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Biomedical subjects

T Miyazawa

Publications and source records attributed to T Miyazawa.

At least 271 records · Page 15Linked to original sources
PubMed1994

Stereotactic gamma-thalamotomy with a computerized brain atlas: technical case report.

Radiosurgical stereotactic thalamotomy was performed in a patient with parkinsonian tremor with a computerized stereotactic brain atlas, which was transformed to fit the patient's thin-sliced magnetic resonance image to select an optimal target in the nucleus ventralis intermedius of the thalamus. The patient's tremor and rigidity disappeared and have not appeared again for more than 1 year since the eighth postoperative month. A method for converting the presurgically planned stereotactic coordinates in the atlas coordinate system to the coordinates in the frame coordinate system is described.

Aged↗
PubMed1994

Cytotoxicity of 1,3-dichloropropene and cellular phospholipid peroxidation in isolated rat hepatocytes, and its prevention by alpha-tocopherol.

1,3-Dichloropropene induced time- and dose-dependent toxicity and lipid peroxidation were examined in isolated rat hepatocytes. HPLC method with chemiluminescence detection (CL-HPLC) was employed to determine phosphatidylcholine hydroperoxide (PCOOH) and phosphatidylethanolamine hydroperoxide (PEOOH) contents. The release of lactate dehydrogenase (LDH) as a toxicological parameter was significantly increased after 90 min incubation at 1 mM of 1,3-dichloropropene and after 60 min incubation at 5 mM, respectively. The cellular PCOOH and PEOOH contents were increased after 90 min incubation at 1 mM of 1,3-dichloropropene, and after 15 min for PCOOH and 30 min for PEOOH at 5 mM, respectively. The increase of cellular phospholipid hydroperoxide preceded the cytotoxicity. Hepatotoxicity was effectively prevented by preincubation with d,1-alpha-tocopherol (alpha-toc.) accompanied by prevention of the membrane phospholipid peroxidation. In conclusion, the peroxidation of phospholipid preceded cytotoxicity, and cytotoxicity was effectively prevented by alpha-toc. These results indicated that the peroxidative degradation of membrane phospholipid is one of the main causes of cytotoxicity by 1,3-dichloropropene.

Allyl Compounds↗
PubMed1994

Cytotoxicity of chlorinated hydrocarbons and lipid peroxidation in isolated rat hepatocytes.

The effects of 11 chlorinated hydrocarbons on toxicological parameters and lipid peroxidation were examined in cultured rat hepatocytes. The cytotoxicity was evaluated by measuring the lactate dehydrogenase (LDH) released and the protein amount in cells attached to culture dishes. Phosphatidylcholine hydroperoxide (PCOOH) and phosphatidylethanolamine hydroperoxide (PEOOH) levels were determined by HPLC with chemiluminescence detection (CL-HPLC). Severe cytotoxicity was observed under the presence of the carbon tetrachloride, 1,1,1-trichloroethane, tetrachloroethylene and 1,3-dichloropropene in a concentration of 10 mM. The cellular PCOOH and PEOOH levels were remarkably increased (more than 4 times) by adding these 4 chlorinated hydrocarbons. The other 7 chlorinated hydrocarbons examined did not cause any change on the cellular phospholipid hydroperoxide levels, and showed lower or no cytotoxicity at a concentration of 10 mM. The peroxidative degradation of membrane phospholipids may play an important role in causing the cytotoxicity of some chlorinated hydrocarbons.

Animals↗
PubMed1994

Comparison of the Rev transactivation of feline immunodeficiency virus in feline and non-feline cell lines.

The Rev protein of feline immunodeficiency virus (FIV) differentially transactivates the expression of viral structural proteins by allowing the accumulation of unspliced and singly spliced viral mRNA in cytoplasm via the Rev response element (RRE) at the end of env. To investigate the role of rev gene of FIV for the virus life cycle and cell tropism, we constructed the Rev expression plasmids, and functional activity of the Rev was assayed by using chloramphenicol acetyltransferase (CAT) assay system in feline and non-feline cell lines. Although the FIV Rev protein showed high transactivity to result in enhanced CAT production in a feline cell line, the productions of the CAT in non-feline cell lines were significantly lower than that in the feline cell line. These results indicate that specific cellular factor(s) present in feline cell line is required for the FIV Rev full-action and also suggest that the Rev action plays one of the important roles in determining the FIV cell tropism.

