l-Arginine prevents inflammatory and pro-calcific differentiation of interstitial aortic valve cells.

BACKGROUND AND AIMS: Reduced bioavailability of nitric oxide (NO) has been implicated in the pathogenesis of calcific aortic stenosis. Herein, we investigated the effects of l-Arginine, the main precursor of NO, on the osteogenic differentiation of aortic interstitial valve cells (VICs). METHODS: We isolated a clonal population of bovine VICs that expresses osteogenic markers and induces calcification of collagen matrix after stimulation with endotoxin (LPS 500 ng/mL). VICs were treated in vitro with different combinations of LPS ± l-Arginine (50 or 100 mM) and cell extracts were collected to perform proteomic (iTRAQ) and gene expression (RT-PCR) analysis. RESULTS: l-Arginine prevents the over-expression of alkaline phosphatase (ALP, p < 0.001) and reduces matrix calcification (p < 0.05) in VICs treated with LPS. l-Arginine also reduces the over-expression of inflammatory molecules induced by LPS (TNF-alpha, IL-6 and IL-1beta, p < 0.001). The proteomic analysis allowed to identify 49 proteins with an altered expression profile after stimulation with LPS and significantly modified by l-Arginine. These include proteins involved in the redox homeostasis of the cells (i.e. Xanthine Oxidase, Catalase, Aldehyde Oxidase), remodeling of the extracellular matrix (i.e. ADAMTSL4, Basigin, COL3A1) and cellular signaling (i.e. Fibrillin-1, Legumain, S100A13). The RT-PCR analysis confirmed the modifications of Fibrillin-1, ADAMTSL4, Basigin and Xanthine Oxidase, whose expression levels increase after stimulation with LPS and are reduced by l-Arginine (p < 0.05). CONCLUSIONS: l-Arginine prevents osteogenic differentiation of VICs and reduces matrix calcification. This effect is achieved through the modulation of proteins involved in the cellular redox system, remodeling of extracellular matrix and inflammatory activation of VICs.

Warfarin, but not rivaroxaban, promotes the calcification of the aortic valve in ApoE-/- mice.

INTRODUCTION: Vitamin K antagonists, such as warfarin, are known to promote arterial calcification through blockade of gamma-carboxylation of Matrix-Gla-Protein. It is currently unknown whether other oral anticoagulants such as direct inhibitors of Factor Xa can have protective effects on the progression of aortic valve calcification. AIMS: To compare the effect of warfarin and rivaroxaban on the progression of aortic valve calcification in atherosclerotic mice. RESULTS: 42 ApoE-/- mice fed with Western-type Diet (WTD) were randomized to treatment with warfarin (n = 14), rivaroxaban (n = 14) or control (n = 14) for 8 weeks. Histological analyses were performed to quantify the calcification of aortic valve leaflets and the development of atherosclerosis. The analyses showed a significant increase in valve calcification in mice treated with warfarin as compared to WTD alone (P = .025) or rivaroxaban (P = .005), whereas no significant differences were found between rivaroxaban and WTD (P = .35). Quantification of atherosclerosis and intimal calcification was performed on the innominate artery of the mice and no differences were found between the 3 treatments as far as atherogenesis and calcium deposition is concerned. In vitro experiments performed using bovine interstitial valve cells (VIC) showed that treatment with rivaroxaban did not prevent the osteogenic conversion of the cells but reduce the over-expression of COX-2 induced by inflammatory mediators. CONCLUSION: We showed that warfarin, but not rivaroxaban, could induce calcific valve degeneration in a mouse model of atherosclerosis. Both the treatments did not significantly affect the progression of atherosclerosis. Overall, these data suggest a safer profile of rivaroxaban on the risk of cardiovascular disease progression.

RANKL Expression Is Increased in Circulating Mononuclear Cells of Patients with Calcific Aortic Stenosis.

