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Articles by H Kobayashi
Total Records ( 8 ) for H Kobayashi
  H Kobayashi , M Matsuda , A Fukuhara , R Komuro and I. Shimomura
 

Oxidative stress plays an important role in obesity-related metabolic diseases. Glutathione peroxidase (GPX) is an antioxidant enzyme downregulated in adipose tissue of obese mice. However, the role of GPX in adipocytes remains elusive. The objective of this study was to clarify the pathophysiological changes in GPX activity and glutathione metabolism and their roles in the pathogenesis of insulin resistance in adipocytes. To achieve this goal, we measured cellular GPX activity, glutathione (GSH) contents, GSH/GSSG ratio, and mRNA expression of -glutamylcysteine synthetase (-GCS), a rate-limiting enzyme for de novo GSH synthesis, in adipose tissue of control and ob/ob mice and in 3T3-L1 adipocytes treated with insulin, H2O2, free fatty acid (FFA), or TNF. Furthermore, we investigated the effects of GPX inhibition with a specific GPX inhibitor or RNA interference against GPX, H2O2, and reduced GSH on insulin signaling in 3T3-L1 adipocytes. ob/ob Mice showed not only a decrease in cellular activity of GPXs (GPX1, -4, and -7) but also an increase in -GCS expression, resulting in increased GSH contents in adipose tissue. These alterations in glutathione metabolism were also observed during differentiation of 3T3-L1 cells and their exposure to insulin, FFA, or H2O2. Inhibition of GPX activity, addition of GSH, and H2O2 resulted in impaired insulin signaling in 3T3-L1 adipocytes. These results suggest that decreased GPX activity and increased -GCS expression lead to overaccumulation of GSH, which might be involved in the pathogenesis of insulin resistance in obesity.

  T Uno , K Isobe , N Ueno , H Kobayashi , Y Sanayama , A Mitsuhashi , M Shozu and H. Ito
  Objective

The aim of this study was to assess clinically the adequacy of vessel-contouring-based pelvic radiotherapy with regard to nodal coverage for uterine cervical cancer.

Methods

Fifty patients with Stages I–III cervical cancer, treated with vessel-contouring-based three-dimensional radiotherapy since August 2002, were entered into the study (median age: 54, 47 received concurrent daily cisplatin). All patients were treated with external beam radiotherapy using a four-field box technique with or without brachytherapy. Pelvic blood vessels were identified and contoured on computed tomography simulation images. A generous margin was set outside these vessels outlined on digitally reconstructed radiograph accounting for normal size lymph nodes, patient’s motion and set-up uncertainty. Multi-leaf collimator (MLC) was inserted and adjusted manually. Patterns of recurrence were clinically evaluated.

Results

Distance between major vessels and MLC edges varied inter- and intra-individually. Median distance in the mid-iliosacral joint level was 25 mm (left) and 24 mm (right). The maximum and the minimum distances ranged from 25 to 45 mm (median, 32) and 9 to 27 mm (median, 15) for left side and 24 to 41 mm (median, 30) and 7 to 28 mm (median, 15) for right side, respectively. With a median follow-up of 43 months, 10 patients developed recurrence. However, no marginal recurrence was occurred just lateral to the contoured vessels. All three patients who developed regional recurrence had recurred at the internal iliac node or the obturator node medial to contoured vessels.

Conclusions

Contoured vessels can be used as surrogate markers for location of the pelvic lymph nodes.

  H Kobayashi , T Uno , K Isobe , N Ueno , M Watanabe , R Harada , Y Takiguchi , K Tatsumi and H. Ito
  Objective

To examine the effects of dose–volume factors on the development of radiation pneumonitis in patients with non-small-cell lung cancer who received twice-daily radiotherapy concurrently with carboplatin and paclitaxel chemotherapy.

Methods

Radiotherapy consisted of twice-daily fractionation of 1.2 Gy, to a total dose of 60 Gy. Weekly carboplatin and paclitaxel were used as a concurrent chemotherapy. Effects of radiotherapy parameters on the development of radiation pneumonitis were retrospectively analyzed.