Animals↗
PubMed1994

Growth properties of a feline immunodeficiency virus mutant which lacks an AP-1 binding site in primary peripheral blood mononuclear cells.

Thirty-one base pairs (bp) containing putative AP-1 and AP-4 binding sequences in the U3 region of feline immunodeficiency virus (FIV) long terminal repeat (LTR) were deleted from an infectious molecular clone of FIV for construction of a mutant virus, and the replication rate and the cytopathogenic activity of the virus were compared with those of the wild type virus in concanavalin-A (Con-A) stimulated primary feline peripheral blood mononuclear cells (fPBMCs). It was found that the replication rate and cytopathogenic activity of the mutant were almost the same as those of the wild type. The deletion of the mutant virus was stable during the infection experiments. From these data, we concluded that the 31 bp fragment in the LTR is not required for the replication of FIV in Con-A stimulated primary fPBMC.

Animals↗
PubMed1994

Comparative functional analysis of the various lentivirus long terminal repeats in human colon carcinoma cell line (SW480 cells) and feline renal cell line (CRFK cells).

Basal promoter activities of various lentiviral long terminal repeats (LTRs) in a human colon carcinoma cell line (SW480 cells) and a feline renal cell line (CRFK cells) were examined by the chloramphenicol acetyltransferase (CAT) assay using the LTR-CAT reporter plasmids. In SW480 cells, the basal promoter activities induced by LTRs of visna virus, caprine arthritis-encephalitis virus (CAEV), and simian immunodeficiency virus (SIVAGM) were moderate, and those induced by LTRs of human immunodeficiency virus (HIV) type 1 (HIV-1) and HIV type 2 (HIV-2) were low. However, the activity induced by the LTR of feline immunodeficiency virus (FIV) was extremely low. In CRFK cells, the basal promoter activities induced by LTRs of visna virus, CAEV and SIVAGM were relatively high, and those induced by LTRs of HIV-1, HIV-2 and FIV were moderate. From these data, although the structure of the LTR of FIV is reported to be similar to that of visna virus and CAEV, the function of the LTR of FIV is rather quite different from that of the LTR of these viruses.

Animals↗
PubMed1994

Decreased gastric secretory functions in diabetic patients with autonomic neuropathy.

A total of 37 subjects consisted of 10 healthy subjects (Group III), 15 diabetic patients without autonomic neuropathy (Group II), and 12 diabetic patients with autonomic neuropathy including gastroparesis in 6 cases (Group I). All three groups were comparable in age. In order to clarify the gastric function in diabetic patients with autonomic neuropathy, secretion of serum gastrin, gastric secretory function, endoscopic Congo red test of fundic glands, and coefficiency of variance of electrocardiographic beat-to-beat intervals (C.V. R-R) were examined. In Group I, 5 patients had hypergastrinemia, but its elevation was inhibited when an acid solution was injected into the stomach. Gastric secretion and C.V. R-R were markedly lower in Group I, compared with Groups II and III. In Group I, the area of fundic glands (parietal cells) was reduced considerably. The C.V. R-R was significantly correlated with fasting serum gastrin concentration and with maximal acid output. From these results, in diabetic patients with autonomic neuropathy (vagal neuropathy), gastric acid secretion in response to tetragastrin stimulation was lowered with a reduction in area of fundic gland distribution. Hypergastrinemia may reflect a negative feedback mechanism responding to decreased acidity of gastric content in the antrum.

Adult↗
PubMed1994

"Undifferentiated" cerebral primitive neuroectodermal tumor in a young adult--case report.

