Mode of Hydrolysis of Chitooligosaccharides with Pycnoporus cinnabarinus β-N-Acetylhexosaminidase: Application of High-Performance Liquid Chromatography

Recent epidemiological studies have demonstrated that high dietary consumption of fruit and vegetables results in lower risks of diabetes. In this study, we investigated the effects of chronic administration of fruit extract (Citrus unshiu Marc.) on glucose tolerance in GK rats, a model of type 2 diabetes. After 10 weeks administration of the fruit extract, intraperitoneal glucose tolerance tests revealed significant decrements of blood glucose levels after glucose loading. Our findings further support an advantageous association of fruit consumption with diabetes.     

Nucleotides modulate the activity of aspartate racemase of Scapharca broughtonii

The activity of -aspartate racemase purified from Scapharca broughtonii has been found to depend markedly on some nucleotides. Purine nucleoside monophosphates enhanced the enzyme activity, which was, on the contrary, lowered by purine nucleoside triphosphates and not affected by pyrimidine nucleotides. AMP produced the highest increase of seven-fold in the enzyme activity at 6 mM and a half-maximum increase at approximately 3.8 mM. ATP caused a half-maximum decrease in the activity at approximately 1.4 mM and the remaining activity was lower than 7% at saturating ATP concentrations. AMP and ATP both brought about changes in V_max and not in K_m. Analysis of the effect of AMP and ATP suggests that each of them has its own primary binding site, which is different from the substrate-binding site. In view of these effects of the nucleotides, the roles of the racemase and -aspartate in energy metabolism under anoxic conditions are discussed.     

Endogenous enzyme reactions closely related to photon emission in the plant defense response

Lipoxygenase (LOX) and peroxidase (POD) reactions, which are involved in the production of reactive oxygen and radical species, are shown to be associated with ultraweak photon emission in plant defense mechanisms. These enzyme reactions induced high-level ultraweak photon emission in an in vitro reaction system. The application of LOX to sweet potato slices caused photon emission directly in plants. LOX substrate promoted photon emission in chitosan-treated sweet potato, and LOX inhibitor markedly suppressed this emission. Therefore, a LOX-related pathway, including LOX and other downstream reactions, is principally associated with photon emission in plant defense mechanisms.     

Amino acid substitution of the largest subunit of yeast RNA polymerase II: effect of a temperature-sensitive mutation related to G1 cell cycle arrest

A mammalian temperature-sensitive mutant tsAF8 shows cell cycle arrest at nonpermissive temperatures in mid-G1 phase. DNA sequence comparison of the largest subunit of RNA polymerase II (Rpb1) from the wild-type and the mutant shows that the mutant phenotype results from a (hemizygous) C-to-A variation at nucleotide 944 in one rpb1 allele, giving rise to an Ala-to-Asp substitution at residue 315 in the protein. This amino acid substitution was introduced into the Schizosaccharomyces pombe rpb1 gene. Whereas tsAF8 cells showed growth defects and altered Rpb1 distribution at nonpermissive temperatures, yeast cells harboring this amino acid substitution did not show apparent temperature sensitivity. The effect of another temperature-sensitive Rpb1 mutation was also small. These results suggest that mutation of the rpb1 gene, which is critical in mammalian cells, may not be deleterious in yeast cells.     

Liver peroxisome proliferator-activated receptor gamma contributes to hepatic steatosis,triglyceride clearance,and regulation of body fat mass

Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor that mediates the antidiabetic effects of thiazolidinediones. PPAR gamma is present in adipose tissue and becomes elevated in fatty livers, but the roles of specific tissues in thiazolidinedione actions are unclear. We studied the function of liver PPAR gamma in both lipoatrophic A-ZIP/F-1 (AZIP) and wild type mice. In AZIP mice, ablation of liver PPAR gamma reduced the hepatic steatosis but worsened the hyperlipidemia, triglyceride clearance, and muscle insulin resistance. Inactivation of AZIP liver PPAR gamma also abolished the hypoglycemic and hypolipidemic effects of rosiglitazone, demonstrating that, in the absence of adipose tissue, the liver is a primary and major site of thiazolidinedione action. In contrast, rosiglitazone remained effective in non-lipoatrophic mice lacking liver PPAR gamma, suggesting that adipose tissue is the major site of thiazolidinedione action in typical mice with adipose tissue. Interestingly, mice without liver PPAR gamma, but with adipose tissue, developed relative fat intolerance, increased adiposity, hyperlipidemia, and insulin resistance. Thus, liver PPAR gamma regulates triglyceride homeostasis, contributing to hepatic steatosis, but protecting other tissues from triglyceride accumulation and insulin resistance.     

