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Biomedical subjects

S Morrell

Publications and source records attributed to S Morrell.

At least 19 recordsLinked to original sources
PubMed2002

Birth cohort effects in New South Wales suicide, 1865-1998.

OBJECTIVE: To examine birth cohort effects in New South Wales (NSW) suicide data (1865-1998). METHOD: Aggregate suicide data were examined after controlling for age and period using descriptive statistics and Poisson regression modelling. Three approaches were applied to address the non-identification of age, period and cohort in age-period-cohort (APC) models of suicide. RESULTS: Apparent cohort effects in male and female suicide using a minimum constraints APC model of age, period and cohort were no longer present in female suicide when a surrogate period APC model was used, and were absent in both male and female suicide when identifiable cohort effects were isolated using a 'drift' adjusted approach to APC modelling. CONCLUSION: Increases in youth suicide rates in NSW occurring since the 1960s cannot be attributed to cohort effects, such as family influences on development. The causes of youth suicide are thus effects operating contemporaneously.

Age Factors↗
PubMed2002

Suicide and political regime in New South Wales and Australia during the 20th century.

STUDY OBJECTIVE: Australia has had a two party parliamentary political system for most of the period since its Federation in 1901, dominated either by a social democratic (Labor) or a conservative ideological perspective. This paper investigates whether such political differences at Federal and State levels have influenced suicide rates in the state of New South Wales (NSW) for the period 1901-1998. DESIGN: Federal government type, NSW State government type, and combinations of both Federal and NSW State government type were examined. Poisson regression models were stratified by sex and controlled for the effects of age, annual change in gross domestic product, sedative availability, drought, and both world wars. RESULTS: When both Federal and NSW State governments were conservative the relative risk of suicide for NSW men was 1.17 (p<0.001) and for women 1.40 (p<0.001) compared with both governments being Labor (1.00). A statistically significant linear trend (p<0.001) in suicide risk was evident across the continuum of Federal/State government combinations, from both Labor (lowest), to mixed (intermediate), to both conservative (highest). CONCLUSION: Significantly higher suicide risk was associated with conservative government tenures compared with social democratic incumbents. Results are discussed in terms of the differences underpinning conservative and social democratic government programme ideology, and their relevance to Durkheim's theories of suicide, social regulation, and integration.

Adolescent↗
PubMed2002

Early cervical cancer rescreening.

INTRODUCTION: The extent of early cervical rescreening, defined as rescreening earlier than the recommended interval for a given initial test result, is difficult to determine mainly because the testing history of women is incomplete, especially with newer population based screening registers. METHODS: Estimation of early rescreening is based on analysis of a 1 month cohort of women (February 1997) recorded on the New South Wales Pap Test Register (PTR) who initially tested negative and who had no recorded history of a positive test result. For the purposes of estimating early rescreening rates and sources of multiple screening occurring within the recommended 2 yearly screening interval for New South Wales, the cohort excluded the estimated proportion of women with an unrecorded history of a positive result. Approaches to exclusion were different for women with a history of a high grade result (CIN2 or higher) or a low grade result (CIN1 or lower). RESULTS: Characteristic rescreening peaks occurred at 6, 12, 18, 24 and 27 months according to negative result category. The rescreening peak at 27 months illustrates the effect of the PTR late reminder system. After adjusting the cohort for estimated proportions of women with a history of a lesion, the number of women estimated to have rescreened early was approximately 156 000 over 1997-8, and the early rescreening rate was estimated as 15.3% of women who have a Pap test. A feasible target for reducing rescreening through service provider interventions was estimated to be a reduction of 7.4%, based on reducing the overscreening proportion from 15.3% to 7.9% through truncating characteristic rescreening peaks to background levels of rescreening. This represents just under 200 000 screens that could be performed over 2 years on New South Wales women who are underscreened or unscreened without incurring additional costs due to screening. CONCLUSIONS: Reasonable estimates of early cervical rescreening can be derived but some assumptions in estimating the proportion of women with a positive test result history may be needed particularly if a screening programme is new and universal recording of screening data is only recent. Characteristic peaks, as departures from a background of random noise in time plots of rescreening indicate that a component of early rescreening is systemic and the chief source of such variation in screening behaviour would be service providers.

