Running a Marathon Induces Changes in Adipokine Levels and in Markers of Cartilage Degradation – Novel Role for Resistin

Running a marathon causes strenuous joint loading and increased energy expenditure. Adipokines regulate energy metabolism, but recent studies have indicated that they also exert a role in cartilage degradation in arthritis. Our aim was to investigate the effects of running a marathon on the levels of adipokines and indices of cartilage metabolism. Blood samples were obtained from 46 male marathoners before and after a marathon run. We measured levels of matrix metalloproteinase-3 (MMP-3), cartilage oligomeric protein (COMP) and chitinase 3-like protein 1 (YKL-40) as biomarkers of cartilage turnover and/or damage and plasma concentrations of adipokines adiponectin, leptin and resistin. Mean marathon time was 3∶30∶46±0∶02∶46 (h:min:sec). The exertion more than doubled MMP-3 levels and this change correlated negatively with the marathon time (r = –0.448, p = 0.002). YKL-40 levels increased by 56% and the effect on COMP release was variable. Running a marathon increased the levels of resistin and adiponectin, while leptin levels remained unchanged. The marathon-induced changes in resistin levels were positively associated with the changes in MMP-3 (r = 0.382, p = 0.009) and YKL-40 (r = 0.588, p<0.001) and the pre-marathon resistin levels correlated positively with the marathon induced change in YKL-40 (r = 0.386, p = 0.008). The present results show the impact of running a marathon, and possible load frequency, on cartilage metabolism: the faster the marathon was run, the greater was the increase in MMP-3 levels. Further, the results introduce pro-inflammatory adipocytokine resistin as a novel factor, which enhances during marathon race and associates with markers of cartilage degradation.     

Crosstalk between Jagged1 and GDNF/Ret/GFRalpha1 signalling regulates ureteric budding and branching

Glial-Cell-Line-Derived Neurotrophic Factor (GDNF) is the major mesenchyme-derived regulator of ureteric budding and branching during nephrogenesis. The ligand activates on the ureteric bud epithelium a receptor complex composed of Ret and GFRalpha1. The upstream regulators of the GDNF receptors are poorly known. A Notch ligand, Jagged1 (Jag1), co-localises with GDNF and its receptors during early kidney morphogenesis. In this study we utilized both in vitro and in vivo models to study the possible regulatory relationship of Ret and Notch pathways. Urogenital blocks were exposed to exogenous GDNF, which promotes supernumerary ureteric budding from the Wolffian duct. GDNF-induced ectopic buds expressed Jag1, which suggests that GDNF can, directly or indirectly, up-regulate Jag1 through Ret/GFRalpha1 signalling. We then studied the role of Jag1 in nephrogenesis by transgenic mice constitutively expressing human Jag1 in Wolffian duct and its derivatives under HoxB7 promoter. Jag1 transgenic mice showed a spectrum of renal defects ranging from aplasia to hypoplasia. Ret and GFRalpha1 are normally downregulated in the Wolffian duct, but they were persistently expressed in the entire transgenic duct. Simultaneously, GDNF expression remained unexpectedly low in the metanephric mesenchyme. In vitro, exogenous GDNF restored the budding and branching defects in transgenic urogenital blocks. Renal differentiation apparently failed because of perturbed stimulation of primary ureteric budding and subsequent branching. Thus, the data provide evidence for a novel crosstalk between Notch and Ret/GFRalpha1 signalling during early nephrogenesis.     

Antiarrhythmic Effects of Dantrolene in Patients with Catecholaminergic Polymorphic Ventricular Tachycardia and Replication of the Responses Using iPSC Models

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a highly malignant inherited arrhythmogenic disorder. Type 1 CPVT (CPVT1) is caused by cardiac ryanodine receptor (RyR2) gene mutations resulting in abnormal calcium release from sarcoplasmic reticulum. Dantrolene, an inhibitor of sarcoplasmic Ca²⁺ release, has been shown to rescue this abnormal Ca²⁺ release in vitro. We assessed the antiarrhythmic efficacy of dantrolene in six patients carrying various RyR2 mutations causing CPVT. The patients underwent exercise stress test before and after dantrolene infusion. Dantrolene reduced the number of premature ventricular complexes (PVCs) on average by 74% (range 33-97) in four patients with N-terminal or central mutations in the cytosolic region of the RyR2 protein, while dantrolene had no effect in two patients with mutations in or near the transmembrane domain. Induced pluripotent stem cells (iPSCs) were generated from all the patients and differentiated into spontaneously beating cardiomyocytes (CMs). The antiarrhythmic effect of dantrolene was studied in CMs after adrenaline stimulation by Ca²⁺ imaging. In iPSC derived CMs with RyR2 mutations in the N-terminal or central region, dantrolene suppressed the Ca²⁺ cycling abnormalities in 80% (range 65-97) of cells while with mutations in or near the transmembrane domain only in 23 or 32% of cells. In conclusion, we demonstrate that dantrolene given intravenously shows antiarrhythmic effects in a portion of CPVT1 patients and that iPSC derived CM models replicate these individual drug responses. These findings illustrate the potential of iPSC models to individualize drug therapy of inherited diseases.

