Effects of sudden unexpected mechanical perturbation training aimed at the primary prevention of inversion ankle sprain on reactiveness of ankle movement and cortical activity in normal young adults.

[Purpose] To determine the effects of sudden unexpected mechanical perturbation training aimed at the primary prevention of inversion ankle sprain on the reactiveness of ankle eversion movement and cortical activity. [Participants and Methods] Sixty healthy participants were randomly allocated equally into 1) the sudden unexpected mechanical perturbation training group, 2) self-paced training group, or 3) control group. The first two groups performed each course of training 3 days per week for 4 weeks. During pre-training and post-training, the latency to peak amplitude on the surface electromyography of the peroneus longus and the time to reposition the plate back to its initial position under the right foot after sudden unexpected mechanical perturbation were measured. Functional near-infrared spectroscopy was used to measure the changes in the concentration of oxygenated hemoglobin. [Results] The latency to peak amplitude was significantly shorter in group 1 than in group 2; time to reposition the plate was the shortest among the 3 groups during post-training. The changes in the concentration of oxygenated hemoglobin were significantly increased in the supplementary motor and pre-motor areas during post-training than during pre-training in group 1. [Conclusion] Sudden unexpected mechanical perturbation training may facilitate the primary prevention of inversion ankle sprain via the positive effects on the reactiveness of ankle eversion movement and cortical activity.

Mutagenicity and clastogenicity of extracts of Helicobacter pylori detected by the Ames test and in the micronucleus test using human lymphoblastoid cells.

Epidemiological studies have demonstrated a close association between infection with Helicobacter pylori (H.pylori) and the development of gastric carcinoma. Chronic H.pylori infection increases the frequency of mutation in gastric epithelial cells. However, the mechanism by which infection of H.pylori leads to mutation in gastric epithelial cells is unclear. We suspected that components in H.pylori may be related to the mutagenic response associated with DNA alkylation, and could be detected with the Ames test using a more sensitive strain for alkylating agents. Our investigation revealed that an extract of H.pylori was mutagenic in the Ames test with Salmonella typhimurium YG7108, which is deficient in the DNA repair of O(6)-methylguanine. The extract of H.pylori may contain methylating or alkylating agents, which might induce O (6)-alkylguanine in DNA. Mutagenicity of the alkylating agents N-methyl-N-nitrosourea (MNU) and N-methyl-N'-nitro-N-nitrosoguanidine in the Ames test with S.typhimurium TA1535 was enhanced significantly in the presence of the extract of H.pylori. The tested extracts of H.pylori resulted in a significant induction of micronuclei in human-derived lymphoblastoid cells. Heat instability and dialysis resistance of the extracts of H.pylori suggest that the mutagenic component in the extracts of H.pylori is a heat-unstable large molecule or a heat-labile small molecule strongly attached or adsorbed to a large molecule. Proteins in the extracts of H.pylori were subsequently fractionated using ammonium sulphate precipitation. However, all fractions expressed enhancing effects toward MNU mutagenicity. These results suggest the mutagenic component is a small molecule that is absorbed into proteins in the extract of H.pylori, which resist dialysis. Continuous and chronic exposure of gastric epithelial cells to the alkylative mutagenic component from H.pylori chronically infected in the stomach might be a causal factor in the gastric carcinogenesis associated with H.pylori.

4G/5G variant of plasminogen activator inhibitor-1 gene and severe pregnancy-induced hypertension: subgroup analyses of variants of angiotensinogen and endothelial nitric oxide synthase.

BACKGROUND: Pregnancy-induced hypertension (PIH) is a common cause of perinatal mortality. It is believed to result from the interaction of several factors, including those related to the blood coagulation system. We performed genotyping and subgroup analyses to determine if the 4G/5G genotypes of the plasminogen activator inhibitor-1 gene (PAI-1) play a role in the pathogenesis of PIH, and to evaluate possible interactions of the PAI-1 polymorphisms with those of the angiotensinogen gene (AGT) and the endothelial nitric oxide synthase gene (NOS3). METHODS: An association study of PAI-1 polymorphism, and subgroup analyses of common variants of AGT and NOS3, among 128 patients with PIH and 376 healthy pregnant controls. RESULTS: No significant differences were found between the cases and controls in the frequencies of allele 4G or the 4G/4G genotype. In subgroup analyses, after adjustment for multiple comparison, a significant association with the AGT TT genotype was found among women with the PAI-1 4G/4G genotype, and an association with the NOS3 GA+AA genotype was found among women with the 5G/5G or 4G/5G genotypes. CONCLUSIONS: Our findings suggest that there are at least 2 pathways in the pathogenesis of severe PIH. However, with respect to early prediction and prevention of severe PIH, although the PAI-1 4G/4G genotype alone was not a risk factor for severe PIH, the fact that PAI-1 genotypes are associated with varying risks for severe PIH suggests that PAI-1 genotyping of pregnant women, in combination with other tests, may be useful in the development of individualized measures that may prevent severe PIH.

