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Biomedical subjects

M Sakurai

Publications and source records attributed to M Sakurai.

At least 271 records · Page 15Linked to original sources
PubMed1996

Inductions of Cu/Zn superoxide dismutase- and nitric oxide synthase-like immunoreactivities in rabbit spinal cord after transient ischemia.

The distributions and inductions of Cu/Zn superoxide dismutase (SOD), neuronal and endothelial nitric oxide (NO) synthase (nNOS and eNOS), and nitrotyrosine (NT) were immunohistochemically examined in rabbit spinal cords after 5 and 15 min of transient ischemia. The neurons in the anterior horns (AH) were selectively lost 7 days after 15-min ischemia as compared with those of sham-operated controls. In the normal spinal cords, a number of neurons in the AHs were positive for the nNOS, and only slightly positive for the Cu/Zn SOD and the eNOS. Immunoreactivities for the proteins were induced at 8-24 h both after 5- and 15-min ischemia. In contrast, NT-like immunoreactivity was negative both in the normal and postischemic spinal cords. These results suggest that Cu/Zn SOD- and nNOS-, and eNOS-like immunoreactivities are induced, but that, even though an interaction of Cu/Zn SOD with NO could be present, NT was not detected in the motor neurons in the rabbit spinal cords after transient ischemia. Other factors could be required for NT formation found in degenerative motor neuron death in humans.

Animals↗
PubMed1996

Constitutive activation of NF-kappa B is essential for transformation of rat fibroblasts by the human T-cell leukemia virus type I Tax protein.

Human T-cell leukemia virus type I (HTLV-I) encodes a 40 kDa trans-acting protein, Tax, that regulates transcription of both the proviral and cellular genes, and can transform rat fibroblasts. To determine the functional importance of its trans-acting capacities in cell transformation, we have examined two representative pathways of transcriptional activation--HTLV-I long terminal repeat (LTR) mediated and NF-kappa B dependent--by mutational analysis of Tax. In contrast to a previous report, mutants lacking the ability to activate an NF-kappaB-dependent promoter failed to transform rat fibroblasts, whereas a mutation which abolishes the HTLV-I LTR-mediated trans-activation demonstrated a wild-type capacity for cell transformation. Stable expression of Tax competent for transformation caused enhanced DNA binding of NF-kappa B in rat fibroblasts. We also demonstrate that stable co-expression of the NFKB2 precursor, known as a member of the I kappa B proteins, with wild-type Tax blocked transformation as well as eliminated aberrant NF-kappaB activation by Tax without interference with the HTLV-I LTR-mediated trans-activation. Our results indicate that constitutive activation of NF-kappa B is essential for Tax-mediated transformation of rat fibroblasts.

Amino Acid Sequence↗
PubMed1996

Cartilaginous endplate in cervical disc herniation.

STUDY DESIGN: Cervical herniated disc tissue obtained at surgery for myelopathy and intervertebral discs from autopsy cases were examined histologically. OBJECTIVES: To clarify the characteristic histology of cervical disc herniation and the processes by which herniated masses are produced. SUMMARY OF BACKGROUND DATA: Except for nucleus pulposus or anulus fibrosus, no other disc tissue has been described histologically in the cervical spine. METHODS: Twenty-one herniated cervical discs from 20 surgical cases (patients aged 37-68 years) and mid-sagittal slabs of 135 cervical discs from 41 autopsy cases (aged 20-85 years) were examined histologically. RESULTS: All the surgical specimens had cartilaginous endplate fragments together with nucleus pulposus or anulus fibrosus. Of the autopsy disc specimens, 61% had a horizontal cleft longer than two thirds of the anteroposterior diameter of the disc, and 49% had one or more vertical clefts extending to the cartilaginous endplate. Thirty-three percent showed separation of the cartilaginous endplate, and 15% had a herniated mass including parts of the cartilaginous endplate. These abnormal features increased with aging. The same order of decreasing frequency from horizontal cleft formation through herniation was observed in all decades. CONCLUSIONS: The cartilaginous endplate-type of herniation is the predominant type of herniation in the cervical spine. It results from horizontal and vertical cleft formations of the disc.

