Effects of IGF‐1 isoforms on muscle growth and sarcopenia

The decline in skeletal muscle mass and strength occurring in aging, referred as sarcopenia, is the result of many factors including an imbalance between protein synthesis and degradation, changes in metabolic/hormonal status, and in circulating levels of inflammatory mediators. Thus, factors that increase muscle mass and promote anabolic pathways might be of therapeutic benefit to counteract sarcopenia. Among these, the insulin‐like growth factor‐1 (IGF‐1) has been implicated in many anabolic pathways in skeletal muscle. IGF‐1 exists in different isoforms that might exert different role in skeletal muscle. Here we study the effects of two full propeptides IGF‐1Ea and IGF‐1Eb in skeletal muscle, with the aim to define whether and through which mechanisms their overexpression impacts muscle aging. We report that only IGF‐1Ea expression promotes a pronounced hypertrophic phenotype in young mice, which is maintained in aged mice. Nevertheless, examination of aged transgenic mice revealed that the local expression of either IGF‐1Ea or IGF‐1Eb transgenes was protective against age‐related loss of muscle mass and force. At molecular level, both isoforms activate the autophagy/lysosome system, normally altered during aging, and increase PGC1‐α expression, modulating mitochondrial function, ROS detoxification, and the basal inflammatory state occurring at old age. Moreover, morphological integrity of neuromuscular junctions was maintained and preserved in both MLC/IGF‐1Ea and MLC/IGF‐1Eb mice during aging. These data suggest that IGF‐1 is a promising therapeutic agent in staving off advancing muscle weakness.     

Effect of different growth hormone dosages on the growth velocity in children born small for gestational age

To assess whether short-term growth hormone (GH) treatment can improve the linear growth in children who were born small for gestational age (SGA), we started a randomized multicenter trial in 26 age- and sex-matched prepubertal children born SGA. During the 1st year of GH therapy, all children received GH 0.23 mg/kg/week, then during the 2nd year, 13 children received the same dose (group A), and in the other 13 children, the dose of GH was doubled, i.e., 0.46 mg/kg/week (group B). During the 1st year of therapy, the growth velocity significantly (p<0.0001) increased in all patients. During the 2nd year, group A showed a significant decrease of the growth velocity (p<0.015), whereas group B maintained the growth rate. The height in group A children significantly increased during the 1st and the 2nd year of GH therapy (p<0.000002 and p<0.000001, respectively), reaching the normal range in 8 out of 13 children at the end of 2 years of GH therapy. The height in group B children significantly increased during the 1st and the 2nd year of GH therapy (p<0.000001 and p<0.000001, respectively), reaching the normal range in all 11 children who completed the GH therapy. The height gain was similar in groups A and B treated with the same GH dosage during the 1st year of therapy. A greater increase in height gain was found in children of group B treated with the higher GH dosage during the 2nd year of therapy as compared with group A (p<0.02). Significant increases in insulin-like growth factor I (p<0.0001), acid-labile subunit (p<0.0002), and bone/chronological age ratio (p<0.0001) were found after the 1st year of GH therapy, but no significant changes were observed during the 2nd year, independently of the GH dose. In conclusion, the height velocity of children born SGA significantly increases during the 1st year of GH therapy, diminishes, but can decrease during the 2nd year, if the GH dosage is not raised.     

Annual variations of adrenal gland hormones in the lizard <Emphasis Type="Italic">Podarcis sicula</Emphasis>

The adrenal gland regulates metabolism and maintains normal electrolyte balance. Adrenal hormones are equivalent in all vertebrates; the chromaffin tissue produces adrenaline and noradrenaline and the steroidogenic tissue produces most of the steroid hormones present in mammals. Podarcis sicula belongs to the Squamata family of lizards and it is the most abundant lizard species in southern Italy. This species shows a reproductive annual cycle and the presence of seasonal variations in the activity of the hypothalamus-hypophyseal-thyroid axis. To investigate the existence of an annual cycle of lizard adrenal gland, we have measured plasma concentrations of corticosterone, ACTH, noradrenaline and adrenaline. We have shown that corticosterone rapidly increased from January to March to reach a peak value that persisted until July, then, it slowly decreased until December. ACTH levels increased from January to May and slowly decreased from July to December. Noradrenaline levels were higher in March and then decreased until December. On the contrary, adrenaline levels increased from March to July and slowly decreased until December. Our results demonstrate the existence of an annual cycle of the lizard adrenal gland activity. This is very interesting because its activity is important to rightly regulate the reproductive status of the Podarcis sicula lizard.     

Test–Retest Reliability of Static EMG Scan Configural Profiling

Measurement techniques or instruments are typically evaluated along the dimensions of reliability and validity. The focus of this investigation was to assess the test–retest reliability of a static EMG scan profile (sESP) method using 64 chronic pain participants. The test–retest interval was 30–33 days. Reliability coefficients were expressed using the Profile Similarity Coefficient (r _p) in place of the more traditional Pearson Product Moment Correlation. sESP reliabilities were calculated for posture laterality for the head and neck, back, and overall profiles (head, neck, and back combined). The reliability coefficients ranged from .57 to .80. The back profile was the least reliable with a range of .55–.59 whereas the overall profiles were the most reliable, .78–.80. The analysis method was judged to be very conservative with its use of r _p, a protracted intertest interval period, and weighting the data by their variances. These results can be viewed as setting the lower reliability limit for sESP.     

