Variation during the week in the incidence of acute myocardial infarction: increased risk for Japanese women on Saturdays

BACKGROUND

Variations in the incidence of acute myocardial infarction during the week may differ between and within communities, according to lifestyle.

OBJECTIVE

To identify potential triggering factors for acute myocardial infarction by examining variations in incidence in the days of the week within the Osaka area of Japan.

PATIENTS

Of 2511 consecutive patients in this region who were admitted to hospital for acute myocardial infarction between April 1998 and March 2001 and consented to take part, 2400 who had a definitely identified time of onset were enrolled.

RESULTS

For this group as a whole, no significant difference in incidence was noted between days of the week. However, in subgroup analyses women were shown to have significant variation through the week, peaking on Saturday with a 39% increase in relative risk (p = 0.037); working subjects showed a peak on Monday, with a 26% increase in relative risk (p = 0.038). Stratified analyses showed that in working men there was a prominent Monday peak in the onset of infarction, with a 30% increase in relative risk (p = 0.022), while in working women, there was no significant variation through the week.

CONCLUSIONS

Earlier findings of a Monday peak linked to increased physical and mental occupational stress are confirmed. There is also an increase in uncertain risk factors on Saturdays for Japanese women, possibly involving a stressful weekend burden for women. Confirmation of this finding in other communities may help identify triggers of acute myocardial infarction and be useful in prevention.

A49T, V89L and TA repeat polymorphisms of steroid 5alpha-reductase type II and breast cancer risk in Japanese women

BACKGROUND

Breast cancer is hormone related, as are cancers of the endometrium, ovary, and prostate. Several studies have suggested that higher extracellular levels of androgens are associated with breast cancer risk, while biological evidence indicates that androgens are protective. The codon 49 alanine to threonine substitution (A49T), codon 89 valine to leucine substitution (V89L) and TA repeat polymorphisms of the steroid 5alpha-reductase type II (SRD5A2) gene are considered functional with respect to enzyme activity converting testosterone into dihydrotestosterone. To test the hypothesis that these three polymorphisms are associated with risk of breast cancer, a case-control study was conducted with patients of Aichi Cancer Center Hospital.

METHODS

The cases were 237 patients histologically diagnosed with breast cancer, and the controls were 185 noncancer outpatients. DNA from peripheral blood was genotyped by PCR methods.

RESULTS

The threonine allele of A49T was not found in our subjects. Compared with the V/V genotype of V89L, the L/L genotype was associated with a decreased risk (crude odds ratio [OR] = 0.61, 95% confidence interval [CI] = 0.36-1.05). This was also the case for the TA(9/9) genotype, with an OR of 0.58 (95% CI = 0.13-2.63) relative to TA(0/0). Among women with the TA(0/0) genotype, however, the OR for the L/L genotype was 0.46 (95% CI = 0.24-0.88) compared with the V/V genotype, and those with the V/V and TA(0/0) genotypes had the highest risk. The haplotype with the L and TA(9) repeat alleles was not found.

CONCLUSION

This study is the first to our knowledge focusing on Japanese women, suggesting that SRD5A2 polymorphisms might have an association with breast cancer risk. Further large-sample studies will be required to confirm the association and to assess any interactions with environmental factors.

Human papillomavirus infection and risk determinants for squamous intraepithelial lesion and cervical cancer in Japan

A case control design was used to investigate human papillomavirus (HPV) prevalence and risk factors associated with development of cervical squamous intraepithelial lesion (SIL) and cervical cancer (CC) in Japan. One hundred and twenty-three women with histologically confirmed SIL or CC were compared to a control group of 778 cytologically normal women. With the use of a polymerase chain reaction (PCR)-based method for detection of low-risk (types 6 and 11) and high-risk (types 16, 18, 31, 33, 35, 52 and 58) HPVs, a high prevalence of HPV infection was observed in smokers among the controls. Logistic regression analysis demonstrated that high-risk HPV infection was the most significant risk determinant for LSIL (OR=9.4, 95% CI=4.5-19), HSIL (OR=77, 95% CI=28-217) and CC (OR=97, 95% CI=35-269). It also showed that unmarried women, women married for 5 to 19 years and smokers represented high risk groups for SIL, while smokers and women with a history of many pregnancies/parities had increased risk for CC. Smoking was the only HPV infection-independent factor for CC, suggesting that smoking may have a carcinogenic effect on the cervix. Since neither history of other cancer nor family cancer history was associated with SIL or CC, genetic factors appear to play little role in cervical carcinogenesis. The risk for cervical neoplasia due to HPV infection increased after marriage in Japan, suggesting a role for husbands as carriers of HPV transmission. Protection from high-risk HPV infection may be of greatest importance for prevention of cervical cancer.

Detection of human papillomavirus types 6/11, 16 and 18 in exfoliated cells from the uterine cervices of Japanese women with and without lesions

Human papillomavirus (HPV) infection of the uterine cervices of Japanese women with and without lesions was identified by the filter in situ hybridization method. Exfoliated cervical cells from 23 cervical papillary condylomas, 70 cervical intraepithelial neoplasia (CIN) grade I/II, 26 CIN III, 31 invasive cervical cancers and 666 cervices without evidence of disease (including 53 pregnant women) were tested for the presence of HPV types 6/11, 16 and 18. The positive rates for the detection of HPV types 6/11, 16 and 18 DNA were 47.8%, 26.1% and 8.7% in cervical condylomas, 5.7%, 15.7% and 8.6% in CIN I/II, 0, 34.6% and 0 in CIN III, 3.2%, 38.7% and 9.7% in invasive cervical cancers and 0.9%, 1.8% and 0.6% in the control cervices. These data suggest that, in Japan, HPV6/11, HPV16 and HPV18 infections are also prevalent in cervical cells with normal phenotype, and the type of HPV infection of the uterine cervix is related to the histological diagnosis.