Collagen Gene Polymorphisms Previously Associated with Resistance to Soft-Tissue Injury Are More Common in Competitive Runners Than Nonathletes.

ABSTRACT: Dines, HR, Nixon, J, Lockey, SJ, Herbert, AJ, Kipps, C, Pedlar, CR, Day, SH, Heffernan, SM, Antrobus, MR, Brazier, J, Erskine, RM, Stebbings, GK, Hall, ECR, and Williams, AG. Collagen gene polymorphisms previously associated with resistance to soft-tissue injury are more common in competitive runners than nonathletes. J Strength Cond Res 37(4): 799-805, 2023-Single-nucleotide polymorphisms (SNPs) of collagen genes have been associated with soft-tissue injury and running performance. However, their combined contribution to running performance is unknown. We investigated the association of 2 collagen gene SNPs with athlete status and performance in 1,429 Caucasian subjects, including 597 competitive runners (354 men and 243 women) and 832 nonathletes (490 men and 342 women). Genotyping for COL1A1 rs1800012 (C > A) and COL5A1 rs12722 (C > T) SNPs was performed by a real-time polymerase chain reaction. The numbers of "injury-resistant" alleles from each SNP, based on previous literature (rs1800012 A allele and rs12722 C allele), were combined as an injury-resistance score (RScore, 0-4; higher scores indicate injury resistance). Genotype frequencies, individually and combined as an RScore, were compared between cohorts and investigated for associations with performance using official race times. Runners had 1.34 times greater odds of being rs12722 CC homozygotes than nonathletes (19.7% vs. 15.5%, p = 0.020) with no difference in the rs1800012 genotype distribution ( p = 0.659). Fewer runners had an RScore 0 of (18.5% vs. 24.7%) and more had an RScore of 4 (0.6% vs. 0.3%) than nonathletes ( p < 0.001). Competitive performance was not associated with the COL1A1 genotype ( p = 0.933), COL5A1 genotype ( p = 0.613), or RScore ( p = 0.477). Although not associated directly with running performance among competitive runners, a higher combined frequency of injury-resistant COL1A1 rs1800012 A and COL5A1 rs12722 C alleles in competitive runners than nonathletes suggests these SNPs may be advantageous through a mechanism that supports, but does not directly enhance, running performance.

Impact of high-dose inotropic donor support on early myocardial necrosis and outcomes in cardiac transplantation.

BACKGROUND: Cardiac donors routinely require vasoactive agents for circulatory stability after brain death. Nevertheless, inotropes have been associated with direct cardiac toxicity. Our study evaluated whether the use of high-dose inotropic support in potential donors was associated with increased early myocardial necrosis (MN) and worse clinical outcomes after cardiac transplantation. METHODS: The UTAH Cardiac Transplant Program (UCTP) and Intermountain Donor Services databases were queried for records between 1996 and 2009. The high-dose donor inotropic support (HDIS) group was defined as patients on dopamine >10 µg/kg/min. The incidence of early MN, intensive care unit (ICU) length of stay, length of ventilator support, and mortality was evaluated. RESULTS: Two hundred and forty-four recipients undergoing transplant met study criteria. The average donor age was 27 yr. The incidence of MN in the HDIS (n=29) and non-HDIS (n=204) groups was 14.8% and 6.7%, respectively, OR 2.67. Total ischemic time, ventilator support time, ICU stay, and actuarial survival were similar between both groups. CONCLUSION: The use of high-dose inotropic support to maintain donor stability appears to have a higher trend for early post-transplant MN without an impact on clinical outcomes. With the current growing shortage of organ donors, it appears reasonable to use donors on high-dose inotropic support.

Dimerization of protein tyrosine phosphatase sigma governs both ligand binding and isoform specificity.

Signaling through receptor protein tyrosine phosphatases (RPTPs) can influence diverse processes, including axon development, lymphocyte activation, and cell motility. The molecular regulation of these enzymes, however, is still poorly understood. In particular, it is not known if, or how, the dimerization state of RPTPs is related to the binding of extracellular ligands. Protein tyrosine phosphatase sigma (PTPsigma) is an RPTP with major isoforms that differ in their complements of fibronectin type III domains and in their ligand-binding specificities. In this study, we show that PTPsigma forms homodimers in the cell, interacting at least in part through the transmembrane region. Using this knowledge, we provide the first evidence that PTPsigma ectodomains must be presented as dimers in order to bind heterophilic ligands. We also provide evidence of how alternative use of fibronectin type III domain complements in two major isoforms of PTPsigma can alter the ligand binding specificities of PTPsigma ectodomains. The data suggest that the alternative domains function largely to change the rotational conformations of the amino-terminal ligand binding sites of the ectodomain dimers, thus imparting novel ligand binding properties. These findings have important implications for our understanding of how heterophilic ligands interact with, and potentially regulate, RPTPs.

