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Biomedical subjects

T Dwyer

Publications and source records attributed to T Dwyer.

At least 55 records · Page 3Linked to original sources
PubMed1999

Frequency of headaches associated with the cervical spine and relationships with anthropometric, muscle performance, and recreational factors.

OBJECTIVE: To investigate headache specifically associated with the cervical spine, and factors associated with it. DESIGN: Cross-sectional, population-based observational study. SETTING: Two agriculturally based municipalities in southern Tasmania, Australia. PATIENTS: Four hundred fifty adults were randomly selected from electoral rolls; after refusals and exclusions, 427 subjects participated. OUTCOME MEASURE: For analysis, subjects were divided into three groups: those who did not have a particular type of headache in the previous month, those reporting fewer than two headaches of this type for the month (occasional headache), and those reporting two or more (frequent) headaches of this type in the month. STUDY FACTORS: Information collected by questionnaire and by objective measurement on anthropometric and functional measurements, wearing glasses or dentures, usual occupation, and usual recreational activities. RESULTS: The monthly prevalence of frequent headaches associated with the cervical spine was 28.3% (95% confidence interval [CI], 24.2-32.9), and another 35.4% (30.9-40.1) of subjects had these headaches occasionally. The frequency of headache occurrence was associated with a difference between front and back neck length of 2 cm or more. Occasional participation in recreational sport by men and wearing glasses by women were significant predictors of headache. CONCLUSION: Headaches of this type were more frequent in subjects with a long anterior neck length relative to their posterior neck length, particularly if they occasionally participated in recreational sports (men) or wore glasses (women).

Adult↗
PubMed1999

Vitamin D levels in prepubertal children in Southern Tasmania: prevalence and determinants.

OBJECTIVE: To describe the prevalence and determinants of 25-hydroxy D3(25(OH)D) in children. DESIGN: Cross-sectional study. SETTING: Southern Tasmania between June and November 1997. SUBJECTS: Two hundred and one 8-y old male and female children taking part in a cohort study whose principal endpoints were blood pressure and high-density lipoprotein (HDL) cholesterol. RESULTS: The mean 25(OH)D level was 79 nmol/l (s.d. 29.5, median 73, range 12-222). Boys had higher levels than girls (82.1 vs 72.8 nmol/l, P=0.02). 25(OH)D was associated with sunlight exposure in winter school holidays (r=0.20, P=0.005) and winter weekends (r=0.16, P=0.02), the month after school holidays (87.5 vs 69.5 nmol, P<0.0001) and body mass index (r=-0.23, P=0.001). Dietary intake of vitamin D was low (mean 40 IU/day, range 5.2-384) and was not associated with 25(OH)D levels (r=0.01, P=0.91). Variation in skin melanin density was weakly associated with 25(OH)D (r=0.09, P=0.19). CONCLUSIONS: Sunlight is the major determinant of vitamin D stores in our population. Neither variation in skin type within Caucasians nor diet modified this association to any significant extent. Extrapolation of these findings to sunlight bone mass associations in a very similar population suggests that a minimum level of around 50 nmol/l in the population is required for optimal bone development in prepubertal children but this needs to be confirmed with further controlled trials of vitamin D supplementation and bone mass. SPONSORSHIP: Arthritis Foundation of Australia, Roche Pharmaceuticals.

Body Mass Index↗
PubMed1999

Short-term morbidity and infant mortality among infants who slept supine at 1 month of age--a follow-up report.

Following evidence that prone sleeping is causally related to sudden infant death syndrome (SIDS), intervention campaigns to avoid prone sleeping in many countries have led to a large reduction in SIDS and total infant mortality. The supine position has been recommended for healthy infants in several countries. The objective of this report was to determine how usual sleep position at 1 month relates to morbidity indicators at 1 month and 12 weeks and to SIDS and postneonatal mortality using a prospective population-based live birth cohort in Tasmania, Australia. Eligible infants were the one-fifth of Tasmanian live births at higher risk of SIDS using a perinatal score. From 1 January 1988 to 31 December 1995, 9826 (89% of eligible) infants participated in the home interview. Fifty-three eligible infants died of SIDS, 51 (96%) with hospital interview data and 35 (81% of those eligible for home visit) with home visit data. The main outcome measures were SIDS, postneonatal mortality and parentally reported infant morbidity. The postneonatal mortality rates (cases per 1000 live births) by usual sleep position at 1 month of age were supine 1.60 [95% CI 0.04, 8.87], side 2.87 [1.79, 4.35], prone 10.27 [5.62, 17.18] and other (including no usual position) 6.37 [0.16, 34.98]. None of the study infants who slept supine died of SIDS at a later time. Of 25 morbidity indicators studied, only noisy breathing was increased for supine compared with side-sleeping babies. In this study, there was no evidence to suggest that supine sleeping at 1 month of age was associated with an increase in important short-term morbidity or postneonatal mortality. These findings provide further support for the recent recommendations of the American Academy of Pediatrics that healthy infants should preferably sleep in the supine position.