A 21-year-old female presented with a cerebral primitive neuroectodermal tumor (PNET) without either glial or neuronal differentiation, who has survived for 27 months without neurological deficit following total removal of the tumor, radiotherapy, and intensive chemotherapy. Both immunohistochemical and ultrastructural studies are important for the diagnosis of PNET. "Undifferentiated" PNET may be a distinct entity from common PNET which shows either glial or neuronal differentiation or both.

Adult↗
PubMed1994

The effect of natural carotenoid (palm fruit carotene) intake on skin lipid peroxidation in hairless mice.

To study the effect of palm fruit carotene intake on skin lipid peroxidation, hairless mice were given ad libitum palm fruit carotene, beta-carotene, or vehicle emulsions for 15 weeks in which the carotene (0.005%, w/w) was suspended in drinking water, and then their dorsal skin was exposed to ultraviolet ray (UV). The carotene content of the skin was increased by the oral intake of palm fruit carotene or beta-carotene. In carotene-drinking mice, before the UV irradiation, the amount of thiobarbituric acid-reacting substances (TBARS) in the skin was lower than that of control (carotene untreated) mice. The skin TBARS immediately after the UV irradiation was lower in carotene-treated mice than in control mice. At 24 h after irradiation, the skin TBARS of mice that orally received palm fruit carotene was lower than that of beta-carotene mice. Immediately after the UV irradiation, the skin carotene content transiently decreased but gradual recovery was observed at 48 h. In palm fruit carotene-treated mice, the rate of carotene recovery after UV irradiation was higher than in beta-carotene-treated mice. Retinol found in the skin had also decreased after UV irradiation, and recovered gradually in both carotene-drinking groups within 48 h. These results suggested that the carotene intake, especially palm fruit carotene, prevented skin lipid peroxidation in hairless mice.

Animals↗
PubMed1994

The antioxidant effect of palm fruit carotene on skin lipid peroxidation in guinea pigs as estimated by chemiluminescence-HPLC method.

To study the antioxidant effect of palm fruit carotene on skin lipid peroxidation, the guinea pigs were orally fed ad libitum palm fruit carotene, beta-carotene, or vehicle emulsions, in which carotene (0.05%, w/w) was suspended in drinking water. After treatment of carotene for 12 weeks, animals were exposed to ultraviolet ray (UV), and squalene monohydroperoxide (SqOOH)/squalene (Sq) ratios in the skin lipid were analyzed using the chemiluminescence-HPLC method. Carotene accumulation was found in the skin of guinea pigs that were orally administered palm fruit carotene or beta-carotene. After UV irradiation, especially immediately after, the rise in the SqOOH/Sq ratio was effectively suppressed in both carotene-drinking groups in contrast with the control (carotene-untreated) group. An inverse correlation between the carotene content and the SqOOH/Sq ratio in the skin was also observed. The results suggested that palm fruit carotene intake prevents skin lipid peroxidation caused by UV irradiation.

Animals↗
PubMed1994

[Pleuropulmonary aspergillosis with defective neutrophil functions--G-CSF effects on neutrophil functions].

A 66-year-old man was admitted to our hospital with productive cough and fever. Chest X-ray films showed pleural thickening of the right apex and calcification of the lung field. Antibiotic therapy was administered but no improvement was obtained. Chest CT scan revealed pleural thickening with effusion in the right apex. Needle aspiration biopsy was performed and Aspergillus fumigatus was isolated from pleural fluid. We began pleural drainage and intrapleural infusion of miconazole, with systemic administration of miconazole, amphotericin B and fluconazole. In spite of normal bone marrow findings, the neutrophil functions, NAP score and phagocytosis, of the patient were found to be subnormal. We commenced to treatment with granulocyte colony stimulating factor and his neutrophil functions improved (NAP score: 156-->309.5, phagocytosis: 64.9-->70.0%). However, his fever persisted and he died following cardiopulmonary arrest. Autopsy revealed Aspergillus mycelia invading the visceral pleura. No intrapulmonary lesions caused by Aspergillus were found.

Aged↗
PubMed1994

[Clinical efficacy of arbekacin in deep MRSA infection. Including follow-up study after the termination of chemotherapy].

