Biomedical subjects
Publications and source records attributed to M Dunne.
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We present differential x-ray scattering cross sections for a radiatively heated plasma showing overall consistency, in both form and absolute value, with theoretical simulations. In particular, the evolution of the plasma from a strongly coupled high density phase to a lower density weakly coupled phase is quite clearly shown in both experiment and simulation. The success of this experiment shows that x-ray scattering has the potential to become an extremely useful diagnostic technique for dense plasma physics.
We present a new approach to indirect-drive inertial confinement fusion which makes use of highly supersonic, radiatively cooled, slugs of plasma to energize a hohlraum. 2D resistive magnetohydrodynamic simulations of slug formation in shaped liner Z-pinch implosions are presented along with 2D-radiation-hydrodynamic simulations of the slug impacting a converter foil and 3D-view-factor simulations of a double-ended hohlraum. Results for the Z facility at Sandia National Laboratory indicate that two synchronous slugs of 250 kJ kinetic energy could be produced, resulting in a capsule surface temperature of approximately 225 eV.
The importance of the research on Bioregenerative Life Support has increased dramatically in the last decade not only with regard to possible space flight application but also as a way to obtain a better understanding of our Earth's ecology. A major goal was to reach long-term stability of artificial model systems. Preliminary data are presented on the development of an improved aquatic system, currently dedicated for ground-based research. Closed aquatic ecosystems require reliability of the key parameters of pH, O2 and CO2 concentration and stability of sensors for monitoring. Besides the integration of an artificial lung (holofiber system and air pump with valves, allowing controlled oxygen uptake of air), in parallel to the oxygen producing water plants. Our new approach is to implement opto-chemical sensors, for such environmental monitoring. One major advantage of the new sensor technique is their better long-term reliability as compared to the electrochemical sensors. Our experiment with the new sensor technique has demonstrated satisfactory performance in closed aquatic ecosystems.
Ophthalmophakometric measurements of ocular surface radius of curvature and alignment were evaluated on physical model eyes encompassing a wide range of human ocular dimensions. The results indicated that defocus errors arising from imperfections in the ophthalmophakometer camera telecentricity and light source collimation were smaller than experimental errors. Reasonable estimates emerged for anterior lens surface radius of curvature (accuracy: 0.02-0.10 mm; precision 0.05-0.09 mm), posterior lens surface radius of curvature (accuracy: 0.10-0.55 mm; precision 0.06-0.20 mm), eye rotation (accuracy: 0.00-0.32 degrees; precision 0.06-0.25 degrees), lens tilt (accuracy: 0.00-0.33 degrees; precision 0.05-0.98 degrees) and lens decentration (accuracy: 0.00-0.07 mm; precision 0.00-0.07 mm).
A five-center study was conducted with the aim of determining how reproducibly expectorated sputa and tracheal aspirates could be sampled when preparing Gram-stained smears and inoculating cultures. With both specimen types, excessive variation was noted among Gram stain results obtained from replicate smears. Less variation was noted among culture results, especially with tracheal aspirates.
Parkinson's disease is a common neurological disease and its prevalence increases with age. Because of an ageing population and changing environment compared to the last epidemiological study done in Australia over 30 years ago, we have conducted a door-to-door pilot survey which looked at the latest prevalence as well as putative risk factors in a random population. We used a two-phase investigation method (screening followed by detailed examination) in a random community sample of 2,820 households (with 527 individuals aged 55 and over) along with 203 residents in aged care facilities (single-phase examination for residents aged 55 and above) in the Randwick area of Sydney, New South Wales. We had a 75% participation rate in the community and a 94% in the aged care facilities. The results of the survey in this sample of 730 subjects indicated that the crude prevalence of Parkinson's disease was between 3.6 and 4.9% (higher in the aged care facilities). The putative risk factors positively identified using chi-square method were 'family history' (p < 0.01) and 'exposure to chemicals at work or in surrounding environment' (p < 0.05). The age-adjusted prevalence rate of Parkinson's disease revealed at least a 42.5% increase in the disease compared to 1966. We conclude that there may be an increase in the disease in Australia due to ageing and other risk factors.
