Biomedical subjects

H Ikeda

Publications and source records attributed to H Ikeda.

At least 559 records · Page 31Linked to original sources

PubMed1996

Isolation and sequence determination of cDNA encoding mouse rab 4 and candidate approach for the beige mutation in mice.

The Chediak-Higashi syndrome is characterized by partial albinism and recurrent infections with giant granules in granulocytes. This syndrome has been proposed to have a defect in vesicular transport. Rab 4 is a member of a family of Ras-related small GTP-binding proteins, which has been mapped in the locus of the Chediak-Higashi syndrome. We isolated a full length cDNA of rab 4 from a cDNA library of mouse liver. The clone is 1428 base pairs (bp) in length and contains a 639 bp open reading frame encoding a polypeptide of 213 residues. The deduced amino acid sequence is highly homologous to rab 4 from rat and human. We analyzed rab 4 as a candidate gene of the beige mouse, but we could not find any change in the sequence of the coding region of rab 4 mRNA.

Amino Acid Sequence↗

PubMed1996

Effects of mutations of RAD50, RAD51, RAD52, and related genes on illegitimate recombination in Saccharomyces cerevisiae.

To examine the mechanism of illegitimate recombination in Saccharomyces cerevisiae, we have developed a plasmid system for quantitative analysis of deletion formation. A can1 cyh2 cell carrying two negative selection markers, the CAN1 and CYH2 genes, on a YCp plasmid is sensitive to canavanine and cycloheximide, but the cell becomes resistant to both drugs when the plasmid has a deletion over the CAN1 and CYH2 genes. Structural analysis of the recombinant plasmids obtained from the resistant cells showed that the plasmids had deletions at various sites of the CAN1-CYH2 region and there were only short regions of homology (1-5 bp) at the recombination junctions. The results indicated that the deletion detected in this system were formed by illegitimate recombination. Study on the effect of several rad mutations showed that the recombination rate was reduced by 30-, 10-, 10-, and 10-fold in the rad52, rad50, mre11, and xrs2 mutants, respectively, while in the rad51, 54, 55, and 57 mutants, the rate was comparable to that in the wild-type strain. The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination.

Adenosine Triphosphatases↗

PubMed1996

Human T lymphocyte virus type I-induced myeloneuropathy in rats: implication of local activation of the pX and tumor necrosis factor-alpha genes in pathogenesis.

The pathogenetic roles of human T lymphocyte virus type I (HTLV-I) and cytokines were investigated in HTLV-I-induced myeloneuropathy in Wistar-King-Aptekman-Hokudai rats. In the nervous system, pX messenger RNAs of HTLV-I were selectively expressed in the diseased spinal cord and peripheral nerves but not in the unaffected cerebrum and cerebellum, even though proviral DNAs were consistently identified in these tissues. Among several cytokines examined, mRNA expression and production of tumor necrosis factor (TNF)-alpha in the spinal cord and cerebrospinal fluid correlated positively with the development of spinal cord lesions. The collective evidence strongly suggests that selective activation of HTLV-I, in particular Tax expression and production of TNF-alpha induced by HTLV-I infection in target spinal cord and peripheral nerves, is causally related to apoptotic death of oligodendrocytes and Schwann cells, a major pathogenetic pathway of the HTLV-I-induced myeloneuropathy.

Animals↗

PubMed1996

Clonal dominance of human autologous cytotoxic T lymphocytes against gastric carcinoma: molecular stability of the CDR3 structure of the TCR alphabeta gene.

