To evaluate the role of dietary factors in the etiology of inflammatory bowel disease (IBD), we conducted a multicenter hospital-based case-control study in a Japanese population. Cases were IBD patients aged 15 to 34 years [ulcerative colitis (UC) 111 patients; Crohn's disease (CD) 128 patients] within 3 years after diagnosis in 13 hospitals. One control subject was recruited for each case who was matched for sex, age, and hospital. A semiquantitative food frequency questionnaire was used to estimate preillness intakes of food groups and nutrients. All the available control subjects (n = 219) were pooled, and unconditional logistic models were applied to calculate odds ratios (ORs). In the food groups, a higher consumption of sweets was positively associated with UC risk [OR for the highest versus lowest quartile, 2.86; 95% confidence interval (CI), 1.24 to 6.57], whereas the consumption of sugars and sweeteners (OR, 2.12; 95% CI, 1.08 to 4.17), sweets (OR, 2.83; 95% CI, 1.38 to 5.83), fats and oils (OR, 2.64; 95% CI, 1.29 to 5.39), and fish and shellfish (OR, 2.41; 95% CI, 1.18-4.89) were positively associated with CD risk. In respect to nutrients, the intake of vitamin C (OR, 0.45; 95% CI, 0.21 to 0.99) was negatively related to UC risk, while the intake of total fat (OR, 2.86; 95% CI, 1.39 to 5.90), monounsaturated fatty acids (OR, 2.49; 95% CI, 1.23 to 5.03) and polyunsaturated fatty acids (OR, 2.31; 95% CI, 1.12 to 4.79), vitamin E (OR, 3.23; 95% CI, 1.45 to 7.17), and n-3 (OR, 3.24; 95% CI, 1.52 to 6.88) and n-6 fatty acids (OR, 2.57; 95% CI, 1.24 to 5.32) was positively associated with CD risk. Although this study suffers from the shortcoming of recall bias, which is inherent in most retrospective studies (prospective studies are warranted to confirm the associations between diet and IBD risk), the present findings suggest the importance of dietary factors for IBD prevention.

Compared with findings in Western countries, the prevalence of reflux esophagitis in Oriental countries is estimated to be low. In this prospective study, we aimed to examine the proportion of reflux esophagitis in Japanese adults, as evaluated by endoscopy. Endoscopists were prospectively directed to grade esophageal mucosal breaks with esophagitis according to the Los Angeles Classification of Esophagitis in all subjects that underwent endoscopic examination. In total, 6010 subjects underwent endoscopic examination for evaluation of esophagitis grading from December 1996 to February 1998. The subjects included 4394 outpatients who were not receiving medication for gastrointestinal disease and 1616 subjects who visited the hospital for routine physical examinations. The overall proportion of esophagitis was 16.3%. Most of the subjects with esophagitis were classified as having grade A or B (proportion of grades A and B, 9.6% and 4.6%, respectively). The age-related proportion of esophagitis and of severe esophagitis (i.e., grades C and D) increased in females aged over 70 and in males aged over 80. Increased body mass index (partly due to decreased height caused by osteoporosis), and/or hiatal herniation, were related to the proportion of esophagitis in females aged over 70. These data indicated that reflux esophagitis is a common disease in Japan. However, severe esophagitis (grades C and D) is not common.

