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Biomedical subjects

T Kodama

Publications and source records attributed to T Kodama.

At least 163 records · Page 9Linked to original sources
PubMed2000

Purification and characterization of membrane-bound hydrogenase from Hydrogenobacter thermophilus strain TK-6, an obligately autotrophic, thermophilic, hydrogen-oxidizing bacterium.

A membrane-bound hydrogenase was purified to electrophoretic homogeneity from the cells of Hydrogenobacter thermophilus strain TK-6, an obligately autotrophic, thermophilic, hydrogen-oxidizing bacterium. Solubilization and purification were done aerobically in the presence of Triton X-100. Three chromatography steps were done for purification; Butyl-Sepharose, Mono-Q, and Superose 6, in this order. Purification was completed with 6.73% yield of total activity and with 21.4-fold increase of specific activity when compared with the values for the membrane fraction. The purified hydrogenase was shown to be a tetramer with alpha2beta2 structure, with a molecular mass of 60,000 Da for the large subunit and 38,000 Da for the small subunit. The purified hydrogenase directly reduced methionaquinone with an apparent Km of around 300 microM and with a turnover number around 2900 (min(-1)). Metal analysis and EPR properties of the hydrogenase have shown that the enzyme is one of the [NiFe]-hydrogenases. Also, optimum pH and temperature for reaction, thermal stability, and electron acceptor specificity were reported. Finally, a model is presented for energy and central metabolism of H. thermophilus strain TK-6.

Amino Acid Sequence↗
PubMed2000

Structure of ribulose 1,5-bisphosphate carboxylase/oxygenase gene cluster from a thermophilic hydrogen-oxidizing bacterium, Hydrogenophilus thermoluteolus, and phylogeny of the fructose 1,6-bisphosphate aldolase encoded by cbbA in the cluster.

Four genes, cbbO, cbbY, cbbA, and the pyruvate kinase gene (pyk), were found downstream of ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) genes, cbbLS, from a thermophilic hydrogen-oxidizing bacterium, Hydrogenophilus thermoluteolus (formerly Pseudomonas hydrogenothermophila). cbbO was similar to norD in the denitrification gene cluster, and cbbY was similar to cbbY from other autotrophic bacteria. cbbA encoded fructose 1,6-bisphosphate aldolase (FBP aldolase); however, CbbA was little similar to other CbbA proteins. When CbbA was overexpressed in Escherichia coli, overproduction of CbbA was detected by SDS-PAGE. However, the cell extract had slightly higher activity than a cell extract of E. coli without cbbA. Phylogenetic analysis showed class II FBP aldolase divided into classes IIA and IIB, and that CbbA from H. thermoluteolus was in class IIA. Activities of RubisCO and FBP aldolase were examined under autotrophic, mixotrophic, and heterotrophic conditions. The activities of the two enzymes were regulated independently.

Amino Acid Sequence↗
PubMed2000

Video-assisted contralateral treatment for bronchial stump diastasis after left pneumonectomy.

Postoperative bronchial stump failure is a life-threatening complication, and several surgical approaches and procedures have been developed to close the stump. In this report, we describe a case of left mainstem bronchial stump diastasis after pneumonectomy for lung cancer, in which the bronchial stump was re-closed using a contralateral approach with video-assisted thoracic surgery, with good success. The left main bronchus was closed with an automatic stapler device, but the stump reopened and left pyothorax developed postoperatively. Emergent intratracheal intubation and ventilation was required due to rapid progression of right pyothorax. Under strict nutritional management by IV hyperalimentation, administration of antibiotics to which the organisms were sensitive, and drainage, the patient recovered from pneumonia. However, thoracic air leak increased daily, and reoperation for bronchial diastasis was performed. Using this approach, the left main bronchus near the carina was easily exposed extrapleurally, with only the azygos vein being incised. Video-assisted contralateral treatment was effective in avoiding sternal osteomyelitis due to a transpericardial approach via median sternotomy in the case of mainstem bronchial stump failure, only after left pneumonectomy.

Bronchi↗
PubMed2000

In vitro model of atherosclerosis using coculture of arterial wall cells and macrophage.

