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Articles by K Akita
Total Records ( 2 ) for K Akita
  K Hara , T Mochizuki , I Sekiya , K Yamaguchi , K Akita and T. Muneta
  Background

Double-bundle anterior cruciate ligament (ACL) reconstruction has several potential advantages over single-bundle reconstruction with hamstring tendons. However, there are still controversies regarding tunnel placement in tibial and femoral attachments.

Hypothesis

The macroscopically normal ACL consists of small bundles about 1 mm in diameter. Detailed observation of the divided smaller bundles will achieve better understanding of the tunnel placement in anatomic ACL reconstruction.

Study Design

Descriptive laboratory study.

Methods

This study used 20 cadaveric knees. The ACL was divided into anteromedial and posterolateral bundles, then separated into 10 small bundles of 2-mm diameters, with preservation of their attachment sites marked with color markers. The positional relationship between the femoral and tibial attachments of each small bundle was investigated.

Results

A layered positional correlation of small bundles was found between the tibial and femoral attachments. Small bundles aligned in the anterior-posterior direction in the tibia corresponded to the bundles aligned in a high-low direction in the femur in flexion. The femoral attachment pattern was relatively similar in each specimen; however, the tibial attachment showed 2 patterns: an oblique type (12 of 20) and a transverse type (8 of 20). The posterior portion of the posterolateral bundle was separately attached to the medial and lateral portions of the tibial attachment. There was no fibrous insertion in the center of the posterior portion of the ACL tibial attachment in any specimen. In this bare area, there was fat tissue and vascular bundles.

Conclusion

Small bundles constituting the ACL showed a relatively layered arrangement between 2 attachments. The tibial attachment showed 2 patterns of oblique and transverse types, and the vascular bundles were located in the center of the posterolateral bundle.

Clinical Relevance

The results of this study of the normal ACL will provide insights for surgeons when placing grafts during anatomic ACL reconstruction.

  K Akita , N Hieda , N Baba , S Kawaguchi , H Sakamoto , Y Nakanishi , M Yamanishi , K Mori and T. Toraya
 

The methods of homologous high-level expression and simple large-scale purification for coenzyme B12-dependent ethanolamine ammonia-lyase of Escherichia coli were developed. The eutB and eutC genes in the eut operon encoded the large and small subunits of the enzyme, respectively. The enzyme existed as the heterododecamer 6β6. Upon active-site titration with adeninylpentylcobalamin, a strong competitive inhibitor for coenzyme B12, the binding of 1 mol of the inhibitor per mol of the β unit caused complete inhibition of enzyme, in consistent with its subunit structure. EPR spectra indicated the formation of substrate-derived radicals during catalysis and the binding of cobalamin in the base-on mode, i.e. with 5,6-dimethylbenzimidazole coordinating to the cobalt atom. The purified wild-type enzyme underwent aggregation and inactivation at high concentrations. Limited proteolysis with trypsin indicated that the N-terminal region is not essential for catalysis. His-tagged truncated enzymes were similar to the wild-type enzyme in catalytic properties, but more resistant to p-chloromercuribenzoate than the wild-type enzyme. A truncated enzyme was highly soluble even in the absence of detergent and resistant to aggregation and oxidative inactivation at high concentrations, indicating that a short N-terminal sequence is sufficient to change the solubility and stability of the enzyme.

 
 
 
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