediated.

Angiotensin II↗
PubMed1996

Mutations in a cyclic nucleotide-gated channel lead to abnormal thermosensation and chemosensation in C. elegans.

The C. elegans tax-4 mutants are abnormal in multiple sensory behaviors: they fail to respond to temperature or to water-soluble or volatile chemical attractants. We show that the predicted tax-4 gene product is highly homologous to vertebrate cyclic nucleotide-gated channels. Tax-4 protein expressed in cultured cells functions as a cyclic nucleotide-gated channel. The green fluorescent protein (GFP)-tagged functional Tax-4 protein is expressed in thermosensory, gustatory, and olfactory neurons mediating all the sensory behaviors affected by the tax-4 mutations. The Tax-4::GFP fusion is partly localized at the sensory endings of these neurons. The results suggest that a cyclic nucleotide-gated channel is required for thermosensation and chemosensation and that cGMP is an important intracellular messenger in C. elegans sensory transduction.

Amino Acid Sequence↗
PubMed1996

Temperature-sensitive parainfluenza type 1 vaccine virus directly accesses the central nervous system by infecting olfactory neurons.

Immunohistochemical investigation showed that intranasal inoculation of mice with a temperature-sensitive (ts) mutant of parainfluenza type 1 vaccine virus resulted in infection of some olfactory neurons as well as respiratory epithelial cells. It also disclosed the presence of viral antigens in glomeruli of the olfactory bulb but not in the secondary neurons (mitral and tufted cells). Polymerase chain reaction demonstrated the persistence of virus-specific nucleic acids in the olfactory bulb. These observations lead to the conclusion that parainfluenza virus, even with a ts phenotype, gains access to the central nervous system by infecting olfactory neurons.

Administration, Intranasal↗
PubMed1996

Clinical manifestations of HBsAg and anti-HCV negative chronic liver disease in Nagasaki Prefecture, Japan.

The discovery of hepatitis C virus (HCV) has enabled the diagnosis of type C chronic liver disease, which had in the past been diagnosed as part of non-A, non-B chronic liver disease. Although most cases with chronic liver disease are caused by hepatitis B virus (HBV) or HCV infection, there are still cases of non-B, non-C chronic liver disease. Forty patients with chronic liver disease, who were seronegative for hepatitis B surface antigen and antibody to HCV, were followed for a mean period of 72 months. The clinical manifestations in these patients were compared with those reported for type B and type C chronic liver disease. Of the 40 patients, 22 were diagnosed with chronic hepatitis, 14 with liver cirrhosis and 4 with hepatocellular carcinoma (HCC). Twenty-seven (67.5%) patients showed mild alanine aminotransferase activity profiles, and the natural clinical course of most patients showed a slow progression compared with that reported for type B and type C patients. The yearly incidence of HCC was 9.7% in patients with liver cirrhosis and 3.9% in chronic hepatitis. These rates were similar to those in type B or type C patients. This suggests that our population sample contained a number of patients with type B, type C or other etiologic agent(s), because 66.7% of the patients who developed HCC had some evidence of exposure to HBV or HCV. Our results suggest that more detailed and accurate tests for detecting HBV and HCV should be considered before making the diagnosis of non-B, non-C chronic liver disease, and that there is the need to reveal unknown etiologic agent(s).

Adolescent↗
PubMed1996

[A case of ureteral malacoplakia in a hemodialysis patient].

A case of ureteral malacoplakia in a hemodialysis patient is reported. A 64-year-old woman suffering from macrohematuria, was diagnosed as having a right ureteral tumor by means of computerized tomography and antegrade pyelography. Right nephroureterectomy with bladder cuff resection was performed. Pathological examination indicated malacoplakia; multiple Michaelis-Gutmann bodies were found. The patient did well postoperatively and was discharged without further complications. This case appears to be the twenty-first report of ureteral malacoplakia in the world.

Female↗
PubMed1996

[Effects of prostaglandin E1 on plasma cytokine levels during pneumonectomy].

We investigated the effect of prostaglandin E1 (PGE1) on intraoperative cytokine responses and the incidence of postoperative complications. Twenty-six patients undergoing elective pneumonectomy were randomly allocated into PGE1 group (n = 12) and control group (n = 14). The PGE1 group received continuous infusion of PGE1 during surgery at a dose of 0.02-0.03 microgram.kg-1.min-1. Blood samples were obtained after induction of general anesthesia, one and two hours after incision, and immediately after the end of surgery to measure the plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-8 (IL-8). Levels of CRP for two days after the surgery were measured and postoperative complications were recorded. Levels of TNF-alpha rose from 1.6 pg.ml-1 (mean) to 4.8 pg.ml-1 two hr after incision in the control group, while the level was suppressed in the PGE1 group (P < 0.05). No significant difference was found in IL-6 levels between the two groups. The IL-8 increased during surgery in both groups but the increase was significantly less in the PGE1 group (P < 0.05). There was no difference in CRP, and no severe postoperative complication was observed. We conclude that PGE1 administration suppresses TNF-alpha and IL-8 responses during pneumonectomy, but its effects on IL-6 and the postoperative status were not significant.

Aged↗
PubMed1995

Neural regulation of thermotaxis in Caenorhabditis elegans.

Thermal stimulus is an important environmental factor influencing animal behaviour. However, the mechanisms underlying thermosensation and thermal adaptation are poorly understood. The nematode Caenorhabditis elegans can sense a range of environmental temperatures and migrate towards the cultivation temperature on a thermal gradient. This modifiable thermotactic response provides an ideal system for studying the cellular and molecular processes involved in thermosensation and thermal information storage. We have identified neurons critical for thermotaxis by killing individual cells in live animals. The results indicate that an amphid sensory neuron, AFD, is a major thermosensory neuron. Some of the genetically defined cryophilic and thermophilic mutant phenotypes were mimicked when amphid interneurons AIY and AIZ, respectively, were killed, indicating that AIY is responsible for thermophilic movement and AIZ for cryophilic movement. We propose a neural model in which regulation of the activities of the two interneurons in opposite directions, depending on the cultivation temperature, is essential for thermotaxis.

Animals↗
PubMed1995

Improved spectrophotometric determination of uranium(VI) with 4-(2-pyridylazo)resorcinol in the presence of benzyldimethylstearyltrimethylammonium chloride.

An improved spectrophotometric determination of uranium(VI) is proposed using 4-(2-pyridylazo)resorcinol(PAR) in the presence of benzyldimethylstearyltrimethylammonium chloride(BSTAC) as a cationic surfactant. The calibration graph is linear in the range of 0.3-60 microg/10 ml uranium(VI), measuring the absorbance at 550 nm. The reproducibility for 19.0 microg/10 ml uranium(VI) is 0.57%. The third-derivative method using the third-derivative distance (d(3)A/dlambda(3)) among lambda(1) 530 nm, lambda(3) 594 nm and lambda(2) 565 nm was also investigated.

Journal Article↗
PubMed1995

An unseasonable winter outbreak of echovirus type 30 meningitis.

During the winter of late October, 1990 to March, 1991, echovirus type 30 meningitis affected 10 children aged 3-9 years of age in Mikuni, Japan. Five patients presented with constipation, four had diarrhoea, while five complained of severe abdominal pain, in addition to typical symptoms and signs compatible with aseptic meningitis. Echovirus type 30 was isolated from the CSF of nine, from the faeces of 10, and from the throats of eight children. All showed a significant antibody response to echovirus type 30 in paired samples of serum. Antigenic variation and thermostability of a representative isolate indicated some changes in virus structural proteins, possibly reflecting an altered tropism for tissues in the gastrointestinal tract.

Abdominal Pain↗