Biomedical subjects

Kevin G Rowley

Publications and source records attributed to Kevin G Rowley.

15 recordsLinked to original sources

PubMed2006

Agreement between laboratory results and on-site pathology testing using Bayer DCA2000+ and Cholestech LDX point-of-care methods in remote Australian Aboriginal communities.

BACKGROUND: Indigenous Australians experience high risk of diabetes and cardiovascular disease. On-site pathology data can help identify those at risk. We sought to evaluate point-of-care (POC) analysers in remote Australian communities. METHODS: Results obtained from population screening (n=76-118) on the DCA2000+ and Cholestech LDX analysers were compared to laboratory measures. Results were compared using parametric and non-parametric statistical analyses, including the use of conventional cut-off values for pathology markers. RESULTS: Agreements (95% CI) between the two methods for categorising results according to the selected cut-off values ranged from 88% (77-94%) for HDL-C to 99% (92-100%) for glucose, and Kappa coefficients ranged from 0.668 for total cholesterol to 0.945 for glucose. Differences in median values were not clinically meaningful but were statistically significant (P<0.05) for urinary albumin (18.8 [inter-quartile range: 7.5-41.7] vs. 18.0 [5.5-43.2] mg/L), creatinine (12.1 [7.9-17.1] vs. 12.4 [8.1-17.0] mmol/L) and albumin:creatinine ratio (ACR; 1.66 [0.70-3.53] vs. 1.27 [0.46-3.03] mg/mmol), HDL cholesterol (HDL-C; 1.05 [0.95-1.25] vs. 1.00 [0.81-1.20] mmol/L), triglycerides (1.65 [1.12-2.19] vs. 1.49 [1.07-2.36] mmol/L) and glucose (5.2 [4.5-6.0] vs. 5.2 [4.7-5.8] mmol/L), respectively, for POC and laboratory methods. Median HbA1c (5.6% [5.3-6.0%] vs. 5.5% [5.3-6.1%]) and total cholesterol (4.4 [3.8-5.0] vs. 4.4 [3.8-5.1] mmol/L) did not differ significantly. Bland-Altman analyses showed statistically significant (but not clinically meaningful) variation in the measurement difference across analyte concentration for all measures except ACR and total cholesterol. CONCLUSION: POC instruments provided a reliable alternative to conventional laboratory methods for screening for chronic disease risk factors in locations remote from urban centres.

Adolescent↗

PubMed2006

Blood pressure and hypertension for Australian Aboriginal and Torres Strait Islander people.

BACKGROUND: Reliable, large-scale, population-based data on blood pressure for Australian Aboriginal and Torres Strait Islander populations are limited. This present study aims to describe the blood pressure levels and to explore the clinical risk factors for hypertension among Australian Aboriginal and Torres Strait Islander peoples. DESIGN: A cross-sectional population survey was conducted in isolated communities in northern and central Australia. METHODS: Australian Aboriginal people (n = 1088) and Torres Strait Islanders (n = 606) aged 15 years and over were examined between 1993 and 1997. Blood pressure, body mass index, plasma glucose and urinary albumin-creatinine ratio were measured. The association of systolic, diastolic and pulse blood pressure to age was determined and independent associations of hypertension with other clinical variables were tested using logistic regression. Comparisons with results from other Australian data (including AusDiab) were made. RESULTS: Systolic blood pressure and pulse pressure increased in a linear manner with age but mean diastolic blood pressure leveled off at around 50 years and decreased thereafter, suggestive of arterial stiffening. The age-standardized prevalence of hypertension (blood pressure > or = 140/90 mmHg or medication) for subjects aged 25-54 years was 27%, compared with 9% in non-Indigenous Australians in the Northern Territory and Queensland (AusDiab Survey). Older age, male sex, higher body mass index, albumin-creatinine ratio and diabetes were independently associated with hypertension. CONCLUSIONS: Elevated blood pressure is a public health concern for indigenous people, which again highlights health differentials in Australia. Early detection and management of high blood pressure should be assigned a high priority in Indigenous communities.

Adolescent↗

PubMed2006

Exercise frequency and arterial compliance in non-diabetic and type 1 diabetic individuals.

