Hawk-Seq™ differentiates between various mutations in Salmonella typhimurium TA100 strain caused by exposure to Ames test-positive mutagens.

A precise understanding of differences in genomic mutations according to the mutagenic mechanisms detected in mutagenicity data is required to evaluate the carcinogenicity of environmental mutagens. Recently, we developed a highly accurate genome sequencing method, 'Hawk-Seq™', that enables the detection of mutagen-induced genome-wide mutations. However, its applicability to detect various mutagens and identify differences in mutational profiles is not well understood. Thus, we evaluated DNA samples from Salmonella typhimurium TA100 exposed to 11 mutagens, including alkylating agents, aldehydes, an aromatic nitro compound, epoxides, aromatic amines and polycyclic aromatic hydrocarbons (PAHs). We extensively analysed mutagen-induced mutational profiles and studied their association with the mechanisms of mutagens. Hawk-Seq™ sensitively detected mutations induced by all 11 mutagens, including one that increased the number of revertants by approximately 2-fold in the Ames test. Although the sensitivity for less water-soluble mutagens was relatively low, we increased the sensitivity to obtain high-resolution spectra by modifying the exposure protocol. Moreover, two epoxides indicated similar 6- or 96-dimensional mutational patterns; likewise, three SN1-type alkylating agents indicated similar mutational patterns, suggesting that the mutational patterns are compound category specific. Meanwhile, an SN2 type alkylating agent exhibited unique mutational patterns compared to those of the SN1 type alkylating agents. Although the mutational patterns induced by aldehydes, the aromatic nitro compound, aromatic amines and PAHs did not differ substantially from each other, the maximum total base substitution frequencies (MTSFs) were similar among mutagens in the same structural groups. Furthermore, the MTSF was found to be associated with the carcinogenic potency of some direct-acting mutagens. These results indicate that our method can generate high-resolution mutational profiles to identify characteristic features of each mutagen. The detailed mutational data obtained by Hawk-Seq™ can provide useful information regarding mutagenic mechanisms and help identify its association with the carcinogenicity of mutagens without requiring carcinogenicity data.

Grouping of chemicals based on the potential mechanisms of hepatotoxicity of naphthalene and structurally similar chemicals using in vitro testing for read-across and its validation.

Integrated Approaches to Testing and Assessment provides a framework to improve the reliability of read-across for chemical risk assessment of systemic toxicity without animal testing. However, the availability of only a few case studies hinders the use of this concept for regulatory purposes. Thus, we compared the biological similarity of structurally similar chemicals using in vitro testing to demonstrate the validity of this concept for grouping chemicals and to extract key considerations in read-across. We analyzed the hepatotoxicity of naphthalene and three chemicals structurally similar to naphthalene (2,7-naphthalenediol, 1,5-naphthalenediol, and 1-naphthol) for which 90-day repeated dose toxicity data are available. To elucidate and compare their potential mechanisms, we conducted in vitro microarray analysis using rat primary hepatocytes and validated the results using a biomarker and metabolic activation analysis. We observed that 2,7-naphthalenediol, 1,5-naphthalenediol, and 1-naphthol had similar potential mechanisms, namely, induction of oxidative stress by their metabolic activation. Conversely, naphthalene did not show a similar toxicity effect. The existing in vivo data confirmed our grouping of chemicals based on this potential mechanism. Thus, our findings suggest that in vitro toxicogenomics and related biochemical assays are useful for comparing biological similarities and grouping chemicals based on their toxicodynamics for read-across.

Chemical-induced craniofacial anomalies caused by disruption of neural crest cell development in a zebrafish model.