[Identification of propionibacterium acnes in a case with stage III pulmonary sarcoidosis involving hepatosplenic disease].

A 35-year-old woman was admitted to our hospital because of an abnormal chest radiograph. Chest X-ray on admission showed multiple small nodular shadows in both lung fields but no bilateral hilar lymphadenopathy (BHL). Moreover, abdominal CT showed some nodules in the liver and spleen, and serum ACE was slightly increased to 23.3U/L (normal range: 8.3-21.4U/L). Transbronchial lung biopsy and liver biopsy resulted in a diagnosis of stage III pulmonary sarcoidosis with hepatosplenic disease. Histopathological findings demonstrated non-caseating epithelioid cell granulomas with giant cells in both specimens. Interestingly, propionibacterium acnes (P. acnes), the possible pathogen of sarcoidosis, was detected in giant cells in the lung and epitheliod cell granuloma of liver tissue. This case was of interest considering P. acnes might have been the causative pathogen.

[A case of pulmonary intravascular lymphoma treated with CHOP chemotherapy plus rituximab].

We report a case of pulmonary intravascular lymphoma of large B cell type in a 72-year-old woman. She had a one-month history of fever and dry cough before admission. Chest X-ray revealed ground glass shadow in both lung fields, and the high-resolution CT disclosed centrilobular distribution of ground glass opacities. Transbronchial lung biopsy demonstrated large lymphoid cells in the capillaries of alveolar septa. The tumor cells showed strong immunohistochemical reactivity to CD 20. After combined treatment with CHOP and rituximab, clinical symptoms, laboratory and radiological findings were improved. As with diffuse large B cell lymphoma, CHOP chemotherapy plus rituximab may prove useful as a standard regimen for pulmonary intravascular lymphoma.

[From a view of the wheelchair users--a training report of the students on barrier-free environment in Sapporo].

This short report describes what we learned from our training session on the use of the wheelchair in the various parts of Sapporo City. The session was conducted in July 2000 as one of the public health field training programs for fourth-year medical students of Hokkaido University School of Medicine. We, as a set of 5 people with the wheelchair, actually toured the street, subways, big department stores, banks, and other public facilities and buildings to assess their social and physical environment in a context of barrier-free society, so that some suggestions may be given to the City for the development of an appropriate welfare system. We also evaluated people's attitudes to the wheelchair users. We learned that 1) it is not easy for the wheelchair users to move around; it's much more difficult than we thought; 2) there are a lot of barriers and obstacles in a social environment for the wheelchair users; 3) many people have not noticed these barriers. This training was very instrumental in terms of understanding the barrier-free environment from the view of wheelchair users. Comprehensive city planning is necessary to accommodate the various individuals and senior citizens with different handicaps. Furthermore, our own view of a barrier-free society must be changed.

Pharmaceutical company perspectives on current safety risk communications in Japan.

In 1987, a group infection of hepatitis in patients receiving a contaminated fibrinogen product was first reported to the Japanese regulatory agency. Eventually, this serious drug incident involved more than 10,000 cases of infection. In response, the Government of Japan established a responding inspection committee in 2008 to make recommendations for the restructuring of drug regulatory administration. The final report was issued in 2010. One agenda item of this restructuring was the improvement of drug-related safety risk communications. Our research group on drug safety risk communications, which is funded by the Government of Japan, surveyed pharmaceutical companies regarding their perspective on current risk communications. The survey was conducted using an anonymous questionnaire developed for this study which included the three operational domains of targets, contents, and measures of drug risk communication. Fifty-two of the 74 member companies of the Post-marketing Surveillance Subcommittee of the Japan Pharmaceutical Manufacturer's Association participated, and this response rate of more than 70% was considered sufficient to ensure the external validity of the survey results. Results showed that the most highly prioritized aspect of risk messaging was the strength of evidence, and that outcome evaluation of risk communication gained recognition. Further, while physicians and pharmacists were the most prioritized communication targets, pharmacovigilance departments devoted the most resources to regulators, at more than 30%. The Internet was recognized as a useful public source of risk information, whereas Drug Guides for Patients delivered on the web were considered under-recognized. Further discussion of these results with the aim of enhancing the restructuring of the Japanese drug regulatory administration system are warranted.

