Bootstrap parametric GB2 and bootstrap nonparametric distributions for studying shiga toxin-producing Escherichia coli strains growth rate variability.

Shiga toxin-producing Escherichia coli (VTEC) strains, including the serotype O157:H7, are considered foodborne pathogens. Transmission occurs through consumption of undercooked meat, unpasteurized dairy products, vegetables, or contaminated water. The variability of pathogenic and nonpathogenic E. coli strains growth parameters at different temperatures and in different media was studied. Bootstrap parametric (Generalized Beta of the Second Kind, GB2) or nonparametric models were used. GB2 estimations show increased growth rates and shortened lag times with increased temperature, as expected. Similar estimations were obtained using the nonparametric model. Parametric and nonparametric growth rate confidence intervals were wider with increased temperature; lag times confidence intervals were wider with decreased temperature. The nonparametric method gives similar confidence intervals to the parametric method, confirming its suitability for growth parameters estimation. The estimations obtained from nonpathogenic E. coli strains approximate distributions from pathogenic E. coli strains.

Different displacement of bioimpedance vector due to Ag/AgCl electrode effect.

BACKGROUND/OBJECTIVES: Bioelectrical impedance vector analysis (BIVA) is increasingly used in clinical research to assess soft tissue hydration. It is known that physical characteristics of electrodes, such as low intrinsic impedance, low electrode/skin contact impedance and type of gel, affect the reliability of noninvasive bioimpedance assessments. The aim of this study was to determine the effect of intrinsic impedance of electrode on the bioimpedance vector displacement in RXc graph. SUBJECTS/METHODS: The intrinsic impedance is measured in nine pregelled disposable Ag/AgCl electrodes usually used for bioimpedance measures. The BIVA method is performed on 35 healthy volunteers using a 50 kHz phase-sensitive bioimpedance analyzer (BIA 101 Anniversary) with the lowest intrinsic impedance electrode and highest. The individual bioimpedance vector is plotted on the bivariate normal interval of reference population. The differences in the mean bioimpedance vectors obtained with each electrode are plotted, with their 95% confidence ellipses, on the dRXc graph. The paired one-sample Hotelling's T2-test is used to compare the differences of the mean bioimpedance vectors. RESULTS: We found large variability in intrinsic resistance (11-665 Ω) and reactance (0.25-2.5 Ω) values of the electrodes analyzed and significant displacement (P<0.05) of bioimpedance vector positions in healthy adults according to the paired one-sample Hotelling's T2-test. CONCLUSIONS: A robust study of all physical characteristics of commercial Ag/AgCl electrodes is necessary to reach consensus on pregelled Ag/AgCl electrodes valid for bioimpedance measurement. This information will enable BIVA users to avoid systemic errors when performing BIVA assessments, specifically when these measurements are used for clinical interpretations.

Body composition analysis in older adults with dementia. Anthropometry and bioelectrical impedance analysis: a critical review.

In clinical practice, geriatric nutritional assessment usually includes nutritional screening, a simple anthropometric assessment, measurement of various biochemical parameters, such as serum albumin, and sometimes (not always) body composition analysis (BCA). However, there is a high prevalence of undiagnosed malnutrition in patients with dementia. Several factors contribute to this situation; probably, the most notable is the methodology used to assess body composition (BC). In this regard, for BCA, techniques are needed that are noninvasive, affordable, safe, simple and that require the minimum possible collaboration by the elderly patient. Consequently, body mass index (BMI) and waist circumference (WC) are widely used as indicators of overall and central adiposity, respectively; however, there is no consensus on the cutoffs for the elderly, and changes in BC (especially muscle-mass depletion) are masked by normal values of BMI and WC. Bioimpedance analysis is a simple, cost-effective and precise method for BCA, provided that cross-validated equations are used. Its main disadvantage is that it is highly sensitive to changes in body water (overhydration or dehydration), leading to substantial errors in BC estimates. However, using Bioelectrical Impedance Vector Analysis errors are minimized, as there is no need for the subject to be normally hydrated and it does not require the use of predictive models.

[Presence of malnutrition and risk of malnutrition in institutionalized elderly with dementia according to the type and deterioration stage]. / Presencia de malnutrición y riesgo de malnutrición en ancianos institucionalizados con demencia en función del tipo y estadío evolutivo.