Analysis of Variance↗
PubMed1999

Water fluoridation, bone mass and fracture: a quantitative overview of the literature.

OBJECTIVE: To use the technique of meta-analysis to address the following research questions: Is water fluoridation associated with altered fracture risk at a population level and are the differences between studies consistent with confounding or chance variation between studies? METHOD: The data sources utilised were Medline 1966-97, reviews and bibliographies. The search terms were fluoridation, bone mass and/or fracture. We included all observational studies published in English relating water fluoridation to bone mass and/or fracture in the initial assessment. RESULTS: Water fluoridation had no evident effect on fracture risk (RR 1.02, 95% CI 0.96-1.09, n = 18 studies). There was marked heterogeneity between studies which could be explained, in part, by the combination of gender, urbanicity and study quality (R2 0.25, p = 0.05, weighted analysis). CONCLUSIONS: Water fluoridation both at levels aimed at preventing dental caries and, possibly, at higher naturally occurring levels appears to have little effect on fracture risk, either protective or deleterious, at a population level. The small effect on bone mass seen in studies performed at the individual level is consistent with this finding. Variation between studies is also likely to be due to differences in the distribution of other recognised fracture risk factors between different populations. Confirmation of these findings is required in large studies performed at the individual level.

Analysis of Variance↗
PubMed1999

Relationship between early life respiratory illness, family size over time, and the development of asthma and hay fever: a seven year follow up study.

BACKGROUND: The timing and mechanism of the inverse association between increasing sibling number and atopic disease are not yet understood. A study was undertaken to examine how family size at birth predicts early respiratory illness, to report the association between infant respiratory illness and childhood atopic disease, and to determine whether the protective effect of large family size operates during infancy or later childhood. METHODS: A prospective follow up study was carried out on 863 children (78%) of 1111 participants in the Tasmanian Infant Health Survey performed in 1988. In 1988 household size and history of respiratory illness were obtained by parental interview at home (median age 35 days) and later by telephone (median age 85 days). In 1995 asthma, hay fever, and household size were assessed by parental questionnaire in a large cross sectional survey. RESULTS: In 1988 increasing resident number (per resident) (adjusted odds ratio (AOR) 1.17 (95% CI 1.05 to 1.31)) and resident density (AOR 1.77 (95% CI 1.07 to 2.94)) were related to parental report of an upper respiratory tract infection (URTI) by one month of age. Children with a reported URTI by home interview were more likely to have subsequent asthma (adjusted relative risk (ARR) 1.27 (95% CI 1.05 to 1.53)). The association between lower respiratory tract infection (LRTI) at telephone interview (relative risk (RR) 1.34 (95% CI 1.02 to 1.75) and asthma was reduced after adjustment for family history of asthma (ARR 1.27 (95% CI 0.98 to 1.66)). Antibiotic use by home interview was not associated with subsequent asthma or hay fever. Indicators of family size in 1988 were associated with hay fever but not asthma but, in contrast, resident number in 1995 was inversely associated with asthma (AOR 0.82 (95% CI 0.72 to 0.92) per resident) and hay fever (AOR 0.82 (95% CI 0.71 to 0.96) per resident). Children with no siblings were at risk for current asthma, particularly if symptoms began after the age of four (RR 2.81 (95% CI 1.36 to 5.84)). CONCLUSIONS: The apparent protective effect of large household size and asthma could not be explained by an increase in reported early respiratory illness. The first year of life may not be the most critical time for the protective effect of large household size to be mediated in relation to asthma, but this effect occurred by the seventh year of life.