Adult↗
PubMed2001

Cervical screening: population-based comparisons between self-reported survey and registry-derived Pap test rates.

OBJECTIVE: To compare self-reported cervical screening rates, as recorded in the 1998 NSW Health Survey, with registry-based cervical screening rates for NSW for the same period; and to examine factors associated with over-estimates of cervical screening rates by self-report. METHODS: Self-reported cervical screening data was extracted from the 1998 NSW Health Survey, biennial screening rates estimated and compared with biennial cervical screening rates for 1997-98, as recorded on the NSW Pap Test Register (PTR). Rates and differences were related to socio-demographic characteristics of the 17 Area Health Services of NSW. RESULTS: According to the 1998 NSW Health Survey, 74% of women reported having a Pap test during the previous two years. The equivalent rate recorded on the NSW PTR for 1997-98 was 62% (p<0.0001). Among the 17 Area Health Services of NSW these differences ranged from nine to 19 percentage points. Area-specific differences between self-reported and registry-based screening rates were negatively correlated with the registry-based screening rate. Age-specific differences between self-reported and registry-based screening rates were positively correlated with registry-based screening rates. No SES, regional or migrant population characteristics were predictive of differences between recorded and surveyed screening rates. CONCLUSION: Cervical screening rates in NSW derived from self-reported survey data exceed the rate recorded by the NSW Pap Test Register by 12 percentage points (equivalent to 19% inflation). IMPLICATIONS: The data in this paper can be used indicatively where necessary to adjust for over-reporting in cervical cancer screening surveys.

Adolescent↗
PubMed2001

Variation in cervical cancer screening by region, socio-economic, migrant and indigenous status in women in New South Wales.

The purpose of this study was to estimate the extent of association of cervical screening in NSW women with socio-economic status (SES), rurality, and proportions of non-English speaking background (NESB) and Indigenous status. Data on women who had at least one Pap test over two years (January 1998-December 1999) were obtained from the NSW Pap test Register. Each local government area (LGA) was allocated to categories of population proportions of NESB and Indigenous status, a rurality classification based on population density and remoteness, and to an SES quintile. The odds ratios (OR) of having a Pap test were estimated and confounding adjusted by multiple logistic regression analysis. Implied Pap test rates in urban NESB and in rural Indigenous women were estimated from the modelled estimates. The adjusted OR for a Pap test in large rural centres (1.14) was significantly higher than those for metropolitan or capital city residents (0.9 and 1.0 respectively). Adjusted OR for a Pap test in other rural centres (0.73) and other remote areas (0.64) were significantly lower than those for metropolitan or capital city residents. In urban populations the lowest OR were in areas with both low SES and high proportion of NESB. The lowest OR for Pap screening in rural populations occurred in the most remote areas with the highest proportion of Indigenous women. For urban NESB women the biennial Pap test rate was estimated as 50%, and for rural Indigenous women 29%, compared with the NSW average of 59%.

Adult↗
PubMed2001

General scales of community reaction to noise (dissatisfaction and perceived affectedness) are more reliable than scales of annoyance.

General measures of reaction to noise, which assess the respondent's perceived affectedness or dissatisfaction, appear to be more valid and internally consistent than more narrow measures, such as specific assessment of noise annoyance. However, the test-retest reliability of general and specific measures has yet to be compared. As a part of the large-scale Sydney Airport Health Study, 97 respondents participated in the same interview twice, several weeks apart. Test-retest reliabilities were found to be significant (p < 0.001) for two general questions and three specific "annoyance" questions. The general measures were significantly more valid for four of the six correlations (with activity disturbance), and more stable than the annoyance scales for five of the six possible test-retest comparisons. Amongst 1,015 respondents at Time 1, the questions regarding general reaction were more internally consistent than the questions regarding annoyance. Taken together, these data indicate that general measures of reaction to noise have superior psychometric properties (validity, internal consistency, and stability) compared with measures of specific reactions such as annoyance.

