Search PubMed⌕ Search

Biomedical subjects

Patrick Phillips

Publications and source records attributed to Patrick Phillips.

At least 19 recordsLinked to original sources
PubMed2006

Do people with risky behaviours participate in biomedical cohort studies?

BACKGROUND: Analysis was undertaken on data from randomly selected participants of a bio-medical cohort study to assess representativeness. The research hypotheses was that there was no difference in participation and non-participations in terms of health-related indicators (smoking, alcohol use, body mass index, physical activity, blood pressure and cholesterol readings and overall health status) and selected socio-demographics (age, sex, area of residence, education level, marital status and work status). METHODS: Randomly selected adults were recruited into a bio-medical representative cohort study based in the north western suburbs of the capital of South Australia--Adealide. Comparison data was obtained from cross-sectional surveys of randomly selected adults in the same age range and in the same region. The cohort participants were 4060 randomly selected adults (18+ years). RESULTS: There were no major differences between study participants and the comparison population in terms of current smoking status, body mass index, physical activity, overall health status and proportions with current high blood pressure and cholesterol readings. Significantly more people who reported a medium to very high alcohol risk participated in the study. There were some demographic differences with study participants more likely to be in the middle level of household income and education level. CONCLUSION: People with risky behaviours participated in this health study in the same proportions as people without these risk factors.

Adult↗
PubMed2006

How valid are self-reported height and weight? A comparison between CATI self-report and clinic measurements using a large cohort study.

OBJECTIVE: To examine the relationship between self-reported and clinical measurements for height and weight in adults aged 18 years and over and to determine the bias associated with using household telephone surveys. METHOD: A representative population sample of adults aged 18 years and over living in the north-west region of Adelaide (n = 1,537) were recruited to the biomedical cohort study in 2002/03. A computer-assisted telephone interviewing (CATI) system was used to collect self-reported height and weight. Clinical measures were obtained when the cohort study participants attended a clinic for biomedical tests. RESULT: Adults over-estimated their height (by 1.4 cm) and under-estimated their weight (by 1.7 kg). Using the self-report figures the prevalence of overweight/ obese was 56.0% but this prevalence estimate increased to 65.3% when clinical measurements were used. The discrepancy in self-reported height and weight is partly explained by 1) a rounding effect (rounding height and weight to the nearest 0 or 5) and 2) older persons (65+ years) considerably over-estimating their height. CONCLUSION: Self-report is important in monitoring overweight and obesity; however, it must be recognised that prevalence estimates obtained are likely to understate the problem. IMPLICATIONS: The public health focus on obesity is warranted, but self-report estimates, commonly used to highlight the obesity epidemic, are likely to be underestimations. Self-report would be a more reliable measure if people did not round their measurements and if older persons more accurately knew their height.

Adolescent↗
PubMed2005

Empowering patients with essential information and communication support in the context of diabetes.

OBJECTIVES: Patients with diabetes need to be aware of essential information to be involved in decision-making, manage diabetes properly, and communicate with doctors and other healthcare providers effectively. We have developed Violet Technology (VT) to provide features beyond previous health information tailoring systems by dynamically prioritizing diabetes learning topics and providing integrated direct support for patient-provider communication through formulation of individualized agendas to take to healthcare encounters. METHODS: A particular feature of the VT approach is a Diabetes Information Profile (DIP) that models psychosocial and educational exposure features, as well as clinical characteristics, and considers expressed patient information preferences and recent information browsing history. The agenda facility recommends questions that the patients may have based on their profile, as well as helping to initialize a patient empowerment protocol. The technology uses a modular and extensible approach for key components, including consumer health information, prioritization rules, and methods of instantiating the DIP. VT has been implemented into a web portal for patient use. Two phases of evaluation studies have been conducted to collect patient and healthcare provider feedback. RESULTS AND CONCLUSIONS: Results indicate that VT prioritizes relevant and important information for individual patients. Moreover, both patients and providers indicate that formulating an agenda of questions is important for patients. More extensive system use is needed to establish if the technology can deliver an improved patient-provider partnership and, ultimately, improved health outcomes.

