Despite recent successes in cloning various animal species, the use of somatic cells as the source of donor nuclei has raised many practically relevant questions such as increased abortion rates, high birth weight and perinatal death. These anomalies may be caused by incomplete epigenetic reprogramming of donor DNA. Genome-wide demethylation occurs during early development, 'erasing' gamete-specific methylation patterns inherited from the parents. This process may be a prerequisite for the formation of pluripotent stem cells that are important for the later development. Here, we provide evidence that cloned bovine embryos may have impaired epigenetic reprogramming capabilities. We found highly aberrant methylation patterns in various genomic regions of cloned embryos. Cloned blastocysts closely resembled donor cells in their overall genomic methylation status, which was very different from that of normal blastocysts produced in vitro or in vivo. We found demethylation of the Bov-B long interspersed nuclear element sequence in normal embryos, but not in cloned embryos, in which the donor-type methylation was simply maintained during preimplantation development. There were also significant variations in the degree of methylation among individual cloned blastocysts. Our findings indicate that the developmental anomalies of cloned embryos could be due to incomplete epigenetic reprogramming of donor genomic DNA.

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nurses who were 30 yr old or more. WHR in female nurses increased slightly according to increasing duration of shift work. Fasting blood sugar was not significantly associated with the duration of shift work in either sex regardless of age-group. These results suggest an association between shift work duration and the metabolic risk factors of cardiovascular disease. The number of shift workers has increased in some branches of industry, especially manufacturing. The total number of night shift and other types of shift workers ranges from 15 to 20% of the total workforce in most European Community countries 1) , and is 20% in the United States 2) . In Asian countries, the numbers of shift workers are gradually increasing, and it has been estimated that about 6% of the total work force in Thailand, 10% in the Philippines, and 14% in Peru were involved with shift work during the 1980's 3) . Nationwide surveys showed the percentages of shift workers were 32% in Singapore (1991) 4) and 25% in Korea (1994) 5) . There have been several reports on the incidence of cardiovascular diseases (CVD) among shift workers. Most of these studies found significant associations between CVD and shift work 1,6) . The longer the shift work duration, the higher the risk of CVD 7) . The population etiologic fraction of shift work on cardiovascular disease has been estimated to be approximately 7%, due to the high proportion of shift workers in the workforce 8) . One of the mechanisms proposed for this association is a mismatch of circadian rhythms, through which metabolic disturbances could occur 9) .A recent epidemiologic study reported that obesity, high triglycerides (TG) and low concentrations of high-density lipoprotein (HDL) cholesterol appear to cluster together more often in shift workers than in day workers 9) . On the other hand, there is strong evidence showing that the metabolic syndrome, which is composed of obesity, Received Dec 16, 2002; Accepted Nov 22, 2004 conducted this study to examine the relationship between shift work duration and the metabolic risk factors of cardiovascular disease among shift workers. The study population consisted of 226 female hospital nurses and 134 male workers at a firm manufacturing diapers and feminine hygiene materials, whose mean ages were 28.5 yr for the nurses and 29.1 yr for the male workers. The fasting blood sugar level, serum cholesterol, blood pressure, height and weight, waist and hip circumferences (only for the nurses), and numbers of walks during work (as a measure of physical activity) were measured. Using the Karasek's job contents questionnaire, job stress was assessed. Information about the years of work, shift work duration, past medical and behavioral history, including smoking, was obtained by a self-administered questionnaire. With definitions of hypertension as systolic blood pressure (SBP) ≥160 or diastolic blood pressure (DBP) ≥90 mmHg occurring at least once, hypercholesterolemia as serum total cholesterol ≥240 mg/dl, obesity as body mass index (BMI) ≥25 kg/m ...

The functional and evolutionary significance of DNA methylation in insect genomes remains to be resolved. Nasonia is well situated for comparative analyses of DNA methylation and genome evolution, since the genomes of a moderately distant outgroup species as well as closely related sibling species are available. Using direct sequencing of bisulfite-converted DNA, we uncovered a substantial level of DNA methylation in 17 of 18 Nasonia vitripennis genes and a strong correlation between methylation level and CpG depletion. Notably, in the sex-determining locus transformer, the exon that is alternatively spliced between the sexes is heavily methylated in both males and females, whereas other exons are only sparsely methylated. Orthologous genes of the honeybee and Nasonia show highly similar relative levels of CpG depletion, despite ~190 My divergence. Densely and sparsely methylated genes in these species also exhibit similar functional enrichments. We found that the degree of CpG depletion is negatively correlated with substitution rates between closely related Nasonia species for synonymous, nonsynonymous, and intron sites. This suggests that mutation rates increase with decreasing levels of germ line methylation. Thus, DNA methylation is prevalent in the Nasonia genome, may participate in regulatory processes such as sex determination and alternative splicing, and is correlated with several aspects of genome and sequence evolution.

