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Biomedical subjects

R Jackson

Publications and source records attributed to R Jackson.

At least 37 records · Page 2Linked to original sources
PubMed1995

Trends in coronary heart disease risk factors in Auckland 1982-94.

AIMS: This paper describes trends in major coronary heart disease risk factors over the period 1982 to 1994 in the city of Auckland, New Zealand. METHODS: Coronary heart disease risk factor levels were measured in three cross-sectional surveys in Auckland in 1982, 1986-8 and 1993-4, following a standardised protocol. Random samples of nonMaori, nonPacific Island adults aged 35-64 years were selected from the Auckland general electoral rolls using similar methods in all three surveys. Participants attended a study centre for interview and risk factor measurement. RESULTS: The analyses presented are based on samples of 1029 men and 569 women in 1982, 541 men and 365 women in 1986-8, and 712 men and 685 women in 1993-4. The data are directly age-standardised to the 1986 New Zealand population. Over the 12 year period the prevalence of self-reported cigarette consumption declined significantly from 28.6% to 16.9% in men and from 24.5% to 14.8% in women. Mean serum total cholesterol showed little change between 1982 and 1986-8 but declined significantly between 1986-8 and 1993-4 by approximately 6% from 6.12 mmol/L to 5.73 mmol/L in men and by 9% from 6.17 mmol/L to 5.60 mmol/L in women. Mean serum high density lipoprotein (HDL) cholesterol showed a modest increase between 1982 and 1986-8 but declined significantly between 1986-8 and 1993-4 by 12% from 1.25 mmol/L to 1.10 mmol/L in men and by 9% from 1.55 mmol/L in women to 1.40 mmol/L in women. The total cholesterol to HDL cholesterol ratio increased significantly between 1986-8 and 1993-4 by 6% in men but showed little change in women. Mean blood pressure levels fell by 4-6 mmHg systolic and 6-7 mmHg diastolic over the 12 year period in men and women. Mean body mass index increased significantly from 25.6 to 26.4 in men and from 24.5 to 25.1 in women during this period. CONCLUSIONS: Over the 12 year period, 1982-94 there have been substantial reductions in the prevalence of self reported cigarette smoking, mean serum total cholesterol levels and mean blood pressure levels in middle aged Aucklanders. Of concern, the prevalence of obesity has increased and mean serum HDL cholesterol levels have fallen over the period. Coronary heart disease prevention and control programmes appear to have been successful in reducing the prevalence of most major coronary heart disease risk factors however some reorientation will be required to redress the adverse trends in HDL cholesterol levels and obesity.

Adult↗
PubMed1995

Association of angiotensinogen gene T235 variant with increased risk of coronary heart disease.

Several genes, including some encoding components of the renin angiotensin system, are associated with the risk of cardiovascular diseases. There have been reports linking a homozygous deletion allele of the angiotensin converting enzyme (ACE) gene (DD) with an increased risk of myocardial infarction, and some variants of the angiotensinogen gene with an increased risk of hypertension. In a case-control study of a caucasian population from New Zealand, we examined the associations with coronary heart disease (CHD) of ACE DD and of a mis-sense mutation with methionine to threonine aminoacid substitution at codon 235 in the angiotensinogen gene (T235). We studied 422 patients (mean age 62 years, 81% male) with documented CHD (50% with myocardial infarction) and 406 controls without known CHD (frequency-matched to cases by age and sex). Risk factors for CHD were assessed by standard questionnaire, physical examination, and blood tests. Genomic DNA from leucocytes was analysed for various ACE and angiotensinogen alleles. Angiotensinogen T235 homozygotes were at significantly increased risk of CHD generally (odds ratio 1.7, 2 p = 0.008) and of myocardial infarction specifically (1.8, 2 p = 0.009). Adjustment for several risk factors increased the estimate of CHD risk associated with this allele to 2.6 (2 p < 0.001) and the estimate for myocardial infarction risk to 3.4 (2 p < 0.001). By contrast, there was no evidence of a significant increase in the risk of CHD or myocardial infarction among individuals with ACE DD. We conclude that the T235 polymorphism of the angiotensinogen gene is an independent risk factor, which carries an approximately two-fold increased risk of CHD. In this study, however, ACE DD was not associated with any detectable increase in CHD risk.