Chloroquine-resistant Plasmodium vivax has been the subject of numerous case reports and prospective studies from Oceania and Asia. In contrast, only case reports exist from the Americas. We performed a prospective study with 28-day follow-up of clinical responses to chloroquine in 2 P. vivax-endemic regions of Colombia. Three (11%) of 27 patients failed to respond to treatment with the standard regimen of chloroquine (1,500 mg of base over 3 days). One patient demonstrated RI resistance on Day 26; one patient demonstrated RI resistance due to recrudescence of blood stages on Day 11; and one patient demonstrated RII resistance of blood stages by never displaying clearing of peripheral parasitemia. All patients were successfully treated with primaquine, which has some blood stage efficacy against P. vivax, combined with a second course of chloroquine. Clinical resistance of P. vivax to chloroquine is present in Colombia and should be monitored in the Americas.
Two hundred and forty-six patients infected with human immunodeficiency virus (HIV) who also had disseminated Mycobacterium avium complex received either azithromycin 250 mg every day, azithromycin 600 mg every day, or clarithromycin 500 mg twice a day, each combined with ethambutol, for 24 weeks. Samples drawn from patients were cultured and clinically assessed every 3 weeks up to week 12, then monthly thereafter through week 24 of double-blind therapy and every 3 months while on open-label therapy through the conclusion of the trial. The azithromycin 250 mg arm of the study was dropped after an interim analysis showed a lower rate of clearance of bacteremia. At 24 weeks of therapy, the likelihood of patients' developing 2 consecutive negative cultures (46% vs. 56%, P=.24) or 1 negative culture (59% vs. 61%, P=.80) was similar for azithromycin 600 mg (n=68) and clarithromycin (n=57), respectively. The likelihood of relapse was 39% versus 27% (P=.21) on azithromycin compared with clarithromycin, respectively. Of the 6 patients who experienced relapse, none of those randomized to receive azithromycin developed isolates resistant to macrolides, compared with 2 of 3 patients randomized to receive clarithromycin [corrected]. Mortality was similar in patients comprising each arm of the study (69% vs. 63%; hazard, 95.1% confidence interval, 1.1 [0.7, 1.7]). Azithromycin 600 mg, when given in combination with ethambutol, is an effective agent for the treatment of disseminated M. avium disease in patients infected with HIV.
For many years, ivermectin has been widely distributed throughout west Africa for the safe and effective control of onchocerclasis. However, recent events in Loa-loa-endemic areas of Cameroon, where severe adverse reactions have occurred, now constrain the public-health use of this drug in the forest habitat of the L. loa vector. We have created a model of L. loa prevalence to identify areas where high endemicity may be associated with the occurrence of such reactions. The model results have been mapped and the areas of overlap between high L. loa prevalence and planned ivermectin distribution for onchocerciasis control identified.
Polymer degradation usually plays a crucial role in drug release from sustained release polyester systems, therefore in order to elucidate the mechanism governing release, it appears essential to analyse the in vitro degradation behaviour of these devices. In this study the influence of processing conditions, particle characteristics and release media temperature on the degradation of PLGA spherical particles were examined. It was found that a linear relationship between the degradation rate and particle size existed, with the larger particles degrading fastest. In smaller particles degradation products formed within the particle can diffuse easily to the surface while in larger particles degradation products have a longer path to the surface of the particle during which autocatalytic degradation of the remaining polymer material can occur. The influence of release media temperature on the degradation of PLGA particles was also examined. At lower incubation temperatures PLGA microparticles showed an induction period after which polymer degradation proceeded. The rate of polymer degradation was found to increase with increasing incubation temperature. The polymer erosion profile was fitted to the Prout-Tompkins equation and the rate constants were used to determine the activation energy of PLGA hydrolysis.