In order to determine the precise mechanism of the interactions between different types of cells, which are common phenomena in tissues and organs, the importance of coculture techniques are becoming increasingly important. In the area of cardiology, artificial arteries have been developed, based on the understanding of physiological communication of the arterial smooth muscle cells (SMC), endothelial cells (EC), and the extracellular matrix (ECM). In the study of atherosclerosis, the modification of low-density lipoprotein (LDL), which result in the recruitment and accumulation of white blood cells, especially, monocytes/macrophages, and foam cell formation, are hypothesized. Although there are well known animal models, an in vitro model of atherogenesis with a precisely known atherogenesis mechanism has not yet been developed. In this paper, an arterial wall reconstruction model using rabbit primary cultivated aortic SMCs and ECs, was shown. In addition, human peripheral monocytes were used and the transmigration of monocytes was observed by scanning electron and laser confocal microscopy. Monocyte differentiation into macrophages was shown by immunohistochemistry and comprehensive gene expression analysis. With the modified form of LDL, the macrophages were observed to accumulate lipids with a foamy appearance and differentiate into the foam cells in the ECM between the ECs and SMCs in the area of our coculture model.

Animals↗
PubMed2000

The inhibitory effect of cisplatin in combination with irradiation on lung tumor cell growth is due to induction of tumor cell apoptosis.

Chemoradiation is becoming an important method of treatment of advanced lung cancer. Although many studies have demonstrated the efficacy of chemoradiation against lung tumors, the mechanism of its effect is still poorly understood. In this study, we analyzed the combined effect of cisplatin (CDDP) and irradiation on human lung cancer cell lines (PC-9 and Lu 134A) in vitro using MTT assay and isobologram analysis. To study whether the combined effect is due to induction of tumor cell apoptosis, we further quantified the nuclear fragmentation of tumor cells by flow cytometric analysis. Our study revealed that a combination of cisplatin and irradiation had an additive inhibitory effect on both PC-9 (adenocarcinoma) and Lu 134A (small cell carcinoma) tumor cell growth. Cisplatin improved the sensitivity of tumor cells to irradiation. The use of both cisplatin and irradiation doses could be reduced without decreasing the inhibitory effect. The additive inhibitory effect was correlated positively with the levels of tumor cell nuclear fragmentation. We concluded that combination treatment with cisplatin and irradiation is effective against lung tumors, not only small cell carcinoma but also non-small cell carcinoma, and the inhibitory effect was due to induction of tumor cell apoptosis.

Adenocarcinoma↗
PubMed2000

Relative induction of mRNA for HMG CoA reductase and LDL receptor by five different HMG-CoA reductase inhibitors in cultured human cells.

The effect of various 3-hydroxy-3 methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors on the induction of HMG-CoA reductase and low density lipoprotein (LDL) receptor mRNA were quantitatively determined in the cultured human hepatoma cell line Hep G2 by means of a ribonuclease protection assay. Lipophilic inhibitors including mevastatin, simvastatin, atorvastatin and NK-104 were able to increase the levels of mRNAs for HMG-CoA reductase and the LDL receptor, but the hydrophilic inhibitor pravastatin was not effective in Hep G2 cells as had previously been reported. The LDL receptor mRNA was induced by NK-104 most effectively between 0.1 to 10 microM among the lipophilic inhibitors, whereas the degrees of induction of HMG-CoA reductase mRNA by these inhibitors did not differ significantly from each other. When cells were treated with a 200-fold excess of the IC50 concentration of each inhibitor, NK-104 was able to induce LDL receptor mRNA most effectively. These results indicate that the effect of HMG-CoA reductase inhibitors on the upregulation of mRNA for reductase and LDL receptor are different from each other and among these lipophilic inhibitors. NK-104 is most effective in inducing LDL receptor mRNA in Hep G2 cells.

Atorvastatin↗
PubMed2000

Genomic structure and mapping of human orphan receptor LXR alpha: upregulation of LXRa mRNA during monocyte to macrophage differentiation.