In our previous study, RT-PCR suggested that cytotoxic T lymphocyte (CTL) clones may specifically recognize human autologous gastric signet ring cell tumor (HST2) by using TCR products of Valpha7 and Vbeta20 subfamilies. In this report, we first determined the TCR nucleotide sequences of one such CTL from patient's peripheral blood lymphocytes (PBL), the PBL were newly stimulated with a mixed lymphocyte-autologus tumor cell (HST2) culture (MLTC) and cytotoxic T cell lines, such as HPBL3x, were obtained. RT-PCR and the nucleotide sequence data indicated that HPBL3x also showed TCR Valpha7 and Vbeta transcripts, and that HPBL3x TCR was composed of the exact same CDR3 gene structures as those of the TcHLT2 clone. T cells with same TCR structures were also detected in patient's non-treated peripheral blood, although they were infrequent. These data indicated that functional cytotoxic T cells with these distinct CDR3 equivalent structures were the dominant effector cells against HST2 autologous tumor cells. Moreover, the highly dominant and reproducible clonal expansion of T cells bearing heterodimeric TCR with identical variable, N diversity and constant region structures suggest that the molecular nature of governing antigenic peptide to TcHDT2 may be stable and perhaps immunologically dominant in the interaction between CTL and HST2 autologous tumor cells.

Amino Acid Sequence↗

PubMed1996

Treatment of whole houses with liquid nitrogen for control of dust mites.

A large volume of liquid nitrogen, (120-150 L) was applied to the houses of 4 asthmatic patients, and the mite densities of the floor dust from these houses were monitored every 2 wk for 4 mo from July to November 1989. The 1st liquid nitrogen treatment was applied in early August and decreased the mite densities to 20-44% of the pretreatment level in all cases, but they returned to the pretreatment level 3-4 wk later (on 3 occasions). The 2nd liquid nitrogen treatment was applied in early September and decreased the mite densities to 6-27% of the pretreatment level within 3 wk in all cases. However, mite numbers again increased to the pretreatment level 4 wk after treatment. The 3rd treatment was applied in mid-October and reduced the mite densities to < 6% of the pretreatment level within 2 wk, and mite numbers remained low thereafter. The results suggested that using liquid nitrogen to freeze houses reduces mite numbers, but that mite recolonization of the houses is an important problem.

Animals↗

PubMed1996

Soybean protein suppresses hepatic lipogenic enzyme gene expression in Wistar fatty rats.

The effects of dietary soybean protein on lipogenic enzyme gene expression in livers of genetically fatty rats (Wistar fatty) have been investigated. When Wistar fatty rats and their lean littermates (7-8-wk old) were fed a casein or soybean protein isolate diet containing hydrogenated fat (4% hydrogenated fat plus 1% corn oil) or corn oil (5%) for 3 wk, the hepatic messenger RNA concentrations and activities of lipogenic enzymes were significantly lower in rats fed soybean protein than in those fed casein, regardless of genotype or dietary fat. The conversion rates of thyroxine to triiodothyronine by liver microsomes and plasma triiodothyronine concentrations were lower in the fatty rats than in the lean rats and were significantly greater in rats fed soybean protein than in those fed casein. Conversely, plasma and liver triacylglycerol concentrations were lower in soybean protein-fed fatty and lean rats than in those fed casein. The body weight was less in the fatty rats fed soybean protein than in those fed casein after 3 wk of feeding. Moreover, dietary polyunsaturated fatty acids suppressed lipogenic enzyme gene expression in the lean rats but did not in the fatty rats. Dietary soybean protein appeared to be useful for the reduction of obesity.

ATP Citrate (pro-S)-Lyase↗

PubMed1996

Prognostic factors and a predictive model of follicular lymphoma: a 25-year study at a single institution in Japan.

