Browsing by Subject "calcium"
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Item Dietary calcium intake and overweight in adolescence(Texas A&M University, 2005-02-17) Gerges, Amira SamiRecent research has shown an association between low dietary calcium intake and obesity in adults as well as overweight in young children; however, this relationship has not been investigated in adolescents. The purpose of this study was to examine the relationship between inadequate calcium intake and overweight in adolescents. The hypothesis of this study was that there is a negative correlation between dietary calcium intake and overweight in adolescents. The study population consisted of middle school and high school students (n = 102) in a local school district. The gender and ethnic distributions of the sample were as follows: 74% female, 26% male, 63% Caucasian, 16% African-American, 12% Hispanic, and 8% other. Dietary calcium and energy intakes were assessed using a previously validated calcium-focused food frequency questionnaire (FFQ) for youths. Calcium intake was also assessed using a single question on daily milk consumption. The FFQ was administered by trained interviewers to groups of three to five students. Body fat was assessed using body mass index for age (BMI-for-age) and sum of triceps and subscapular skinfolds (STS). The mean reported calcium intake was 1,972 ? 912 mg/day, and mean reported energy intake was 3,421 ? 1,710 kcals/day. Reported calcium intake from the FFQ was inflated since approximately 75% reported drinking less than three glasses of milk a day. According to BMI-for-age, 29% were classified as at risk of overweight or overweight. Using STS, 39% were classified as overweight. Chi-square analysis using either method of dietary calcium intake and either method of overweight assessment did not show dependence between categories of calcium intake and level of weight or body fat. This study failed to show a relationship between dietary calcium intake and risk of overweight or overweight in adolescents.Item Evaluation of oocyte competency in bovine and canine species via non-invasive assessment of oocyte quality(2009-05-15) Willingham-Rocky, Lauri A.Traditional methods of oocyte selection for in vitro studies have proven inefficient with respect to achieving a level of predictability for competency. In this study, a novel method of oocyte selection was implemented that identified a relationship between oocyte morphological parameters (as defined by a ratio of a shape factor (SF) to average fluorescence intensity (AFI) and AFI, followed by in vitro fertilization (IVF) and in vitro culture (IVC) using the Well of Well (WOW) method to evaluate oocyte competency. Specifically, we used non-cytotoxic fluorescent molecular probes and multiphoton microscopy to non-invasively characterize spatial localization and functional activity of mitochondria, mitochondrial membrane potential (??m), and intracellular calcium activity ([Ca2+]i) using rhodamine 123, JC-1 and Fluo-4, AM, respectively in bovine and canine in vitro matured (IVM) oocytes. Comparison of morphological grading with fluorescence intensity yielded similar trends between all grades of oocytes for both species with no visually obvious, distinct characteristic staining that would permit classification of each oocyte as a specific morphological grade. Our studies confirmed that oocyte mitochondria were homogeneously distributed but primarily localized to the peri- and sub-cortical regions of the oocyte at MII stage for both species. Further, heterogeneously polarized mitochondria were localized to the peri- and sub- cortical regions of the oocyte for both species. In bovine oocytes labeled with Fluo-4, AM, levels of [Ca2+]i were either unremarkable, or very low and limited to the peri-cortical areas, just beneath the oolema. For canine MII stage oocytes, levels of [Ca2+]i were within the same range of AFI as bovine. Ranges of fluorescence intensity compatible for optimal embryo development for bovine and optimal fertilization for canine oocytes were 30-300 and 20-35, and 20-30 and 20-25.5 for rhodamine 123 and Fluo-4, AM, respectively. The optimal range for bovine oocytes imaged with JC-1 was 1.25-2.25 and <6 for canine.Item Hyperactivated Motility of Stallion Spermatozoa(2013-12-02) Loux, Shavahn CIn vitro fertilization does not occur readily in the horse. Recent evidence suggests that this is due to failure to initiate hyperactivated motility in vitro; however, little is known about the induction of hyperactivated motility in equine sperm. In mice, hyperactivated motility requires the CatSper channel, a pH-gated calcium channel, therefore we investigated this channel and its related intracellular changes, alkalinization and calcium influx, in equine sperm. Motility was assessed by computer-assisted sperm motility analysis, andchanges in intracellular pH and