Biomedical subjects

D Kobayashi

Publications and source records attributed to D Kobayashi.

95 records · Page 6Linked to original sources

PubMedDate not supplied

Endogenous tumour necrosis factor regulates heat-inducible heat shock protein 72 synthesis.

Endogenous tumour necrosis factor (enTNF) acts as a resistant factor against cytotoxicity of heat by induction of manganous superoxide dismutase (MnSOD), thereby scavenging reactive oxygen free radicals. On the other hand, it is also well known that heat shock proteins (HSPs), which are induced by heat-stress, behave as cytoprotecting factor against this stress. However, the relationship of these two resistant factors is not yet elucidated. In the present study we would therefore propose the possibility that enTNF enhances HSP72 expression. Heat-sensitive L-M (mouse tomourigenic fibroblast) cells, which normally do not express enTNF, were transfected with a nonsecretory-type human TNF expression vector to produce enTNF. Stable transfectants showed resistance to heat treatment and an increase of HSP72 expression. Conversely, when HeLa (human uterine cervical cancer) cells, which normally produce an appreciable amount of enTNF, were transfected with an antisense TNF mRNA expression vector to inhibit enTNF synthesis, their heat sensitivity was enhanced and HSP72 expression was reduced by half. In conclusion, these findings indicate that enTNF regulates heat-inducible HSP72 synthesis.

Animals↗

PubMedDate not supplied

Telomerase activity is down regulated via decreases in hTERT mRNA but not TEP1 mRNA or hTERC during the differentiation of leukemic cells.

BACKGROUND: Recent studies have determined several telomerase-associated molecules, but the precise mechanisms regulating telomerase activity by those molecules has not been fully understood. MATERIALS AND METHODS: The telomerase activity was determined by TRAP assay. Using TaqMan RT-PCR, the quantitative and kinetic values of mRNA expression of the three telomerase-associated molecules were examined in HL60 cells differentiated with tumor necrosis factor mutant and all-transretinoic acid. RESULTS: The levels of telomerase activity in leukemic cell lines, leukemic cells from patients, and normal peripheral blood cells were distributed over a very wide range. Human telomerase catalytic subunit (hTERT) mRNA expression declined to nearly undetectable levels more rapidly than the inhibition of telomerase activity after treatment with these reagents in HL60 cells. Telomerase-associated protein (TEP1) mRNA increased approximately 6-fold over its level in untreated cells. The levels of human telomerase RNA component (hTERC) also increased approximately 2.7-fold at 5 days after treatment. CONCLUSIONS: These results suggest that telomerase activity is down-regulated mainly via decreases in hTERT, but not TEP1 and hTERC expression during the differentiation of leukemic cells.

Adolescent↗

PubMedDate not supplied

Quantitative analysis of the anti-apoptotic gene survivin expression in malignant haematopoietic cells.

BACKGROUND: In this study we investigated expression profiles of the anti-apoptotic gene survivin in malignant human haematopoietic cells. MATERIALS AND METHODS: Using a quantitative TaqMan reverse transcription-polymerase chain reaction, survivin and bcl-2 mRNA expression were examined in 12 malignant haematopoietic cell lines, in 21 patients with haematopoietic malignancies and in normal leukocyte fractions. RESULTS: Survivin mRNA levels, demonstrable in all 12 malignant cell lines, differed but showed no relationship to the cell of origin. Conversely, no survivin mRNA expression was detected in normal leukocyte fractions. Further, survivin mRNA was expressed in 16 out of 21 patients with malignancies. Five days after treatment of HL-60 cells with a combination of all-trans retinoic acid and tumor necrosis factor, survivin expression decreased to 14.1% of that in untreated cells. Further, survivin mRNA expression in K-562/ADR cells with acquired resistance to adriamycin was 1.7 times that in parent K-562 cells. CONCLUSION: Our results indicated the possibility that quantitation of survivin mRNA expression is a useful tool for the detection of haematopoietic tumor cells in clinical laboratory test and that survivin could be a target for treatment of haematopoietic malignancies.

Adolescent↗

PubMedDate not supplied

Hematopoietic progenitor cell counts performed by the Sysmex SE-9000 analyzer can guide timing of peripheral blood stem cell harvest.

BACKGROUND: We studied whether the hematopoietic progenitor cell (HPC) count in peripheral blood as evaluated by an automated counter, the Sysmex SE-9000, correlated with CD34 positive (+) cell count and therefore could guide the timing of peripheral blood stem cell (PBSC) harvest. MATERIALS AND METHODS: HPC count and flow cytometric CD34+ cell count were measured in 90 peripheral blood samples and 30PBSC samples. The correlation between HPC count and apheretic CD34+ cell yield was examined in 19 patients. RESULTS: HPC count showed good correlations with CD34+ cell count in peripheral blood (r = 0.699) and PBSC (r = 0.892). The correlation between peripheral blood HPC count and apheretic CD34+ cell yield also was good (r = 0.789). CONCLUSION: Automated HPC counting can be used as a screening test to guide the timing of PBSC harvest.

Adult↗

PubMedDate not supplied

Quantitation of multiple myeloma oncogene 1/interferon-regulatory factor 4 gene expression in malignant B-cell proliferations and normal leukocytes.

BACKGROUND: We studied multiple myeloma oncogene 1/interferon-regulatory factor 4 (MUM1/IRF4) mRNA expression in various malignant human hematopoietic cell lines and normal leukocyte fractions. MATERIALS AND METHODS: A quantitative reverse transcription-polymerase chain reaction was used to assess expression and chromosomes were examined for anomalies by fluorescent in situ hybridization. RESULTS: Among 12 cell lines examined, mRNA transcripts were expressed only in B-lymphoblastic and myeloma cell lines. Myeloma cells and malignant cell lines derived from mature B cells expressed more transcript than cell lines derived from immature B cells. Transcript levels, however, showed no association with chromosomal translocations. Expression in B-cell fractions from healthy donors was much less than in the malignant cells. In addition, MUM1/IRF4 mRNA expressed in samples from patients with acute lymphoblastic leukemia derived from B cells but not T cells. CONCLUSION: Our results suggested that MUM1/IRF4 gene expression is related to stage of differentiation of malignant B cells and they indicated the possibility that the quantitative analysis of MUM1/IRF4 gene is a useful tool for detection of malignant B-cell proliferations in clinical laboratory tests.

Adolescent↗