Following the claim by some anthropologists and sociologists that 1 symbolic meaning of meat is a preference for hierarchical domination (C. J. Adams, 1990; N. Fiddes, 1989; D. D. Heisley, 1990; J. Twigg, 1983), the authors compared the values and beliefs of vegetarians and omnivores in 2 studies conducted in New Zealand. They compared the full range of vegetarians and omnivores on right-wing authoritarianism, social dominance orientation, human values, and consumption values. The participants tending toward omnivorism differed from those leaning toward veganism and vegetarianism in 2 principal ways: The omnivores (a) were more likely to endorse hierarchical domination and (b) placed less importance on emotional states. Accordingly, the acceptance or rejection of meat co-varied with the acceptance or rejection of the values associated with meat; that finding suggests that individuals consume meat and embrace its symbolism in ways consistent with their self-definitions.
AIMS: A modified version of the Mental Adjustment to Cancer Scale (The Mental Adjustment to HIV Scale--MAHIVS) was used to evaluate patterns of psychological adjustment in response to HIV infection. METHODS: A sample of 164 HIV positive homosexual/bisexual men were recruited across three Australian centers (79 asymptomatic (CDC II/III) and 85 symptomatic HIV infection (CDC IV)). Factor analysis of the MAHIVS was conducted and the predictive validity of the MAHIVS was investigated using the General Health Questionnaire, while The Diagnostic Interview Schedule was used to assess current and lifetime psychiatric disorder. Other measures of adjustment/coping were used to investigate the construct validity of the MAHIVS (neuroticism, locus of control, defense style). RESULTS: Factor analysis of the MAHIVS detected four factors: Hopelessness, Fighting Spirit/Self Efficacy, Personal Control, and Minimization. Hopelessness and Fighting Spirit factors exhibited acceptable levels of internal consistency and validity, with significant correlations detected with psychological symptoms and significant association with other measures of psychological adjustment and personality. Fighting Spirit emerged as a potential indicator of psychological resilience, whereas Hopelessness was significantly associated with psychological symptoms and current major depression (but not past depression). CONCLUSIONS: The findings indicate the validity of the MAHIVS and support the presence of common themes in the psychological adaptation to life-threatening illness that can be detected across disease categories and groups.
Clinical trials to assess the merit of antibiotic intervention in the treatment of ischemic cardiovascular disease are now underway, spurred on by an association between Chlamydia pneumoniae and atherogenesis noted in epidemiologic investigations, histopathologic studies, and results from various animal models. The design of such clinical trials must take into account a number of issues: the primary event as strictly defined by objective criteria, the event rate in the chosen population, the potential treatment effect, the availability of patients, the underlying cause of their atherosclerotic disease, the determination of the C pneumoniae-infected population to study, the dose and duration of the antibiotic, and the length of follow-up. In the design of the WIZARD study (Weekly Intervention with Zithromax for Atherosclerosis and its Related Disorders), an attempt was made to take these issues under consideration. Patients were randomly assigned either to 600 mg/d zithromax for 3 days then 600 mg/wk for 11 additional weeks or to placebo. Patients in the study had a myocardial infarction at least 6 weeks previously, had no recent coronary artery bypass graft or percutaneous transluminal coronary angioplasty, and did not required long-term administration of antibiotics. Patients were required to have an immunoglobulin G titer to C pneumoniae of >/=1:16. The primary end point was the time to a composite of all-cause death, myocardial infarction, a revascularization procedure, or hospitalization for angina. The study enrolled 3500 patients, sufficient to detect a 25% reduction in the presumed 8% placebo event rate with 90% power. Follow-up will continue through the prespecified number of end points.