Adult↗
PubMed1996

Tumoral calcinosis in the upper cervical spine: a case report.

STUDY DESIGN: An elderly women with tumoral calcinosis between the C1 posterior arch and the C2 lamina is reported. OBJECTIVES: To describe a rare occurrence of tumoral calcinosis in the spine and discuss its pathomechanism. SUMMARY OF BACKGROUND DATA: Tumoral calcinosis is a rare condition occurring predominantly in the juxtaarticular regions of the extremities. Involvement of the spine has been reported in only one case in the lumbar spine. The calcium phosphate crystals that have been identified are those of hydroxyapatite. METHODS: The calcified material was removed, and its crystalline phase was analyzed. RESULTS: Neck pain was relieved by removal of the calcified material. Scanning electron microscopy and energy-dispersive x-ray microanalysis revealed that the material consisted of crystals of calcium pyrophosphate dihydrate. CONCLUSIONS: Tumoral calcinosis should be included among the clinical presentations of calcium pyrophosphate dihydrate crystal deposition disease.

Aged↗
PubMed1996

Structure of a loop-deleted variant of 3-isopropylmalate dehydrogenase from Thermus thermophilus: an internal reprieve tolerance mechanism.

A loop-deleted mutant form of 3-isopropylmalate dehydrogenase from Thermus thermophilus was constructed to investigate the relationship between the flexibility of the structure and the thermostability of the enzyme. The structure of the mutant enzyme was determined by X-ray crystallography and was found to be almost the same as that of the native enzyme with a reduced temperature factor. Although the mutant protein had lost the flexible loop, its function and thermostability had remained unchanged. This phenomenon can be explained by an internal reprieve tolerance mechanism.

Journal Article↗
PubMed1996

A stable intermediate in the thermal unfolding process of a chimeric 3-isopropylmalate dehydrogenase between a thermophilic and a mesophilic enzymes.

The thermal unfolding process of a chimeric 3-isopropylmalate dehydrogenase made of parts from an extreme thermophile, Thermus thermophilus, and a mesophile, Bacillus subtilis, enzymes was studied by CD spectrophotometry and differential scanning calorimetry (DSC). The enzyme is a homodimer with a subunit containing two structural domains. The DSC melting profile of the chimeric enzyme in 20 mM NaHCO3, pH 10.4, showed two endothermic peaks, whereas that of the T. thermophilus wild-type enzyme had one peak. The CD melting profiles of the chimeric enzyme under the same conditions as the DSC measurement, also indicated biphasic unfolding transition. Concentration dependence of the unfolding profile revealed that the first phase was protein concentration-independent, whereas the second transition was protein concentration-dependent. When cooled after the first transition, the intermediate was isolated, which showed only the second transition upon heating. These results indicated the existence of a stable dimeric intermediate followed by the further unfolding and dissociation in the thermal unfolding of the chimeric enzyme at pH 10-11. Because the portion derived from the mesophilic isopropylmalate dehydrogenase in the chimeric enzyme is located in the hinge region between two domains of the enzyme, it is probably responsible for weakening of the interdomain interaction and causing the decooperativity of two domains. The dimeric form of the intermediate suggested that the first unfolding transition corresponds to the unfolding of domain 1 containing the N- and C-termini of the enzyme, and the second to that of domain 2 containing the subunit interface.

3-Isopropylmalate Dehydrogenase↗
PubMed1996

Characteristic histologic features of human hepatocellular carcinoma with mutant p53 protein.