PTPsigma binds and dephosphorylates neurotrophin receptors and can suppress NGF-dependent neurite outgrowth from sensory neurons.

Neurotrophin receptors of the Trk family play a vital role in the survival of developing neurons and the process of axonogenesis. The Trk family are receptor protein tyrosine kinases (RTKs) and their signalling in response to neurotrophins is critically dependent upon their ability to transphosphorylate and act as signalling centres for multiple adaptor proteins and distinct, downstream pathways. Such phosphotyrosine signalling also depends upon the appropriate counter-regulation by phosphatases. A large family of receptor-like protein tyrosine phosphatases (RPTPs) are also expressed in developing neurons and in this study we have examined the ability of the phosphatase PTPsigma to interact with and regulate Trk proteins in transfected HEK 293T cells. PTPsigma can bind differentially to Trk proteins, binding stably in complexes with TrkA and TrkC, but not TrkB. The transmembrane domains of PTPsigma and TrkA appear to be sufficient for the direct or indirect interaction between these two receptors. Furthermore, PTPsigma is shown to dephosphorylate all three Trk receptors and suppress their phosphorylation in the presence of neurotrophins. In addition, overexpression of PTPsigma in primary sensory neurons in culture inhibits neurite outgrowth without affecting the short-term survival of these neurons. PTPsigma can thus show differential complex formation with different Trk family members and in neurons can selectively target the neurite-forming signalling pathway driven by TrkA.

Lactic acidosis after cardiac transplantation: foe or common innocent bystander?

BACKGROUND: Lactic acidosis (LA) frequently occurs after heart transplantation (HTx). It is hypothesized to be related to inotropic support or metabolic derangements from chronic heart failure. As such, restoring hemodynamic stability with mechanical circulatory support before HTx should mitigate this problem. Our aim was to evaluate the incidence and outcomes of LA after HTx. METHODS: We evaluated HTx recipients January 2000 to May 2011. Post-HTx outcomes included graft dysfunction, length of intensive care unit stay, length of hospital stay, inotropic support, and survival. RESULTS: Of 143 eligible patients, 98.6% had LA, 67% severe, after HTx. Data were analyzed based on the severity of LA. Time to peak lactate, intensive care unit stay, length of hospital stay, peak glucose, inotropic dose, graft dysfunction, and survival after HTx were similar between groups. Statistically significant differences included pretransplant support (25.6% mechanical circulatory support in nonsevere vs. 44.9% severe LA), hospitalization at the time of HTx (37.2% vs. 21.4%), glucose at the time of peak lactate (182.88 ± 69.80 vs. 221.31 ± 56.91), ischemic time (187.4 ± 63.1 vs. 215.5 ± 68.1), and duration of inotrope. CONCLUSION: Severe LA is common after HTx, though it appears to be transient and benign. Mechanical circulatory support after HTx does not prevent LA. High lactate levels are associated with longer ischemic times, longer duration of inotrope, and correspond with higher glucose levels. The underlying mechanism is yet to be satisfactorily elucidated.

15-Lipoxygenase-1 has anti-tumorigenic effects in colorectal cancer.

The localization of 15-lipoxygenase-1 (15-LO-1) in human colorectal carcinoma and normal adjacent tissue was examined using immunohistochemistry. In normal tissues, 15-LO-1 was strongly localized in the mucosal epithelium. Conversely, in tumor tissues, staining for 15-LO-1 was dispersed throughout the tissue, weak in neoplastic epithelium, and strong in stromal inflammatory cells. The addition of 50 microM 13(S)-hydroxyeicosatetraenoic acid (HODE), resulted in decreased cell proliferation after 72 h, but lower concentrations (5 or 10 microM) had no effect compared to vehicle treated Caco-2 cells. In addition, 13(S)-HODE had no effect on apoptosis or differentiation of the Caco-2 cells. Microarray analyses of RNA from Caco-2 cells treated with 5 microM 13(S)-HODE revealed changes in 17 genes. HCT-116 colorectal cells were stably transfected with 15-LO-1. In athymic nude mice, transplantable tumors derived from 15-LO-1 HCT-116 cells were smaller than tumors derived from vector HCT-116 cells. These data demonstrate that 13(S)-HODE induces changes in gene expression and has anti-tumorigenic effects.

Production and characterization of a novel human recombinant alpha-1-antitrypsin in PER.C6 cells.

