Involvement of milk components in suppressing postprandial hyperglycemia induced by milk consumption

今回の研究では、乳糖分解乳、脱脂乳、乳たんぱく質水溶液を用いて、牛乳の飲用による米飯摂取後の血糖上昇抑制作用に対する牛乳中の成分の関与について検討した。12 時間以上の絶食をした健常な成人９名の空腹時血糖を測定した後、米飯と200 mL の試験飲料（牛乳、乳糖分解乳、脱脂乳乳たんぱく質水溶液）を摂取させ、摂取後120 分間の血糖値を経時的に測定した。併せて、各試験食摂取後120 分間の総血糖上昇量として血糖曲線下面積（AUC）をそれぞれ算出した。その結果、牛乳の飲用では米飯摂取後45～90 分目の血糖値及び総血糖上昇量が対照食（米飯＋蒸留水）摂取の場合よりも有意に低下した。しかし、乳糖分解乳、脱脂乳、乳たんぱく質水溶液の飲用では食後90 分目のみ血糖値の有意な低下が観察され、総血糖上昇量は対照食摂取での値と差がなかった。以上の結果より、牛乳の飲用で生じる米飯摂取後の血糖上昇抑制効果のうち、早い段階では乳中の脂質が、遅い段階では乳中のたんぱく質が関与することが示唆された。In the present study, we studied the role of cow milk components in suppressing postprandial hyperglycemia following the consumption of cooked rice along with whole milk, lactose-free milk, skim milk, and milk protein solution, respectively. Cooked rice and 200 mL of the test solution (lactose-free milk, skim milk, or milk protein solution) were administered to nine healthy participants after they had fasted for 12 h and had their fasting blood glucose levels monitored. Following the intake of cooked rice, the participants’ blood glucose levels were monitored over 120 min. Additionally, the area under the curve (AUC) values of the incremental blood glucose levels during this period were calculated. According to the findings, blood glucose levels at 45–90 min and the AUC after consuming cooked rice and whole milk together were significantly lower than those after consuming the control diet comprising cooked rice and distilled water. However, blood glucose levels were significantly reduced only 90 min after consuming lactose-free milk, skim milk, and milk protein solution with cooked rice, respectively, and the AUC values did not significantly differ from values following consumption of the controldepartmental bulletin pape

Memory Immune Responses against Pandemic (H1N1) 2009 Influenza Virus Induced by a Whole Particle Vaccine in Cynomolgus Monkeys Carrying Mafa-A1*052∶02

We made an H1N1 vaccine candidate from a virus library consisting of 144 ( = 16 HA×9 NA) non-pathogenic influenza A viruses and examined its protective effects against a pandemic (2009) H1N1 strain using immunologically naïve cynomolgus macaques to exclude preexisting immunity and to employ a preclinical study since preexisting immunity in humans previously vaccinated or infected with influenza virus might make comparison of vaccine efficacy difficult. Furthermore, macaques carrying a major histocompatibility complex class I molecule, Mafa-A1*052∶02, were used to analyze peptide-specific CD8+ T cell responses. Sera of macaques immunized with an inactivated whole particle formulation without addition of an adjuvant showed higher neutralization titers against the vaccine strain A/Hokkaido/2/1981 (H1N1) than did sera of macaques immunized with a split formulation. Neutralization activities against the pandemic strain A/Narita/1/2009 (H1N1) in sera of macaques immunized twice with the split vaccine reached levels similar to those in sera of macaques immunized once with the whole particle vaccine. After inoculation with the pandemic virus, the virus was detected in nasal samples of unvaccinated macaques for 6 days after infection and for 2.67 days and 5.33 days on average in macaques vaccinated with the whole particle vaccine and the split vaccine, respectively. After the challenge infection, recall neutralizing antibody responses against the pandemic virus and CD8+ T cell responses specific for nucleoprotein peptide NP262-270 bound to Mafa-A1*052∶02 in macaques vaccinated with the whole particle vaccine were observed more promptly or more vigorously than those in macaques vaccinated with the split vaccine. These findings demonstrated that the vaccine derived from our virus library was effective for pandemic virus infection in macaques and that the whole particle vaccine conferred more effective memory and broader cross-reactive immune responses to macaques against pandemic influenza virus infection than did the split vaccine