We analyzed the efficacy of arbekacin (ABK) using monotherapy or combined therapy on deep MRSA infection to find the most adequate usage of the drug. We also followed-up the isolation incidence of MRSA after the end of chemotherapy. The results are summarized as follows: 1. Clinical efficacy of ABK on 29 pneumonia and 3 septicemia due to MRSA was 42.9% in ABK monotherapy (9 patients), 62.5% in combined therapy with ABK and minocycline (9 patients), 100% with ABK and imipenem/cilastatin (IPM/CS) (7 patients), and 100% with ABK and other drugs (7 patients). 2. As for microbiological efficacy, combined therapy with ABK and IPM/CS or other drug was superior to other methods. Among patients from whom two or more species of bacteria were isolated, causative bacteria persisted in many cases, and some replacements occurred. 3. Kidney functions deteriorated in two patients that underwent monotherapy or combined therapy with ABK and IPM/CS, but they recovered when therapy was completed the completion. 4. In the three month follow-up study after ABK therapy, we found four cases of renewed infections after disappearance of MRSA. When just decreases in the number of MRSA resulted upon the chemotherapy, the relapse occurred in all cases. 5. Above results indicate that ABK is effective in MRSA infection, and combined therapy with beta-lactams is superior to other methods in serious MRSA infections. We also suggest that chemotherapy should be continued until the complete disappearance of MRSA is achieved.

Adult↗
PubMed1994

Isolation, sequence and expression of a cDNA encoding the alpha-chain of the feline CD8.

We have cloned, sequenced and expressed a cDNA encoding the alpha-chain of feline CD8. This clone, named FT8-10, has an open reading frame with 720 nucleotides in length encoding a protein with 239 amino acid residues. Sequence analysis has revealed that the feline CD8 alpha-chain (CD8 alpha) shares significant homology with human (T8/Leu-2), bovine (BoCD8), rat (MRC OX8) and mouse (Lyt-2) CD8 alpha subunits. Cysteine residues as well as the tyrosine kinase p56lck binding site are well conserved. Besides, no putative N-linked glycosylation site was found. Interestingly, immunofluorescence analysis of COS-7 cells transfected with feline CD8 alpha expression plasmid driven by SR alpha promoter showed that the expressed feline CD8 alpha cross-reacted with an anti-human CD8 alpha monoclonal antibody OKT8, but did not react with an anti-feline monoclonal antibody, FT-2, which is thought to recognize the feline analogue of the human T8/Leu-2 and murine Lyt-2 molecules expressed on cytotoxic/suppressor T cells.

Amino Acid Sequence↗
PubMed1994

[Temperature effect on ischemic brain injury].

The effect of manipulating the brain temperature during cerebral ischemia was investigated in Wistar rats subjected to 30 min 4-vessel occlusion. Three brain temperature profiles were compared: 1. Spontaneous decrease in brain temperature during ischemia from 36 to 31 degrees C (spontaneous hypothermia; n = 5); 2. Constant brain temperature of 30 degrees C induced by selective head cooling (induced hypothermia; n = 5); and 3. Constant brain temperature of 36 degrees C induced by selective heating of the head (normothermia; n = 5). The core temperature was maintained constant at 37 degrees C in all groups. In the spontaneously hypothermic brains, 16% of the CA1 neurons survived after 30 min ischemia. Induced hypothermia significantly increased this percentage to 69%, but maintenance of the brain temperature at normothermia decreased neuronal survival to 1%. Normothermia of the brain also led to morphological injury outside the vulnerable regions, greater variability of the morphologic lesions, an increase in mortality, a marked loss of body weight, and prolongation of EEG suppression, as compared to in both hypothermic groups. These findings clearly demonstrate that maintaining the brain temperature at normothermia by selective heating of the head aggravates ischemic injury and, in consequence, should not be used to investigate the effectiveness of protective drugs for brain ischemia.

Animals↗
PubMed1993

Lipoxygenase in soybean seedlings catalyzes the oxygenation of phospholipid and such activity changes after treatment with fungal elicitor.