BACKGROUND: Craniofacial anomalies are among the most frequent birth defects worldwide, and are thought to be caused by gene-environment interactions. Genetically manipulated zebrafish simulate human diseases and provide great advantages for investigating the etiology and pathology of craniofacial anomalies. Although substantial advances have been made in understanding genetic factors causing craniofacial disorders, limited information about the etiology by which environmental factors, such as teratogens, induce craniofacial anomalies is available in zebrafish. RESULTS: Zebrafish embryos displayed craniofacial malformations after teratogen treatments. Further observations revealed characteristic disruption of chondrocyte number, shape and stacking. These findings suggested aberrant development of cranial neural crest (CNC) cells, which was confirmed by gene expression analysis of the CNC. Notably, these observations suggested conserved etiological pathways between zebrafish and mammals including human. Furthermore, several of these chemicals caused malformations of the eyes, otic vesicle, and/or heart, representing a phenocopy of neurocristopathy, and these chemicals altered the expression levels of the responsible genes. CONCLUSIONS: Our results demonstrate that chemical-induced craniofacial malformation is caused by aberrant development of neural crest. This study indicates that zebrafish provide a platform for investigating contributions of environmental factors as causative agents of craniofacial anomalies and neurocristopathy.

Comparison of the potential mechanisms for hepatotoxicity of p-dialkoxy chlorobenzenes in rat primary hepatocytes for read-across.

Read-across based on only structural similarity is considered to have a risk of error in chemical risk assessment. Under these circumstances, considering biological similarity based on adverse outcome pathways using in vitro omics technologies is expected to enhance the accuracy and robustness of conclusions in read-across. However, due to a lack of practical case studies, key considerations and use of these technologies for data gap filling are not well discussed. Here we extracted and compared the potential mechanisms for hepatotoxicity for structural analogs of p-dialkoxy chlorobenzenes including 1,4-dichloro-2,5-dimethoxybenzene (DDMB), 2,5-dichloro-1,4-diethoxybenzene (DDEB), 2-chloro-1,4-dimethoxybenzene (CDMB), and 1-chloro-2,5-diethoxybenzene (CDEB) using in vitro omics technologies for read-across. To reveal the potential mechanisms for hepatotoxicity, we conducted microarray analysis with rat primary hepatocytes. The results showed that three (DDMB, DDEB, CDEB) of the four chemicals affected similar biological pathways such as peroxisome proliferation, oxidative stress, and mitochondrial dysfunction. Furthermore, these biological pathways are consistent with in vivo hepatotoxicity in the source chemical, DDMB. In contrast, CDMB did not affect a specific toxicological pathway. Taken together, these data show the potential mechanisms for hepatotoxicity for three chemicals (DDMB, DDEB, CDEB) and provide novel insights into grouping chemicals using in vitro toxicogenomics for read-across.

Changes in the incidence of cervical lesions owing to the development of rheumatoid arthritis treatment and the impact of cervical lesions on patients' quality of life.

Objectives: To clarify changes in the incidence of cervical lesions in rheumatoid arthritis (RA) patients with advanced treatment and the impact of cervical lesions on the patients' quality of life (QOL).Methods: Incidence of radiographic cervical lesions in 1333 RA patients in 2015 was compared with that in our 1999 survey. The association between cervical lesions and QOL evaluated using three different patient-based questionnaires was also analyzed.Results: The incidence of atlantoaxial subluxation (AAS), vertical subluxation (VS), and subaxial subluxation (SAS) in 2015 decreased by 50%, 75%, and 5%, respectively, compared to the 1999 survey. Although QOL, evaluated using the Japanese Orthopedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ; specific to myelopathy), deteriorated as the cervical lesion progressed, there was no association between cervical lesion progression and QOL evaluated using the Short Form-8™ (SF-8™; comprehensive health-related QOL). Cervical lesion progression was also associated with QOL deterioration evaluated using the Health Assessment Questionnaire Disability Index (HAQ-DI; specific to RA), but age and disease duration had stronger influences.Conclusion: The incidence of cervical lesions decreased in 2015 compared to 1999. Cervical lesion progression may be associated with QOL deterioration due to myelopathy. Age and disease duration have more impact on disease-specific QOL.

A decision tree-based integrated testing strategy for tailor-made carcinogenicity evaluation of test substances using genotoxicity test results and chemical spaces.

