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Biomedical subjects

H Tanaka

Publications and source records attributed to H Tanaka.

At least 181 records · Page 10Linked to original sources
PubMed2002

Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan.

Significant anomalous changes in the ultra low frequency range (approximately 0.01 Hz) were observed in both geoelectric and geomagnetic fields before the major volcano-seismic activity in the Izu Island region, Japan. The spectral intensity of the geoelectric potential difference between some electrodes on Niijima Island and the third principal component of geomagnetic field variations at an array network in Izu Peninsula started to increase from a few months before the onset of the volcano-seismic activity, culminating immediately before nearby magnitude 6 class earthquakes. Appearance of similar changes in two different measurements conducted at two far apart sites seems to provide information supporting the reality of preseismic electromagnetic signals.

Electricity↗
PubMed2002

Tuning of electronic structures of quasi-one-dimensional bromo-bridged Ni(III) complexes with strong electron-correlation by doping of Co(III) ions, [Ni(1-x)Co(x)(Chxn)(2)Br]Br(2).

We have succeeded in synthesizing the Ni(III) complexes doped by Co(III) ions, [Ni(1-x)Co(x)(chxn)(2)Br]Br(2) (x = 0, 0.043, 0.093, and 0.118) by using an electrochemical oxidation method. The single-crystal reflectance spectrum of x = 0.118 shows an intense CT band about 0.5 eV, which is lower than that of [Ni(chxn)(2)Br]Br(2) (1.3 eV). The single-crystal electrical conductivities at room temperature of these compounds increase with increase of the amounts of doping of Co(III) ions. In the ESR spectra, peak-to-peak line widths DeltaH(pp) at room temperature change about 600 G in [Ni(chxn)(2)Br]Br(2) to 200 G in x = 0.118. Such a large x dependence of DeltaH(pp) seems to be ascribed to the increasing contribution from the increasing Curie spins which have smaller line width. Therefore, we have tuned the electronic structures of quasi-one-dimensional bromo-bridged Ni(III) complexes with strong electron correlations by doping of Co(III) ions.

Journal Article↗
PubMed2002

Improvement of mass transfer characteristics and productivities of inclined tubular photobioreactors by installation of internal static mixers.

The feasibility of improving mass transfer characteristics of inclined tubular photobioreactors by installation of static mixers was investigated. The mass transfer characteristics of the tubular photobioreactor varied depending on the type (shape) and the number of static mixers. The volumetric oxygen transfer coefficient ( k(L)a) and gas hold up of the photobioreactor with internal static mixers were significantly higher than those of the photobioreactor without static mixers. The k(L)a and gas hold up increased with the number of static mixers but the mixing time became longer due to restricted liquid flow through the static mixers. By installing the static mixers, the liquid flow changed from plug flow to turbulent mixing so that cells were moved between the surface and bottom of the photobioreactor. In outdoor culture of Chlorella sorokiniana, the photobioreactor with static mixers gave higher biomass productivities irrespective of the standing biomass concentration and solar radiation. The effectiveness of the static mixers (average percentage increase in the productivities of the photobioreactor with static mixers over the productivities obtained without static mixers) was higher at higher standing biomass concentrations and on cloudy days (solar radiation below 6 MJ m(-2) day(-1)).

Absorption↗
PubMed2002

Metabolic response against sulfur-containing heterocyclic compounds by the lignin-degrading basidiomycete Coriolus versicolor.