Anti-beta2 glycoprotein-I antibody increases the risk of pregnancy-induced hypertension: a case-controlled study.

The aim of this study was to evaluate whether anti-beta2 glycoprotein-I antibody (anti-beta2GPI) of the IgG or IgM classes is associated with the development of pregnancy-induced hypertension (PIH) or preeclampsia in the Japanese population. In a case-controlled cohort study, peripheral blood was obtained at 8-14 weeks of gestation from a consecutive series of 1155 women. The case group comprised 36 patients who later developed PIH during the pregnancy. Of the 36 PIH patients, 13 had severe PIH, 18 had preeclampsia and 11 had severe preeclampsia. One hundred and eleven age- and parity-matched women whose pregnancies ended in normal delivery without obstetric complications were selected as controls. We found that a titer of anti-beta2GPI IgG>or=1.0 U/ml was a risk factor for severe PIH (P=0.023, OR 5.7 95%CI 1.4-22.8). In addition, titers of anti-beta2GPI IgM>or=1.2 U/ml was found to be a risk factor for PIH (P=0.001, OR 8.8 95%CI 1.6-47.5). In women positive for anti-beta2GPI but negative for lupus anticoagulant, anti-cardiolipin, phosphatidylserine-dependent anti-prothrombin, or kininogen-dependent anti-phosphatidylethanolamine antibodies, the presence of anti-beta2GPI was not a significant risk factor for development of PIH or preeclampsia. In conclusion, the presence of anti-beta2GPI antibody represents a risk factor for developing PIH and severe PIH. This finding supports the utility of anti-beta2GPI determination as one of the laboratory criteria for anti-phospholipid syndrome classification. The usefulness of anti-beta2GPI measurement among women without other anti-phospholipid antibodies requires further study.

Antiphospholipid antibodies increase the risk of pregnancy-induced hypertension and adverse pregnancy outcomes.

Antiphospholipid antibody (aPL) is associated with thromboembolism. There is scant evidence of a relationship between the aPL profile and serious adverse pregnancy outcome. The aim of this study was to assess whether aPL measurements during early pregnancy were useful in predicting a serious adverse pregnancy outcome. In this prospective study, we measured aPLs, including lupus anticoagulant (LA), IgG, IgM, IgA anticardiolipin antibody (aCL), IgG, IgM phosphatidylserine-dependent antiprothrombin antibody, and IgG kininogen-dependent antiphosphatidylethanolamine antibody (aPE) during the first trimester in a consecutive series of 1155 women. The 99 th percentile cut-off values in each aPL were determined using samples from 105 women who did not exhibit any pregnancy morbidity. We assessed the predictive risk of a serious adverse pregnancy outcome adjusted for confounding factors. We found that IgG aCL was associated with developing pregnancy-induced hypertension (PIH) (odds ratio 11.4, 95% CI 2.7-48); IgG aPE with PIH (8.3, 2.4-29), severe PIH (20.4, 4.5-91), and premature delivery (PD) (12.7, 3.1-50); and LA with PD (11.0, 2.8-44) and low birth weight (8.0, 2.1-31). The combinations of IgG aPE plus IgG aCL (17.5, 4.7-66.7) or IgG aPE plus LA (22.2, 5.4-909) measurements predicted severe PIH with 30.8% sensitivity and 99.2% specificity. We conclude that aPL measurements during early pregnancy may be useful in predicting adverse pregnancy outcome.

FokI variant of vitamin D receptor gene and factors related to atherosclerosis associated with ossification of the posterior longitudinal ligament of the spine: a multi-hospital case-control study.

