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Biomedical subjects

K Ota

Publications and source records attributed to K Ota.

At least 19 recordsLinked to original sources
PubMed2006

Oral health status of vulnerable groups in a village of the Central Highlands, southern Vietnam.

OBJECTIVES: Oral health status of vulnerable people in developing countries tends to be given lower priority than other health issues. Consequently, few studies have examined the oral health status of the poor and minorities in developing countries. We aim to examine the dental caries and periodontal status, and explore the risk indicators of dental caries between two ethnic groups in rural villages in southern Vietnam. METHODS: We examined the caries status and its risk indicators of 150 participants (Co-Ho minority and Kinh majority) living in a hamlet of Dangphuong village in Vietnam. We also assessed periodontal status of the participants aged 14 and over by Community Periodontal Index. RESULTS: We first found that dental caries were highly prevalent among both the Co-Ho minority and Kinh majority groups. Second, the higher numbers of dental caries among children with primary teeth were associated with a higher frequency of consuming sweets. Third, most people (87%) aged 14 and over had periodontal problems. Finally, the Kinh majority tended to have more dental caries than Co-Ho among people aged less than 30. CONCLUSION: Oral health promotion should be considered as a part of the development programmes for vulnerable groups in Vietnam and other developing countries.

Adolescent↗
PubMed2004

Current status of organ transplants in Asian countries.

The Asian Society of Transplantation, founded in 1989 includes Indonesia, Japan, Korea, Malaysia, Oman, Pakistan, Republic of China, Philippines, Saudi Arabia, Singapore, Taiwan, Thailand, and the United Arab Emirates (UAE). The registry was also started from the same year in cooperation with these 16 countries. A questionnaire was sent to the key person of each country every year. The questionnaire includes (a) number of centers that performed organ transplants, (b) varieties and numbers of organ transplants performed in 2000 and 2001, (c) present status of dialysis, number of dialysis patients, and number of the candidates on the list for transplantation, (d) number of patients going abroad for transplantation, and (e) recent transplant highlights, news and issues affecting each country during 2000 and 2001. We previously gathered data for 2000, except for Indonesia, Singapore, and the UAE. Regarding 2001 data, we will send the questionnaires to the countries involved.

Asia↗
PubMed2004

Review of combination of peritoneal dialysis and hemodialysis as a modality of treatment for end-stage renal disease.

Because the contribution of residual renal function (RRF) to total solute clearance is often significant in continuous ambulatory peritoneal dialysis (CAPD), loss of RRF over time can lead to inadequate dialysis if appropriate prescription management strategies are not pursued. Additionally, declines in ultrafiltration caused by increases in peritoneal permeability may limit continuation of CAPD therapy. Peritoneal dialysis and hemodialysis (PD + HD) combination therapy (complementary dialysis therapy) is an alternative method. This therapy allows the patient to maintain daily activities, as with CAPD, while undergoing once-a-week HD supplements for the insufficient removal of solutes and water. This therapy allows for the continuation of PD without shifting to total HD in PD patients who continue to have uremic symptoms even after individualization of the PD prescription. This treatment option is psychologically more acceptable to patients and may be expected to provide such accompanying beneficial effects as peritoneal resting, improvement of QOL and reduction in medical cost.

Combined Modality Therapy↗
PubMed2003

Influence of the mode of matrix porosity determination on matrix diffusion calculations.

The theoretical basis for matrix diffusion in fractured rocks and the methodology for the determination of diffusion coefficients in the laboratory are well established. One significant problem, however, remains in that it is difficult to quantify the degree of sample disturbance affecting the geometrical, geophysical and hydraulic properties of the rock matrix. A new technique, with in situ rock impregnation with resin, for examining the diffusion-accessible rock matrix has been developed and successfully adopted to the rock matrix behind a water-conducting fracture in host crystalline rocks at Nagra's Grimsel Test Site in Switzerland and JNC's Kamaishi In Situ Test Site in Japan. In line with the results of a large number of natural analogue and laboratory studies, the existence of an in situ interconnected pore network was substantiated. Matrix porosities determined on the laboratory samples from both the sites are 1.5-3 times higher than in situ values, irrespective of the technique applied. On the Grimsel granodiorite matrix, matrix porosity existing in situ and artefacts of stress release and physical disturbance, induced by sampling and sample preparation, were clearly distinguished, allowing in situ porosity to be quantified. Laboratory work with conventional techniques tends to overestimate the porosity of the rock matrix, hence leading to an overestimation of in situ matrix diffusion. The implications of these differences to a repository performance assessment are assessed with a couple of examples from existing assessments, and recommendations for future approaches to the examination of in situ matrix porosity are made.