Trial Registration

EudraCT Clinical Trial Registry 2012-005292-14     

Ghrelin induces vasoconstriction in the rat coronary vasculature without altering cardiac peptide secretion

We administered ghrelin, a novel growth hormone-releasing hormone, to isolated perfused rat hearts, coronary arterioles, and cultured neonatal cardiomyocytes to determine its effects on coronary vascular tone, contractility, and natriuretic peptide secretion and gene expression. We also determined cardiac levels of ghrelin and whether the heart is a source of the circulating peptide. Ghrelin dose dependently increased coronary perfusion pressure (44 +/- 9%, P < 0.01), constricted isolated coronary arterioles (12 +/- 2%, P < 0.05), and significantly enhanced the pressure-induced myogenic tone of arterioles. These effects were blocked by diltiazem, an L-type Ca(2+) channel blocker, and bisindolylmaleimide (Bis), a protein kinase C (PKC) inhibitor. Interestingly, coinfusion of ghrelin with diltiazem completely restored myocardial contractile function that was decreased 30 +/- 3% (P < 0.01) by diltiazem alone. In contrast, combination of ghrelin with diltiazem or Bis did not significantly alter atrial natriuretic peptide (ANP) secretion, which was decreased 40% (P < 0.01) and 50% (P < 0.05) by these agents alone, respectively. Administration of ghrelin to cultured cardiomyocytes had no effect on ANP or B-type natriuretic peptide secretion or gene expression. Detectable amounts of low-molecular-weight ghrelin were present in cardiac tissue extracts but not in isolated heart perfusate. Thus we provide the first evidence that ghrelin has a coronary vasoconstrictor action that is dependent on Ca(2+) and PKC. Furthermore, the data obtained from diltiazem infusion suggest that ghrelin has a role in regulation of contractility when L-type Ca(2+) channels are blocked. Finally, the observation that immunoreactive ghrelin is found in cardiac tissue suggests the presence of a local cardiac ghrelin system.     

Attributions of Cancer ‘Alarm’ Symptoms in a Community Sample

BackgroundAttribution of early cancer symptoms to a non-serious cause may lead to longer diagnostic intervals. We investigated attributions of potential cancer ‘alarm’ and non-alarm symptoms experienced in everyday life in a community sample of adults, without mention of a cancer context.MethodsA questionnaire was mailed to 4858 adults (≥50 years old, no cancer diagnosis) through primary care, asking about symptom experiences in the past 3 months. The word cancer was not mentioned. Target ''alarm'' symptoms, publicised by Cancer Research UK, were embedded in a longer symptom list. For each symptom experienced, respondents were asked for their attribution (‘what do you think caused it''), concern about seriousness (‘not at all’ to ‘extremely’), and help-seeking (‘did you contact a doctor about it’: Yes/No).ResultsThe response rate was 35% (n = 1724). Over half the respondents (915/1724; 53%) had experienced an ‘alarm’ symptom, and 20 (2%) cited cancer as a possible cause. Cancer attributions were highest for ‘unexplained lump’; 7% (6/87). Cancer attributions were lowest for ‘unexplained weight loss’ (0/47). A higher proportion (375/1638; 23%) were concerned their symptom might be ‘serious’, ranging from 12% (13/112) for change in a mole to 41% (100/247) for unexplained pain. Just over half had contacted their doctor about their symptom (59%), although this varied by symptom. Alarm symptoms were appraised as more serious than non-alarm symptoms, and were more likely to trigger help-seeking.ConclusionsConsistent with retrospective reports from cancer patients, ‘alarm’ symptoms experienced in daily life were rarely attributed to cancer. These results have implications for understanding how people appraise and act on symptoms that could be early warning signs of cancer.     

The gene encoding human low-molecular weight insulin-like growth-factor binding protein (IGF-BP25): regional localization to 7p12–p13 and description of a DNA polymorphism

The low-molecular weight insulin-like growth-factor binding protein (IGF-BP25) is synthesized by human liver, secretory endometrium and decidua, and is also present in human serum. It binds insulin-like growth factors IGF-I and IGF-II with high affinity, and is proposed to act as a paracrine regulator of cell growth. In situ hybridization studies with a cDNA encompassing the entire protein coding region of IGF-BP25 localized the gene to bands p12-p13 on chromosome 7. Southern blot analysis with the enzyme BglII revealed a common restriction fragment length polymorphism: the presence of the polymorphic BglII site results in the formation of two fragments 4.6 kb and 1.6 kb in size whereas its absence produces a single 6.2 kb fragment. The frequencies of the two alleles were 0.73 and 0.27, respectively. IGF-BP25 constitutes a useful genetic marker for the proximal short arm of chromosome 7.     