To characterize hepatocellular carcinoma (HCC) cells with mutant (m) p53 protein histologically, we examined 68 main nodules and 20 accessory lesions of 72 patients with HCC who underwent hepatic resection between October 1990 and September 1993. Some sections were fixed in periodate-lysine-paraformaldehyde, embedded in OCT compound, and stained with the mouse monoclonal antibody PAb1801 to m-p53 protein by the immunoperoxidase technique with avidin-biotin complexes. Other sections were fixed in 20% buffered formalin, embedded in paraffin, and stained with the mouse monoclonal antibody DO-1 to m-p53 protein in the same way. Lesions in which cells had nuclei stained for m-p53 protein were defined as being positive for the protein; 25 of the 68 main nodules and 14 of the 20 accessory lesions were positive. Large main nodules were more likely to be positive than small ones. Microscopic examination showed that a larger proportion of poorly differentiated main nodules than well differentiated nodules were positive. Larger proportions of main nodules with extracapsular invasion, septa, portal thrombi, or intrahepatic metastases were positive than main nodules without these features. Accessory lesions that seemed to be metastatic were almost all positive, but few accessory lesions that seemed to be of multicentric occurrence were positive. Our results suggest that lesions with m-p53 protein had a high grade of malignancy and metastasized readily.

Adult↗
PubMed1996

Deoxycytidine kinase mRNA levels in leukemia cells with competitive polymerase chain reaction assay.

Deoxycytidine kinase (dCyd kinase) is important for the phosphorylation of several different nucleoside antimetabolites. To understand the significance of dCyd kinase levels in chemotherapy, dCyd kinase mRNA levels were evaluated in several cells with a quantitative competitive polymerase chain reaction (PCR) assay. dCyd kinase catalytic activity and intracellular ara-CTP production were also compared with the levels of dCyd kinase mRNA. The assay was able to show: (i) that dCyd kinase catalytic activity and dCyd kinase mRNA levels were correlated in cells; (ii) that dCyd kinase mRNA levels were more sensitive in lower levels of 10 amol/micrograms of total RNA; and (iii) in cytosine arabinoside (ara-C)-resistant cells, both dCyd kinase mRNA levels and intracellular ara-CTP levels were lower compared with levels in sensitive cells. The PCR assay for dCyd kinase mRNA could be useful in the selection and monitoring of patients treated with nucleosides that are activated by this enzyme.

Acute Disease↗
PubMed1996

Non-radioactive assay of natural killer cell-mediated cytotoxicity against cytomegalovirus-infected fibroblasts by DNA fragmentation ELISA.

Cell-mediated cytotoxicity against cytomegalovirus (CMV)-infected fibroblasts (FS-4 cells) was investigated by a non-radioactive assay, and by DNA fragmentation ELISA and LDH release assay and the assays were compared to the standard chromium release assay. Fragmentation of DNA and LDH activity were detected in the supernatant of CMV-infected FS-4 cells cultured with non-adherent peripheral blood mononuclear cells (PBMC). The DNA fragmentation ELISA was most sensitive to cytotoxicity against CMV-infected FS-4 cells and showed excellent correlation with the standard chromium release assay. DNA fragmentation of CMV-infected FS-4 cells by non-adherent PBMC was reduced markedly by treatment with anti-leu 11b plus complement. Thus, the present DNA fragmentation ELISA is non-radioactive, highly sensitive and a useful method for detecting natural killer cell-mediated cytotoxicity against CMV-infected fibroblasts.

Adult↗
PubMed1996

Phase I/II study of combination chemotherapy with cisplatin, carboplatin and etoposide in small cell lung cancer.