Genotoxicity evaluation has been widely used to estimate the carcinogenicity of test substances during safety evaluation. However, the latest strategies using genotoxicity tests give more weight to sensitivity; therefore, their accuracy has been very low. For precise carcinogenicity evaluation, we attempted to establish an integrated testing strategy for the tailor-made carcinogenicity evaluation of test materials, considering the relationships among genotoxicity test results (Ames, in vitro mammalian genotoxicity and in vivo micronucleus), carcinogenicity test results and chemical properties (molecular weight, logKow and 179 organic functional groups). By analyzing the toxicological information and chemical properties of 230 chemicals, including 184 carcinogens in the Carcinogenicity Genotoxicity eXperience database, a decision tree for carcinogenicity evaluation was optimised statistically. A decision forest model was generated using a machine-learning method-random forest-which comprises thousands of decision trees. As a result, balanced accuracies in cross-validation of the optimised decision tree and decision forest model, considering chemical space (71.5% and 75.5%, respectively), were higher than balanced accuracy of an example regulatory decision tree (54.1%). Moreover, the statistical optimisation of tree-based models revealed significant organic functional groups that would cause false prediction in standard genotoxicity tests and non-genotoxic carcinogenicity (e.g., organic amide and thioamide, saturated heterocyclic fragment and aryl halide). In vitro genotoxicity tests were the most important parameters in all models, even when in silico parameters were integrated. Although external validation is required, the findings of the integrated testing strategies established herein will contribute to precise carcinogenicity evaluation and to determine new mechanistic hypotheses of carcinogenicity.

Genome-wide somatic mutation analysis via Hawk-Seq™ reveals mutation profiles associated with chemical mutagens.

It is difficult to identify mutagen-induced genome-wide somatic mutations using next generation sequencing; hence, mutagenic features of each mutagen and their roles in cancer development require further elucidation. We described Hawk-Seq™, a highly accurate genome sequencing method and the optimal conditions, for using it to construct libraries that would enable the accurate (c.a. 1 error/107-108 bp) and efficient survey of genome-wide mutations. Genomic mutations in gpt delta mice or Salmonella typhimurium TA100 exposed to methylnitrosourea (MNU), ethylnitrosourea (ENU), diethylnitrosamine (DEN), benzo[a]pyrene (BP), and aristolochic acid (AA) were profiled using Hawk-Seq™ to analyse positions, substitution patterns, or frequencies. The resultant vast mutation data provided high-resolution mutational signatures, including for minor mutational fractions (e.g. G:C>A:T by AA), which enabled the clarification of the mutagenic features of all mutagens. The 96-type mutational signatures of MNU, AA, and BP indicate their partial similarity to signature 11, 22, and 4 or 29, respectively. Meanwhile, signatures attributable to ENU and DEN were highly similar to each other, but not to signature 11, suggesting that the mechanisms of these agents differed from those of typical alkylating agents. Thus, Hawk-Seq™ can clarify genome-wide chemical mutagenicity profiles at extraordinary resolutions, thereby providing insight into mutagen mechanisms and their roles in cancer development.

Prevalence of and factors associated with dysfunctional low back pain in patients with rheumatoid arthritis.

PURPOSE: To investigate the prevalence of and factors associated with dysfunctional low back pain (LBP) in patients with rheumatoid arthritis (RA). METHODS: This cross-sectional study included 1276 RA outpatients from two hospitals. The Roland-Morris Disability Questionnaire was used to address the functional-dysfunctional state criterion. Clinical variables, such as medical status, disease activity, bone mineral density, and spinopelvic alignment parameters, were compared between patients with and without dysfunctional LBP. RESULTS: Mean age and disease duration were 64.6 and 13.4 years, respectively; the prevalence of dysfunctional LBP was 32.8%. On univariate analysis, significant differences existed in many variables, except sex, body weight, C-reactive protein (CRP) level, and prevalence of biological agent users, between patients with and without dysfunctional LBP. Multivariate logistic regression analysis revealed body mass index (BMI; odds ratio [OR], 1.116; P < 0.001), onset age of RA (OR, 1.020; P = 0.020), disease duration of RA (OR, 1.043; P < 0.001), methotrexate (MTX) use (OR, 0.609; P = 0.007), vertebral fractures (OR, 2.189; P = 0.001), vertebral endplate and/or facet erosion (OR, 1.411; P = 0.043), disease activity score (DAS) in 28 joints-CRP (DAS-28CRP) (OR, 1.587; P = 0.001), pelvic tilt (PT; OR, 1.023; P = 0.019), and sagittal vertical axis (SVA; OR, 1.007; P = 0.043) as associated factors. CONCLUSION: The factors associated with dysfunctional LBP in patients with RA were more vertebral fractures, higher DAS-28CRP, vertebral endplate and/or facet erosion, higher BMI, longer disease duration, greater PT, older onset age, greater SVA, and less MTX use. Strictly controlling patients' body weight and disease activity with MTX and avoiding spinopelvic malalignment through vertebral fracture prevention are important. These slides can be retrieved under Electronic Supplementary Material.