The incidence of follicular lymphoma in Japan is far lower than that in western countries, and no large-scale clinicopathologic studies on this neoplasm have been conducted in Japan. We reviewed histopathological specimens from 118 of 135 patients who had been diagnosed as having follicular lymphoma between 1968 and 1993. Prognostic factors influencing survival were analyzed using univariate and multivariate analyses. Factors that were independently significant upon multivariate analysis were incorporated into a predictive model. Ninety-three patients (78.8%) had a confirmed diagnosis of follicular lymphoma. Twenty-one of the remaining 25 patients were categorized as having other lymphoma subtypes, and four patients showed indefinite findings or those suggesting diseases other than lymphoma. Major characteristics of the 93 patients with follicular lymphoma were a median age of 53 years (20-85); 59 males (63%) and 34 females (37%); small cleaved cell type in 33 (35%), mixed cell type in 41 (44%) and large cell type in 19 (20%); stage I/II in 41 (44%) and stage III/IV in 50 (54%). Overall survival was 71% at 5 years, 58% at 10 years, and 43% at 15 years with a median survival of 13.3 years. Multivariate analysis revealed that two variables, age (>60) (P=0.001) and the serum LDH level (>1 x normal value) (P=0.026), were unfavorably significant prognostic factors influencing survival. The predictive model using these two variables identified three risk groups with estimated five-year survival rates of 88.5%, 56.8%, and 31.5%. Age and serum LDH were significant predictors of survival in Japanese patients with follicular lymphoma. Our predictive model may provide a basis for future therapeutic trials against follicular lymphoma in Japan.

Adult↗

PubMed1996

Massive apoptosis detected by in situ DNA nick end labeling in neuroblastoma.

To seek evidence that tumor regression in neuroblastoma might result from massive apoptosis, we investigated tumor cell death in 39 neuroblastomas. Characteristic histologic features of apoptosis, condensed nuclear fragments and eosinophilic cytoplasm, were observed in all specimens. A ladder of DNA fragments induced by apoptosis was demonstrated by means of DNA agarose gel electrophoresis in 18 of the 19 tumors examined. In situ DNA nick end labeling (TUNEL) stained the nuclei with DNA fragmentation in 16 of 39 neuroblastomas. The TUNEL -positive cells were distributed in a scattered fashion in 10 tumors. In the remaining six tumors, they were densely located around nonviable areas of calcifications, where karyorrhectic or pyknotic cells were frequently observed. Five of six patients with such tumors were under 12 months of age, but there was no significant difference between the two groups in the patient age, origin of the primary lesion, or tumor stage. Biological features, including histology. DNA ploidy, and N-myc amplification, were not significantly different . Double fluorescent staining for bcl-2 oncoprotein and TUNEL showed that bcl-2 oncoprotein was expressed in the cytoplasm of tumor cells that were negative for TUNEL staining. This accumulated evidence suggests that massive apoptosis of tumor cells occurs in some neuroblastomas and may be related to tumor regression, whereas inhibition of apoptosis by bcl-2 oncoprotein expression might be associated with the tumorigenesis of neuroblastomas, as reported in our previous study.

Adrenal Gland Neoplasms↗

PubMed1996

Establishment of a therapeutic model for retroviral infection using the genetic resistance mechanism of the host.

Resistance to retroviral infection is often regulated by multiple genes that control different aspects of the host-virus interaction. Genetically distinct inbred strains of mice differ in their susceptibility to retrovirus and have allowed the identification of several host-resistant loci that regulate the host defense mechanism to retroviral infection. Using the murine retrovirus infection system, a therapeutic model has been developed of retrovirus infection in association with the resistant mechanism of host genes. The most effective result achieved with the model was when using bone marrow transplantation of retrovirus-resistant cells with receptor interference function, which was genetically defined by the Fv-4 resistant gene. The possible application of these findings to the gene therapy of retrovirus-induced disease of humans is discussed.

Animals↗

PubMed1996

Platelet adenylyl cyclase activity in alcoholics and subtypes of alcoholics. WHO/ISBRA Study Clinical Centers.

