Pancreatic insulin secretory response and insulin action in heat-exposed sheep given a concentrate or roughage diet

The effects of heat exposure and type of diet on the insulin secretory response to glucose and glucose disposal in response to insulin action in female sheep were investigated employing hyperglycemic and euglycemic clamp techniques. Animals were divided into concentrate and roughage diet groups, and were maintained at the same intake levels of metabolizable energy and crude protein in both diets. Each diet group was subjected to either thermoneutral (20°C, 70% RH) or hot (30°C, 70% RH) environment, followed by glucose clamp experiments.

Heat-exposed sheep showed significant increases in respiration rates (P<.001) and rectal temperature (P<.05). Plasma glucose concentrations in the basal conditions were lower (P<.01) in the hot environment than in the thermoneutral environment, but there was no significant difference in basal levels of plasma insulin between the environmental treatments. In the hyperglycemic clamp experiment, mean plasma insulin increments increased (P<.05) during the heat exposure period across diet treatments. The ratio of mean plasma insulin increment to glucose infusion rate tended to be higher (P<.07) in the hot environment than in the thermoneutral environment, but diet treatment did not affect the ratio of mean plasma insulin increment to glucose infusion rate. The euglycemic clamp technique showed that glucose infusion rates remained unchanged among treatments. Insulin secretion response to glucose could be stimulated in the hot environment.     

Influences of genetic and environmental factors on the concentration of the allergen Cry j 1 in sugi (Cryptomeria japonica) pollen

Pollen from sugi (Japanese cedar, Cryptomeria japonica D. Don), a forest tree species that is widely grown in Japan, causes serious allergic disease. The major allergens from sugi pollen, Cry j 1 and Cry j 2, have been isolated and characterized. It has been reported that Cry j 1 concentration in pollen varies considerably among trees. If Cry j 1 concentration is genetically controlled, the planting of trees with low Cry j 1 concentrations would reduce pollinosis. We investigated genetic and environmental effects on Cry j 1 concentration in eight clones growing at four sites. Concentrations of Cry j 1 in pollen were measured with a monoclonal antibody-based Enzyme Linked Immunosorbent Assay (ELISA). The Cry j 1 concentrations differed significantly among clones and sites, but the site x clone interaction was not significant, suggesting that the Cry j 1 concentration is controlled primarily by genetic factors. We examined correlations between Cry j 1 concentration and temperature and precipitation from July through February. Temperature was not significantly related to Cry j 1 concentration, whereas cumulative precipitation during the 8 months and mean daily precipitation in September showed significant negative correlations with Cry j 1 concentration.     

New method to evaluate water-soluble antioxidant activity based on protein structural change

A simple method to evaluate antioxidant activities of water-soluble ingredients of foods has been developed. Protective effects of antioxidants against hypochlorite radical or hydroxyl radical have been studied by comparing changes in absorbance of myoglobin (a standard reference) at 409 nm. Protective ratio, defined by absorbance changes of myoglobin with or without the antioxidant, was a good indicator to quantitatively evaluate the antioxidant activity against the hypochlorite radical or the hydroxyl radical, respectively. Radar charts indicating the antioxidant activities against DPPH (1,1-diphenyl-2-picrylhydrazyl), hypochlorite radical, and hydroxyl radical clearly differentiated the characteristics of five antioxidants including carnosine, glutathione, and vitamin C. By comparison of the radar charts, antioxidant activity of bonito meat hydrolysate was found to have similar characteristics to that of carnosine. The simple method proposed in this study would be useful for evaluating and characterizing the activities of water-soluble antioxidants contained in various food materials.     

Combined effects of diet and cold exposure on insulin responsiveness to glucose and tissue responsiveness to insulin in sheep.

Hyperglycemic clamp and hyperinsulinemic euglycemic clamp techniques were used to investigate effects of diet and cold exposure on insulin responsiveness to glucose and tissue responsiveness and sensitivity to insulin in adult rams. The sheep were fed a high-concentrate diet (80% concentrate and 20% roughage) and a high-roughage diet (20% concentrate and 80% roughage), both 70% above the ME requirement for maintenance, and were exposed to a thermoneutral environment (20 degrees C) and a cold environment (0 degrees C) for 2 wk. The estimated ME intake was greater (P < .01) for the high-concentrate diet than for the high-roughage diet. In the hyperglycemic clamp experiment, the ratio of the plasma insulin increment to the glucose infusion rate (insulin responsiveness to glucose) was lower during cold exposure than in the thermoneutral environment in sheep fed the high-concentrate diet but was unchanged in sheep fed the high-roughage diet. In the hyperinsulinemic euglycemic clamp experiment, the glucose infusion rate (tissue responsiveness to insulin) was higher (P < .01) for the high-concentrate diet than for the high-roughage diet, and it was also higher (P < .01) during cold exposure than in the thermoneutral environment, indicating that tissue responsiveness to insulin was intensified in sheep fed the high-concentrate diet during cold exposure associated with the higher energy intake. These results suggest that both reduced insulin responsiveness and enhanced tissue responsiveness to insulin in sheep exposed to cold were dependent on the type of diet.     