We aimed to investigate whether the expression of the OPG/RANK/RANKL triad in peripheral blood mononuclear cells (PBMC) and circulating levels of markers of ectopic mineralization (OPG, FGF-23, PPi) are modified in patients with calcific aortic valve disease (CAVD). We found that patients affected by CAVD (n = 50) had significantly higher circulating levels of OPG as compared to control individuals (p = 0.003). No differences between the two groups were found in FGF-23 and PPi levels. RANKL expression was higher in the PBMC from CAVD patients (p = 0.018) and was directly correlated with the amount of valve calcification (p = 0.032). In vitro studies showed that treatment of valve interstitial cells (VIC) with RANKL plus phosphate was followed by increase in matrix mineralization (p = 0.001). In conclusion, RANKL expression is increased in PBMC of patients with CAVD, is directly correlated with the degree of valve calcification, and promotes pro-calcific differentiation of VIC.

Cardiovascular risk and hypertension control in Italy. Data from the 2015 World Hypertension Day.

BACKGROUND: Cardiovascular diseases (CVD) are the first cause of death and disability in western countries. Despite therapeutic advances, their prevalence is constantly increasing. Detailed assessment of modifiable CV risk factors could improve CVD prevention and management. METHODS: to assess CV risk and hypertension control in a sample of the Italian population, individuals participating to the 2015 "World Hypertension Day" were interviewed in 62sites all over Italy. Blood pressure was measured with a validated auscultatory or oscillometric device and information on demography and prevalence of CVD risk factors was collected by an anonymous questionnaire. An ad-hoc modified version of the Systematic COronary Risk Evaluation (SCORE) system was then applied. RESULTS: 8657 recruited individuals (43%women, aged 56.68±16years) were subdivided into 3 age groups (40-49y, 50-59y, 60-69y) for analysis. CV risk was low in 62.4%, 18.0% and 0%; moderate in 26.0%, 66.0% and 62.5%; high/very high in 11.6%, 16% and 37.4%, respectively. Smoking was mainly responsible for increased CV risk among those aged 40-49y (26%smokers), while hypertension was the main factor in the whole sample and in subjects over 50y (36% and 42% respectively). Overall, BP control was unsatisfactory in 36% of individuals (28%, 48% and 31% of those who declared to be normotensive, hypertensive on treatment or unaware of their BP condition, respectively). CONCLUSIONS: In this sample of the Italian population, CV risk was alarmingly high, irrespectively of age, mostly due to presence of modifiable risk factors, including hypertension, which should thus be better addressed, especially in the youngsters.

Atorvastatin Reduces Circulating Osteoprogenitor Cells and T-Cell RANKL Expression in Osteoporotic Women: Implications for the Bone-Vascular Axis.

AIM: Circulating osteoprogenitors and receptor activator of nuclear factor kappa-B ligand (RANKL) expression in immune cells have been implicated in the pathogenesis of osteoporosis and vascular calcification. The role played by statin therapy in the bone-vascular axis is unknown. METHODS: Twenty naïve postmenopausal osteoporotic hypercholesterolemic women were treated with Atorvastatin 40 mg/day for 3 months. Gene expression analysis was performed to assess modification in osteoprotegerin (OPG)/RANK/RANKL expression in isolated T cells and monocytes. A flow cytometry analysis was used to study changes in the levels of circulating osteoprogenitor cells. RESULTS: After 3 months of treatment, Atorvastatin significantly reduced total cholesterol and LDL-C, without affecting HDL-C and triglycerides. Among circulating bone and phosphocalcium homeostasis markers, we found a significant increase in OPG levels (P < 0.01) and a modest reduction in osteocalcin (OCN) (P < 0.05). We also observed a significant reduction in RANKL expression in T cells (P < 0.05). No differences were found in the expression of RANK in T cells and RANKL and RANK in monocytes. OPG expression was low in both immune cell types and was not affected by the treatment. As for circulating osteoprogenitors, we found a significant reduction of CD34(+) BAP(+) (P < 0.05) and CD34(+) OCN(+) BAP(+) (P < 0.05) cells. In vitro studies showed that Atorvastatin reduced RANKL expression in activated human T-lymphoblastoid cells (Jurkat cell line). CONCLUSIONS: Three-month Atorvastatin treatment leads to a reduction in circulating osteoprogenitor cells and RANKL expression in T cells, as well as increase in OPG serum levels. These data suggest that statins could have protective effects in the bone-vascular axis.