OBJECTIVE: To determine if there exist differences in the nutritional status of patients with dementia according to the type and severity of the disease. METHOD: In this cross-sectional study we carried out an assessment of the nutritional status (anthropometrical assessment, Mini Nutritional Assessment, Chang's protocol) in 83 institutionalized elderly diagnosed with dementia at evolutionary states of 5, 6, and 7 of GDS (Global Deterioration Scale) and FAST (Functional Assessment Stating). The results were analyzed by the Chi-squared, ANOVA, or Kruskal-Wallis tests, the Scheffé's posteriori contrasts, and the linear trend test. Significance was considered at p < 0.05. RESULTS: The mean age of the patients was 81.22 years. The BMI revealed that 21% of the sample were at risk for malnourishment and 14.5% were malnourished. However, by using the MNA, 56.6% of the patients were at risk for malnourishment and 41% were malnourished. According to the Chang's method, the percentage of malnourished patients was increased to 75.9%. None of these variables showed an association with the type of dementia. A significant association was observed between the evolutionary state of dementia and the BMI (p = 0.004), MNA (p = 0.002 and p = 0.006 for the score and the category, respectively), the muscle circumference of the arm (p = 0.043) and the calf circumference (p = 0.043) but not with the percentage of fat mass nor the nutritional diagnosis established by the Chang's method (degree and type of MN). The linear trend test confirmed that both the MNA and BMI scores and the muscle circumference of the arm and the calf circumference were lower in the more severe dementia states. CONCLUSION: Irrespective of the type of dementia, the presence of malnourishment in institutionalized elderly increases in parallel to the evolutionary degree of the dementia.

Guidelines for nutrition support in the elderly.

Nutritional support in the elderly not only co-operates in pharmacological treatment but also very often is a primary therapy for their health. The type of artificial nutrition (AN) to use will depend on the present illness and the previous health record. Due to the fact that enteral feeding (EF) is less expensive and aggressive we should use EF whenever possible, leaving parenteral nutrition (PN) for specific situations where EF should not be used. AN, if properly prescribed, formulated, administered and monitored, is safe as long as qualified personnel are trained in its use. Combined AN (oral, enteral and parenteral) allows a step-by-step improvement that could lead to final oral feeding. Finally, while it is true that age should not be considered in isolation as a contraindication for AN, we should be aware that, in final life stages, oral feeding can be the only satisfaction left for the elderly.

[The zinc status in a selected Spanish population. A multivariate analysis]. / Status de zinc en una población española seleccionada. Análisis multivariante.

There are no previous studies on the zinc status in the healthy, adult, Spanish population. The objective of this study was to obtain the levels of zinc in the serum and hair of this population to determine the normal nutritional status of zinc, and evaluating the influence of certain factors like age, sex, type of residence, body mass index (BMI) hair color, or recent food intake (zinc and fiber contents of the diet) on this status. Using a simple randomized sampling, 186 blood donors of both sexes with ages comprised between 18 and 65 years, were selected. The results were analyzed using uni- and multi-variate statistical techniques. The average concentration of zinc in serum was 97.22 micrograms/dl (95% CI: 95.1-99.4); the average zinc level in hair was 163.86 micrograms/g (95% CI: 157.8-169.9). The serum zinc was individually associated with the type of residence and the zinc and fiber contents of the diet. The zinc in hair was associated with sex, age, body mass index, and hair color. Using a multivariate analysis, predictive models of multiple regression were obtained for the serum zinc: y = 109.69 - 1.39 (dietary zinc) - 4.63 (sex) - 0.65 (dietary fiber), for the zinc in the serum, and y = 199.34 + 26.62 (sex) - 2.08 (BMI) - 0.47 (age) for the zinc in the hair. The serum concentration decreases as the dietary zinc and fiber decreases and women have lower levels. The zinc in hair is increased in women and is reduced with increasing age and BMI.

[Nutrition and gene expression]. / Nutrición y expresión génica.

The genetic information stored in the DNA is transmitted to an RNA molecule through transcription and protein molecules are obtained from the RNA using translation techniques. Each of the processes forming part of this chain is the object of complex regulation (gene expression regulation). Some nutrients may affect gene expression by taking part in these regulatory mechanisms, such as sterols, glucose, vitamins A, D and B12, various fatty acids or some components of dietary fibre. These phenomena may have come about through the adaptation of the primitive beings to the various changes in the nourishment available. The successive changes over centuries have led to the determination of individuals' phenotypes not only by their genotype but also by environmental factors such as diet. Our genes have adapted to the changing sources of nourishment surrounding our ancestors; modern diets are, however, very different from those of the past. The inability of our genetic store to adapt to modern diets may be the reason for the appearance of certain chronic diseases in developed countries. One well-analyzed case is that of the thrifty genotype which provided evolutionary advantages in the past, but may now be contributing to obesity and diabetes. Further examples of genotype interaction with various environmental factors to produce different phenotypes are provided by the apolipoproteins: some mutations in the genes of these proteins, in combination with different diet types, are associated with altered lipid levels and the risk of various cardiovascular diseases. These diet-genotype interactions mean that it is fundamentally important to take into account the genetic variability of individuals before recommending dietary measures to prevent the so-called "first-world" diseases.