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S Yamaguchi

Publications and source records attributed to S Yamaguchi.

At least 595 records · Page 33Linked to original sources
PubMed1995

Electrophysiologic correlates of age effects on visuospatial attention shift.

The effects of age on the neural processes underlying shifts in visuospatial attention were studied by non-invasive recording of brain electrical activity. Event-related evoked potentials (ERPs) were recorded in young (age 28-36 years old) and elderly (59-74 years old) subjects during a target detection task. Targets were preceded by central or peripheral informative cues, which are hypothesized to provoke voluntary and reflexive shifts of spatial attention, respectively. There were no age-related differences in the effects of cue validity on reaction times. Elderly subjects had longer reaction times to both the valid and invalid targets. The ERP recordings demonstrated that attention shift-related negativities (ARNs) were generated over the hemisphere contralateral to the central cue direction with the same amplitude in young and elderly subjects. However, the onset latency was delayed for the elderly at anterior scalp sites. Peripheral cues enhanced the N1 component (140-200 ms post-cue) over the contralateral hemisphere comparably in the two age groups. The ARNs following N1 enhancement demonstrated delayed onset and restricted scalp distributions in the elderly group compared with the young group. These results suggest that resistance of cue validity effects to aging is consistent with existence of the N1 enhancement and ARNs, even in elderly subjects. Different age effects on ERPs generated by central and peripheral cues support the notion that voluntary and reflexive mechanisms of attention shift involve distinct neural systems with different vulnerability to aging.

Adult↗
PubMed1995

Culture, gender, and self: a perspective from individualism-collectivism research.

Individualism and collectivism are often equated with independent vs. interdependent, agentic vs. communal, and separate vs. relational self-construals. Although these same concepts have been used to characterize both cultural and gender differences, a perspective of cultural evolution suggests it is unlikely. A division of labor within society may produce gender differences, but this cannot explain cultural differences. A study of self-construal involving 5 cultures (Australia, the United States, Hawaii, Japan, and Korea) shows that differences between these cultures are captured mostly by the extent to which people see themselves as acting as independent agents, whereas gender differences are best summarized by the extent to which people regard themselves as emotionally related to others.

Adolescent↗
PubMed1995

Cell proliferation and advancement of hepatocarcinogenesis in the rat are associated with a decrease in connexin 32 expression.

The expression of connexin 32 (Cx32), a major liver gap junction protein, after partial hepatectomy (PH) and during development and progression of hepatocarcinogenesis was studied in the rat. Cx32 was quantitatively analyzed by counting immunohistochemically demonstrated protein spots on the membranes of hepatocytes. Livers were sequentially examined after PH to assess the correlation with cell proliferation. For the analysis of different stages in carcinogenesis, Cx32 was assayed in N-ethyl-N-hydroxyethylnitrosamine-induced enzyme altered foci (EAF), hyperplastic nodules (HN), hepatocellular carcinomas (HCC), pulmonary metastatic HCC and transplanted HCC in relation to their degree of altered enzyme expression. Cx32 showed: (i) a rapid decrease after PH to its lowest levels during and 12 h after the S phase of cell proliferation when 5-bromo-2'-deoxyuridine (BrdU) labeling indices were examined; (ii) a progressive decrease from early preneoplasia EAF to HN and HCC, values for pulmonary metastatic and transplanted HCC being 0; (iii) clearly inverse correlations with increased BrdU index and degree of altered enzyme expression in HN, indicating that these, with the lowest Cx32 count, are closest to HCC. Therefore, the observed decrease appears linked to cell proliferation and progression of hepatocarcinogenesis, providing a reflection of cellular independence and growth advantage.

Animals↗
PubMed1995

Stimulation of phagocytosis and phagosome-lysosome fusion by glycosphingolipids from Sphingomonas paucimobilis.