STUDY DESIGN: A sex- and age-matched case-control study with genotyping of the FokI variant of the vitamin D receptor gene (VDR) was carried out. OBJECTIVES: To facilitate the early prediction, prevention, and treatment of ossification of the posterior longitudinal ligament (OPLL) of the spine, we analyzed the FokI variant of VDR and past body mass indexes, histories of past illness, family history, and body pliability along with lifestyle factors. SUMMARY OF BACKGROUND DATA: Many possible genetic and environmental risk factors for OPLL have been suggested, including male sex, high body mass index, diabetes mellitus, trauma, hormonal imbalance, and dietary and sleeping habits and genetic variants. METHODS: Both a self-administered questionnaire and whole blood samples were obtained from 63 patients with OPLL and 126 sex-, age-, and hospital-matched controls free of backbone diseases were randomly selected from hospital patients. VDR genotyping was carried out using PCR-RFLP methods. After univariate analysis, multivariate and subgroup analyses according to the VDR genotype was applied to clarify the confounding relationship between VDR genotype and other possible risk factors. RESULTS: A multivariate analysis revealed that the VDR FF genotype, family history of myocardial infarction, high body mass index at age 40, long working hours, and working with night shift to be independent potent risk factors for OPLL. CONCLUSION: The risk of developing OPLL may possibly be reduced gradually and effectively by removing or minimizing the effect of such lifestyle factors one at a time through targeted preventive intervention.

MTHFR C677T Polymorphism and factor V Leiden mutation are not associated with recurrent spontaneous abortion of unexplained etiology in Japanese women.

To determine whether the C677T polymorphism of the methylenetetrahydrofolate reductase ( MTHFR) gene and the Leiden mutation of coagulation factor V (FV) are associated with recurrent spontaneous abortion (RSA) of unexplained etiology in Japanese participants, the genotypes of the two polymorphisms were determined and compared between cases of unexplained RSA and normal pregnant controls. Eighty-three Japanese participants, consisting of 45 women with explained RSA and 38 women with unexplained RSA, and 174 controls were recruited in the study. The frequencies of the T677 allele/TT genotype were not significantly different among women with explained RSA (35.6%/13.3%), women with unexplained RSA (34.2%/7.9%), primigravid controls (35.1%/11.7%), and multigravid controls (39.7%/16.5%). In the cases of unexplained RSA, the frequencies of the T677 allele and TT genotype tended to increase according to the number of previous spontaneous abortions, but the increase was without statistical significance: the frequencies of the T677 allele and TT genotype in women with two abortions were 18.2% and 0%, whereas in women with three abortions the frequencies were 38.0% and 9.5%, and in women with four or more abortions the frequencies were 50.0% and 16.7%, respectively. In addition, no Leiden mutation of FV was detected in the women with RSA or the controls. Neither T677 of the MTHFR nor the Leiden mutation of FV was associated with unexplained RSA in the Japanese population.

The egogram is a potent, independent risk factor for hypertension in pregnancy.

To assess the association between the egogram and hypertension in pregnancy (HP), a case-control study was carried out. Seventy-one HP cases, primiparous aged 20 to 34 years, and 109 controls, were enrolled among pregnant women who visited our hospitals for obstetrical care. Data from a self-administered questionnaire containing a Self Grow-Up Egogram (SGE) were subjected to univariate and multivariate analyses with prepregnancy body mass index (BMI) and angiotensinogen (AGT) genotype. The mean +/- standard error of total scores for the critical parent (CP) scale were 9.7 +/- 0.5 for cases and 8.3 +/- 0.3 for controls, those for the nurturing parent (NP) scale were 13.6 +/- 0.4 for cases and 13.4 +/- 0.3 for controls, those for the adult (A) scale were 11.3 +/- 0.5 for cases and 10.9 +/- 0.3 for controls, those for the free child (FC) scale were 12.3 +/- 0.3 for cases and 13.8 +/- 0.3 for controls, and those for the adapted child (AC) scale were 10.2 +/- 0.4 for cases and 8.5 +/- 0.4 for controls. A low FC scale score (FC < or = 10) and a high AC scale score (AC > 10) were significantly associated with HP ( p < 0.05; p < 0.01, respectively). In the multivariate analysis, FC < or = 10, AC > 10, prepregnancy BMI > or = 24, and homozygosity of the T235 allele genotype of the AGT gene were detected as the potent independent risk factors for HP. The odds ratios were 2.2, 2.8, 4.0, and 2.5, respectively. The present results suggest that a low FC score and a high AC score may be potent, independent risk factors for HP.

Insertion/deletion polymorphism of the angiotensin-converting enzyme gene and preeclampsia in Japanese patients.