The fungal conversions of sulfur-containing heterocyclic compounds were investigated using the lignin-degrading basidiomycete Coriolus versicolor. The fungus metabolized a series of sulfur compounds--25 structurally related thiophene derivatives--via several different pathways. Under primary metabolic conditions, C. versicolor utilized thiophenes, such as 2-hydroxymethyl-, 2-formyl-, and 2-carboxyl-thiophenes, as a nutrient sulfur source for growth; thus, the fungus degraded these compounds more effectively in a non-sulfur-containing medium than in conventional medium. The product analysis revealed that several redox reactions, decarboxylation reactions, and C-S cleavage reactions were involved in the fungal conversion of non-aromatic thiophenes. On the other hand, benzothiophene (BT) and dibenzothiophene (DBT) skeletons were converted to water-soluble products. All the products and metabolic intermediates were more hydrophilic than the starting substrates. These metabolic actions seemed to be a chemical stress response against exogenously added xenobiotics. These metabolic reactions were optimized under ligninolytic conditions, also suggesting the occurrence of a fungal xenobiotic response. Furthermore, the fungus converted a series of BTs and DBTs via several different pathways, which seemed to be controlled by the chemical structure of the substrates. DBT, 4-methylDBT, 4, 6-dimethylDBT, 2-methylBT, and 7-methylBT were immediately oxidized to their S-oxides. BTs and DBTs with the hydroxymethyl substituent were converted to their xylosides without S-oxidation. Those with carboxyl and formyl substituents were reduced to form a hydroxymethyl group, then xylosidated. These observations strongly suggested the involvement of a fungal substrate-recognition and metabolic response mechanism in the metabolism of sulfur-containing heterocyclic compounds by C. versicolor.

Benzaldehydes↗
PubMed2002

Interactions between photoautotrophic and heterotrophic metabolism in photoheterotrophic cultures of Euglena gracilis.

Interactions between photoautotrophic and heterotrophic metabolism in photoheterotrophic culture of Euglena gracilis were studied. Under a low light supply coefficient, these two metabolic activities seem to proceed independently. The cell growth rate in photoheterotrophic culture was about the sum of the growth rates in pure photoautotrophic and heterotrophic cultures. However under a high light supply coefficient, both photoautotrophic and heterotrophic (glucose assimilation) metabolic activities were inhibited, resulting in a low photoheterotrophic growth rate. The photoheterotrophic culture was more sensitive to photoinhibition compared to the pure photoautotrophic culture. Inhibition of glucose assimilation in the photoheterotrophic culture was due to both direct and indirect (through photosynthesis) effects of high light intensity. Cell growth, glucose assimilation and alpha-tocopherol content of the cells were higher when ambient air was used for aeration than when a mixture of carbon dioxide and air was used. Even when photosynthesis was inhibited by addition of 3-(3,4-dichlorophenyl)- 1,1-dimethylurea to photoheterotrophic culture, light stimulated alpha-tocopherol synthesis by E. gracilis.

Aerobiosis↗
PubMed2002

Time course study on the development of allergen-induced airway remodeling in mice: the effect of allergen avoidance on established airway remodeling.

OBJECTIVE AND DESIGN: We carried out a time course study on the development of allergen-induced airway remodeling in a mouse model of allergic asthma. Moreover, we examined the effect of allergen avoidance on the established airway remodeling. MATERIALS AND METHODS: BALB/c mice were sensitized to ovalbumin (OA) with alum, and exposed daily for 3 weeks to aerosolized OA. At each designated point, bronchial responsiveness was measured, and bronchoalveolar lavage and histological examination were carried out. RESULTS: The numbers of inflammatory leukocytes in the airways and the percentage of goblet cells in the epithelium, Th2 cytokine production, IgE production, collagen deposition beneath the basement membrane and bronchial responsiveness to acetylcholine were all markedly increased after repeated antigen challenge for 1-3 weeks. In contrast, after cessation of antigen exposure, goblet cell hyperplasia, inflammatory infiltrates and bronchial hyperresponsiveness were gradually attenuated and had almost resolved 4 weeks after cessation, but subepithelial fibrosis was still observed at this time point. CONCLUSIONS: The present findings demonstrated that epithelial changes following repeated allergen challenge are rapidly induced and recover after the cessation of exposure, but subepithelial fibrosis has a late onset and relatively irreversible changes, and subepithelial fibrosis in contrast to goblet cells hyperplasia did not appear to contribute to bronchial hyperresponsiveness, at least, in this mouse model.