In order to identify changes in the gene expression profile during human monocyte/macrophage differentiation in the presence of GM-CSF, the expression level of various mRNA was studied using DNA microarray technology. We found LXR alpha (LXRa) to be the most highly induced transcriptional regulator during macrophage differentiation. The LXRa mRNA level was induced 40 fold which ranked it as the 10th highest among the approximately 5,600 genes studied. Although only restricted hepatic expression of LXRa mRNA had been reported, the macrophage expressed the highest level of LXRa among the nine human tissues and cultured cells studied. To further investigate transcriptional control, we have characterized the genomic structure of the human LXRa gene and determined the structure of its promoter region. The human LXRa gene consists of eleven exons, and analysis of the promoter region indicated the presence of conserved binding sites for myeloid zinc finger protein 1, which may be related to the extrahepatic expression of LXRa. LXRa is known to be activated by oxysterols, and the induced expression of the gene may be related to the foam cell formation in atherosclerotic lesions.

Base Sequence↗
PubMed2000

Gene expression induced by BO-653, probucol and BHQ in human endothelial cells.

2, 3-Dihydro-5-hydroxy-2, 2-dipentyl-4, 6-di-tert-butylbenzofuran (BO-653) and probucol, which act as radical scavenging antioxidants, were developed as anti-atherosclerotic medicines. In order to investigate the effect of these antioxidants on cell functions, we analyzed their ability to regulate gene expression in cultured human umbilical vein endothelial cells (HUVECs) using an oligonucleotide chip. Among 6,416 genes, 17 genes including those encoding mitochondrial proteins and proteins related to oxidative stress response were induced more than 3 fold by BO-653, probucol and tert-butylated hydroquinone (BHO). On the other hand, genes of three subunits of proteasome (PSMA2, PSMA3, PSMA4) were down-regulated by these antioxidants. A gene of cytochrome P-450 1A1 isozyme, a drug-metabolizing phase I enzyme, was expressed only by BHQ treatment. These results suggested that anti-atherogenic antioxidants affected gene expression in HUVECs by which they might regulate cell functions against oxidative stress.

Antioxidants↗
PubMed2000

The gene expression profile of human umbilical vein endothelial cells stimulated by tumor necrosis factor alpha using DNA microarray analysis.

Stimulation of vascular endothelial cells by tumor necrosis factor alpha (TNFalpha) plays a critical role in the pathogenesis of inflammation and vascular diseases. Changes in the gene expression profile in cultured human umbilical vein endothelial cells (HUVEC) treated with TNFalpha was analyzed with high-density oligonucleotide arrays comprised of 35,000 genes. TNFalpha stimulation profoundly induced genes involved in signal transduction, leukocyte adhesion and chemoattraction. ICAM-1 mRNA (fold change 111.9) was most profoundly induced followed by TNFalpha receptor-associated factor 1 (TRAF1) (95.5), Bcl3 (71.8), IL8 (65.4), fractalkaine (62.4), E-selectin (48.0), lymphotoxin beta (41.3) and VCAM-1 (31.7). In addition to these previously known genes, 18 poorly characterized or novel genes known as ESTs profoundly induced by TNFalpha. Initial sequencing analysis identified three of these the genes for squalene epoxydase, chromodomain helicase DNA binding protein 4, and CLP respectively. Further analysis of these genes will provide important information about TNFalpha signaling and function in vascular endothelial cells.

Cell Line↗
PubMed2000

A novel zinc finger protein mRNA in human umbilical vein endothelial cells is profoundly induced by tumor necrosis factor alpha.

Zinc finger proteins are known to mediate various transcriptional control mechanisms and other cellular functions in human cells. Tumor necrosis factor alpha (TNFalpha) induces a variety of genes in human endothelial cells including A20, an antiapoptotic zinc finger protein. In order to identify other zinc finger protein genes induced by TNFalpha, we studied the gene expression profile of human umbilical vein endothelial cells (HUVECs) stimulated by TNFalpha by means of oligonucleotide microarrays. Among the 155 genes encoding zinc finger motif, the level of EST M88357 mRNA encoding a novel designated EZFIT (endothelial zinc finger protein induced by TNFalpha) was induced most profoundly (>19 fold). The EZFIT gene is located on the chromosome 19q13.4. Isolation of the full length cDNA coding sequence by PCR using primers architected from the genomic sequence revealed that EZFIT has 490 amino acids which contain 13 C2H2 zinc finger motifs. Among 24 human organs and cell types studied, EZFIT mRNA was found to be most highly expressed in the placenta followed by the brain, testis, pancreas, heart, small intestine, muscle, uterus, prostate and peripheral blood leukocytes. EZFIT mRNA was not detected in the liver, lung, colon, stomach, the salivary gland or the thyroid gland.

