Publications by authors named "John B Prins"

8 Publications

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Diabetes screen during tuberculosis contact investigations highlights opportunity for new diabetes diagnosis and reveals metabolic differences between ethnic groups.

Tuberculosis (Edinb) 2018 12 18;113:10-18. Epub 2018 Aug 18.

DST-NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa; Mater Research Institute - The University of Queensland, Translational Research Institute, Brisbane, QLD, Australia. Electronic address:

Type 2 diabetes (T2D) is a prevalent risk factor for tuberculosis (TB), but most studies on TB-T2D have focused on TB patients, been limited to one community, and shown a variable impact of T2D on TB risk or treatment outcomes. We conducted a cross-sectional assessment of sociodemographic and metabolic factors in adult TB contacts with T2D (versus no T2D), from the Texas-Mexico border to study Hispanics, and in Cape Town to study South African Coloured ethnicities. The prevalence of T2D was 30.2% in Texas-Mexico and 17.4% in South Africa, with new diagnosis in 34.4% and 43.9%, respectively. Contacts with T2D differed between ethnicities, with higher smoking, hormonal contraceptive use and cholesterol levels in South Africa, and higher obesity in Texas-Mexico (p < 0.05). PCA analysis revealed striking differences between ethnicities in the relationships between factors defining T2D and dyslipidemias. Our findings suggest that screening for new T2D in adult TB contacts is effective to identify new T2D patients at risk for TB. Furthermore, studies aimed at predicting individual TB risk in T2D patients, should take into account the heterogeneity in dyslipidemias that are likely to modify the estimates of TB risk or adverse treatment outcomes that are generally attributed to T2D alone.
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http://dx.doi.org/10.1016/j.tube.2018.08.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6284235PMC
December 2018

Osteoporosis-Related Health Behaviors in Men With Prostate Cancer and Survivors: Exploring Osteoporosis Knowledge, Health Beliefs, and Self-Efficacy.

Am J Mens Health 2017 Jan 23;11(1):13-23. Epub 2016 Jun 23.

1 Centre for Dietetics Research, School of Human Movement and Nutrition Sciences,The University of Queensland, Australia.

This descriptive study aimed to (a) determine the extent of osteoporosis knowledge, perceived health beliefs, and self-efficacy with bone healthy behaviors in men with prostate cancer and survivors and (b) identify how dietary bone healthy behaviors are associated with these psychobehavioral and psychosocial factors. Three different questionnaires were used to measure osteoporosis knowledge, health beliefs, and self-efficacy in a group of men with prostate cancer and survivors. Bone health was assessed via dual-energy X-ray absorptiometry and calcium intake using a diet history. The prevalence of osteoporosis and low bone mass was high at over 70%. Participants had inadequate osteoporosis knowledge with a mean score of 43.3% ( SD = 18%) on the Facts on Osteoporosis Quiz. Participants scored low on the subscale measuring barriers to exercise (median = 11; interquartile range [IQR] = 6.5), indicating minimal barriers to exercise participation, and the subscale measuring the benefits of exercise scored the highest (median = 24; IQR = 3.5) compared with the other subscales. Men with prostate cancer and survivors were highly confident in their exercise and calcium self-efficacy (83.0%, IQR = 24.0% and 85.7%, IQR = 27.0%, respectively). Participants did not meet their calcium requirements or consume enough dairy products for optimum bone health. Men with prostate cancer and survivors have poor osteoporosis knowledge, but are confident in their self-efficacy of undertaking bone healthy behaviors. This confidence did not translate to specific dietary behaviors as they did not meet their calcium or dairy intake requirements. Implications for cancer survivors is that there is a need for bone health education programs among prostate cancer survivors. These programs should go beyond education and empowerment to provide practical guidance to maximize uptake of bone healthy behaviors.
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http://dx.doi.org/10.1177/1557988315615956DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5675183PMC
January 2017

Prevalence of osteoporosis in prostate cancer survivors II: a meta-analysis of men not on androgen deprivation therapy.

Endocrine 2015 Nov 31;50(2):344-54. Epub 2015 Jan 31.

Centre for Dietetics Research (C-DIET-R), School of Human Movement and Nutrition Science, The University of Queensland, St Lucia, QLD, 4072, Australia.

