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Biomedical subjects

S Yamaguchi

Publications and source records attributed to S Yamaguchi.

At least 577 records · Page 32Linked to original sources
PubMed1995

Identification of the D-enantiomer of 2-hydroxyglutaric acid in glutaric aciduria type II.

We determined the optical isomer of the 2-hydroxyglutaric acid (2HG) that was elevated in the urine of five Japanese children with a mild form of glutaric aciduria type II (GA2), caused by a deficiency of electron transfer flavoprotein (ETF) or ETF-ubiquinone oxidoreductase (ETF-QO). The D- and L-enantiomers of 2HG were separated by capillary gas chromatography with a combination of (S)-(+)-2-octanol derivatization and chromatography on a DB-1 column. The isomer that was elevated in GA2 patients was predominantly the D-enantiomer, an observation that may serve as an additional marker for the biochemical diagnosis of GA2. D-2HG dehydrogenation, but not L-2HG dehydrogenation is apparently blocked in GA2. A specific D-2HG dehydrogenase or D-2HG-CoA dehydrogenase may be metabolically linked to ETF and ETF-QO in the mitochondria.

Biomarkers↗
PubMed1995

Synthesis of neoglycoproteins using oligosaccharide-transfer activity with endo-beta-N-acetylglucosaminidase.

We describe a novel method for the enzymatic synthesis of neoglycoproteins. Endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (Endo-A) had high levels of transglycosylation activity. The enzyme activity of Endo-A was markedly increased by adding 4-L-aspartyl-glycosylamine (GlcNAc-Asn) to the reaction mixture. Digesting (Man)6(GlcNAc)2 with the enzyme in the presence of GlcNAc-Asn gave a mixture of hydrolytic ((Man)6GlcNAc) and transglycosylic ((Man)6(GlcNAc)2-Asn) products. By means of transglycosylation, (Man)6GlcNAc was transferred en bloc to the partially deglycosylated ovalbumin glycopeptide (EEKYN(GlcNAc)LTSVL) concomitant with the hydrolysis of (Man)6-GlcNAc)2Asn. The structure of the transglycosylation product was designated as (Man)6(GlcNAc)2-peptide by amino acid composition and sequence analysis as well as ion mass spectrometry. The enzyme also transferred oligosaccharide to partially deglycosylated ribonuclease B (GlcNAc-protein) during the hydrolysis of (Man)6-(GlcNAc)2Asn. Native ribonuclease B had (Man)5-9 (GlcNAc)2 as its heterogeneous N-linked sugar chains. High performance liquid chromatography showed that all of the N-linked sugar chains of the synthetic neoribonuclease of the pyridylamino derivatives were modified to (Man)6(GlcNAc)2.

Amino Acid Sequence↗
PubMed1995

Molecular variant of angiotensinogen gene is associated with coronary atherosclerosis.

BACKGROUND: A positive association was previously reported between angiotensin-converting enzyme (ACE) gene polymorphism and several cardiovascular diseases, such as myocardial infarction, left ventricular hypertrophy, and restenosis after percutaneous transluminal coronary angioplasty. Plasma ACE activity and carotid-wall thickening measured by ultrasonography were related, and it was postulated that long-term exposure to high levels of plasma ACE could be involved in structural changes of the arterial wall. In addition, angiotensinogen gene mutation was recently reported to be associated with essential hypertension and preeclampsia. There exists a possibility that the renin-angiotensin system plays an important role in the progress of cardiovascular diseases in humans. Therefore, we examined the association between the molecular variant of the angiotensin gene and coronary atherosclerosis. METHODS AND RESULTS: This study included 82 patients who had coronary atherosclerosis and 160 control subjects; all study participants were Japanese. All patients with coronary atherosclerosis had at least one coronary artery with > 25% luminal diameter obstruction on average according to multiple coronary angiographic views. Angiotensinogen gene molecular variants were designated AA, Aa, and aa. The a allele indicated thymine-cytosine transition at nucleotide 704 in exon 2. Genomic DNA was extracted from peripheral blood leukocytes. Polymerase chain reaction was performed to amplify the concerned region of the angiotensinogen gene. After restriction enzyme digestion, it was possible to distinguish the molecular variant of the angiotensinogen gene. The frequencies of these genotypes were 7.3%, 26.8%, and 65.9% in the patients and 18.8%, 31.9%, and 49.3% in the control subjects for the AA, Aa, and aa alleles, respectively. There was an excess in the a allele among patients (P < .01). CONCLUSIONS: We found a significant association between coronary atherosclerosis and a molecular variant of the angiotensin gene. The results suggested that the molecular variant of the angiotensinogen gene could be a new risk factor for coronary atherosclerosis.