Effects of dietary alpha-linolenic acid-enriched diacylglycerol oil on embryo/fetal development in rats.

Recent studies suggest that diets supplemented with alpha-linolenic acid (ALA)-enriched diacylglycerol (DAG) oil provide potential health benefits in preventing or managing obesity. However, available safety information about reproductive and developmental toxicities of ALA-DAG oil is limited. This study was conducted to clarify the effect, if any, of ALA-DAG oil on embryo-fetal development, following maternal exposure during the critical period of major organogenesis. ALA-DAG oil was administered via gavage to pre-mated female Sprague Dawley rats from gestation day 6 through 19, at dose levels of 0, 1.25, 2.5, and 5.0 mL/kg/day (equivalent to 0, 1149, 2325, and 4715 mg/kg/day, respectively), with total volume adjusted to 5 mL/kg/day with rapeseed oil. All females survived to the scheduled necropsy. There were no treatment-related changes in clinical or internal findings, maternal body weights, feed consumption, intrauterine growth, survival, and number of implantations. No ALA-DAG oil-related fetal malformations or developmental variations were noted. A maternal maximum tolerated dose for ALA-DAG oil could not be achieved in this study. Based on these results, a dose level of 5.0 mL/kg (4715 mg/kg/day), the highest dose tested, was considered as the no-observed-adverse-effect level (NOAEL) for both maternal and developmental toxicity.

A 90-day repeated-dose toxicity study of dietary alpha linolenic acid-enriched diacylglycerol oil in rats.

Diets supplemented with alpha-linolenic acid (ALA)-enriched diacylglycerol (DAG) oil-which mainly consists of oleic and linolenic, linoleic acids-have potential health benefits in terms of preventing or managing obesity. Although safety of DAG oil has been extensively investigated, toxicity of ALA-DAG oil has not been well understood. Hence, the present study was conducted to clarify the potential adverse effects, if any, of ALA-DAG oil in rats (10/sex/group) fed diets containing 1.375%, 2.75%, or 5.5% ALA-DAG oil for 90 days. Compared to control rats fed rapeseed oil or ALA-triacylglycerol oil (flaxseed oil), rats receiving ALA-DAG oil did not reveal any toxicologically significant treatment-related changes as evaluated by clinical signs, functional observational battery, body weight, food consumption, ophthalmology, urinalysis, hematology, clinical chemistry, organ weight, necropsy and histopathology. The no observed adverse effect levels for dietary exposure to ALA-DAG oil for male and female rats were 2916 and 3326 mg/kg body weight/day, respectively, the highest dose tested. The findings from this study suggest that consumption of ALA-DAG oil is unlikely to cause adverse effects.

Discriminating between adaptive and carcinogenic liver hypertrophy in rat studies using logistic ridge regression analysis of toxicogenomic data: The mode of action and predictive models.

