Biomedical subjects
Sheila Williams
Publications and source records attributed to Sheila Williams.
Sexual orientation and self-harm in men and women.
OBJECTIVE: Recent studies of homosexual people have found higher rates of nonfatal suicidal behavior than among heterosexuals. The purpose of this study was to determine associations between self-harm and sexual orientation for men and women separately, defining sexual orientation by sexual attraction rather than by behavior. METHOD: In a birth cohort of 1,019 New Zealand young adults eligible to be interviewed at age 26 years, 946 participated in assessments of both sexual attraction and self-harm. RESULTS: Both women and men who had experienced same-sex attraction had higher risks of self-harm. The odds ratios for suicidal ideation in the past year were 3.1 for men and 2.9 for women. Odds ratios for ever having deliberately self-harmed were 5.5 for men and 1.9 for women. Men with same-sex attraction were also significantly more likely to report having attempted suicide. In both sexes, a greater degree of same-sex attraction predicted increasing likelihood of self-harm, with over one-third of men and women with persistent major same-sex attraction reporting this. Men with even a minor degree of same-sex attraction had high rates of self-harm and resulting physical injury. One-quarter of deliberate self-harm among men and one-sixth among women was potentially attributable to same-sex attraction. CONCLUSIONS: This study provides evidence of a link between increasing degrees of same-sex attraction and self-harm in both men and women, with the possibility of some difference between the sexes that needs to be explored further.
UL40-mediated NK evasion during productive infection with human cytomegalovirus.
Human cytomegalovirus (HCMV) exploits a range of strategies to evade and modulate the immune response. Its capacity to down-regulate MHC I expression was anticipated to render infected cells vulnerable to natural killer (NK) attack. Kinetic analysis revealed that during productive infection, HCMV strain AD169 first enhanced and then inhibited lysis of primary skin fibroblasts by a CD94/NKG2A(+)NKG2D(+)ILT2(+) NK line. The inhibition of cytotoxicity against strain AD169-infected fibroblasts was abolished by prior treatment of targets or effectors with anti-MHC I and anti-CD94 monoclonal antibodies, respectively, implying a CD94/HLA-E-dependent mechanism. An HCMV strain AD169, UL40 deletion mutant could not inhibit CD94/NKG2A(+) NK killing against skin fibroblasts. The contribution of UL40 to evasion of primary NK cells then was tested in a system where targets and effectors were MHC-matched. Primary NK cells activated with IFNalpha as well as cultured primary NK cell lines showed increased killing against DeltaUL40-infected fibroblasts compared with AD169-infected targets. This effect was abrogated by depletion of CD94(+) cells. These findings demonstrate that HCMV encodes a mechanism of evasion specifically targeted against a proportion of CD94(+) NK cells and show that this system functions during a productive infection.
Birth size, growth, and blood pressure between the ages of 7 and 26 years: failure to support the fetal origins hypothesis.
The "fetal origins hypothesis" asserts that birth weight is inversely related to later blood pressure. Data from a cohort of 891 infants born in Dunedin, New Zealand, in 1972-1973 whose blood pressure was measured at 2-year intervals from age 7 years to age 15 years and at ages 18 and 26 years were used to test this hypothesis. Three regression models based on standardized scores for weight and height were used. The first showed that at any of the ages at which the cohort was assessed, an increase in birth weight of one z score (one standard deviation) was commensurate with a decrease of 0.29 mmHg (95% confidence interval: -0.17, 0.76) in blood pressure. The second model showed that a one-z-score increase in weight between birth and a subsequent age was associated with an increase in systolic blood pressure of 0.96 mmHg (95% confidence interval: 0.53, 1.38). This estimate applied to all ages. The third model showed that the effect of an interaction between birth weight and later weight was not significant; thus, there was no evidence to suggest that children with a low birth weight who became overweight or obese had extra high blood pressure. Similar results were obtained for height. These results fail to support the fetal origins hypothesis.
Observations of summer sun protection among children in New Zealand: 1998-2000.
AIMS: To examine sun protection among New Zealand children (ten years and under) at beaches and playgrounds. METHODS: In the summers of 1998, 1999 and 2000, observations were made of 753 children at selected beaches and playgrounds in Dunedin and Hawkes Bay to determine the extent of sun protection. Parents/carers were also interviewed about sun protection. RESULTS: Across most body sites, levels of protection were high. Clothing and SPF15+ sunscreen were used most often, while the use of shade was relatively low. About four in every ten parents/caregivers were aware of the UV index or burn-time. Level of sun protection among children at beaches was best predicted by parent/carer's own level of protection, the child's perceived susceptibility to burning, and being a preschooler. CONCLUSIONS: Observed levels of sun protection among the children were high and most likely reflected an increased awareness among parents and carers of the social acceptability of protective behaviours. Nevertheless, opportunities to seek shade were limited, and the provision of shade at beaches and playgrounds represents an important next step in a community wide approach to sun protection.