Adenylyl cyclase (AC) activity was measured in membrane preparations of platelets from control and alcoholic subjects. The sample consisted of 51 alcoholics who were categorized as type I or type II using the criteria of Gilligan et al. (Genet. Epidemiol. 4:395-414, 1987) and 54 normal controls. Alcoholic males exhibited significantly lower values than controls in basal and fluoride-stimulated platelet AC activity. When male alcoholics were segregated into type I and type II categories, the platelet AC activity did not differ between subtypes, and both subtypes had AC activity that was below control values. Western blot analysis of the quantity of Gs alpha and Gi alpha proteins in a subset of male controls and alcoholic subjects demonstrated no significant relationship between quantity of G proteins and AC activity. The results confirm lower platelet AC activity in male alcoholics, compared with controls. Given the lack of quantitative relations between Gs alpha and Gi alpha proteins and AC activity, the results support the contention that individual differences in platelet AC activity in the alcoholic subjects may reflect quantitative or qualitative differences in the AC catalytic units.

Adenylyl Cyclases↗

PubMed1996

Quinolone-resistant mutants of escherichia coli DNA topoisomerase IV parC gene.

Escherichia coli quinolone-resistant strains with mutations of the parC gene, which codes for a subunit of topoisomerase IV, were isolated from a quinolone-resistant gyrA mutant of DNA gyrase. Quinolone-resistant parC mutants were also identified among the quinolone-resistant clinical strains. The parC mutants became susceptible to quinolones by introduction of a parC+ plasmid. Introduction of the multicopy plasmids carrying the quinolone-resistant parC mutant gene resulted in an increase in MICs of quinolones for the parC+ and quinolone-resistant gyrA strain. Nucleotide sequences of the quinolone-resistant parC mutant genes were determined, and missense mutations at position Gly-78, Ser-80, or Glu-84, corresponding to those in the quinolone-resistance-determining region of DNA gyrase, were identified. These results indicate that topoisomerase IV is a target of quinolones in E. coli and suggest that the susceptibility of E. coli cells to quinolones is determined by sensitivity of the targets, DNA gyrase and topoisomerase IV.

Anti-Infective Agents↗

PubMed1996

Role of the recJ gene product in UV-induced illegitimate recombination at the hotspot.

Illegitimate recombination between a prophage and adjacent bacterial DNA is the first step in the formation of specialized transducing phage. Such recombination is rare, but it is greatly enhanced by UV irradiation. We studied the mechanism of UV-induced illegitimate recombination by examining the effect of rec mutations on the frequency of lambda bio transducing phage and found that an Escherichia coli recJ mutation reduces it by 3- to 10-fold. In addition, the recombination hotspot, which accounts for approximately 60% of lambda bio transducing phages in wild-type bacteria, was not detected in the recJ mutant. Introduction of a RecJ overexpression plasmid into the recJ mutant recovered the recombination at the hotspot. These results indicate that the RecJ protein preferentially stimulates illegitimate recombination at the hotspot. Both the hotspot and the non- hotspot sites have short regions of homology, but only the hotspot sites contain common direct-repeat sequences. We propose a model based on the 5'-3' exonuclease activity of RecJ to explain the involvement of this protein in illegitimate recombination at the hotspot.

Bacterial Proteins↗

PubMed1996

Xanthine oxidase mediates cyclic flow variations in a canine model of coronary arterial thrombosis.

We investigated the hypothesis that xanthine oxidase (XO) mediates platelet aggregation and cyclic flow variations (CFVs) in stenosed canine coronary arteries. CFVs were produced by an external constrictor placed at the site of the coronary artery with the injured endothelium. The severity of CFVs was evaluated by a pulsed Doppler flow probe. If CFVs developed, dogs intravenously received allopurinol, a specific XO inhibitor. The transcardiac gradient (difference between coronary vein and left atrium) of purine metabolites was determined during CFVs and after allopurinol administration. Allopurinol significantly reduced CFVs (from 8 +/- 1 to 1 +/- 1 cycles/h, P < 0.01, n = 14), whereas saline did not (from 8 +/- 1 to 7 +/- 1 cycles/h, n = 7). In seven dogs with CFVs, the transcardiac gradient of xanthine and uric acid concentrations significantly increased after the establishment of CFVs and significantly decreased after the administration of allopurinol. In vitro platelet studies showed that XO enhanced (from 30.9 +/- 2.0 to 47.6 +/- 1.5%, P < 0.0001, n = 10) and allopurinol inhibited ADP-induced platelet aggregation (from 48.3 +/- 1.3 to 24.8 +/- 1.5%, P < 0.0001, n = 10). Our results indicate that allopurinol inhibits platelet aggregation in vitro and provides a protection against CFVs in vivo. Thus XO may be an important mediator in this model.

