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Biomedical subjects

A Salvetti

Publications and source records attributed to A Salvetti.

At least 271 records · Page 15Linked to original sources
PubMedDate not supplied

Efficient recombinant adeno-associated virus production by a stable rep-cap HeLa cell line correlates with adenovirus-induced amplification of the integrated rep-cap genome.

BACKGROUND: A possible procedure for the production of clinical grade recombinant adeno-associated virus type 2 (rAAV) would include the use of packaging cell lines, harboring the rep-cap genes and the vector, combined with a replication defective adenoviral plasmid to provide the helper activities. Several studies have already shown that rAAV can be efficiently assembled by infecting the stable packaging cell line with adenovirus. However, the direct comparison with an adenoviral plasmid has never been reported. METHODS: To investigate this point, a clone of HeLa and 293 cells harboring one to two rep-cap copies per cell genome (HeRC32 and 293RC21, respectively) were generated. Recombinant AAV was produced by transiently transfecting the AAVCMVLacZ vector and supplying the adenoviral helper activities by either wild-type adenovirus or an adenoviral plasmid (pAdc). As a control, rAAV was similarly produced from naive Hela and 293 cells additionally transfected with a rep-cap plasmid. RESULTS: Despite satisfactory rAAV yields from Hela and 293 cells, we show that those from HeRC32 and 293RC21 cells dramatically decrease when adenovirus is replaced by the adenoviral plasmid (pAdc). The analysis performed to identify the factors hampering efficient rAAV assembly by HeRC32 cells in the presence of pAdc shows that: (1) while upon adenovirus infection the integrated rep-cap genome undergoes a dramatic amplification leading to a 100-fold increase in the rep-cap copy number, no amplification is detected upon transfection of pAdc; (2) in pAdc-transfected HeRC32 cells, the intracellular localization of the adenovirus E4orf6 and E1B-55kDa proteins is abnormal as compared to adenovirus-infected cells. CONCLUSIONS: This study documents that stable rep-cap cells lines are severely hampered for rAAV assembly when a replicative adenovirus is substituted with an adenoviral plasmid. Furthermore, our results also suggest that the lack of amplification of the rep-cap genes, eventually combined with the altered distribution of the adenoviral proteins, E4orf6 and E1B-55kDa, is related to the low rAAV yields observed under these conditions.

Adenovirus E1B Proteins↗
PubMedDate not supplied

Mediation of renin release in essential hypertension by alpha-adrenoreceptors.

We studied the role of alpha-adrenoceptors in controlling renin release by infusing increasing doses of phentolamine into six patients with essential hypertension. Furthermore, in order to evaluate the relative importance of alpha 1- and alpha 2-adrenoceptors, phentolamine infusion was repeated in the same patients after pretreatment with prazosin, a selective alpha 1-blocking agent, and oxprenolol, a nonselective beta-blocker. After placebo, phentolamine infusion did not change mean blood pressure or heart rate and increased plasma renin activity (PRA) in a dose-dependent fashion. This finding suggests that the drug acts directly on the intrarenal renin producing apparatus and seems to confirm the inhibitory role of alpha-adrenoceptors in the control of renin release. After prazosin and oxprenolol pretreatment, PRA was respectively increased and decreased but it was unmodified by phentolamine infusion. This latter finding may indicate that both alpha 1- and alpha 2-adrenoceptors are involved in renin release or that alpha-adrenoceptors cannot be clearly differentiated into alpha 1- and alpha 2-subtypes.

Adult↗
PubMedDate not supplied

Naloxone does not modify the hemodynamic and neuroendocrine effects of clonidine in normal humans.

The relationship between central opioidergic and noradrenergic central control mechanisms of blood pressure was investigated in normal men by evaluating the interference exerted by naloxone, a specific opiate antagonist, on the cardiovascular (blood pressure and heart rate) and neuroendocrine [human growth hormone (HGH) stimulation] effects of clonidine, a centrally acting alpha-adrenergic agonist, according to two different protocols. In series 1, the effects of placebo (normal saline), clonidine (0.15 mg i.v.), and naloxone (0.4 mg i.v.) were compared with that of clonidine plus naloxone (0.15 and 0.4 mg i.v., respectively), in seven normal male subjects. Clonidine decreased blood pressure and heart rate, and increased HGH levels. Naloxone administered alone (0.4 mg i.v.) did not modify blood pressure, heart rate, and HGH levels, while naloxone (0.4 mg) pretreatment left unaltered the hemodynamic and neuroendocrine effects of clonidine. In series 2, in five additional normal males, the effect of increasing doses of naloxone (0.4, 2.0, and 8.0 mg i.v.) on the pharmacodynamic activity of clonidine (0.15 mg i.v.) was further evaluated. Clonidine alone decreased blood pressure and heart rate and increased HGH levels, while naloxone pretreatment, in the whole range of doses studied, did not significantly modify the action of clonidine. These data suggest that a central opioidergic tone does not modulate the effect of central alpha-noradrenergic stimulation in normal humans.

