Anti-prediabetic effect of rose hip (Rosa canina) extract in spontaneously diabetic Torii rats.

BACKGROUND: Prediabetes, a high-risk state for developing diabetes showing impaired glucose tolerance but a normal fasting blood glucose level, has an increasing prevalence worldwide. However, no study investigating the prevention of impaired glucose tolerance at the prediabetic stage by anti-diabetic functional foods has been reported. Thus, the present study aimed to evaluate the anti-prediabetic effect of rose hip in a prediabetic rat model. RESULTS: Spontaneously diabetic Torii (SDT) rats were supplemented with hot-water extract of rose hip at a dose of 100 mg kg-1 body weight day-1 for 12 weeks. The results obtained showed that the supplementation of rose hip extract improved impaired glucose tolerance, promoted insulin secretion, preserved pancreatic beta-cell function and suppressed plasma advanced glycation end-products formation of methylglyoxal-derived hydroimidazolone (MG-H1) residue and Nϵ -carboxymethyl-lysine residues (e.g. MG-H1, control: 465.5 ± 43.8 versus rose hip: 59.1 ± 13.0 pmol mg protein-1 , P < 0.05) in SDT rats at the prediabetic stage (12-20 weeks old). CONCLUSION: The present study provides the first evidence showing that a hot-water extract of rose hip could exert an anti-prediabetic effect in a rat model. © 2017 Society of Chemical Industry.

Geranylgeraniol enhances testosterone production via the cAMP/protein kinase A pathway in testis-derived I-10 tumor cells.

Testosterone levels in men decrease with age; this decline has been linked to various diseases and can shorten life expectancy. Geranylgeraniol (GGOH) is an isoprenoid found in plants that plays an important role in several biological processes; however, its role in steroidogenesis is unknown. Here, we report that GGOH enhances the production of testosterone and its precursor progesterone in testis-derived I-10 tumor cells. GGOH induced protein kinase A (PKA) activity and increased cAMP levels and was found to regulate cAMP/PKA signaling by activating adenylate cyclase without altering phosphodiesterase activity. GGOH also stimulated mRNA and protein levels of steroidogenic acute regulatory protein, a downstream effector in the cAMP/PKA pathway. These results demonstrate that GGOH enhances steroidogenesis in testis-derived cells by modulating cAMP/PKA signaling. Our findings have potential applications for the development of therapeutics that increase testosterone levels in aging men.

Functional engineering of human iPSC-derived parasympathetic neurons enhances responsiveness to gastrointestinal hormones.

Food-derived biological signals are transmitted to the brain via peripheral nerves through the paracrine activity of gastrointestinal (GI) hormones. The signal transduction circuit of the brain-gut axis has been analyzed in animals; however, species-related differences and animal welfare concerns necessitate investigation using in vitro human experimental models. Here, we focused on the receptors of five GI hormones (CCK, GLP1, GLP2, PYY, and serotonin (5-HT)), and established human induced pluripotent stem cell (iPSC) lines that functionally expressed each receptor. Compared to the original iPSCs, iPSCs expressing one of the receptors did not show any differences in global mRNA expression, genomic stability, or differentiation capacities of the three germ layers. We induced parasympathetic neurons from these established iPSC lines to assess vagus nerve activity. We generated GI hormone receptor-expressing neurons (CCKAR, GLP1R, and NPY2R-neuron) and tested their responsiveness to each ligand using Ca2+ imaging and microelectrode array recording. GI hormone receptor-expressing neurons (GLP2R and HTR3A) were generated directly by gene induction into iPSC-derived peripheral nerve progenitors. These receptor-expressing neurons promise to contribute to a better understanding of how the body responds to GI hormones via the brain-gut axis, aid in drug development, and offer an alternative to animal studies.

[Establishment of a cut-off value for the diagnosis of acute myocardial infarction using a new CK-MB activity measurement reagent containing anti-MtCK antibody].