The molecular bases of circadian clocks have been studied in animals, fungi, bacteria, and plants, but not in eukaryotic algae. To establish a new model for molecular analysis of the circadian clock, here we identified a large number of components of the circadian system in the eukaryotic unicellular alga Chlamydomonas reinhardtii by a systematic forward genetic approach. We isolated 105 insertional mutants that exhibited defects in period, phase angle, and/or amplitude of circadian rhythms in bioluminescence derived from a luciferase reporter gene in their chloroplast genome. Simultaneous measurement of circadian rhythms in bioluminescence and growth rate revealed that some of these mutants had defects in the circadian clock itself, whereas one mutant had a defect in a specific process for the chloroplast bioluminescence rhythm. We identified 30 genes (or gene loci) that would be responsible for rhythm defects in 37 mutants. Classification of these genes revealed that various biological processes are involved in regulation of the chloroplast rhythmicity. Amino acid sequences of six genes that would have crucial roles in the circadian clock revealed features of the Chlamydomonas clock that have both partially plant-like and original components. The molecular bases of circadian clocks have been studied in animals, fungi, bacteria, and plants (Dunlap 1999;Harmer et al. 2001). Despite the striking biochemical features of circadian clocks (e.g., oscillation with long periodicity [∼24 h] and its temperature compensation) (Bünning 1973), their central components are not conserved between these kingdoms (Dunlap 1999;Harmer et al. 2001). To understand the nature of oscillation mechanisms and the evolutionary history of clock components, it is important to understand circadian clock systems of a wide range of organisms.Circadian rhythms of unicellular algae have been studied extensively (Mittag 2001), but no clock component of eukaryotic algae has yet been identified. Chlamydomonas reinhardtii is one of the best-studied algae in circadian rhythm research. A forward genetic approach to identify circadian clock components of Chlamydomonas was started more than three decades ago (Bruce 1970). Although several clock mutants have been isolated (Bruce 1972(Bruce , 1974Mergenhagen 1984), the genes responsible could not be identified because of limitations of tools for genetic analyses. However, since Chlamydomonas is now one of the most attractive model organisms in molecular genetics (Harris 2001), it is possible to re-establish it as a model for studying the molecular mechanism of the circadian clock. For this purpose, we previously developed bioluminescence reporter strains with a codon-optimized luciferase gene in their chloroplast genomes to enable real-time monitoring of circadian rhythms (Breton and Kay 2006;Matsuo et al. 2006).In this study, we screened ∼16,000 insertional mutants for defects in circadian rhythmicity of the chloroplast bioluminescence reporter, isolated 105 mutants, and identified 30 genes (or gene loci...

Cyanobacteria are the only bacterial species found to have a circadian clock. We used DNA microarrays to examine circadian expression patterns in the cyanobacterium Synechocystis sp. strain PCC 6803. Our analysis identified 54 (2%) and 237 (9%) genes that exhibited circadian rhythms under stringent and relaxed filtering conditions, respectively. The expression of most cycling genes peaked around the time of transition from subjective day to night, suggesting that the main role of the circadian clock in Synechocystis is to adjust the physiological state of the cell to the upcoming night environment. There were several chromosomal regions where neighboring genes were expressed with similar circadian patterns. The physiological functions of the cycling genes were diverse and included a wide variety of metabolic pathways, membrane transport, and signal transduction. Genes involved in respiration and poly(3-hydroxyalkanoate) synthesis showed coordinated circadian expression, suggesting that the regulation is important for the supply of energy and carbon source in the night. Genes involved in transcription and translation also followed circadian cycling patterns. These genes may be important for output of the rhythmic information generated by the circadian clock. Our findings provided critical insights into the importance of the circadian clock on cellular physiology and the mechanism of clock-controlled gene regulation.Circadian rhythm is a self-sustaining oscillation whose period length coincides with the 24-h day-night cycle. Many biological activities show circadian patterns, allowing organisms to adapt to daily fluctuations in the environment. Circadian rhythms are widespread and involve functions as diverse as human sleep-wake cycles and cyanobacterial nitrogen fixation. The molecular basis of circadian rhythms involves negative and positive feedback regulation of clock genes (16).Cyanobacteria are the only bacterial species found to have a circadian clock. Three clock genes, kaiA, kaiB, and kaiC, have been identified in Synechococcus sp. strain PCC 7942 (25). kaiB and kaiC form an operon and are coordinately transcribed, while kaiA is transcribed independently. All of the kai genes show circadian rhythms of expression. Continuous overexpression of kaiC represses expression of kaiBC, but overexpression of kaiA enhances expression of kaiBC. This suggests that kaiC is regulated by a negative feedback autoregulatory loop and that KaiA activates kaiBC expression, thus sustaining the cyclical expression of kaiBC (25).In cyanobacteria, activities as diverse as cell division, amino acid uptake, nitrogen fixation, respiration, and carbohydrate synthesis are under circadian control (18), but a clear mechanistic link between physiological rhythms and the regulation of output genes is still lacking. Promoter trap analyses were performed with two cyanobacterial species, Synechococcus sp. strain PCC 7942 (33) and Synechocystis sp. strain PCC 6803 (4). The percentage of rhythmic clones was lower in Synechocystis organisms (77...

