Biomedical subjects

S Yamaguchi

Publications and source records attributed to S Yamaguchi.

At least 343 records · Page 19Linked to original sources

PubMed1999

[Anesthetic management for transtracheal placement of a catheter for intracavity infusion of an antifungal drug in patients with pulmonary fungus ball of aspergillosis].

A catheter was inserted through the cricothyroid membrane under general anesthesia using a laryngeal mask airway in two patients with pulmonary fungus ball of aspergillosis to administer an antimycotic into the fungus ball. Anesthesia was induced with fentanyl and propofol in both patients. The laryngeal mask airway was inserted using intravenous injection of vecuronium. Anesthesia was maintained with continuous infusion of propofol. The catheter was inserted through the cricothyroid membrane and placed in the pulmonary fungus ball using bronchoscope. Perioperative and postoperative courses were uneventful in both patients. It was concluded that the laryngeal mask airway is useful for airway management when a catheter is inserted into a pulmonary fungus ball through the cricothyroid membrane.

Aged↗

PubMed1999

[Anesthetic management of a patient with dilated cardiomyopathy under total intravenous anesthesia with propofol and ketamine combined with continuous epidural analgesia].

We report our experience with total intravenous anesthesia (TIVA) with propofol and ketamine combined with continuous epidural analgesia in a 72-year-old-male patient with dilated cardiomyopathy scheduled for a total prostatectomy. After premedication with atropine 0.5 mg and pethidine 35 mg, anesthesia was induced with ketamine 50 mg, fentanyl 0.1 mg and using a step down method of propofol (6-->4-->2 mg.kg-1.hr-1). After hemodynamic parameters had been stabilized, the trachea was intubated. Then, 1.5% lidocaine 6 ml was injected through an epidural catheter, placed at the L 1-2 intervertebral space. Anesthesia was maintained with continuous infusion of propofol 1 mg.kg-1.hr-1 and ketamine 1 mg.kg-1.hr-1, and continuous epidural analgesia with 1.5% lidocaine 2 ml.hr-1. Hemodynamics remained stable throughout the operative procedure. No postoperative complications occurred. TIVA with propofol and ketamine in combination with epidural analgesia is useful for patients with dilated cardiomyopathy in order to maintain stable hemodynamics during anesthesia.

Aged↗

PubMed1999

[Anesthetic management for urgent endoscopy in a child with heterotopic liver transplant].

A 6-year-old boy with heterotopic liver transplant underwent urgent endoscopy under general anesthesia because of bloody stool. He was taking cyclosporin as an immunosuppressant. His hepatic function was normal and no side effects of cyclosporin were observed. Preoperative blood transfusion was performed because of severe anemia. Anesthesia was induced with midazolam 2 mg, ketamine 20 mg and fentanyl 0.05 mg, and maintained with addition of midazolam and ketamine. We did not use any inhalation anesthetics to avoid postoperative hepatic dysfunction. The endoscopy was successfully performed and the postoperative course was uneventful. We conclude that preanesthetic evaluation of immunosuppressant state and the hepatic function of transplanted liver is important for anesthetic management of a patient with heterotopic liver transplant.

Anesthesia, General↗

PubMed1999

[A patient uninformed about his illness became aware of his lung cancer when an anesthesiologist visited him for pain control].

Much has been said about the importance of informed consent in Japan, but informing cancer to the patient has not been popular so far. We, as anesthesiologists, often treat pain in cancer patients, who occasionally, are not informed about the cancer. And we sometimes have patients with whom cautious consulting is necessary. This report presents our experience with a patient uninformed about the cancer but suspicious of his lung cancer. We met him as anesthesiologists, and this made the patient convinced that he had a cancer and was about to die soon.

Adult↗

PubMed1999

[Supratentorial ectopic ependymoma: a case report].