Angiotensinogen↗
PubMed1995

A unique signal transduction from FLT tyrosine kinase, a receptor for vascular endothelial growth factor VEGF.

Flt-1 (fms-like tyrosine kinase-1), a receptor-type tyrosine kinase of sharing similar features with two other flt-family encoded proteins KDR/Flk-1 and Flt-4, has been recently identified as a receptor for Vascular Endothelial Growth Factor (VEGF) known to induce the proliferation of vascular endothelial cells. In this study, we demonstrate that Flt-1 encodes for a 180 kDa glycoprotein, binds VEGF with high affinity, undergoes autophosphorylation but does not generate any mitogenic response in transfected NIH3T3 fibroblasts. Interestingly, the immediate early gene c-myc was not induced, whereas the c-fos was induced very weakly in Flt-1 expressing NIH3T3 cells. A comparative analysis of the Flt-1 signal cascade in the environment of endothelial cells with that of Flt-1 expressing NIH3T3 cells showed that VEGF induced phosphorylation of PLC gamma and GAP complex on tyrosine in both type of cells. However, a strong activation of MAP kinases was observed only in endothelial cells. Further, different from many other receptor tyrosine kinases, tyrosine phosphorylation of Shc protein, an important adaptor for signal transduction from many receptor kinases, was very weak in both Flt-1-NIH3T3 cells and endothelial cells. These results suggest that Flt-1 kinase utilizes a unique signal transduction system in endothelial cells, and the activation of the Flt-1 kinase is insufficient to trigger a mitogenic response in NIH3T3 fibroblasts.

3T3 Cells↗
PubMed1995

Molecular, biochemical, and clinical characterization of mitochondrial acetoacetyl-coenzyme A thiolase deficiency in two further patients.

The molecular basis of mitochondrial acetoacetyl-CoA thiolase (T2) deficiency was studied in two patients (GK11 and GK16). Fibroblasts from each patient had detectable immunoreactive T2 polypeptide (CRM). In pulse-chase experiments, fibroblasts from GK11 had two types of CRM: one (type I CRM) disappeared after a 24-hr chase and migrated more slowly than that of the normal control; the other (type II CRM) was detected with a small amount even after a 72-hr chase and had normal electrophoretic mobility. GK16's fibroblasts had a CRM (type III) which was also detectable even after a 72-hr chase and showed a slower mobility than type I CRM. By analyzing amplified cDNA and genomic fragments, we showed that both patients are genetic compounds; GK11 for the mutations N158D and T297M, and GK16 for the mutations A301P and IVS8 (+1). Expression analyses confirmed that mutant T2 subunits with N158D, T297M, and A301P correspond to type I, II, and III CRM, respectively. Among them, only the mutant T2 polypeptide with T297M appeared to have a detectable residual activity, in spite of its instability. Cotransfection of two cDNAs containing N158D and T297M suggested that heterotetramer formation reduces residual activity in GK11 cells.

