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Biomedical subjects

D Christie

Publications and source records attributed to D Christie.

At least 19 recordsLinked to original sources
PubMed1992

Air quality and respiratory disease in Newcastle, New South Wales.

OBJECTIVE: To investigate respiratory illnesses in the Newcastle region, their change over time, and their geographic relationship to industrialised areas. DESIGN: We analysed admissions to public hospitals by postcode area in the Newcastle region, for all causes and for all the various respiratory causes, for the years 1979-1988. Comparisons were made between the State of New South Wales and the Newcastle area, and between geographic areas within Newcastle. Changes over the 10-year period were noted. RESULTS: For both all causes and respiratory causes, admission rates to Newcastle hospitals, 1979-1988, were significantly lower than those for the rest of New South Wales in 1986. There was a correlation between living in the industrial part of the city and hospital admission for all causes and respiratory causes. There was also a correlation between mean disposable family income and hospital admissions, with those areas with the higher incomes having lower admission rates. Over the 10 years studied there was a statistically significant decline in admissions for respiratory causes, both in absolute terms and after controlling for changes in admissions for all causes. In children aged 0-14 years a significant increase in admissions for asthma occurred between 1979 and 1988, which could not be explained by diagnostic shift. CONCLUSIONS: On the basis of hospital statistics, the members of the Newcastle population seem little different from those in the remainder of New South Wales. From 1979-1988, the efforts by industry, with the support of the community, to reduce industrial pollution have been accompanied by a reduction in hospital admission rates for respiratory diseases in general and for chronic obstructive lung disease in older people. Other contributing factors include reduced smoking rates and improved medical management. Correlations between geographic location and respiratory admission rates may be a manifestation of social class rather than poor air quality, although a contribution from the latter cannot be discounted. A concomitant rise in asthma admission rates in children aged 0-14 is likely to be unrelated to any change in air quality.

Adolescent↗
PubMed1992

Localization of the platelet-specific HPA-2 (Ko) alloantigens on the N-terminal globular fragment of platelet glycoprotein Ib alpha.

The human platelet-specific alloantigens HPA-2a and HPA-2b (= Kob and Koa) together constitute a biallelic antigen system. The HPA-2 antigens have not, to date, been located on a particular platelet membrane molecule. Here, we describe the localization of these antigens on platelet glycoprotein (GP) Ib alpha. Platelets from two patients with the Bernard-Soulier syndrome (BSS) were HPA-2(a-,b-) in the immunofluorescence test with HPA-2 alloantibodies on chloroquine-treated platelets. With monoclonal antibody (MoAb) immobilization of platelet antigen assay (MAIPA), positive reactions were obtained only when MoAbs against the platelet GPIb/IX complex were used in combination with anti-HPA-2a or -2b alloantibodies and normal donor platelets. By immunoprecipitation under nonreducing and reducing conditions a protein of 160 Kd and 145 Kd, respectively, was precipitated by the anti-HPA-2a serum. A protein migrating identically to this was precipitated by anti-GPIb MoAb. Normal donor platelets became HPA-2(a-,b-) after elastase treatment, suggesting that anti-HPA-2 antibodies bind to the N-terminal elastase-sensitive part of GPIb alpha. Anti-HPA-2a antibodies inhibited the ristocetin-induced agglutination of HPA-2a-positive platelets but not of HPA-2a-negative platelets, indicating that the epitopes recognized by these alloantibodies are localized in the proximity of the von Willebrand-factor-binding domain. Together, these data provide evidence that the HPA-2 alloantigens are located on the N-terminal globular elastase-sensitive part of GPIb alpha. Furthermore, we show that the recently described Siba antigen is probably identical to HPA-2a.

Antibodies, Monoclonal↗
PubMed1992

Measles immunisation compliance: poor impact of bicentennial measles control campaigns on children under five.