Adolescent↗
PubMed2000

Regulation of alcoholic fermentation in coleoptiles of two rice cultivars differing in tolerance to anoxia.

To investigate regulation of anaerobic carbohydrate catabolism in anoxia-tolerant plant tissue, rate of alcoholic fermentation and maximum catalytic activities of four key enzymes were assessed in coleoptiles of two rice cultivars that differ in tolerance to anoxia. The enzymes were ATP-dependent phosphofructokinase (PFK), pyrophosphate-dependent phosphofructokinase (PFP), pyruvate decarboxylase (PDC), and alcohol dehydrogenase (ADH). During anoxia, rates of coleoptile elongation and ethanol synthesis were faster in the more tolerant variety Calrose than in IR22. Calrose coleoptiles, in contrast to IR22, also showed a sustained Pasteur effect, with the estimated rate of glycolysis during anoxia being 1.4-1.7-fold faster than that of aerobic coleoptiles. In Calrose after 5 d anoxia, maximum catalytic activities of crude enzyme extracts were (in mumol substrate g-1 fresh weight min.-1) 170-240 for ADH, 4-6 for PDC and PFP and 0.4-0.7 for PFK. During anoxia, activity per coleoptile of all four enzymes increased 3-5.5-fold, suggesting that PFK, and PFP, like PDC and ADH, are synthesised in anoxic rice coleoptiles. Enzyme activities, on a fresh weight basis, were lower in IR22 than in Calrose. In vivo activities of PDC and PFK in anoxic coleoptiles from both cultivars were calculated using in vitro activities, estimated substrate levels, cytoplasmic pH, and S0.5 (the substrate level at which 0.5Vmax is reached, without inferring Michaelis-Menten kinetics). Data indicated that potential carbon flux through PFK, rather than through PDC, more closely approximated rates of alcoholic fermentation. That PFK is an important site of regulation was supported further for Calrose coleoptiles by a decrease in the concentration of its substrate pool (F-6-P + G-6-P) following the onset of anoxia. By contrast, in IR22, there was little evidence for control by PFK, consistent with recent evidence that suggests substrate supply limits alcoholic fermentation in this cultivar.

Alcohol Dehydrogenase↗
PubMed1999

Hepatitis A in Australia in the 1990s: future directions in surveillance and control.

The national notification data from 1952 to 1997 was examined in order to characterise hepatitis A virus (HAV) infection in Australia in the 1990s, and to determine whether currently available surveillance data are sufficient to inform disease control strategies and vaccination policies. Hepatitis A annual notification rates declined dramatically from a high of 123 notifications per 100,000 persons in 1961, to 3 per 100,000 in 1989. During 1991-97, the hepatitis A notification rate was 12 per 100,000 persons per year, although rates varied substantially between States and Territories. The Northern Territory had the highest notification rate of 52 per 100,000 persons per year. Seventy-six per cent of cases were adults, although in most regions notification rates were significantly higher in children than adults. Nationally, the male to female ratio was 1.7:1 (p < 0.001). The Northern Territory was the only area with no significant difference in notifications between the sexes. Large outbreaks were detectable through the notification system but risk factors for transmission could only be inferred from age and sex distribution of notifications, and from previous outbreak reports. National hepatitis A surveillance would be improved by collecting basic risk factor data, which identify cases as food-borne, sporadic, related to another case, or travel related. In addition, a population based serosurvey to measure age-specific hepatitis A susceptibility would assist vaccination policy development. Serosurveillance data are also needed, in conjunction with enhancements of the notification data, to provide baseline information against which the impact of changes in vaccination policy can be assessed.

Adolescent↗
PubMed1999

Urban and rural suicide differentials in migrants and the Australian-born, New South Wales, Australia 1985--1994.

