Is mass loss along the red giant branch of globular clusters sharply peaked? The case of M3

There is a growing evidence that several globular clusters must contain multiple stellar generations, differing in helium content. This hypothesis has helped to interpret peculiar unexplained features in their horizontal branches. In this framework we model the peaked distribution of the RR Lyr periods in M3, that has defied explanation until now. At the same time, we try to reproduce the colour distribution of M3 horizontal branch stars. We find that only a very small dispersion in mass loss along the red giant branch reproduces with good accuracy the observational data. The enhanced and variable helium content among cluster stars is at the origin of the extension in colour of the horizontal branch, while the sharply peaked mass loss is necessary to reproduce the sharply peaked period distribution of RR Lyr variables. The dispersion in mass loss has to be <~ 0.003 Msun, to be compared with the usually assumed values of ~0.02 Msun. This requirement represents a substantial change in the interpretation of the physical mechanisms regulating the evolution of globular cluster stars.Comment: Accepted for publication in The Astrophysical Journa

Transcriptional Regulation of the Mitochondrial Citrate and Carnitine/Acylcarnitine Transporters: Two Genes Involved in Fatty Acid Biosynthesis and E-oxidation

Transcriptional regulation of genes involved in fatty acid metabolism is considered the major long-term regulatory mechanism controlling lipid homeostasis. By means of this mechanism, transcription factors, nutrients, hormones and epigenetics control not only fatty acid metabolism, but also many metabolic pathways and cellular functions at the molecular level. The regulation of the expression of many genes at the level of their transcription has already been analyzed. This review focuses on the transcriptional control of two genes involved in fatty acid biosynthesis and oxidation: the citrate carrier (CIC) and the carnitine/ acylcarnitine/carrier (CAC), which are members of the mitochondrial carrier gene family, SLC25. The contribution of tissue-specific and less tissue-specific transcription factors in activating or repressing CIC and CAC gene expression is discussed. The interaction with drugs of some transcription factors, such as PPAR and FOXA1, and how this interaction can be an attractive therapeutic approach, has also been evaluated. Moreover, the mechanism by which the expression of the CIC and CAC genes is modulated by coordinated responses to hormonal and nutritional changes and to epigenetics is highlighte

Presence of orexin A and orexin 1 receptor in the buffalo prostate

The orexins A and B are two peptides discovered initially in the rat lateral hypothalamus involved in the regulation of some body functions such as food intake, sleep/wake cycle, arterial pressure and heart rate. They interact with two receptors defined "orexin receptors 1 and 2", the first of which shows high selectivity for orexin A and the second binds both the peptides. In this preliminary study the presence of orexin A and orexin 1 receptor in the prostate of the buffalo Bubalus bubalis has been described utilizing the immunohistochemical avidin-biotin technique. The orexin A- and orexin 1 receptor- positive prostatic cells are very numerous and belong to the normal exocrine cytotype which makes up the glandular parenchyma. The role played by orexin A in the genital tract is poorly known. The peptide is retained to stimulate testosterone secretion and to inhibit spermatogonia proliferation in the rat testis

Neuroendocrine cells in the urogenital tract of the buffalo

Neuroendocrine cells or paraneurons are cytotypes producing biogenic amines and/or hormonal peptides, scattered in the glandular and lining epithelia of the body. In this study the presence of chromogranin A-, serotonin- and somatostatin-immunoreactive neuroendocrine cells has been described immunohistochemically in the urethro- prostatic complex and female urethra of subjects of the buffalo Bubalus bubalis. The chromogranin A- containing neuroendocrine cells resulted the most numerous cytotype, the serotonin- containing ones the most irregular in shape for the presence of dendritic-like cytoplasmic extensions and the somatostatin- containing the rarest. The role played by the amine serotonin in the genital tract has been related to the determinism of sexual climax and to the contraction of smooth muscle. The function played by the neuroendocrine genital somatostatin is unknown. Analogically to what described for the same gastrointestinal hormone, it could inhibit both exocrine and endocrine secretions