A measles immunisation survey was conducted among children who enrolled in school kindergarten classes in the Eastern Sydney Area in 1989. Its aims were to determine baseline compliance rates, to identify subpopulations at risk of poor compliance and to evaluate the impact of the bicentennial measles control campaigns on compliance among children under five years. All 73 schools participated, questionnaires were returned by 2230 (81.4%) children, and compliance with immunisation was 91.3%. 89.1% of children attending public schools were immunised, compared to 91.9% of Catholic school pupils and 95.8% of independent school pupils (chi 2 = 21.4, P less than 0.001). Among public school children, 91.6% of pupils from English-speaking families were immunised in comparison to 81.4% of pupils from non-English-speaking backgrounds (chi 2 = 20.5, P less than or equal to 0.001). The fraction of previously unimmunised children who were known to have been immunised during each year of the measles control campaigns was 16% in 1986-87, 10% in 1987-88 and 9% in 1988-89. These small increments in immunisation uptake suggest that under-five-year-olds were not effectively targeted by the measles control campaigns. However, no control group was evaluated. Immunisation delivery systems must be designed which ensure that all children receive measles-mumps-rubella vaccine as soon as possible after the first birthday. Immunisation promotions and service providers will need to target specific language and socioeconomic groups.

Australia↗
PubMed1991

A prospective study in the Australian petroleum industry. I. Mortality.

This paper reports the mortality experience of employees of the Australian petroleum industry from 1981 to 1989. Two surveys by personal interview incorporated more than 15,000 employees representing 92% of the eligible population. Subjects were included in the analysis after completing five years of service in the industry. At the time of this report the cohort does not include sufficiently large numbers of women for useful analysis; results presented are restricted to men. By 31 December 1989, 76,529 person-years of observation had accumulated for male mortality with 241 deaths. The standardised mortality ratio (SMR) analysis showed a favourable mortality experience for most causes with overall cancer rates slightly lower than those of the national population. Whereas deficits were seen in some cancer sites, notably lung cancers (SMR 0.5, 95% confidence interval (95% CI) 0.3-0.8), mortality for lymphohaematopoietic cancers, notably leukaemia (SMR 1.6, 95% CI 0.6-3.4) suggested increased risk. The SMR for cancers of the pleura was 3.9 (95% CI 0.8-11). Two of the three cases seen had previous employment, however, in industries with likely exposure to asbestos.

Australia↗
PubMed1991

A prospective study in the Australian petroleum industry. II. Incidence of cancer.

This paper reports incidence of cancer in employees of the Australian petroleum industry from 1981 to 1989. Two surveys by personal interview incorporated more than 15,000 employees, representing 92% of the eligible population. Subjects were included in the analysis after completing five years of service in the industry. At the time of this report the cohort did not include sufficiently large numbers of women for useful analysis; results presented are restricted to the men. On 31 December 1989, 50,254 person-years of observation had accumulated in the men with 152 incident cancers reported. The standardised incidence ratio (SIR) analysis showed overall cancer rates close to those of the national population. Whereas deficits were seen in some cancer sites, notably lung cancer (SIR 0.5, 95% confidence internal (95% CI) 0.3-0.9), incidence rates for some other cancer sites suggested increased risk. An excess of observed over expected cases was present in all subcategories of lymphohaematopoietic cancer except Hodgkin's disease (no cases), and was most apparent in myeloid leukaemia (SIR 4.0, 95% CI 1.6-8.2). The other major site with a raised number of cases observed over expected was melanoma (SIR 1.4, 95% CI 0.8-2.1).

Australia↗
PubMed1990

The effect of unilateral anteromedial cortex lesions on prey-catching and spatio-motor behaviour in the rat.

The neglect which follows a unilateral lesion of anteromedial cortex in rat was examined using two tasks. In the first task animals had to press the left bar of a two-bar Skinner box for food reward. In the second task animals captured live locusts presented in either their right or left visual field. The results showed that in the Skinner box there was a transitory spatial neglect contralateral to the lesion, which disappeared after 2-3 days. In the prey-catching task animals failed to target or track locusts when they were in the field contralateral to the lesion throughout the 4-day testing period. Capture and consummatory responses were normal when the locust was presented (or moved independently) into the ipsilateral (non-neglected) field. 60 days later the asymmetrical response to locusts in the contralateral field had disappeared.

Animals↗
PubMed1990

Corpus callosum section disrupts motor behaviour strategies during visual discrimination learning in rat.