Infarct-induced chronic heart failure increases bidirectional protein movement across the alveolocapillary barrier

Chronic heart failure (CHF) is associated with adaptive structural changes at the alveolocapillary barrier that may be associated with altered protein permeability. Bidirectional protein movement across the barrier was studied in anesthetized rats with infarct-induced CHF by following (125)I-labeled albumin ((125)I-albumin) flux into the alveoli and the leakage of surfactant protein (SP)-B from the alveoli into the circulation. Three groups were studied: controls [0% left ventricular (LV) infarction], moderate infarct (25-45% LV infarction), and large infarct (>46% LV infarction). Wet and dry lung weights increased in the large infarct group (both P < 0.001), consistent with increased lung water and solid lung tissue. (125)I-albumin flux increased across the endothelial (P < 0.001) and epithelial (P < 0.01) components of the alveolocapillary barrier in the large infarct group. Plasma SP-B increased 23% with moderate infarcts (P < 0.05) and 97% with large infarcts (P < 0.001), independent of alveolar levels. Lavage fluid immune cells (P < 0.01) and myeloperoxidase activity (P < 0.05) increased in the large infarct group, consistent with inflammation. Bidirectional protein movement across the alveolocapillary barrier is increased in CHF, and alveolar inflammation may contribute to this pathophysiological defect.     

Nodal-dependent Cripto signaling promotes cardiomyogenesis and redirects the neural fate of embryonic stem cells

The molecular mechanisms controlling inductive events leading to the specification and terminal differentiation of cardiomyocytes are still largely unknown. We have investigated the role of Cripto, an EGF-CFC factor, in the earliest stages of cardiomyogenesis. We find that both the timing of initiation and the duration of Cripto signaling are crucial for priming differentiation of embryonic stem (ES) cells into cardiomyocytes, indicating that Cripto acts early to determine the cardiac fate. Furthermore, we show that failure to activate Cripto signaling in this early window of time results in a direct conversion of ES cells into a neural fate. Moreover, the induction of Cripto activates the Smad2 pathway, and overexpression of activated forms of type I receptor ActRIB compensates for the lack of Cripto signaling in promoting cardiomyogenesis. Finally, we show that Nodal antagonists inhibit Cripto-regulated cardiomyocyte induction and differentiation in ES cells. All together our findings provide evidence for a novel role of the Nodal/Cripto/Alk4 pathway in this process.     

HPLC analysis of fusaric acid, 9,10-dehydrofusaric acid and their methyl esters,toxic metabolites from weed pathogenic Fusarium species

A simple and rapid HPLC method, using a high-density C18 column, has been developed for the quantitative analysis of fusaric and dehydrofusaric acids and their methyl esters in the methanol extract of lyophilised culture filtrates of species of Fusarium. The method has been used to determine the content of these metabolites in two strains of Fusarium oxysporum and in strains of F. nygamai and F. udum. Fusaric acid has been isolated and identified from a strain of F. udum for the first time.     

Glutathione transferase isoenzymes from frog (Xenopus laevis) liver and embryo

The expression of glutathione transferase isoenzymes has been investigated in embryo and adult liver of the frog Xenopus laevis. By analysing the GST isoenzymes recovered from GSH-affinity chromatography in terms of electrophoretic mobility, HPLC elution profile, immunological reactivity, N-terminal amino acid sequence and mass spectrometry molecular mass no significant difference in the GST subunit composition between embryos and liver was found. In both tissues the same three subunits, showing similarity to mu, alpha and sigma class GSTs, are present. These results, together with those previously reported for toad (Bufo bufo), strongly support the notion that the transition from an aquatic environment to a terrestrial atmosphere containing high oxygen concentration has accompanied specific GST gene expression.     

Identification of sequence motifs responsible for the adhesive interaction between exon v10-containing CD44 isoforms

Previous studies have demonstrated that CD44 isoforms containing the alternatively spliced exon v10 promote cell-cell adhesion via a mechanism that involves the recognition of chondroitin sulfate side chains presented on the surface of interacting cells in association with other CD44 molecules. Sequence analysis revealed the presence within exon v10 of two motifs that may be relevant to this interaction, a B[X(7)]B motif that may contribute to the recognition and binding of chondroitin sulfate and a serine-glycine motif that may serve as a site of chondroitin sulfate attachment. To determine whether either of these two motifs explain the unique adhesive activity of exon v10-containing CD44 isoforms, each was targeted by site-directed mutagenesis, and the adhesive activity of the resultant mutants was determined using a quantitative cell-cell binding assay. The data obtained demonstrate conclusively that it is the exon v10-encoded B[X(7)]B motif that is solely responsible for the enhanced adhesive activity of exon v10-containing CD44 isoforms.     

Melusin,a muscle-specific integrin beta1-interacting protein,is required to prevent cardiac failure in response to chronic pressure overload

Cardiac hypertrophy is an adaptive response to a variety of mechanical and hormonal stimuli, and represents an early event in the clinical course leading to heart failure. By gene inactivation, we demonstrate here a crucial role of melusin, a muscle-specific protein that interacts with the integrin beta1 cytoplasmic domain, in the hypertrophic response to mechanical overload. Melusin-null mice showed normal cardiac structure and function in physiological conditions, but when subjected to pressure overload--a condition that induces a hypertrophic response in wild-type controls--they developed an abnormal cardiac remodeling that evolved into dilated cardiomyopathy and contractile dysfunction. In contrast, the hypertrophic response was identical in wild-type and melusin-null mice after chronic administration of angiotensin II or phenylephrine at doses that do not increase blood pressure--that is, in the absence of cardiac biomechanical stress. Analysis of intracellular signaling events induced by pressure overload indicated that phosphorylation of glycogen synthase kinase-3beta (GSK-3beta) was specifically blunted in melusin-null hearts. Thus, melusin prevents cardiac dilation during chronic pressure overload by specifically sensing mechanical stress.