Allopurinol↗

PubMed1996

Increased secretion of triglyceride and cholesterol following inhibition of long-chain fatty acid oxidation in rat liver.

The effects of emeriamine, a fungal metabolite and a potent inhibitor of mitochondrial fatty acid oxidation, on ketogenesis and lipid secretion were examined in isolated perfused livers from 2-day-fasted rats. Liver perfusion with increasing concentrations of emeriamine up to 3 mumol caused a dose-dependent inhibition of ketone body production. The hepatic uptake of exogenous oleic acid substrate was comparable in the control and emeriamine-treated livers. The addition of 2 mumol emeriamine to the perfusion medium at either the beginning of perfusion or 2 h later caused immediate and almost complete cessation of ketone body production, which was accompanied by a concomitant decrease in the beta-hydroxybutyrate: acetoacetate ratio, suggesting a decreased production of NADH via mitochondrial beta-oxidation. Conversely, both triglyceride and cholesterol secretions were elevated, indicating a reciprocal response in ketogenesis and lipid secretion by the livers. The proportion of oleate in the perfusate triglyceride obtained from emeriamine-treated livers was significantly higher than that from control livers. In the post-perfused liver triglyceride, oleate was progressively increased in the livers treated with the inhibitor 2 h after perfusion and at the beginning of perfusion, respectively. These results indicate that direct inhibition of fatty acid oxidation diverts the exogenous fatty acids to the esterification pathway, and subsequently stimulate the synthesis and secretion of triglyceride and cholesterol. The fatty acid oxidation rate in the liver is, therefore, a critical determinant for the synthesis and secretion of these lipid components.

3-Hydroxybutyric Acid↗

PubMed1996

Selective loss of small myelinated fibers in the lateral corticospinal tract due to midbrain infarction.

Small myelinated fibers in the lateral corticospinal tract (LCST) were selectively diminished as compared with large myelinated fibers in a patient with an old paramedian midbrain infarct involving the red nuclei, oculomotor nuclei, and inferior olivary pseudohypertrophy. Although the physiologic function of small myelinated fibers in the LCST is unknown in humans, we hypothesize that some of these fibers may include the rubrospinal tract.

Cerebral Infarction↗

PubMed1996

The effects of thrombopoietin on the growth of acute myeloblastic leukemia cells.

Thrombopoietin (TPO) is a novel hematopoietic growth factor that was cloned as a ligand for c-mpl proto-oncogene. The c-mpl proto-oncogene is expressed on various types of human leukemia cell lines derived from erythroid, megakaryocytic, and stem-cell leukemia cells. Also, c-mpl mRNA is detectable on blast cells in about half of acute myeloblastic leukemia (AML) cases regardless of French-American-British (FAB) classification. In the cases with myelodysplastic syndrome, c-mpl is expressed in a substantial fraction of refractory anemia with excess of blast (RAEB), RAEB in transformation, and chronic myelomonocytic leukemia cells, but not in refractory anemia or sideroblastic anemia. Little or no expression of c-mpl mRNA is observed in human lymphoid cell lines and blast cells of acute lymphoblastic leukemia cases. The in vitro treatment of AML cells with TPO resulted in proliferation in about 70% of c-mpl-positive AML cases. The proliferative responses of AML cells to TPO were observed not only in M7-type, but also in the other subtypes of AML cases. Furthermore, the TPO-induced proliferation of AML cells was augmented by the addition of the other hematopoietic growth factors such as interleukin-3 (IL-3), IL-6, stem cell factor, or granulocyte-macrophage colony-stimulating factor. In addition to proliferation, TPO appeared to induce megakaryocytic differentiation in a small part of AML cells. These results suggested that TPO/c-mpl system might contribute, at least in part, to abnormal growth and differentiation of AML cells.