This study aimed to evaluate the correlation between symptoms and endoscopic findings in reflux esophagitis. Subjects, 8031 persons without medication for gastrointestinal disease, were briefly asked about the presence of heartburn, dysphagia, odynophagia, and acid regurgitation by associated medical staff before endoscopy for assessment of esophagitis utilizing the Los Angeles Classification. Endoscopically, 1199 (14.9%) were classified as positive reflux esophagitis, and 2223 (27.7%) had heartburn, 1522 (19.0%) had dysphagia, 493 (6.1%) had odynophagia, and 1466 (18.3%) had acid regurgitation. Multivariate analysis indicated that the symptom most related to esophagitis was heartburn (odds ratio: 2.46), although approximately 40% of subjects with grade C or D did not complain of heartburn. Regarding the other symptoms, less than 30% subjects with severe esophagitis complained of the symptoms and the odds ratio was approximately 1. These results indicate that endoscopic esophagitis was not equivalent to any reflux symptoms from which subjects suffered in their daily lives.

Advanced colorectal cancer harbors extensive intratumor heterogeneity shaped by neutral evolution; however, intratumor heterogeneity in colorectal precancerous lesions has been poorly studied. We perform multiregion whole-exome sequencing on ten early colorectal tumors, which contained adenoma and carcinoma in situ. By comparing with sequencing data from advanced colorectal tumors, we show that the early tumors accumulate a higher proportion of subclonal driver mutations than the advanced tumors, which is highlighted by subclonal mutations in KRAS and APC. We also demonstrate that variant allele frequencies of subclonal mutations tend to be higher in early tumors, suggesting that the subclonal mutations are subject to selective sweep in early tumorigenesis while neutral evolution is dominant in advanced ones. This study establishes that the evolutionary principle underlying intratumor heterogeneity shifts from Darwinian to neutral evolution during colorectal tumor progression.

Photolyase is a DNA repair enzyme that reverses UV-induced photoproducts in DNA in a light-dependent manner. Recently, photolyase homologs were identified in higher eukaryotes. These homologs, termed crypto-chromes, function as blue light photoreceptors or regulators of circadian rhythm. In contrast, most bacteria have only a single photolyase or photolyase-like gene. Unlike other microbes, the chromosome of the cyanobacterium SYNECHOCYSTIS: sp. PCC6803 contains two ORFs (slr0854 and sll1629) with high similarities to photolyases. We have characterized both genes. The slr0854 gene product exhibited specific, light-dependent repair activity for a cyclo-butane pyrimidine dimer (CPD), whereas the sll1629 gene product lacks measurable affinity for DNA in vitro. Disruption of either slr0854 or sll1629 had little or no effect on the growth rate of the cyanobacterium. A mutant lacking the slr0854 gene showed severe UV sensitivity, in contrast to a mutant lacking sll1629. Phylogenetic analysis showed that sll1629 is more closely related to the cryptochromes than photolyases. We conclude that sll1629 is a bacterial cryptochrome. To our knowledge, this is the first description of a bacterial cryptochrome.

Excessive weight gain between 20 and 40 years of age, diabetes mellitus, and lumbago were found to be independent risk factors for ossification of the posterior longitudinal ligament of the spine. Follow-up studies, including the addition of hospital-based control participants and analysis of genetic polymorphisms, will be needed in the future.