We estimated risk of suicide in adults in New South Wales (NSW) by sex, country of birth and rural/urban residence, after adjusting for age; we also examined youth suicide (age 15-24 years). The study population was the entire population of NSW, Australia, aged > or =15 years during the period 1985-1994. Poisson regression was used to examine the relationship between predictor variables and the risk of suicide, with the focus on migrant status and area of residence. A significantly higher risk of suicide was found in male migrants from Northern Europe and Eastern Europe/former USSR, compared to Australian-born males; a significantly lower suicide risk occurred in males from Southern Europe, the Middle East and Asia. In female migrants, those from UK/Eire, Northern Europe, Eastern Europe/former USSR and New Zealand exhibited a significantly higher risk of suicide compared to Australian-born females. A significantly lower risk of suicide occurred in females from the Middle East. Male migrants overall were at significantly lower risk of suicide than the Australian-born, while female migrants overall had a significantly higher risk of suicide than Australian-born females. Among migrant males overall, the rural-urban suicide risk differential was significantly higher for those living in non-metropolitan areas (RR = 1.9; 95% CI: 1.7-2.1). Suicide risk was significantly higher in non-metropolitan male immigrants from the UK/Eire (RR = 1.4; 95% CI: 1.1-1.7), Southern Europe (RR = 1.7; 95% CI: 1.2-2.4), Northern/Western Europe (1.5; 95% CI: 1.2-1.9), the Middle East (RR = 3.8; 95% CI: 1.9-7.8), New Zealand (RR = 1.4; 95% CI: 1.0-1.8) and 'other' (RR = 2.6; 95% CI: 1.9-3.5), when compared to their urban counterparts. There was no statistically significant difference in suicide risk between rural and urban Australian-born males. For female suicide, significantly lower risk was found in female immigrants living in non-metropolitan areas who were from Northern/Western Europe (RR = 0.7; 95% CI: 0.4-0.96), as well as the Australian-born (RR = 0.7; 95% CI: 0.6-0.8), when compared to their urban counterparts. The non-metropolitan/metropolitan relative risk for suicide in female migrants overall was not significantly different from one. Among male youth there was a significantly higher suicide risk in non-metropolitan areas, with a relative risk estimate of 1.4 for Australian-born youth (95% CI: 1.2-1.5) and 1.7 for migrant youth (95% CI: 1.2-2.4), when compared with metropolitan counterparts. We conclude that suicide among migrant males living in non-metropolitan areas accounts for most of the excess of male suicide in rural NSW, and the significantly lower risk of suicide for non-metropolitan Australian-born women does not apply to migrant women.

Adolescent↗
PubMed1999

A case-control study of employment status and mortality in a cohort of Australian youth.

Recent studies have demonstrated a link in young populations between unemployment and ill health. The purpose of this study is to correlate mortality with employment status in two cohorts of young Australian males, aged 17-25 years, from 1984 to 1988. Two youth cohorts consisting of an initially unemployed sample (n = 1424 males) and a population sample (n = 4573 males), were surveyed annually throughout the study period. Those lost to follow-up during the survey period were matched with death registries across Australia. Employment status was determined from weekly diaries and death certificates and was designated as: employed or student; unemployed; not in the work force (excluding students). Conditional logistic regression, using age- and cohort- matched cases (deaths) and controls (alive), was used to estimate the odds ratio (OR) of dying with regard to employment status, taking into account potential confounders such as ethnicity, aboriginality, educational attainment, pre-existing health problems, socio-economic status of parents, and other factors. Twenty three male survey respondents were positively matched to death registry records. Compared to those employed or students (referent group), significantly elevated ORs were found to be associated with neither being in the workforce nor a student for all cause, external cause, and external cause mortality other than suicide. Odds ratios were adjusted for age, survey cohort, ethnicity, pre-existing physical and mental health status, education level, and socio-economic status of parent(s). A statistically significant increasing linear trend in odds ratios of male mortality for most cause groups was found across the employment categories, from those employed or student (lowest ORs), through those unemployed, to those not in the workforce (highest ORs). Suicide was higher, but not statistically significantly, in those unemployed or not in the workforce. Suicide also was associated, though not significantly, with the respondent not living with their parents when they were 14 years of age. No association was found between mortality and past unemployment experience, as measured by length of time spent unemployed, or the number of spells of unemployment experienced during the survey. The results of this study underscore the elevated risk to survival in young males as a consequence of being neither employed nor a student.