Ependymomas usually arise from the ventricular surface and approximately two-thirds of them are infratentorial. We present an unusual case of supratentorial ependymoma located in the parietal parenchyma and exhibiting no continuity with the ventricular system. On March 30, 1998, a 63-year-old woman was admitted to our neurosurgical service because of a sudden consciousness loss attack two weeks before. On admission, neurological examination revealed no abnormal findings. Computerized tomography (CT) revealed a mass lesion of the parietal lobe which was enhanced homogeneously. Magnetic resonance imaging (MRI) also showed the mass of the parietal lobe which was iso-intense on T1-weighted images, iso and high intense on T2-weighted images and homogeneously enhanced by administration of Gd-DTPA. In the angiography, left carotid angiograms showed a tumor stain. On February 26, 1998, total removal of the tumor was performed using stereotactic craniotomy with neuronavigator and intraoperative echography. After surgery, focal radiation therapy (56Gy) was carried out. The pathological diagnosis was cellular ependymoma with partial clear cell components. Several kinds of tumor may occur in the cerebral parenchyma. We conclude, however, that ependymoma has to be included in the differential diagnosis when the tumor location is distant from the ventricles.

Brain Neoplasms↗

PubMed1999

[ADOC regimen for unresectable advanced thymic cancer].

Between 1996 and 1998, we treated 6 patients with unresectable and advanced thymic cancer (stages IVa and IVb). All received 50 mg/m2 of cisplatin and 40 mg/m2 of doxorubicin intravenously (i.v.) on day 1,0.6 mg/m2 of vincristine i.v. on day 3, and 700 mg/m2 of cyclophosphamide i.v. on day 4; ADOC regimen, respectively at 3-4 week intervals. Four patients obtained a partial response (PR) after ADOC chemotherapy and the overall clinical response rate was 67%. No life-threatening side effects were noted. In 2 patients, cisplatin plus VP-16 chemotherapy failed to demonstrate any benefits prior to the ADOC regimen. Radiotherapy was initiated after the achievement of PR in the other 2 patients. ADOC chemotherapy appears to be an effective treatment for thymic cancer.

Aged↗

PubMed1999

Automated, simplified GC/MS data processing system for organic acidemia screening and its application.

Gas chromatography mass spectrometry (GC/MS) is widely used in diagnosis of organic acidemias. However, GC/MS has not yet become a routine laboratory test, because of the complexity in interpretation of GC/MS data. We developed a personal computer-based system of automated metabolic profiling and disease detection for the screening of organic acidemias by GC/MS. The data were processed after the GC/MS analysis of urinary organic acids. In this system, 130 kinds of metabolites and 25 disorders of organic acids were enrolled for the search and detection, respectively. Metabolites were identified with methylene unit values (MU). target ions (Q- and C-ions) and their intensity ratios, and semiquantified by peak relative area (%) of the Q-ions to that of an internal standard. Metabolites whose values exceeded the cutoff of the control table were flagged as abnormal. The diseases or pathological condition were automatically evaluated by combination of the abnormal compounds. In this system, index metabolites were categorized into three groups. "AND, "OR" and "NO". The groups, "AND" and "OR" comprised essential and optional compounds, respectively, for the specific diagnosis. The third group, "NO", included compounds which must be absent to reach a diagnosis. We compiled data of MU values and mass spectrum of 130 kinds of index metabolites, and tested the usefulness of this system by analysis of 74 patients with 19 kinds of diseases. In all cases, at least a correct diagnosis could be found among the disease names outputted. We have successfully applied this to a pilot neonatal screening by GC/MS in our regional area, and acylglycine analysis by the stable isotope dilution method with tert-butyldimethylsilyl derivatization. With our system, many people can attend for screening programs using GC/MS.

Amino Acid Metabolism, Inborn Errors↗

PubMed1999

Effect of sex hormones on oxalate-synthesizing enzymes in male and female rat livers.

