Interplay Between Gut Microbiota and Gastrointestinal Peptides: Potential Outcomes on the Regulation of Glucose Control.

A host of gastrointestinal (GI) peptides influence the regulation of vital functions, such as growth, appetite, stress, gut motility, energy expenditure, digestion and inflammation, as well as glucose and lipid homeostasis. Hence, impairments in the synthesis/secretion of glucagon-like peptide-1 (GLP-1), leptin, nesfatin-1, glucose-dependent insulinotropic peptide (GIP), ghrelin (acylated and unacylated forms), oxyntomodulin, vasoactive intestinal peptide, somatostatin, cholecystokinin, peptide tyrosine‒tyrosine, GLP-2 and pancreatic polypeptide were previously associated with the development of obesity-related disorders. It is currently emphasized that the beneficial metabolic outcomes associated with the normalization of the gut microbiota (GM) is influenced by increases in GLP-1 and peptide YY secretion as well as by decreases in acylated ghrelin production.

A-priori Weighting of Items with the Rasch Model.

Many assessment scales in the social sciences are composed of multiple items that form a subscale structure. They have this structure because more than one aspect of the variable is assessed and more than one item assesses each aspect. Nevertheless, generally, a single measurement is required from the scale.

A Short-Term High-Fat Diet Alters Glutathione Levels and IL-6 Gene Expression in Oxidative Skeletal Muscles of Young Rats.

Obesity and ensuing disorders are increasingly prevalent worldwide. High-fat diets (HFD) and diet-induced obesity have been shown to induce oxidative stress and inflammation while altering metabolic homeostasis in many organs, including the skeletal muscle. We previously observed that 14 days of HFD impairs contractile functions of the soleus (SOL) oxidative skeletal muscle.

A Law of Comparative Preference: Distinctions Between Models of Personal Preference and Impersonal Judgment in Pair Comparison Designs.

The pair comparison design for distinguishing between stimuli located on the same natural or hypothesized linear continuum is used both when the response is a personal preference and when it is an impersonal judgment. Appropriate models which complement the different responses have been proposed. However, the models most appropriate for impersonal judgments have also been described as modeling choice, which may imply personal preference.

Altered Lipid Metabolism Impairs Skeletal Muscle Force in Young Rats Submitted to a Short-Term High-Fat Diet.

Obesity and ensuing disorders are increasingly prevalent in young populations. Prolonged exposure to high-fat diets (HFD) and excessive lipid accumulation were recently suggested to impair skeletal muscle functions in rodents. We aimed to determine the effects of a short-term HFD on skeletal muscle function in young rats.

Altered Feeding Behaviors and Adiposity Precede Observable Weight Gain in Young Rats Submitted to a Short-Term High-Fat Diet.

Information regarding the early effects of obesogenic diets on feeding patterns and behaviors is limited. To improve knowledge regarding the etiology of obesity, young male Wistar rats were submitted to high-fat (HFD) or regular chow diets (RCDs) for 14 days. Various metabolic parameters were continuously measured using metabolic chambers.

The impact of a short-term high-fat diet on mitochondrial respiration, reactive oxygen species production, and dynamics in oxidative and glycolytic skeletal muscles of young rats.

Multiple aspects of mitochondrial function and dynamics remain poorly studied in the skeletal muscle of pediatric models in response to a short-term high-fat diet (HFD). This study investigated the impact of a short-term HFD on mitochondrial function and dynamics in the oxidative soleus (SOL) and glycolytic extensor digitorum longus (EDL) muscles in young rats. Young male Wistar rats were submitted to either HFD or normal chow (NCD) diets for 14 days.

Recent advances in analysis of differential item functioning in health research using the Rasch model.

Background: Rasch analysis with a focus on Differential Item Functioning (DIF) is increasingly used for examination of psychometric properties of health outcome measures. To take account of DIF in order to retain precision of measurement, split of DIF-items into separate sample specific items has become a frequently used technique. The purpose of the paper is to present and summarise recent advances of analysis of DIF in a unified methodology.

Controlling response dependence in the measurement of change using the Rasch model.

The advantages of using person location estimates from the Rasch model over raw scores for the measurement of change using a common test include the linearization of scores and the automatic handling of statistical properties of repeated measurements. However, the application of the model requires that the responses to the items are statistically independent in the sense that the specific responses to the items on the first time of testing do not affect the responses at a second time. This requirement implies that the responses to the items at both times of assessment are governed only by the invariant location parameters of the items at the two times of testing and the location parameters of each person each time.

On the validity of repeated assessments in the UMAT, a high-stakes admissions test.

The possibility that the validity of assessment is compromised by repeated sittings of highly competitive and high profile selection tests has been documented and is of concern to stake-holders. An illustrative example is the Undergraduate Medicine and Health Sciences Admission Test (UMAT) used by some medical and dental courses in Australia and New Zealand. The proficiencies of all applicants who sat the UMAT from one to four sittings between 2006 and 2012 were estimated on the same metric using the probabilistic Rasch model.

Accounting for Local Dependence with the Rasch Model: The Paradox of Information Increase.

Test theories imply statistical, local independence. Where local independence is violated, models of modern test theory that account for it have been proposed. One violation of local independence occurs when the response to one item governs the response to a subsequent item.

Erratum: Accounting for local dependence with the Rasch model: The paradox of information increase.

Contains a correction to Table 5 in original publication appearing in Journal of Applied Measurement, 17, 262-282.

Acute effects of water immersion on heart rate variability in participants with heart disease.