Acetyl-CoA C-Acetyltransferase↗
PubMed1995

Molecular basis of beta-ketothiolase deficiency: mutations and polymorphisms in the human mitochondrial acetoacetyl-coenzyme A thiolase gene.

beta-Ketothiolase deficiency is a deficiency in mitochondrial acetoacetyl-CoA thiolase (T2). We present here an update on mutations and polymorphisms in the human T2 gene. No large deletion or insertion has been observed in Southern blot analysis. Seventeen mutations were identified in 13 T2-deficient patients: nine missense, one nonsense, and five splice-site mutations, and two small deletions. Two polymorphic base substitutions were also detected. A common mutation in T2 deficiency has not been detected but 4 mutations (N158D, Q272X, 828 + 1, 1163 + 2) were identified in two independent families. Eleven of 25 mutant alleles identified caused aberrant splicing. In vivo expression analysis of 13 mutant cDNAs using a Lipofectin reagent suggested that T297M, A301P, A380T mutant alleles retain 5-10% normal T2 activity. A correlation between clinical phenotype and genotype in T2 deficiency seems unlikely.

Acetyl-CoA C-Acetyltransferase↗
PubMed1995

Prenatal diagnosis in a family with mitochondrial acetoacetyl-coenzyme A thiolase deficiency with the use of the polymerase chain reaction followed by the heteroduplex detection method.

Mitochondrial acetoacetyl-coenzyme A (CoA) thiolase deficiency is an organic aciduria which affects isoleucine and ketone body catabolism. GK16 (the index patient) was affected with this disorder and previous studies had revealed that GK16 was a compound heterozygote with IVS8(+1) gt to tt and A301P mutations. In a subsequent pregnancy, prenatal diagnosis was performed and the fetus's amniocytes were analysed by the polymerase chain reaction (PCR) followed by the heteroduplex detection method on a Mutation Detection Enhancement gel. The fetus was identified as a carrier of the IVS8(+1) mutation. We confirmed the diagnosis by immunoblot analysis of extracted amniocytes and gene analysis with blood filter paper after delivery. This is the first report of prenatal diagnosis of this disorder at the gene level.

Acetyl-CoA C-Acetyltransferase↗
PubMed1995

Alpha fetoprotein-producing acinar cell carcinoma of the pancreas showing multiple lines of differentiation.

An alpha fetoprotein (AFP)-producing tumour occurring in the head of the pancreas of a 30-year-old woman is reported. Histological examination revealed a markedly solid proliferation of tumour cells with prominent nucleoli and occasional luminal structures, some of which contained mucinous material stained with mucicarmine and alcian blue. No squamoid corpuscles were recognized. Immunohistochemistry showed intense positivity for lipase trypsin, and AFP basically, and single cells were also positive for carcino-embryonic antigen, CA19-9, synaptophysin and neuron-specific enolase. Pancreatic hormone-positive cells were absent. Electron microscopical examination revealed numerous granules of variable sizes in the tumour cells, which were considered to be zymogen. The tumour is an acinar cell carcinoma with multi-directional differentiation including the ability to produce AFP. Among AFP-positive pancreatic tumours, acinar cell carcinoma and pancreatoblastoma seem to be the most frequent.

Adult↗
PubMed1995

Detection of equine arteritis virus (EAV) by polymerase chain reaction (PCR) and differentiation of EAV strains by restriction enzyme analysis of PCR products.

A polymerase chain reaction (PCR) based assay capable of detecting and differentiating seven strains of equine arteritis virus (EAV) from around the world was developed. The primers for the PCR were chosen from the ORF6 gene encoding the unglycosylated membrane protein (M). Viral RNA from cell culture fluids infected with each of the seven EAV strains and RNA from the live vaccine, Arvac, was detected by PCR using four sets of primers. The sensitivity of detection was increased from 100 to 1,000 times by performing nested PCR enabling the detection of RNA at a level of 0.5-5 PFU. Differentiation among the virus strains and the live vaccine was achieved by cutting the PCR-amplified products from three sets of primers with six restriction endonucleases. Using this procedure it was possible to distinguish among the seven EAV strains used.

Base Sequence↗
PubMed1995

Axial movements of rat mandibular incisors measured under artificial respiration with halothane anaesthesia.