Early growth, menarche, and adiposity rebound.
Adiposity rebound is thought to arise earlier in children with a high body-mass index (BMI) at age 3 years. To test this hypothesis we followed up a birth cohort. Our results indicate that earlier rebound arose in children who were tall at age 3 years, but that timing was not associated with BMI at age 3 years in boys, and arose later in girls with higher BMIs at age 3. Adiposity rebound also arose earlier in children whose parents had high rather than low BMIs. Magnitude of BMI at rebound was associated with height and BMI at age 3, and with parental BMI. There was a correlation between age at rebound and age at menarche, which suggests that timing of rebound is an indicator of physical maturity rather than obesity.
Relationship of serum ferritin with cardiovascular risk factors and inflammation in young men and women.
Elevated ferritin levels have been reported as a risk factor for coronary heart disease in Finnish and Italian studies. Studies in other populations have found no association between ferritin and cardiovascular disease raising the possibility of confounding with other cardiovascular risk factors. We determined ferritin levels, metabolic cardiovascular risk factors, C-reactive protein (CRP), anthropometric measurements and blood pressure in 815 men and women aged 26 years. In women serum ferritin correlated with CRP, waist measurement, body mass index (BMI), and triglycerides. In multiple regression analysis CRP alone was independently associated with serum ferritin. Serum ferritin in men correlated with waist measurement, BMI, triglycerides and high-density lipoprotein (HDL) cholesterol. After adjustment for the other variables, waist measurement was the only independent predictor of ferritin. Ferritin levels in young men and women are associated with obesity and serum triglycerides, HDL cholesterol in men and inflammation in women. Confounding may contribute to reports of associations between ferritin and cardiovascular disease.
Purchasing of cigarettes by New Zealand secondary students in 2000.
OBJECTIVE: To examine the prevalence of under-age sales of cigarettes to New Zealand secondary school students in 2000 and to identify correlates of buying cigarettes. METHOD: A randomly selected sample of 53 secondary schools from five geographic regions took part, and 2,896 Year 10 and Year 12 students completed a self-report questionnaire. RESULTS: Some 30.3% reported smoking during the past 30 days and 61.8% of these students usually obtained cigarettes by purchasing from shops, from other students or from someone else buying them on their behalf. Local corner stores and service stations were the most popular source. Buying cigarettes was associated with more frequent smoking, more money to spend, a higher school decile rating and higher proportion of schoolmates also purchasing. CONCLUSIONS: Prohibition of cigarette sales to minors needs much greater attention in NZ than it is receiving at present if smoking among young people is to be reduced.
High prevalence, persistent hazardous drinking among New Zealand tertiary students.
AIMS: To determine the prevalence of hazardous drinking and alcohol-related negative consequences in New Zealand tertiary students, and to identify predictors of hazardous drinking across a 6-month period. METHODS: A total of 1480 tertiary students living in halls of residence was surveyed at the start of the academic year, and a subsample of 967 students was followed up 6 months later. Questionnaire items included quantity and frequency of drinking, alcohol-related problems, use of other substances, and the Alcohol Use Disorders Identification Test (AUDIT). Drinking at follow-up was modelled using demographic characteristics, mental well-being, other substance use, alcohol-related problems, and hall drinking norms, measured at baseline. RESULTS: Among drinkers, mean (+/- SD) weekly consumption was 243 +/- 241 and 135 +/- 157 g of ethanol for males and females respectively. The majority of male (60.0%) and female (58.2%) drinkers typically consumed more than national safe drinking guidelines. Mean (+/- SD) AUDIT scores were 10.9 +/- 7.6 for males and 7.6 +/- 5.9 for females. After controlling for AUDIT scores at baseline, increased AUDIT scores at follow-up were higher with lower age, Maori ethnicity, smoking, cannabis use, high levels of alcohol-related negative consequences, and higher levels of drinking in the student's hall of residence. CONCLUSIONS: Hazardous drinking is widespread and persistent among students living in the halls of residence. There is a need for university alcohol policies and intervention approaches among New Zealand tertiary students.