Mitochondrial haplogroup A is a genetic risk factor for atherothrombotic cerebral infarction in Japanese females

Mitochondrion-derived reactive oxygen species possibly play an important role in the pathogenesis of atherosclerosis and atherothrombotic cerebral infarction, because mitochondria in vascular endothelial cells are the major site of superoxide production. In the present study, we surveyed mitochondrial haplogroups associated with atherothrombotic cerebral infarction in 1081 Japanese subjects. Twenty-six mitochondrial single nucleotide polymorphisms of 11 major mitochondrial haplogroups (F, B, A, N9a, M7a, M7b, M7c, G1, G2, D4, and D5) were determined by use of 28-plex PCR and fluorescent beads combined with sequence-specific oligonucleotide probes. Multivariate logistic regression analysis with adjustment for conventional risk factors revealed that mitochondrial haplogroup A was associated with atherothrombotic cerebral infarction in female subjects (P< 0.05). However, no significant association was detected for males. Our study shows that haplogroup A confers an increased risk of atherothrombotic cerebral infarction in Japanese females. Validation of our findings will require additional studies with independent subject panels.     

Impact of Obstructive Sleep Apnea on Liver Fat Accumulation According to Sex and Visceral Obesity

Rationale

Associations between obstructive sleep apnea (OSA) and liver fat accumulation have been frequently investigated because both morbidities are common. Visceral fat was reported to be closely related to OSA and liver fat accumulation. Recently, sex differences in the association between OSA and mortality have gained much attention.

Objectives

To investigate the associations among OSA, liver fat accumulation as determined by computed tomography, and visceral fat area and their sex differences.

Methods

Studied were 188 males and 62 females who consecutively underwent polysomnography and computed tomography.

Results

Although the apnea-hypopnea index was positively correlated with liver fat accumulation in the total males, none of the OSA-related factors was independently associated with liver fat accumulation in either the total male or female participants in the multivariate analyses. When performing subanalyses using a specific definition for Japanese of obesity or visceral obesity (body mass index (BMI) ≥25 kg/m² or visceral fat area ≥100 cm²), in only males without visceral obesity, percent sleep time with oxygen saturation <90%, in addition to BMI, insulin resistance, and serum triglyceride values, was independently correlated with liver fat accumulation (R² = 15.1%, P<0.001). In males, percent sleep time of oxygen saturation <90% was also a determining factor for alanine aminotransferase values regardless of visceral fat area. In contrast, OSA was not associated with liver fat accumulation or alanine aminotransferase values in females whether or not visceral obesity was absent.

Conclusions

Sex differences in the visceral fat-dependent impact of OSA on liver fat accumulation existed. Although the mechanisms are not known and ethnic differences may exist in addition to the specific criteria of visceral obesity in Japan, the treatment of male patients with OSA might be favorable from the viewpoint of preventing liver fat accumulation and liver dysfunction even in patients without obvious visceral fat accumulation.     

Knee Pain and Low Back Pain Additively Disturb Sleep in the General Population: A Cross-Sectional Analysis of the Nagahama Study

Introduction

Association of knee and low back pain with sleep disturbance is poorly understood. We aimed to clarify the independent and combined effects of these orthopedic symptoms on sleep in a large-scale general population.

Methods

Cross-sectional data about sleep and knee/low back pain were collected for 9,611 community residents (53±14 years old) by a structured questionnaire. Sleep duration less than 6 h/d was defined as short sleep. Sleep quality and the presence of knee and low back pain were evaluated by dichotomous questions. Subjects who complained about knee or low back pains were graded by tertiles of a numerical response scale (NRS) score and a Roland-Morris disability questionnaire (RDQ) score respectively. Multivariate regression analyses were performed to determine the correlates of short sleep duration and poor sleep quality.

Results

Frequency of participants who complained of the orthopedic symptoms was as follows; knee pain, 29.0%; low back pain, 42.0% and both knee and low back pain 17.6%. Both knee and low back pain were significantly and independently associated with short sleep duration (knee pain: odds ratio (OR) = 1.19, p<0.01; low back pain: OR = 1.13, p = 0.01) and poor sleep quality (knee pain: OR = 1.22, p<0.01; low back pain; OR = 1.57, p<0.01). The group in the highest tertile of the NRS or RDQ score had the highest risk for short sleep duration and poor sleep quality except for the relationship between the highest tertile of the RDQ score and short sleep duration.(the highest tertile of the NRS: OR for short sleep duration = 1.31, p<0.01; OR for poor sleep quality = 1.47, p<0.01; the highest tertile of the RDQ: OR for short sleep duration = 1.11, p = 0.12; OR for poor sleep quality = 1.81, p<0.01) Further, coincident knee and low back pain raised the odds ratios for short sleep duration (either of knee or low back pain: OR = 1.10, p = 0.06; both knee and low back pain: OR = 1.40, p<0.01) and poor sleep quality (either of knee or low back pain: OR = 1.61, p<0.01; both knee and low back pain: OR = 2.17, p<0.01).

Conclusion

Knee and low back pains were independently associated with short sleep duration and poor sleep quality. Further, they additively increased the correlation with these sleep problems in the general population.