Amino Acid Sequence↗
PubMed2000

[Genetic counseling and clinical genetics services for cancer prone kindreds].

Gene testing elucidates the identification of heterozygous carrier for hereditary cancer and the needs for genetics services are increasing in cancer hospitals. Genetic services include educational explanation for the disease and Mendelian inheritance, risk assessment, orientation for gene testing, post-test counseling for cancer prevention and psychosocial issues, and support services. This review outlines how they are performed in the clinic of cancer hospital.

Female↗
PubMed2000

[Temporal bone imaging].

With the advent of high-resolution computed tomography (HRCT), diagnostic imaging has played important roles in the evaluation and management of diseases in the temporal bone. Recent advanced technology such as, multi detector-raw, sub-millimeter slice thickness (0.5 mm), high-speed rotation (0.5 sec/rot), can make more accurate and rapid examination possible. Magnetic resonance imaging (MRI) can provide additional information because of its high contrast of soft tissues. In this article, characteristic findings of several diseases in the temporal bone, such as, anomaly, cholesteatoma, cholesterol granuloma, glomus tumor and other tumors, are presented.

Cholesteatoma, Middle Ear↗
PubMed2000

Intrapulmonary lymph nodes detected by exploratory video-assisted thoracoscopic surgery: appearance of helical computed tomography.

The objective of this study was to analyze helical computed tomography (CT) findings of intrapulmonary lymph nodes (IPLNs), and to evaluate the diagnostic procedures to prevent unnecessary exploratory surgery. Between April 1997 and March 2000, we performed exploratory video-assisted thoracoscopic surgery (E-VATS) in 42 patients and in 8 patients (4 men, 4 women; 48 to 75 years of age, mean 57 years) IPLN was pathologically proven. Retrospectively, the appearances of IPLN in helical CT images were studied in detail. The diameter of the IPLNs varied from 4 to 10mm. Six nodules were located in the lower lobes and 2 nodule was in the lingula. Chest CT showed several malignancy-suggesting associated findings with pleural indentation (2/8), spicular radiation (2/8), fuzzy margins (4/8), and vascular involvement (2/8). Black colored anthracoses in 5 subpleural IPLNs were confirmed by thoracoscopy. One patient with two coin lesions was suggestive of lung metastasis of adenoidcystic carcinoma of the tongue, but one lesion was proven as IPLN, and the other as metastatic carcinoma. In conclusion, it is not possible to distinguish an intrapulmonary lymph node from a malignant lesion using the CT findings preoperatively. Therefore, a pathological study with E-VATS is necessary and sure procedure to exclude malignant disease under the present conditions.

Aged↗
PubMed2000

State-dependency of neuronal slow dynamics during sleep observed in cat lateral geniculate nucleus.

From the accumulated results, we hypothesize that neurons in the central processor systems of the brain generally exhibit a common state-dependency in slow dynamics of their spontaneous activities during sleep. In this paper, activities of relay cells in the cat's lateral geniculate nucleus (LGN) were studied to see if our hypothesis can be applied in this thalamic region. Data segments in polygraphically steady states were strictly extracted in order to sample the activities whose stationarity was guaranteed in a statistical sense. During slow wave sleep (SWS), the discharge pattern was characterized by short bursts. In contrast, the rather tonic discharge pattern was observed to prevail during rapid eye movement (REM) sleep. Spectral analyses showed white noise-like spectra in the low frequency range of 0.04-1.0 Hz during SWS, and 1/f noise-like spectra in the same frequency range during REM sleep. This state-dependency of the slow dynamics was consistently characterized by the other statistical parameters concerning the second-order moment as well. In contrast, the fast dynamics over 1.0 Hz tended to exhibit neuron-specific changes associated with the sleep state in terms of the Markovian dependency analysis. Consequently, our working hypothesis was not rejected for the LGN relay cells. The result here extends the possibility that the state-dependency of the slow dynamics we found is a general rule concerning single neuronal dynamics in widespread areas of the brain during sleep. The state-dependency of the slow dynamics of the LGN relay cells could be understood according to the proposed mechanism that a state-associated alteration in the global biasing input to a neural network during sleep induces the phenomenon with which we are concerned. The slow dynamics of neuronal activities might provide a novel framework defining SWS and REM sleep states instead of the polygraphic characteristics.

Animals↗