Extracellular pyrophosphate is reduced in aortic interstitial valve cells acquiring a calcifying profile: implications for aortic valve calcification.

OBJECTIVES: Pyrophosphate (PPi) is a potent inhibitor of ectopic mineralization but its role during aortic valve calcification is not known. METHODS: Anti-calcific effect of PPi was investigated by using an in vitro model of serum-driven calcification of collagen sponges and decellularized porcine aortic valve leaflets. Bovine interstitial valve cells (VIC), seeded either within the collagen matrices or in transwell chambers, were used to test cellular ability to inhibit serum-induced calcification. PPi metabolism was investigated in clonal VIC harboring different calcifying potential. RESULTS: In a cell-free system, high serum levels induced a dose-dependent calcification of type I collagen matrices which was prevented by PPi and ATP supplementation. Blockade of serum-driven calcification by PPi and ATP was also observed when using decellularized porcine aortic valve leaflets. A similar anti-calcific effect was also seen for bovine VIC, either statically seeded into the collagen matrices or co-cultured by using a transwell system. However, when we performed co-culture experiments by using clonal VIC harboring different calcifying potential, we observed that the subset of cells acquiring a pro-calcific profile lost the ability to protect the collagen from serum-driven calcification. Pro-calcific differentiation of the clonal VIC was accompanied by increase in ALP along with significant reduction in NPP activity and ATP/PPi extracellular accumulation. These changes were not observed in the clonal subtype with lower propensity towards calcification. CONCLUSIONS: We showed that PPi and ATP are potent inhibitors of serum-driven calcification of collagen matrix and that their extracellular accumulation is reduced in calcifying VIC.

Atherosclerosis progression in psoriatic arthritis patients despite the treatment with tumor necrosis factor-alpha blockers: a two-year prospective observational study.

OBJECTIVE: To evaluate the progression of subclinical atherosclerosis in Psoriatic Arthritis (PsA) patients treated with anti-tumor necrosis factor (TNF)-α agents. METHODS: Thirty-two PsA patients classified according to the CASPAR criteria and attending the Rheumatology Unit of the University of Padua Medical Center were enrolled in a two-year prospective, observational study. In accordance with the ASAS/EULAR recommendations on the management of these patients, those studied were prescribed biological agents [etanercept (n=21), adalimumab (n=6), infliximab (n=5)]. Plasma lipids, inflammatory biomarkers, including C-reactive protein (CRP), interleukin-6 (IL-6), vessel endothelium growth factor (VEGF), osteoprotegerin (OPG), and TNF-α, as well as Disease Activity Score 28 calculated with CRP (DAS 28-CRP) were evaluated at baseline and after two years of treatment. Bilateral carotid B-mode ultrasound measurements [the mean-intima media thickness (mean-IMT), the mean maximum-IMT (M-Max)] of each carotid artery segment (common, bulb, and internal carotid artery) and the post-occlusion flow-mediated dilation (FMD) of the brachial artery were also assessed at baseline and after two years. RESULTS: Despite an improvement in the DAS 28-CRP score (P<0.0005) and lower low-density lipoprotein cholesterol (P<0.013) and triglyceride (P<0.036) values, there was a significant progression in both the mean-IMT (P<0.0005) and M-Max (P<0.0005). Moreover, no recovery in FMD (P=ns) was observed after two years of anti TNF-α treatment. Serum TNF-α levels were increased (P=0.003) and OPG values were decreased (P=0.011) at the end of follow- up with respect to baseline values. CONCLUSIONS: Despite improvement in clinical status, arterial remodelling was observed in the PsA patients who were treated with anti TNF-α agents for two years.

