Ottimizzazione di impianti di trigenerazione con accunule termico

Dottorato di Ricerca in Ricerca operativa, XXV Ciclo, a.a. 2013Università della Calabri

Dimensionamento ottimale di impianti di trigenerazione con celle a combustibile: sviluppo di un modello di programmazione non lineare mista-intera e confronto tecnico economico con impianti tradizionali in utenze residenziali

Dottorato di Ricerca in Ingegneria Meccanica, XXI Ciclo,a.a. 2008-2009Università della Calabri

Ageing and microvasculature

A decline in the function of the microvasculature occurs with ageing. An impairment of endothelial properties represents a main aspect of age-related microvascular alterations. Endothelial dysfunction manifests itself through a reduced angiogenic capacity, an aberrant expression of adhesion molecules and an impaired vasodilatory function. Increased expression of adhesion molecules amplifies the interaction with circulating factors and inflammatory cells. The latter occurs in both conduit arteries and resistance arterioles. Age-related impaired function also associates with phenotypic alterations of microvascular cells, such as endothelial cells, smooth muscle cells and pericytes. Age-related morphological changes are in most of cases organ-specific and include microvascular wall thickening and collagen deposition that affect the basement membrane, with the consequent perivascular fibrosis. Data from experimental models indicate that decreased nitric oxide (NO) bioavailability, caused by impaired eNOS activity and NO inactivation, is one of the causes responsible for age-related microvascular endothelial dysfunction. Consequently, vasodilatory responses decline with age in coronary, skeletal, cerebral and vascular beds. Several therapeutic attempts have been suggested to improve microvascular function in age-related end-organ failure, and include the classic anti-atherosclerotic and anti-ischemic treatments, and also new innovative strategies. Change of life style, antioxidant regimens and anti-inflammatory treatments gave the most promising results. Research efforts should persist to fully elucidate the biomolecular basis of age-related microvascular dysfunction in order to better support new therapeutic strategies aimed to improve quality of life and to reduce morbidity and mortality among the elderly patients

Sortilin expression is essential for pro-nerve growth factor-induced apoptosis of rat vascular smooth muscle cells.

BACKGROUND: Sortilin, a member of the Vps10p-domain receptor family, has been demonstrated a key regulator in mediating cellular response to pro-neurotrophins. In the present study, we investigated the role of sortilin in the apoptotic pathway of vascular smooth muscle cells. METHODS AND PRINCIPAL FINDINGS: Immunohistochemistry revealed that sortilin was barely detectable in human and rat normal young vessels, while its expression was increased in human fibroatheromatous plaques. Sortilin immunodetection was also marked in the neointima of the rat aorta fifteen days after ballooning.In vitro, rat aortic intimal cells expressed higher sortilin levels than normal media SMCs; sortilin was distributed in the cytoplasm and in correspondence of the cell membrane. After 48 h, pro-nerve growth factor (proNGF) induced the strong dose-dependent increase of intimal cell apoptosis and the accumulation of sortilin protein. ProNGF was a more potent apoptotic inducer than equimolar or even higher concentration of NGF, whereas brain derived neutrotrophic factor was ineffective. Targeted interfering RNA-mediated sortilin reduction counteracted proNGF-induced apoptosis without affecting p75(NTR) expression. ProNGF-induced apoptosis was associated to NF-κB down-regulation and bax increase. Inhibition of NF-κB activity increased intimal cell apoptosis that did not further increase with the addition of proNGF. CONCLUSIONS: Our results indicate that sortilin expression characterizes human atheromatous lesions and rat aortic post-injury neointima, and suggest that sortilin represents an important regulator of proNGF-induced SMC apoptosis and arterial remodeling

GIFT-1, a phase IIa clinical trial to test the safety and efficacy of IFNγ administration in FRDA patients

