Biomedical subjects

Hideki Harada

Publications and source records attributed to Hideki Harada.

42 records · Page 3Linked to original sources

PubMed2002

Pelotomaculum thermopropionicum gen. nov., sp. nov., an anaerobic, thermophilic, syntrophic propionate-oxidizing bacterium.

An anaerobic, thermophilic, syntrophic propionate-oxidizing bacterium, strain SI(T), isolated previously from granular sludge in a thermophilic upflow anaerobic sludge blanket (UASB) reactor, was characterized. The strain could grow fermentatively on pyruvate and fumarate in pure culture. The strain grew on propionate, ethanol, lactate, 1-butanol, 1-pentanol, 1,3-propanediol, 1-propanol and ethylene glycol in co-culture with the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus strain deltaH(T). The optimum temperature for growth was 55 degrees C and the pH optimum was 7.0. The G+C content of the DNA was 52.8 mol %. Strain SI(T) contained MK-7 and MK-7(H4) as the major quinones and contained iso-C15:0 as the major fatty acid. Based on 16S rDNA sequence analysis, strain SI(T) formed a novel lineage within the gram-positive, spore-forming, sulphate-reducing bacterial group Desulfotomaculum. However, the strain lacked the ability to conduct dissimilatory sulphate reduction. Instead, it could reduce fumarate to succinate with concomitant growth on several organic substances as electron donor. These phenotypic and genetic properties support the formation of a novel species of a new genus, for which the name Pelotomaculum thermopropionicum gen. nov., sp. nov. is proposed. The type strain is strain SI(T) (= DSM 13744T = JCM 10971T).

Base Composition↗

PubMed2002

Selective expansion of human natural killer cells from peripheral blood mononuclear cells by the cell line, HFWT.

An anchorage-dependent Wilms tumor cell line HFWT was found to stimulate selective and remarkable expansion of human natural killer (NK) cells from human peripheral blood mononuclear cells (PBMC). After PBMC of healthy donors were cultured on irradiated HFWT cells for 10 - 21 days, the lymphocytes expanded 58- to 401-fold. This NK cell expansion required direct contact of PBMC with live, but not fixed, HFWT cells. The PBMC from an end-stage brain tumor patient also expanded 156-fold, whereas those cultured with irradiated NK-sensitive K562 grew only 30.5-fold. CD16+ CD56+ NK cells accounted for more than 70% of the population expanded on HFWT cells. No essential difference in expression of NK receptors was observed in the expanded NK cells on HFWT and K562 and without feeder cells. The expanded NK cells killed not only fresh HFWT cells but, unexpectedly, also MHC class I-expressing autologous brain tumor cells at an effector/target ratio of 4 for 24 h. These results will contribute to the development of a large-scale preparation method for human NK cells, which will aid studies of NK cell biology and possible treatment of brain tumors.

Animals↗

PubMed2002

A mouse model of human oral-esophageal cancer.

Squamous cancers of the oral cavity and esophagus are common worldwide, but no good genetically based animal model exists. A number of environmental factors as well as genetic alterations have been identified in these cancers, yet the specific combination of genetic events required for cancer progression remains unknown. The Epstein-Barr virus ED-L2 promoter (L2) can be used to target genes in a specific fashion to the oral-esophageal squamous epithelium. To that end, we generated L2-cyclin D1 (L2D1(+)) mice and crossbred these with p53-deficient mice. Whereas L2D1(+) mice exhibit a histologic phenotype of oral-esophageal dysplasia, the combination of cyclin D1 expression and p53 deficiency results in invasive oral-esophageal cancer. The development of the precancerous lesions was significantly reversed by the application of sulindac in the drinking water of the L2D1(+)/p53(+/-) mice. Furthermore, cell lines derived from oral epithelia of L2D1(+)/p53(+/-) and L2D1(+)/p53(-/-) mice, but not control mice, formed tumors in athymic nude mice. These data demonstrate that L2D1(+)/p53(+/-) mice provide a well-defined, novel, and faithful model of oral-esophageal cancer, which allows for the testing of novel chemopreventive, diagnostic, and therapeutic approaches.

Animals↗

PubMed1998

Phylogenetic diversity of mesophilic and thermophilic granular sludges determined by 16S rRNA gene analysis.