Identification and characterization of a dipeptidyl peptidase IV inhibitor from aronia juice

Aronia berries have many potential effects on health, including an antioxidant effect, effect for antimutagenesis, hepatoprotection and cardioprotection, an antidiabetic effect and inhibition of cancer cell proliferation. Previous human studies have shown that aronia juice may be useful for treatment of obesity disorders. In this study, we found that aronia juice has an inhibitory effect against dipeptidyl peptidase IV (DPP IV) (EC 3.4.14.5). DPP IV is a peptidase that cleaves the N-terminal region of incretins such as glucagon-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). Inactivation of incretins by DPP IV induces reduction of insulin secretion. Furthermore, we identified that cyanidin 3, 5-diglucoside as the DPP IV inhibitor in aronia juice. DPP IV was inhibited more strongly by cyanidin 3, 5-diglucoside than by cyanidin and cyanidin 3-glucoside. The results suggest that DPP IV is inhibited by cyanidin 3, 5-diglucoside present in aronia juice. The antidiabetic effect of aronia juice may be mediated through DPP IV inhibition by cyanidin 3, 5-diglucoside

Rapid and Simple Purification of Lysozyme from the Egg Shell Membrane

Lysozyme (EC 3.2.1.17) is a hydrolytic enzyme that cleaves the β-(1, 4)-glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycan, a major bacterial cell wall polymer. In the food industry, lysozyme is used as an additive mainly in the production of wine and beer. Lysozyme was found to be localized in the egg shell membrane. In this study, we found that lysozyme was easily purified from the egg shell membrane and that the enzyme also had an antibacterial activity. Furthermore, we found that the antibacterial activity of purified lysozyme from the egg shell membrane was lower than that of purified lysozyme from the egg white at alkaline pH. The method for rapid purification of lysozyme developed in this study should contribute to food industry

Knockdown of legumain inhibits cleavage of annexin A2 in the mouse kidney

Legumain (EC 3.4.22.34) is an asparaginyl endopeptidase. Strong legumain activity was observed in the mouse kidney, and legumain was highly expressed in tumors. We previously reported that bovine kidney annexin A2 was co-purified with legumain and that legumain cleaved the N-terminal region of annexin A2 at an Asn residue in vitro. In this study, to determine whether annexin A2 is cleaved by legumain in vivo, siRNA-lipoplex targeting mouse legumain was injected into mouse tail veins. Mouse kidneys were then isolated and the effect of knockdown of legumain expression on annexin A2 cleavage was examined. The results showed that both legumain mRNA and protein expression levels were decreased in the siRNA-treated mouse kidneys and that legumain activity toward a synthetic substrate, Z-Ala-Ala-Asn-MCA, was decreased by about 40% in the kidney but not in the liver or spleen. Furthermore, cleavage of annexin A2 at the N-terminal region was decreased in the mouse kidney that had been treated with the legumain siRNA-lipoplex. These results suggest that legumain siRNA was delivered to the kidney by using LipoTrust and that the reduced legumain expression inhibited legumain-induced degradation of annexin A2 in vivo. (C) 2012 Elsevier Inc. All rights reserved

Transcriptional regulation of the legumain gene by p53 in HCT116 cells

Legumain (EC 3.4.22.34) is an asparaginyl endopeptidase. Strong legumain activity was observed in the mouse kidney, and legumain was found to be highly expressed in tumors. We previously reported that bovine kidney annexin A2 was co-purified with legumain and that legumain cleaved the N-terminal region of annexin A2 at an Asn residue in vitro and in vivo. In this study, we found a p53-binding site in intron 1 of the human legumain gene using computational analysis. To determine whether transcription of the legumain gene is regulated by p53, HCT116 cells were transfected with p53 siRNA and the effect of knockdown of p53 expression on legumain expression was examined. The results showed that expression levels of both legumain mRNA and protein were decreased in the siRNA-treated cells. Furthermore, enzyme activity of legumain was also increased by doxorubicin and its activity was reduced by knockdown of p53 in HCT116 cells. These results suggest that legumain expression and its enzyme activity are regulated by p53. (C) 2013 Elsevier Inc. All rights reserved