Adult↗
PubMed1999

Maternal smoking during pregnancy, growth, and bone mass in prepubertal children.

There have been no studies of smoking during pregnancy and bone mineralization in children. The objective of this population-based longitudinal study was to determine whether maternal smoking during pregnancy is associated with bone mass and other growth variables in prepubertal children. We studied 330 8-year-old male and female children representing 47% of those who originally took part in a study of risk factors for Sudden Infant Death Syndrome in 1988. The main outcome measures were bone mineral density measured by a Hologic QDR2000 densitometer: birth weight, placental weight, height, and weight. Maternal smoking during pregnancy was associated with deficits in growth with these children having lower height (-1.53 cm, 95% confidence interval [CI] -3.03 to -0.03) and a trend to lower weight (-1.35 kg, 95% CI -2.75 to 0.11) at age 8. Furthermore, there was a disproportionate deficit in bone mass such that those children whose mothers smoked during pregnancy had lower size adjusted bone mass at the lumbar spine (-0.019 g/cm2, 95% CI -0.033 to -0.005) and femoral neck (-0.018 g/cm2, 95%CI -0.034 to -0.002) but not total body (-0.005 g/cm2, 95% CI -0.015 to 0.005). This association was only present for children born at term. Mothers who smoked during pregnancy also had lower placental weight (- 56 g, 95% CI -95 to -17), and further adjustment for placental weight led to nonsignificant results for smoking with both growth and bone parameters, suggesting that these associations may be mediated through placental size and function. Maternal smoking habit in 1996 was not significantly associated with bone mass at any site. In conclusion, this study has demonstrated a long-term negative association between maternal smoking during pregnancy and both growth and bone mass in children born at term, and suggests that the timing of exposure rather than the dose or duration is critical. If these associations are present in other populations and they persist until the attainment of peak bone mass, then our findings suggest that osteoporosis prevention programs should start very early in the life cycle.

Birth Weight↗
PubMed1999

Utility of the structured inventory of malingered symptomatology in identifying persons motivated to malinger psychopathology.

The Structured Inventory of Malingered Symptomatology (SIMS) is one of a number of recently developed instruments designed to identify persons exaggerating and/or fabricating psychiatric and cognitive symptomatology. Preliminary analog research indicated that the SIMS showed some promise as a screening device for identifying malingerers. This study examined the utility of the SIMS for identifying malingerers and, more importantly, its ability to distinguish truly symptomatic persons from persons fabricating symptomatology. In a sample of 197 participants who completed the SIMS and Symptom Checklist-90-Revised (SCL-90-R) under both honest and malingering instructional sets, sensitivity and specificity rates were generally high for the SIMS Total score and subscales. However, moderate correlations with the SCL-90-R were obtained in this sample, and specificity rates were lowest among a subset of participants reporting clinically significant levels of distress; both findings raise concerns regarding the potential for high false positive rates among clinical populations. Implications for clinical forensic practice are discussed and recommendations for future research are offered.

Adult↗
PubMed1998

Autoantibodies to glutamic acid decarboxylase and phenotypic features associated with early insulin treatment in individuals with adult-onset diabetes mellitus.

We investigated the association of serum antibodies to glutamic acid decarboxylase (GADab) with early start of insulin treatment (< or = 1 year from diagnosis, or < or = 2 years from diagnosis) using data from a representative sample of 374 adult-onset insulin-treated individuals from the Tasmanian Diabetes Register. Furthermore, we examined whether this association was stronger than the phenotypic characteristics (age at diagnosis, sex, family history of diabetes, level of obesity, duration of diabetes) often used for diabetes classification. In this cohort, 35.9% of males and 38.5% of females were GADab positive. Within the first year from diagnosis, 78.4% of GADab positive people compared to 44.0% of GADab negative people (p < 0.001) had started insulin treatment. Univariate associations with insulin treatment < or = 1 year from diagnosis included GADab positivity, no family history of diabetes, lower BMI for men, and GADab positivity and lower BMI for women. In multivariate models, significant associations with insulin treatment < or = 1 year from diagnosis included a family history of diabetes (OR = 0.47, 95% CI = 0.23-0.95) and GADab positivity (OR = 2.19, 95% CI = 1.01-4.73) for men, but only GADab positivity (OR = 7.53, 95% CI = 3.09-18.30) for women. Age at diagnosis was not associated with insulin treatment < or = 1 year or < or = 2 years from diagnosis for either sex. These findings indicate that a positive GADab test result is strongly associated with start of insulin treatment within 1 or 2 years from diagnosis, more so than characteristics such as level of obesity and age at diagnosis.