PURPOSE: We studied the effect of changes in sex hormones on oxalate metabolism in rats. MATERIALS AND METHODS: Adult male and female rats were administered a precursor of oxalate, and the relationship between dose and urinary oxalate was examined. Levels of sex hormones were varied in rats and glycolate oxidase (GO) and serine pyruvate aminotransferase (SPT) activities were measured under the conditions of being fed tap water or loading with 0.5% ethylene glycol. In addition, urinary oxalate excretion was evaluated. RESULTS: Ethylene glycol and glycolate increased urinary oxalate concentration in male rats dose-dependently but less in female rats. There was almost no change during glycine loading in either male or female rats. GO activity was significantly lower in intact female and gonadectomized male rats. SPT activity was slightly higher in the female than in the male controls. There were no differences in urinary oxalate excretions between male and female rats. During ethylene glycol loading, GO and SPT activities were similar to those with tap water intake. However, urinary oxalate excretion increased to two times the control value in male rats but only slightly increased in female rats. CONCLUSIONS: Sex-related differences exist in the metabolic conversion of glycolate to oxalate in rats, and GO activity is promoted by testosterone. Although difference in GO activity has no physiological effect on oxalate synthesis, GO activity affects urinary oxalate excretion during ethylene glycol loading. We could also conclude that estrogen decreases GO activity in male rats from our results.

Alcohol Oxidoreductases↗

PubMed1999

Finasteride, a 5alpha-reductase inhibitor, blocks the anticonvulsant activity of progesterone in mice.

Progesterone is an effective anticonvulsant against pentylenetetrazol (PTZ) seizures. This action is hypothesized to require the metabolic conversion of progesterone to the gamma-aminobutyric acidA receptor potentiating neuroactive steroid allopregnanolone by 5alpha-reductase isoenzymes followed by 3alpha-hydroxy oxidoreduction. We evaluated this possibility using the competitive 5alpha-reductase inhibitor finasteride. Progesterone (50-200 mg/kg, i.p.) protected mice against PTZ-induced seizures in a dose-dependent manner (ED50, 94 mg/kg). Pretreatment with finasteride (50-300 mg/kg, i.p.) produced a dose-dependent (ED50, 146 mg/kg) reversal of the protective effects of progesterone (2 x ED50 dose = 188 mg/kg). In contrast, finasteride (up to 300 mg/kg) failed to affect the anticonvulsant activity of allopregnanolone (10-30 mg/kg, i.p.; ED50, 12 mg/kg). Finasteride (up to 300 mg/kg) did not block the protective effect of high doses of progesterone (250-350 mg/kg) on tonic hindlimb extension in the maximal electroshock seizure test (progesterone ED50, 235 mg/kg). The anticonvulsant activity of progesterone against PTZ-induced seizures can be blocked by 5alpha-reductase inhibition, providing strong evidence that the anticonvulsant effect of the steroid in this model is mediated by its active metabolite allopregnanolone.

Animals↗

PubMed1998

Intracellular proteolytic cleavage of 9-cis-retinoic acid receptor alpha by cathepsin L-type protease is a potential mechanism for modulating thyroid hormone action.

We previously reported that the responsiveness of hepatocytes to thyroid hormone is markedly attenuated when they were cultured as monolayers rather than spheroids. To elucidate the mechanisms underlying the altered responsiveness, thyroid hormone receptor auxiliary proteins in the hepatocytes were analyzed by electrophoretic mobility shift assay. The major thyroid hormone receptor auxiliary protein was identified as 9-cis-retinoic acid receptor alpha (RXRalpha) in the hepatocytes regardless of the culture conditions. The cytoplasmic fraction was shown to contain a protease(s) that cleaves RXRalpha at its amino terminus. The presence of the protease in the cytosol, but not in the nucleus, was ascertained by incubating full-length 35S-labeled RXRalpha with each fraction. Using various protease inhibitors, it was shown that cathepsin L-type protease could participate in the cleavage of the RXRalpha. The enzyme activity was much higher in the monolayers than the spheroids. Inhibition of this enzyme activity in the monolayer hepatocyte resulted in the increase of nuclear RXRalpha protein and the augmentation of T3-dependent induction of spot 14 mRNA. These results suggest that the changes in cathepsin L-type protease activity in the cytosol may alter the turnover of RXRalpha in the nucleus and modify the function of steroid receptor superfamilies that heterodimerize with RXRalpha.