Adolescent↗
PubMed1998

Suicide in urban New South Wales, Australia 1985-1994: socio-economic and migrant interactions.

Variation of suicide with socio-economic status (SES) in urban NSW (Australia) during 1985-1994, by sex and country or region of birth, was examined using Poisson regression analysis of vital statistics and population data (age >¿ approximately 15 yr). Quintiles of SES were defined by municipality of residence and comparisons of suicide by SES were adjusted for age and country (or region) of birth (COB), and examined by COB. Risk of suicide in females was 28% that of males for all adults and 21% for youth (age 15-24 yr). Suicide risk was lower in males from southern Europe, Middle East and Asia, and higher in northern and eastern European males, compared to the Australian-born. Risks for suicide increased significantly with decreasing SES in males, but not in females. The relationship of male suicide and SES was stronger when controlled for COB. For males, the relative risk of suicide, adjusted for age and COB, was 66% higher in the lowest SES quintile compared to the highest quintile. and 39% higher for youth (age 15-24 yr). For male suicide, the population attributable fraction for SES (less than the highest quintile) was 27%. Analysis of SES differentials in male suicide according to COB indicated a significant inverse suicide gradient in relation to SES for the Australian-born and those born in New Zealand and the United Kingdom or Eire, but not in non-English speaking COB groups, except for Asia. For Australian-born males, suicide risk was 71% higher in the lowest SES group (compared to the highest), adjusted for age. These findings indicate that SES plays an important role in male suicide rates among the Australian-born and migrants from English-speaking countries and Asia, and among youth; but not in female suicide, nor suicide in most non-English speaking migrant groups. Reduction in SES differentials through economic and social policies may reduce male suicide in lower SES groups and should be seen to be at least as important as individual level interventions.

Adolescent↗
PubMed1998

Childhood incidence of acute lymphoblastic leukaemia and exposure to broadcast radiation in Sydney--a second look.

INTRODUCTION: Recent findings of an apparent association between incidence of childhood leukaemia and radio frequency radiation (RFR) from television transmission antennas in Sydney, NSW, are examined. METHODS: Incidence of childhood (0-14 years) acute lymphoblastic leukaemia (ALL) at the local government area (LGA) level is related to estimated exposure levels of RFR from television transmission antennas, using Poisson regression techniques. RESULTS: Most of the association between ALL incidence and television transmission RFR is shown to be the result of an influential observation: one of the highly exposed LGAs contributes all the excess, while in a similarly exposed LGA childhood ALL incidence was found to be no higher than the rate expected for NSW. With the influential observation excluded from the analysis, no positive correlation between exposure to RFR and leukaemia is evident. Conversely, under the assumption of an association with RFR, the low probability of the observed incident cases in LGAs under conditions of relatively high exposure to RFR conflicts with the assumption of an effect. CONCLUSION: The apparent association between childhood ALL incidence and RFR radiation from television towers is weaker when an LGA-level analysis is conducted.

Adolescent↗
PubMed1998

Best estimate of the magnitude of mortality due to occupational exposure to hazardous substances.