Diffusion↗
PubMed2003

Functional interference between estrogen-related receptor alpha and peroxisome proliferator-activated receptor alpha/9-cis-retinoic acid receptor alpha heterodimer complex in the nuclear receptor response element-1 of the medium chain acyl-coenzyme A dehydrogenase gene.

We undertook a study of molecular interference of nuclear orphan receptors. Nuclear receptor response element-1 (NRRE-1) from the human medium-chain acyl coenzyme A dehydrogenase (MCAD) gene promoter was shown to contain three hexamer elements (site 1 through 3) that are known to interact with a number of nuclear receptors including chicken ovalbumin upstream promoter transcription factor (COUP-TF) and estrogen-related receptor alpha (ERRalpha). We demonstrated that the peroxisome proliferator-activated receptor alpha/9-cis-retinoic acid receptor alpha (PPARalpha/RXRalpha) heterodimer complex can also bind to the two hexamer repeat sequences (between site 1 and site 3) arranged as an everted imperfect repeat separated by 14 bp (ER14). Mutations of the putative core elements have shown that these three sites are differentially involved in ERRalpha and PPARalpha/RXRalpha binding. Homodimer of ERRalpha was shown to interact between site 1 and site 3 (ER14). To date, no nuclear receptor is known to bind to response elements over such long intervals. Interestingly, site 1 was shown to be essential for ERRalpha binding while site 3 supports its binding only in the presence of site 1. Furthermore, it was shown that the binding profile of ERRalpha and PPARalpha/RXRalpha are competitive rather than making a high order complex within NRRE-1. At the cellular level, transcriptional activation driven by the PPARalpha/RXRalpha complex was counteracted by the expression of ERRalpha in HeLa cells. These results suggest that ERRalpha and PPARalpha/RXRalpha could interfere with each other's function through binding to similar DNA elements, thereby finetuning the transcriptional outcome of the target gene. Our findings suggest a mechanism whereby multiple nuclear receptors can activate or repress DNA binding or transcription via a single pleiotropic regulatory element.

Acyl-CoA Dehydrogenase↗
PubMed2001

Differential expression of apoptotic protease-activating factor-1 and caspase-3 genes and susceptibility to apoptosis during brain development and after traumatic brain injury.

Neuronal apoptosis plays an essential role in early brain development and contributes to secondary neuronal loss after acute brain injury. Recent studies have provided evidence that neuronal susceptibility to apoptosis induced by traumatic or ischemic injury decreases during brain development. However, the molecular mechanisms responsible for this age-dependent phenomenon remain unclear. Here we demonstrate that, during brain maturation, the potential of the intrinsic apoptotic pathway is progressively reduced and that such repression is associated with downregulation of apoptotic protease-activating factor-1 (Apaf-1) and caspase-3 gene expression. A similar decline in apoptotic susceptibility associated with downregulation of Apaf-1 expression as a function of developmental age was also found in cultured primary rat cortical neurons. Injury-induced cytochrome c-specific cleavage of caspase-9 followed by activation of caspase-3 in mature brain correlated with marked increases in Apaf-1 and caspase-3 mRNA and protein expression. These results suggest that differential expression of Apaf-1 and caspase-3 genes may underlie regulation of apoptotic susceptibility during brain development, as well as after acute injury to mature brain, through the intrinsic pathway of caspase activation.

Aging↗
PubMed2001

Novel modular domain PB1 recognizes PC motif to mediate functional protein-protein interactions.

Modular domains mediating specific protein-protein interactions play central roles in the formation of complex regulatory networks to execute various cellular activities. Here we identify a novel domain PB1 in the budding yeast protein Bem1p, which functions in polarity establishment, and mammalian p67(phox), which activates the microbicidal phagocyte NADPH oxidase. Each of these specifically recognizes an evolutionarily conserved PC motif to interact directly with Cdc24p (an essential protein for cell polarization) and p40(phox) (a component of the signaling complex for the oxidase), respectively. Swapping the PB1 domain of Bem1p with that of p67(phox), which abolishes its interaction with Cdc24p, confers on cells temperature- sensitive growth and a bilateral mating defect. These phenotypes are suppressed by a mutant Cdc24p harboring the PC motif-containing region of p40(phox), which restores the interaction with the altered Bem1p. This domain-swapping experiment demonstrates that Bem1p function requires interaction with Cdc24p, in which the PB1 domain and the PC motif participate as responsible modules.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Effect of pre-and postoperative plasmapheresis on posttransplant recurrence of focal segmental glomerulosclerosis in children.