Animals↗

PubMed1998

Involvement of the glutamate transporter and the sodium-calcium exchanger in the hypoxia-induced increase in intracellular Ca2+ in rat hippocampal slices.

Hippocampal slices prepared from adult rats were loaded with fura-2 and the intracellular free Ca2+ concentration ([Ca2+]i) in the CA1 pyramidal cell layer was measured. Hypoxia (oxygen-glucose deprivation) elicited a gradual increase in [Ca2+]i in normal Krebs solution. At high extracellular sodium concentrations ([Na+]o), the hypoxia-induced response was attenuated. In contrast, hypoxia in low [Na+]o elicited a significantly enhanced response. This exaggerated response to hypoxia at a low [Na+]o was reversed by pre-incubation of the slice at a low [Na+]o prior to the hypoxic insult. The attenuation of the response to hypoxia by high [Na+]o was no longer observed in the presence of antagonist to glutamate transporter. However, antagonist to Na+-Ca2+ exchanger only slightly influenced the effects of high [Na+]o. These observations suggest that disturbance of the transmembrane gradient of Na+ concentrations is an important factor in hypoxia-induced neuronal damage and corroborates the participation of the glutamate transporter in hypoxia-induced neuronal injury. In addition, the excess release of glutamate during hypoxia is due to a reversal of Na+-dependent glutamate transporter rather than an exocytotic process.

2-Amino-5-phosphonovalerate↗

PubMed1998

Novel mutations of the glutaryl-CoA dehydrogenase gene in two Japanese patients with glutaric aciduria type I.

We identified three different point mutations in the glutaryl-CoA dehydrogenase (GCDH) gene in two unrelated Japanese patients with glutaric aciduria type I (GA-I). One patient was a homozygote for Arg355His and the other a compound heterozygote for Ser305Leu and Met339Val. Arg355His and Met339Val are mutations hitherto undescribed, and all three mutations are predicted to alter the secondary structure of GCDH. Molecular analysis is useful for definite diagnosis and/or prenatal diagnosis of GA-I.

Amino Acid Metabolism, Inborn Errors↗

PubMed1998

Role of the outermost subdomain of Salmonella flagellin in the filament structure revealed by electron cryomicroscopy.

A mutant strain of Salmonella typhimurium, SJW46, has flagellar filaments supercoiled in the same form as the wild-type strain, SJW1103, and swims normally. However, its flagellar filaments are mechanically unstable and show anomalous behaviors of polymorphism. Flagellin from SJW46 has a large central deletion from Ala204 to Lys292 of SJW1103 flagellin, which has been thought to be located in the outer surface of the filament. Since the filament structure is determined by intersubunit interactions of the terminal regions in the densely packed core of the filament, no serious involvement of the deleted portion was expected in the filament stability and polymorphism. In order to locate the deleted portion and to understand the underlying mechanism of these anomalous characteristics, we carried out structure analysis of the L-type straight filament reconstituted from a mutant flagellin of SJW46 (SJW46S) and compared the structure with that of the SJW1660 filament, which is also the L-type but composed of flagellin with no deletion. The deleted portion was identified as the outermost subdomain, and the structure in the core region showed no appreciable differences. The structure revealed the previously identified folding of flagellin in further detail, and the significance of intersubunit interactions between outer domains, which are present in the SJW1660 filament but absent in the SJW46 filament. This suggests that these contacts have a significant contribution to the filament stability and polymorphic behavior, despite the fact that the contacting surface area occupies only a minor portion of the whole intersubunit interactions.