The axial movements of rat incisors were recorded continuously for over 20 h. The rats were anaesthetized with halothane delivered by intratracheal intubation using an artificial respirator. A haemostatic clamp was used to immobilize the jaw and the displacement detector exhibited high resolution, good linearity and low drift. The previously impeded and unimpeded eruption rates (the average extrusive movements) were 406 and 548 microns/24 h, respectively. The previously unimpeded rate was lower than the normal unimpeded rates obtained by other investigators. It appears that the eruptive movement of the previously unimpeded incisor was inhibited by halothane anaesthesia. Circadian rhythm was not observed in the eruption rates of previously impeded or unimpeded incisors. Following the i.p. injection of a lethal dose of pentobarbital sodium, the incisors retracted. The average intrusive movement was significantly greater in the previously impeded group (29 microns) than in the previously unimpeded group (12 microns) at 30 min after the lethal injection. It is assumed that the elimination of the pushing force at death may cause the stretched periodontal fibres to recoil, thereby pulling the tooth in an intrusive direction. It is also likely that the mechanical strength of the ligament is reduced in the previously unimpeded group by repeated shortening of the incisors; therefore the force needed to retract previously unimpeded incisors may be less than that needed to retract previously impeded incisors.

Animals↗
PubMed1995

Electrophysiologic correlates of visuo-spatial attention shift.

We investigated neurophysiologic correlates of shifting visual attention across the visual field. Event-related potentials (ERPs) were recorded in 12 normal subjects during a visual discrimination task in which target stimuli were presented at a predictable or unpredictable location in the eccentric visual field. Subjects were obliged to shift their attention from the expected site to the unpredictable site immediately after the presentation of shifted stimuli in order to detect the change of stimulus attributes. Shifted stimuli modulated the N1 component (130-200 msec), producing a larger amplitude at the posterior temporal site contralateral to the stimulus field and a smaller amplitude over the ipsilateral hemisphere. Furthermore, shifted stimuli uniquely evoked a positive ERP component with a latency of 200-300 msec, which distributed broadly over the skull maximally at the frontal and central electrode sites. Both the negative and positive components changed in amplitude as a function of shift distance and direction. These results suggest that modulations of the negative and positive deflections reflect the shift of covert visuo-spatial attention and that right hemispheric dominance does not exist at least in the early stage of shifting spatial attention.

Adult↗
PubMed1995

Low intensity areas observed on T2-weighted magnetic resonance imaging of the cerebral cortex in various neurological diseases.

The cerebral cortex of patients with Alzheimer's disease (AD) or amyotrophic lateral sclerosis (ALS) may show low signal intensity on T2-weighted magnetic resonance images (MRI). Since these low intensity areas (LIA) are also often observed in aged patients with other diseases, we suspected that they might be a non-specific finding. We conducted a retrospective study of LIA in 139 patients with various diseases of the central and peripheral nervous systems, and evaluated their relationship to age and other MRI findings. Brain atrophy, ventricular dilatation, white matter lesions, and LIA were visually evaluated on axial images of the spin echo sequences obtained with a 1.5 tesla (T) system. We found that LIA appeared after age 50 and became more common with advancing age. Their presence correlated with brain atrophy and white matter lesions. They were most frequent in the motor cortex, followed by the occipital and sensory cortices. Their incidence in the motor cortex was significantly higher in patients with central nervous system diseases than in those with peripheral neuropathy. We conclude that LIA are common in old patients with various neurological diseases and suggest that the deposition of iron in the cerebral cortices causes their development.

Adolescent↗
PubMed1995

The effect of a thromboxane A2 receptor antagonist BAY-u-3405 on experimental allergic reactions.