BACKGROUND: Posttransplant recurrence is frequent in patients who received renal transplantation for focal segmental glomerulosclerosis (FSGS). The recurrence has been ascribed to a circulating permeability factor or factors. We have used plasmapheresis (PP) to treat recurrent FSGS and also studied whether preoperative PP is effective in preventing recurrence of FSGS. METHODS: We retrospectively analyzed 21 allografts of 20 patients with nephrotic syndrome and biopsyproven FSGS. They were divided into two groups depending on whether they had prophylactic PP; a prophylactic (n=15) and a nonprophylactic group (n=6). PP was performed two to three times prophylactically and therapeutically until proteinuria was markedly reduced. In each session, 50-75 ml/kg of the patient's plasma was exchanged with 5-8% albumin. RESULTS: FSGS recurred in 9 of 21 allografts, 4 of 6 in the nonprophylactic group, and 5 of 15 in the prophylactic group. Therapeutic PP was performed in seven of nine recurrent patients without definite adverse effect, with satisfactory results except in one patient. Children lost proteinuria after 6 to > 100 sessions of PP and the number correlated with the pretreatment level of proteinuria. The mean follow-up periods were 62.7 and 41.6 months for the prophylactic and nonprophylactic groups, respectively. At the last follow-up, 66.7% of relapsing and 81.8% of nonrelapsing patients had a functioning graft. CONCLUSION: PP appears to be effective for the prevention and treatment of posttransplant recurrence of FSGS, although further consideration of cost/benefit and risks is required before a conclusive judgement can be made.

Child↗
PubMed2001

Budding yeast GCN1 binds the GI domain to activate the eIF2alpha kinase GCN2.

When starved for a single amino acid, the budding yeast Saccharomyces cerevisiae activates the eukaryotic initiation factor 2alpha (eIF2alpha) kinase GCN2 in a GCN1-dependent manner. Phosphorylated eIF2alpha inhibits general translation but selectively derepresses the synthesis of the transcription factor GCN4, which leads to coordinated induction of genes involved in biosynthesis of various amino acids, a phenomenon called general control response. We recently demonstrated that this response requires binding of GCN1 to the GI domain occurring at the N terminus of GCN2 (Kubota, H., Sakaki, Y., and Ito, T. (2000) J. Biol. Chem. 275, 20243-20246). Here we provide the first evidence for the involvement of GCN1-GCN2 interaction in activation of GCN2 per se. We identified a C-terminal segment of GCN1 sufficient to bind the GI domain and used a novel dual bait two-hybrid method to identify mutations rendering GCN1 incapable of interacting with GCN2. The yeast bearing such an allele, gcn1-F2291L, fails to display derepression of GCN4 translation and hence general control response, as does a GI domain mutant, gcn2-Y74A, defective in association with GCN1. Furthermore, we demonstrated that phosphorylation of eIF2alpha is impaired in both mutants. Since GCN2 is the sole eIF2alpha kinase in yeast, these findings indicate a critical role of GCN1-GCN2 interaction in activation of the kinase in vivo.

Amino Acid Sequence↗
PubMed2001

Thoracodorsal artery as a free arterial graft for myocardial revascularization.

When complete arterial revascularization of coronary circulation cannot be accomplished using the internal thoracic artery and other conventionally used arterial conduits, the thoracodorsal artery may be an excellent alternative. We report the use of the thoracodorsal artery as a free arterial graft in 3 patients, describe the harvesting technique, and review the anatomy.

Aged↗
PubMed2001

Development and testing of radionuclide transport models for fractured rock: examples from the Nagra/JNC Radionuclide Migration Programme in the Grimsel Test Site, Switzerland.

The joint Swiss National Co-operative for the Disposal of Radioactive Waste (Nagra)/Japan Nuclear Cycle Development Institute (JNC) Radionuclide Migration Programme has now been on-going for over a decade in Nagra's Grimsel Test Site (GTS). The main aim of the programme has been the direct testing of radionuclide transport models in as realistic manner as possible. Although it will never be possible to fully test these models due to the large time and distance scales involved, tests of the model assumptions in scaled down but otherwise realistic conditions will contribute to developing confidence in the predictive power of the models. In this paper, the Nagra/JNC approach is highlighted with examples from a large programme of field, laboratory and natural analogue studies based around the GTS. The successes and failures are discussed as in the general approach to the thorough testing of predictive transport codes which will be used in repository performance assessment (PA). Some of the work is still on-going and this represents the first presentation of a unique set of results and conclusions.