Caulobacter crescentus↗

PubMed1998

A novel type of vascular endothelial growth factor, VEGF-E (NZ-7 VEGF), preferentially utilizes KDR/Flk-1 receptor and carries a potent mitotic activity without heparin-binding domain.

Vascular endothelial growth factor (VEGF) mediates endothelial cell proliferation, angiogenesis, and vascular permeability via the endothelial cell receptors, KDR/Flk-1 and Flt-1. Recently, a gene encoding a polypeptide with about 25% amino acid identity to mammalian VEGF was identified in the genome of Orf virus (OV), a parapoxvirus that affects sheep and goats and occasionally, humans, to generate lesions with angiogenesis. In this study, we examined the biological activities and receptor of OV-derived NZ-7 VEGF (VEGF-E). VEGF-E was found to be a dimer of about 20 kDa with no basic domain nor affinity for heparin column, similar to VEGF121 subtype. VEGF121 has 10-100-fold less endothelial cell mitotic activity than VEGF165 due to lack of a heparin-binding basic region. Interestingly, however, VEGF-E showed almost equal levels of mitotic activity on primary endothelial cells and vascular permeability activity as VEGF165. Furthermore, VEGF-E bound KDR/Flk-1 (VEGFR-2) and induced its autophosphorylation to almost the same extent as VEGF165, but did not bind Flt-1 (VEGFR-1) nor induce autophosphorylation of Flt-1. These results indicate that VEGF-E is a novel type of endothelial growth factor, utilizing only one of the VEGF receptors, and carrying a potent mitogenic activity without affinity to heparin.

Animals↗

PubMed1998

Mapping of the sites involved in ligand association and dissociation at the extracellular domain of the kinase insert domain-containing receptor for vascular endothelial growth factor.

The kinase insert domain-containing receptor (KDR) for vascular endothelial growth factor (VEGF) has been shown to be involved in vasculogenesis and angiogenesis. This receptor is characterized by seven immunoglobulin (Ig)-like domains within its extracellular region. To identify the domains involved in VEGF binding, we constructed various deletion mutants of the extracellular region fused with the crystallizable fragment portion of an IgG and then examined the binding affinity with VEGF by means of the BIAcore biosensor assay. Deletion of the COOH-terminal two or three Ig-like domains out of a total of seven affected ligand dissociation rather than association. Further deletion of the fourth domain caused a drastic decrease in the association rate. Binding ability was abolished completely with removal of the third domain. The mutant KDR proteins lacking the NH2-terminal Ig-like domain exhibited a slightly higher association rate compared with those of the mutants having this domain. Deletion of the first two NH2-terminal Ig-like domains caused a drastic reduction in the association rate, but affinity to VEGF was retained. These results suggest that the third Ig-like domain is critical for ligand binding, the second and fourth domains are important for ligand association, and the fifth and sixth domains are required for retention of the ligand bound to the receptor molecule. The first Ig-like domain may regulate the ligand binding.

Binding Sites↗

PubMed1998

Relationship between structure and substrate-chain-length specificity of mitochondrial very-long-chain acyl-coenzyme A dehydrogenase.

Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) is one of four enzymes which catalyze the initial step of the mitochondrial beta-oxidation with different but overlapping substrate-chain-length specificities. A450P, a variant of VLCAD identified in a patient with VLCAD deficiency, showed abnormal substrate-chain-length specificity. Based on this mutation, we studied the relationship between the structure and substrate-chain-length specificity of VLCAD. When VLCAD was treated with trypsin, a homodimer protein of a 48-kDa polypeptide deprived of both the amino-terminal 22 amino acids and the carboxyl-terminal 145 amino acids of VLCAD was obtained. Six Ala450 variants and tryptic-VLCAD exhibited similar substrate specificities. Effects of long-chain acyl-CoA on the tryptic cleavage and changes in the catalytic properties by deprivation of the carboxyl-terminal region suggest that this region interacts with the fatty acyl moiety of long-chain acyl-CoA. Thus, both Ala450 and the carboxyl-terminal region, which are not shared by other acyl-CoA dehydrogenases, are likely to be the determinating factors in the substrate-chain-length specificity of VLCAD.