calcium were determined via the calcium and pH-specific fluorescent probes, BCECF-AM, Fluo3-AMand Fluo4-AM. Additionally, a demembranated sperm model was developed to investigate the direct effect of major regulators of sperm motility on axonemal function. Increasing intracellular pH induced a rise in intracellular calcium, which was inhibited by the known CatSper blocker mibefradil, supporting the presence of a pH-gated calcium channel, presumably CatSper, in equine sperm. Hyperactivation was induced by treatment with high-pH medium, procaine and 4-aminopyridine. Hyperactivation was associated with moderately increased intracellular pH, but appeared inversely related to increases in intracellular calcium. Sperm treated with procaine in calcium-deficient media both maintained motility and underwent hyperactivation, suggesting that extracellular calcium was not required for hyperactivation. CATSPER1 protein was localized to the principal piece of equine sperm on immunocytochemistry. Analysis of the predicted equine CATSPER1 protein revealed species-specific differences in structure in the pH-sensor region. Demembranated equine sperm required ATP for reactivated motility, but did not require cAMP. Motility of demembranated equine sperm was not inhibited by elimination of calcium (chelation to below 20 pM). Excess calcium inhibited motility at concentrations lower than those reported in other species. Calcium-inhibited sperm arrested with a straight tail rather than in a curve, as seen with calcium arrest in other species. Hyperactivated-like motility was not induced at any pH or calcium concentration. Equine sperm were not inhibited by cadmium at concentrations that profoundly inhibit motility in demembranated sperm in other species. These findings indicate species-specific differences in calcium regulation of sperm motility which may relate directly to the inefficiency of functional capacitation of equine sperm under standard in vitro conditions.Item Microvascular endothelial response to cocaethylene exposure: morphological and molecular observations(2004-11-02) Danyel Hermes Tacker; Anthony O. Okorodudu, Ph.D.; Robert H. Glew, Ph.D.; Norbert K. Herzog, Ph.D.; M. Tarek Elghetany, M.D.; Kathryn A. Cunningham, Ph.D.; Hal K. Hawkins, M.D., Ph.D.Cocaethylene (CE) is an active metabolite of cocaine and ethanol and is a toxicant of physiological relevance due to the high rate of cocaine and ethanol co-exposure (~80%) in cocaine abusers. It has prolonged action and increased potency on known physiological targets relative to the effect of cocaine. Since pathology in cocaine abusers is typically chronic and systemic, and CE persists in the body three to five times longer than cocaine, a link between CE and systemic disease in cocaine abusers was proposed. Consequently, this dissertation contains the studies that were used to test the hypothesis that the microvascular endothelium is a target tissue that is central in the pathogenic mechanism of cocaine-associated systemic disease, and that endothelial injury after CE exposure would result in dysregulation and altered barrier function due to changes in intracellular second messengers and signaling. To test this hypothesis, an in vitro model of CE exposure in human dermal microvascular endothelial cells (HMEC-1) was developed. Four Aims were designed to compartmentalize various components of the endothelial response to CE. The Aims included an array of methods to address cellular toxicity and dysfunction, including classical cytotoxicity and viability assays (Aim One), microscopic and electrical analyses of monolayer integrity (Aim Two), molecular analysis of second messengers, signaling molecule phosphorylation, and transcription factor DNA binding activity (Aims Three and Four). Aim One experiments demonstrated a lack of overt endothelial cytotoxicity caused by CE. Aim Two morphological analysis of endothelial intercellular borders and barrier integrity showed that CE exposure in the endothelial monolayers resulted in increased permeability, and hence a decrease in barrier integrity. These changes were observed temporally with alterations in cytosolic and total cellular free calcium ion (Aim Three), inositol 1,4,5 trisphosphate, and phosphorylated p38 mitogen-activated protein kinase concentrations, as well as changes in DNA binding activity and dimer composition of nuclear factor-kappaB (Aim Four). The observed changes suggest a distinct alteration of endothelial cell and monolayer function consistent with increased vascular permeability in vivo. Potential pathological outcomes of such effects include inflammation, vasculitis, systemic disease, and organ failure.Item Molecular and Genetic Analysis of Adaptive Evolution in the Rare Serpentine Endemic, Caulanthus amplexicaulis var. barbarae (J. Howell) Munz(2011-10-21) Burrell, Anna MildredIn the interest of understanding the genetic basis of