Osteoprotegerin in cardiovascular disease: ally or enemy?

The OPG/RANK/RANKL axis is now recognized as a master regulator of bone remodeling, controlling osteoclast's maturation and extracellular matrix calcification. Nevertheless, a number of clinical and basic science studies conducted in the last few years demonstrated that the triad could be also involved in several physiological and pathological processes outside the bone tissue. In particular, evidences have been collected showing an active participation of OPG and RANKL in vascular pathology, including atherogenesis and arterial calcification. A series of epidemiological studies also showed that increased circulating levels of OPG are associated with significant, independent predictive value for future cardiovascular mortality/morbidity. However, the human studies did not unravel whether OPG should be considered as a promoter, a protective mechanism or is instead neutral with regard of vascular disease progression. Main objective of the present review is to summarize findings from both in vivo and in vitro investigations on the role played by OPG in vascular disease progression and to delineate a plausible scenario on the actual involvement of the OPG/RANK/RANKL triad and TRAIL in cardiovascular pathology.

Aortic valve calcification in chronic kidney disease.

Several clinical studies reported an increased prevalence and accelerated progression of aortic valve calcification among patients with end-stage renal disease when compared with subjects with normal kidney function. Recently, mechanisms of calcific valve degeneration have been further elucidated and many of the pathways involved could be amplified in patients with decreased renal function. In particular, calcium-phosphate balance, MGP metabolism, OPG/RANK/RANKL triad, fetuin-A mineral complexes and FGF-23/Klotho axis have been shown to be impaired among patients with advanced chronic kidney disease and could play a role during vascular/valve calcification. The scope of the present review is to summarize the clinical data and the pathophysiological mechanisms potentially involved in the link between renal function decline and the progression of aortic valve disease.

An Unusual Case of Fibromuscular Dysplasia with Bilateral Renal Macroaneurysms: Three-year Outcome After Endovascular Treatment.

Fibromuscular dysplasia (FMD) is an idiopathic, segmental, non-inflammatory and non-atherosclerotic disease that affects arterial walls, leading to stenosis of small and medium-sized arteries. FMD mostly involves renal and intracranial arteries and only in few patients is associated with macroaneurysms (RAAs). We present the case of a 45-years old woman with recent history of grade 2 hypertension that suffered of subarachnoid haemorrhage due to rupture of a basilar artery aneurysm. The cerebral aneurysm was immediately treated by coil embolization and an abdominal angio-CT scan was performed to investigate the presence of renovascular hypertension. The exam showed the presence of FMD of the renal arteries associated with presence of bilateral RAAs. Due to the high risk of rupture, the bigger aneurysm (2,5 cm diameter) present on the left artery was immediately treated by coil embolization. The fusiform aneurysm, present on the right renal artery, was instead treated one year later by using two flow diverter stents. After three years, an angiographic study showed that both cerebral and renal aneurysms were excluded from the blood flow without evidence of arterial restenosis.

Lipoprotein remnants and dense LDL are associated with features of unstable carotid plaque: a flag for non-HDL-C.

OBJECTIVE: We investigated the association between cholesterol across the LDL density range and in the VLDL and IDL particles with the prevalence of inflammatory cells in plaques of patients with severe carotid artery stenosis. METHODS: Forty-five patients undergoing carotid endarterectomy were studied. Plaque specimens were analyzed for cellular composition by immunocytochemistry using monoclonal antibodies. Lipoprotein subclasses were separated by gradient ultracentrifugation. RESULTS: We found no correlations between LDL-C, HDL-C and plasma triglyceride levels with plaque cellular composition. On the other hand, macrophage content was significantly related to cholesterol in the dense LDL subclasses (r = 0.30, p < 0.01) and in the triglyceride-rich lipoprotein remnants, namely dense VLDL and IDL particles (r = 0.46, p < 0.01). HDL subclasses were not correlated with plaque cellular composition. In a mirror manner, smooth muscle cells were inversely associated with cholesterol levels of the dense LDL subclasses (r = -0.32, p < 0.01 fraction 10; r = -0.26, p < 0.05 fraction 11) while only a non-significant trend was observed with the cholesterol in the VLDL-IDL fractions. These results provide the pathophysiological background to account for the relevance of non-HDL-C as the only lipid parameter, aside LDL density, significantly associated (ß = 0.351, p = 0.021) with carotid plaque macrophage content. CONCLUSIONS: We provide evidence that lipoprotein subclasses, specifically cholesterol in the dense LDL fractions and in the triglyceride-rich lipoprotein remnants, significantly affect carotid plaque cellular composition, in particular macrophages content.