Sphingomonas paucimobilis, a Gram-negative opportunistic pathogen, is actively phagocytosed by human peripheral polymorphonuclear leukocytes (PMN) in vitro. However, when live or killed cells were delipidated, the phagocytic rate was clearly decreased. Therefore, we have investigated the physiological role of membrane lipids in phagocytic processes. S. paucimobilis type strain 2395 produces four classes of acidic glycosphingolipids (GL-1, GL-2, GL-3, and GL-4) with the common components of glucuronic acid, 2-hydroxy myristic acid and d18:0 or d21:1 long-chain base. The effect of acidic glycosphingolipids on phagocytosis by PMN using killed Staphylococcus aureus cells coated with glucuronosyl ceramide (GL-1) or ceramide tetrahexoside (GL-4) was also examined. The rate of phagosome-lysosome fusion by PMN was determined by counting acridine orange-stained bacteria under a fluorescence microscope. Both phagocytosis and phagosome-lysosome fusion by PMN of glycosphingolipid-coated bacteria were stimulated markedly in a dose-dependent manner. It was noted that GL-1 or GL-4 stimulated phagosome-lysosome fusion dramatically, but synthetic lipid A did not. Superoxide anion release from PMN was enhanced significantly by the coating with synthetic lipid A at higher concentration, but only slightly with GL-1 or GL-4. Glucuronic acid was an inhibitor of phagocytosis of GL-1-coated S. aureus by PMN. The effect of acidic glycosphingolipids obtained from mammalian tissue on phagocytosis was also compared with that of bacterial glycosphingolipids. Ganglioside GM3 and sulfatide showed a marked stimulative activity for phagocytosis by PMN, while the neutral glycosphingolipids did not. Thus, bacterial acidic glycosphingolipid and mammalian acidic glycosphingolipid promote phagocytosis and phagosome-lysosome fusion by PMN.

Glycosphingolipids↗
PubMed1995

Sleep disturbance in elderly patients with cognitive impairment, decreased daily activity and periventricular white matter lesions.

We investigated how sleep disturbance is correlated with brain lesions, cognitive impairment and decreased daily activity (ADL). Two hundred and four chronically ill patients including patients with vascular dementia were classified into eight groups based on cognitive function, ADL and grades of PVL (periventricular lucency) as shown by computerized tomography. Visual monitoring of the sleep/wake state was performed hourly for 14 consecutive days and the daytime sleep hours and the nighttime sleep hours were determined based on detected disturbances in the sleep/wake pattern. Whether any specific infarcted regions were correlated with sleep disturbance was also evaluated. We found that daytime sleep hours were increased and nighttime sleep hours were decreased by three single factors: cognitive impairment, decreased ADL and the severe grade of PVL. As for an interactive effect of the two factors, daytime sleep hours were increased by dementia with decreased ADL (independent of PVL) and increased by decreased ADL with the severe grade of PVL (independent of dementia). Although three factors affected sleep independently, ADL has an interactive effect on sleep with dementia and with PVL. No specific cortical regions related to sleep disturbance were found.

Activities of Daily Living↗
PubMed1995

Identification of the location of antigenic sites of swine vesicular disease virus with neutralization-resistant mutants.

Neutralization sites on swine vesicular disease virus (SVDV) have been identified by sequence analysis of neutralization-resistant mutants. Eight neutralizing monoclonal antibodies (MAbs) were produced and neutralization-resistant mutants were selected with the MAbs. Resistance of the mutants to neutralization was shown using the stab-neutralization method, and the results indicated the presence of five neutralization sites on the virus. The location of each site was identified from amino acid changes resulting from nucleotide substitutions in the mutants, and designated site 1 (residues 87 and 88 of VP1), 2a (residue 163 of VP2), 2b (residue 154 of VP2), 3a (residue 272 and 275 of VP1, 60 of VP3) and 3b (residues 70 and 233 of VP2, 73 and 76 of VP3). The locations of the amino acids substitutions at each site formed a cluster on a computer-simulated three-dimensional model of SVDV and were exposed to the surface of the virion.

Amino Acids↗
PubMed1995

The inhibitory effect of kampou extracts on in vitro calcium oxalate crystallization and in vivo stone formation in an animal model.