To clarify whether the homozygous deletion (DD) genotype of angiotensin-converting enzyme gene ( ACE) is a genetic risk factor for preeclampsia in Japanese women, we performed ACE genotyping in patients with preeclampsia and healthy pregnant women, and analyzed the relationship between preeclampsia and ACE genotype, taking into account some well-known contributing factors for preeclampsia, such as primiparity, positive family history of hypertension, prepregnancy body mass index < 24, and heterozygosity and homozygosity of T235 (MT+TT) genotypes of the angiotensinogen ( AGT) gene. Among all of the subjects, the frequency of the DD genotype was not different between patients with preeclampsia and controls (16% and 12%, respectively). Regarding primiparity, prepregnancy body mass index < 24, and MT+TT genotypes of AGT, no significant differences in the frequency of the DD genotype of ACE were found between patients with preeclampsia and controls, although in a subgroup positive for family history of hypertension, the frequency of the DD genotype tended to be higher in patients with preeclampsia (25%) than in controls (8%; p = 0.061). Carrying the DD genotype may have some influence on the pathogenesis of preeclampsia, perhaps through effects on placental hypoxia or the interaction of hypertensive disease and atherosclerosis, although this influence may not be strong. Additional studies using a larger number of patients and analyses that include other genetic and environmental factors will be necessary to confirm these results.

The M235T variant of the angiotensinogen gene and the body mass index are useful markers for prevention of hypertension in pregnancy: a tree-based analysis of gene-environment interaction.

We sought to perform a tree-based analysis of lifestyle risk factors for hypertension in pregnancy (HP) with univariate and multivariate analyses. Seventy-eight HP patients and 199 normal controls were recruited from primiparous women 20 to 34 years of age. Data from angiotensinogen (AGT) genotyping and data from a self-administered questionnaire about lifestyle were subjected to univariate and multivariate analyses. By dividing the subjects into two subgroups--those who possessed "the TT genotype of AGT" and "body mass index (BMI) < 24" and those who did not--we were able to examine the acquired risk factors for HP during pregnancy in these two groups. Multivariate analysis selected "mentally stressful condition" and "no antenatal training during pregnancy" in the former group, and "poorly balanced diet" in the latter group. Determination of factors obvious before pregnancy, such as genotype or prepregnancy BMI, may be useful for devising effective individualized strategies for preventing HP.

An association between maternal smoking and preeclampsia in Japanese women.

In order to determine whether maternal smoking before or during pregnancy, or both, is associated with a reduced risk for preeclampsia in Japanese subjects, we conducted a case-control study that took other risk factors for preeclampsia into consideration. Seventy-one preeclampsia patients were matched with 142 controls for parity and age. Information from a self-administered questionnaire and clinical data such as maternal age, parity, family history of hypertension, prepregnancy body mass index (BMI), and pregnancy outcomes were analyzed. No significant difference was found between the groups in smoking rates before and during pregnancy (38.0 and 18.3% in preeclampsia patients and 38.0 and 16.9% in controls, respectively). However, classification of the subjects according to the presence of "prepregnancy high body mass (BMI > or = 24)" revealed a significant association between maternal smoking before pregnancy and preeclampsia in women with a prepregnancy high body mass (a smoking rate of 47.6% in patients with preeclampsia and 7.1% in controls, p < 0.05). This result suggests that there is a clear racial difference in the manifestation of preeclampsia with respect to the effect of smoking and that early intervention, particularly before pregnancy, to get obese women to stop smoking may be effective for preventing preeclampsia.

A1166C variant of angiotensin II type 1 receptor gene is associated with severe hypertension in pregnancy independently of T235 variant of angiotensinogen gene.

Hypertension in pregnancy (HP) is a multifactorial disease manifested due to a complex combination of environmental factors and several predisposing genes including factors in the renin angiotensin system. The aim of this study was to assess the association between the A1166C variant of the angiotensin II type 1 receptor (AT1) gene and severe HP. We carried out association studies and multivariate analyses including other candidate causal factors of HP such as the M235T variant of the angiotensinogen (AGT) gene, prepregnancy body mass index (BMI), and family history of hypertension in Japanese subjects. One hundred and fourteen patients with severe HP and 291 normal pregnancy controls were genotyped. Among primiparous subjects, the frequency of "AC+CC genotype of AT1" was significantly higher in severe HP than in the controls. A multivariate analysis with "AC+CC genotype of AT1" and "TT genotype of AGT" revealed that these were independently associated with primiparous severe HP. However, when "family history of hypertension" and "prepregnancy BMI > or =25" were added as factors examined in the multivariate analysis, only "TT genotype of AGT" and "family history of hypertension" were found to be independent potent factors. The present results suggest that the C1166 allele of the AT1 gene may be concerned with the predisposition to essential hypertension independently of the T235 allele of the AGT gene.

Association between a variant of the glutathione S-transferase P1 gene (GSTP1) and hypertension in pregnancy in Japanese: interaction with parity, age, and genetic factors.