BACKGROUND: The role of exercise in preventing cardiovascular disease (CVD) has been well documented. To determine whether this benefit could be related to effects on vascular endothelial function and vessel wall elasticity, thereby preserving arterial compliance, we examined the relationship between habitual exercise and arterial compliance as measured by pulse wave analysis. DESIGN: A cross-sectional study of healthy volunteers and patients with type 1 diabetes. METHODS: Non-diabetic individuals not taking cholesterol or blood pressure-lowering medication (n=176) and patients with type 1 diabetes (n=105), aged 17-70 years, were recruited. Small and large artery compliance and other haemodynamic variables were measured using the PulseWave CR-2000 cardiovascular profiling system. A questionnaire was completed to assess the frequency of physical activity. RESULTS: In multivariate analysis, undertaking three or more episodes of vigorous activity per week was associated with having a 1 unit greater small artery compliance, independent of age, sex, height, diabetes status and blood pressure. The effect was especially marked in non-diabetic women. CONCLUSIONS: The results support other findings that regular physical activity protects against CVD, through the preservation of vascular compliance.

Adolescent↗

PubMed2006

Test agreement for classifying diabetes in indigenous Australians.

OBJECTIVE: To evaluate for Indigenous Australians the agreement between a fasting plasma glucose (FPG) criterion of 7.0 mmol/L and diabetes test results using a two-hour oral glucose tolerance test (OGTT), comparing relationships between test agreement and prevalence to similar studies. METHODS: Screening was undertaken in 25 remote settlements. Agreement between FPG and OGTT results was evaluated using the kappa coefficient (chance-corrected agreement). RESULTS: Participants (n=3,249) ranged from 15-94 years. Kappa ranged from 0.70-0.77 for diabetes prevalence of 5-30%, with overall agreement of 0.76. In comparison studies, the relationship between kappa and diabetes prevalence was similar, but with kappa 0.21-0.48. CONCLUSIONS AND IMPLICATIONS: A FPG test with a 7.0 mmol/L cut-off is a reliable screening method, relative to the OGTT, for remote Indigenous settlements. The level of agreement between the FPG test and the OGTT for the Indigenous population surveyed is superior by far to agreement reported for non-Indigenous samples.

Adult↗

PubMed2005

Leanness and type 2 diabetes in a population of indigenous Australians.

OBJECTIVE: To determine the prevalence of type 2 diabetes and its risk factors in a population of indigenous Australians. RESEARCH DESIGN AND METHODS: A cross-sectional study of 332 indigenous community residents aged 15 years and over with fasting blood samples and anthropometric measurements. RESULTS: Almost half of the study population (47.3%) was extremely lean (BMI<22 kg/m(2)). Leanness was particularly pronounced in the youngest age group (15<20 years), 78% of which had a BMI<22 kg/m(2). The prevalence of diabetes was 12%. It was highest in those 45-54 years and declined in older aged people. No cases of diabetes were detected in those aged less than 30 years. Diabetes prevalence was strongly linked to BMI and age (age-adjusted odds ratio=24.1, 95% CI 6.0-96.5, p<0.001) for BMI>or=25 kg/m(2) versus BMI<22 kg/m(2). Those with the lowest diabetes risk profile are lean (BMI<22 kg/m(2)) and/or young (age 15-34 years). CONCLUSIONS: These results highlight that strategies to prevent or delay the onset of diabetes should focus on the maintenance of leanness from adolescence and throughout adult life whilst young people are still in the process of forming lifelong habits.

Adolescent↗

PubMed2005

Contamination in HPLC quantified benzaldehyde is from polypropylene microtubes.

Semicarbazide-sensitive amine oxidase (SSAO; EC 1.4.3.6) is a copper-containing enzyme predominantly expressed by vascular smooth muscle cells. SSAO deaminates primary amines to produce aldehydes and oxygen peroxides, and may thus play a role in vascular damage. SSAO activity can be quantified by assaying benzaldehyde production using fluorescent derivatisation and separation by HPLC. We performed the derivatisation step in polypropylene or borosilicate glass tubes over 45 min at 95 degrees C. High and obstructing background levels of benzaldehyde were found in one batch of polypropylene vials, as opposed to its alternatives. Treatment and handling of product shipment into the country did not account for introduction of contaminant into packaged vials nor did any reagent used in the assay. We conclude that the source of contamination was most likely due to variation in the commercial production process. Use of borosilicate vials for assays based on aldehyde production and derivatisation is recommended.