A Phase I/II study of combination chemotherapy with cisplatin (CDDP), carboplatin (CBDCA) and etoposide (VP-16) (CPVP) was conducted in patients with small cell lung cancer. The dose level of etoposide was fixed at 100 mg/m2, while the doses of CDDP and CBDCA administered at each of the four steps were 50/200, 60/200, 60/250 and 70/250 mg/m2, respectively. Nine patients were allocated to each step dose group. Adverse effects were evaluated during the first two courses to establish the maximum tolerated dose (MTD). As a result, the step 3 doses turned out to be the MTD. The dose-limiting factor was hematotoxicity. Gastrointestinal toxicity was also present, but was tolerated. The overall response rate in patients with measurable or evaluable lesions was 91%. In 22 chemotherapy-naive patients, the median survival time was 16.6 months. These results suggest that the recommended dose is step 2, and that the CPVP regimen might be both more tolerable and more effective than the standard PVP regimen. Based on the above findings, CPVP therapy warrants further study in Phase II and III trials.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Effects of a newly developed transdermal clonidine delivery system (M-5041T) on EEG sleep-wake cycle in relation to plasma concentration in rabbits.

1. The effects of a transdermal clonidine delivery system (M-5041T) on EEG sleep pattern with relation to plasma concentrations in unrestrained rabbits were investigated and compared with those of intravenous (i.v.) administration of clonidine. 2. Although M-5041T did not affect the EEG recorded from cortex and hippocampus at doses up to 2.5 mg/kg, slow theta waves in hippocampal EEG accompanied by low-voltage slow waves in cortex were induced at a higher dose of 12.5 mg/kg. On i.v. injection (0.25 mg/kg), EEG tracings with bursts of high-voltage slow waves in cortical EEG and slow theta waves in hippocampus were observed. 3. At doses of 0.5 and 2.5 mg/kg, M-5041T did not cause any alterations of the sleep-wake cycle, and plasma concentrations of 1-2 ng/ml were maintained for an 8-hr observation period. However, this delivery system significantly suppressed the incidence of rapid-eye movement sleep (REMS) from 11.9 to 4.7% and enhanced drowsiness (DW) from 9.0 to 21.0% during the 8-hr recording period at 12.5 mg/kg with a plasma concentration of up to 10 ng/ml. Contrary to transdermal administration, i.v. clonidine (0.25 mg/kg) completely blocked light and deep slow wave sleep as well as REMS with a plasma concentration indicated more than 10 ng/ml at 2 hr post administration. Recovery to a normal sleep-wake cycle was eventually established thereafter. The incidence of REMS and DW were significantly decreased from 11.9 to 6.3% and increased from 9.0 to 25.5%, respectively. 4. Concurrent monitoring of clonidine concentrations in cerebrospinal fluid (CSF) indicated that CSF concentrations after patching M-5041T, as well as i.v. clonidine, were almost equal to plasma levels. 5. These results suggest that alteration of the sleep-wake cycle with clonidine occurs depending upon brain concentrations, which increase to a level similar to that in plasma after administration, and that M-5041T at doses of less than 2.5 mg/kg could establish effective hypertensive therapy without obvious effects on the cycle.

Animals↗
PubMed1996

Improved therapy for children with acute lymphoblastic leukemia.

We have examined the factors influencing clinical prognosis in Japanese children with B-precursor acute lymphoblastic leukemia (ALL), who have been treated in consecutive chemotherapeutic trials from 1976 to 1995. During this time the results of treatment have steadily improved in children with average presenting features (age 1-10 years old and leukocyte counts > 50,000/microL). The 4-year event-free survival (EFS) estimates now exceed 85% in our current trials. Furthermore, high-dose methotrexate and intrathecal therapy could be substituted for cranial irradiation without an increase of central nervous system relapse rate. However, children with unfavorable presenting features (leukocyte counts > or = 50,000/microL; high-risk group) have a worse prognosis, although there is some improvement of outcome. The patients in the high-risk group have obtained the 4-year EFS rate of better than 60%. Further investigations of prognostic factors in ALL focused on the biological features may permit identification of groups of children at risk of very poor outcome. In the patient cohorts consistently resistant to chemotherapy, the hazards of more intensive treatment such as bone marrow transplantation may be outweighed by the possible benefits.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Detection by polymerase chain reaction of wild-type measles virus genome in the cerebrospinal fluid of a patient with SSPE who had received measles vaccine.

