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Biomedical subjects

A Dobson

Publications and source records attributed to A Dobson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Whose diet has changed?

The same questions about diet were asked in two community-based surveys conducted in the Hunter Region of New South Wales in 1983 and 1994. There were substantial changes in diet over the period; for example, the proportion of respondents who reported using low-fat or skim milk increased from 25 per cent to 51 per cent, the proportion eating meat fewer than five times a week doubled from 21 per cent to 42 per cent and the proportion eating fewer than three eggs per week increased from 55 per cent to 80 per cent. In both surveys, women reported eating a healthier diet than men, and older people and those of higher socioeconomic status reported better diets than younger people or people with less education or lower status occupations. The surprising finding was that over the 11-year period the changes in patterns of food consumption were remarkably similar across all strata of the population. The conclusions are that wide-spread dietary change is possible. However, the changes in the last decade related mainly to reducing the risk of cardiovascular disease; similar behavioural changes to reduce the risk of diet-related cancer are required.

Adult↗
PubMed1997

Food habits of young and middle-aged women living outside the capital cities of Australia.

Young (18-22 years) and middle-aged (45-49 years) women living in urban and rural areas of New South Wales completed a brief food frequency questionnaire as part of a wider health survey. Urban women in both age groups consumed meat less frequently than women in rural areas, and women in the less populated rural areas were more likely to eat green and yellow vegetables and least likely to eat dried beans. There were few other geographic differences in food habits. Middle-aged women consumed reduced-fat milk, fruit, vegetables, fish, biscuits and cakes significantly more frequently, and rice, pasta, full-cream milk, fried food and take-away food less frequently than younger women. Smokers in both age groups consumed fresh fruit, vegetables and breakfast cereals significantly less frequently than non-smokers, and women with low levels of habitual physical activity consumed fresh fruit and cereals less frequently than more active women. The findings suggest that strategies aimed at changing eating behaviours should be age-group-specific and targeted specifically to smokers and less active women.

Adolescent↗
PubMed1997

Regulation of Laccase Gene Transcription in Trametes versicolor.

The expression of laccase in the white rot fungus Trametes versicolor is regulated at the level of gene transcription by copper and nitrogen. We used reverse transcription-PCR to demonstrate that as the concentration of copper or nitrogen in fungal cultures was increased, an increase in laccase activity, corresponding to increased laccase gene transcription levels, was observed. In addition, we demonstrated that the amounts of laccase mRNA and laccase activity in 10-day-old cultures were a direct function of the concentration of either 1-hydroxybenzotriazole, a previously described laccase substrate, or 2,5-xylidine, a well-known laccase inducer, in the medium. No induction was observed after the addition of two aromatic acids, ferulic acid and veratric acid, which have been shown to induce laccase production in other white rot fungi. When either copper, 2,5-xylidine, or both compounds were added to cultures grown in the absence of copper, increased laccase transcript levels were detected within 15 min. Corresponding increases in laccase activity were observed after 24-h incubation only when copper was present.

Journal Article↗
PubMed1997

Working and living conditions of construction workers: comparison between large and small construction sites in northeastern Thailand.

This study examined differences in working and living conditions of construction workers in large and small construction sites in Northeastern Thailand. Data were collected by questionnaires, through observation and interviewing. A total of 812 construction workers from 20 large sites and 24 small sites were studied. Working and living conditions among the construction workers were generally poor. However, they were better at the large sites than the small ones. The data suggest an urgent need to improve sanitation and safety conditions on the construction sites and camp sites, including personal protective devices and improved welfare for the workers and their families.

Adolescent↗
PubMed1996

Relations of changes in coronary disease rates and changes in risk factor levels: methodological issues and a practical example.