Kampou medicine is a traditional Japanese therapeutic system which originated in China and was used to treat various diseases for hundreds of years until it was superseded by Western medicine. In recent years, there has been a resurgence of interest in Kampou medicine among many physicians. Unfortunately, however, little evaluation has been performed using objective scientific methods until now, and the pharmacodynamics of Kampou medicine are still unclear. Generally speaking, Kampou medicine has been shown to have fewer side-effects than Western medicine based on the experience gained from its long usage. We first selected 16 Kampou extracts for screening as possible calcium oxalate stone prophylactic agents in vitro. This resulted in the selection of two kinds of Kampou extracts, Takusya and Kagosou, as potential Kampou extracts for stone prophylaxis. Next, these two Kampou extracts were tested in vivo for their effects on stone formation in an animal model. Takusya showed significant stone prophylaxis, while Kagosou did not. Lastly, Chorei-to, which contains Takusya and has been approved for prescription as a Kampou medicine for urolithiasis patients in Japan, was examined in vivo at two different concentrations. As a result, a low dose of Chorei-to which corresponded to the human daily dose per unit of body weight exhibited apparent stone prophylaxis, despite the disadvantage of decreasing citrate excretion. In contrast, high doses of Chorei-to did not exhibit stone prophylaxis in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Anticonvulsant efficacy of ADCI (5-aminocarbonyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine) after acute and chronic dosing in mice.

ADCI (5-aminocarbonyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine), a low-affinity uncompetitive N-methyl-D-aspartate (NMDA) antagonist, is a broad-spectrum anticonvulsant with a favorable side-effect profile. In the present study, we sought to determine if tolerance develops to the anticonvulsant activity of ADCI, using the maximal electroshock (MES) test to assess seizure protection. Mice were treated with three daily injections of a 2 x ED50 dose for MES protection (18 mg/kg, intraperitoneally, i.p.) or vehicle for 7 or 14 days. On the day after the chronic treatment protocol, all animals received a challenge dose of ADCI (18 mg/kg) and 15 min later were evaluated in the MES test. In control animals, 83-94% of animals were protected and the ADCI plasma levels immediately after the MES test were 5.5-9.7 micrograms/ml. In treated animals, 29 and 0% of animals were protected at 7 and 14 days, respectively, and the ADCI plasma levels were 77 and 52% of the control values. [3H]Dizocilpine binding to brain NMDA receptors was unaltered by the chronic drug treatment. In subsequent experiments, we determined that 14-day chronically treated animals could be completely protected by increased doses of ADCI (ED50 28.9 mg/kg). In both naive and chronically treated animals receiving a challenge dose of ADCI, plasma drug levels decreased in two phases, the first with a time constant of approximately 55 min and the second with a much slower rate. The estimated plasma concentrations of ADCI reflecting threshold (3-5 micrograms/ml) and 50% protection (5-7.5 micrograms/mg) were similar in naive and chronic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Congenital hypopituitarism with hypoplasia of the anterior pituitary gland and a normal posterior pituitary lobe.

We report a female infant with congenital hypopituitarism. All anterior pituitary hormones were deficient, and the anterior pituitary gland was undetectable on magnetic resonance images. Antidiuretic hormone secretion was appropriate, and the posterior lobe was localized at the end of the stalk, in the sella. These observations suggest that the posterior pituitary gland may develop independently of the anterior lobe.

Female↗
PubMed1995

[Isolation of verotoxin-producing Escherichia coli from pediatric patients suffering from enteritis with bloody stool and intussusception].

We tried to isolate verotoxin-producing Escherichia coli (VTEC) on sorbitol-MacConkey (SMAC) agar and in part by the polymerase chain reaction (PCR) method from sporadic enteritis patients with bloody stools and intussusception patients who came to three pediatric clinics in the Fukuoka area from October 1990 to September 1994. VTEC O157:H7 strains were isolated from 6 (10.5%) of 57 patients with bloody stools, Campylobacter spp. 15 (26.3%), Salmonella spp. 14 (24.6%) and Yersinia enterocolitica 2. We were not able to detect VT genes by PCR from 11 of 20 patients from whose stools no causative bacteria were isolated. Massive fresh bloody stools following frequent watery diarrhea were typical of the VTEC enteritis patients. Only 1 patient had fever and 2 had leukocytosis, but the C-reactive protein in all of them was below 1+. The VTEC strains were isolated during the summer season, 1 in June, 2 in July, and 3 in September. Since in the area O157:H7 appeared to be the most prevalent VTEC serotype, SMAC is very useful for screening VTEC in bloody stools. VTEC seems to be a rare pathogen of intussusception because the organisms were detected from none of the 30 patients.

Adolescent↗
PubMed1995

Flagellar filament structure and cell motility of Salmonella typhimurium mutants lacking part of the outer domain of flagellin.