The effect of a novel thromboxane A2 receptor antagonist, BAY-u-3405, on experimental allergic airway and skin reactions was studied in vivo. At doses of 3-30 mg/kg BAY-u-3405 clearly inhibited the U-46619-induced increase in respiratory resistance (Rrs) in guinea pigs. BAY-u-3405 at doses of 3 and 30 mg/kg inhibited the aerosolized antigen-induced biphasic increase in respiratory resistance in guinea pigs. Moreover, BAY-u-3405 inhibited repeated aeroantigen-induced airway hyperactivity and airway inflammation in mice. In IgE antibody-mediated biphasic skin reactions in mice, both immediate and late-phase reactions were inhibited by 10 mg/kg of BAY-u-3405. These results demonstrate the efficacy of BAY-u-3405 on the antigen-induced late-phase reactions in the airway and skin in guinea pigs and mice, and antigen-induced airway hyperactivity in mice.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1995

Detection of measles virus genome directly from clinical samples by reverse transcriptase-polymerase chain reaction and genetic variability.

A simple and sensitive method for the detection of measles virus genome was developed, amplifying the regions encoding the nucleocapsid (N) protein and hemagglutinin (H) protein of measles virus by reverse transcriptase-polymerase chain reaction (RT-PCR). We examined a variety of measles patients: 28 patients with natural infection, 4 with measles encephalitis and 1 with subacute sclerosing panencephalitis (SSPE). In 28 patients with natural measles infection a single step PCR amplifying the N region resulted in a high detection rate for all plasma samples (28/28) within 3 days of the onset of rash and 80% (20/25) even on day 7 of the onset of rash and later. Within 3 days of the onset of rash, 24/25 (96.0%) of nasopharyngeal secretions (NPS) and 27/28 (96.4%) of peripheral blood mononuclear cells (PBMC) were positive for the N region PCR and the positivity rate of PCR decreased in NPS and PBMC after 7 days of the rash. In acute measles infection, measles genome was detected in all cell fractions, CD4, CD8, B cells, and monocytes/macrophages by the H gene nested PCR. Measles genome was also detected from cerebrospinal fluids (CSF) in patients with measles encephalitis, SSPE, and acute measles by the H gene nested PCR. PCR products of the N and H regions were sequenced and we confirmed the presence of measles genome. Based on the sequence data, chronological sequence differences were observed over the past 10 years. The sequences obtained from the SSPE patient were closely related to those of the wild viruses that were circulating at the time when the patient initially acquired measles. RT-PCR for NPS, PBMC, CSF, and plasma provides a useful method for the diagnosis of measles and molecular epidemiological study in addition to virus isolation.

Adolescent↗
PubMed1995

Angiotensin I converting enzyme (ACE) gene polymorphism and essential hypertension in Japan. Ethnic difference of ACE genotype.

A polymorphism of the angiotensin I converting enzyme (ACE) gene has recently been reported and analysis of this polymorphism has indicated that it is associated with several cardiovascular diseases. However, the results are still controversial and such association has not yet been established conclusively. To determine whether the ACE gene may be responsible for essential hypertension in a Japanese population, we also compared the distribution of genotypes and the allele frequency of this polymorphism in our findings of a Japanese population with these features in other countries. Eighty-seven hypertensive patients with a family history of essential hypertension and 95 normotensive patients whose parents had no such history were enrolled in the study. Polymorphism of the ACE gene was determined by using the polymerase chain reaction. Homozygotes for this polymorphism had either a 490-bp band (II) or a 190-bp band (DD) and heterozygotes had both bands (ID). In hypertensive subjects, the numbers and frequency of the ACE genotypes were: II, 44 (0.51); ID, 26 (0.30); DD, 17 (0.19). In normotensive subjects these were: II, 35 (0.37); ID, 43 (0.45); DD, 17 (0.18). There were no significant differences between the two groups in derived allele frequencies (chi 2 = 1.41). The difference between the overall allelic frequency in Japan and that reported in several other countries was significant. We did not find any association between ACE gene polymorphism and essential hypertension in Japan. However, there were significant differences in derived allele frequencies between our findings in a Japanese population and those reported from Europe and Australia.

Alleles↗