Adult↗
PubMed1998

Determinants of dust mite allergen concentrations in infant bedrooms in Tasmania.

BACKGROUND: High exposure to house dust mite allergen during the first year of life has been found to increase the risk of subsequent asthma and mite sensitization. Environmental factors, home construction and cleaning methods used are associated with levels of dust mites in the home. OBJECTIVE: To investigate determinants of levels of Der p 1 and Der f 1 mite allergens in homes of infants in southern Tasmania. METHODS: Dust samples were collected from 72 homes of infants participating in the Tasmanian Infant Health Survey (TIHS). The Der p 1 and Der f 1 allergen concentrations in these samples were measured. The TIHS interviewers obtained information from the mothers of the infants via a questionnaire, observed specified aspects of the home environment, and took readings of bedroom temperature and humidity. The effect of each item on allergen concentration in dust from bedroom floors was examined in a variety of ways. Those items which in this study appeared to be significantly related to allergen concentrations plus items which in other studies have been found to be related to allergen concentrations were then investigated further in multivariate models. RESULTS: Der p 1 allergen concentration (microg/g) and density (microg/m2) in dust from bedroom floors were found to be related to several home environment factors. In the univariate analyses, indoor humidity, 24 h maximum temperature, number of residents and a combination of floor covering and cleaning methods appeared to have a significant effect on allergen levels. These factors remained important in the multivariate model except that indicators for mould in the bathroom and drying washing on an outside line replaced indoor humidity. CONCLUSION: Features related to home dampness, the number of residents and floor covering and cleaning were major determinants of Der p 1 levels in the bedrooms studied.

Allergens↗
PubMed1998

Microalbuminuria is positively associated with usual dietary saturated fat intake and negatively associated with usual dietary protein intake in people with insulin-dependent diabetes mellitus.

Microalbuminuria has a cumulative incidence of > 30% in persons by 25 y duration of insulin-dependent diabetes mellitus (IDDM) and is a strong predictor of renal disease and mortality. Although improved glycemic control, maintenance of normal blood pressure, and use of angiotensin-converting enzyme inhibitors are important strategies to avoid developing microalbuminuria, dietary macronutrient intake may also play a role. A cross-sectional population-based study of Tasmanian adults with IDDM and no previous diagnosis of microalbuminuria was conducted by measuring usual dietary macronutrient intake with a food-frequency questionnaire and defining microalbuminuria as an average urinary albumin excretion rate between 20 and 200 micrograms albumin/min in at least two of three timed overnight urine collections. After sex, age, duration of diabetes, daily number of insulin injections, body mass index, glycated hemoglobin, serum high-density-lipoprotein cholesterol, frequency of exercise, and smoking status were adjusted for, the adjusted odds ratio for microalbuminuria for the highest quintile of energy-adjusted usual saturated fat intake compared with the lowest quintile was 4.9 (95% CI: 1.2, 20.0; P = 0.03). The adjusted odds ratio for microalbuminuria for the highest quintile of energy-adjusted usual protein intake compared with the lowest quintile was 0.10 (95% CI: 0.02, 0.56; P = 0.01). There was no significant association between microalbuminuria and energy-adjusted carbohydrate intake, energy-adjusted monounsaturated fat intake, or energy-adjusted polyunsaturated fat intake.

Adult↗
PubMed1998

Bicycle injuries: road trauma is not the only concern.