Adolescent↗
PubMedDate not supplied

Influence of endogenous androgens on carotid wall in postmenopausal women.

OBJECTIVE: There is increasing evidence of a direct association between normal androgen levels and reduced cardiovascular morbidity and mortality in women. After menopause the influence of estrogens declines, whereas that of androgens increases. Therefore, we investigated the effects of androgens on atherosclerosis in postmenopausal women, by using carotid artery intimal-medial thickness as a marker of vascular damage. DESIGN: Blood pressure, body mass index, waist-to-hip ratio, serum dehydroepiandrosterone sulfate, androstenedione, total and free testosterone, estrone, insulin, lipid profile, and glucose were evaluated in 44 women in stable physiological menopause. All subjects underwent carotid ultrasound (Biosound 2000 II s.a. high-resolution unit). RESULTS: Spearman correlation coefficients indicated that serum androstenedione and free testosterone were negatively associated with several carotid intimal-medial thickness measures with correlation coefficients (r) ranging from 0.477 to 0.397 (p < 0.01-0.04). Moreover, age-adjusted androstenedione and free testosterone highest tertiles showed intimal-medial thickness values significantly (p < 0.03-0.05) lower than the other tertiles. There was a favorable association between hormones and the most important cardiovascular risk factors. This association, however, did not reach statistical significance. Stepwise multiple regression analysis showed that the inverse relationships between the hormones (androstenedione and free testosterone) and several intimal-medial thickness measures were maintained (F: 4.15-6.07, p < 0.05-0.02) after adjustment for major cardiovascular risk factors. CONCLUSIONS: Our data demonstrate that in postmenopausal women endogenous steroid precursors and androgens are inversely related to carotid intimal-medial thickness, an established marker of atherosclerosis. In addition, these hormones show favorable associations with cardiovascular risk factors. Therefore, our study suggests that, after menopause, normal androgen levels may benefit the carotid artery wall.

Androgens↗
PubMedDate not supplied

Hemodynamic and humoral interactions between captopril and nifedipine.

Nine patients with uncomplicated essential hypertension received, according to a randomized sequence, captopril (25 mg three times daily), nifedipine (10 mg three times daily), and both drugs for 1 week, with each treatment period separated by a 1-week interval during which a placebo was given. Captopril significantly reduced blood pressure and plasma aldosterone, increased plasma renin activity (PRA), and did not change heart rate. Nifedipine exerted a similar effect on blood pressure and PRA, but it increased heart rate and did not change aldosterone. Captopril plus nifedipine further reduced blood pressure and increased PRA, did not change heart rate, and reduced aldosterone to values similar to those after captopril alone. The hypotensive effect of captopril was highly predictable by basal PRA values, and that of nifedipine by age, while PRA increments induced by captopril were unrelated to those induced by nifedipine. These data indicate that: 1) captopril and nifedipine exert an additive effect on blood pressure and renin; 2) captopril counteracts the heart rate increase induced by nifedipine; 3) nifedipine does not influence the aldosterone inhibition induced by captopril. It is suggested that the association of the two drugs can be usefully employed in the treatment of hypertension.

Adult↗
PubMedDate not supplied

Pathogenetic factors in hypertension. Endothelial factors.

In normotensive humans, endothelium modulates vascular tone mainly by the production of nitric oxide. In human essential hypertension the basal release of nitric oxide is reduced and forearm vasodilation to the endothelium-dependent agonists acetylcholine or bradykinin is blunted. Defective basal release of nitric oxide seems to be secondary to blood pressure increase while impaired agonist-evoked endothelium-dependent vasodilation is probably a primary phenomenum. This latter endothelial dysfunction seems to be caused by the simultaneous presence of an alteration in the L-arginine-nitric oxide pathway and the production of constrictor prostanoids. Defective nitric oxide production is already detectable in normotensive offspring of hypertensive patients and young essential hypertensive. In contrast, vasoconstrictor prostanoid production seems to be associated with aging. In essential hypertensive patients, although only scanty data are available, chronic effective pharmacological treatment seems to restore impaired basal production of nitric oxide but does not improve vascular response to endothelial agonists.