Alleles↗
PubMed1995

Dual-acting thromboxane receptor antagonist/synthase inhibitors: synthesis and biological properties of [2-substituted-4-(3-pyridyl)-1,3-dioxan-5-yl] alkenoic acids.

The design, synthesis, and pharmacology of a new class of compounds possessing both thromboxane receptor antagonist and thromboxane synthase inhibitory properties are described. Replacement of the phenol group of the known thromboxane antagonist series 4(Z)-6-[(4RS,5SR)-4-(2-hydroxyphenyl)-1,3-dioxan-5-yl] hex-4-enoic acid by a 3-pyridyl group led to a series of compounds, 5, which were potent thromboxane synthase inhibitors and weak thromboxane antagonists. Further modifications at the dioxane C2 position led to compounds, 7, which were potent dual-acting agents. In the case of compound 7w, the dual activity was shown to reside almost exclusively in the (-)-enantiomer, 7x. Following oral dosing to rats and dogs, 7x (3 mg/kg) displayed significant dual activity over a period of at least 8 h.

Animals↗
PubMed1995

Effect of environmental factors on risk of injury of child pedestrians by motor vehicles: a case-control study.

OBJECTIVE: To identify and assess contribution of environmental risk factors for injury of child pedestrians by motor vehicles. DESIGN: Community based case-control study. Environmental characteristics of sites of child pedestrian injury were compared with the environmental characteristics of selected comparison sites. Each comparison site was the same distance and direction from home of control child as was the injury site from home or relevant case child. Two control sites were selected for each injury site. SETTING: Auckland region of New Zealand. SUBJECTS: Cases were 190 child pedestrians aged < 15 who were killed or hospitalised after collision with a motor vehicle on a public road during two years and two months. Controls were 380 children randomly sampled from population and frequency matched for age and sex. MAIN OUTCOME MEASURE: Traffic volume and speed and level of parking on curbs at injury sites and comparison sites. RESULTS: Risk of injury of child pedestrians was strongly associated with traffic volume: risk of injury at sites with highest traffic volumes was 14 times greater than that at least busy sites (odds ratio 14.30; 95% confidence interval 6.98 to 29.20), and risk increased with increasing traffic volume. High density of curb parking was also associated with increased risk (odds ratio 8.12; 3.32 to 19.90). Risk was increased at sites with mean speeds over 40 km/h (odds ratio 2.68; 1.26 to 5.69), although risk did not increase further with increasing speed. CONCLUSION: Reducing traffic volume in urban areas could significantly reduce rates of child pedestrian injury. Restricting curb parking may also be effective.

Accidents, Traffic↗
PubMed1995

End of the New Zealand asthma mortality epidemic.

In 1989, a case-control study reported that inhaled fenoterol was associated with the epidemic of asthma deaths that had affected New Zealand since 1976. The New Zealand Department of Health issued warnings about the safety of fenoterol and restricted its availability. The associated time trends are consistent with the hypothesis that fenoterol was the main factor in the New Zealand asthma mortality epidemic. The epidemic commenced when fenoterol was introduced in 1976, and the New Zealand death rate remained the highest in the world for more than a decade. After publication of the case-control study, the death rate fell by half and has now remained low for a further 3 years (1990-92). Time-trend data do not suggest a class effect of inhaled beta-agonists in the epidemic: there was no association between beta-agonist sales and the start of the epidemic, and total sales of inhaled beta-agonists actually increased slightly during 1989-90 when the epidemic came to an end. Time-trend data are also inconsistent with the hypothesis that the epidemic may have occurred because of underprescribing of inhaled corticosteroids. Similarly, time-trend data is incosistent with hypotheses postulating a major role of social factors such as unemployment. Data on time trends should be assessed with caution, because time trends in asthma deaths can be affected by many factors. Nevertheless, the New Zealand time trends are consistent with fenoterol being the main cause of the New Zealand asthma mortality epidemic and are inconsistent with a significant role for other suggested causes.

Administration, Inhalation↗
PubMed1995

Polymerase chain reaction for rapid detection of ocular adenovirus infection.

