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Biomedical subjects

S Yamaguchi

Publications and source records attributed to S Yamaguchi.

At least 829 records · Page 46Linked to original sources
PubMed1991

[Hemodynamic and metabolic changes in crossed cerebellar hypoperfusion--similarity to the early stage of olivo-ponto-cerebellar atrophy].

Using positron emission tomography in twenty-four unilateral supratentorial stroke patients, we evaluated regional blood flow, metabolic rate of oxygen, oxygen extraction fraction, and blood volume in the cerebellar cortex and pons. Sixteen patients with a significant cerebellar blood flow asymmetry, which lay beyond the upper ninety-five percent confidence limits defined in eight normal subjects, were selected as the group with crossed cerebellar hypoperfusion. In these patients, cerebellar metabolic rate of oxygen was also significantly decreased in the cerebellar cortex contralateral to the supratentorial stroke, compared with the ipsilateral cerebellar cortex, although to a lesser degree than the cerebellar blood flow. The degrees of cerebellar asymmetry in these two parameters were negatively correlated with the metabolic rate of oxygen in the pons. Oxygen extraction fraction was slightly, but significantly, increased in the cerebellar cortex contralateral to the stroke. In contrast to the ischemic state, cerebellar blood volume was decreased, with no difference in the ratio of cerebellar blood flow to blood volume. These findings suggest 1) interruption of the cortico-ponto-cerebellar tract as the mechanism of crossed cerebellar hypoperfusion and 2) mild elevation in the oxygen extraction fraction in this state, with a mechanism distinct from primary hypoperfusion. We also studied six patients with sporadic olivo-ponto-cerebellar atrophy who were in the incipient stage of the disease with slight cerebellar atrophy on magnetic resonance images. The cerebellar cortex in these patients showed the same hemodynamic and metabolic changes as in crossed cerebellar hypoperfusion, suggesting the cerebellar metabolic depression by transneuronal mechanism in the early stage of olivo-ponto-cerebellar atrophy.

Adult↗
PubMed1991

Enzymatic synthesis of novel oligosaccharides by use of transglycosylation activity of endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae.

The transglycosylation activity of endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae was used for the enzymatic synthesis of novel oligosaccharides. When (Man)6(GlcNAc)2Asn was used as a substrate for the transglycosylation, (Man)6GlcNAc-Glc, (Man)6GlcNAc-Man, (Man)6GlcNAc-chitobiose, and (Man)6GlcNAc-gentiobiose were synthesized. Their structures were identified by HPLC, ion spray mass spectrometry, and digestion with glycosidases. Endo-beta-N-acetylglucosaminidases hydrolyzed the pyridylamino derivatives of these oligosaccharides.

Arthrobacter↗
PubMed1991

Electroretinogram in cone dystrophy.

Electroretinograms (ERGs) in 10 cases of cone dystrophy were studied with special respect to log(bp/bs) that represents the log of photopic ERG amplitude divided by scotopic ERG amplitude. Photopic ERGs were either greatly diminished or nonrecordable, and scotopic ERGs showed either normal or reduced amplitudes. All cases had a low value of log(bp/bs), less than the lower normal limit, indicating significantly greater impairment in cone function than in rod function. These results have proved log(bp/bs) to be helpful in confirming the diagnosis of cone dystrophy especially in cases with recordable photopic ERG and reduced scotopic ERG. Among other ERG parameters, the photopic ERG b-wave implicit time that was determined with averaging and digital amplification of the responses in 4 cases showed prolongation in 3 cases while normal in one case. Oscillatory potentials were nonrecordable or barely recordable in all cases.

Adult↗
PubMed1991

[Effects and complications of continuous hepatic arterial infusion chemotherapy using implantable reservoir for liver metastases from colorectal cancer].

Continuous arterial infusion chemotherapy using implantable reservoir was performed for unresectable liver metastases from colorectal cancer and the therapeutic effects, side effects and complications were evaluated. Eleven patients were treated with four kinds of arterial infusion courses that mainly consisted of 5-FU. The arterial infusion courses were discontinued in 2 patients because of nausea and vomiting, and in one patient because of diarrhea. The catheters were dislocated in 2 patients and another 2 developed fistulous between the hepatic artery and bile duct. Three patients developed duodenal ulcer. Serum CEA was reduced in 4 patients (36%). After all, response rate was 9% (1/11). The one-year survival rates of all cases and cases treated with more than 4 courses were 36.3% and 80.0%, respectively.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Anticonvulsant activity of the low-affinity uncompetitive N-methyl-D- aspartate antagonist (+-)-5-aminocarbonyl-10,11-dihydro-5H- dibenzo[a,d]cyclohepten-5,10-imine (ADCI): comparison with the structural analogs dizocilpine (MK-801) and carbamazepine.

