Effect of Body Mass Index and Intra-Abdominal Fat Measured by Computed Tomography on the Risk of Bowel Symptoms

Background

This study aims to investigate the association between body mass index (BMI) or intra-abdominal fat measured by computed tomography (CT) and bowel symptoms.

Method

A cohort of 958 Japanese adults who underwent colonoscopy and CT and completed questionnaires after excluding colorectal diseases was analyzed. Six symptoms (constipation, diarrhea, loose stools, hard stools, fecal urgency, and incomplete evacuation) using a 7-point Likert scale were evaluated between baseline and second questionnaire for test-retest reliability. Associations between BMI, visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and symptom score were analyzed by a rank-ordered logistic model, adjusting for age, sex, smoking, and alcohol consumption, hypertension, diabetes mellitus, and dyslipidemia.

Results

Some bowel symptom scores were significantly (p<0.05) different between the age groups, sexes, smoking, and alcohol consumption. In multivariate analysis, constipation was associated with low BMI (p<0.01), low VAT area (p = 0.01), and low SAT area (p<0.01). Moreover, hard stools was associated with low BMI (p<0.01) and low SAT area (p<0.01). The remaining symptoms were not significantly associated with BMI or intra-abdominal fat. Test-retest reliability of bowel symptom scores with a mean duration of 7.5 months was good (mean kappa, 0.672).

Conclusions

Both low BMI and low abdominal fat accumulation appears to be useful indicators of increased risk for constipation and hard stools. The long-term test-retest reliability of symptom score suggests that bowel symptoms relevant to BMI or visceral fat remain consistent over several months.     

Ovarian germline stem cells in the teleost fish, medaka (Oryzias latipes)

In the mammalian testis germline stem cells keep producing many sperms, while there is no direct evidence for the presence of germline stem cells in the ovary. It is widely accepted in mammals that the mature oocytes are supplied from a pool of primordial follicles in the adult ovary. In other vertebrates, such as fish, however, there has been no investigation on the mechanism underlying the high egg-producing ability. In this review, we introduce the recently identified ovarian germline stem cells and the surrounding unique structure in teleost fish, medaka (Oryzias latipes) [Nakamura S et al. Science. 2010; 328: 1561-1563]. We also discuss about the expression and function of sox9 that characterizes this unique structure.     

Successful carnivore identification with faecal DNA across a fragmented Amazonian landscape

The use of scat surveys to obtain DNA has been well documented in temperate areas, where DNA preservation may be more effective than in tropical forests. Samples obtained in the tropics are often exposed to high humidity, warm temperatures, frequent rain and intense sunlight, all of which can rapidly degrade DNA. Despite these potential problems, we demonstrate successful mtDNA amplification and sequencing for faeces of carnivores collected in tropical conditions and quantify how sample condition and environmental variables influence the success of PCR amplification and species identification. Additionally, the feasibility of genotyping nuclear microsatellites from jaguar (Panthera onca) faeces was investigated. From October 2007 to December 2008, 93 faecal samples were collected in the southern Brazilian Amazon. A total of eight carnivore species was successfully identified from 71% of all samples obtained. Information theoretic analysis revealed that the number of PCR attempts before a successful sequence was an important negative predictor across all three responses (success of species identification, success of species identification from the first sequence and PCR amplification success), whereas the relative importance of the other three predictors (sample condition, season and distance from forest edge) varied between the three responses. Nuclear microsatellite amplification from jaguar faeces had lower success rates (15-44%) compared with those of the mtDNA marker. Our results show that DNA obtained from faecal samples works efficiently for carnivore species identification in the Amazon forest and also shows potential for nuclear DNA analysis, thus providing a valuable tool for genetic, ecological and conservation studies.     