Cell Differentiation↗

PubMed1996

Coexpression of thrombopoietin and c-mpl genes in human acute myeloblastic leukemia cells.

Thrombopoietin (TPO) is a recently identified hematopoietic growth factor that is essential for the growth and development of megakaryocytes. We have previously shown that TPO induces proliferation of acute myeloblastic leukemia (AML) cells in vitro. In this study, we have examined the expression of TPO and its receptor c-mpl in a series of AML cases and human leukemia cell lines. The mRNA transcripts of TPO were detectable in 18 of 50 AML cases and in some myeloid leukemia cell lines (HEL, M07E and CMK) by means of reverse transcriptase polymerase chain reaction (RT-PCR). In addition, TPO transcripts were coexpressed with c-mpl transcripts in 10 of 50 AML cases and in HEL, M07E and CMK cells. With regard to the French-American-British (FAB) classification, coexpression OF TPO and c-mpl was observed with high frequency in AML cases of M7-type. Despite the TPO expression in a substantial fraction of leukemia cells, biological activity of TPO was not found in the conditioned medium that was obtained from cultivation of TPO mRNA-positive leukemia cells. These results suggest that TPO may not commonly participate in the abnormal growth of AML cells as an extracellular autocrine growth factor.

Base Sequence↗

PubMed1996

Late local recurrence after radiotherapy for tongue and early glottic carcinoma.

BACKGROUND/AIM: Late local recurrence after radiotherapy for tongue and early glottic carcinoma is rarely discussed. In the head and neck cancer, approximately 90% of local recurrence occurred within 2 years after radiotherapy. However, we found that late local recurrence after radiotherapy for glottic cancer was not rare. Our aim was to evaluate the late local recurrence after radiotherapy for early glottic and tongue cancer. PATIENTS AND METHODS: From 1967 through 1982, 633 patients with tongue carcinoma and 330 patients with early (T1T2N0) glottic carcinomas were treated at the Department of Radiology, Osaka University Hospital. Of these 821 patients, 329 patients with tongue carcinoma and 221 patients with early glottic carcinoma survived at 5 years after radiotherapy without local recurrence. For tongue carcinoma, patients were divided by T category. For early glottic carcinoma, patients were divided by the tumor response at 40 Gy. RESULTS: Late local recurrence occurred in 23 of 329 patients (7%) with tongue carcinoma, and in 9 of 221 (4%) with early glottic carcinoma. For tongue carcinoma, late recurrence occurred in 19 of 249 patients (8%) in stage I and II, and 4 of 80 patients (5%) in stage III and IV. For glottic carcinoma, late recurrence occurred in 8 of 137 patients (6%) with tumor clearance at 40 Gy and 1 of 63 patients (2%) with tumor persistence at 40 Gy. The incidence of double cancer was also evaluated. Of 329 5-year survivors with tongue carcinoma, 39 patients (12%) had another malignancy, and 26 patients of 221 5-year survivors with early glottic carcinoma (12%) had also another malignancy. Of 39 double primaries of tongue carcinoma, 10 patients (26%) had head and neck malignancies, and none of 26 double primaries of early glottic carcinoma. CONCLUSION: Late local recurrence was not rare in tongue and early glottic cancer. Poor prognostic group showed lower incidence of late recurrence than good prognostic group. This result suggests that secondary tumor at the same site of primary tumor is late local recurrence.

Carcinoma↗