Biomedical subjects

Nobuhiro Hayashi

Publications and source records attributed to Nobuhiro Hayashi.

3 recordsLinked to original sources

PubMed2003

Regulation of endothelial nitric oxide synthase by protein kinase C.

Endothelial nitric oxide synthase (eNOS) is a key enzyme in nitric oxide-mediated signal transduction in mammalian cells. Its catalytic activity is regulated both by regulatory proteins, such as calmodulin and caveolin, and by a variety of post-translational modifications including phosphorylation and acylation. We have previously shown that the calmodulin-binding domain peptide is a good substrate for protein kinase C [Matsubara, M., Titani, K., and Taniguchi, H. (1996) Biochemistry 35, 14651-14658]. Here we report that bovine eNOS protein is phosphorylated at Thr497 in the calmodulin-binding domain by PKC both in vitro and in vivo, and that the phosphorylation negatively regulates eNOS activity. A specific antibody that recognizes only the phosphorylated form of the enzyme was raised against a synthetic phosphopeptide corresponding to the phosphorylated domain. The antibody recognized eNOS immunoprecipitated with anti-eNOS antibody from the soluble fraction of bovine aortic endothelial cells, and the immunoreactivity increased markedly when the cells were treated with phorbol 12-myristate 13-acetate. PKC phosphorylated eNOS specifically at Thr497 with a concomitant decrease in the NOS activity. Furthermore, the phosphorylated eNOS showed reduced affinity to calmodulin. Therefore, PKC regulates eNOS activity by changing the binding of calmodulin, an eNOS activator, to the enzyme.

Amino Acid Sequence↗

PubMed2002

Does reconstruction of posterior ligamentous complex with extensor musculature decrease axial symptoms after cervical laminoplasty?

STUDY DESIGN: The authors retrospectively determined the prevalence of neck and shoulder symptoms (axial symptoms) after expansive laminoplasty with reattachment of spinous process and extensor musculature in patients with cervical myelopathy. OBJECTIVES: To determine the prevalence of both preoperative and postoperative axial symptoms of expansive laminoplasty when they occur after expansive laminoplasty. SUMMARY OF BACKGROUND DATA: Several clinical reports have noted that laminoplasty for cervical myelopathy produces positive clinical outcomes. However, recent reports have pointed out that complications from laminoplasty, such as axial symptoms, may be severe enough to interfere with daily activities. METHODS: The authors used a modified spinous process-splitting laminoplasty, which involved reattaching the spinous process with extensor musculature after enlarging the spinal canal by use of the French window method. Postoperative axial symptoms were investigated in 173 of 214 patients (80.1%) who underwent expansive laminoplasty between January 1989 and December 1998. The patients included 121 men and 52 women, and their average age was 61.5 years. The presence or absence and grade of axial symptoms before and after laminoplasty were investigated. The severity and duration of complications were also recorded, along with differences between age, sex, spinal alignment, and cervical diseases. RESULTS: Neck and/or shoulder stiffness worsened in 15% of the patients and declined in 21%. Neck pain worsened in 10% of the patients and improved in 11%. Neck and/or shoulder stiffness worse than moderate was recognized in 14.4% of the patients. Neck pain worse than moderate was recognized in 5% of the patients. In the 137 patients who had no axial pain before surgery, only 13 patients experienced such symptoms after surgery, and in most cases these symptoms were minimal. In only 1 case, significant postoperative neck pain arose de novo as a result of this surgery. In 88 patients who had no neck and/or shoulder stiffness before surgery, only 16 patients experienced such symptoms after surgery, and in most cases these were minimal. A similar pattern held true for each of the other grades of preoperative axial symptoms. The recovery rate score (Japanese Orthopedic Association) was 47.5 +/- 32.3 in the patients whose axial symptoms were worse than moderate and 60 +/- 28.9 in patients whose axial symptoms were less than mild. This difference was significant (P < 0.05). CONCLUSION: Laminoplasty is an appropriate operation for cervical spondylotic myelopathy and did not, in this study, seem to have any significant influence on the development or resolution of axial symptoms.

Adult↗

PubMed2002

Nef of HIV-1 interacts directly with calcium-bound calmodulin.

It was recently found that the myristoyl group of CAP-23/NAP-22, a neuron-specific protein kinase C substrate, is essential for the interaction between the protein and Ca(2+)-bound calmodulin (Ca(2+)/CaM). Based on the N-terminal amino acid sequence alignment of CAP-23/NAP-22 and other myristoylated proteins, including the Nef protein from human immunodeficiency virus (HIV), we proposed a new hypothesis that the protein myristoylation plays important roles in protein-calmodulin interactions. To investigate the possibility of direct interaction between Nef and calmodulin, we performed structural studies of Ca(2+)/CaM in the presence of a myristoylated peptide corresponding to the N-terminal region of Nef. The dissociation constant between Ca(2+)/CaM and the myristoylated Nef peptide was determined to be 13.7 nM by fluorescence spectroscopy analyses. The NMR experiments indicated that the chemical shifts of some residues on and around the hydrophobic clefts of Ca(2+)/CaM changed markedly in the Ca(2+)/CaM-Nef peptide complex with the molar ratio of 1:2. Correspondingly, the radius of gyration determined by the small angle X-ray scattering measurements is 2-3 A smaller that of Ca(2+)/CaM alone. These results demonstrate clearly that Nef interacts directly with Ca(2+)/CaM.

Calcium↗