Biomedical subjects

Kazunao Kuramoto

Publications and source records attributed to Kazunao Kuramoto.

3 recordsLinked to original sources

PubMed2006

Calorie restriction initiated at middle age improved glucose tolerance without affecting age-related impairments of insulin signaling in rat skeletal muscle.

Calorie restriction (CR) may affect glucose tolerance via modulation of the insulin action in skeletal muscle. The present study investigated the effect of CR initiated at middle age in rats bearing glucose intolerance, in comparison with CR at a younger age. Male F344 rats at 2.5 and 18months (mo) of age were fed ad libitum (AL) or 30% CR diets for 4-4.5mo, subjected to glucose tolerance testing, and then sacrificed 15min after intraperitoneal glucose or saline injection to evaluate glucose-stimulated insulin response and subsequent activation of insulin signaling molecules. The protein abundance of phosphorylated (p) insulin receptors, p-Akt, and p-atypical PKC and the membrane fraction of glucose transporter 4 in quadriceps femoris muscle (QFM) were analyzed by EIA or immunoblotting. CR initiated either at young or middle age improved glucose tolerance with a lower serum insulin response to glucose. However, middle-aged CR did not improve aging-related impairments in insulin signaling in QFM. The present results emphasized the possibilities of CR activation of an insulin-independent mechanism in skeletal muscle and also of the involvement of non-muscle tissues in glucose uptake.

Adipose Tissue↗

PubMed2004

Mouse testis transcriptome revealed using serial analysis of gene expression.

We applied serial analysis of gene expression (SAGE) to the mouse testis to reveal the global gene expression profile and to identify senescence-dependent changes in that profile. A total of 61,929 SAGE tags, including 19,323 unique tags, were obtained from 3- and 29-month-old BDF1 mice and 14-month-old SAMP1 mice. Genes highly expressed in the testis included those associated with spermatogenesis, protein metabolism, energy metabolism, growth and differentiation, and signal transduction. Testes from old mice of both strains appeared atrophied. Morphological examination of aged testes revealed extremely thin seminiferous epithelia and significantly decreased numbers of spermatids and spermatocytes. Despite the physical deterioration, no gross changes in the gene expression profile were apparent in the testes of old BDF1 mice. However, in 14-month-old SAMP1 mice, protamine 2 gene transcription was approximately 50% lower than in BDF1 mice. This reduction may be associated with the oligozoospermia and early decline in reproductive performance of SAMP1 mice. Our SAGE results are the first quantitative gene expression profile of the mouse testis and provide a reliable transcriptome reference for this organ.

Age Factors↗

PubMed2004

Tissue distribution, biochemical properties, and transmission of mouse type A AApoAII amyloid fibrils.

In mouse strains with the amyloidogenic apolipoprotein A-II (ApoA-II) gene (Apoa2c), the type C ApoA-II protein (APOAIIC) associates to form amyloid fibrils AApoAII(C) that lead to development of early onset and systemic amyloidosis with characteristic heavy amyloid deposits in the liver and spleen. We found age-associated heavy deposition of amyloid fibrils [AApoAII(A)] composed of type A ApoA-II protein (APOAIIA) in BDF1 and C57BL/6 mice reared at one of our institutes. AApoAII(A) fibrils were deposited in the intestine, lungs, tongue, and stomach but not in the liver or spleen. AApoAII(A) fibrils were isolated, and morphological, biochemical, and structural characteristics distinct from those seen in AApoAII(C) and mouse AA amyloid fibrils were found. Transmission electron and atomic force microscopy showed that the majority of isolated AApoAII(A) amyloid fibrils featured fine, protofibril-like shapes. AApoAII(A) fibrils have a much weaker affinity for thioflavine T than for AApoAII(C), whereas APOAIIA protein contains less of the beta-pleated sheet structure than does APOAIIC. The injection of AApoAII(A) fibrils induced amyloid deposition in C57BL/6 and DBA2 mice (Apoa2a) as well as in R1.P1-Apoa2c mice (Apoa2c), but AApoAII(A) induced more severe amyloidosis in Apoa2a strains than in the Apoa2c strain. It was found that AApoAII(A) fibrils isolated from mice with mildly amyloidogenic APOAIIA protein have distinct characteristics. Induction of amyloidosis by heterologous amyloid fibrils clearly showed interactions between amyloid protein monomers and fibrils having different primary structures.

Alleles↗