Browsing by Subject "adherence"
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Item Development of an in vitro Model of Probiotic Adherence and Colonization for Poultry(2013-01-15) Spivey, MeganProbiotics are live microorganisms which when consumed in adequate amounts confer a health benefit upon the host. Commonly associated with the gastrointestinal tract of warm blooded animals, Lactobacillus species are often used as probiotics. Benefits of probiotic Lactobacillus use include improved digestive health, immune modulation, and increased resistance to enteric pathogens. Benefits of probiotic administration to poultry production include improved performance and feed conversion, reduced mortality, and improved food safety due to reduced colonization by human foodborne pathogens. Adherence to intestinal epithelia and persistence in the gastrointestinal tract is antecedent to the realization of benefits of probiotic lactobacilli. Lactobacillus species produce proteins, including fibronectin binding proteins, mucus binding proteins, and surface layer proteins, that associate with host factors and are responsible for bacterial adhesion. In vitro assays based on stable cell lines have been used to investigate adherence of Lactobacillus to epithelial cells. However, there have been no studies using poultry derived epithelial cell lines. In this study, we have developed an assay based on the chicken LMH epithelial cell line to investigate adherence and colonization of Lactobacillus species in poultry. Adherence assays revealed Lactobacillus crispatus ST1, Lactobacillus crispatus JCM 5810, Lactobacillus gallinarum ATCC 33199, and Lactobacillus gallinarum JCM 8782 were able to effectively adhere to the chicken LMH cell line when compared to low-adherent Bacillus subtilis and high-adherent Salmonella controls. Administration of these rifampicin resistant variants of these Lactobacillus cultures to broiler chicks revealed these cultures to transiently colonize the gastrointestinal tract. L. crispatus ST1 and L. gallinarum ATCC 33199 were found to persist more effectively than L. crispatus JCM 5810 and L. gallinarum JCM 8782. These studies of the adherence and colonization of poultry by Lactobacillus cultures are expected to contribute to improved understanding of the functionality of these microorganisms in poultry production.Item The effects of low-shear modeled microgravity on Streptococcus pneumoniae and adherent-invasive Escherichia coli(2007-07-20) Christopher Ashley Allen; Dr. Alfredo Torres; Dr. Ray Stowe III; Dr. Duane Pierson; Dr. David Niesel; Dr. Ashok ChopraThe effects of low-shear modeled microgravity (LSMMG) were investigated on Streptococcus pneumoniae global gene expression and on adherent-invasive Escherichia coli (AIEC) physiology and colonization properties. Habitation in space exposes both humans and microbes to microgravity conditions which are characterized by reductions in fluid shear forces. Areas of low-shear stress are also encountered in physiologically relevant regions of the body including the respiratory, gastrointestinal, and urogenital tracts. The LSMMG environment impacts both bacterial physiology and virulence properties and can be modeled using rotating-wall bioreactors known as high-aspect ratio vessels (HARVs). \r\nPrevious studies have evaluated the global transcriptional profiles of Gram-negative bacteria; however, no Gram-positive species have been examined. Microarray analysis of S. pneumoniae strain TIGR4 (serotype 4), after growth under LSMMG, revealed a dramatic down-shift in gene expression based on cluster analysis. Within this group of responsive genes, statistical analyses revealed that the expression of 81 genes was significantly altered. These genes were found to be associated with 7 different functional categories, including many which were uncharacterized. Several gene groups shared common functional operons and regulons such as those involved in competence induction, antimicrobial peptide production, and carbohydrate uptake. \r\nWhile previous studies examining the effects of LSMMG on bacteria have focused on well-characterized strains of both commensal and pathogenic species, there is limited information regarding the effects of LSMMG on clinical isolates associated with Crohn’s Disease, an inflammatory bowel pathology. Analysis of wild-type AIEC strain O83:H1 and an isogenic rpoS mutant (CAA001), after growth under LSMMG, revealed alterations in environmental stress resistance and increased adherence. Altered resistances to thermal and osmotic stresses were observed by LSMMG-grown AIEC O83:H1, while resistance to oxidative and acid stresses appeared to be rpoS-dependent. Further, CAA001 displayed a hyper-adherent phenotype while grown under LSMMG. TnphoA mutagenesis was used to abolish the hyper-adherent phenotype of CAA001 under LSMMG, and the insertion was mapped within the tnaB gene, encoding tryptophan permease. Complementation of the tnaB gene in the rpoS tnaB double-mutant restored adherence capabilities. These findings extend our understanding of how mechanical forces (e.g. LSMMG) can affect the functions of Gram-positive and Gram-negative species.\r\nItem Relationships between psychosocial factors and adherence to diet and exercise in adults with type 2 diabetes: A test of a theoretical model(2007-05-21) Elizabeth Gressle Tovar; Michele Clark, RN, PhD; Susan Weller, PhD; Regina Lederman, RN, PhD; Hoang Nguyen, PhD; Carrie Jo Braden, RN, PhDIntroduction: Cardiovascular disease (CVD) is the leading cause of premature death among people with diabetes. Diet and exercise adherence are\r\nimportant diabetes self management behaviors that can reduce CVD risk; unfortunately, adherence rates are low among diabetics. Improved understanding of psychosocial factors related to diet and exercise adherence among adults with\r\ntype 2 diabetes can improve strategies to reduce CVD morbidity and mortality in this population.\r\n Purpose: 1) Evaluate psychometrics of the Health Beliefs related to Cardiovascular Disease scale (HBCVD) which measures perceived susceptibility to and severity of heart attack or stroke and perceived benefits of and barriers to\r\ndiet and exercise; 2) Explore relationships between selected bio-psychosocial factors and diet and exercise adherence; and 3) Evaluate the ability of a theoretical model integrating the Health Belief Model (HBM) and Stages of Change Model (SOC) to explain diet and exercise adherence.\r\n Methods: The study design was a descriptive correlational cross section using a convenience sample of 212 adults with type 2 diabetes who completed a series of questionnaires measuring study variables. Outcome variables measured were diet and exercise adherence scores. Predictor/independent variables included knowledge related to CVD risk, cues to action, health beliefs, stage of change, social support, depression, comorbidity, diabetes duration, and\r\nsocioeconomic status. Relationships among model variables were explored using analysis of variance and simple and multiple regression techniques.\r\n Results: The HBCVD demonstrated evidence of validity and reliability, although an improved barriers subscale is recommended. The theoretical model was not supported, although significant paths between model variables were identified. The best model to predict diet included diet stage, susceptibility, self efficacy, social support, and age. The best model to predict exercise included\r\nexercise stage, self efficacy, and social support. Models including HBM and SOC provided greater explanatory power for diet and exercise adherence than either model alone. Susceptibility, barriers, and self efficacy varied significantly across\r\nstages of change. Significant group differences were found among model variables. Participants with depressive symptoms and the least education had lower diet and exercise adherence scores. Younger age and unemployment were also associated with lower diet adherence.\r\n