Geological Phenomena↗
PubMed2001

Engineering neoglycoproteins with multiple O-glycans using repetitive pentapeptide glycosylation units.

Controlled protein remodeling with O-linked glycans has been limited by our incomplete understanding of the process of glycosylation. Here we describe a secretable fibroblast growth factor (FGF) with multiple mucin-type O-glycans produced by introducing a minimum pentapeptide glycosylation unit in a decarepeat format at its N- or C-terminus. Expressed in Chinese hamster ovary cells, chemical and biochemical analyses of the resultant proteins (Nm10-FGF and Cm10-FGF, respectively) demonstrated that all O-glycosylation units were glycosylated and the dominant structure was sialylated Gal[beta1-3]GalNAc. This indicates that minimum O-glycosylation unit in multirepeat format serves as a remarkably efficient acceptor in CHO cells. The Nm10-FGF and Cm10-FGF proteins maintained the mitogenic activity to vascular endothelial cells. In addition, intact Cm10-FGF and its desialylated form interacted with several lectins in the same way as mucin-type glycoproteins. The intact Cm10-FGF with multiple sialylated O-glycans exhibited a longer lifetime in circulating blood, whereas the Cm10-FGF with desialylated O-glycans exhibited a shorter lifetime than the deglycosylated form of Cm10-FGF. Our approach would thus appear to be highly effective for engineering neoglycoproteins, the characteristics of which are determined by their multiple mucin-type O-glycans.

Animals↗
PubMed2001

Heteromorphic sex chromosomes of lizardfish (Synodontidae): focus on the ZZ-ZW1W2 system in Trachinocephalus myops.

The karyotype and DNA content of four lizardfish species (family Synodontidae), that is, Saurida elongata, Synodus ulae, Synodus hoshinonis and Trachinocephalus myops, were analyzed. The karyotype of T. myops significantly differed from that of the other three species having diploid chromosome number of 48 with mainly acrocentric chromosomes and the ZZ-ZW sex chromosome system. The chromosome number of male T. myops was 2n = 26, while that of female T. myops was 2n = 27. The karyotype consisted of 11 pairs of metacentrics, one pair of acrocentrics and, in addition, two large metacentrics in the male and a single large metacentric, a distinctly small subtelocentric and a microchromosome in the female. C-banding demonstrated that in the female the subtelocentric chromosome and the microchromosome were heterochromatic. The karyotype of T. myops was thought to be derived from a 48 chromosome type synodontid fish through the involvement of Robertsonian rearrangement; the rearrangement of the sex chromosomes proceeded during karyotype evolution. Among the chromosomes, the large metacentrics were determined to be neo-Z (a fusion of the original Z and an autosome), the microchromosomes the W1 (originally W), and the subtelocentric chromosomes the W2 (derived from an autosome pair). The miniaturization of W1 and W2 chromosomes and their heterochromatinization suggested that sex chromosomes in this species have been already highly differentiated. The findings on DNA content implied that the karyotype of T. myops evolved by centric fusion events without loss in DNA amount.

Animals↗
PubMed2001

Nodal gamma/delta T cell lymphoma in complete remission following allogeneic bone marrow transplantation from an HLA-matched unrelated donor.

Gamma/delta T cell lymphoma is very rare, and usually occurs as an extranodal tumor. We describe the case of a 16-year-old Japanese man with an unusual nodal gamma/delta T cell lymphoma with generalized lymphadenopathy and bone marrow involvement. No tumor involvement was observed in the liver, spleen, or nasal cavity. Examination for surface antigens on lymphoma cells revealed a unique phenotype, positive for CD3 and T cell receptor (TCR) gamma/delta, but negative for CD2. Genotypic analysis revealed the tumor to be of monoclonal origin and characterized by TCR gamma-chain gene rearrangement, but there was no rearrangement of the TCR beta-chain gene. Our patient's tumor responded to combination chemotherapy and subsequent allogeneic bone marrow transplantation from an HLA-matched unrelated donor. He has remained well and free of disease for 35 months.

Adolescent↗