TRANSCRIPTION OF THE MITOCHONDRIAL CITRATE CARRIER GENE: ROLE OF SREBP-1, UPREGULATION BY INSULIN AND DOWNREGULATION BY PUFA

In this study we investigated the transcriptional role of the sterol regulatory element (SRE) present in the promoter of the mitochon- drial citrate carrier (CIC). We show that wild-type (but not mutated) CIC SRE cloned in front of the luciferase promoter confers tran- scriptional activation of the gene reporter. We also demonstrate that insulin activates, and polyunsaturated fatty acids (PUFA) inhibit, the gene reporter activity driven by the CIC promoter containing wild-type (but not mutated) SRE. Finally, both insulin treatment and overexpression of SRE binding protein (SREBP-1) increase the CIC transcript and protein levels, whereas PUFA have an opposite effect. These results show that SRE/SREBP-1 play a role in the transcriptional regulation of CIC by insulin and PUFA

A key role of the mitochondrial citrate carrier (SLC25A1) in TNFα- and IFNγ-triggered inflammation

The chronic induction of inflammation underlies multiple pathological conditions, including metabolic, autoimmune disorders and cancer. The mitochondrial citrate carrier (CIC), encoded by the SLC25A1 gene, promotes the export of citrate from the mitochondria to the cytoplasm, a process that profoundly influences energy balance in the cells. We have previously shown that SLC25A1 is a target gene for lipopolysaccharide signaling and promotes the production of inflammatory mediators. We now demonstrate that SLC25A1 is induced at the transcriptional level by two key pro-inflammatory cytokines, tumor necrosis factor-α (TNFα) and interferon-γ (IFNγ), and such induction involves the activity of the nuclear factor kappa B and STAT1 transcription factors. By studying the down-stream events following SLC25A1 activation during signals that mimic inflammation, we demonstrate that CIC is required for regulating the levels of nitric oxide and of prostaglandins by TNFα or IFNγ. Importantly, we show that the citrate exported from mitochondria via CIC and its downstream metabolic intermediate, acetyl-coenzyme A, are necessary for TNFα or IFNγ to induce nitric oxide and prostaglandin production. These findings provide the first line of evidence that the citrate export pathway, via CIC, is central for cytokine-induced inflammatory signals and shed new light on the relationship between energy metabolism and inflammation

Effect of layered double hydroxide intercalated with fluoride ions on the physical, biological and release properties of a dental composite resin

OBJECTIVES: The aim of this work was the preparation of a new fluoride-releasing dental material characterized by a release of fluoride relatively constant over time without any initial toxic burst effect. This type of delivery is obtained by a matrix controlled elution and elicits the beneficial effect of a low amount of fluoride on human dental pulp stem cells (hDPSCs) towards mature phenotype. METHODS: The modified hydrotalcite intercalated with fluoride ions (LDH-F), used as filler, was prepared via ion exchange procedure and characterized by X-ray diffraction and FT-IR spectroscopy. The LDH-F inorganic particles (0.7, 5, 10, 20wt.%) were mixed with a photo-activated Bis-GMA/TEGDMA (45/55wt/wt) matrix and novel visible-light cured composites were prepared. The dynamic thermo-mechanical properties were determined by dynamic mechanical analyzer. The release of fluoride ions in physiological solution was determined using a ionometer. Total DNA content was measured by a PicoGreen dsDNA quantification kit to assess the proliferation rate of hDPSCs. Alkaline phosphatase activity (ALP) was measured in presence of fluoride resins. RESULTS: Incorporation of even small mass fractions (e.g. 0.7 and 5wt.%) of the fluoride LDH in Bis-GMA/TEGDMA dental resin significantly improved the mechanical properties of the pristine resin, in particular at 37°C. The observed reinforcement increases on increasing the filler concentration. The release of fluoride ions resulted very slow, lasting months. ALP activity gradually increased for 28 days in hDPSCs cell grown, demonstrating that low concentrations of fluoride contributed to the cell differentiation. CONCLUSIONS: The prepared composites containing different amount of hydrotalcite filler showed improved mechanical properties, slow fluoride release and promoted hDPSCs cell proliferation and cell differentiation