CK-MB is an important marker for the diagnosis of acute myocardial infarction (AMI). Since mitochondrial CK (MtCK) is universally present in the blood of healthy individuals, it is known to positively affect the measurement of CK-MB using the immunoinhibition method, causing false-positive results. We performed basic evaluation of ACCURAS AUTO CK-MB MtO, a new reagent containing anti-MtCK antibody that inhibits MtCK activity, and attempted to calculate a cut-off CK-MB level to diagnose AMI. The measurement was performed in samples submitted to the Clinical Laboratory of our center for the measurement of CK-MB. This method was confirmed to have satisfactory basic attributes concerning the reproducibility, linearity, lower detection limit, and effects of interfering substances. When 2886 samples were examined using this and conventional methods, the results of the two methods were correlated in some but not in others. In the samples that showed no correlation, MtCK was demonstrated by isozyme analysis using electrophoresis. The AUC calculated from the ROC curve in AMI patients was 0.912 with this method and 0.861 with the conventional method. The sensitivity and specificity of the new method were higher than those of the conventional method. The cut-off value determined by ROC analysis was 7.7 U/l using the new method and 13.6 U/l using the conventional method, causing an increase in false-positive results compared with the cut off value of 25 U/l widely used for the conventional method to date. However, the cut-off value for the new method that yielded a specificity comparable to 99.1%, which is the specificity of the conventional method using a cut-off value of 25 U/l, was 12 U/l. With a cut-off value of 12 U/l, the sensitivity was improved compared with that employing the conventional method, and both the sensitivity and specificity became comparable to those of the CK-MB mass method. This method is very useful for the accurate measurement of CK-MB activity.

Serum Levels of Protein-Bound Methylglyoxal-Derived Hydroimidazolone-1 are Independently Correlated with Asymmetric Dimethylarginine.

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase, being involved in endothelial dysfunction. Furthermore, ADMA levels have been shown to predict future cardiovascular events in patients with coronary risk factors, such as diabetes and hypertension. We have previously found that glyceraldehyde-derived advanced glycation end products (glycer-AGEs) stimulate ADMA generation in vitro and the levels are associated with ADMA, endothelial dysfunction, and vascular inflammation in humans. However, it remains unclear what structurally distinct glycer-AGEs are independent correlates of ADMA. In this study, we addressed the issue. We measured serum levels of protein-bound and free methylglyoxal-derived hydroimidazolone-1 (MG-H1) and argpyrimidine, two major structurally identified glycer-AGEs by liquid chromatography-tandem mass spectrometry in 128 outpatients, and examined the correlations of these AGEs, vascular stiffness, and inflammation with ADMA. Moreover, we examined whether the changes in serum MG-H1 and argpyrimidine levels after 4-month treatment with oral hypoglycemic agents (OHAs) were associated with those of ADMA in other 44 patients with impaired glucose tolerance or type 2 diabetes. Multiple stepwise regression analysis revealed that protein-bound MG-H1, high-density lipoprotein cholesterol (inversely), high-sensitivity C-reactive protein, and cardio-ankle vascular index were independently correlated with ADMA (R2 = 0.259). Treatment with OHAs significantly decreased ADMA levels in 44 glucose-intolerant or type 2 diabetic patients, and the changes in protein-bound MG-H1 levels were positively associated with those in ADMA values (p < 0.05). This study demonstrates that serum levels of protein-bound MG-H1 are independently correlated with ADMA and may be a therapeutic target for cardiovascular disease.

Methylglyoxal-derived hydroimidazolone residue of plasma protein can behave as a predictor of prediabetes in Spontaneously Diabetic Torii rats.

Prediabetes, typically defined as impaired glucose tolerance and/or impaired fasting blood glucose, is a high-risk state of developing diabetes. The association of diabetes-related metabolites with prediabetes has not been investigated intensively. This study aimed to get insights into the metabolic behaviors of some typical diabetes-related metabolites in plasma of male Spontaneously Diabetic Torii (SDT) rats during pathogenic progress of diabetes and to assess in vivo if the variation in these metabolites related to the progression of prediabetic stage. To address this question, SDT rats and Sprague Dawley (SD) rats as control were maintained from the age of 7 to 25 weeks. Five typical advanced glycation end products (AGEs) residue of plasma protein and their free adducts were determined by liquid chromatography with tandem mass detection over the duration of the investigation. The SDT rats exhibited impaired glucose tolerance since the age of 12 weeks and developed diabetes with significantly elevated fasting glucose levels after 22 weeks. At the prediabetic stage (12-21 weeks), no significant differences were observed on AGE-free adducts levels of SDT rats compared with SD rats. However, methylglyoxal-derived hydroimidazolone (MG-H1) residue contents of plasma protein were significantly elevated in SDT rats at the age of 16 weeks, whereas other AGE residues of plasma protein did not show marked difference. The present study has revealed significant increase in MG-H1 residue content of plasma protein at the prediabetic stage of a spontaneously diabetic rat model, irrespective of unaltered fasting blood glucose and constant plasma levels of other AGEs.