We have isolated spontaneous mutants of Salmonella typhimurium which can swim in the presence of antifilament antibodies. The molecular masses of flagellins isolated from these mutants were smaller than that (52 kDa) of wild-type flagellin. Two mutants which produced the smallest flagellins (42 and 41 kDa) were selected, and the domain structures of the flagellins were analyzed by trypsin digestion and then subjected to amino acid sequencing. The two flagellins have deletions at Ala-204 to Lys-292 and Thr-183 to Lys-279, respectively. These deleted parts belong to the outer domain (D3) of flagellin, which is believed to be at the surface of the filament. These mutant filaments aggregated side by side in the presence of salt, resulting in disordered motility.

Amino Acid Sequence↗
PubMed1995

Effect of some immunosuppressors on allergic bronchial inflammation and airway hyperresponsiveness in mice.

The effects of two new immunosuppressors, FK-506 and mizoribine, on antigen-induced bronchial inflammation and reactivity to acetylcholine in mice were studied in comparison with those of cyclosporin A and cyclophosphamide. Three inhalations of an antigen by actively sensitized BALB/c mice resulted in an increase in airway reactivity to acetylcholine. Twenty-four hours after the final inhalation, the number of leukocytes (mononuclear cells and eosinophils) and the amount of interleukin 5 (IL-5) increased significantly. In BALB/c nu/nu mice (athymic mice), three inhalations of antigen caused no significant change in either airway inflammation or hyperresponsiveness. The administration of each of the four immunosuppressors clearly inhibited antigen-induced airway eosinophilia. Moreover, FK-506, mizoribine and cyclophosphamide clearly inhibited the antigen-induced IL-5 production and cyclosporin A showed the tendency to inhibit IL-5 production. Whereas FK-506, mizoribine and cyclosporin A clearly inhibited the antigen-induced airway hyperreactivity in BALB/c mice, cyclophosphamide did not show a significant effect on this airway hyperreactivity. These results indicate that FK-506, mizoribine and cyclosporin A, but not cyclophosphamide, inhibit antigen-induced airway hyperreactivity in mice. The mechanism which inhibits antigen-induced airway eosinophilia and IL-5 production is not involved in the inhibitory mechanism of airway hyperreactivity by FK-506 and mizoribine.

Aerosols↗
PubMed1995

Adenosine A1 receptor mRNA in microdissected rat nephron segments.

Adenosine plays several roles in the kidney mediated by the specific receptors A1, A2, and possibly A3. We studied the localization of adenosine A1 receptor mRNA in rat nephron segments using reverse transcription and polymerase chain reaction (RT-PCR). The nephron segments of male Sprague-Dawley rats (6 to 8 weeks old) were microdissected. Total RNA was prepared by the acid-guanidinium-phenol-chloroform method and used in the following RT-PCR assay. Because the PCR primers spanned no intron, samples reacted in the absence of RT were used as controls for amplification of genomic DNA. The PCR products were size-fractionated by electrophoresis, visualized with ethidium bromide staining, and confirmed by Southern blot analysis. PCR products were detected in all of the nephron segments examined. No signals were detected in samples reacted in the absence of RT. Strong signals were detected in glomeruli, medullary collecting duct, cortical thick ascending limb, and medullary thick ascending limb, while weak signals were found in proximal convoluted and straight tubules. Previously, the presence of A1 receptors has been demonstrated in glomeruli, collecting duct, and thick ascending limb in the rat kidney by autoradiography and binding studies. In addition to these segments, we further detected A1 receptor mRNA in proximal convoluted and straight tubules. Thus, A1 receptor mRNA seems to be broadly expressed along the nephron.

Animals↗
PubMed1995

Purification of human very-long-chain acyl-coenzyme A dehydrogenase and characterization of its deficiency in seven patients.

