Clinical Trial Service Unit

About: Clinical Trial Service Unit is a based out in . It is known for research contribution in the topics: Population & Stroke. The organization has 428 authors who have published 1387 publications receiving 181920 citations.

Analysis of ant foraging algorithms

Abstract: We consider some models of ant foraging and recruitment behaviour that depend on each individual ant following a simple algorithm. Self-organisation enables the colony as a whole to establish a foraging strategy in the absence of any hierarchical control. In this paper we investigate how the effectiveness of such a foraging strategy depends on the persistence of the signals used by the individual ants and on the errors they make in following such signals. The use of inhibitory as well as excitatory signals is considered, and shown to be extremely effective in certain circumstances. This is interesting, as such signals have never been observed in real ant colonies. Such models are often investigated by simulation, but we approach them from the point of view of statistical mechanics. Looked at another way, which yields some insight, we approximate the stochastic process that models the system by a diffusion process with small diffusion parameter. This approach does not replace simulation, but supplements it. Its advantage is that it can elucidate the role of parameters more clearly and using much less computer time than simulation, but its disadvantage is that many simplifying assumptions must be made before the problem is amenable to analytic treatment.

Cystatin C and risk of vascular and nonvascular mortality: a prospective cohort study of older men

Abstract: . Emberson JR, Haynes R, Dasgupta T, Mafham M, Landray MJ, Baigent C, Clarke R (University of Oxford, Oxford, UK). Cystatin C and risk of vascular and nonvascular mortality: a prospective cohort study of older men. J Intern Med 2010; 268: 145–154. Objective. To assess the relevance of cystatin C, as a marker of mild-to-moderate renal impairment, for vascular and nonvascular mortality in older people. Design. Prospective cohort study. Setting. Re-survey in 1997 to 1998 of survivors in the 1970 Whitehall study of London civil servants. Subjects. Five thousand three hundred and seventy-one men (mean age at resurvey: 77 years) who took part in the resurvey and had plasma cystatin C concentration measured. Main outcome measures. Cause-specific mortality over subsequent 11 years (1997 to 2008). Methods. Cox regression was used to estimate the associations of cystatin C with vascular and nonvascular mortality, before and after adjustment for prior disease and other risk factors (including lifetime blood pressure). Results. During an 11.0-year follow-up period, there were 1171 deaths from vascular causes [26 per 1000 per year (py)] and 1615 deaths from nonvascular causes (36 per 1000 py). Compared with men with cystatin C in the bottom fifth of the distribution, men in the top 10th had about two-fold higher mortality rates from vascular and nonvascular mortality (fully adjusted P both <0.001) even after adjustment for prior disease and all measured confounders, including lifetime blood pressure. The fully adjusted relative risks per 50% higher cystatin C concentrations were 1.66 [95% CI 1.48 to 1.85] for vascular mortality, 1.92 [95% CI 1.66 to 2.22] for ischaemic heart disease mortality and 1.46 [95% CI 1.31 to 1.61] for nonvascular mortality. Conclusions. In older men, plasma concentration of cystatin C, probably as a marker of mild renal disease, is a strong independent predictor of both vascular and nonvascular mortality.

Utility of single versus sequential measurements of risk factors for prediction of stroke in Chinese adults.

Abstract: Absolute risks of stroke are typically estimated using measurements of cardiovascular disease risk factors recorded at a single visit. However, the comparative utility of single versus sequential risk factor measurements for stroke prediction is unclear. Risk factors were recorded on three separate visits on 13,753 individuals in the prospective China Kadoorie Biobank. All participants were stroke-free at baseline (2004–2008), first resurvey (2008), and second resurvey (2013–2014), and were followed-up for incident cases of first stroke in the 3 years following the second resurvey. To reflect the models currently used in clinical practice, sex-specific Cox models were developed to estimate 3-year risks of stroke using single measurements recorded at second resurvey and were retrospectively applied to risk factor data from previous visits. Temporal trends in the Cox-generated risk estimates from 2004 to 2014 were analyzed using linear mixed effects models. To assess the value of more flexible machine learning approaches and the incorporation of longitudinal data, we developed gradient boosted tree (GBT) models for 3-year prediction of stroke using both single measurements and sequential measurements of risk factor inputs. Overall, Cox-generated estimates for 3-year stroke risk increased by 0.3% per annum in men and 0.2% per annum in women, but varied substantially between individuals. The risk estimates at second resurvey were highly correlated with the annual increase of risk for each individual (men: r = 0.91, women: r = 0.89), and performance of the longitudinal GBT models was comparable with both Cox and GBT models that considered measurements from only a single visit (AUCs: 0.779–0.811 in men, 0.724–0.756 in women). These results provide support for current clinical guidelines, which recommend using risk factor measurements recorded at a single visit for stroke prediction.

Circulating isoflavone and lignan concentrations and prostate cancer risk: a meta-analysis of individual participant data from seven prospective studies including 2,828 cases and 5,593 controls.

Abstract: Phytoestrogens may influence prostate cancer development. This study aimed to examine the association between prediagnostic circulating concentrations of isoflavones (genistein, daidzein, equol) and lignans (enterolactone and enterodiol) and the risk of prostate cancer. Individual participant data were available from seven prospective studies (two studies from Japan with 241 cases and 503 controls and five studies from Europe with 2,828 cases and 5,593 controls). Because of the large difference in circulating isoflavone concentrations between Japan and Europe, analyses of the associations of isoflavone concentrations and prostate cancer risk were evaluated separately. Prostate cancer risk by study-specific fourths of circulating concentrations of each phytoestrogen was estimated using multivariable-adjusted conditional logistic regression. In men from Japan, those with high compared to low circulating equol concentrations had a lower risk of prostate cancer (multivariable-adjusted OR for upper quartile [Q4] vs. Q1 = 0.61, 95% confidence interval [CI] = 0.39–0.97), although there was no significant trend (OR per 75 percentile increase = 0.69, 95 CI = 0.46–1.05, ptrend = 0.085); Genistein and daidzein concentrations were not significantly associated with risk (ORs for Q4 vs. Q1 = 0.70, 0.45–1.10 and 0.71, 0.45–1.12, respectively). In men from Europe, circulating concentrations of genistein, daidzein and equol were not associated with risk. Circulating lignan concentrations were not associated with the risk of prostate cancer, overall or by disease aggressiveness or time to diagnosis. There was no strong evidence that prediagnostic circulating concentrations of isoflavones or lignans are associated with prostate cancer risk, although further research is warranted in populations where isoflavone intakes are high.