Data on bicycle injury presentations at a public hospital emergency department for 1991-95 inclusive were analysed to determine the nature and extent of bicycle injuries in the community. There were 599 bicycle injury presentations during the study period, representing more than 2.0% of all injury-related presentations to the emergency department. The main outcome measures were severity and type of injury. Distribution by gender, age, helmet use (1991 and 1992 only), location and mechanism was examined. Rider-only injuries (falls or collisions with stationary objects) accounted for 79.3% of all presentations with only 5.2% due to collisions on a public road or footpath with other moving traffic. Of all injuries where a location was determined, 61.6% occurred in off-road locations. There was little difference in the overall proportions of hospital admissions from injuries on-road (12.4%) and off-road (9.0%). Cyclists injured in on-road collisions with traffic had a higher proportion of hospital admissions (40.0%) than those injured on-road by other mechanisms (7.6%). Children under 10 years of age who had been riding without a helmet suffered a much higher proportion of injuries to the head (53.2% of all injuries) than older cyclists riding without a helmet (19.4%). The majority (83.1%) of head injuries in children under 10 years of age occurred off-road and helmet use was lowest in this group (28.6%). Given previous evidence that helmet use can prevent head injuries, strategies to increase helmet use among cyclists, particularly young children, while riding both on and off-road, should be given a high priority. Rider-only injuries are also an important public health issue.

Accidents, Traffic↗
PubMed1998

Cross sectional study of the relation between sibling number and asthma, hay fever, and eczema.

OBJECTIVES: To document the relation between sibling number and atopic disease, and to assess the contribution of possible confounding factors to the protective effect of siblings in relation to asthma and hay fever. DESIGN AND SUBJECTS: Cross sectional survey by parental questionnaire in Tasmania, Australia, on 6378 children (92% of those eligible) who reached 7 years of age during 1995. METHODS: Exercise challenge lung function testing was conducted on 428 children. Analyses reported were conducted on singleton births only (n = 6158). RESULTS: The prevalences of a history of asthma ever, hay fever, and eczema were 27%, 19%, and 22%, respectively. Asthma and hay fever, but not eczema, were inversely related to sibling number, with evidence of a dose-response trend. The mean age at onset for asthma or wheezy breathing decreased as the number of siblings increased. The inverse association between sibling number and asthma or hay fever persisted after adjustment for several confounders, such as parental smoking or breast feeding, but did not persist after adjustment for household size in 1995. CONCLUSIONS: The protective effect of high sibling number could not be separated from household size at age 7, and it appears to be operating after birth and influences the age at onset of asthma symptoms. Further work to increase knowledge of how the protective effect of the presence of siblings works might have important implications for the understanding of the pathogenesis of asthma.

Age of Onset↗
PubMed1998

Bone mass in prepubertal children: gender differences and the role of physical activity and sunlight exposure.

Retrospective studies have suggested that the prepubertal years may be an important window of opportunity to increase bone mass, but there have been few direct studies and little exploration of gender differences in this age group. In this study, we report the associations among physical activity measures, sunlight exposure, body composition, and bone mass in 8-yr-old children. We studied 330 children in 1996 (115 girls and 215 boys; response rate, 60%) who had previously taken part in a cohort study of cot death in 1988. They had measurement of anthropometrics (height, weight, and body composition), sunlight exposure (by questionnaire), and physical activity [questionnaire, muscle strength by dynamometry, and bicycle ergometric physical work capacity at a pulse of 170 beats/min (PWC170)]. Bone mineral density (BMD) was assessed at the spine, femoral neck, and total body by a Hologic QDR2000 densitometer. In females only, PWC170 [hip, 2.4%/quartile (95% confidence interval (CI), 0.3-4.5); spine, 1.7%/quartile (95% CI, 0.0-3.4); size adjusted] was associated with BMD, whereas in males only, BMD was associated with both sports participation (hip, 4.2% (95% CI, 1.1-7.3); spine, 4.3% (95% CI, 0.9-7.7)] and muscle strength [hip, 1.7%/quartile (95% CI, 0.0-3.4); but not spine; size adjusted]. Winter sunlight exposure was associated with BMD in girls [hip, 2.9%/category (95% CI, 0.7-5.0); spine, 3.6%/category (95% CI, 1.4-5.8)], but not in boys [hip, 0.3%/category (95% CI, -1.4 to +2.0); spine, 1.4%/category (95% CI, -0.7 to +3.5)]. Males and females were very similar in body size. However, males had higher size-adjusted BMD at the hip (9.6%; 95% CI, 6.9-14), whereas females had higher size-adjusted BMD at the spine (3.2%; 95% CI, 0.8-5.6%). In conclusion, this study has suggested that physical activity and exposure to sunlight are important in the bone mineralization of prepubertal male and female children. The magnitude of both gender and environmental differences in bone mass in this age group is substantial, suggesting that modification at this stage of life may influence peak bone mass and possibly fracture risk in later life.

