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Articles by K Yoshida
Total Records ( 5 ) for K Yoshida
  K Yoshida , K Nakachi , K Imai , J. B Cologne , Y Niwa , Y Kusunoki and T. Hayashi
 

Lung cancer is a leading cause of cancer death worldwide. Prevention could be improved by identifying susceptible individuals as well as improving understanding of interactions between genes and etiological environmental agents, including radiation exposure. The epidermal growth factor receptor (EGFR)-signaling pathway, regulating cellular radiation sensitivity, is an oncogenic cascade involved in lung cancer, especially adenocarcinoma. The cytosine adenine (CA) repeat number polymorphism in the first intron of EGFR has been shown to be inversely correlated with EGFR production. It is hypothesized that CA repeat number may modulate individual susceptibility to lung cancer. Thus, we carried out a case–cohort study within the Japanese atomic bomb (A-bomb) survivor cohort to evaluate a possible association of CA repeat polymorphism with lung cancer risk in radiation-exposed or negligibly exposed (<5 mGy) A-bomb survivors. First, by dividing study subjects into Short and Long genotypes, defined as the summed CA repeat number of two alleles ≤37 and ≥38, respectively, we found that the Short genotype was significantly associated with an increased risk of lung cancer, specifically adenocarcinoma, among negligibly exposed subjects. Next, we found that prior radiation exposure significantly enhanced lung cancer risk of survivors with the Long genotype, whereas the risk for the Short genotype did not show any significant increase with radiation dose, resulting in indistinguishable risks between these genotypes at a high radiation dose. Our findings imply that the EGFR pathway plays a crucial role in assessing individual susceptibility to lung adenocarcinoma in relation to radiation exposure.

  M Kodama , K Tsukamoto , K Yoshida , K Aoki , S Kanegasaki and G. Quinn
 

Pancreatic β cell regeneration remains poorly understood, yet stimulation of adult β cell neogenesis could lead to therapies for type 1 and type 2 diabetes. We studied the effect of embryonic stem (ES) cell transplantation on pancreas regeneration following β cell injury. Female Balb/c nude mice were treated with streptozotocin to induce hyperglycemia and received an ES cell transplant 24 hr later beneath the renal capsule. Transplantation of ES cells prevented hyperglycemia in a subset of mice, maintaining euglycemia and mild glucose tolerance up to 5 weeks. Pancreata of euglycemic mice showed histological evidence of β cell regeneration and expression of pancreas and duodenum transcription factor-1 (PDX-1) and neurogenin 3 (Ngn3) in ductal epithelium. Cell tracing analysis indicated that significant β cell neogenesis from progenitor cells occurred between 2 to 3 weeks following injury in ES cell–transplanted mice but not in sham-transplanted animals. Significantly, whereas pancreas-localized ES cells or their derivatives were adjacent to sites of regeneration, neogenic pancreatic epithelia, including Ngn3+ cells, were endogenous. In conclusion, transplanted ES cells can migrate to the injured pancreas. Transplantation is associated with enhanced endogenous regeneration characterized by expression of Ngn3 and increased β cell differentiation from endogenous progenitor cells. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials. (J Histochem Cytochem 57:1149–1158, 2009)

  Y Iwamoto , H Kaneko , K Yoshida and H. Shimazu
 

The immediate premotor signals for saccades are created at the level of medium-lead burst neurons (MLBNs). During fixations, MLBNs receive tonic inhibition from omnipause neurons (OPNs), which use glycine as a neurotransmitter. To elucidate the role of this inhibition, we studied discharge patterns of horizontal MLBNs following iontophoretic application of strychnine, a glycine-receptor antagonist, in alert cats. Three-barrel micropipettes were used for extracellular recording and iontophoresis. After application of strychnine, MLBNs exhibited spontaneous discharge and visual responses during intersaccadic intervals. Spikes were evoked by single-pulse stimulation of the contralateral superior colliculus (SC). These results show that MLBNs receive substantial excitatory input during intersaccadic intervals and that inhibitory action of OPNs is indeed necessary to prevent MLBNs from firing. Strychnine also affected saccade-related activity of MLBNs. The burst of activity, as in normal conditions, declined rapidly before the end of saccades but was followed by low rate spike activity, which continued beyond the end of saccades. This suggests that in normal conditions, the termination of saccades is determined by resumed inhibitory action of OPNs and not by termination of excitatory input to MLBNs. In addition, the firing rate and the number of spikes during saccades increased after strychnine application, suggesting that MLBNs receive glycinergic inhibition of non-OPN origin as well. We conclude that glycinergic inhibition plays essential roles in the maintenance of stable fixation, the termination of saccades, and the regulation of saccade size and velocity.

  Y Horie , A Meguro , M Ota , N Kitaichi , Y Katsuyama , Y Takemoto , K Namba , K Yoshida , Y. W Song , K. S Park , E. B Lee , H Inoko , N Mizuki and S. Ohno
 

Objectives. HLA-B51 is strongly associated with Behçet's disease (BD) in any ethnic background. We recently reported that another gene, Toll-like receptor-4 (TLR4) is also implicated in BD in a Japanese population. To confirm these results, we investigated polymorphisms in the TLR4 gene in Korean patients with BD.

Methods. In this study, 119 patients with BD and 141 healthy controls were enrolled; every participant was a Korean. Nine single nucleotide polymorphisms previously detected in TLR4 by direct sequencing were analysed for an association with BD.

Results. The most frequent haplotype, TAGCGGTAA, was significantly increased in HLA-B*51-positive BD patients (49.5%), compared with healthy control participants [32.3%; P = 0.029; odds ratio (OR) = 2.01; 95% CI 1.25–3.23]. This haplotype was also significantly increased in BD patients with arthritis (48.2%; P = 0.003; OR = 1.96; 95% CI 1.26–3.26). There were no significant differences in the allele and genotype frequencies of patients and controls for each single nucleotide polymorphism.

Conclusions. The haplotype of TLR4 may increase the risk for developing BD and the complication of arthritis in the Korean population.

 
 
 
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