Alpha-1-antitrypsin (A1PI) is a proteinase inhibitor of the serpin superfamily and circulates in plasma at about 1-2 g/L. A1PI deficiency in humans often results in organ damage, particularly to the lungs and liver. Current augmentation therapies rely entirely on A1PI isolated from human plasma, thus prompting an evaluation of alternate sources. We have co-expressed recombinant A1PI and α-2,3-sialyltransferase in the human cell line, PER.C6. The requirement for sialyltransferase overexpression in PER.C6 and the essential contribution of sialic acid glycan capping on pdA1PI and recA1PI to prevent rapid A1PI plasma elimination is shown. Using assays to predict high levels of A1PI production and sialylation, stably transfected PER.C6 cells were screened through two rounds of cell cloning to ensure monoclonality. Fed-batch culturing was used to evaluate recA1PI production and cell line characteristics, identifying subclones expressing over 2.5 g/L recA1PI. Cell stability was assessed over 50 generations, verifying subclone stability during continuous culture. Finally, data are presented showing that recA1PI and pdA1PI are equivalent in their ability to block elastase activity in functional cell-based assays and their pharmacokinetic properties. These data show that recombinant human A1PI recovered from PER.C6 cells offers a reliable source of functionally active A1PI for augmentation therapies and, potentially, other diseases.

Diallyl disulfide (DADS) induces the antitumorigenic NSAID-activated gene (NAG-1) by a p53-dependent mechanism in human colorectal HCT 116 cells.

Garlic is appealing as an anti-carcinogenic agent due to its ability to induce apoptosis in vitro and inhibit the formation and growth of tumors in animals in vivo. Diallyl disulfide (DADS) is a constituent of garlic that suppresses neoplastic cell growth and induces apoptosis. We examined the effects of DADS on various cancer cell lines to better understand its effect on apoptosis and apoptosis-related genes. The nonsteroidal anti-inflammatory drug (NSAID)-activated gene (NAG-1) has proapoptotic and antitumorigenic activities and is upregulated by anticancer agents such as NSAIDs. In this study, human colorectal HCT-116 (wild-type p53), HCT-15 (p53 mutant) and human prostate PC-3 (p53 mutant) cells were exposed to DADS. DADS inhibited cell proliferation in all cell lines albeit to a lesser extent in HCT-15 and PC-3 cells at 11.5 and 23 micromol/L. In HCT-116 cells, DADS induced p53 and NAG-1 in a dose-dependent manner and the induction of p53 preceded that of NAG-1. In HCT-116 cells, NAG-1 protein expression was increased 2.4-fold +/- 0.6 at 4.6 micromol/L and 6.1-fold +/- 1.7 at 23 micromol/L DADS, whereas p53 was induced 1.5-fold +/- 0.1 and 2.3-fold +/- 0.4. DADS did not induce NAG-1 or p53 in p53 mutant cell lines; however, NAG-1 expression was induced by sulindac sulfide. HCT-116 cells treated with 4.6 and 23 micromol/L DADS resulted in a 1.9- and 2.9-fold increase in apoptosis, respectively. In contrast, 23 micromol/L DADS induced apoptosis only 1.8-fold in HCT-15 cells and not at all in PC-3 cells. Thus, DADS-induced apoptosis and NAG-1 protein expression appear to occur via p53.

Expression of NAG-1, a transforming growth factor-beta superfamily member, by troglitazone requires the early growth response gene EGR-1.

Troglitazone (TGZ) and 15-deoxy-Delta(12,14)-prostaglandin J2 (PGJ2) are peroxisome proliferator-activated receptor-gamma (PPARgamma) ligands that have been shown to possess pro-apoptotic activity in human colon cancer. Although these compounds bind to PPARgamma transcription factors as agonists, emerging evidence suggests that TGZ acts independently of PPARgamma in many functions, including apoptosis. We previously reported that TGZ induces an early growth response transcription factor (EGR-1) by the ERK phosphorylation pathway rather than by the PPARgamma pathway (Baek, S. J., Wilson, L. C., Hsi, L. C., and Eling, T. E. (2003) J. Biol. Chem. 278, 5845-5853). In this report, we show that the expression of the antitumorigenic and/or pro-apoptotic gene NAG-1 (nonsteroidal anti-inflammatory drug-activated gene-1) is induced by TGZ and correlates with EGR-1 induction. In cotransfection and gel shift assays, we show that EGR-1-binding sites are located within region -73 to -51 of the NAG-1 promoter and have an important role in the transactivation of TGZ-induced NAG-1 expression. In contrast, PGJ2 induced NAG-1 protein expression, but PGJ2 may not affect the same region that TGZ does in the NAG-1 promoter. The effect of PGJ2 is probably PPARgamma-dependent because a PPARgamma antagonist inhibited the PGJ2-induced expression of NAG-1. TGZ-induced NAG-1 expression was not inhibited by the PPARgamma antagonist. The fact that TGZ-induced NAG-1 expression was accompanied by the biosynthesis of EGR-1 also suggests that EGR-1 plays a pivotal role in TGZ-induced NAG-1 expression. Our results suggest that EGR-1 induction is a unique property of TGZ, but is independent of PPARgamma activation. The up-regulation of NAG-1 may provide a novel explanation for the antitumorigenic property of TGZ.