One of the main hypotheses of the World Health Organization (WHO) MONICA Project is that trends in the major coronary disease risk factors are related to trends in rates of fatal and non-fatal coronary disease events. The units of study are populations rather than individuals. The WHO MONICA Project involves continuous monitoring of all coronary disease events in the populations over a 10-year period and periodic risk factor surveys in random samples of the same populations. Estimation of associations between average annual changes in mortality and risk factor levels is illustrated with the use of data from a subset of MONICA centers. Crude estimates of regression coefficients are compared with estimates obtained by weighting for standard errors in both the outcome and explanatory variables. The results show that the strength of association may be either underestimated or overestimated if these errors are not taken into account.

Adult↗
PubMed1996

Physical medicine and rehabilitation workforce study: the supply of and demand for physiatrists.

OBJECTIVE: Analysis, results, and implications of a supply and demand workforce model for physical medicine and rehabilitation. Explicit issues addressed include: (1) the supply implications of maintaining current (1994-1995) output of physiatrists from residency programs; (2) the implications of continued growth in managed care on the demand for the services of physiatrists; (3) likely future supply and demand conditions; and (4) strategies to adapt to future conditions. DESIGN: A workforce model of the supply and demand for physiatrists was developed. Parameters of the model are estimated using econometric models and by applying the judgments of a consensus panel. The model evaluated several different scenarios regarding managed care growth, competition from other providers and other factors. RESULTS: Based on the analysis, physiatrists will continue to be in excess demand through the year 2000. More aggressive growth in managed care can affect this result. CONCLUSIONS: Based on an overall assessment of supply and demand conditions, and under the assumption that the supply of new entrants each year remains in the range of 1994-1995 levels, demand for physiatrists will continue to exceed supply, on average, through the year 2000. Excess supply has, and will, emerge in selected geographic areas. If the profession is successful in informing the market regarding the advantages of physiatry, the profession can continue to grow without experiencing excess supply, in the aggregate, for the foreseeable future.

Forecasting↗
PubMed1996

Risk factors for peptic ulcer in Shanghai.

OBJECTIVES: To investigate the combined effects of Helicobacter pylori infection and traditional risk factors for peptic ulcer. METHODS: A case-control study was conducted in chemical factories in Shanghai, China. The cases were 500 people with peptic ulcer randomly selected from all staff who met the selection criteria. The controls were 500 employees randomly selected from the same factories as the cases. RESULTS: The infection rate for H. pylori was 81% among the cases and 70% among the controls and 85% of all ulcers were duodenal. Current cigarette smoking was common among male cases (80%) and male controls (64%). Univariate analysis suggested that male gender, age, lower socioeconomic status, cigarette smoking, family history of peptic ulcer and infection with H. pylori were all associated with increased risk of peptic ulcer. Separate analyses were performed by sex and occupational group to avoid confounding by cigarette smoking and age. Multivariate analyses showed that for all women and for male staff members, only family history was significantly predictive of peptic ulcer or duodenal ulcer. Among male workers or drivers, however, all the major risk factors were statistically significantly associated with increased risk. CONCLUSIONS: In a population where the rate of infection with H. pylori is high, the traditional risk factors for peptic ulcer or duodenal ulcer (i.e. family history, male gender, increasing age, lower socioeconomic status and cigarette smoking) are still significant predictors of increased risk of ulcer. If men with ulcers (or with a family history of peptic ulcer) gave up cigarette smoking, morbidity could be reduced in this population.

Adult↗
PubMed1996

Oxidation of Anthracene and Benzo[a]pyrene by Laccases from Trametes versicolor.

The in vitro oxidation of the two polycyclic aromatic hydrocarbons anthracene and benzo[a]pyrene, which have ionization potentials of <=7.45 eV, is catalyzed by laccases from Trametes versicolor. Crude laccase preparations were able to oxidize both anthracene and the potent carcinogen benzo[a]pyrene. Oxidation of benzo[a]pyrene was enhanced by the addition of the cooxidant 2,2(prm1)-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS), while an increased anthracene oxidizing ability was observed in the presence of the low-molecular-weight culture fluid ultrafiltrate. Two purified laccase isozymes from T. versicolor were found to have similar oxidative activities towards anthracene and benzo[a]pyrene. Oxidation of anthracene by the purified isozymes was enhanced in the presence of ABTS, while ABTS was essential for the oxidation of benzo[a]pyrene. In all cases anthraquinone was identified as the major end product of anthracene oxidation. These findings indicate that laccases may have a role in the oxidation of polycyclic aromatic hydrocarbons by white rot fungi.