Body Composition↗
PubMed1998

The use of spectrophotometry to estimate melanin density in Caucasians.

The density of cutaneous melanin may be the property of the skin that protects it from damage by solar radiation, but there is not an accepted, noninvasive method of measuring it. To determine whether the density of cutaneous melanin can be estimated from reflectance of visible light by the skin, reflectance of 15-nm wavebands of light by the skin of the inner upper arm of each of 82 volunteers was measured at 20-nm intervals with a Minolta 508 spectrophotometer. A 3-mm skin biopsy was then taken from the same site, and four nonserial sections of it were stained with Masson Fontana for melanin. The melanin content of the basal area was calculated using the NIH Image analysis system. We show that cutaneous melanin in Caucasians can be estimated by the difference between two measurements of reflectance of visible light by the skin: those at wavelengths 400 and 420 nm. This new spectrophotometric measurement was more highly correlated (r = 0.68) with the histological measurements of cutaneous melanin than was skin reflectance of light of wavelength 680 nm (r = 0.33). Reflectances in the range of 650-700 nm have been used previously in skin cancer research. This relatively accurate measurement of melanin is quick and noninvasive and can be readily used in the field. It should provide improved discrimination of individual susceptibility to epidermal tumors in Caucasians and information about melanin's biological role in the causation of skin cancer.

Adult↗
PubMed1997

Differences in HDL cholesterol concentrations in Japanese, American, and Australian children.

BACKGROUND: Mortality from coronary heart disease is relatively low in Japan compared with other developed countries and has remained low despite an increasing standard of living and an apparent increase in mean plasma cholesterol concentration in adults over the past three decades. Important differences in childhood plasma lipoprotein profile might contribute to some of the difference in coronary heart disease mortality seen between Japan and both Australia and North America. METHODS AND RESULTS: Plasma HDL cholesterol and total cholesterol were surveyed in representative populations of schoolchildren in Australia, Japan, and Bogalusa, La. The mean concentration of plasma HDL cholesterol (but not total cholesterol) was higher for Japanese schoolchildren than for Australian or US schoolchildren (P<.001). In addition, the difference in plasma HDL cholesterol between the ages of 8 to 10 years and 12 to 15 years was much greater for Australian (boys, 15.2%; girls, 2.6%) and US (boys, 9.1%; girls, 2.7%) children than for their Japanese counterparts (boys, 4.2%; girls, 1.9%). An examination of potential explanatory factors revealed little difference in body mass index between samples, higher physical activity levels for the Japanese compared with the Australians, and substantial differences in dietary intake between Japanese and Australian schoolchildren. CONCLUSIONS: The relatively high ratio of plasma HDL cholesterol to total cholesterol in Japanese schoolchildren and the relatively small negative difference of plasma HDL cholesterol with age may help to explain why the coronary heart disease mortality rate in Japan is low compared with that in other developed countries.

Adolescent↗
PubMed1997

The Hobart Salt Study 1995: few meet national sodium intake target.

OBJECTIVE: To estimate 24-hour sodium and potassium excretion in an urban Australian population. DESIGN AND SETTING: Cross-sectional survey of an urban population in Hobart, Tasmania, in 1995. PARTICIPANTS: Systematic sample (87 men, 107 women) from the Commonwealth Electoral Roll of people aged 18-70 years on 30 June 1995 whose residential address was within 10 km of the Hobart General Post Office. MAIN OUTCOME MEASURE: Conformity with the national target for sodium intake for the year 2000 of < or = 100 mmol/day. RESULTS: The target was met by 6% of men and 36% of women. This difference between the sexes was significant (P < 0.001), while differences between age groups and socioeconomic levels were not significant. CONCLUSION: Our findings confirm the low level of conformity with the national sodium target reported by the handful of Australian studies over the past decade. Given the major community costs associated with hypertension, our results highlight the need for effective and properly monitored action to reduce sodium intakes.

Adolescent↗