Age Difference in Morphology and Immunohistology inthe Thymus and Spleen in Crl:CD (SD) Rats

We investigated chronological changes in immunohistochemical phenotyping in the thymus and spleen in Crl:CD rats up to the age of about one year. In the thymus, T cells increased markedly from 3 to 4 weeks of age. Proliferating cells also increased markedly at these points. B cells tended towards an increase with age. In the spleen, white pulp increased until 9 weeks of age and remained fairly stable thereafter. In the periarteriolar lymphoid sheath and marginal zone, T cells gradually increased until 9 weeks of age and became almost flat thereafter. In the lymph follicle, T cells increased with age. B cells tended towards an increase with age in all areas of the spleen. It was concluded that development of the thymus was most marked from 3 to 4 weeks of age and that both the thymus and spleen had matured by 9 weeks of age.     

Mitigation of pyrexia by a Th-1-biased IgG subclass response after infection with equine herpesvirus type 1 in horses pre-immunized with inactivated vaccine

The immunoglobulin G (IgG) subclass response was investigated in horses with or without pyrexia after natural infection with equine herpesvirus type 1 (EHV-1) in the field. All horses were kept at the training centers of the Japan Racing Association and were immunized with an inactivated EHV-1 vaccine before EHV-1 infection. An IgG subclass response dominated by IgGa and IgGb was induced in horses without pyrexia after EHV-1 infection. In contrast, horses that developed pyrexia showed increased IgGc and IgG (T) subclass production in addition to IgGa and IgGb. Although inactivated EHV-1 vaccines are considered to induce a mainly Th-2-biased response, these results indicated that the responses in horses inoculated with inactivated EHV-1 vaccine were not uniform, and that horses with a Th-1-biased response were likely to be protected from pyrexia.     

Experimental hyperlipemia induces insulin resistance in cats

The effect of experimental hyperlipemia on insulin sensitivity was evaluated in seven healthy cats. Serum triglyceride and free fatty acid concentrations were significantly (P<0.05) higher when lipid-heparin was administered (2,894 ± 1,526 mg/dl and 4.54 ± 0.70 mEq/l, respectively) than when saline was administered (70 ± 42 mg/dl and 0.22 ± 0.08 mEq/l, respectively). A glucose clamp test revealed that the mean glucose infusion rate when lipid-heparin was administered (5.80 ± 0.67 mg/kg/min) was significantly (P<0.05) lower than when saline was administered (8.52 ± 1.83 mg/kg/min). These results suggest that experimental hyperlipemia induced insulin resistance in the healthy cats.     

Comparing the osteogenic potential of canine mesenchymal stem cells derived from adipose tissues, bone marrow, umbilical cord blood, and Wharton's jelly for treating bone defects

Alternative sources of mesenchymal stem cells (MSCs) for replacing bone marrow (BM) have been extensively investigated in the field of bone tissue engineering. The purpose of this study was to compare the osteogenic potential of canine MSCs derived from adipose tissue (AT), BM, umbilical cord blood (UCB), and Wharton''s jelly (WJ) using in vitro culture techniques and in vivo orthotopic implantation assays. After canine MSCs were isolated from various tissues, the proliferation and osteogenic potential along with vascular endothelial growth factor (VEGF) production were measured and compared in vitro. For the in vivo assay, MSCs derived from each type of tissue were mixed with β-tricalcium phosphate and implanted into segmental bone defects in dogs. Among the different types of MSCs, AT-MSCs had a higher proliferation potential and BM-MSCs produced the most VEGF. AT-MSCs and UCB-MSCs showed greater in vitro osteogenic potential compared to the other cells. Radiographic and histological analyses showed that all tested MSCs had similar osteogenic capacities, and the level of new bone formation was much higher with implants containing MSCs than cell-free implants. These results indicate that AT-MSCs, UCB-MSCs, and WJ-MSCs can potentially be used in place of BM-MSCs for clinical bone engineering procedures.     

Dynamic response of wall-floor joints of wooden light-frame constructions under forced harmonic vibrations

Shaking table tests of the wall-floor joints of wooden light-frame constructions under forced harmonic vibrations are conducted in this study so as to observe the dynamic responsive characteristics. The principal results are as follows: The responsive characteristics of timber constructions under strong earthquakes cannot be directly correlated with their resonant frequencies under free or forced vibrations with low input accelerations, because they behave as continuous bodies when the input accelerations are less than the apparent frictional limits of structural joints. The apparent frictional limits are reduced by periodic fluctuation of the effective vertical loads as a result of the vertical motion of the specimens. The characteristic dynamic responses of wall-floor joints depend clearly upon the frequency and input accelerations of forced vibrations. These dependencies arise from the nonlinear load-slip relationship of the wall-floor joints. The equivalent stiffness in their successive transient phases decreases as joint slip increases, which gradually changes the resonant frequencies of the wall-floor joints. This indicates that the frequency components dominant to ultimate or safety-limit resistance should be distinguished from those dominant to allowable or serviceability-limit resistance.     

Risk assessment of ozone impact on <Emphasis Type="Italic">Fagus crenata</Emphasis> in Japan: consideration of atmospheric nitrogen deposition

Tropospheric ozone (O₃) is considered to be the air pollutant relating to the decline of Fagus crenata forest in Japan. In the present study, we assessed a risk of O₃ impact on the growth of F. crenata in Japan, giving consideration to the effects associated with atmospheric nitrogen (N) deposition based on the experimental study, national monitoring data for oxidant concentration and atmospheric N deposition, and a national vegetation survey. The average and maximum O₃-induced relative growth reduction (RG_red) of F. crenata across Japan were estimated to be 3.2 and 9.7%, respectively. Current levels of atmospheric N deposition were found to significantly affect the sensitivity of F. crenata to O₃. When the N deposition was assumed as zero, the estimated average and maximum RG_red were 2.3% and 5.7%, respectively. The inclusion of atmospheric N deposition data thus increased the estimated values for average and maximum RG_red (by 38% and 71%, respectively). Our results demonstrate that a change in the sensitivity to O₃ associated with atmospheric N deposition is an important consideration in the risk assessment of O₃ impact on the growth of F. crenata in Japan.     

Effects of intravenous ghrelin injection on plasma growth hormone,insulin and glucose concentrations in calves at weaning

Ghrelin action, which stimulates growth hormone (GH) secretion, may alter during the weaning period in calves. Our objective was to compare the effects of intravenous ghrelin injection on plasma GH, insulin and glucose concentrations in calves around the weaning period. Four Holstein bull calves were fed whole milk and allowed free access to solid feeds, and weaned at 7 weeks of age. Measurements were performed at weeks 1, 2, 4, 6, 7, 9, 11 and 13, when calves were intravenously injected with ghrelin (1.0 μg/kg body weight (BW)) through a catheter, and jugular blood samples were obtained temporally relative to the injection time. Estimated digestible energy intake per metabolic BW transiently decreased at week 7 because of low solid intake immediately after weaning, and thereafter gradually increased. Plasma insulin and glucose concentrations were not affected by ghrelin injection at all ages. In contrast, plasma GH concentrations increased with ghrelin injection at all ages. The incremental area of GH at week 7 was greatest and significantly higher compared with weeks 2, 4, 6 and 9. This result suggests that nutrient insufficiency immediately after weaning enhances GH responsiveness to ghrelin.