BACKGROUND: Previous studies have reported that approximately 4-5% of patients with subacute sclerosing panencephalitis (SSPE) were given measles vaccination but had no history of natural measles. However, in the case who received measles vaccine, it has been extremely difficult to determine whether the actual cause of SSPE is the inoculated vaccine virus or not. OBJECTIVES: To detect the measles virus genome in a patient with SSPE and to analyze its nucleotide and deduced amino acid sequence. STUDY DESIGN: We applied the polymerase chain reaction (PCR) to detect the measles virus genome in specimens from a 12-year-old boy with SSPE who had received measles vaccine 10 years before and had no history of apparent natural measles. The oligonucleotide primers for PCR were prepared based on the nucleotide sequence of the F and NP genes of the measles virus Edmonston strain. RESULTS: F and NP genes were detected in both the cerebrospinal fluid and peripheral blood lymphocytes. Nucleotide and deduced amino acid sequence analysis of the F gene showed that the patient's virus was different from that of the vaccine strain. Judging from these results, it was likely that the SSPE-associated strain in this case was derived from the wild-type rather than the vaccine strain. CONCLUSIONS: PCR is a useful method to establish a definitive diagnosis of SSPE and to study the nature of the SSPE-associated virus.

Journal Article↗
PubMed1996

Structure-activity relationships of HIV-1 PR inhibitors containing AHPBA--II. Modification of pyrrolidine ring at P1' proline.

Systematic replacement in the 3- or 4-position of the pyrrolidine ring at P1' proline was carried out. Compound 26, which has a Cl atom in the 4(S)-position was the most active among inhibitors substituted with other halogen atoms or other substituents. Furthermore, the replacement of the Z group in compound 26 with five- or six-membered fused aromatic heterocycle carbonyl groups produced more potent inhibitors. 7-Methoxybenzofuran-2-carbonyl derivative (44) was the best of these and showed Ki = 4.5 nM against HIV PR and IC90S 0.58 microM and 0.06 microM in chronic and acute infections, respectively. These results suggest that the combination of the 4(S)-CI atom and fused bicyclic heterocycles may be effective in improving their cellular penetration.

Cells, Cultured↗
PubMed1996

Mite-specific induction of interleukin-2 receptor on T lymphocytes from children with mite-sensitive asthma: modified immune response with immunotherapy.

BACKGROUND: The efficacy of immunotherapy is still controversial. To elucidate the mechanisms of immunotherapy, we studied mite-specific induction of IL-2 receptor (IL-2R) expression on T lymphocytes from children with mite-sensitive asthma. METHODS: Peripheral blood mononuclear cells were obtained from 28 children with mite-sensitive asthma: 13 had never received house dust immunotherapy (nonimmunotherapy group), 15 had been receiving house dust immunotherapy at the time of the study (immunotherapy group). After a 6-day culture with or without Dermatophagoides farinae (Df) antigen, the expression of IL-2Rp55 (CD25) and p75 on CD4+ or CD8+ T lymphocytes was measured by flow cytometry. RESULTS: The nonimmunotherapy group showed significant Df-specific CD25 induction on CD4+ T lymphocytes (delta CD4+ CD25+) but little induction on CD8+ T lymphocytes (delta CD8+ CD25+). delta CD4+ CD25+ was correlated with the severity of the disease. In the immunotherapy group delta CD8+ CD25+ was significantly higher than in the nonimmunotherapy group or in normal subjects and correlated with Df-specific IgG4 and cumulative doses of house dust extract, whereas delta CD4+ CD25+ was similar in the nonimmunotherapy and the immunotherapy groups. IL-2Rp75 was not induced either on CD4+ or CD8+ T lymphocytes. CONCLUSIONS: Our data suggest that house dust immunotherapy may have induced Df-specific CD8+ T lymphocytes in patients with mite-sensitive asthma and that the efficacy of immunotherapy may be attributed to the generation of Df-specific CD8+ T lymphocytes.

Adolescent↗