Adult↗
PubMed2005

Accuracy and power of the likelihood ratio test for comparing evolutionary rates among genes.

Sequences for multiple protein-coding genes are now commonly available from several, often closely related species. These data sets offer intriguing opportunities to test hypotheses regarding whether different types of genes evolve under different selective pressures. Although maximum likelihood (ML) models of codon substitution that are suitable for such analyses have been developed, little is known about the statistical properties of these tests. We use a previously developed fixed-sites model and computer simulations to examine the accuracy and power of the likelihood ratio test (LRT) in comparing the nonsynonymous-to-synonymous substitution rate ratio (omega = dN/dS) between two genes. Our results show that the LRT applied to fixed-sites models may be inaccurate in some cases when setting significance thresholds using a chi(2) approximation. Instead, we use a parametric bootstrap to describe the distribution of the LRT statistic for fixed-sites models and examine the power of the test as a function of sampling variables and properties of the genes under study. We find that the power of the test is high (>80%) even when sampling few taxa (e.g., six species) if sequences are sufficiently diverged and the test is largely unaffected by the tree topology used to simulate data. Our simulations show fixed-sites models are suitable for comparing substitution parameters among genes evolving under even strong evolutionary constraint (omega approximately 0.05), although relative rate differences of 25% or less may be difficult to detect.

Biological Evolution↗
PubMed2004

Detection of retained microbubbles in carotid arteries with real-time low mechanical index imaging in the setting of endothelial dysfunction.

OBJECTIVES: We sought to determine if intravenously injected microbubbles would be retained by the carotid arteries (CAs) in the setting of endothelial dysfunction (ED) using a linear transducer equipped with a low mechanical index pulse sequence scheme (PSS). BACKGROUND: Microbubbles normally pass freely through large and small vessels but are retained in regions with ED. New high-frequency low mechanical index PSS can potentially be utilized to image these retained microbubbles. METHODS: Intravenous albumin- and lipid-encapsulated microbubbles were administered in seven pigs while imaging the CAs before and after a 20% intralipid infusion to induce hypertriglyceridemia. The degree of microbubble retention was quantified by measuring endothelial acoustic intensity (AI) after clearance of free-flowing microbubbles. Microbubble adherence was also evaluated after selective balloon injury of the CAs. The CA diameter responses to acetylcholine were quantified. RESULTS: After induction of hypertriglyceridemia, adherence of albumin-encapsulated microbubbles was visually evident in all CAs, and endothelial AI increased significantly (p < 0.001 compared with baseline). The CA responses to acetylcholine went from vasodilation at baseline to vasoconstriction during hypertriglyceridemia. Endothelial AI also increased in the balloon-stretched vessels (p < 0.01 compared with uninjured vessels) after albumin-encapsulated microbubble injection, with a ring of microbubbles selectively adhering to the injured segment. This retention was not observed with lipid-encapsulated microbubbles. Scanning electron microscopy confirmed that albumin-coated microbubbles adhered to endothelial cells. CONCLUSIONS: Retention of intravenously injected albumin microbubbles occurs in the setting of both global and regional ED in large vessels and can be noninvasively imaged with high-frequency low mechanical index PSS.

Acoustics↗
PubMed2004

Parallel genetic basis for repeated evolution of armor loss in Alaskan threespine stickleback populations.

Most adaptation is thought to occur through the fixation of numerous alleles at many different loci. Consequently, the independent evolution of similar phenotypes is predicted to occur through different genetic mechanisms. The genetic basis of adaptation is still largely unknown, however, and it is unclear whether adaptation to new environments utilizes ubiquitous small-effect polygenic variation or large-effect alleles at a small number of loci. To address this question, we examined the genetic basis of bony armor loss in three freshwater populations of Alaskan threespine stickleback, Gasterosteus aculeatus, that evolved from fully armored anadromous populations in the last 14,000 years. Crosses between complete-armor and low-armor populations revealed that a single Mendelian factor governed the formation of all but the most anterior lateral plates, and another independently segregating factor largely determined pelvic armor. Genetic mapping localized the Mendelian genes to different chromosomal regions, and crosses among these same three widely separated populations showed that both bony plates and pelvic armor failed to fully complement, implicating the same Mendelian armor reduction genes. Thus, rapid and repeated armor loss in Alaskan stickleback populations appears to be occurring through the fixation of large-effect variants in the same genes.

