Moisture, anisotropy, stress state, and strain rate effects on bighorn sheep horn keratin mechanical properties.

This paper investigates the effects of moisture, anisotropy, stress state, and strain rate on the mechanical properties of the bighorn sheep (Ovis Canadensis) horn keratin. The horns consist of fibrous keratin tubules extending along the length of the horn and are contained within an amorphous keratin matrix. Samples were tested in the rehydrated (35wt% water) and ambient dry (10wt% water) conditions along the longitudinal and radial directions under tension and compression. Increased moisture content was found to increase ductility and decrease strength, as well as alter the stress state dependent nature of the material. The horn keratin demonstrates a significant strain rate dependence in both tension and compression, and also showed increased energy absorption in the hydrated condition at high strain rates when compared to quasi-static data, with increases of 114% in tension and 192% in compression. Compressive failure occurred by lamellar buckling in the longitudinal orientation followed by shear delamination. Tensile failure in the longitudinal orientation occurred by lamellar delamination combined with tubule pullout and fracture. The structure-property relationships quantified here for bighorn sheep horn keratin can be used to help validate finite element simulations of ram's impacting each other as well as being useful for other analysis regarding horn keratin on other animals. STATEMENT OF SIGNIFICANCE: The horn of the bighorn sheep is an anisotropic composite composed of keratin that is highly sensitive to moisture content. Keratin is also found in many other animals in the form of hooves, claws, beaks, and feathers. Only one previous study contains high rate experimental data, which was performed in the dry condition and only in compression. Considering the bighorn sheep horns' protective role in high speed impacts along with the moisture and strain rate sensitivity, more high strain rate data is needed to fully characterize and model the material. This study provides high strain rate results demonstrating the effects of moisture, anisotropy, and stress state. As a result, the comprehensive data allows modeling efforts to be greatly improved.

Diabetic foot complications among patients attending a specialist diabetes clinic in Jamaica: prevalence and associated factors.

OBJECTIVES: To estimate the prevalence of diabetic foot complications among patients at a specialist diabetes clinic in Jamaica and identify factors associated with foot complications. METHODS: A stratified random sample of 188 patients were interviewed and examined between 2009 and 2010. Trained nurses obtained demographic and clinical data, measured anthropometrics and performedfoot examinations including inspection for amputations, ulcers or infection and assessment of pain, vibration and pressure perception. RESULTS: Participants included 143 women and 45 men (mean age 56years; mean diabetes duration 16 years). The prevalence of amputations was 8.5% (95% CI 4.5, 12.5%) and was higher among men (22.2%) compared to women (4.2%, p < 0.05). Prevalence of current ulcers and current foot infections was 4.3% and 3.7%, respectively. Overall, 12% ofpatients had at least one of these foot complications. Foot complications were more prevalent among men, patients with high blood pressure (BP > or = 130/80 mmHg) or peripheral neuropathy In multivariable logistic regression models, factors associated with foot complications were: neuropathy (OR 9.3 [95% CI 2.8, 30.3]), high BP (OR 7.9 [1.3, 49.7]) and diabetes duration (OR 1.32 [1.02, 1.72]). CONCLUSION: Approximately one of every eight patients in this specialist clinic had a major foot complication. Associated factors were neuropathy, high blood pressure and longer duration of diabetes.

Prevalence of high-risk sexual behaviour in Jamaican adults and its relationship to sociodemographic and religious factors: findings from the Jamaica Health and Lifestyle Survey 2007-2008.