Acetylcholine↗
PubMed2002

Identification and characterization of novel cytochrome P450 genes from the white-rot basidiomycete, Coriolus versicolor.

Using a reverse-transcription polymerase chain reaction (RT-PCR) technique, cytochrome P450 genes were cloned from the lignin-degrading basidiomycete, Coriolus versicolor. One possible P450 gene was identified, which consisted of 1,672 nucleotides and a poly(A) tail and encoded a deduced protein containing 449 amino acids. The deduced amino acid sequence revealed the presence of the P450 heme-binding motif, strongly suggesting that this protein belongs to the P450 superfamily, then designated CYP512A1. The deduced protein showed sequential similarity to other known P450s from several micro-organisms, such as Aspergillus terreus, Gibberella fujikuroi, and Neurospora crassa, with 30-35% identity. Since the identity of the amino id sequence was less than 40% with any other P450s, this protein was suggested to be the first member of a new family of cytochrome P450. In addition, a differential display RT-PCR analysis showed the expression of the other P450 genes, which were up-regulated by the addition of dibenzothiophene and 4-methyldibenzothiophene-5-oxide. Using the 5' rapid amplification of cDNA ends method, a 520-nucleotide sequence, including the P450 motif-coding region, was determined for one clone. The deduced protein showed high similarity to CYP512A1 but less than 40% identity with P450s from other organisms. A chemical stress-responsive expression of P450 is suggested for the first time in basidiomycetes.

Amino Acid Sequence↗
PubMed2002

Association of angiotensin-converting-enzyme gene polymorphism with the depressor response to mild exercise therapy in patients with mild to moderate essential hypertension.

We studied the association of angiotensin I-converting enzyme (ACE) gene polymorphism with the depressor response to exercise therapy in 64 Japanese subjects with mild to moderate essential hypertension. Each subject performed 10 weeks of mild (lactate threshold intensity: approximately 50% maximum oxygen consumption) exercise therapy on a bicycle ergometer. Systolic blood pressure (SPB), diastolic blood pressure (DPB), and mean arterial pressure (MAP) were significantly decreased by exercise therapy in subjects with the ACE-II and ID genotypes but not in DD subjects. The time-by-genotype interaction effects were significant for DBP and MAP. According to a multiple logistic regression analysis, the age- and baseline plasma renin activity-adjusted relative risk (odds ratio) for the lack of a depressor response conferred by the D allele (assuming an additive effect) was 2.72 [95% confidence interval (CI), 1.07-6.91; p = 0.034]; for DD genotypes, as compared with the DI and II genotypes (assuming that the D allele is recessive), it was 11.7 (95% CI, 2.25-60.6; p = 0.003). ACE gene I/D polymorphism is associated with the depressor response of essential hypertensives to mild exercise therapy, which suggests that genetic features may underlie, at least in part, the heterogeneity of the depressor response in essential hypertensives to mild exercise therapy.

Blood Pressure↗
PubMed2002

Transient hematopoietic stem cell rescue using umbilical cord blood for a lethally irradiated nuclear accident victim.

We performed stem cell rescue and allogeneic skin transplantation on a lethally neutron-irradiated nuclear accident victim. HLA-DRB1 mismatched unrelated umbilical cord blood cells (2.08 x 10(7)/kg recipient body weight) were transplanted to an 8-10 Gy equivalent neutron-irradiated patient because of a lack of a suitable bone marrow or peripheral blood donor. Pre-transplant conditioning consisted of anti-thymocyte gamma-globulin alone, and GVHD prophylaxis was a combination of cyclosporine (CYA) and methylprednisolone (mPSL). Granulocyte colony-stimulating factor (G-CSF), erythropoietin (EPO), and thrombopoietin (TPO) were concurrently administered after transplantation. The absolute neutrophil count reached 0.5 x 10(9)/l on day 15, the reticulocyte count rose above 1% on day 23, and the platelet count was over 50 x 10(9)/l on day 27, respectively. Cytogenetic studies of blood and marrow showed donor/recipient mixed chimerism. Rapid autologous hematopoietic recovery was recognized after withdrawal of CYA and mPSL. Repeated pathological examinations of the skin revealed no evidence of acute GVHD. Eighty-two days after the irradiation, skin transplantation was performed to treat radiation burns. Almost 90% of the transplanted skin engrafted. Immunological examination after autologous hematopoietic recovery revealed an almost normal T cell count. However, immune functions were severely impaired. The patient died from infectious complication 210 days after the accident.