Amine Oxidase (Copper-Containing)↗

PubMed2005

Oxidative stress and high-density lipoprotein function in Type I diabetes and end-stage renal disease.

In a cross-sectional study, oxidative stress in high vascular disease risk groups, ESRD (end-stage renal disease) and Type I diabetes, was assessed by measuring plasma protein carbonyls and comparing antioxidant capacity of HDL (high-density lipoprotein) as pertaining to PON1 (paraoxonase 1) activity and in vitro removal of LPO (lipid peroxides). ESRD subjects on haemodialysis (n=22), Type I diabetes subjects (n=20) without vascular complications and healthy subjects (n=23) were compared. Plasma protein carbonyls were higher in ESRD patients [0.16 (0.050) nmol/mg of protein; P=0.001; value is mean (SD)] relative to subjects with Type I diabetes [0.099 (0.014) nmol/mg of protein] and healthy subjects [0.093 (0.014) nmol/mg of protein]. Plasma PON1 activity, with and without correction for HDL-cholesterol, was lower in diabetes but did not differ in ESRD compared with healthy subjects. Plasma PON1 activity, without correction for HDL, did not differ between the three groups. In ESRD, plasma PON1 activity and plasma protein carbonyl concentrations were inversely related (r=-0.50, P<0.05). In an in vitro assay, LPO removal by HDL in ESRD subjects was greater than HDL from healthy subjects (P<0.01), whereas HDL from patients with Type I diabetes was less effective (P<0.01). Efficacy of LPO removal was unrelated to plasma PON1 activity, in vitro glycation or mild oxidation, but was impaired by marked oxidation and glycoxidation. Protein carbonyl levels are increased in ESRD but not in complication-free Type I diabetes. HDL antioxidant function is increased in ESRD, perhaps a compensatory response to increased oxidative stress, but is lower in Type I diabetes. HDL dysfunction is related to glycoxidation rather than glycation or PON1 activity.

Adult↗

PubMed2005

Increases in plasma lycopene concentration after consumption of tomatoes cooked with olive oil.

Lycopene is the main carotenoid in tomatoes and it has been hypothesised to be responsible for reducing the risk of some cancers and heart disease. The cooking of tomatoes with olive oil is a characteristic combination in the Southern Mediterranean diet. Previous studies have shown that the absorption of lycopene is greater from processed tomatoes than fresh tomatoes, since the processing breaks down the tomato cell matrix and makes the lycopene more available. The aim of the present study was to determine whether consumption of diced tomatoes cooked with olive oil resulted in higher plasma lycopene concentrations than consumption of diced tomatoes cooked without olive oil. Plasma lycopene concentrations were measured after 5 days on a low lycopene diet and again after a five-day dietary intervention, in healthy subjects, who consumed one meal per day of tomatoes (470 g) cooked with or without extra virgin olive oil (25 ml olive oil). There was an 82% increase in plasma trans-lycopene (P< 0.001) and a 40% in cis-lycopene (P = 0.002) concentrations in the 11 subjects who consumed tomatoes cooked in olive oil. There was no significant change in trans-lycopene (P = 0.684) and a 15% increase in cis-lycopene (P = 0.007) concentrations in 12 subjects consuming tomatoes cooked without olive oil. We conclude that the addition of olive oil to diced tomatoes during cooking greatly increases the absorption of lycopene. The results highlight the importance of cuisine (i.e how a food is prepared and consumed) in determining the bioavailability of dietary carotenoids such as lycopene.

Adolescent↗

PubMed2003

A cross-sectional study of the effects of type 2 diabetes and other cardiovascular risk factors on structure and function of nonstenotic arteries of the lower limb.

