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Articles by H Koga
Total Records ( 2 ) for H Koga
  H Takada , T Kawana , Y Ito , R. F Kikuno , H Mamada , T Araki , H Koga , M Asashima and M. Taira
  Hitomi Takada, Takahiro Kawana, Yuzuru Ito, Reiko F. Kikuno, Hiroshi Mamada, Toshiyuki Araki, Hisashi Koga, Makoto Asashima, and Masanori Taira

Post-transcriptional control by RNA-binding proteins is a precise way to assure appropriate levels of gene expression. Here, we identify a novel mRNA regulatory system involving Mex3b (RKHD3) and demonstrate its role in FGF signaling. mex3b mRNA has a 3' long conserved UTR, named 3'LCU, which contains multiple elements for both mRNA destabilization and translational enhancement. Notably, Mex3b promotes destabilization of its own mRNA by binding to the 3'LCU, thereby forming a negative autoregulatory loop. The combination of positive regulation and negative autoregulation constitutes a fine-tuning system for post-transcriptional control. In early embryogenesis, Mex3b is involved in anteroposterior patterning of the neural plate. Consistent with this, Mex3b can attenuate FGF signaling and destabilize mRNAs for the FGF signaling components Syndecan 2 and Ets1b through their 3' UTRs. These data suggest that the 3'LCU-mediated fine-tuning system determines the appropriate level of mex3b expression, which in turn contributes to neural patterning through regulating FGF signaling.

  H Koga , A Nakamae , Y Shima , J Iwasa , G Myklebust , L Engebretsen , R Bahr and T. Krosshaug
 

Background: The mechanism for noncontact anterior cruciate ligament injury is still a matter of controversy. Video analysis of injury tapes is the only method available to extract biomechanical information from actual anterior cruciate ligament injury cases.

Purpose: This article describes 3-dimensional knee joint kinematics in anterior cruciate ligament injury situations using a model-based image-matching technique.

Study Design: Case series; Level of evidence, 4.

Methods: Ten anterior cruciate ligament injury video sequences from women’s handball and basketball were analyzed using the model-based image-matching method.

Results: The mean knee flexion angle among the 10 cases was 23° (range, 11°-30°) at initial contact (IC) and had increased by 24° (95% confidence interval [CI], 19°-29°) within the following 40 milliseconds. The mean valgus angle was neutral (range, –2° to 3°) at IC, but had increased by 12° (95% CI, 10°-13°) 40 milliseconds later. The knee was externally rotated 5° (range, –5° to 12°) at IC, but rotated internally by 8° (95% CI, 2°-14°) during the first 40 milliseconds, followed by external rotation of 17° (95% CI, 13°-22°). The mean peak vertical ground-reaction force was 3.2 times body weight (95% CI, 2.7-3.7), and occurred at 40 milliseconds after IC (range, 0-83).

Conclusion: Based on when the sudden changes in joint angular motion and the peak vertical ground-reaction force occurred, it is likely that the anterior cruciate ligament injury occurred approximately 40 milliseconds after IC. The kinematic patterns were surprisingly consistent among the 10 cases. All players had immediate valgus motion within 40 milliseconds after IC. Moreover, the tibia rotated internally during the first 40 milliseconds and then external rotation was observed, possibly after the anterior cruciate ligament had torn. These results suggest that valgus loading is a contributing factor in the anterior cruciate ligament injury mechanism and that internal tibial rotation is coupled with valgus motion. Prevention programs should focus on acquiring a good cutting and landing technique with knee flexion and without valgus loading of the knee.

 
 
 
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