Adult↗
PubMed2002

Chromosomal instability and radiosensitivity in myelodysplastic syndrome cells.

Myelodysplastic syndrome (MDS) is a clonal disorder of hematopoietic stem cells. To investigate whether chromosomal instability and/or DNA repair defects are involved in the development of MDS, we measured the micronucleus (MN) frequency in peripheral blood lymphocytes exposed to various doses of X-rays, using a cytokinesis-block micronucleus assay. The spontaneous MN frequencies in RAEB and RAEB-T patients were significantly higher than those in normal individuals (P = 0.0224, P = 0.008, respectively). Also, the X-ray-induced MN frequencies in RA/RARS, RAEB, and RAEB-T patients were significantly higher than those in normal individuals (P = 0.007, P = 0.003, P = 0.003, respectively, at 2 Gy). In order to elucidate the cause of unusual radiosensitivity, we measured the expression levels of nucleotide excision repair (NER) genes in peripheral blood mononuclear cells using a RT-PCR method. Reduction of NER gene expression was found in only one of 10 patients with low risk MDS, but in four of 11 patients with high risk MDS. Our data suggest that chromosomal instability and DNA repair defects may be involved in the pathophysiology of disease progression of MDS.

Adult↗
PubMed2002

Randomized clinical trial of long-term outcome after resection of hepatitis C virus-related hepatocellular carcinoma by postoperative interferon therapy.

BACKGROUND: Interferon therapy seems to decrease the incidence of recurrence after resection of hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC). Effects of postoperative interferon therapy on the survival rate after resection of such HCC are still unclear. METHODS: A prospective randomized clinical trial of postoperative interferon therapy was performed. Thirty men were allocated randomly after liver resection to an interferon-alpha group (15 patients) or a control group. Patients in the interferon group received interferon-alpha 6 MIU intramuscularly every day for 2 weeks, then three times a week for 14 weeks and finally twice a week for 88 weeks. RESULTS: The response to interferon was complete in two patients, there was a biochemical response in six patients and no response in seven patients. Interferon administration was not completed in three patients because of adverse events. Liver function did not change or worsened after operation in the control group, and did not change or improved in the interferon group. The cumulative survival rate was higher in the interferon group than in the control group (P = 0.041). CONCLUSION: Postoperative interferon therapy seems to improve the outcome after resection of HCV-related HCC.

Aged↗
PubMed2002

Evidence that action potential generation is not the exclusive determinant to trigger spontaneous myogenic contraction of guinea-pig urinary bladder smooth muscle.

Urinary bladder smooth muscle (UBSM) exhibits spontaneous contraction. This spontaneous mechanical activity is myogenic and can be closely related to the UBSM cell action potential to facilitate Ca2+ influx through voltage-gated Ca2+ channels. In the present study, to know whether this membrane electrical event is the exclusive mechanism to trigger spontaneous smooth muscle contraction, we compared the inhibitory effects of Ca2+ channel blockers on the spontaneous action potential and mechanical activity in the isolated guinea-pig UBSM. Both action potential and rhythmic contraction were generated spontaneously in the presence of atropine (1 microM), phentolamine (1 microM), propranolol (1 microM), suramin (10 microM) and tetrodotoxin (1 microM), which suggest that both phenomena were myogenic in origin. Nisoldipine (100 nM) and diltiazem (10 microM) completely eliminated the generation of action potential whereas its frequency was dramatically increased by a dihydropyridine Ca2+ agonist, BayK 8644 (1 microM). In contrast to disappearance of action potential in the presence of Ca2+ channel blockers, spontaneous contraction of UBSM was inhibited only partly by nisoldipine or diltiazem and most of the mechanical components persisted in these channel blockers. These results indicate that spontaneous action potential in UBSM cell is generated through the activation of L-type voltage-gated Ca2+ channels. The subsequent elevation of intracellular Ca2+ concentrations during a burst of action potentials can be partly responsible for the induction of UBSM mechanical activity. In addition, the present study provides evidence that UBSM spontaneous mechanical activity is also attributable to the mechanism(s) other than the generation of Ca2+ spike.