The prevalence of osteoporosis in men with prostate cancer (PCa) on androgen deprivation therapy (ADT) is well documented, with up to 53% affected by this bone condition. However, there has been less emphasis on the burden of severe bone loss in men with PCa but not undergoing ADT. Therefore, the purpose of this meta-analysis is to compile evidence from the literature on the bone health of hormone-naïve PCa patients and to compare it to the bone health of men with PCa on ADT. Three databases were searched for the relevant literature published from 1990 until January 2014. The pooled prevalence of osteoporosis, low bone mass, and normal bone mass were estimated for this patient group and compared with similar subgroups from a previously published meta-analysis. The prevalence of osteoporosis varies from 4 to 38% in hormone-naïve PCa patients, and men with more advanced disease have a higher prevalence of osteoporosis. Men with PCa on ADT have poorer bone health than their hormone-naïve counterparts, but the trend toward poorer bone health with metastatic disease remains. In conclusion, it was found that men with PCa experience poor bone health prior to treatment with ADT. These results suggest that all men with PCa should have regular bone health monitoring, whether they commence ADT or not, in order to prevent or indeed minimize the morbidity that accompanies osteoporosis.
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http://dx.doi.org/10.1007/s12020-015-0536-7DOI Listing
November 2015

Prevalence of osteoporosis in prostate cancer survivors: a meta-analysis.

Endocrine 2014 Apr 31;45(3):370-81. Epub 2013 Oct 31.

Centre for Dietetics Research (C-DIET-R), School of Human Movement Studies, The University of Queensland, St Lucia, QLD, 4072, Australia,

Androgen deprivation therapy (ADT), which is used in the treatment of prostate cancer (PCa), is associated with increased morbidity. Severe bone loss is a major consequence of androgen ablation and with an increasing number of patients undergoing this treatment, the incidence of osteoporosis and fractures can be expected to increase with a significant impact on healthcare. To evaluate the prevalence of osteoporosis, we conducted a review of the literature on bone health in men with PCa undergoing ADT. A meta-analysis was conducted using the quality effects model, and sources of heterogeneity were further explored by consideration of discordant effect sizes of included studies in the meta-analysis and examining reasons thereof. Our analyses indicate that the prevalence of osteoporosis varies between 9 and 53 % with this variation partially explained by treatment duration, disease stage, ethnicity and site of osteoporosis measurement. While it is well known that a rapid decline in bone health amongst men with PCa on ADT occurs, this meta-analysis documents the high prevalence of osteoporosis in this population and reinforces the need of preventative approaches as part of usual care of PCa patients.
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http://dx.doi.org/10.1007/s12020-013-0083-zDOI Listing
April 2014

Sialic acid modification of adiponectin is not required for multimerization or secretion but determines half-life in circulation.

Mol Endocrinol 2010 Jan 23;24(1):229-39. Epub 2009 Oct 23.

Diamantina Institute for Cancer, Immunology and Metabolic Medicine, University of Queensland, Brisbane, Queensland, Australia.

Adiponectin is an adipocyte-secreted, insulin-sensitizing hormone the circulating levels of which are reduced in conditions of insulin resistance and diabetes. Previous work has demonstrated the importance of posttranslational modifications, such as proline hydroxylation and lysine hydroxylation/glycosylation, in adiponectin oligomerization, secretion, and function. Here we describe the first functional characterization of adiponectin sialylation. Using a variety of biochemical approaches we demonstrated that sialylation occurs on previously unidentified O-linked glycans on Thr residues of the variable domain in human adiponectin. Enzymatic removal of sialic acid or its underlying O-linked sugars did not affect adiponectin multimer composition. Expression of mutant forms of adiponectin (lacking the modified Thr residues) or of wild-type adiponectin in cells defective in sialylation did not compromise multimer formation or secretion, arguing against a structural role for this modification. Activity of desialylated adiponectin was comparable to control adiponectin in L6 myotubes and acute assays in adiponectin(-/-) mice. In contrast, plasma clearance of desialylated adiponectin was accelerated compared with that of control adiponectin, implicating a role for this modification in determining the half-life of circulating adiponectin. Uptake of desialylated adiponectin by isolated primary rat hepatocytes was also accelerated, suggesting a role for the hepatic asialoglycoprotein receptor. Finally, after chronic administration in adiponectin(-/-) mice steady-state levels of desialylated adiponectin were lower than control adiponectin and failed to recapitulate the improvements in glucose and insulin tolerance tests observed with control adiponectin. These data suggest an important role for sialic acid content in the regulation of circulating adiponectin levels and highlight the importance of understanding mechanisms regulating adiponectin sialylation/desialylation.
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http://dx.doi.org/10.1210/me.2009-0133DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5428139PMC
January 2010

Adiponectin is associated with cardiovascular disease in male renal transplant recipients: baseline results from the LANDMARK 2 study.

BMC Nephrol 2009 Oct 12;10:29. Epub 2009 Oct 12.

Department of Nephrology Princess Alexandra Hospital, Brisbane, Queensland, Australia.