Preparation and dynamic viscoelasticity characterization of alkali-solubilized collagen from shark skin

Alkali-solubilized collagens, prepared by alkali-acid extraction and alkali direct extraction (abbreviated AASC and ALSC, respectively), were characterized by dynamic viscoelastic measurement of collagen solution (10 mg/mL). The optimum preparative conditions in terms of yield and polypeptide size are as follows: for the alkali-acid extraction, a pretreatment with 0.5 or 1 M NaOH containing 15% Na(2)SO(4) within 5 days at 20 degrees C followed by the subsequent acid extraction, and for the alkaline direct extraction, a treatment with 0.5 M NaOH containing 10% NaCl at 4 degrees C for 20-30 days. A major portion of the polypeptide sizes of AASC and ALSC is composed of alpha chains (alpha1 and alpha2). Dynamic viscoelasticity of collagen solution was measured as a function of temperature. AASC showed a greater contribution of elastic behavior rather than viscous behavior. On the contrary, ALSC exhibits a stronger viscous behavior than elastic behavior.     

Estimation of genetic data and breeding values of traits related to wax production in <Emphasis Type="Italic">Rhus succedanea</Emphasis> L. clones using the REML/BLUP method

Rhus succedanea L. is cultivated in Japan for the wax that can be extracted from its fruits. We determined genetic data for specific traits associated with wax production (fruit number per cluster, FN, fruit weight, FW, number of clusters per area, CN, and wax content, WC) in five traditional cultivars and 13 newer clones. Data were collected over 4 years and alternate bearing was observed: 2001 and 2003 were years with high yields; in 2002 and 2004 yields were poor. The restricted maximum likelihood method was used to calculate (co)variance components for analysis. Broad sense heritability was estimated and ranged from low (FN and CN) to high (FW and WC) for the traits examined. There were positive genetic correlations between FW and WC and negative ones between FN and FW throughout the 4 years. Genetic correlations between CN and the other traits were positive in good crop years and negative in bad crop years. For each assessed clone, the four traits in the 4 years were evaluated using best linear unbiased predictors (BLUP) of the clonal breeding values. The BLUP scores for both FW and WC exhibited positive correlations between pairs of years, whereas there were positive BLUP correlations for CN when the high yield and low yield years were examined separately. The traditional cultivars and the newer clones were also characterized. Some of the clones were better than the traditional cultivars with regard to wax yield and reliability of production. The trait characteristics and the future breeding are discussed.     

Inhibition strength of short peptides derived from an ACE inhibitory peptide

A series of peptides, derived from an ACE inhibitory peptide (VTVNPYKWLP) found in our previous work, were synthesized. Their half maximal inhibition concentrations (IC(50)) for ACE inhibition have been determined. The effect of amino acid sequence on ACE inhibition was discussed on the basis of IC(50) of the synthetic peptides, and the following characteristics of the ACE inhibitory peptide have been clarified. First, the active portion of this peptide for ACE inhibition is KW. Second, the amino acid sequences near this dipeptide (KW) have a strong effect on the inhibitory activity. Especially, the proline residue in the C-terminal end strongly enhanced ACE inhibition. It should be noted that the IC(50) value of KWLP (5.5 μM) is the same as the ACE inhibitory peptide (VTVNPYKWLP) and that the IC(50) value of KW is 7.8 μM. The stability and absorption efficiency in vivo would be significantly improved by shortening the peptide length from 10 amino acids to four amino acids or two amino acids.     

Patient-side assay of lipase activity correlating with pancreatic lipase immunoreactivity in the dog

Pancreatitis is a common exocrine pancreatic disease in dogs, and the pancreatic lipase immunoreactivity (PLI) test is used for diagnosis. Enzyme catalytic assay is thought to have low specificity, but a lipase activity assay with increased specificity has been developed in human clinical chemistry. We measured serum lipase activity of 65 client-owned dogs using the newly developed FUJI DRI-CHEM slide and compared the results with their PLI concentrations. The results showed a good correlation (r = 0.91), and the normal and pancreatitis dogs identified based on the PLI values were correctly separated based on lipase activity. The present study suggests that FUJI DRI-CHEM lipase activity would be helpful for diagnosis of pacreatitis in dogs and, in particular, that it can be used as a patient-side assay and contributes to immediate treatment.     

Th2 immune responses and alternatively activated macrophages (AAMacs) in helminth infection in aged mice

This study aims to understand Th2 immune responses and alternative macrophage activation against nematode parasites in aged mice. Eighteen-month (18 M) and three-month (3 M) old C3H/HeN mice were inoculated with Heligmosomoides polygyrus (Hp) larvae. Real-time PCR analysis indicated that interleukin (IL)-4 and IL-13 gene expression was elevated in both groups after infection, but the expression level was significantly low in 18 M mice. Macrophage phenotype was monitored by measuring arginase-1 gene expression and immunofluorescence staining in small intestine, showing a decrease in the number of alternatively activated macrophages (AAMacs) around worm cysts in 18 M mice. These results suggest that the Th2 immune response in aged mice against a nematode parasite was not sufficiently induced to promote AAMacs.