The microbial diversity of two types of methanogenic granular sludge, mesophilic (35 degrees C) and thermophilic (55 degrees C), which had been treating sucrose/propionate/acetate-based artificial wastewater were compared. 16S rDNA clone libraries were constructed by PCR with a prokaryote-specific primer set, and partial sequencing of the clonal 16S rDNAs was conducted for phylogenetic analysis. Of 115 mesophilic granule and 110 thermophilic granule clones sequenced, 19 and 22%, respectively, were phylogenetically affiliated with the domain Archaea, and the remainder in each case were assigned to the domain Bacteria. Within the domain Archaea, the 16S rDNA clones in both libraries showed relatively close relationships with those of methanogens. Within the Bacteria, a major group represented in the mesophilic clone library was the delta subclass of the Proteobacteria (27%), in which high degrees of relatedness were observed between the clonal 16S rDNA sequences and those of previously identified syntrophic bacteria and sulfate-reducing bacteria. In contrast, in the thermophilic clone library, the Thermodesulfovibrio group (19%), the green non-sulfur bacteria (18%) and the low G + C subclass of the Gram-positive bacteria (18%) were predominant. A significant difference between the two libraries was that no clone affiliated with the Proteobacteria was detected in the thermophilic clone library, whereas the Proteobacteria was detected in the thermophilic clone library, whereas the Proteobacteria was the most predominant group in the mesophilic clones. Thirty-six and 24 different sequences were found in the mesophilic and thermophilic clones, respectively, suggesting that the microbial diversity of the thermophilic granule was lower than that of the mesophilic granule.

Archaea↗

PubMedDate not supplied

Antitumor activity of palmitic acid found as a selective cytotoxic substance in a marine red alga.

In a previous report, we discussed an extract from a marine red alga, Amphiroa zonata, which shows selective cytotoxic activity to human leukemic cells, but no cytotoxicity to normal human dermal fibroblast (HDF) cells in vitro. In this study, we identified palmitic acid, a selective cytotoxic substance from the marine algal extract, and investigated its biological activities. At concentrations ranging from 12.5 to 50 micrograms/ml, palmitic acid shows selective cytotoxicity to human leukemic cells, but no cytotoxicity to normal HDF cells. Furthermore, palmitic acid induces apoptosis in the human leukemic cell line MOLT-4 at 50 micrograms/ml. Palmitic acid also shows in vivo antitumor activity in mice. One molecular target of palmitic acid in tumor cells is DNA topoisomerase I, however, interestingly, it does not affect DNA topoisomerase II, suggesting that palmitic acid may be a lead compound of anticancer drugs.

Animals↗

PubMedDate not supplied

Autologous natural killer cell therapy for human recurrent malignant glioma.

BACKGROUND: Natural killer (NK) cells are highly efficient in the cellular immune response against malignant tumors without restriction of major histocompatibility complex. However clinical studies using autologous NK cells have been reported in only a very limited number of cases, due to the fact that selective NK expansion is difficult to achieve in this patient population. Here, we report the results of adoptive immunotherapy in patients with recurrent malignant gliomas using autologous NK cells that were expanded ex vivo by a novel method. PATIENTS AND METHODS: Peripheral blood mononuclear cells (PBMCs) were prepared from patients with malignant gliomas, and were co-cultured with an irradiated human feeder cell line (HFWT) in RHAM-alpha medium supplemented with 5% autologous plasma and interleukin-2. The resulting NK cell-rich effector cells were injected into 9 patients (16 courses) with recurrent malignant glioma (6 cases of WHO grade-3 glioma and 3 cases of grade-4 glioma). RESULTS: The mean frequency of NK cells among lymphocytes was 82.2 +/- 10.5%. A combination of focal and intravenous injections was peformed in 10 courses. Intravenous injection alone was performed in 6 courses. Further, intravenous injection of low-dose interferon beta (6x10(6) IU/week) was performed as an adjuvant therapy in all courses to achieve maximum benefit for enrolled patients. Clinical evaluation demonstrated 3 PR, 2 MR, 4 NC and 7 PD in a total of 16 courses of treatment. Severe neurological toxicity was not observed in any of the patients. CONCLUSION: It was demonstrated that NK cell-rich effector cells were expanded ex vivo from PBMCs in all nine cases of recurrent malignant glioma and that NK cell therapy was safe and partially effective in patients with recurrent malignant gliomas.

Adult↗