Acyl Coenzyme A↗

PubMed1998

Evidence of local conformational fluctuations and changes in bacteriorhodopsin, dependent on lipids, detergents and trimeric structure, as studied by 13C NMR.

We examined how the local conformation and dynamics of [3-13C]Ala-labeled bacteriorhodopsin (bR) are altered as viewed from 13C NMR spectra when the natural membrane lipids are partly or completely replaced with detergents. It turned out that the major conformational features of bR, the alphaII-helices, are generally unchanged in the delipidated or solubilized preparations. Upon partial delipidation or detergent solubilization, however, a significant conformational change occurs, ascribed to local conversion of alphaII-->alphaI-helix (one Ala residue involved), evident from the upfield displacement of the transmembrane helical peak from 16.4 ppm to 14.5 ppm, conformational change (one or two Ala residues) within alphaII-helices from 16.4 to 16.0 ppm, and acquired flexibility in the loop region (especially at the F-G loop) as manifested from suppressed peak-intensities in cross-polarization magic angle spinning (CP-MAS) NMR spectra. On the other hand, formation of monomers as solubilized by Triton X-100, Triton N-101 and n-dodecylmaltoside is characterized by the presence of a peak at 15.5 ppm and a shifted absorption maximum (550 nm). The size of micelles under the first two conditions was small enough to yield 13C NMR signals observable by a solution NMR spectrometer, although 13C CP-MAS NMR signals were also visible from a fraction of large-sized micelles. We found that the 16.9 ppm peak (three Ala residues involved), visible by CP-MAS NMR, was displaced upfield when Schiff base was removed by solubilization with sodium dodecyl sulfate, consistent with our previous finding of bleaching to yield bacterioopsin.

Bacteriorhodopsins↗

PubMed1998

Significant expression of vascular endothelial growth factor/vascular permeability factor in mouse ascites tumors.

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is believed to be a potent mediator of peritoneal fluid accumulation and angiogenesis and of tumor growth in ascites tumor. Such roles, however, have not been generally established because of insufficient quantitative and systemic analyses. To address this, we examined the expression of VEGF in 13 mouse ascites tumors (5 sarcomas, 3 carcinomas, 2 lymphomas, 1 leukemia, 1 mastocytoma, and 1 plasmacytoma). Using a newly developed sensitive and specific radioreceptor binding assay and functional assays, we found that active VEGF was significantly accumulated (6-850 ng/ml) in the ascites fluids of all 13 tumors. VEGF concentrations are higher in the tumors of sarcoma and carcinoma origin (430.4 +/- 234.2 ng/ml) than in those of lymphoma and hematological tumor origin (19.2 +/- 10.45 ng/ml). VEGF that accumulated in the peritoneal fluids or expressed in the ascites tumor cells was easily visualized with immunoprecipitation Western blot analysis with a rough correlation to the expression levels of VEGF gene in these tumor cells, suggesting that the tumor cells, at least in part, contributed to the production of the VEGF that accumulated in the ascites fluid. Most ascites tumors expressed VEGF; the 164-amino acid isoform was predominant, the 120-amino acid isoform was less abundant, and the 188-amino acid isoform was least abundant. Several representative ascites tumors expressed similar, if not higher, levels of VEGF when they were cultured at normoxic states, suggesting that they expressed VEGF at high levels in a constitutive manner. The microvessel densities in the peritoneal walls of tumor-bearing mice, which are significantly higher than those in normal mice, basically correlated to but did not parallel the VEGF concentrations in their respective ascites fluids. Thus, a complicated relationship may exist between the VEGF production and angiogenesis associated with ascites tumor in vivo. Taken together, our observations suggest that VEGF plays a fundamental role in ascites tumor formation; however, its importance may vary according to tumor origin.

Animals↗