Adenoviruses are associated with endemic and epidemic acute conjunctivitis, large nosocomial outbreaks reflecting virus transmission on unwashed hands or inadequately sterilised ophthalmic instruments. The polymerase chain reaction (PCR) proved more sensitive than antigen detection by immune dot-blot test for the rapid diagnosis of ocular adenovirus infection (sensitivities in a retrospective study 112/123 (91%) versus 72/123 (59%), P < 0.001). Indeed, in a prospective comparison, DNA amplification and virus isolation generated similar numbers of positive results (34 versus 32), though five PCR positive results were possibly false positives. The sensitivity of the PCR was largely independent of adenovirus subgenus or serotype, though reduced sensitivity with subgenus B strains could not be excluded. Specimen preparation for DNA amplification using a simple lysis buffer proved more effective than phenol-chloroform extraction. The immune dot-blot test gave unavoidable false positive results, but with the PCR this problem could be minimized by technical modifications. The PCR could replace antigen detection and virus isolation as the initial test for adenoviruses in conjunctival swabs, with cell culture only being retained for adenovirus serotyping in PCR positive specimens and for other viruses such as herpes simplex.

Adenoviridae↗
PubMed1995

Potent inhibition of human immunodeficiency virus by MDL 101028, a novel sulphonic acid polymer.

MDL 101028, a novel biphenyl disulphonic acid urea co-polymer was designed and synthesised as a heparin mimetic. This low molecular weight polymer showed potent inhibition of human immunodeficiency virus type 1 (HIV-1) replication in a number of host-cell/virus systems, including primary clinical isolates of the virus cultured in human peripheral blood mononuclear cells (PBMCs). When compared with the heterogeneous polysulphated molecules, heparin and dextran sulphate, this chemically defined compound showed equivalent antiviral activity with 50% inhibitory concentrations (IC50s) in the range 0.27-3.0 micrograms/ml in the host-cell/virus systems tested. MDL 101028 also inhibited the replication of HIV type 2 and the simian immunodeficiency virus (SIV), as well as HIV-1 variants resistant to reverse transcriptase inhibitors. Virus growth was blocked when exposure of T-lymphocytes to MDL 101028 was restricted to the virus absorption stage, or even in whole blood conditions. MDL 101028 did not irreversibly inactivate virions, and in contrast to heparin, did not inhibit the attachment of radiolabelled HIV-1 to CD4+ T-cells. MDL 101028 blocked HIV-induced cell-to-cell fusion and this activity appears to explain the mechanism of its antiviral action. The antiviral evaluation of discrete oligomer molecules of MDL 101028 showed that a polymer chain length of six repeating units had optimal potency. The lack of anticoagulant properties and significant antiviral activity in whole blood may allow the development of MDL 101028 as a treatment of HIV infections.

Animals↗
PubMed1995

Volume preloading is not essential to prevent spinal-induced hypotension at caesarean section.

We have compared the protective effect of 1000 ml preload with 200 ml preload of crystalloid solution, administered during the 10 min before spinal anaesthesia was induced, in 60 healthy women with no fetal compromise undergoing elective Caesarean section. The spinal anaesthetic was managed identically in both groups by an anaesthetist who was unaware of the volume of fluid administered. A prophylactic infusion of ephedrine 60 mg in Hartmann's solution 500 ml was given according to maternal arterial pressure. Hypotension was defined as > or = 30% reduction from baseline or < 90 mm Hg, and was treated by i.v. ephedrine bolus doses. There was no significant difference in ephedrine requirements between the two groups or in the incidence, severity or duration of hypotension: 10 women in the 1000-ml group, five episodes lasting > or = 3 min compared with nine women in the 200-ml group, four lasting > or = 3 min. There was no difference between neonates in each group. We have now abandoned the routine of preloading before regional anaesthesia.

Adult↗
PubMed1995

Do cardiovascular disease risk factors predict all-cause mortality?