Monocularly patched rats were trained on a series of visual tilt discriminations ordered from simple to difficult to measure the angular difference threshold of each eye. The stereotyped running pattern which the animal made was also recorded. Callosal section disrupted a preoperatively established running pattern and produced an ocular neglect; the animal's performance dropped to chance when it used the eye ipsilateral to the preferred side of approach.

Animals↗
PubMed1990

Molecular portrait of lens gap junction protein MP70.

A 70-kDa membrane protein (MP70) is a component of the lens fiber gap junctions. Its membrane topology and its N-terminal sequence are similar to those of the connexin family of proteins. Some features of MP70 containing fiber gap junctions are, however, distinct from gap junctions in other mammalian tissues: (i) Lens connexons form crystalline arrays only after cleavage of junctional proteins in vitro. These hexagonal arrays have a periodicity of 13.6 nm which is significantly larger than the 8- 9-nm spacing of liver and heart gap junctions. (ii) Lens fiber gap junctions dissociate in low concentrations of nonionic detergent and this provides an avenue to purify MP70 directly from a membrane mixture. Isolated MP70 in the form of 17 S structures has an appearance consistent with connexon pairs. (iii) The C-terminal half of MP70 is cleaved in situ by a lens endogenous calcium-dependent protease. The processed from MP38 remains in the membrane and is abundant in the central region of the lens. A testable hypothesis for MP70 function is presented.

Connexins↗
PubMed1990

Changes in instrumentally and classically conditioned limb-flexion responses following inferior olivary lesions and olivocerebellar tractotomy in the cat.

Lesions were placed in various parts of the inferior olivary nucleus and olivocerebellar tract in an attempt to define further the role of the inferior olive in the performance of a conditioned limb-flexion response (LFR) in cats. Thirty-two cats were trained to make an LFR using either classical or instrumental conditioning. The conditioned stimulus (CS) was a tone, and the unconditioned stimulus (US), a shock to the forelimb. Following training, lesions were placed in various parts of the inferior olivary nucleus in 20 animals (radio frequency lesions, 17; electrolytic lesions, 3). Midline section of the olivocerebellar tract was carried out in 12 animals. The degree of conditioned-response (CR) loss resulting from a given lesion was closely related to the precise locus of the lesion. Rostromedial olivary lesions, which included the spino- and cortico-olivary forelimb projection zones and the olivocerebellar projection area, resulted in varying degrees of CR loss (from partial to near total), deregulation of response latency, and a significant reduction of response amplitude. The CR deficit and degree of post-operative CR recovery were directly related to the extent of damage to this part of the rostromedial olive. Lesions restricted to the caudal olive or to caudal levels of the olivo-cerebellar tract resulted in no postoperative CR deficits. Animals with caudal lesions, however, showed more severe general motor deficits postoperatively than did those with rostromedial lesions and loss of the CR. Prolonged training of animals with the most complete CR deficits resulted in some relearning, but response patterns were typified by long-latency, low-amplitude CRs and a highly unstable response pattern.

Animals↗
PubMed1989

The effects of anteromedial cortex lesions on pattern discrimination learning in rat.

The visual angular difference threshold of rats with unilateral anteromedial cortex lesions was measured. The stereotyped running pattern and preoperatively preferred side of approach in a two-choice visual discrimination apparatus was recorded for each animal. Lesions in the hemisphere ipsilateral to the preferred approach side did not affect either the running pattern or the angular difference threshold. However, there was a general reduction in the detection of the positive stimulus throughout the scale. Lesions in the contralateral hemisphere produced a transient reversal of the side preference with an overall loss of S + detection in the field contralateral to the side approached.

Animals↗
PubMed1989

Monocular pattern discrimination learning after unilateral lesions of anteromedial cortex in rat.

Monocularly patched rats were trained on a series of visual tilt discriminations ordered from simple to difficult to measure the angular difference threshold of each eye. Preoperatively there was no difference between discrimination performance for either eye. Unilateral lesions of anteromedial cortex did not alter the monocular angular difference threshold. However, there was a reduction in discrimination performance for all angular difference comparisons. Animals showed a visual neglect for stimuli in the field contralateral to the lesion. The neglect was independent of the eye used for the discrimination.