OBJECTIVE: To compare intimal-medial thickness (IMT) and pulse wave conduction velocity (PWCV) in unstenosed arteries of the lower limb in subjects with and without type 2 diabetes and to determine the contribution of a range of cardiovascular risk factors. RESEARCH DESIGN AND METHODS: IMT and PWCV were determined in lower-limb arteries of 79 subjects with diabetes and 77 euglycemic subjects. Plasma lipids were determined by enzymatic assays, and LDL particle size was measured by gradient gel electrophoresis. Lag time for copper-induced oxidation of LDL was determined. alpha-Tocopherol, retinol, and ascorbate levels were determined by high-performance liquid chromatography, soluble E-selectin by enzyme-linked immunosorbent assay, and fibrinogen and factor VII by automated assays. RESULTS: Subjects with diabetes had greater superficial femoral artery (SFA) IMT, popliteal artery (PA) IMT, and SFA PWCV (all P < 0.0001). In univariate analysis, IMT and PWCV correlated with increased waist-to-hip ratio, triglycerides, and fibrinogen and inversely with HDL cholesterol and LDL size. Ascorbate was inversely associated with IMT, and LDL lag time was inversely correlated with PWCV. Subjects with the greatest number of features of the metabolic syndrome had the highest IMT and PWCV. CONCLUSIONS: Adverse changes in the structure and function of unstenosed lower-limb arteries are present in type 2 diabetes and are associated with features of the metabolic syndrome.

Adult↗

PubMed2003

Homocysteine concentrations lowered following dietary intervention in an aboriginal community.

Low circulating folate concentrations lead to elevations of plasma homocysteine. Even mild elevations of plasma homocysteine are associated with significantly increased risk of cardiovascular disease (CVD). Available evidence suggests that poor nutrition contributes to excessive premature CVD mortality in Australian Aboriginal people. The aim of the present study was to examine the effect of a nutrition intervention program conducted in an Aboriginal community on plasma homocysteine concentrations in a community-based cohort. From 1989, a health and nutrition project was developed, implemented and evaluated with the people of a remote Aboriginal community. Plasma homocysteine concentrations were measured in a community-based cohort of 14 men and 21 women screened at baseline, 6 months and 12 months. From baseline to 6 months there was a fall in mean plasma homocysteine of over 2|mol/L (P = 0.006) but no further change thereafter (P = 0.433). These changes were associated with a significant increase in red cell folate concentration from baseline to 6 months (P < 0.001) and a further increase from 6 to 12 months (P < 0.001). In multiple regression analysis, change in homocysteine concentration from baseline to 6 months was predicted by change in red cell folate (P = 0.002) and baseline homocysteine (P < 0.001) concentrations, but not by age, gender or baseline red cell folate concentration. We conclude that modest improvements in dietary quality among populations with poor nutrition (and limited disposable income) can lead to reductions in CVD risk.

Adult↗

PubMed2002

Carotenoids: separation methods applicable to biological samples.

Epidemiologic and clinical studies have shown that a high intake of vegetables and fruit, with consequently high intakes and circulating concentrations of carotenoids, is associated with reduced risk of cardiovascular and other chronic diseases. The antioxidant properties of carotenoids are thought to contribute to these effects. The analysis of carotenoids in plasma, foods and tissues has thus become of interest in studies examining the role of diet in chronic disease prevention and management. High-performance liquid chromatography with ultra-violet or photodiode array detection is most often employed in routine use. We review these and other current methods for carotenoid analysis and information on sample stability relevant to epidemiological studies. The carotenoids remain an important and intriguing subject of study, with relevance to prevention of several important "lifestyle-related" diseases. Research into their physiological functions and their use as dietary markers requires sensitive, accurate and precise measurement. Further advances in these methodological areas will contribute to basic, clinical and public health research into the significance of carotenoid compounds in disease prevention.

Carotenoids↗

PubMed2002

Fasting criteria for screening: test properties and agreement with glucose tolerance.