Lipoxygenase (LOX) activities in the crude extracts of soybean cotyledons on phospholipid were measured by a chemiluminescence (CL) assay system. The activity of LOX on phospholipid increased at 6 h after treatment with fungal elicitor, whereas the activity in the control experiment without elicitor treatment declined with incubation. A rise of LOX activity at 6 h incubation is considered to be induced by the elicitor treatment. The LOX fraction obtained from soybean cotyledons at 6 h after elicitation by a DEAE column chromatography was reacted with 1-palmitoyl-2-linoleoyl-phosphatidylcholine substrate. The reaction product was analyzed by HPLC equipped in series with a UV (205 nm) and a CL detector. Most of the substrate was converted to a hydroperoxy compound. By the CL-HPLC analysis after transesterification of reaction product and by mass spectrum of the trimethylsilyl derivative after reduction of methyl ester confirmed that the linoleic moiety was subjected to oxygenation at 13-position. The steric analysis of menthoxyacetyl derivative prepared from hydroxy fatty acid methyl ester showed S configuration. These findings suggest that the oxygenation of membrane lipids in biological plant tissues might be initiated by the direct action of LOX.

Chromatography, High Pressure Liquid↗
PubMed1993

A modified uridine in the first position of the anticodon of a minor species of arginine tRNA, the argU gene product, from Escherichia coli.

The argU (dnaY) gene product, a minor tRNA(Arg), from Escherichia coli has the anticodon N*CU with an unidentified modified nucleoside N* in position 34 [Kiesewetter, S., Fisher, W. & Sprinzl, M. (1987) Nucleic Acids Res. 15, 3184]. In the present study, argU tRNA was purified from E. coli A19 strain and nucleoside N* was characterized by the TLC and HPLC analyses. Nucleoside N* was found to be different from any naturally occurring modified nucleosides. From unfractionated E. coli tRNA species, nucleoside N* was prepared in an amount sufficient for 1H-NMR experiments. By the analyses of one-dimensional and two-dimensional NMR spectra, nucleoside N* was suggested to be 5-methylaminomethyluridine (mnm5U), which was confirmed by comparison with a chemically synthesized preparation of mnm5U. Thus, the occurrence of mnm5U in mature tRNA was found for the first time. Further, the modification of U(34) to mnm5U in this tRNA was found to contribute to the strict recognition of two degenerate codons terminating in A and G.

Anticodon↗
PubMed1993

Chemical modification and mutagenesis studies on zinc binding of aminoacyl-tRNA synthetases.

Thermus thermophilus methionyl-tRNA synthetase consists of two identical subunits with a potential Zn(2+)-binding sequence of Cys-X2-Cys-X13-Cys-X2-His (Nureki, O., Muramatsu, T., Suzuki, K., Kohda, D., Matsuzawa, H., Ohta, T. Miyazawa, T., and Yokoyama, S. (1991) J. Biol. Chem. 266, 3268-3277). Upon chemical modification of the 3 Cys residues of T. thermophilus MetRS with sodium p-(hydroxymercuri)phenylsulfonate, one Zn2+ ion was released from one subunit of the molecule, as monitored with 4-(2-pyridylazo)resorcinol. Site-directed mutagenesis of Cys and His residues in the Zn(2+)-binding sequence reduced the aminoacylation activity; the kcat value was markedly decreased, and the Km values for L-methionine and tRNAf(Met) were increased. Similarly, Cys modification released two Zn2+ ions from T. thermophilus and Escherichia coli isoleucyl-tRNA synthetases and E. coli threonyl-tRNA synthetase, which have Zn(2+)-binding motifs, and impaired their activities. By contrast, three other aminoacyl-tRNA synthetases that lack Zn(2+)-binding motif neither released Zn2+ ion nor lost their activities upon Cys modification. These results indicate that the Zn(2+)-binding sequences are important for catalysis and recognition in the aminoacylation reactions of a subgroup of aminoacyl-tRNA synthetases.

Acylation↗