Chemical exposure often results in liver hypertrophy in animal tests, characterized by increased liver weight, hepatocellular hypertrophy, and/or cell proliferation. While most of these changes are considered adaptive responses, there is concern that they may be associated with carcinogenesis. In this study, we have employed a toxicogenomic approach using a logistic ridge regression model to identify genes responsible for liver hypertrophy and hypertrophic hepatocarcinogenesis and to develop a predictive model for assessing hypertrophy-inducing compounds. Logistic regression models have previously been used in the quantification of epidemiological risk factors. DNA microarray data from the Toxicogenomics Project-Genomics Assisted Toxicity Evaluation System were used to identify hypertrophy-related genes that are expressed differently in hypertrophy induced by carcinogens and non-carcinogens. Data were collected for 134 chemicals (72 non-hypertrophy-inducing chemicals, 27 hypertrophy-inducing non-carcinogenic chemicals, and 15 hypertrophy-inducing carcinogenic compounds). After applying logistic ridge regression analysis, 35 genes for liver hypertrophy (e.g., Acot1 and Abcc3) and 13 genes for hypertrophic hepatocarcinogenesis (e.g., Asns and Gpx2) were selected. The predictive models built using these genes were 94.8% and 82.7% accurate, respectively. Pathway analysis of the genes indicates that, aside from a xenobiotic metabolism-related pathway as an adaptive response for liver hypertrophy, amino acid biosynthesis and oxidative responses appear to be involved in hypertrophic hepatocarcinogenesis. Early detection and toxicogenomic characterization of liver hypertrophy using our models may be useful for predicting carcinogenesis. In addition, the identified genes provide novel insight into discrimination between adverse hypertrophy associated with carcinogenesis and adaptive hypertrophy in risk assessment.

Genome resequencing analysis of Salmonella typhimurium LT-2 strains TA98 and TA100 for the establishment of a next-generation sequencing-based mutagenicity assay.

Next-generation sequencing (NGS) is a potentially useful technology to achieve a more precise evaluation of chemical mutagenicity. To establish NGS-based mutagenicity assays, which enable the direct detection of chemically induced mutations in a whole genome manner, the selection of appropriate biological resources and their precise genome sequences are essential. Here, we performed genome re-sequencing analyses of Salmonella typhimurium LT-2 strains TA98 and TA100, which have been frequently used in mutagenicity assays. We identified several strain-specific mutations including those that were relevant to their known phenotypes (his, ΔuvrB and rfa). The details of rfa mutations were first clarified in this study, which was a frameshift variant in rfaF and a missense variant in rfaC in TA98 and TA100, respectively. The uvrB deletion in TA98 was larger than that in TA100, which suggested differences in defects of lipopolysaccharide synthesis between these strains. The re-sequenced genome data of TA98 and TA100 will help us establish NGS-based bacterial mutagenicity assays and understand the biological events seen in them. Copyright © 2017 John Wiley & Sons, Ltd.

Multidrug resistance-associated protein 2 (MRP2) is an efflux transporter of EGCG and its metabolites in the human small intestine.

Green tea polyphenols have various beneficial effects on human health, such as antiobesity and anti-carcinogenesis. (-)-Epigallocatechin-gallate (EGCG) is one of the major potent green tea catechins; however, detailed mechanisms of EGCG transport and metabolism in the human small intestine remain unknown due to lack of a suitable model. We investigated metabolite profiles of EGCG in the fresh human duodenal biopsy, cryopreserved human duodenal mucosal enterocytes and Caco-2 cells, and found that EGCG was readily metabolized into methylated and sulphate conjugates, which are major metabolites in these models. Next, we examined possible efflux transporters of EGCG and its metabolites using specific inhibitors of MRP2, P-gp and BCRP in Caco-2 cell monolayers. MRP2 was thereby identified as an efflux transporter, and further analysis using MRP2-knockout Caco-2 cells and vesicular transport assays confirmed that MRP2 is a selective efflux transporter of EGCG and its metabolites. Assuming that functional inhibition of MRP2 would result in efficient uptake of EGCG, we screened for MRP2 functional blockade and identified quercetin, which led to increased intracellular accumulation and basal transport of EGCG in Caco-2 cells. This result suggested that co-administration of quercetin and EGCG would enable efficient transport of EGCG in the human intestine. Therefore, we performed co-oral administration of quercetin and EGCG in human subjects to examine whether this occurred in humans. These studies demonstrated that MRP2 is a selective transporter of EGCG and conjugates and Caco-2 is a model to examine transport mechanisms and metabolites of polyphenols in the human small intestine.