adaption to environment, we developed F2 lines from an F1 interspecific cross between the rare serpentine endemic, Caulanthus amplexicaulis var. barbarae and the non-serpentine Caulanthus amplexicaulis var. amplexicaulis. Using genomic DNA from Caulanthus amplexicaulis var. barbarae, we developed a suite of microsatellite markers. In addition, we developed gene specific markers for genes known in Arabidopsis to be ecologically important. Our suite of markers was used to genotype 186 F2 plants, the basis for our F2 linkage map. In order to further resolve evolutionary relationships among related taxa, we constructed a molecular phylogeny for 52 taxa within the related genera Caulanthus, Guillenia, Sibaropsis, Streptanthella, and Streptanthus, using the sequences from the ribosomal ITS region and two chloroplast regions. To create a useful system to enable comparative genomics within the related taxa of the ecologically and morphologically diverse Streptanthoid Complex, we demonstrated that our molecular tools are portable across a large group of ecologically significant taxa. To use the significant genomic resources available in Arabidopsis, we constructed a collinear comparative map of Caulanthus and the model plant Arabidopsis thaliana based on ancestral linkage blocks with the Brassicaceae family. This comparative map acted as a guide for candidate gene selection in the mapping of sepal color. We identified a region of MYB transcription factors in an orthologous region of Arabidopsis. Sequence data from Caulanthus amplexicaulis var. barbarae and Caulanthus amplexicaulis var. amplexicaulis in this MYB region showed significant sequence divergence between the two taxa. To determine the genetic basis for the tolerance of high concentrations of magnesium in Caulanthus amplexicaulis var. barbarae, we phenotyped multiple individuals from 88 F2:3 families under two nutrient treatments, differing in the ratio of calcium to magnesium. Through QTL analysis, using our F2 linkage map as a framework for the analysis, we identified one major effect QTL on Caulanthus Linkage Group 8 and another QTL on Caulanthus Linkage Group 3. We identified candidate genes for the QTLs using our collinear comparative map to Arabidopsis.Item n-3 Polyunsaturated Fatty Acids Suppress Mitochondrial Translocation to the Immunological Synapse and Modulate Calcium Signaling in T Cells(2011-02-22) Yog, RajeshwariT helper (Th) cell activation is necessary for the adaptive immune response. Formation of an immunological synapse (IS) between Th cells and antigen-presenting cells is the first step in Th cell activation. In vitro studies indicate that formation of the IS induces cytoskeleton-dependent mitochondrial redistribution to the immediate vicinity of the IS. This redistribution of mitochondria to the IS in T cells is necessary to maintain Ca2 influx across the plasma membrane and Ca2 -dependent Th cell activation. Earlier studies have demonstrated that n-3 polyunsaturated fatty acids (PUFA) suppress the localization and activation of signaling proteins at the IS. Therefore, we hypothesized that n-3 PUFA suppress CD4 T cell mitochondrial translocation during the early stages of IS formation and down-modulate Ca2 dependent Th cell activation. CD4 cells derived from fat-1 mice, a transgenic model that synthesizes n-3 PUFA from n-6 PUFA, were co-cultured with anti-CD3-expressing hybridoma cells (145-2C11) for 15 min at 37 degrees C, and mitochondrial translocation to the IS was assessed by confocal microscopy. fat-1 mice exhibited a significantly (P< 0.05) reduced percentage of CD4 T cells with mitochondria which translocated to the IS; fat-1 (30 percent) versus wild type control (82 percent). With respect to an effect on the mitochondrial-to-cytosolic Ca2 ratio, wild type cells showed significant increases at the IS (71 percent) and total cell (60 percent) within 30 min of IS formation. In contrast, fat-1 CD4 T cells remained at basal levels following the IS formation. A similar blunting of the mitochondrial-to-cytosolic Ca2 ratio was observed in wild type cells co-incubated with inhibitors of the mitochondrial uniporter, RU360 or calcium release-activated Ca2 (CRAC) channels, BTP2. Together, these observations provide evidence that n-3 PUFA modulate Th cell activation by limiting mitochondrial translocation to the IS and reducing Ca2 entry.Item Relationships between Beef Postharvest Biochemical Factors and Warner-Bratzler Shear Force(2013-04-01) Orozco Hernandez, PilarBiochemical changes in muscle postmortem have been associated with initial beef tenderness early postmortem, and with improvements in tenderness during postmortem storage, defined as meat aging. Differences in the initial contractile state of the sarcomere, the ionic environment of the sarcoplasm including pH, the activity of neutral proteolytic enzymes, and collagen content and solubility have been