University of Tennessee Health Science Center

About: University of Tennessee Health Science Center is a education organization based out in Memphis, Tennessee, United States. It is known for research contribution in the topics: Population & Medicine. The organization has 15716 authors who have published 26884 publications receiving 1176697 citations.

A new set of BXD recombinant inbred lines from advanced intercross populations in mice

Abstract: Recombinant inbred (RI) strains are an important resource for mapping complex traits in many species. While large RI panels are available for Arabidopsis, maize, C. elegans, and Drosophila, mouse RI panels typically consist of fewer than 30 lines. This is a severe constraint on the power and precision of mapping efforts and greatly hampers analysis of epistatic interactions. In order to address these limitations and to provide the community with a more effective collaborative RI mapping panel we generated new BXD RI strains from two independent advanced intercrosses (AI) between C57BL/6J (B6) and DBA/2J (D2) progenitor strains. Progeny were intercrossed for 9 to 14 generations before initiating inbreeding, which is still ongoing for some strains. Since this AI base population is highly recombinant, the 46 advanced recombinant inbred (ARI) strains incorporate approximately twice as many recombinations as standard RI strains, a fraction of which are inevitably shared by descent. When combined with the existing BXD RI strains, the merged BXD strain set triples the number of previously available unique recombinations and quadruples the total number of recombinations in the BXD background. The combined BXD strain set is the largest mouse RI mapping panel. It is a powerful tool for collaborative analysis of quantitative traits and gene function that will be especially useful to study variation in transcriptome and proteome data sets under multiple environments. Additional strains also extend the value of the extensive phenotypic characterization of the previously available strains. A final advantage of expanding the BXD strain set is that both progenitors have been sequenced, and approximately 1.8 million SNPs have been characterized. This provides unprecedented power in screening candidate genes and can reduce the effective length of QTL intervals. It also makes it possible to reverse standard mapping strategies and to explore downstream effects of known sequence variants.

Arachidonic acid status correlates with first year growth in preterm infants.

Abstract: Diets deficient in the omega-6 fatty acid linoleic acid reduce arachidonic acid (Ach) concentrations and retard growth of developing animals and humans Nevertheless, plasma phosphatidylcholine Ach concentrations declined from 84 +/- 23 mg/liter at birth to a nadir of 38 +/- 11 mg/liter at 4 mo of age in preterm infants fed commercial formulas with linoleic acid, and weight normalized to that of term infants fell progressively beginning at 2 mo of age The nadir of plasma phosphatidylcholine Ach (31 +/- 7 mg/liter) and growth were further reduced by formula containing marine oil compared with the commercial formulas Ach status (defined as the mean plasma phosphatidylcholine Ach concentration at 2, 4, and 65 mo) correlated with one or more measures of normalized growth through 12 mo Ach status and maternal height accounted for as much as 59% of the weight variance and 68% of the length variance in infants fed standard formulas Better Ach status was not from higher energy intakes A conditional Ach deficiency in preterm infants may contribute to growth over the first year of life On the strength of the relationship between Ach status and growth, we hypothesize that dietary Ach could improve first year growth of preterm infants

Sensing the Environment: Regulation of Local and Global Homeostasis by the Skin's Neuroendocrine System