Action Potentials↗
PubMed2002

A case of febrile ulceronecrotic Mucha-Habermann disease requiring debridement of necrotic skin and epidermal autograft.

We report a case of febrile ulceronecrotic Mucha-Habermann disease (FUMHD) in a 21-year-old man. This disease is a severe form of pityriasis lichenoides et varioliformis acuta (PLEVA) and is characterized by the sudden onset of diffuse ulcerations associated with high fever and systemic symptoms. It is sometimes lethal especially in elderly patients. In the present case, intense generalized maculopapular erythematous plaques with central necrosis developed progressively in association with a high fever. Initial treatment with systemic betamethasone had been unsuccessful and the skin lesions, which covered about 50% of the body surface, became severely ulcerated. Although the development of new lesions had ceased spontaneously, widespread ulceration of the skin remained. Debridement of the necrotic skin and skin grafting using cultured epidermal autografts and meshed allografts of cadaver skin led to prompt reepithelization.

Adult↗
PubMed2002

Esophageal hernia in dementia: surgeon's role for mixed-type esophageal hernia in an elderly woman with dementia.

The mixed-type esophageal hernia is an indication for operation to prevent stomach volvulus and perforation. However, preventive operation is meaningful depending on the physical status. We encountered an 84-year-old, demented, bed-ridden woman of mixed-type esophageal hernia complicated with severe reflux esophagitis. First, the patient was conservatively treated by intravenous hyperalimentation and H2 blocker but, with onset of delirium, she removed the venous route twice. Subsequently, she was tightly restrained to the bed to avoid removing the line. Ethical deliberation for the patient tightly fixed to the bed and intravenous alimentation for her life prompted us to reconsider hernia operation after discussion with surrogate decision makers. The patient recovered uneventfully after operation, and movement without intravenous route or without any restraints was maintained by oral feeding assisted by gastrostomy feeding. In the coming decade, when senior patients are expected to increase, such operations can be forwarded to respect the patients' quality of life.

Aged↗
PubMed2002

Comparison of three-dimensional, two-dimensional and color Doppler ultrasound in predicting the presence of a nuchal cord at birth.

OBJECTIVES: To compare the use of two-dimensional, color Doppler and three-dimensional ultrasound for predicting the presence of a nuchal cord at birth. METHODS: Eighty-five singleton pregnancies without nuchal cord and 35 with nuchal cord (30 with a single coil of cord, four with a double coil, and one in which the cord was coiled around the neck three times) were studied within 1 week before delivery using transabdominal three-dimensional sonography. Two-dimensional and color Doppler ultrasound were also conducted for comparison. RESULTS: Two-dimensional, color Doppler and three-dimensional sonography identified in utero 24 (69%), 29 (83%) and 25 (71%), respectively, of the cases of nuchal cord found at birth. There were no significant differences in overall diagnostic indices of each diagnostic modality for detecting nuchal cord. However, the ability to view the nuchal cord (subjective assessment of the ease of visualization of nuchal cord) was better with three-dimensional sonography than with two-dimensional or color Doppler ultrasound. CONCLUSIONS: Three-dimensional surface imaging does not provide more useful diagnostic information compared with two-dimensional and color Doppler ultrasound for detecting nuchal cord in utero.

Female↗