The incidence of occupational injuries and diseases associated with industrialization has declined markedly following developments in science and technology, such as engineering controls, protective equipment, safer machinery and processes, and greater adherence to regulations and labor inspections. Although the introduction of health and safety management systems has further decreased the incidence of occupational injuries and diseases, these systems are not effective unless accompanied by a positive safety culture in the workplace. The characteristics of work in the 21st century have given rise to new issues related to workers' health, such as new types of work-related disorders, noncommunicable diseases, and inequality in the availability of occupational health services. Overcoming these new and emerging issues requires a culture of prevention at the national level. The present paper addresses: (1) how to change safety cultures in both theory and practice at the level of the workplace; and (2) the role of prevention culture at the national level.

Presuming that overtime work may associate with chronic fatigue and then decrease cardiovascular function, this report was prepared to find out the definite positive relationship between long working hours and subjective fatigue complaints. We analysed the data of a field survey of 238 men who were working at the department of research & development of three electronics manufacturing companies in S. Korea. The field survey consisted of self-report questionnaires on the working hours, health conditions, and fatigue. For data analysis, the subjects were divided into 3 groups on the criteria of 60 and 70 working hours per week: less longer (LLWH), longer (LWH), and more longer (MLWH) working hour groups. We compared the age-adjusted mean % scores of fatigue complaints among LLWH, LWH, and MLWH. The rate of complaints of subjective fatigue before going to work for LWH and MLWH tended to be significantly higher than those for LLWH. Hence, we conclude that the questionnaire on the subjective fatigue complaints is a good screening tool for early detection of cumulative fatigue due to chronic job stress such as long working hours.

BackgroundThe aim of this study was to evaluate the quality of the Second Korean Working Conditions Survey (KWCS), focusing on its validity and reliability.MethodsThe external validity was evaluated by the assessment of sampling procedures and the response rate, in order to investigate the representativeness of the sample. The content validity was evaluated by the assessment of the development of the questionnaire, and the consistency of questions for the selected construct. The test-retest method was used to evaluate the reliability by means of a phone call survey of 30% of the respondents, who were randomly selected. The respondents' satisfaction regarding the survey procedures and interview time were analyzed to evaluate the quality of survey data.ResultsThe external validity was assured by an acceptable sampling procedure, rigid multi-stage stratified cluster random sampling. The content validity was also guaranteed by a reasonable procedure for the development of the questionnaire with a pretest. The internal consistency of the questions for work autonomy was maintained, with 0.738 of Cronbach's alpha. The response rate of 36% was lower than that of the European Working Conditions Survey (EWCS), with a contact rate of 66%, compared to 76% for the EWCS. The matching rates of the five retested questions were more than 98% reliable.ConclusionThe quality of the second KWCS was assured by the high external and content validity and reliability. The rigid sampling procedure and development of the questionnaire contributed to quality assurance. The high level of reliability may be guaranteed by the sophisticated field survey procedures and the development of a technical manual for interviewers. The technical strategies for a high response rate should be developed for future surveys.

Most tumors express an array of antigens that act as targets for their immune-mediated destruction, and a number of potential therapies have emerged to exploit this (22). The immunotherapeutic strategy used to induce an immune response against tumors is quite attractive because it offers the potential for a high level of tumor-specific cytotoxicity, minimal side effects, and a durable effect.Dendritic cells (DCs) are the most potent antigen-presenting cells (APCs) in the induction of primary immune responses (29, 33). Because of their central role in controlling cell-mediated immunity, DCs hold much promise as cellular adjuvants in therapeutic cancer vaccines. DC-based immunotherapy has been reported to induce strong antitumor immune responses in animal experiments and in selected clinical trials involving malignant gliomas (2, 11, 36). However, its clinical effects on patients with malignancies have not been up to the expectations because of immune tolerance, the sheer physical burden of tumor antigens, and the mechanisms of tumor escape from the immune surveillance system, among others (10,20).Calreticulin (CRT) acts as a danger signal for DCs, allowing them to phagocytose tumor cells and to prime tumor antigenspecific cytotoxic T cells (CTLs) (12). It was recently reported that CRT exposure on the surfaces of dying tumor cells may determine whether chemotherapy is immunogenic (26). The capacity of chemotherapies to induce immunogenic tumor cell death is associated with the expression of CRT on the tumor cell surface. Furthermore, it was shown with an animal tumor model that the provision of CRT from an exogenous CRT exposure source as enforcement for endogenous CRT exposure could improve the efficacy of chemotherapy by stimulating antitumor immunity (27). Thus, whether chemotherapy triggers such an immunogenic effect depends on the exposure of CRT on the cell surface. The use of multimodality treatments that combine conventional antitumor therapies with immunotherapy, such as vaccination with DC-based vaccines, has emerged as a potentially plausible approach to the treatment of tumors (3, 5). We previously reported that the use of a multimodality treatment regimen with a DC-based vaccine in combination with the chemotherapeutic agent temozolomide (TMZ) leads to enhanced tumor-specific CTL responses and enhanced antitumor effects, resulting in a cure rate higher than that achieved with either a DC-based vaccine or TMZ alone (17,28). However, the immunological factors relating to the antitumor effect of TMZ chemoimmunotherapy in a murine glioma model are still unclear.