OBJECTIVE: To estimate the prevalence of high-risk sexual behaviours among Jamaican adults and evaluate associations with sociodemographic and religious factors. METHODS: We performed a cross-sectional study, using a nationally representative sample of Jamaicans, 15-74 years old. Participants completed an interviewer-administered questionnaire including questions on sexual activity, sociodemographic factors and religious practice. Having two or more sexual partners in the past year, non-use of condoms among persons with multiple partners and a history of previous sexually transmitted infection (STI) were the high-risk characteristics considered in the analysis. We obtained crude and category specific prevalence estimates for high-risk behaviour and estimated odds ratios for association with sociodemographic and religious factors. RESULTS: Data from 2833 participants who reported on sexually activity were analysed. Approximately 25% (95% CI 22, 27) of Jamaican adults had two or more sexual partners in the past year while 15% (95% CI 13, 17) had a past history of an STI. Approximately 6% (95% CI 5, 7) of persons with multiple partners did not use condoms during sexual intercourse. Overall, 32% (95% CI 30, 35) had any one of the three high-risk characteristics (male, 48%; female, 17%, p < 0.001). Being married, active religious practice and weekly attendance at religious meetings were associated with lower odds of high-risk sexual behaviour while being in a visiting relationship was associated with higher odds of high-risk behaviour CONCLUSION: A third of Jamaicans reported sexual practices that increase their risk of HIV infection. High-risk sexual behaviour was more common among men. Being married and weekly attendance at religious services were associated with lower odds of high-risk behaviour

An update on the burden of cardiovascular disease risk factors in Jamaica: findings from the Jamaica Health and Lifestyle Survey 2007-2008.

BACKGROUND: Previous studies have documented a high burden of cardiovascular disease (CVD) risk factors in Jamaica and suggest that mortality from CVD may be increasing. This paper provides an update on the burden of CVD risk factors in Jamaica using data from the most recent national health survey and evaluates the impact of obesity and physical activity on other CVD risk factors. METHODS: The Jamaica Health and Lifestyle Survey 2007-2008 (JHLS-2) recruited a nationally representative sample of 2848 Jamaicans, 15-74 years old between November 2007 and March 2008. An interviewer administered questionnaire was used to obtain data on demographic characteristics, medical history and health behaviour Blood pressure and anthropometric measurements were made using standardized protocols and capillary blood samples were obtained to measure fasting glucose and total cholesterol. Prevalence estimates for the various CVD risk factors were obtained within and across sex and other demographic categories. Data were weighted for the complex survey design, nonresponse to questionnaire items or failure to complete some segments of the evaluation. RESULTS: Prevalence estimates for traditional CVD risk factors were: hypertension, 25%; diabetes, 8%; hypercholesterolaemia, 12%; obesity, 25%; smoking 15%. In addition, 35% of Jamaicans had prehypertension, 3% had impaired fasting glucose and 27% were overweight. A higher proportion of women had diabetes, obesity and hypercholesterolaemia while the prevalence of prehypertension and cigarette smoking was higher in men. Approximately 50% of persons with hypertension, 25% of persons with diabetes and 86% of persons with hypercholesterolaemia were unaware of their risk status. In multivariate analysis, obesity was associated with increased odds of hypertension, diabetes and hypercholesterolaemia while physical inactivity was associated with higher odds of diabetes. CONCLUSION: The burden of CVD risk factors in Jamaica remains very high and warrants interventions to reduce CVD risk.

Prehypertension in Jamaica: a review of data from recent studies.

Prehypertension is defined as a systolic blood pressure of 120-139 mmHg or diastolic blood pressure of 80-89 mmHg in patients not on medication for hypertension. Recent studies have shown that prehypertension has a high prevalence in both western and eastern countries and is associated with cardiovascular disease (CVD) risk factors, incident CVD and CVD mortality. We reviewed data from ongoing epidemiological studies in Jamaica in order to provide an update on the prevalence and predictors of prehypertension in Jamaica. Studies included were the Jamaica Health and Lifestyle Surveys (2000-2001 and 2007-2008), the Jamaica Youth Risk and Resiliency Behaviour Survey 2006, the 1986 Jamaica Birth Cohort Study and the Spanish Town Cohort Study. The prevalence of prehypertension in the most recent national survey was 35% (95% CI 33, 38%). Prevalence was higher in men compared to women (42% versus 29%). Jamaicans with prehypertension were more likely to have other CVD risk factors and were three times more likely to develop hypertension compared with persons with a normal blood pressure. Prevalence was also high among youth, particularly males. Longitudinal analysis from the 1986 birth cohort suggested that prehypertension may be more common in persons with low birthweight or short birth length. Physicians and public health practitioners should recognize the increased CVD risk associated with prehypertension and should begin to institute CVD prevention measures in persons with prehypertension. Sex differences and the early onset of prehypertension in men require further exploration.