Results

Fourteen of 37 patients developed Grade 2 or worse (≥G2) radiation pneumonitis. Grade 2 or worse radiation pneumonitis occurred in all 5 patients with V5 >40%, all 4 patients with V10 >35%, all 4 patients with V13 >32%, 9 of 14 patients with V20 >24% and 8 of 11 patients with V30 >22%, whereas 9 of 32 patients with V5 <40%, 10 of 33 patients with V10 <35%, 10 of 33 patients with V13 <32%, 5 of 23 patients with V20 <24% and 6 of 26 patients with V30 <22%, with respective P values of 0.0045, 0.015, 0.015, 0.015 and 0.008. Eight of 11 patients with a mean lung dose of >14 Gy developed ≥G2 radiation pneumonitis in contrast to 6 of 26 patients with a mean lung dose of <14 Gy (P = 0.008).

Conclusions

Several cut-off values in the Vdose and the mean lung dose differentiating probabilities of developing ≥G2 radiation pneumonitis were identified in this combination therapy.

  T Kondo , Y Hashimoto , H Kobayashi , J Iizuka , T Nishikawa , M Nakano and K. Tanabe
  Objectives

We retrospectively analyzed our patients with advanced renal cell carcinoma who underwent presurgical targeted therapy with tyrosine kinase inhibitors to clarify the safety and clinical benefit. The histopathological effect of this treatment was also examined.

Methods

Between July 2005 and February 2010, nine patients with advanced renal cell carcinoma who were treated with tyrosine kinase inhibitors before surgery were the subjects of this study. Consolidative surgery was considered when these tumors showed clinical response or stable disease while on targeted therapy without evidence of disease progression at other sites.

Results

The agents used were sorafenib in seven patients and sunitinib in two. The median duration of presurgical therapy was 12.2 weeks, and seven patients had less than 4 months of treatment. Tumor reduction at 10–30% was obtained in all patients but one. Perioperative complications were observed in five of nine patients. Major complications occurred in two patients, including intraoperative excessive bleeding and delayed localized intraperitoneal abscess. Minor complications were found in three. The characteristics of the histopathological effect of tyrosine kinase inhibitors consisted of marked atrophy of the capillary sinus, confirming the pharmacological mechanisms of these agents. Other findings included nuclear pyknosis and degeneration of tumor cells.

Conclusions

Presurgical targeted therapy with tyrosine kinase inhibitors appears to be feasible in most patients with advanced renal cell carcinoma. However, the indications, the clinical benefit and the standard protocol still remain to be determined. Therapeutic effects in the histology were compatible to their pharmacological effects.

  K Tsunekawa , T Shijuku , M Hayashimoto , Y Kojima , K Onai , M Morishita , M Ishiura , T Kuroda , T Nakamura , H Kobayashi , M Sato , K Toyooka , K Matsuoka , T Omata and N. Uozumi
 

Na+/H+ antiporters influence proton or sodium motive force across the membrane. Synechocystis sp. PCC 6803 has six genes encoding Na+/H+ antiporters, nhaS1–5 and sll0556. In this study, the function of NhaS3 was examined. NhaS3 was essential for growth of Synechocystis, and loss of nhaS3 was not complemented by expression of the Escherichia coli Na+/H+ antiporter NhaA. Membrane fractionation followed by immunoblotting as well as immunogold labeling revealed that NhaS3 was localized in the thylakoid membrane of Synechocystis. NhaS3 was shown to be functional over a pH range from pH 6.5 to 9.0 when expressed in E. coli. A reduction in the copy number of nhaS3 in the Synechocystis genome rendered the cells more sensitive to high Na+ concentrations. NhaS3 had no K+/H+ exchange activity itself but enhanced K+ uptake from the medium when expressed in an E. coli potassium uptake mutant. Expression of nhaS3 increased after shifting from low CO2 to high CO2 conditions. Expression of nhaS3 was also found to be controlled by the circadian rhythm. Gene expression peaked at the beginning of subjective night. This coincided with the time of the lowest rate of CO2 consumption caused by the ceasing of O2-evolving photosynthesis. This is the first report of a Na+/H+ antiporter localized in thylakoid membrane. Our results suggested a role of NhaS3 in the maintenance of ion homeostasis of H+, Na+, and K+ in supporting the conversion of photosynthetic products and in the supply of energy in the dark.

 
 
 
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