Effects of internal hydrophilic groups of a newly developed sustainable anionic surfactant on biodegradability and ecotoxicity.

Recently, a new sustainable anionic surfactant called bio-based internal olefin sulfonate (Bio IOS) has been developed. This surfactant enables excellent water solubility and high surface activity. It has a unique structure of long hydrophobic alkyl chains (C16 to C18) with two types of hydrophilic groups in its midsection, which distinguish it from other conventional anionic surfactants. However, the effects of the specific structural features of the surfactant on its environmental properties and the consequent effects on the environment remain unclear. In this study, we investigated the environmental fate and ecotoxicity of Bio IOS and the effects of the types and positions of hydrophilic groups on biodegradability and ecotoxicity. Biodegradation studies demonstrated that Bio IOS was readily biodegradable with >99.5% removal in wastewater treatment activated sludge (test concentration: 1 mg/L) and a fast half-life of 5.8 h in river water (test concentration: 10 µg/L); the excellent biodegradability was likely due to the high water solubility attributed to the internal hydrophilic groups. Meanwhile, moderately toxic effects were observed, whereby the 50% lethal and effect concentrations of the three freshwater species were above 1 mg/L. Ecotoxicity studies with different types and positions of hydrophilic groups revealed that hydroxyalkane sulfonate was less toxic and that toxicity was reduced in the presence of more internally located hydrophilic groups. These findings suggest that the hydroxyl group and the internal positions of hydrophilic groups that constitute the molecular configuration resembling two separate shorter alkyl chains may reduce the adverse effects on organisms despite the long alkyl chains.

4″-Sulfation Is the Major Metabolic Pathway of Epigallocatechin-3-gallate in Humans: Characterization of Metabolites, Enzymatic Analysis, and Pharmacokinetic Profiling.

Epigallocatechin-3-gallate (EGCG), a major green tea polyphenol, has beneficial effects on human health. This study aimed to elucidate the detailed EGCG sulfation process to better understand its phase II metabolism, a process required to maximize its health benefits. Results show that kinetic activity of sulfation in the human liver and intestinal cytosol is 2-fold and 60- to 300-fold higher than that of methylation and glucuronidation, respectively, suggesting sulfation as the key metabolic pathway. Moreover, SULT1A1 and SULT1A3 are responsible for sulfation in the liver and intestine, respectively. Additionally, our human ingestion study revealed that the concentration of EGCG-4″-sulfate in human plasma (Cmax: 177.9 nmol·L-1, AUC: 715.2 nmol·h·L-1) is equivalent to free EGCG (Cmax: 233.5 nmol·L-1, AUC: 664.1 nmol·h·L-1), suggesting that EGCG-4″-sulfate is the key metabolite. These findings indicate that sulfation is a crucial factor for improving EGCG bioavailability, while also advancing the understanding of the bioactivity and toxicity of EGCG.

Comparative environmental RNA and DNA metabarcoding analysis of river algae and arthropods for ecological surveys and water quality assessment.

Environmental DNA (eDNA) metabarcoding is widely used for species analysis, while the use of environmental RNA (eRNA) metabarcoding is more limited. We conducted comparative eDNA/eRNA metabarcoding of the algae and arthropods (aquatic insects) in water samples from Naka River, Japan, to evaluate their potential for biological monitoring and water quality assessment. Both methods detected various algae and arthropod species; however, their compositions were remarkably different from those in traditional field surveys (TFSs), indicating low sensitivity. For algae, the species composition derived from eDNA and eRNA metabarcoding was equivalent. While TFSs focus on attached algae, metabarcoding analysis theoretically detects both planktonic and attached algae. A recently expanded genomic database for aquatic insects significantly contributed to the sensitivity and positive predictivity for arthropods. While the sensitivity of eRNA was lower than that of eDNA, the positive predictivity of eRNA was higher. The eRNA of terrestrial arthropods indicated extremely high or low read numbers when compared with eDNA, suggesting that eRNA could be an effective indicator of false positives. Arthropod and algae eDNA/eRNA metabarcoding analysis enabled water quality estimates from TFSs. The eRNA of algae and arthropods could thus be used to evaluate biodiversity and water quality and provide insights from ecological surveys.