Hypertension and vascular calcification: a vicious cycle?

It is now well established that hypertension is accompanied by remodeling of the arterial wall with significant modifications in extracellular matrix composition and in vascular cell phenotype. Some of these changes, particularly elastin fragments generation, increased proteases activity and activation of transforming growth factor-ß signaling together with deposition of collagen and proteoglycans might generate a permissive soil for vascular calcification. On the other hand, calcium deposits within large arterial conduits can reduce vessel's elasticity and contribute to the generation of blood pressure pattern associated with vascular stiffness, namely isolated systolic hypertension. Hence, a hypothetical vicious cycle exists between hypertensive arterial damage and vascular calcification. Herein, we revised clinical and basic science findings supporting this possibility.

The effects of basic fibroblast growth factor in an animal model of acute mechanically induced right ventricular hypertrophy.

OBJECTIVE: To evaluate the effect of a continuous infusion of basic fibroblast growth factor on the adaptive potential of the right ventricular myocardium after 30 days of mechanically induced overload in rats. Materials and methods We banded the pulmonary trunk, so as to increase the systolic workload of the right ventricle, in six Lewis/HanHsd rats at the age of 11 weeks, using six adult rats as controls. The six adult rats were also banded and received an additional continuous infusion of basic fibroblastic growth factor, using six rats with a continuous infusion of basic fibroblastic growth factor only as controls. We analysed the functional adaptation and structural changes of the right ventricular myocardium, blood vessels, and interstitial tissue 30 days after the increased afterload. RESULTS: The pulmonary artery banding induced an increase in the right ventricular free wall thickness of banded rats when compared with controls, which was mainly justified by an increase in cardiomyocyte area and in the percentage of extracellular fibrosis. The infusion of basic fibroblastic growth factor promotes a more extensive capillary network in banded rats (p < 0.001), which modulates the compensatory response of the right ventricle, promoting the hypertrophy of contractile elements and limiting the areas in which fibrosis develops (p < 0.001). CONCLUSIONS: The subcutaneous infusion with osmotic pumps was a valid and reproducible method of delivering basic fibroblast growth factor to heart tissue. This infusion contributed to better preserve the right ventricular capillary network, hampering the development of interstitial fibrosis.

Proteomic analysis of clonal interstitial aortic valve cells acquiring a pro-calcific profile.

Calcific degeneration represents the most frequent aortic valve disease observed in industrialized countries. Our aim is to study modifications in the cytosolic and membrane protein profile of aortic interstitial valve cells (VIC) acquiring a pro-calcific phenotype. We studied a clonal population of bovine VIC that expresses bone-related proteins (such as alkaline phosphatase [ALP]) and calcifies a collagen matrix in response to endotoxin (LPS) treatment. A proteomic analysis was performed on proteins extracted from cells treated for 12 days with LPS (100 ng/mL) versus control. We identified 34 unique cytosolic and 10 unique membrane-associated proteins showing significant changes after treatment. These proteins are involved in several cellular functions, such as chaperone-mediated protein folding, protein metabolism and transport, cell redox/nitric oxide homeostasis, and cytoskeletal organization. Reduced expression of proteins involved in NOS bioactivity (such as DDAH-1 and -2) suggested a role for the l-arginine/ADMA ratio in controlling VIC phenotypic profile. In accordance with this hypothesis, we observed that exposure of clonal cells to l-arginine prevented LPS-induced ALP expression and collagen calcification. In conclusion, we identified several proteins involved in structural, metabolic, and signaling functions that are significantly altered in aortic VIC acquiring a pro-calcific profile, thus giving new insights into the pathogenesis of aortic valve degeneration.