(+-)-5-Aminocarbonyl-10,11-dihydro-5H-dibenzo[a,d] [a,d]cyclohepten-5,10-imine (ADCI), a tricyclic compound structurally related to dizocilpine (MK-801) and carbamazepine, was a potent anticonvulsant in the mouse maximal electroshock seizure test when administered i.p. (ED50, 8.9 mg/kg) or p.o. (ED50, 23.5 mg/kg), but failed to cause motor impairment except at substantially higher doses (TD50 values, 49.2 mg/kg i.p. and 293 mg/kg p.o.). ADCI was also protective against chemically induced seizures in mice, including those produced by 4-aminopyridine (ED50, 7.1 mg/kg s.c.) and pentylenetetrazol (ED50, 37.4 mg/kg s.c.). In addition, ADCI antagonized the behavioral effects and lethality of s.c. administered N-methyl-D-aspartate (NMDA: ED50, 15.2 mg/kg), but was a weaker antagonist of kainate-induced clonic seizures (ED50, 33.0 mg/kg), indicating that the drug is a selective functional NMDA antagonist. In common with other NMDA antagonists, ADCI retarded the development of amygdaloid kindled seizures in rats, but failed to attenuate the afterdischarge duration in fully kindled animals. Whole cell voltage clamp recordings from cultured hippocampal neurons demonstrated that ADCI selectively blocks inward current responses to NMDA in a use-dependent fashion without affecting responses to kainate or quisqualate, indicating that ADCI is a selective open channel (uncompetitive) blocker of the NMDA receptor-ionophore complex. ADCI blocked NMDA-evoked inward current responses with a potency (IC50, 14 microM) similar to that with which it displaces [3H]-1-[1-(2-thienyl)-cyclohexyl]piperidine from binding to NMDA receptor channels in rat brain homogenates (IC50, 11.3 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

Anterior and posterior association cortex contributions to the somatosensory P300.

A P300 (P3)-evoked response is generated in a variety of mammalian species upon detection of significant environmental events. The P3 component has been proposed to index a neural system involved in attention and memory capacity. We investigated the contribution of anterior and posterior association cortex to somatosensory P3 generation. Somatosensory event-related potentials (ERPs) were recorded in controls (n = 10) and patients with unilateral lesions in temporal-parietal junction (n = 8), lateral parietal cortex (n = 8), or dorsolateral frontal cortex (n = 10). Subjects pressed a button to mechanical taps of the fifth finger (targets; p = 0.12), randomly interposed in sequences of taps to the second (standards; p = 0.76) and the third or fourth finger (tactile novels; p = 0.06). Occasional shock stimuli were delivered to the wrist (shock novels; p = 0.06). The scalp-recorded P3 was differentially affected by anterior and posterior association cortex lesions. Subjects with temporal-parietal lesions showed markedly reduced P3s to all types of stimuli at all scalp locations. The reductions were largest at the parietal electrode site over the lesioned hemisphere. Parietal patients had normal P3s for all stimulus types except for contralateral shock novels, which generated reduced P3s. Frontal lesions had reductions of the novelty P3 over frontal sites with minimal changes in the target P3. The data support the existence of multiple intracranial P3 sources. The data further indicate that association cortex in the temporal-parietal junction is critical for generating the scalp-recorded target and novelty P3s, whereas dorsolateral frontal cortex contributes preferentially to novelty P3 generation. The N2 component was reduced by parietal and frontal lesions in patients who had intact target P3s, suggesting that different neural systems underlie N2 and P3 generation.

Aged↗
PubMed1990

Effects of bile acids on development of pepsinogen-altered pyloric glands in rats.

The effects of dietary bile acids on the development of pepsinogenaltered pyloric glands (PAPG) were examined. Male WKY/NCrj rats were given a single dose of 160 mg/kg body wt. of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) by gastric intubation and fed basal diet containing 0.3% sodium taurocholate (Na-TC), 0.3% sodium cholate (Na-C), 0.3% sodium glycocholate (Na-GC), 0.3% sodium tauroglycocholate, 0.3% sodium deoxycholate, 0.1% chenodeoxycholic acid or 0.5% lithocholic acid for 14 weeks. All rats also received 1 ml of saturated NaCl solution 4 times by i.g. intubation. At the end of week 16, the animals were killed, and the number of PAPG per cm of mucosal length was determined immunohistochemically. Na-TC, Na-C and Na-GC significantly increased the number of PAPG over the control value, suggesting that they may have activity to promote gastric carcinogenesis.