Animals↗
PubMed2004

Microbubble contrast agents for echocardiography: rationale, composition, ultrasound interactions, and safety.

Imaging the small blood vessels within the myocardium, which contains only a small fraction of the total coronary blood volume, is a significant challenge for ultrasound imaging. Recent advances in microbubble design and ultrasound technology have improved our ability to image the microcirculation. It is essential to understand the fundamentals of microbubble behavior in an ultrasound field and how it impacts technology and safety.

Coronary Vessels↗
PubMed2004

Imaging technologies and techniques.

Equipment manufacturers provide contrast-specific detection techniques that have excellent sensitivity and excellent agent-to-tissue specificity along with helpful tools that improve workflow efficiency dramatically. Excellent contrast agents have been approved for LV opacification and are available worldwide. Techniques designed for low-MI imaging offer real-time acquisition capabilities and lead to faster examinations. Techniques designed for medium-MI imaging offer better sensitivity than low-MI techniques while maintaining the benefit of rapid image acquisition. Techniques designed for high-MI imaging offer the best sensitivity with longer acquisition times. These techniques are viable means for imaging contrast agents tailored to clinical needs. Progress by contrast agent manufacturers, equipment manufacturers, and physicians will continue to drive improvements in the areas of detection and clinical workflow for improved patient care.

Coronary Circulation↗
PubMed2004

Osteoporosis--diagnosis, treatment and management.

BACKGROUND: Osteoporosis is common, asymptomatic and usually undetected until a fracture occurs. Fracture, particularly hip fracture, can be associated with significant mortality, morbidity and loss of independence. OBJECTIVE: This article presents a practical case based approach to identify and manage osteoporosis. DISCUSSION: The major risk factors for osteoporosis in men and women are known, and case finding by dual X-ray absorptiometry and treatment with effective medications are subsidized by the commonwealth government. At the menopause, symptomatic women considering oestrogen replacement should assess their individual risk of osteoporosis, cardiovascular events and breast cancer. Men also develop osteoporosis and this should be on the health agenda along with cardiovascular disease, prostate and colon cancer, and diabetes. Treatment should include supplemental calcium and occasionally vitamin D. There is strong evidence for the benefits of bisphosphonates, the selective oestrogen receptor modulators and oestrogen replacement.

Aged↗
PubMed2004

Contrast-agent detection and quantification.

The Cadence contrast pulse sequencing (CPS) technology offers improved clinical information and workflow efficiency during contrast agent examinations. The technology harnesses unique non-linear microbubble energy discovered within the same fundamental frequency band as the transmitted pulses of sound and thus offers improved sensitivity and penetration. An auto tracking contrast quantification (ACQ) technology further complements the CPS detection technology with automatic image alignment during quantification with features such as on-line multiple time intensity curves (TIC). The regional image analysis holds promise of alleviating workflow inefficiency associated with manual alignment of image frames.

Contrast Media↗
PubMed2003

Body mass index, waist hip ratio, and waist circumference: which measure to classify obesity?

OBJECTIVES: To determine the proportion of a representative population sample of adults in South Australia who have a body mass index (a measure of overall obesity) classified as normal or underweight, but who also have a waist circumference or waist hip ration (measures of central obesity) that indicates obesity. METHODS: A representative population sample of adults aged 18 years and over living in the north west region of Adelaide (n = 2523) were recruited to the study. Clinical measures of height, weight, waist and hip circumference were obtained and used to determine body mass index, waist hip ratio and waist circumference. RESULTS: Among women with a normal body mass index, 19.0% had a high waist circumference (> or = 80 cm) and 8.5% had a high waist hip ratio (> 0.85). Among males with a normal body mass index, 3.4% had a high waist circumference (> or = 95 cm) and 0.1% had a high waist hip ratio (> 1.0). CONCLUSIONS: Body mass index, waist hip ratio and waist circumference all have a role in the identification of those who are obese or overweight.