Animals↗
PubMed1989

Social class as indicated by area of residence: a mortality study within an Australian industrial population.

The influence of social class on morbidity and mortality is well known and, in many epidemiological settings, its role as a potential confounding variable must be addressed. In occupational studies, particularly those based within a single industry, it is difficult to measure social class by scales based on occupational prestige. In a population study within the Australian petroleum industry, the all-cause mortality of males has been examined by social class, as indicated by area of residence, specifically, postcode. Rates of mortality were higher in the lower social classes, and the gradient was similar to that observed previously. The mortality rate of the lowest social class group relative to the highest was 1.73, and the test for trend was significant (p = 0.003). Whilst adjustment for smoking reduced the gradient somewhat, a social class effect remained.

Adult↗
PubMed1989

Distribution of MP17 in isolated lens fibre membranes.

MP17 is the second most abundant integral membrane protein in the mammalian lens. It has some common features with the major intrinsic polypeptide MIP26, but amino terminal sequencing shows that MP17 is a separate gene product. Both MP17 and MIP26 are abundant in isolated lens fibre membrane vesicles and are not detectable in the fibre gap junctions.

Amino Acid Sequence↗
PubMed1988

Homologies between gap junction proteins in lens, heart and liver.

The cells in the mammalian lens are electrically and metabolically coupled with each other by a network of gap junctions. These are clusters of transmembrane channels by which the fibre cells situated deeper in the lens communicate through the epithelium with the aqueous humour, the source of nutrients for the lens. Hence gap junctions are important for lens transparency. The gap junction proteins in the mammalian lens have not yet been identified with certainty. A putative fibre gap junction protein of relative molecular mass 26,000 (26K) is not related to those from other tissues, such as the liver 28K junction component. Another lens membrane protein with Mr 70K (MP70) has also been localized in the lens fibre gap junctions. Here we demonstrate by amino-terminal sequence analysis that MP70 and its in vivo-processed form, MP38 (ref. 8), belong to a wider family of gap junction proteins. With this new data on the lens, homologies between gap junction proteins now extend to organs derived from all three embryonal layers, endoderm (liver), mesoderm (heart) and ectoderm (lens).

Amino Acid Sequence↗
PubMed1988

Patient and spouse responses to education early after myocardial infarction.

The impact of a post myocardial infarction education programme was assessed by comparing the increase in knowledge of patients and spouses about CHD in two hospitals, one (A) with and the other (B) without such a programme. Subjects completed the same two questionnaires twice, once within 4 days of admission and again within 16 days of leaving hospital. Q1 contained 83 questions about CHD and Q2, consisted of seven questions of immediate practical relevance to their convalescence. When the two hospitals were compared the only significant changes were observed in the responses of spouses and patients from hospital A. Spouses in A increased their scores on Q1 by a mean of 7.13% (p 0.001) in contrast to a fall of 2.01% in B. The mean increase in scores on Q2 for patients in A was 19.3% (p 0.001). It is concluded that an education programme increases the knowledge of patients and spouses but that their learning ability differs. Whilst it is suggested that spouses are included in patient education it appears likely that their educational needs may differ from those of the patient.

Adult↗
PubMed1987

Recidivism in a cohort of young Australian drinking-drivers.

Four hundred and sixty-three men aged 18-25 years were referred to a counselling programme in 1975-1977, after their first conviction for an alcohol-related traffic offence. Records of the Victoria Police, and those of the Motor Registration Board, were searched for subsequent alcohol-related traffic offences up to February 1984. Those subjects who had left the State of Victoria or had died were identified, and a "survival" curve was constructed where survival implied freedom from reconviction for an alcohol-related traffic offence. By means of Cox's proportional hazards model, the rate ratios of a number of predictor variables of recidivism were calculated; those of significance were the number of drinks per week, social class, and a history of "family troubles with drinking". Reduction of alcohol consumption may be a more appropriate goal in programmes that are concerned with the counselling of young drinking-drivers than is attempted modification of the drinking-driving nexus.

Accidents, Traffic↗