Animals↗
PubMed1990

Effects of naturally occurring antioxidants on combined 1,2-dimethylhydrazine- and 1-methyl-1-nitrosourea-initiated carcinogenesis in F344 male rats.

The effects of treatment with naturally occurring antioxidants, selenium, beta-carotene, ferulic acid, esculin and eugenol during the promotional phase of tumor development were investigated in male F344 rats pre-treated with 1,2-dimethylhydrazine (DMH) and 1-methyl-1-nitrosourea (MNU). Animals were given 3 subcutaneous injections of DMH at a dose of 40 mg/kg body wt. within 1 week and then were injected with MNU i.p. at a dose of 20 mg/kg body wt. 2 times per week, for 2 weeks. Thereafter, the rats were maintained on diet containing either 0.2% beta-carotene, 2 ppm selenium, 1% ferulic acid, 1% esculin or 0.8% eugenol. At week 52, surviving rats were killed and complete histological examinations were performed. Administration of eugenol enhanced the development of both hyperplasia and papillomas in the forestomach. Although treatment with beta-carotene tended to decrease the incidence and number of large intestinal carcinomas, beta-carotene, selenium, esculin and eugenol all decreased the incidence of kidney nephroblastomas, the differences were not statistically significant. The results thus showed that eugenol exerts promoting activity for forestomach carcinogenesis while the other antioxidants might have weak organ-specific inhibitory effects under these experimental conditions.

1,2-Dimethylhydrazine↗
PubMed1990

Gating of somatosensory input by human prefrontal cortex.

Somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded in controls and in patients with focal lesions in dorsolateral prefrontal cortex (PFCx). Unilateral PFCx lesions increased the amplitude of the P26 component generated in postcentral areas 1 and 2. The amplitudes of the N28, P45 and N67 SEP components recorded over post-rolandic and frontal electrodes were also enhanced by PFCx damage. In contrast, the N19 component generated in postcentral area 3b was unaffected by PFCx lesions. The results indicate that PFCx exerts inhibitory modulation on sensory processing that may be mediated by corticocortical PFCx-parietal connections.

Aged↗
PubMed1990

[An overview of breast cancer mass screening in Japan].

To establish the effective mass screening projects for the breast cancer, our study group cosponsered by the Welfare Ministry was organized by 11 regional groups. From 1968 to 1986, 643, 513 women at the initial screening and 719, 189 women at the subsequent screening were examined by physical examination. Out of them, abnormalities were present in 24, 864 women (3.9%) and 23,880 (3.3%), respectively. A detection of cancer was made in 833 women (detection rate 1.3%) and 428 women (0.6%), respectively. As the examinees increased from year to year, the subsequent examinees were over the initial ones. It was suggested that most of examinees had been fixed year by year and the detection rate of initial screening had been higher than that of the subsequent one. Then more initial examinees are expected to be increased. Women 30 to 59 years of age were mostly screened, but women aged 60 or more should be increased. Of women with abnormal physical findings, women over 90% took the second examination. But more effective, economical and safer screening instruments are expected to be developed and be used at the first examination.

Adult↗
PubMed1990

Urinary crystal surface binding substances on calcium oxalate crystals.

In order to study the effect of urinary crystal surface binding substances (CSBS), we extracted the naturally existing CSBS from urine from healthy individuals by conducting homogeneous crystallization of calcium oxalate. CSBS proved not to be promoters but rather strong inhibitors of calcium oxalate crystal growth and aggregation. It is suggested that CSBS exhibited their inhibitory effect by masking the growing sites and aggregating sites on the crystal surface. As for the characteristics of CSBS, we found around 10 peaks of molecular weight, and all of them contained both peptides and saccharides. The findings suggest that CSBS are composed of various kinds of glycoproteins and proteoglycans.

Adult↗
PubMed1990

Gene deletions in Japanese patients with Duchenne and Becker muscular dystrophy.