The objective of this study was to characterise test properties and agreement for fasting glucose cut-offs used for screening diabetes in Indigenous Australian communities, across a range of diabetes prevalence. The oral glucose tolerance test (OGTT) was administered to adult volunteers (n=3249) for community-based diabetes screening in isolated settlements (n=25). Two-hour post-load glucose concentration was the 'gold standard' against which test properties were characterised for fasting plasma glucose cut-offs at concentrations of > or = 7.0 mmol/l (ADA criterion) and > or = 7.8 mmol/l (WHO criterion). Test sensitivity (95% CI) was greater for the ADA (72.5%, 67.4-77.1%) versus the WHO criterion (61.5%, 56.1-66.6%). Specificity was high (>98%) using either criterion. The post-test likelihood of diabetes, given a population prevalence of 14.8%, was 89.1% using the ADA criterion, and 94.9% using the WHO criterion. The ADA criterion gave better agreement than did the WHO criterion for diabetes prevalence > or = 8.6%, and the probability of false results was lower using the ADA criterion, when diabetes prevalence was > or = 12.8%. According to the ADA criterion most individuals ascribed false negative results were aged > or = 35 years, overweight/obese, or had impaired fasting glucose. The fasting glucose criterion of 7.0 mmol/l was superior to 7.8 mmol/l in screening for diabetes.

Adolescent↗

PubMed2002

Obesity, diabetes and associated cardiovascular risk factors among Torres Strait Islander people.

OBJECTIVE: To describe the lifestyle-related chronic disease and risk factor prevalence among Torres Strait Islander people of the Torres Strait and Northern Peninsula Area Health Service District and to compare this information with that available for the general Australian population. METHODS: Voluntary community-based screening for persons aged 15 years and older, including oral glucose tolerance test, anthropometry, health questionnaire, measurement of lipids and lipoprotein levels, blood pressure and urinary albumin to creatinine ratio. RESULTS: Nine communities participated in screening between 1993 and 1997. Five hundred and ninety-two participants (286 male and 306 female) identified as Torres Strait Islander. There were high prevalences of overweight (30%), obesity (51%), abdominal obesity (70%), diabetes (26%), hypercholesterolaemia (33%), albuminuria (28%), hypertension (32%) and tobacco smoking (45%). Only 8.5% of men and 6.5% of women were free of any cardiovascular risk factors (abdominal obesity, hypercholesterolaemia, hypertension, dyslipidaemia, smoking, diabetes, albuminuria). Comparisons of this information for Torres Strait Islander people with results from the AusDiab survey show rates of obesity three times higher and diabetes six times higher than for other Australians. CONCLUSIONS: There is a very high prevalence of preventable chronic disease and associated risk factors among Torres Strait Islander people of the Torres Strait and Northern Peninsula Area. IMPLICATIONS: Effective interventions to prevent and manage obesity, diabetes and associated cardiovascular risk factors are essential if the health of the Torres Strait Islander people is to improve. Such interventions could inform initiatives to stem the burgeoning epidemic of obesity and diabetes among all Australians.

Anthropometry↗

PubMed2002

Paraoxonase and other coronary risk factors in a community-based cohort.

Oxidative damage to circulating lipids and vascular tissues contributes to the initiation and progression of atherosclerosis. High density lipoprotein provides protection from atherosclerosis and the enzyme paraoxonase may contribute to this effect. The aim of the present study was to examine the trends in paraoxonase activity during the course of a community-directed life-style intervention, and relationships of paraoxonase activity to other coronary heart disease risk factors, in a cohort of Australian Aboriginal people.

Adolescent↗

PubMedDate not supplied

Macrovascular disease risk factors and insulin resistance in Aboriginal and Torres Strait Islander people.

It has been proposed that insulin resistance (IR) underlies a cluster of cardiovascular disease (CVD) risk factors constituting a "metabolic syndrome." CVD is a leading cause of premature mortality among indigenous Australians. In a group of younger (15-44 years, fasting glucose <7.8 mmol/l) Aboriginal (n=643) and Torres Strait Islander (n=220) people participating in community-based risk factor surveys, we identified high prevalences of metabolic syndrome components: glucose intolerance, dyslipidaemia, hypertension, and IR. There were inconsistent associations of IR with other risk factors, and the data do not support a direct causal relationship between insulin and other metabolic variables. Rather, metabolic syndrome components may arise from social and environmental factors interacting with behavioural and biochemical factors in individuals.

Adolescent↗