Abstract: 1.1. General overview The strategic location of the skin as the barrier between the environment and internal milieu determines its critical function in the preservation of body homeostasis, and ultimately organism survival (Slominski, 2005, Slominski and Wortsman, 2000, Slominski et al., 2000c, Zmijewski and Slominski, 2011). It also exposes skin to numerous pathological agents, processes, and events. Thus, the capability to locally recognize, discriminate and integrate various signals within a highly heterogeneous environment, and to immediately launch appropriate responses, is a vital property of skin (Slominski and Wortsman, 2000). These skin functions are integrated into the skin immune, pigmentary, epidermal and adnexal systems, and are in continuous communication with the systemic immune, neural and endocrine systems (Arck et al., 2006, Slominski, 2009c, Slominski et al., 2004c, Slominski and Wortsman, 2000, Slominski et al., 2007a, Stenn and Paus, 2001). These fundamental functions results from the location of the skin, which is the largest body’s organ, at the interphase between external and internal environment, requiring development of efficient sensory and effector capabilities to differentially react to changes in external environment. They are represented by inducible production of biologically active compounds (hormones, neurohormones and neurotransmitters) that act both locally and at the systemic levels (Fig. 1). Figure 1 Skin senses changes in the environment through cutaneous neuroendocrine system, which computes and translates the received information into chemical, physical and biological messengers that regulate global (A and B) and local (B) homeostasis. These signals ... The skin being continuously exposed to many external biological or environmental factors (acute transfers of solar, thermal or chemical energy), had to evolve optimal mechanism(s) to protect, restore or maintain local and global homeostasis in relation to hostile environment (Slominski et al., 1993b, Slominski and Pawelek, 1998, Slominski and Wortsman, 2000, Slominski et al., 2000c). We have proposed that precise coordination and execution of these responses are mediated by a cutaneous neuroendocrine system, which also is able to reset the body homeostatic adaptation mechanisms (Slominski and Wortsman, 2000). Superimposed on this is the impact of psychological stress on skin physiology and pathology, placed in the context of the bidirectional brain-skin communication (Arck et al., 2006, Slominski, 2005a, Slominski et al., 2008b). To summarize, in reaction to changing external and also internal environment, the skin can generate signals to produce rapid (neural) or slow (humoral or immune) responses at the local and systemic levels (Fig. 1). Coordination between these local and systemic responses is mediated by the skin neuroendocrine system (Slominski and Wortsman, 2000a), which employs local equivalents of the hypothalamo-pituitary-adrenal axis (HPA) (Slominski et al., 2007a), hypothalamo-pituitary-thyroid (HPT) axis (Pisarchik and Slominski, 2002, van Beek et al., 2008), catecholaminergic (Schallreuter et al., 1997), serotoninergic, melatoninergic (Slominski et al., 2008a, Slominski et al., 2005c), cholinergic (Grando, 2006, Grando et al., 2006), steroidogenic (Slominski et al., 2008b) and secosteroidogenic (Bikle, 2010, Holick, 2003, Slominski et al., 2010) systems (Fig. 2). Given their common embryonic origins, it is not surprising that skin shares numerous mediators with the CNS and endocrine system. Recent research has revealed that skin also harbors a complex opioidogenic (Grando et al., 1995, Slominski et al., 2011c) and canabinnoidogenic (Biro et al., 2009) systems, which role in the maintenance of cutaneous homeostasis is currently being intensively explored. Figure 2 Skin neuroendocrine system follows the algorithms of classical neuroendocrine or endocrine systems. It also forms a natural platform of signal exchange between internal organs and environment. For this purpose skin cells not only are subjected to neurohormonal ... In this monograph we will discuss the role of various components of the skin neuroendocrine system in sensing the environment with subsequent regulation of local and global homeostasis with a main focus on the algorithms of classical neuroendocrine axes.

Ascorbic acid enhances tet-mediated 5-methylcytosine oxidation and promotes DNA demethylation in mammals

Abstract: DNA hydroxymethylation and its mediated DNA demethylation are critical for multiple cellular processes, for example, nuclear reprogramming, embryonic development, and many diseases. Here, we demonstrate that a vital nutrient ascorbic acid (AA), or vitamin C (Vc), can directly enhance the catalytic activity of Tet dioxygenases for the oxidation of 5-methylcytosine (5mC). As evidenced by changes in intrinsic fluorescence and catalytic activity of Tet2 protein caused by AA and its oxidation-resistant derivatives, we further show that AA can uniquely interact with the C-terminal catalytic domain of Tet enzymes, which probably promotes their folding and/or recycling of the cofactor Fe2+. Other strong reducing chemicals do not have a similar effect. These results suggest that AA also acts as a cofactor of Tet enzymes. In mouse embryonic stem cells, AA significantly increases the levels of all 5mC oxidation products, particularly 5-formylcytosine and 5-carboxylcytosine (by more than an order of magnitude), leadi...