Atorvastatin reduces macrophage accumulation in atherosclerotic plaques: a comparison of a nonstatin-based regimen in patients undergoing carotid endarterectomy.

BACKGROUND AND PURPOSE: The object of our study was to compare the effect of high-dose vs low-dose atorvastatin vs nonstatin-based treatment (cholestyramine plus sitosterol) on cell composition of carotid plaque. METHODS: We recruited 60 hypercholesterolemic patients (total cholesterol, 5.83-7.64 mmol/L) eligible for carotid endarterectomy. Three months before surgery, patients were randomized into 3 groups (n=20) receiving atorvastatin 10 mg/day (AT-10) or atorvastatin 80 mg/day (AT-80) or cholestyramine 8 g/day plus sitosterol 2.5 g/day. Analysis of cell composition was performed on endarterectomy specimens. RESULTS: The 3 treatments resulted in a significant reduction of total cholesterol and low-density lipoprotein cholesterol (LDL-C), although the decrease in total cholesterol and LDL-C was of smaller magnitude in the cholestyramine plus sitosterol group. The 3 regimens did not influence the levels of inflammatory markers (including high-sensitivity C-reactive protein). Macrophage content was significantly lower in the AT-10 group plaques compared to the cholestyramine plus sitosterol group. It was further reduced in the AT-80 group plaques. These differences were no longer significant after adjustment for changes in LDL-C. No difference in lymphocyte number was observed among treatments, whereas the content of smooth muscle cells was higher in the AT- 80 group. An inverse association was observed between LDL-C changes in the 3 groups and macrophage content in the plaques. CONCLUSIONS: Short-term treatment with high-dose statin is superior to a nonstatin lipid-lowering regimen in reducing the macrophage cell content within atherosclerotic lesions, but this effect was determined by the degree of LDL-C-lowering.

Clones of interstitial cells from bovine aortic valve exhibit different calcifying potential when exposed to endotoxin and phosphate.

OBJECTIVE: Our purpose was to study in vitro whether phenotypically-distinct interstitial cell clones from bovine aortic valve (BVIC) possess different calcifying potential in response to endotoxin (lipopolysaccharide [LPS]) and phosphate (Pi). METHODS AND RESULTS: Among various clones of BVIC obtained by limited dilution technique we selected 4 clones displaying different growth patterns and immunophenotypes. Uncloned and cloned cells were treated with combinations of LPS (100 ng/mL) and Pi (2.4 mmol/L). Uncloned BVIC showed increased alkaline phosphatase activity (ALP) after treatment with LPS, which resulted in calcification after addition of Pi. Among BVIC clones, only Clone 1 (fibroblast-like phenotype) showed a relevant increase in ALP after LPS treatment in parallel with prevention of smooth muscle (SM) alpha-actin accumulation. No effect was observed in clonal cells harboring a more stable SM cell-like profile (Clone 4). None of the isolated clones calcified but mineralization was induced in the presence of LPS plus Pi when Clone 1 was cocultured with Clone 4 or after seeding on type I collagen sponges. CONCLUSIONS: Endotoxin and phosphate can act as valve calcification promoters by targeting specific fibroblast-like interstitial valve cells that possess a unique procalcific potential.

Critical role of macrophages in glucocorticoid driven vascular calcification in a mouse-model of atherosclerosis.