Low back pain in childhood and adolescence: assessment of sports activities.

A cross-sectional study that targeted a total of 43,630 pupils in Niigata City, Japan was performed. The objective of the study was to evaluate the association between sports activities and low back pain (LBP) in childhood and adolescence in Japan. Regarding risk factors of LBP, a large number of studies have been conducted that have examined gender differences, height and weight, body mass index, sports time, differences in lifestyle, family history, and mental factors; however, no definitive conclusion has yet been made. A questionnaire survey was conducted using 43,630 pupils, including all elementary school pupils from the fourth to sixth grade (21,893 pupils) and all junior high pupils from the first to third year (21,737 pupils) in Niigata City (population of 785,067). 26,766 pupils who were determined to have valid responses (valid response rate 61.3%) were analyzed. Among the 26,766 pupils with valid responses, 2,591 (9.7%) had LBP at the time of the survey, and 8,588 (32.1%) had a history of LBP. The pupils were divided between those who did not participate in sports activities except the physical education in school (No sports group: 5,486, 20.5%) and those who participated in sports activities (Sports group: 21,280, 79.5%), and the difference in lifetime prevalence between No sports group and Sports group was examined. The odds ratio for LBP according to sports activity was calculated by multiple logistic regression analysis adjusted for gender, age, and body mass index. In addition, the severity of LBP was divided into three levels (Level 1: no limitation in any activity, Level 2: necessary to refrain from participating in sports and physical activities, and Level 3: necessary to be absent from school), and Levels 2 and 3 were defined as severe LBP; the severity was compared between No sports group and Sports group and in each sport's items. Moreover, in Sports group, the amount of time spent participating in sports activities were divided into three groups (Group 1: less than 6 h per week, Group 2: 6-12 h per week, and Group 3: 12.1 h per week or more), and the dose-response between the amount of time spent participating in sports activities and the occurrence of LBP were compared. In No sports group, 21.3% experienced a history of LBP; in Sports group, 34.9% experienced LBP (P < 0.001). In comparison to No sports group, the odds ratio was significantly higher for Sports group (1.57), and also significantly higher for most of the sports items. The severity of LBP was significantly higher in Sports group (20.1 vs. 3.2%, P < 0.001). The amount of time spent participating in sports activities averaged 9.8 h per week, and a history of LBP significantly increased in the group which spent a longer time participating in sports activities (odds ratio 1.43 in Group 3). These findings suggest that sports activity is possible risk factors for the occurrence of LBP, and it might increase the risk for LBP in childhood and adolescence.

Back pain in adolescents with idiopathic scoliosis: epidemiological study for 43,630 pupils in Niigata City, Japan.

There have been a few studies regarding detail of back pain in adolescents with idiopathic scoliosis (IS) as prevalence, location, and severity. The condition of back pain in adolescents with IS was clarified based on a cross-sectional study using a questionnaire survey, targeting a total of 43,630 pupils, including all elementary school pupils from the fourth to sixth grade (21,893 pupils) and all junior high pupils from the first to third year (21,737 pupils) in Niigata City (population of 785,067), Japan. 32,134 pupils were determined to have valid responses (valid response rate: 73.7%). In Niigata City, pupils from the fourth grade of elementary school to the third year of junior high school are screened for scoliosis every year. This screening system involves a three-step survey, and the third step of the survey is an imaging and medical examination at the Niigata University Hospital. In this study, the pupils who answered in the questionnaire that they had been advised to visit Niigata University Hospital after the school screening were defined as Scoliosis group (51 pupils; 0.159%) and the others were defined as No scoliosis group (32,083 pupils). The point and lifetime prevalence of back pain, the duration, the recurrence, the severity and the location of back pain were compared between these groups. The severity of back pain was divided into three levels (level 1 no limitation in any activity; level 2 necessary to refrain from participating in sports and physical activities, and level 3 necessary to be absent from school). The point prevalence was 11.4% in No scoliosis group, and 27.5% in Scoliosis group. The lifetime prevalence was 32.9% in No scoliosis group, and 58.8% in Scoliosis group. According to the gender- and school-grade-adjusted odds ratios (OR), Scoliosis group showed a more than twofold elevated odds of back pain compared to No scoliosis group irrespective of the point or lifetime prevalence of back pain (OR, 2.29; P = 0.009 and OR, 2.10; P = 0.012, respectively). Scoliosis group experienced significantly more severe pain, and of a significantly longer duration with more frequent recurrences in comparison to No scoliosis group. Scoliosis group showed significantly more back pain in the upper and middle right back in comparison to No scoliosis group. These findings suggest that there is a relationship between pain around the right scapula in Scoliosis group and the right rib hump that is common in IS.