BACKGROUND: The purpose of this study is to describe associations between a number of standard cardiovascular risk factors and all-cause mortality. METHOD: Mortality data were collected for a randomly selected cohort of 1029 New Zealand men aged 35-64 years, followed up over a 9-year period. A proportional hazards regression model was used to estimate the relative risks (RR) for all-cause mortality associated with a number of cardiovascular risk factors. RESULTS: In all, 96 deaths occurred over the 9-year period, of which 50% were due to cardiovascular causes. All-cause mortality was positively associated with cigarette smoking (age-adjusted RR = 2.01, 95% CI:1.15-3.53, current versus never), systolic blood pressure (age-adjusted RR = 2.18, 95% CI:1.23-4.44, upper versus lower tertile), and body mass index (age-adjusted RR = 1.59, 95% CI:0.94-2.66, upper versus lower tertile) and inversely associated with high density lipoprotein (HDL)-cholesterol (age-adjusted RR = 0.45, 95% CI:0.25-0.80, upper versus lower tertile). All-cause mortality was only weakly associated with serum total cholesterol (age-adjusted RR = 1.19, 95% CI:0.70-1.99, upper versus lower tertile), and there was no evidence of a U-shaped relationship for this risk factor. There was an inverse association between all-cause mortality and socioeconomic status (age-adjusted RR = 1.70, 95% CI:1.03-2.80, lower versus upper). Light alcohol consumption was associated with reduced all-cause mortality (age-adjusted RR = 0.63, 95% CI:0.37-1.05, light versus teetotal), but this benefit did not persist for alcohol consumption above about three standard drinks per day. CONCLUSIONS: The findings of this study indicate that the standard cardiovascular risk factors are likely to have a beneficial impact on all-cause mortality as well as cardiovascular disease in middle-aged and older men.

Adult↗
PubMed1995

Use and safety of acellular pertussis vaccine among adult hospital staff during an outbreak of pertussis.

During May and June 1993, 10 patients and 5 members of the clinical staff at a hospital in California were diagnosed with Bordetella pertussis infection. In addition to erythromycin prophylaxis, 630 (48%) of 1330 staff members received a half dose of acellular pertussis vaccine with tetanus and diphtheria toxoids (DTaP). To identify side effects of the vaccine, a questionnaire was completed by 344 (54%) of 630 vaccinated staff. Side effects were reported by 117 respondents (34%); 64 were classified as mild (local reaction at injection site) and 50 as moderate (systemic complaints or local reaction resulting in limitation of arm movement). Three vaccinees (< 1%) reported missing 1 or more days of work because of their symptoms. Local reactions at the injection site occurred in 100 (29%), systemic symptoms in 38 (11%), and limitation of arm movement in 18 (5%). This study indicates that use of half dose of DTaP in adults appears safe and should be considered as an adjunct to chemoprophylaxis during institutional outbreaks.

Adult↗
PubMed1995

What are the implications for the community of the discrepancy between the theory and practice of BP control?

Epidemiological data suggest that the lower the BP, the lower the cardiovascular risk. This is true across a broad range of BP levels, including those considered 'normal'; more than half of all cardiovascular events attributed to raised BP occur when DBP is < or = 95 mmHg. The belief that lowering BP too far is harmful is based on the hypothesis of a J-shaped relationship between BP and risk of cardiovascular disease. The weight of evidence now clearly suggests, however, that the J-shaped curve is not a consequence of treatment, but of underlying cardiovascular dysfunction that reduces BP and increases morbidity and mortality. Current prospective observational data give no evidence of a threshold BP below which there is no further reduction in cardiovascular disease risk. The average BP reductions in randomised trials are 5-6 mmHg (diastolic) and 10-12 mmHg (systolic), which would be expected to reduce the incidence of stroke by 35% and of coronary heart disease by 21%. If average BP reductions were doubled, prospective observational studies suggest the cardiovascular risk would be reduced by a further 15-20%.

Antihypertensive Agents↗
PubMed1995

The composition of Roman medical instrumentaria as an indicator of medical practice: a provisional assessment.

Archaeological evidence, in the form of sets of instruments and doctors' tombstones, can provide pointers towards the varied roles of Greco-Roman medical personnel. A number of recent discoveries have prompted a consideration of the range of instruments in those instrumentaria which are believed to be complete. The variety of instruments, and the presence, absence and relative numbers of certain types can shed light particularly on the range of medical and surgical interventions that could have been attempted. Thus, while the composition of most of the complete instrumentaria implies that their users encompassed all three branches into which medicine was traditionally divided--dietetics, drugs and surgery--the composition of other sets suggests that they were used by practitioners who specialised in a single operation or a restricted range of treatments, as, for example, dentistry, lithotomy and eye diseases.

Archaeology↗