Determination of peroxyl radical scavenging activity of flavonoids and plant extracts using an automatic potentiometric titrator.

A novel potentiometric method for evaluation of peroxyl radical scavenging activity of flavonoids and plant extracts was developed. The oxidation of potassium iodide (KI) was performed in acetonitrilephosphate buffer (1:1) containing antioxidant using 2,2'-azobis(2-amidinopropane) dihydrochloride as a peroxyl radical generator. The amount of iodine released from KI during a 20-min free radical oxidation was determined quantitatively using an automatic potentiometric titrator with sodium thiosulfate. The radical scavenging activity of the sample was expressed as the inhibition ratio for iodine release of the control group mediated by the radical. The results obtained from some authentic polyphenols correlated well with those of previous reports. This is a simple, time-saving method requiring less than 30 min and is useful in assessing the radical scavenging activity of antioxidants in plant extracts. We describe the radical scavenging activities of various flavonoids including 21 kinds of tea catechins and vegetable extracts by this method.

Epimerization of tea catechins and O-methylated derivatives of (-)-epigallocatechin-3-O-gallate: relationship between epimerization and chemical structure.

Epimerization at C-2 of O-methylated catechin derivatives and four major tea catechins were investigated. The epimeric isomers of (-)-epicatechin (I), (-)-epicatechin-3-O-gallate (II), (-)-epigallocatechin (III), (-)-epigallocatechin-3-O-gallate (IV), and (-)-epigallocatechin-3-O-(3-O-methyl)gallate (V) in green tea extracts increased time-dependently at 90 degrees C. The epimerization rates of authentic tea catechins in distilled water are much lower than those in tea infusion or in pH 6.0 buffer solution. The addition of tea infusion to the authentic catechin solution accelerated the epimerization, and the addition of ethylenediaminetetraacetic acid, disodium salt (Na(2)EDTA) decreased the epimerization in the pH 6.0 buffer solution. Therefore, the metal ions in tea infusion may affect the rate of epimerization. The proportions of the epimers to authentic tea catechins [III, IV, V, and (-)-epigallocatechin-3-O-(4-O-methyl)gallate (VI)] in pH 6.0 buffer solution after heating at 90 degrees C for 30 min were 42.4%, 37.0%, 41.7%, and 30.4%, respectively. These values were higher than those of I and II (23.5% and 23.6%, respectively). The O-methylated derivatives at the 4'-position on the B ring of IV and VI were hardly epimerized. These results suggest that the hydroxyl moiety on the B ring of catechins plays an important role in the epimerization in the order 3',4',5'-triol type > 3',4'-diol type >> 3',5'-diol type.

Virulence genes, quinolone and fluoroquinolone resistance, and phylogenetic background of uropathogenic Escherichia coli strains isolated in Japan.

A total of 312 uropathogenic Escherichia coli strains were isolated from clinical specimens in 7 hospitals in Aichi Prefecture, Japan. Among them, 113 strains were resistant to quinolone, and 49 strains were resistant to fluoroquinolone. Phylogenetic group B2 was most prevalent in both susceptible strains (148 of 199 strains, 74.4%) and resistant strains (quinolone-resistant strains, 73 of 113 strains, 64.6%; fluoroquinolone-resistant strains, 40 of 49 strains, 81.6%). The resistant strains showed a significantly lower prevalence of virulence genes papA, hlyA, and cnf1 than did the susceptible strains, and this observation was further obvious when compared within B2 group strains. Among the 40 fluoroquinolone-resistant strains belonging to group B2, 37 (92.5%) strains carried PAIusp subtype IIa, 36 strains of which carried E84V mutation in parC, whereas none of the 9 strains belonging to group D carried PAIusp subtype IIa, and only one strain carried the mutation. These observations indicate that the differences of phenotypes including resistance of quinolone and carriage of virulence genes are associated with the complex context of genetic background, including the phylogenetic group and PAIusp subtype.