Background: Adiponectin is a major adipocyte-derived protein with insulin-sensitizing, anti-inflammatory and anti-atherogenic properties. Adiponectin levels correlate inversely with renal function and higher levels are predictive of lower cardiovascular disease (CVD) in patients with normal renal function and chronic kidney disease. No data exists on the association between adiponectin and CVD in renal transplant recipients (RTR).

Methods: Standard biochemistry, clinical data and adiponectin were collected from 137 RTR recruited to the LANDMARK 2 study at baseline. The LANDMARK 2 study is an ongoing randomized controlled study that compares the outcome of aggressive risk factor modification for cardiovascular disease versus standard post-transplant care in renal transplant recipients with impaired glucose tolerance or diabetes mellitus.

Results: Mean patient age was 53.4 +/- 12 years and the median post-transplantation period was 5 (0.5-31.9) years. Mean serum adiponectin level was 12.3 +/- 7.1 microg/mL. On univariate analysis, adiponectin was positively associated with female gender (P = 0.01) and serum high-density lipoprotein (HDL) concentration (P < 0.001), and inversely with body mass index (P = 0.009), metabolic syndrome (P = 0.047), abnormal glucose tolerance (P = 0.01), C-reactive protein (P = 0.001) and serum triglyceride (P < 0.001). On stepwise multivariate analysis, adiponectin in males was negatively correlated with combined baseline CVD (P = 0.03), waist-hip ratio (P = 0.003) and glomerular filtration rate (P = 0.046), and positively with HDL (P < 0.001). In contrast, in females adiponectin was inversely associated with C-reactive protein (P = 0.001) and serum triglyceride.

Conclusion: In conclusion, adiponectin is positively correlated with inflammation, dyslipidemia and abnormal glucose tolerance in RTR. Furthermore, hypoadiponectinemia correlated with increased baseline CVD in male RTR.
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http://dx.doi.org/10.1186/1471-2369-10-29DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2766377PMC
October 2009

Insulin levels in insulin resistance: phantom of the metabolic opera?

Med J Aust 2006 Aug;185(3):159-61

Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, New South Wales.

Insulin resistance is considered a core component in the pathophysiology of the metabolic syndrome. Some clinicians measure serum insulin concentrations in the mistaken belief that they can be used to diagnose insulin resistance. Serum insulin levels are poor measures of insulin resistance. Furthermore, there is no clinical benefit in measuring insulin resistance in clinical practice. Measurements of fasting serum insulin levels should be reserved for large population-based epidemiological studies, where they can provide valuable data on the relationship of insulin sensitivity to risk factors for diabetes and cardiovascular disease. Clinicians should shift from identifying "insulin resistance" to identifying risk factors, such as fasting glucose and lipid levels, hypertension and central obesity. These proven risk factors converge within the metabolic syndrome. Individuals "at risk" of diabetes and atherosclerotic cardiac disease can be identified simply and inexpensively, using classic clinical techniques, such as history-taking, physical examination, and very basic investigations.
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http://dx.doi.org/10.5694/j.1326-5377.2006.tb00506.xDOI Listing
August 2006

Body mass index-related human adipocyte agouti expression is sex-specific but not depot-specific.

Obes Res 2002 Jun;10(6):447-52

Cooperative Research Centre for Diagnostic Technologies, Queensland University of Technology, Brisbane, Australia.

Objective: To determine if human adipocyte agouti signal protein (ASIP) mRNA expression is associated with obesity and is gender and/or depot specific.

Research Methods And Procedures: Subjects included 8 men (64 +/- 3 years) and 14 women (56 +/- 15 years) undergoing elective abdominal surgery. ASIP mRNA levels in isolated omental and subcutaneous abdominal adipocytes were measured by quantitative reverse transcription polymerase chain reaction.

Results: No significant depot difference was observed between genders; ASIP mRNA levels of omental and subcutaneous abdominal adipocytes were pooled for this analysis. BMI and ASIP gene expression were negatively correlated in men (rho = -0.70; p < 0.05), whereas a positive relationship was observed in women (rho = 0.48; p < 0.05). No significant difference was observed in age, body weight, body mass index (BMI), and waist circumference between groups. Hip circumference was significantly higher in women than in men (p < 0.05). Also, no significant difference in ASIP mRNA expression was observed between men and women, regardless of the fat depot.

Discussion: These results show that men and women of similar age and BMI present similar ASIP mRNA levels in omental and subcutaneous abdominal adipocytes. However, a sexual dimorphism exists in the relationship between ASIP expression and BMI. If ASIP is involved in appetite regulation or energy homeostasis in humans, this observation may contribute to the recognized differences in these parameters between men and women.
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http://dx.doi.org/10.1038/oby.2002.62DOI Listing
June 2002