Properties of gene knockdown system by vector‐based siRNA in zebrafish

RNA interference (RNAi) has emerged as a powerful tool to silence specific genes. Vector‐based RNAi systems have been developed to downregulate targeted genes in a spatially and temporally regulated fashion both in vitro and in vivo. The zebrafish (Danio rerio) is a model animal that has been examined based on a wide variety of biological techniques, including embryonic manipulations, forward and reverse genetics, and molecular biology. However, a heritable and tissue‐specific knockdown of gene expression has not yet been developed in zebrafish. We examined two types of vector, which produce small interfering RNA (siRNA), the direct effector in RNAi system; microRNA (miRNA) process mimicking vectors with a promoter for RNA polymerase II and short hairpin RNA (shRNA) expressing vector through a promoter for RNA polymerase III. Though gene‐silencing phenotypes were not observed in the miRNA process mimicking vectors, the transgenic embryos of the second vector (Tg(zU6‐shGFP)), shRNA expressing vector for enhanced green fluorescence protein, revealed knockdown of the targeted gene. Interestingly, only the embryos from Tg(zU6‐shGFP) female but not from the male fish showed the downregulation. Comparison of the quantity of siRNA produced by each vector indicates that the vectors tested here induced siRNA, but at low levels barely sufficient to silence the targeted gene.     

Interrelationships between mitochondrial fusion, energy metabolism and oxidative stress during development in Caenorhabditis elegans

Mitochondria are known to be dynamic structures with the energetically and enzymatically mediated processes of fusion and fission responsible for maintaining a constant flux. Mitochondria also play a role of reactive oxygen species production as a byproduct of energy metabolism. In the current study, interrelationships between mitochondrial fusion, energy metabolism and oxidative stress on development were explored using a fzo-1 mutant defective in the fusion process and a mev-1 mutant overproducing superoxide from mitochondrial electron transport complex II of Caenorhabditis elegans. While growth and development of both single mutants was slightly delayed relative to the wild type, the fzo-1;mev-1 double mutant experienced considerable delay. Oxygen sensitivity during larval development, superoxide production and carbonyl protein accumulation of the fzo-1 mutant were similar to wild type. fzo-1 animals had significantly lower metabolism than did N2 and mev-1. These data indicate that mitochondrial fusion can profoundly affect energy metabolism and development.     

Collagen-like polypeptide poly(Pro-Hyp-Gly) conjugated with Gly-Arg-Gly-Asp-Ser and Pro-His-Ser-Arg-Asn peptides enchances cell adhesion, migration, and stratification

Collagens are widely used in medical applications, including as a scaffold for tissue regeneration. However, animal-derived collagens have several drawbacks, such as low thermal stability, nonspecific cell adhesion, antigenicity, and contamination with pathogenic substances. To overcome these problems, we chemically synthesized the collagen-like polypeptide, poly(prolyl-hydroxyprolyl-glycyl) (poly(Pro-Hyp-Gly)), which forms a collagen-like triple-helical structure and shows biodegradability and biocompatibility. Here, we designed a novel scaffold where fibronectin-derived Gly Arg-Gly-Asp-Ser (GRGDS) and Pro-His-Ser-Arg-Asn (PHSRN) peptides were simultaneously conjugated with poly(Pro-Hyp-Gly). We assessed cell adhesion and migration activities using NIH3T3 cells in the scaffold and stratification ofimmortalized rabbit corneal epithelial cells. Cell adhesion was enhanced in scaffolds with GRGDS, increased with increasing amounts of conjugated GRGDS, and was significantly higher than bovine type I atelocollagen but lower than bovine fibronectin. Interestingly, simultaneous conjugation of GRGDS and PHSRN synergistically enhanced cell migration. Scaffolds containing almost equal amounts of GRGDS and PHSRN showed significantly higher cell migration than bovine type I atelocollagen. Addition of free GRGDS completely inhibited cell migration on the scaffold, whereas addition of free PHSRN partially inhibited cell migration. These results suggest that GRGDS plays a definitive role, and PHSRN plays an additional role, in cell migration. Conjugation of GRGDS resulted in the same level of stratification of rabbit corneal epithelial cells compared with bovine type I atelocollagen and bovine fibronectin. Because the simultaneous conjugation of GRGDS and PHSRN on poly(Pro-Hyp-Gly) enhances cell adhesion, migration, and stratification, it may be a useful scaffold for tissue regeneration.