Adult↗
PubMedDate not supplied

[Chronic inflammation and endothelial dysfunction: analysis of a cohort of patients with SLE and UCTD].

OBJECTIVE: Cardiovascular complications, mainly caused by an accelerated atherosclerosis, are one of the leading causes of death and disability in patients with systemic autoimmune diseases. Endothelial dysfunction is considered the earliest and reversible step of atherogenesis. Aim of the present study is to investigate endothelial function (EF) in patients with systemic lupus erythematosus (SLE), undifferentiated connective tissue diseases (UCTD) and correlate the results with clinical and laboratory variables. METHODS: EF was assessed on the peripheral microcirculation by the perfused forearm technique that can estimate both endothelium- dependent and endothelium- independent vasodilatation. The same evaluation has been repeated in two patients after the administration of 20 mg of 6-metilprednisolone. RESULTS: Twenty-three female patients with SLE or UCTD, with a follow up of at least 1 year have been studied and compared with 8 healthy controls matched for epidemiological variables and traditional risk factors for cardiovascular disease. A significant reduction both in endothelium dependent than endothelium independent vasodilatation was observed in both patients groups compared with controls. In addition, UCTD patients demonstrated a significant reduction in the nitric oxide pathway compared with controls and SLE patients. Finally, steroid administration induced an improvement of vascular reactivity. CONCLUSIONS: Despite the well documented side effects of chronic corticosteroid therapy, our data might suggest a role for antinflammatory and immunosuppressive therapy in the prevention of premature atherosclerosis in patients with systemic autoimmune diseases.

Adult↗
PubMedDate not supplied

Treatment of renovascular disease and of renovascular hypertension.

Treatment of occlusive lesions of renal arteries, defined as renovascular disease (RVD), is aimed both at preventing ischemic renal disease (IRD) and rescuing renal function through revascularization procedures, such as PTRA, endovascular stenting and surgical revascularization, as well as curing or improving hypertension in the presence of renovascular hypertension (RVH), i.e. hypertension caused by these vascular lesions. Preventive treatment of IRD is still an individual decision making process based on the type of renal lesions, degree of renal stenosis and progressive loss of renal mass as well as on immediate and late technical success of revascularization procedures together with their rate of complications. Rescue of renal function and-or prediction of the outcome of renal function after successful revascularization depends not only on the possibility of clarifying whether the decrease in renal function is a functioning-reversible phenomenon linked to renal hypoperfusion but also on the potential risk that the revascularization procedure may induce irreversible kidney damage. The rationale for treating RVH through revascularization procedures derives from the possibility of establishing a pathogenetic link between the occlusive lesions and hypertension, mainly through renal vein renin measurement and captopril renography and possibly their combination. Finally, medical treatment of hypertension is needed in patients who cannot undergo or refuse revascularization and whose blood pressure is not normalized by these procedures.

Humans↗
PubMedDate not supplied

Endothelial dysfunction in hypertension.

Endothelium can deeply influence vascular tone and structure. The main endothelium derived factor is nitric oxide, which is not only a potent vasodilator but also inhibits platelet aggregation, smooth muscle cell migration and proliferation, monocyte adhesion and adhesion molecule expression, thus protecting the vessel wall against the development of atherosclerosis and thrombosis. In human hypertension, endothelial dysfunction has been documented in peripheral and coronary macro and microcirculation and in renal circulation. Impaired endothelium-dependent vasodilation associated with essential hypertension seems to be a primary phenomenon, since it can be detected in the offspring of essential hypertensive patients, shows no clear correlation with blood pressure value, and is not normalized by the mere reduction of blood pressure. The phenomenon responsible for endothelial alteration in essential hypertensive patients seems to be the activation of an alternative pathway involving cyclooxygenase which reduces NO availability through production of oxidative stress. This alteration in the NO pathway could be the main mechanism through which a dysfunctional endothelium could be a promoter of atherosclerosis and thrombosis in essential hypertension.

Endothelium, Vascular↗