Hypertension in pregnancy (HP), including preeclampsia (PE), is known to be a multifactorial disease. Recently, an Ile105Val variant of the glutathione S-transferase P1 gene ( GSTP1) was shown to be associated with PE in The Netherlands. We therefore performed an association study of the Ile105Val variant comparing 131 patients with HP and 327 normal pregnant controls in Japan. We analyzed the data in the context of other risk factors before pregnancy. The frequency of the Ile/Val+Val/Val genotype of the GSTP1 was not significantly different between the HP (26%) patients and the controls (28%). However, in primiparous patients, the frequency was significantly different in elderly pregnancy (63% in severe HP vs. 18% in controls; P < 0.05), in the subgroup with the MM+MT genotypes of the angiotensinogen gene (50% in severe HP vs. 26% in controls; P < 0.05), and in the subgroup with the GA+AA genotypes of the endothelial nitric oxide synthase gene (42% in severe HP vs. 13% in controls; P < 0.05). These results suggest that this variant of the GSTP1 may play a role in the manifestation of HP together with other independently and/or synergistically acting factors, particularly in primiparous pregnancy.

Dietary habits and risk of ossification of the posterior longitudinal ligaments of the spine (OPLL); findings from a case-control study in Japan.

The relation between dietary habits and the risk of ossification of the posterior longitudinal ligaments of the spine (OPLL) was investigated in a case-control study conducted in Japan from 1998 to 2001. Prevalent OPLL cases (n = 69) were identified and individually matched by age and sex with community controls (n = 138) randomly selected from the general population in Hokkaido. A self-administered food-frequency questionnaire was used to assess habitual dietary intake. The odds ratio (OR) and its 95% confidence interval (CI) were estimated, using conditional logistic regression models to compute the OR adjusted for a history of diabetes mellitus. We found that frequent consumption of pickles (salted products) was significantly associated with an increased risk of OPLL, with an adjusted OR of 1.6 (95% CI, 1.1 to 2.2). The adjusted OR for nondaily consumers of rice was 3.0 (95% CI, 2.4 to 3.7). Frequent consumption of chicken (adjusted OR, 0.5; 95% CI, 0.3 to 0.98) and soy foods (adjusted OR, 0.4; 95% CI, 0.2 to 0.7) was significantly associated with a decreased risk of OPLL. Our findings suggest that dietary habits may constitute independent risk factors for OPLL. Further studies will be needed to prospectively determine the relationship between dietary habits and OPLL risk.

Sleeping habit and other life styles in the prime of life and risk for ossification of the posterior longitudinal ligament of the spine (OPLL): a case-control study in Japan.

BACKGROUND: Although the average age of onset of ossification of the posterior longitudinal ligament of the spine (OPLL) is at around 50 years, the onset of the symptoms is insidious and the progression is very slow. The etiology of OPLL has not been elucidated in detail. Previous studies have suggested that a high-salt diet and low consumption of animal protein, glucose intolerance and high body mass are risk factors for OPLL. However, there is little information about the relationship between OPLL and life styles in the prime of life (between 30 and 50 years). METHODS: To facilitate early prediction and prevention of OPLL, we analyzed life styles such as sleeping habit, physical exercise, smoking, alcohol drinking and hangover in subjects in the prime of life. Self-administered questionnaires were obtained from patients with OPLL and their sex- and age-matched controls. Sixty-nine patients diagnosed with OPLL within 3 years previously and 138 sex- and age-matched controls without backbone diseases, randomly selected from participants in a health checkup in a local town, were enrolled. RESULT: Moderate amount of sleep (6-8 hours vs. 5 hours or shorter and 9 hours or longer; odds ratio [OR] = 0.18, 95% confidence interval [CI] = 0.06, 0.54) and a regular sleeping habit (i.e., going to bed and getting up at regular time) (OR=0.44, 95% CI=0.22, 0.90) were associated with a decreased risk of OPLL even after adjusting for other factors. On the other hand, moderate physical exercise (once a week or more v.s. less than once a week: OR=0.97, 95% CI=0.42, 2.26), smoking (OR=1.41, 95% CI=0.67, 2.97), drinking (OR=1.08, 95% CI=0.53, 2.20) and hangover (OR=1.12, 95% CI=0.43, 2.94) in the prime of life showed no correlation with risk of OPLL. CONCLUSION: Good sleeping habits in the prime of life may decrease the risk of OPLL.