Mitochondrial very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) was purified from human liver. The molecular masses of the native enzyme and the subunit were estimated to be 154 and 70 kD, respectively. The enzyme was found to catalyze the major part of mitochondrial palmitoylcoenzyme A dehydrogenation in liver, heart, skeletal muscle, and skin fibroblasts (89-97, 86-99, 96-99, and 78-87%, respectively). Skin fibroblasts from 26 patients suspected of having a disorder of mitochondrial beta-oxidation were analyzed for VLCAD protein using immunoblotting, and 7 of them contained undetectable or trace levels of the enzyme. The seven deficient fibroblast lines were characterized by measuring acyl-coenzyme A dehydrogenation activities, overall palmitic acid oxidation, and VLCAD protein synthesis using pulse-chase, further confirming the diagnosis of VLCAD deficiency. These results suggested the heterogenous nature of the mutations causing the deficiency in the seven patients. Clinically, all patients with VLCAD deficiency exhibited cardiac disease. At least four of them presented with hypertrophic cardiomyopathy. This frequency (> 57%) was much higher than that observed in patients with other disorders of mitochondrial long-chain fatty acid oxidation that may be accompanied by cardiac disease in infants.

Acyl Coenzyme A↗
PubMed1995

Stimulation by thyroid-stimulating hormone and Grave's immunoglobulin G of vascular endothelial growth factor mRNA expression in human thyroid follicles in vitro and flt mRNA expression in the rat thyroid in vivo.

To elucidate the pathogenesis of thyroid gland hypervascularity in patients with Graves' disease, we studied the expression of mRNAs for vascular endothelial growth factor (VEGF) and its receptor, Flt family, using human thyroid follicles in vitro and thiouracil-fed rats in vivo. Human thyroid follicles, cultured in the absence of endothelial cells, secreted de novo-synthesized thyroid hormone in response to thyroid-stimulating hormone (TSH) and Graves' IgG. The thyroid follicles produced VEGF mRNA but not flt-1 mRNA. The expression of VEGF mRNA was enhanced by insulin, tumor-promoting phorbol ester, calcium ionophore, dibutyryl cAMP, TSH, and Graves' IgG. When rats were fed thiouracil for 4 wk, their serum levels of TSH were increased at day 3. VEGF mRNA was also increased on day 3, accompanied by an increase in flt family (flt-1 and KDR/ flk-1) mRNA expression. These in vitro and in vivo findings suggest that VEGF is produced by thyroid follicles in response to stimulators of TSH receptors, via the protein kinase A and C pathways. VEGF, a secretable angiogenesis factor, subsequently stimulates Flt receptors on endothelial cells in a paracrine manner, leading to their proliferation and producing hypervascularity of the thyroid gland, as seen in patients with Graves' disease.

Animals↗
PubMed1995

Chemical constituents of Chinese natural medicine, morindae radix, the dried roots of morinda officinalis how.: structures of morindolide and morofficinaloside.

A new iridoid lactone, morindolide, and a new iridoid glucoside, morofficinaloside, have been isolated from a Chinese natural medicine, Morindae Radix, the dried root of Morinda officinalis How. together with a number of known compounds: five anthraquinones, four iridoid glucosides, a monoterpene glycoside, two sterols, an ursane-type triterpene, and a lactone compound. The chemical structures of the new compounds were determined on the basis of chemical and physicochemical evidence.

Acetylation↗
PubMed1995

Studies on anti-allergic action of AH 21-132, a novel isozyme-selective phosphodiesterase inhibitor in airways.

The effects of AH 21-132, a type III and IV phosphodiesterase (PDE) inhibitor, on allergic reactions in the airway were studied by comparing them with the effects of rolipram, a type IV PDE inhibitor, and aminophylline, a non-selective PDE inhibitor. The following results were obtained: 1) AH 21-132, rolipram and aminophylline inhibited the antigen-induced contraction of isolated guinea pig tracheal muscle in vitro. 2) AH 21-132 and aminophylline inhibited antigen-induced histamine release from human lung tissue fragments. 3) Antigen-induced accumulation of inflammatory cells including eosinophils and macrophages in mice bronchoalveolar lavage fluid was clearly inhibited by AH 21-132 and rolipram, but not by aminophylline. 4) AH 21-132, rolipram and aminophylline inhibited immediate phase bronchocostriction induced by either an intravenous or an aerosol challenge of antigen in guinea pigs. 5) AH 21-132 and rolipram inhibited the aeroantigen challenge-induced late phase increase in the airway resistance in guinea pigs, but aminophylline did not. These results suggest that AH 21-132 has an anti-allergic effect in the airway and that these actions may be beneficial for the treatment of allergic bronchial asthma.

Aminophylline↗