Journal Article↗
PubMed1996

Pulmonary capillary pressure during exercise in horses.

The object of this study was to relate pulmonary capillary pressure to arterial and wedge pressures during exercise. Pulmonary vascular pressures were measured in six standardbred horses exercising at speeds equivalent to 75, 90, and 100% of maximal heart rate. Vascular pressures were measured with transducer-tip catheters and expressed relative to esophageal pressure. Pulmonary capillary pressure was estimated by the arterial-occlusion technique modified for exercise. Mean pulmonary arterial, capillary and wedge pressures increased from 30.5 +/- 6.3, 17.8 +/- 4.3, and 13.4 +/- 1.6 mmHg, respectively, at rest, to 70.5 +/- 5.2, 42.1 +/- 5.3, and 38.4 +/- 5.6 mmHg, respectively, at maximal exercise. The largest part of the increase occurred during the first level of exertion. With exercise, the pressure across the lung barely doubled at a time when the cardiac output would have increased at least fivefold. Thus the absolute resistance in both pre- and postcapillary segments must have decreased. The capillary and wedge pressures rose similarly, whereas the difference between them did not change with exertion. The fractional resistance of the precapillary segment increased with exercise. The postcapillary resistance, initially 28% of the total pulmonary vascular resistance, fell to 9% at maximal exercise. The rise (to approximately 45 mmHg) in pulmonary capillary pressure with exertion is consistent with an increase in transvascular filtration.

Animals↗
PubMed1996

The impact of managed care on clinical research: a preliminary investigation.

Rapid growth in managed care enrollment is likely to affect clinical research at the nation's academic medical centers (AMCs). Our site visit interviews indicate that managed care has not markedly reduced coverage for research-related care. However, market competition in some areas has limited AMCs' ability to subsidize research activities with clinical revenues. As they gain market share, managed care organizations will have a growing influence on research priorities. Therefore, it is important for the academic community to work with managed care leaders to identify areas for collaboration and an agenda for moving forward in the future.

Academic Medical Centers↗
PubMed1996

Risk-adjusted Medicare capitation rates using ambulatory and inpatient diagnoses.

Researchers at The Johns Hopkins University (JHU) developed two new diagnosis-oriented methodologies for setting risk adjusted capitation rates for managed care plans contracting with Medicare. These adjusters predict the future medical expenditures of aged Medicare enrollees based on demographic factors and diagnostic information. The models use the Ambulatory Care Group (ACG) algorithm to categorize ambulatory diagnoses. Two alternative approaches for categorizing inpatient diagnoses were used. Lewin-VHI, Inc. evaluated the models using data from 624,000 randomly selected aged Medicare beneficiaries. The models predict expenditures far better than the Adjusted Average per Capita Cost (AAPCC) payment method. It is possible that risk adjusted capitation payments could encourage health plans to compete on the basis of efficiency and quality and not risk selection.

Aged↗
PubMed1995

Persistence and transmission of tick-borne viruses: Ixodes ricinus and louping-ill virus in red grouse populations.

The population dynamics of tick-borne disease agents and in particular the mechanisms which influence their persistence are examined with reference to the flavivirus that causes louping-ill in red grouse and sheep. Pockets of infection cause heavy mortality and the infection probably persists as a consequence of immigration of susceptible hosts. Seroprevalence is positively associated with temporal variations in vectors per host, although variation between areas is associated with the abundance of mountain hares. The presence of alternative tick hosts, particularly large mammals, provides additional hosts for increasing tick abundance. Grouse alone can not support the vectors and the pathogen but both can persist when a non-viraemic mammalian host supports the tick population and a sufficiently high number of nymphs bite grouse. These alternative hosts may also amplify virus through non-viraemic transmission by the process of co-feeding, although the relative significance of this has yet to be determined. Another possible route of infection is through the ingestion of vectors when feeding or preening. Trans-ovarial transmission is a potentially important mechanism for virus persistence but has not been recorded with louping-ill and Ixodes ricinus. The influence of non-viraemic hosts, both in the multiplication of vectors and the amplification of virus through non-viraemic transmission are considered significant for virus persistence.