Mutation in TERMINAL FLOWER1 reverses the photoperiodic requirement for flowering in the wild strawberry Fragaria vesca

Photoperiodic flowering has been extensively studied in the annual short-day and long-day plants rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana), whereas less is known about the control of flowering in perennials. In the perennial wild strawberry, Fragaria vesca (Rosaceae), short-day and perpetual flowering long-day accessions occur. Genetic analyses showed that differences in their flowering responses are caused by a single gene, SEASONAL FLOWERING LOCUS, which may encode the F. vesca homolog of TERMINAL FLOWER1 (FvTFL1). We show through high-resolution mapping and transgenic approaches that FvTFL1 is the basis of this change in flowering behavior and demonstrate that FvTFL1 acts as a photoperiodically regulated repressor. In short-day F. vesca, long photoperiods activate FvTFL1 mRNA expression and short days suppress it, promoting flower induction. These seasonal cycles in FvTFL1 mRNA level confer seasonal cycling of vegetative and reproductive development. Mutations in FvTFL1 prevent long-day suppression of flowering, and the early flowering that then occurs under long days is dependent on the F. vesca homolog of FLOWERING LOCUS T. This photoperiodic response mechanism differs from those described in model annual plants. We suggest that this mechanism controls flowering within the perennial growth cycle in F. vesca and demonstrate that a change in a single gene reverses the photoperiodic requirements for flowering.     

Overexpression of sarcolemmal calcium pump attenuates induction of cardiac gene expression in response to ET-1

The function of the plasma membrane calmodulin-dependent calcium ATPase (PMCA) in myocardium is unknown. PMCA is localized in caveolae, 50- to 100-nm membrane invaginations, which also contain receptors for endothelin-1 (ET-1) and various other ligands. PMCA has been suggested to play a role in regulation of caveolar signal transduction. We studied the effects of the hypertrophic agonist ET-1 and increased coronary perfusion pressure on cardiac synthesis of B-type natriuretic peptide (BNP) in transgenic rats overexpressing the human PMCA 4CI in isolated perfused heart preparation. ET-1 infusion for 2 h increased BNP mRNA levels twofold in left ventricles (LV) of nontransgenic rats, whereas no increase was noted in PMCA rat hearts. Similar responses were seen in adrenomedullin and c-fos mRNA levels, and in immunoreactive BNP secretion. Increased mechanical load produced by elevated perfusion pressure induced similar 1.5- to 1.6-fold increases in LV BNP mRNA in both nontransgenic and PMCA rat hearts. These results show that cardiac overexpression of PMCA attenuates ET-1-stimulated early induction of cardiac gene expression, suggesting that PMCA may modulate myocardial growth responses.     

Utility of plasma apelin and other indices of cardiac dysfunction in the clinical assessment of patients with dilated cardiomyopathy

Apelin is a recently discovered peptide ligand reported to be involved in the regulation of cardiovascular homeostasis. The exact role of apelin in the pathophysiology of congestive heart failure has remained obscure, and the reported circulating levels of apelin in patients with heart failure have been contradictory. To establish the role of apelin in the assessment of cardiac dysfunction we measured plasma apelin levels in 65 patients with congestive heart failure caused by idiopathic dilated cardiomyopathy (IDC) and 14 healthy volunteers by specific radioimmunoassay. IDC patients were carefully examined including echocardiography, both-sided cardiac catheterization and cardiopulmonary exercise test. In addition, plasma levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), N-terminal pro-atrial natriuretic peptide (NT-proANP), interleukin (IL)-6, tumor necrosis factor alpha (TNF-), epinephrine and norepinephrine were determined. Plasma apelin levels were similar in IDC patients (median 26.5 pg/ml, range < 3.40–97.6 pg/ml) and in control subjects (median 24.1 pg/ml, range 19.0–28.7 pg/ml; p = NS). Unlike the levels of NT-proBNP, IL-6, TNF-, and norepinephrine, plasma apelin levels did not reflect the severity of heart failure. Our study demonstrates that although disturbed apelin–APJ signalling in heart may play a role in the pathophysiology of heart failure, circulating apelin levels cannot be applied in the clinical assessment of patients with chronic left ventricular dysfunction.