OBJECTIVES: With a proportionate attributable risk approach, to estimate the magnitude of premature mortality induced by exposure to hazardous substances in the Australian workforce. METHODS: Estimates of the magnitude of mortality induced by exposure to hazardous substances in the Australian work-force were calculated by the proportionate attributable risk approach after careful consideration of options for methodological refinements. The main data sources used were unit mortality datasets (individual deidentified death records), and tabulations when these were unavailable. RESULTS: The estimated number of deaths that occurred in Australia each year from occupational exposure to hazardous substances was 2290; 78% of these were men. The rate of mortality attributable to occupational exposure to hazardous substances was three to four times greater in male workers than in female workers. Male (productive) person-years of life lost (PYLL) were generally eight times higher than female PYLL. Cancer was the prime cause of death, followed by renal, cardiovascular, neurological, and chronic respiratory disease. Acute toxic episodes accounted for a small proportion of mortality but yielded a much larger proportion of PYLL, reflecting the relatively young ages of those who experienced fatal effects. CONCLUSIONS: Although national estimates of the proportions of mortality attributable to occupational exposure to hazardous substances seemed to be validly derived, uncertainties remain associated with the lack of an empirical basis for derivation of proportionate risk fractions used in the calculations. The finding of an appreciable burden of mortality that is attributable to past occupational exposure to hazardous substances emphasises the necessity for occupational health and safety authorities to measure and reduce worksite exposures. There is also an incentive to encourage the construction of appropriately designed cohort studies across industries and occupational groupings so that, ultimately, risk estimates may be directly calculated and applied to total workforce data for the definitive estimation of the magnitude of harm induced by occupational exposure to hazardous substances.

Australia↗
PubMed1997

A review of health effects of aircraft noise.

Social surveys have established dose-response relationships between aircraft noise and annoyance, with a number of psychological symptoms being positively related to annoyance. Evidence that exposure to aircraft noise is associated with higher psychiatric hospital admission rates is mixed. Some evidence exists of an association between aircraft noise exposure and use of psychotropic medications. People with a pre-existing psychological or psychiatric condition may be more susceptible to the effects or exposure to aircraft noise. Aircraft noise can produce effects on electroencephalogram sleep patterns and cause wakefulness and difficult in sleeping. Attendances at general practitioners, self-reported health problems and use of medications, have been associated with exposure to aircraft noise, but some findings are inconsistent. Some association between aircraft noise exposure and elevated mean blood pressure has been observed in cross-sectional studies of schoolchildren, but with little confirmation from cohort studies. There is no convincing evidence to suggest that all-cause or cause-specific mortality is increased by exposure to aircraft noise. There is no strong evidence that aircraft noise has significant perinatal effects. Using the World Health Organization definition of health, which includes positive mental and social wellbeing, aircraft noise is responsible for considerable ill-health. However, population-based studies have not found strong evidence that people living near or under aircraft flight paths suffer higher rates of clinical morbidity or mortality as a consequence of exposure to aircraft noise. A dearth of high quality studies in this area precludes drawing substantive conclusions.

Aircraft↗
PubMed1995

Cytochrome P450 catalyzed covalent binding of methoxychlor to rat hepatic, microsomal iodothyronine 5'-monodeiodinase, type I: does exposure to methoxychlor disrupt thyroid hormone metabolism?

The insecticide methoxychlor is estrogenic in birds and mammals and interferes with sexual development and reproduction, but it is not known whether this toxicity is due solely to its estrogenicity. We now have found that during hepatic, microsomal metabolism of [ring-14C]- or [3H-OCH3]methoxychlor, their metabolite primarily binds to iodothyronine 5'-monodeiodinase, type I (5'-ID1). The purified, radiolabeled protein reacted with antibodies against protein disulfide isomerase, isoform Q5, which is highly homologous to 5'-ID1. Sequencing of the radiolabeled tryptic peptide indicated that methoxychlor bound to cysteine 372 or 375 or to lysine 376 of 5'-ID1. Treatment of rats with methoxychlor for 4 days decreased hepatic, microsomal 5'-ID1 activity from 2.94 to 2.20 nmol/min-mg prot (P < 0.02). Since 5'-ID1 catalyzes thyroxine conversion to the biologically active triiodothyronine, these data suggest that methoxychlor may interfere with thyroid hormone metabolism. This may be an additional factor in its environmental toxicity.

Amino Acid Sequence↗