Animals↗
PubMed1995

QT dispersion does not predict early ventricular fibrillation after acute myocardial infarction.

Ventricular arrhythmias may be associated with increased QT dispersion (difference between maximum and minimum QT on standard 12-lead ECG). We performed a case control study to determine if QT dispersion on the admission ECG could predict early VF after acute myocardial infarction. The cases were 24 patients with acute myocardial infarction (14 inferior, 8 anterior, and 2 lateral) with VF within 12 hours of admission. There were 24 control patients without VF matched for site of infarction and ST segment score (sum of ST segment elevation). VF occurred a median of 153 minutes (interquartile range 93-245) after onset of chest pain and 33 minutes (range 7-104) after initial ECG. QT (399 +/- 37 and 394 +/- 37), QT corrected (440 +/- 38 and 429 +/- 29), and QT dispersion (68 +/- 20 and 66 +/- 27) were similar in patients and controls. By design, ST score was similar (11 +/- 9 vs 9 +/- 5 mV), although a good match could not be obtained for three patients with extreme ST elevation. Patients with VF presented to the hospital earlier after the onset of chest pain (median 95 min [range 65-188] compared to 150 min [range 80-270], P = 0.05) and had a lower serum sodium (138 +/- 2.4 vs 140 +/- 2.5, P = 0.05) than controls. Thus, QT interval and QT dispersion, measured on the presenting ECG, did not predict early VF after myocardial infarction.

Aged↗
PubMed1995

Metabolic adaptations for desert survival in the Bedouin goat.

Energy conservation is a key adaptation for desert survival in the Bedouin goat. When food is scarce, metabolism is reduced and body weight can be maintained indefinitely on less than one-half of normal intake. We hypothesized that metabolism would be turned down during both rest and exercise, but it was not. It was low when animals rested and returned to normal during exercise. We expected catecholamines and thyroid hormones would modulate metabolism, but they did not. The reduction in metabolism preceded any change in thyroid hormone concentrations, and infusions of epinephrine did not restore reduced metabolism to normal levels. Finally, we expected the gut would be the major organ system involved in the metabolic reduction because less food is eaten, processed, and absorbed. Contrary to our expectations, we found that muscle is the primary organ system responsible for the reduction. It appears that the adaptations of the Bedouin goat for surviving on limited food supplies involve different organ systems and different modulators to reduce metabolism from those known for other mammals.

Adaptation, Physiological↗
PubMed1994

The population dynamics of parasitic helminth communities.

This paper describes a mathematical model which allows us to compare the data collected from short-term cross-sectional surveys with the population dynamics of host and parasite populations over longer periods of time. The model extends an earlier framework for two parasite species in one host, to one for an arbitrary number of parasite species. We show that the conditions necessary for the coexistence of two parasite species extend to expressions for the coexistence of three or more parasite species. Furthermore, the model suggests that those species which form the 'core' of the parasite community are those whose high fecundity and transmission efficiency permit them to colonize hosts readily. In contrast, those species which are classified as 'satellite' species of the community are either species with low fecundity, or low transmission efficiencies. This work confirms earlier studies that suggest that increasing degrees of aggregation are crucial in allowing several species of parasites to coexist in the same species of hosts. The properties of the model are compared with patterns observed in data collected for helminth parasites of Anolis lizards, wood mice and eels. This combined theoretical and empirical approach confirms the importance of the life history strategies of the parasite in determining the abundance of each species in the community. It suggests that studies of parasite community structure have to pay more attention to the strategies pursued by each individual species before interactions between species are considered.

Animals↗