associated with beef tenderness. In Phase I, steaks from four genetic lines of steers and heifers were used to understand the biochemical differences between tough and tender steaks. The most tender (< 30 N Warner Bratzler shear force (WBS)) and toughest Longissimus steaks (< 30 N WBS) from Angus, Braford, Brangus, and Simbrah heifers and steers were used. For Phase II, samples were obtained from a subset of Santa Cruz yearling heifers selected based of genotypes for tenderness (tough and tender) using a commercial genetic marker. Within genotype for tenderness, each animal was randomly assigned to one of four growth enhancement treatments. The most tender (< 30 N WBS) and toughest Longissimus steaks (< 30 N WBS) were selected for use in this study. In Phase I, tough steaks after 3, 10, and 17d postmortem had higher (P < 0.0005) WBS values than tender steaks. Tender steaks came from carcass with slightly higher (P = 0.008) marbling score and (P = 0.01) Quality grade. Sarcomere length, total and soluble collagen, potassium concentration, and m and ?calpain did not differ (P > 0.05) between tough and tender steaks. Sodium concentration at 10 d was higher (P = 0.03) in tough steaks, but only account for 0.05% of the variation in WBS at 3d. Tender steaks had less (P = 0.04) intact desmin at 24h, but intact desmin was not correlated (P > 0.05) with WBS. In Phase II, tough steaks after 3, 10, and 17d postmortem had higher (P < 0.0001) WBS values than tender steaks. Tender steaks came from carcass with slightly higher (P < 0.03) marbling score and (P = 0.02) Quality grade. Tender teaks were slightly lighter (P = 0.02), with more red (P = 0.02) and yellow (P = 0.007) color, and had slightly lower (P = 0.02) pH, compared with tough steaks. Sarcomere length, total and soluble collagen, sodium and potassium concentration, and m and ?calpain did not differ (P > 0.05) between tough and tender steaks. Tender steaks had less (P < 0.0001) intact desmin at 17d postmortem than tough steaks. Intact desmin at 17d was responsible for 4%, 47%, and 30% of WBS variation after 3, 10, and 17d postmortem, respectively. The slight difference in marbling and quality grade did not account for a significant amount of variation in WBS. However, meat color and pH accounted for variation in shear WBS. Calcium flux may have influenced meat tenderness by activation of calpains and may have altered protein to protein interactions. Results suggested that marbling, ? calpain activity, and desmin degradation, and to a lesser extent pH and meat color contributed to meat tenderness.Item Seasonal isotope and trace-metal profiles of serially-sampled Conus gastropods: proxies for paleoenvironmental change(Texas A&M University, 2006-08-16) Gentry, David KeithWe test the fidelity of shallow-water gastropod skeletons as multi-proxy archives of seasonal paleo-environmental change by performing isotopic and trace-metal analyses on specimens of Conus ermineus from the Gulf of Mexico. Four adult specimens were collected from Stetson Bank in the Flower Garden Banks National Marine Sanctuary during the summer of 2002. Shell samples were milled along axes of growth to produce time-series profiles spanning up to eight years. We corrected the profiles for growth rate effects and compared the tuned results with in situ temperature and salinity records at the reef surface and temperature profiles from nearby surface buoys. Examination of sample densities in δ18O cycles shows that shell growth is faster during summers and slower during winters. Tuning the profiles versus time yields δ18O values that co-vary closely with seasonal temperatures to a high degree of coherency (R2 = 0.84). The δ13C profiles show cyclic variation modified by ontogenetic decreases in δ13C. These ontogenetic trends are attributable to decreasing metabolic efficiency, while seasonal cycles reflect hydrographic changes in the gastropods?? habitat. Salinity and δ13C of dissolved inorganic carbon show a strong correlation at Stetson Bank (R2 = 0.80), and early summer shell δ13C minima coincide with local salinity minima during times of peak river discharge. The terminations of these δ13C minima occur during annual upcoast reversals of shelf currents in this area. These effects are augmented by summer stratification and productivity minima that further decrease seawater δ13C. Sr/Ca ratios increase through ontogeny, most likely due to decreasing metabolic efficiency. However, seasonal variations in Sr/Ca profiles show strong similarity with δ18O profiles, confirming the temperature dependence of Sr/Ca and minimal influence of salinity on shell δ18O at Stetson Bank. The results of this study show that tuned δ18O and Sr/Ca profiles can be used to reconstruct seasonal paleotemperatures. Carbon isotope profiles and environmental data also demonstrate the utility of Conus δ13C as a proxy for freshwater flux and shelf circulation.