Clinical outcomes of posterior lumbar interbody fusion for lumbar foraminal stenosis: preoperative diagnosis and surgical strategy.

STUDY DESIGN: A retrospective case study of the use of posterior lumbar interbody fusion (PLIF) to treat lumbar foraminal stenosis (LFS). OBJECTIVES: To characterize the features of clinical symptoms, radiographic evaluation, and surgical outcomes of PLIF in LFS. SUMMARY OF BACKGROUND DATA: There is no gold standard for the surgical treatment of foraminal stenosis, which occurs in 8% to 10% of surgical cases of lumbar degenerative disease. METHODS: Data from 31 patients (33 segments) who underwent PLIF from 2001 to 2005 at our institution were analyzed. Exclusion criteria included the patients having both LFS and central canal stenosis, plus extraforaminal or intraforaminal disc herniation. There were 22 males and 9 females, with an average age of 61 (31~78 y). The affected levels were as follows: L3/4 in 1 patient, L4/5 in 4, and L5/S1 in 28. All patients underwent PLIF with the combination of segmental pedicle screws, interbody cages, and autogenous local bone graft. RESULTS: The frequencies of Kemp sign (+), intermittent claudication, leg pain in a sitting position, and leg pain at night, were high. Radiographic evaluation showed severe disc degeneration such as loss of disc height, massive osteophyte formation, and transverse offset angles of the nerve root at the corresponding level. Magnetic resonance imaging and 3D-reconstraction computed tomography clearly showed intraforaminal stenosis in sagittal, axial, and coronal planes. The PLIF procedure provided complete root decompression, restoration of disc height, and preservation of lumbar lordosis at final follow-up. The Japanese Orthopedic Association score improved from 17.1 points preoperatively to 24.9 points at final follow-up, and the overall fusion rate was 100%. CONCLUSION: Lumbar foraminal stenosis could be reliably diagnosed by distinctive clinical symptoms, and various radiographic examinations such as plain x-ray, Magnetic resonance imaging, and 3D-reconstraction computed tomography. The PLIF procedure, in combination with segmental pedicle screws, interbody cages, and autogenous local bone graft provides excellent clinical outcomes, and is a rational and useful surgical option for lumbar foraminal stenosis.

In Silico Model for Chemical-Induced Chromosomal Damages Elucidates Mode of Action and Irrelevant Positives.

In silico tools to predict genotoxicity have become important for high-throughput screening of chemical substances. However, current in silico tools to evaluate chromosomal damage do not discriminate in vitro-specific positives that can be followed by in vivo tests. Herein, we establish an in silico model for chromosomal damages with the following approaches: (1) re-categorizing a previous data set into three groups (positives, negatives, and misleading positives) according to current reports that use weight-of-evidence approaches and expert judgments; (2) utilizing a generalized linear model (Elastic Net) that uses partial structures of chemicals (organic functional groups) as explanatory variables of the statistical model; and (3) interpreting mode of action in terms of chemical structures identified. The accuracy of our model was 85.6%, 80.3%, and 87.9% for positive, negative, and misleading positive predictions, respectively. Selected organic functional groups in the models for positive prediction were reported to induce genotoxicity via various modes of actions (e.g., DNA adduct formation), whereas those for misleading positives were not clearly related to genotoxicity (e.g., low pH, cytotoxicity induction). Therefore, the present model may contribute to high-throughput screening in material design or drug discovery to verify the relevance of estimated positives considering their mechanisms of action.