OBJECTIVE: Macrophage-derived products are known to play a crucial role during atherogenesis and vascular calcification. Glucocorticoids (GC) are important modulators of immune cell functions, but their specific effects on macrophages behavior during plaque formation are not defined. The present study was therefore designed to investigate the effects of macrophage-specific deletion of the glucocorticoid receptor (GR(LysMCre)) on atherogenesis and vascular calcification in a hyperlipidemic mouse-model. METHODS AND RESULTS: Bone marrow was isolated from GR(LysMCre) mice and wild-type controls (GR(flox)) and subsequently transplanted into lethally irradiated LDL-receptor-deficient mice. Animals were fed a Western-type diet for 15 or 24 weeks, and atherosclerotic lesions within the aortic sinus were evaluated. At both time points, no significant difference in serum lipid and corticosterone concentrations, atherosclerotic lesion size and macrophage-content within the lesions could be observed. However, GR(LysMCre) mice showed less calcification as well as a significant reduction of RANKL, BMP2, and Msx2 expression within the vasculature. In vitro studies using conditioned media from macrophages which had been stimulated with dexamethasone demonstrated a dose-dependent increase in calcium deposition by vascular smooth muscle cells. CONCLUSIONS: This study demonstrates that macrophage-specific glucocorticoid receptor inactivation reduces vascular calcification without affecting atherosclerotic lesion size in LDL receptor-deficient mice.

Aryl hydrocarbon receptor interacting protein (AIP) gene mutation analysis in children and adolescents with sporadic pituitary adenomas.

OBJECTIVE: Pituitary adenomas occur rarely in childhood and adolescence. Pituitary adenoma predisposition (PAP) has been recently associated with germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene. The aim of the study was to examine the proportion of germline AIP mutations in apparently sporadic paediatric pituitary adenomas. DESIGN: Genomic DNA was analysed for mutations in the AIP gene, by PCR amplification and direct sequencing. PATIENTS: A population-based cohort consisting of 36 apparently sporadic paediatric pituitary adenoma patients, referred to two medical centres in Italy, was included in the study. Patients were either less than 18 years at diagnosis, or showed clinical evidence of adenoma development before the age of 18 years. RESULTS: A heterozygous in-frame deletion Y248del (c.742_744delTAC) was identified in one GH-secreting adenoma patient. Loss of heterozygosity (LOH) analysis of tumour DNA revealed the loss of the wild-type allele. First degree relatives carrying the mutation were clinically unaffected. CONCLUSIONS: While mutations were absent in non-GH-secreting adenoma patients, germline AIP mutations can be found in children and adolescents with GH-secreting tumours, even in the absence of family history. The present study reports the AIP mutation analysis results on patients of a single ethnic origin. Clearly, further studies are needed to improve our knowledge on the role of AIP in paediatric pituitary adenomas.

The good and the bad in the link between insulin resistance and vascular calcification.

Medial arterial calcification is a common finding in subjects with diabetes mellitus. In vitro, glucose or insulin supplementations promote a phenotypic shift of smooth muscle cells into osteogenic cells, but the mechanisms driving this conversion are poorly understood. The binomial hyperglycaemia/hyperinsulinemia is typical of insulin resistance states, in which the metabolic and vasomotor ("good") actions of insulin are selectively impaired, whereas its mitogenic ("bad") signals are potently enhanced. Under these conditions, insulin can exert pro-atherosclerotic effects and promote vascular calcification. In this setting, the metabolic and mitogenic pathways may be not entirely antagonist, because they interact to traduce the normal insulin signal into inhibition of calcification. Emerging data suggest that the two pathways may converge on the regulation of phosphate transport and extracellular inorganic phosphate (Pi) concentrations. Two antagonist enzymes governing Pi metabolism are alkaline phosphatase (ALP) and the ectonucleotide pyrophosphatase/phosphodiesterase-1 (also known as PC-1): while ALP is up-regulated in calcified diabetic arteries, PC-1 is also implicated in the genesis of insulin resistance. Therefore, we suggest that the functional interactions between ALP and PC-1 may link insulin resistance to vascular calcification.