Adolescent↗
PubMed2003

Differences in definity and optison microbubble destruction rates at a similar mechanical index with different real-time perfusion systems.

The purpose of this study was to determine microbubble responses to different pulse sequence schemes that exist on low mechanical index (MI) real-time perfusion imaging systems using either intravenous albumin-coated (Optison) or lipid-encapsulated (Definity) microbubbles. A tissue-mimicking phantom was created that permitted insonation of microbubbles at 3 cm (near field) and 9 cm (far field) from the diagnostic transducer face. Differences in effluent microbubble concentration were measured after they passed through vessels being insonified with pulse sequence schemes that transmitted alternating polarity (pulse inversion Doppler), alternating amplitude (power modulation), or both (contrast pulse sequencing) at a similar MI, frame rate, and transmit frequency. Normalized contrast signal intensity within a recirculating chamber was also measured in the near and far field. Pulse inversion Doppler produced less initial normalized contrast signal intensity and greater destruction rates than amplitude varying pulse sequence schemes like power modulation or contrast pulse sequencing at both the 0.1- and 0.2-MI settings. These differences indicate that the same MI setting on different real-time perfusion imaging techniques will produce different microbubble responses.

Albumins↗
PubMed2003

Acarbose improves glycemic control in overweight type 2 diabetic patients insufficiently treated with metformin.

OBJECTIVE: To investigate the efficacy and safety of acarbose as add-on therapy in overweight type 2 patients with diabetes inadequately controlled by metformin. RESEARCH DESIGN AND METHODS: This study adopted a multicenter, randomized, double-blind, placebo-controlled, parallel group design. After a 4-week placebo run-in period, subjects were randomized to either acarbose (titrated up to 100 mg b.i.d.) or placebo. The primary efficacy variable was the change in HbA(1c) from baseline to the end of the 24-week treatment period. Change in fasting blood glucose was assessed as a secondary efficacy parameter. RESULTS: The intention-to-treat analysis from baseline to week 24 (81 patients for HbA(1c) and 82 for fasting blood glucose) showed statistically significant differences between acarbose and placebo treatment in HbA(1c) (1.02%; 95% CI 0.543-1.497; P = 0.0001) and fasting blood glucose (1.132 mmol/l; 95% CI 0.056-2.208; P = 0.0395) (adjusted least square means). In all, 18 patients (47%) in the acarbose group were classified as responders with a > or =5% reduction in HbA(1c) (relative to baseline) at the end point compared to 6 (14%) in the placebo group (P = 0.001). The safety profiles were similar for both treatment groups except for the higher incidence of gastrointestinal side effects during acarbose therapy. CONCLUSIONS: The addition of acarbose to metformin monotherapy provides an efficacious and safe alternative for glycemic improvement in overweight type 2 patients inadequately controlled by metformin alone.

Acarbose↗
PubMed2003

The type 2 tablet. Evidence based medication for type 2 diabetes.

BACKGROUND: Diabesity--the association of type 2 diabetes and obesity--is a major public health problem worldwide and is increasing dramatically in Australia. The abnormalities associated with diabetes, the 'type 2 diabetes syndrome' are cardiovascular risk factors and increased cardiovascular events. The full implications of type 2 diabetes syndrome may not be fully appreciated and opportunities for effective interventions may be being missed. OBJECTIVE: This article aims to review the cardiovascular risk associated with type 2 diabetes syndrome and to summarise the evidence supporting wider use of medications that target the different components of type 2 diabetes syndrome. DISCUSSION: The cardiovascular benefits of metformin, the ACE inhibitors, aspirin and the statins have been shown in prospective controlled trials and the beneficial effects of these medications are additive. There is a case for these medications to be considered for those with type 2 diabetes (and an opportunity for the pharmaceutical industry to provide the 'type 2 tablet' containing all four medications).

Adult↗