Background: Water immersion and aquatic exercise can be an important therapeutic tool in patients suffering from heart disease (HD). However, the effects of water immersion on heart rate variability (HRV) in HD participants remain unknown.

Methods: Twenty-eight volunteers in sinus rhythm within the same age range took part in this study: 18 HD and ten healthy controls (HC).

Acute breathing patterns in healthy and heart disease participants during cycling at different levels of immersion.

We aimed to determine the effect of aquatic cycling and different levels of immersion on respiratory responses in healthy and heart disease (HD) volunteers. Thirty-four age matched volunteers, 21 HD and 13 healthy controls (HC) took part in this study. The ventilatory pattern, phase 1V and steady-state ventilatory responses to progressive exercise from 40 to peak rpm, were measured while participants exercised on a water stationary bike (WSB) at different levels of immersion.

Georg Rasch and Benjamin Wright's Struggle With the Unidimensional Polytomous Model With Sufficient Statistics.

This article reproduces correspondence between Georg Rasch of The University of Copenhagen and Benjamin Wright of The University of Chicago in the period from January 1966 to July 1967. This correspondence reveals their struggle to operationalize a unidimensional measurement model with sufficient statistics for responses in a set of ordered categories. The article then explains the original approach taken by Rasch, Wright, and Andersen, and then how, from a different tack originating in 1961 and culminating in 1978, three distinct stages of development led to the current relatively simple and elegant form of the model.

Controlling Guessing Bias in the Dichotomous Rasch Model Applied to a Large-Scale, Vertically Scaled Testing Program.

Recent research has shown how the statistical bias in Rasch model difficulty estimates induced by guessing in multiple-choice items can be eliminated. Using vertical scaling of a high-profile national reading test, it is shown that the dominant effect of removing such bias is a nonlinear change in the unit of scale across the continuum. The consequence is that the proficiencies of the more proficient students are increased relative to those of the less proficient.

Real and Artificial Differential Item Functioning in Polytomous Items.

Differential item functioning (DIF) for an item between two groups is present if, for the same person location on a variable, persons from different groups have different expected values for their responses. Applying only to dichotomously scored items in the popular Mantel-Haenszel (MH) method for detecting DIF in which persons are classified by their total scores on an instrument, Andrich and Hagquist articulated the concept of artificial DIF and showed that as an artifact of the MH method, real DIF in one item favoring one group inevitably induces artificial DIF favoring the other group in all other items. Using the dichotomous Rasch model in which the total score for a person is a sufficient statistic, and therefore justifies classifying persons by their total scores, Andrich and Hagquist showed that to distinguish between real and artificial DIF in an item identified by the MH method, a sequential procedure for resolving items is implied.

Practice effects in medical school entrance testing with the undergraduate medicine and health sciences admission test (UMAT).

Background: The UMAT is widely used for selection into undergraduate medical and dental courses in Australia and New Zealand (NZ). It tests aptitudes thought to be especially relevant to medical studies and consists of 3 sections - logical reasoning and problem solving (UMAT-1), understanding people (UMAT-2) and non-verbal reasoning (UMAT-3). A substantial proportion of all candidates re-sit the UMAT.

Achieving valid patient-reported outcomes measurement: a lesson from fatigue in multiple sclerosis.

Background: The increasing influence of patient-reported outcome (PRO) measurement instruments indicates their scrutiny has never been more crucial. Above all, PRO instruments should be valid: shown to assess what they purport to assess.

Objectives: To evaluate a widely used fatigue PRO instrument, highlight key issues in understanding PRO instrument validity, demonstrate limitations of those approaches and justify notable changes in the validation process.

Diagnosing a common rater halo effect using the polytomous Rasch model.

The 'halo effect' may be unique to different raters or common to all raters. When common to all raters, halo is not detectable through standard fit indices of the three-facet Rasch model used to account for differences in rater severities. Using a formulation of halo as a violation of local independence, a halo effect common to all raters is simulated and shown to be diagnosable through contrasts between two-facet stack and rack Rasch analyses.

Rating scales and Rasch measurement.

Assessments with ratings in ordered categories have become ubiquitous in health, biological and social sciences. Ratings are used when a measuring instrument of the kind found in the natural sciences is not available to assess some property in terms of degree - for example, greater or smaller, better or worse, or stronger or weaker. The handling of ratings has ranged from the very elementary to the highly sophisticated.

Relationship between essential amino acids and muscle mass, independent of habitual diets, in pre- and post-menopausal US women.

The purpose of this secondary analysis was to examine the relationship between protein and essential amino acids (EAAs) intake with the level of muscle mass (MM) independent of the diet. Twenty-one omnivores, 22 ovo-lacto-vegetarians and 20 vegans were recruited. MM (urinary creatinine), dietary intake (5-day dietary records) and biochemical analyses (urinary and plasma sex hormones) were obtained.

Distractors with information in multiple choice items: a rationale based on the Rasch model.

There is a substantial literature on attempts to obtain information on the proficiency of respondents from distractors in multiple choice items. Information in a distractor implies that a person who chooses that distractor has greater proficiency than if the person chose another distractor with no information. A further implication is that the distractor deserves partial credit.

Understanding the unit in the Rasch model.

The purpose of this paper is to explain the role of the unit implicit in the dichotomous Rasch model in determining the multiplicative factor of separation between measurements in a specified frame of reference. The explanation is provided at two complementary levels: first, in terms of the algebra of the model in which the role of an implicit, multiplicative constant is made explicit; and second, at a more fundamental level, in terms of the classical definition of measurement in the physical sciences. The Rasch model is characterized by statistical sufficiency, which arises from the requirement of invariant comparisons within a specified frame of reference.