Friedreich's ataxia is an autosomal recessive progressive degenerative disorder caused by deficiency of the protein frataxin. The most common genetic cause is a homozygotic expansion of GAA triplets within intron 1 of the frataxin gene leading to impaired transcription. Preclinical in vivo and in vitro studies have shown that interferon gamma (IFNγ) is able to up-regulate the expression of frataxin gene in multiple cell types. We designed a phase IIa clinical trial, the first in Italy, aimed at assessing both safety and tolerability of IFNγ in Friedreich's patients and ability to increase frataxin levels in peripheral blood mononuclear cells. Nine patients (6 female and 3 males aged 21-38 years) with genetically confirmed disease were given 3 subcutaneous escalating doses (100, 150 and 200 μg) of IFNγ (human recombinant interferon 1 b gamma, trade name IMUKIN®), over 4 weeks. The primary end-point was the assessment of the safety and tolerability of IFNγ by means of standard clinical and hematological criteria. The secondary end-point was the detection of changes of frataxin levels in peripheral blood mononuclear cells after each single escalating dose of the drug. IFNγ was generally well tolerated, the main adverse event was hyperthermia/fever. Although, increases in frataxin levels could be detected in a minority of patients, these changes were not significant. A large phase III multicenter, randomized clinical trial with IFNγ in Friedreich's ataxia patients is currently ongoing. This study is expected to conclusively address the clinical efficacy of IFNγ therapy in patients with Friedreich's ataxia

ProNGF is a potent apoptotic inducer of IT cells.

<p>IT cells (A) express TrkB and TrkC but not TrkA transcripts, while all Trk receptors are present in mSMCs. ProNGF (B and C) is a potent apoptotic inducer of IT cells and induces a dose-dependent increase of cultured rat aortic IT cell apoptosis as measured by TUNEL in serum-free medium after 24 and 48 hours; flow cytometry (D) of rat aortic intimal cells in sub-G1 (DNA content<2N) calculated as percentages of total events (10,000 cells). Agarose gel under UV light (E) after staining with ethidium bromide showing the ladder production after blunt end linker ligation confirms the dose-dependent and higher proNGF apoptotic DNA fragmentation compared to control IT cells. Representative immunofluorescence (F) of IT cells after 24 h of proNGF (10 ng/mL) treatment shows intracellular distribution of sortilin somehow more evident in the cell membrane compartment, whereas p75^NTR localization is almost unchanged<b>.</b> Blot analysis (G and H) shows that proNGF (10 ng/mL) induces the increase of sortilin protein content only after 48 h. EMSA analysis (I) in IT cells after 24 h and 48 h of treatment with proNGF shows a significant reduction of NF-κB activity (<i>upper arrow</i>, p65/50 heterodimer; <i>lower arrow</i>, p50/50 homodimer). Data are reported as mean ± SEM of three independent experiments. *<i>p</i><0.05. Scale bar = 25 µm.</p

Sortilin expression and apoptosis in normal and post-injury rat aortas.

<p>Anti-sortilin and anti-p75^NTR immunostainings (A) do not reveal detectable positivity in normal tunica media. Intimal thickening appears markedly sortilin, p75^NTR and proNGF positive fifteen days after ballooning, but not after forty-five days; α-SMA immunodetection goes in the opposite direction. TUNEL⁺ cells are evident in the neointima 15 days after ballooning (arrow heads)<b>.</b> Bar graphs (B) showing sortilin⁺, p75^NTR+ and TUNEL⁺ apoptotic intimal cell percentages; *<i>p</i><0.05. Scale bar = 50 µm.</p

Sortilin expression in rat aortic smooth muscle cell populations.

<p>Representative blot analysis of (A) sortilin protein expression and transcript levels (B) in normal rat aortic medial tissue and 15 days after ballooning. Sortilin and p75^NTR (C) transcripts accumulate in intimal cells obtained 15 days after injury (IT cells). The latter and normal media SMCs (mSMCs) were harvested after 3 and 6 days in sparse and confluent cultures, respectively. Representative blots and densitometric analysis (D and E) after normalization to CMR1 expression; data are mean ± SEM of three experiments. Sortilin and p75^NTR immunofluorescence (F) documents a higher intracellular sortilin and p75^NTR level in IT cells compared to mSMCs; right panel: merged images showing the prevalent co-localization of sortilin with p75^NTR; *<i>p</i><0.05. Scale bar = 25 µm.</p

Sortilin immunostaining of grossly normal human young and old and atherosclerotic aorta and carotid vessels.

<p>Normal young vessels (A) do not display appreciable sortilin immunodetection; the latter is observed in old vessel intimal thickening and fatty streak and, more markedly, in fibroatheromatous plaque. Representative images (B) of serial sections of human fibroatheromatous plaque stained with Haematoxylin-Eosin (H-E), α-smooth muscle actin (α-SMA), CD68, sortilin, p75^NTR and proNGF. Diaminobenzidine as chromogen, Haematoxylin counterstaining. Scale bar = 50 µm.</p