Thirty-eight unrelated Japanese patients with Duchenne and Becker muscular dystrophy (DMD and BMD) have been investigated with the DMD cDNA probes. The 14-kb DMD cDNA was subdivided into 6 subclones and HindIII-digested DNAs were analyzed by Southern blotting. Out of 38 unrelated patients, 14 showed a deletion of one or several of the exon-containing HindIII fragments (36.8%). These corresponded to 50% (9/18) of BMD patients and 25% (5/20) of DMD patients, and the position and extent of deletions were mapped and proved to be more heterogeneous in DMD than in BMD. Both ends of deletions detected in probe 1-2a were common to all six BMD patients without the maintenance of reading frame of messenger RNA, and 5' ends of deletions in probe 5b-7 were also common but maintained in frame in three BMD patients. The phenotypic-specific deletion in Japanese BMD patients has existed in the 5' end of the DMD gene, although its apparently similar deletion produced a wide range of clinical courses (BMD phenotype). There was no tight correlation between clinical severity and presence or absence of deletion in DMD or BMD.

Adolescent↗
PubMed1990

Segmental diastolic narrowing of epicardial coronary arteries in aortic regurgitation. Phase analysis by quantitative angiography of coronary artery diameter change during cardiac cycles.

A new finding of a segmental narrowing of the left anterior descending coronary artery in diastole (diastolic narrowing: DN) was reported. DN was found in 6 out of 45 patients (13.3%, 5 males, 1 female) with chronic aortic regurgitation (AR). It is likely that aortic regurgitation was more severe in terms of the history of heart failure, regurgitant fraction, left ventricular end-diastolic volume index and pressure, and aortic diastolic pressure in the patients with DN compared with those without DN. The phasic change of DN in cardiac cycles was analyzed by quantitative angiography, and indicated that DN commences at a point in mid-diastole when coronary vascular driving pressure (the instantaneous aortic and LV pressure difference) becomes abnormally reduced, reaches its maximum at end-diastole, and gradually recovers as aortic pressure increases during systole. In two patients, DN was no longer evident after valve replacement. We concluded that DN, a new coronary arteriographic finding, reflects the integrated severity of AR.

Angina Pectoris↗
PubMed1990

Signet ring cell early gastric cancer presenting as an elevated lesion.

Early gastric cancer composed of signet ring cell carcinoma is usually present as a depressed lesion and rarely manifests as a protruding lesion. To our knowledge, only eight cases have been reported in the literature. We herein report such a rare lesion which developed in an asymptomatic 55-year-old man.

Adenocarcinoma, Mucinous↗
PubMed1990

Synthesis and anticonvulsant activity of 1-phenylcyclohexylamine analogues.

Thirty-eight analogues of 1-phenylcyclohexylamine (PCA), a phencyclidine (PCP) derivative, were examined for their activities in the mouse maximal electroshock (MES) seizure test and in a motor-toxicity assay. In addition, we determined the binding affinities of the compounds for PCP acceptor sites in rat brain membranes labeled with [3H]-1-[1-(2-thienyl)cyclohexyl]piperidine. Many of the analogues were protective against MES seizures (ED50s of 5-41 mg/kg, ip) and all of these compounds caused motor toxicity. The potencies in the motor toxicity and MES seizure tests showed a moderate correlation with the affinities for PCP sites. Several analogues exhibited a greater separation of potencies in the motor toxicity and MES seizure tests than did the parent compound PCA. These were obtained by (i) 3-methylation of the cyclohexyl ring trans to the phenyl ring, (ii) methoxylation at the ortho position on the phenyl ring, and (iii) contraction of the cyclohexane ring to form the corresponding cyclopentane.

Animals↗
PubMed1990

Comparison of initiation potential of 2-amino-3-methylimidazo[4,5-f]quinoline and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline in an in vivo carcinogen bioassay system.

A new approach to low-dose assessment of carcinogenic potential was applied to food contaminant pyrolysis products. Single intragastric doses of the carcinogenic pyrolysates, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) or 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline MeIQx), were given 12 h after two-thirds partial hepatectomy (PH) to F344 male rats. Two weeks thereafter the animals were placed on a basal diet containing 0.05% phenobarbital (PB) for 6 weeks combined with an i.p. administration of D-galactosamine (300 mg/kg) to facilitate growth of initiated cells. Both IQ and MeIQx clearly caused initiation of hepatocarcinogenesis as revealed by induction of preneoplastic placental-form glutathione-S-transferase-positive (GST-P+) hepatocyte foci composed of more than three cells (approximately 30 microns in diameter). A similar protocol without performance of PH before pyrolysate administration gave a positive result only for the IQ-treated group indicating that cell proliferation is essential during the low-dose, one-shot initiation step. IQ was found to be two to three times more potent in inducing GST-P+ foci using both protocols. The current approach could find application in practical carcinogenicity screening of chemicals, for which only small amounts are available.

Animals↗