This study investigated the psychological impact of HIV infection through assessment of posttraumatic stress disorder in response to HIV infection. Sixty-one HIV-positive homosexual/bisexual men were assessed for posttraumatic stress disorder in response to HIV infection (PTSD-HIV) using a modified PTSD module of the DIS-III-R. Thirty percent met criteria for a syndrome of posttraumatic stress disorder in response to HIV diagnosis (PTSD-HIV). In over one-third of the PTSD cases, the disorder had an onset greater than 6 months after initial HIV infection diagnosis. PTSD-HIV was associated with other psychiatric diagnoses, particularly the development of first episodes of major depression after HIV infection diagnosis. PTSD-HIV was significantly associated with a pre-HIV history of PTSD from other causes, and other pre-HIV psychiatric disorders and neuroticism scores, indicating a similarity with findings in studies of PTSD from other causes. The findings from this preliminary study suggest that a PTSD response to HIV diagnosis has clinical validity and requires further investigation in this population and other medically ill groups. The results support the inclusion of the diagnosis of life-threatening illness as a traumatic incident that may lead to a posttraumatic stress disorder, which is consistent with the DSM-IV criteria.
During the past 6 to 7 years, the problem of antimicrobial resistance in Streptococcus pneumoniae has grown dramatically in the United States. Currently, approximately 26.5% of pneumococcal isolates express intermediate levels of resistance to penicillin; approximately 17.5% are highly penicillin resistant. We studied whether clonal relationships exist among current isolates of high-level penicillin-resistant S. pneumoniae (PRSP) in the United States. One hundred forty-seven PRSP isolates recovered in a 30-center surveillance study in the United States during 1994-1995 were characterized with respect to serotype, antimicrobial susceptibility pattern, and pulsed-field gel electrophoresis (PFGE) profile. Only six serotypes were observed among the 147 PRSP isolates examined in this study: 6A, 6B, 9A, 14, 19F, and 23F. One hundred three (70.1%) of the 147 strains were characterized by one of only nine PFGE types; 76 (51.7%) of the 147 isolates were characterized by only four PFGE profiles. Currently in the United States, most PRSP strains are represented by relatively few clonal groups.
OBJECTIVE: This study aimed to investigate rates of psychiatric disorder in human immunodeficiency virus (HIV) infection, in an Australian sample of homosexual and bisexual men. METHOD: A cross-sectional study of a total of 65 HIV sero-negative (HIV-) and 164 HIV sero-positive men (HIV+) (79 CDC stage II/III and 85 CDC stage IV) was conducted in three centres. Lifetime and current prevalence rates of psychiatric disorder were evaluated using the Diagnostic Interview Schedule Version IIIR (DIS-IIIR). RESULTS: Elevated current and lifetime rates of major depression were detected in both HIV negative and HIV positive homosexual/bisexual men. Lifetime rates of alcohol abuse/dependence were significantly elevated in HIV positive men (CDC group IV) when compared with HIV negative men. Among the HIV positive group the majority of psychiatric disorders detected were preceded by a pre-HIV diagnosis of psychiatric disorder. Major depression represented the disorder most likely to have first onset after HIV infection diagnosis. CONCLUSIONS: Lifetime rates of major depression were elevated in this sample of HIV-negative and HIV-positive men. In the HIV-positive men, psychiatric disorder was significantly associated with the presence of lifetime psychiatric disorder prior to HIV infection diagnosis. The findings indicate the importance of evaluation of psychiatric history prior to HIV infection and the clinical significance of depressive syndromes in this population.
A method is described for a fully automated, sensitive, accurate and precise assay for the determination of sumatriptan in human serum. The assay consists of solid-phase extraction followed by reversed-phase HPLC with electrochemical detection. The extraction procedure has been fully automated on a Zymate XP robot linked on-line to the HPLC system. The assay is linear over the analytical range 1-30 ng ml-1 and selective for sumatriptan with respect to endogenous plasma components and GR49336, the major circulating metabolite. The intra-assay data demonstrate a maximum bias and precision across the calibration range of 10% and 6.6% respectively. The inter-assay data demonstrate a maximum bias and precision across the calibration range of 6.7% and 8.8%, respectively. The extraction efficiency of the assay is approximately 90% and is constant across the calibration range. The assay was used for the determination of sumatriptan in serum clinical samples and was shown to be robust in sustained use over several months. The use of a Zymate XP robot allowed complete automation of the assay, which resulted in high-quality, high-throughput analyses.