Robust inference for non-linear regression models from the Tsallis score: Application to coronavirus disease 2019 contagion in Italy.

We discuss an approach of robust fitting on non-linear regression models, in both frequentist and Bayesian approaches, which can be employed to model and predict the contagion dynamics of the coronavirus disease 2019 (COVID-19) in Italy. The focus is on the analysis of epidemic data using robust dose-response curves, but the functionality is applicable to arbitrary non-linear regression models.

Kidney size in relation to ageing, gender, renal function, birthweight and chronic kidney disease risk factors in a general population.

BACKGROUND: The relationship of kidney size to ageing, kidney function and kidney disease risk factors is not fully understood. METHODS: Ultrasound length and parenchymal kidney volume were determined from a population-based sample of 3972 Sardinians (age range 18-100 years). We then identified the subset of 2256 'healthy' subjects to define age- and sex-specific reference ranges (2.5-97.5 percentile) of kidney volume. Logistic regression (accounting for family clustering) was used to identify the clinical characteristics associated with abnormally large kidneys or abnormally small kidneys. RESULTS: In the healthy subset, kidney volume and length increased up to the fourth to fifth decade of life followed by a progressive decrease in men, whereas there was a gradual kidney volume decrease throughout the lifespan of women. In the whole sample, independent predictors of lower kidney volume (<2.5 percentile for age and sex) were male sex, low body mass index, short height, low waist:hip ratio and high serum creatinine (SCr); the independent predictors of larger kidney volume (>97.5 percentile for age and sex) were younger age, female sex, diabetes, obesity, high height, high waist:hip ratio and lower SCr. Estimated heritability for kidney volume was 15%, and for length 27%; kidney volume correlated strongly with birthweight. CONCLUSIONS: Overall, in a general healthy population, kidney measures declined with age differently in men and women. The determinants of kidney parenchymal volume include genetic factors and modifiable clinical factors.

Unscaled Bayes factors for multiple hypothesis testing in microarray experiments.

Multiple hypothesis testing collects a series of techniques usually based on p-values as a summary of the available evidence from many statistical tests. In hypothesis testing, under a Bayesian perspective, the evidence for a specified hypothesis against an alternative, conditionally on data, is given by the Bayes factor. In this study, we approach multiple hypothesis testing based on both Bayes factors and p-values, regarding multiple hypothesis testing as a multiple model selection problem. To obtain the Bayes factors we assume default priors that are typically improper. In this case, the Bayes factor is usually undetermined due to the ratio of prior pseudo-constants. We show that ignoring prior pseudo-constants leads to unscaled Bayes factor which do not invalidate the inferential procedure in multiple hypothesis testing, because they are used within a comparative scheme. In fact, using partial information from the p-values, we are able to approximate the sampling null distribution of the unscaled Bayes factor and use it within Efron's multiple testing procedure. The simulation study suggests that under normal sampling model and even with small sample sizes, our approach provides false positive and false negative proportions that are less than other common multiple hypothesis testing approaches based only on p-values. The proposed procedure is illustrated in two simulation studies, and the advantages of its use are showed in the analysis of two microarray experiments.

Cognitive decline and depressive symptoms in late-life are associated with statin use: evidence from a population-based study of Sardinian old people living in their own home.

OBJECTIVES: This study was designed to provide further insights into the effects of dyslipidemia (Dys-y) and use of statins (St-y) on cognitive functions and mood in older people. METHODS: Three hundred and twenty-nine subjects aged > or = 65 years were screened for cognitive dysfunction using mini mental state examination (MMSE). The geriatric depression scale (GDS) was used to detect depression. Interview questionnaires surveyed activities of daily living (ADL) and instrumental ADL (IADL), as well as other functional disabilities. The presence of neutral lipids (NLs) in cytoplasm of peripheral blood mononuclear cells (PBMCs) was determined with the Oil red O (ORO) staining. RESULTS: There was no significant difference in MMSE and GDS scores between normal (Dys-n) and Dys-y. However, when Dys-y subjects were divided into St-y and non-statin users (St-n), significant differences emerged in the scores of MMSE and GDS: St-y had lower MMSE and higher GDS than St-n. Multiple correspondence analysis and logistic regression provided further evidence that elderly St-y were much more likely to suffer of cognitive impairment and depression than St-n. Another interesting finding was that the intensity of NL-PBMCs measured by ORO staining was greater in subjects with altered MMSE compared with cognitively normal subjects. In addition St-y had higher ORO score than St-n. DISCUSSION: This is an observational study and cannot, therefore, prove a causal relationship between St-y in the elderly and a higher cognitive decline, nevertheless it provides substantial indications that caution should be exercised in the provision of statins in elderly subjects to avoid accelerated memory loss.

Assessment of nutritional status in the Amazigh children of Amizmiz (Azgour Valley, High Atlas and Morocco).

The Berbers of the High Atlas (Amazigh) live in very severe socio-economic and climatic conditions, which expose children to the risk of malnutrition. In this study we used anthropometry and bioelectrical impedance analysis for the assessment of nutritional status. Height, weight and bioelectrical parameters were taken on 71 children (28 boys and 43 girls). Height and BMI were standardized using the 2007 WHO reference. The results show that 36.6% of the children were classified as stunted and 8.5% as wasted. Based on the Bioelectrical Impedance Vector Analysis, children from the High Atlas had an adequate body cell mass, but a high risk of dehydration (42.3%).

Helicobacter pylori and intestinal parasites are not detrimental to the nutritional status of Amerindians.

Gastrointestinal parasites have evolved with humans and colonize many asymptomatic subjects. We investigated the influence of microbial gastrointestinal colonization on the nutritional status of rural Amerindians (40 males and 61 females). Helicobacter pylori was detected by 13C-breath test, and intestinal parasites were detected in fecal specimens. Body morphometry and bioelectrical impedance measurements were measured. Although Amerindians showed low height and weight for age, they had an adequate body mass index, morphometric parameters, and cell mass. Intestinal parasites were detected in 99% of the subjects, with no detrimental effect on nutritional parameters. Helicobacter pylori was present in 82% of adults and half the children, and was positively correlated with improved nutritional status. Despite the high prevalence of gastrointestinal microbes often associated with disease, the studied population of Amerindians had a body morphometry and composition indicative of good nutritional status, and improved in children positive for gastric H. pylori.

Dispersion dimorphism in human populations.

The aim of this paper is to verify the existence of dispersion (or variability) dimorphism in several anthropometric traits, i.e., some skeletal, muscular, and adipose dimensions, and to provide an evaluation of this scarcely considered aspect of sex differences. This research focuses on two human samples from two different European regions, Sardinia (Italy) and the Basque Country (Spain). Twenty-three anthropometric measurements were taken. A first qualitative analysis was carried out comparing the profiles of the coefficients of variation of each variable in both sexes. Secondly, the equality of variability was verified with different tests. In the normal case, Student's t-test, as proposed by Sokal and Braumann ([1980] Syst. Zool. 29:50-63), was applied. In the more general case, it was necessary to resort to resampling techniques. A suitable bootstrap test was constructed and the results were compared, when possible, with those obtained by other methods. The measurements showed parallel trends in the two populations. In particular, subcutaneous skinfolds showed significant dispersion dimorphism, with the greatest coefficients of variation in men. We suggest that this result was linked to stronger canalization in female dimensions related to the reproductive function and influenced by sociocultural factors. We also suggest defining dispersion dimorphism, whose existence is confirmed by the results presented in this paper, as a descriptive pattern of phenotype variability in both sexes that can be specific of a given class of anthropometric traits.