533 research outputs found
La decorazione dell’intradosso dell’arco trionfale della basilica di S. Lorenzo f.l.m.
No full textL'articolo si propone di individuare le radici della tipologia di decorazione impiegata nell'intradosso musivo dell'abside della basilica pelagiana di S. Lorenzo, indagando il repertorio del mosaico parietale di derivazione antica nella sua ultima fioritura (VI-VII sec. d.C.)
Phosphodiesterase 5 inhibition to treat essential hypertension: is this the beginning of the story?
No full textNo abstract availabl
Effects of Antihypertensive Treatment on Endothelial Function
No full textEssential hypertension is characterized by endothelial dysfunction due to reduced availability of nitric oxide (NO) secondary to increased generation of oxygen-free radicals. Some antihypertensive drugs may improve or restore endothelial function independently of their blood pressure lowering effect. The newer generation of β-blockers, such as nebivolol and carvedilol, which provide antioxidant activity, can improve endothelial function in patients with hypertension. Dihydropyridine and non-dihydropyridine calcium antagonists reverse impaired endothelium-dependent vasodilatation in different vascular districts, through a mechanism related to an antioxidant effect. However, conflicting results are found in the brachial artery. Angiotensin-converting enzyme (ACE) inhibitors improve endothelial function in subcutaneous, epicardial, brachial, and renal circulation, but they are ineffective in potentiating the impaired response to acetylcholine in the forearm of hypertensive patients. Angiotensin II receptor antagonists can restore endothelium-dependent vasodilatation to acetylcholine in subcutaneous microcirculation but not in that of the forearm muscle. They also improve basal NO release and decrease the vasoconstrictor effect of endogenous endothelin-1. Large-scale clinical trials are required to definitively demonstrate that treatment of endothelial dysfunction can improve the prognosis of patients with essential hypertension
The correct administration of antihypertensive drugs according to the principles of clinical pharmacology.
No full textControl of cardiovascular (CV) risk factors, particularly hypertension, is still unsatisfactory, resulting in excess CV morbidity and mortality worldwide. CV risk is linearly associated with an increase in blood pressure (BP) values, and clinical studies have clearly demonstrated that BP lowering represents the most effective means of preventing CV events. However, while BP reduction is a fairly easy target, BP normalization is much more difficult to achieve, and adequate BP control (<140/90 mmHg) is attained only in a small percentage of the hypertensive population. One of the main reasons for the lack of efficacy of antihypertensive pharmacological treatment is that very often drugs are not administered at the correct dosage. In this review, we discuss the importance of using clinical pharmacology to guide treatment of hypertension. Controlled clinical trials, including HOPE, EUROPA, and CONSENSUS, are used to guide prescribing decisions. Unfortunately, the results obtained in pivotal studies such as these have been obtained using drug dosages much higher than those usually used in clinical practice. The prescription of a drug for the treatment of hypertension should take into consideration the potency of the drug, i.e. the degree of BP reduction required, and the duration of action of the drug, i.e. the need to cover the dosing interval (possibly 24 hours) in a homogeneous way. This is especially the case for angiotensin-converting enzyme (ACE) inhibitors, compounds characterized by a flat dose-response curve. The significance of this flat dose-response curve is that a low dose of an ACE inhibitor has the same potency as a high dose but a shorter duration of action. If a low dosage is administered to a hypertensive patient it causes BP fluctuations, which have been associated with negative CV outcomes. In contrast, other drug classes, including calcium channel antagonists, diuretics, and β-adrenoceptor antagonists, can be used at different dosages in order to modulate their hemodynamic effects. Thus, it is important to be aware of the clinical pharmacology of antihypertensive drugs in order to choose not only the class or the molecule best suited to the clinical characteristics of the patient, but also the correct dosages to ensure effective and homogeneous 24-hour BP reduction
Phosphodiesterase 5 inhibition in essential hypertension.
No full textPhosphodiesterase (PDE) 5 inhibitors reduce cyclic guanylate monophosphate breakdown, promoting vascular relaxation in the corpora cavernosa and penile erection during sexual stimulation. Sildenafil, vardenafil, and tadalafil were approved as effective treatments for male erectile dysfunction. Because PDE5 is present in artery and vein smooth muscle cells throughout the body, PDE5 inhibitors have mild systemic vasodilatory effects and thus the potential to impact the vascular system. The US Food and Drug Administration has approved PDE5 inhibitors for treating pulmonary hypertension. Moreover, their systemic vasodilating properties theoretically make these drugs suitable for treating hypertension. Studies indicate that PDE5 inhibition may be an option for reducing blood pressure in hypertensive patients. Additional benefits may be related to improved arterial stiffness and endothelial dysfunction, two early vascular abnormalities characterizing essential hypertension. More investigation is needed on PDE5 inhibitors as antihypertensive drugs, especially with slow-release formulations or compounds with long half-life. Studies on safety during long-term administration, interactions with antihypertensive and nonantihypertensive drugs, and effect on target organ damage are needed
Hypertension and endothelial dysfunction: therapeutic approach.
No full textA large body of evidence indicates that patients with essential hypertension are characterized by endothelial dysfunction mediated by an impaired NO availability secondary to oxidative stress production. A dysfunctioning endothelium is an early marker of the development of atherosclerotic changes and can also contribute to cardiovascular events. Vascular reactivity tests represent the most widely used methods in the clinical assessment of endothelial function. In the last two decades, many studies have evaluated the endothelium in hypertensive patients, using different techniques. Several methodologies were developed to study microcirculation (resistance arteries and arterioles) and macrocirculation (conduit arteries), both in coronary and peripheral vascular districts. This review will describe the most relevant available techniques in the research on endothelial dysfunction in essential hypertension, their advantages and limitations, focusing on available data on endothelial dysfunction and on the effect of treatment. Endothelial dysfunction in the coronary and peripheral circulation of hypertensive patients are associated with hypertensive target organ damage and it is predictive of cardiovascular events. Several non-pharmacological approaches, including physical exercise and dietary interventions, can ameliorate endothelial function in hypertensive patients. Despite blood pressure reduction per se is not effective, some antihypertensive drugs can improve endothelial dysfunction, particularly calcium channel antagonist in the microcirculation, ACE-inhibitors and AT1-receptor antagonists mostly in conduit arteries. Some beneficial effects were also exerted by nebivolol and statins. Future studies are needed to confirm whether the improvement in endothelial dysfunction is associated to better cardiovascular prognosis in hypertension
Current treatment of patients with hypertension: therapeutic implications of INSIGHT
No full textWhen planning treatment for patients with hypertension, current guidelines emphasise the importance of risk stratification, based on blood pressure, the presence of end-organ damage and other cardiovascular risk factors. Because the beneficial effect of antihypertensive therapy seems to be linked to the degree of blood pressure reduction, guidelines recommend reducing blood pressure below 140/90mm Hg, with a lower target in patients who are young or who have diabetes mellitus (with or without nephropathy) or non-diabetic nephropathy. Blood pressure reduction can be achieved with several classes of drugs, including diuretics, beta-blockers, ACE inhibitors, angiotensin II antagonists and calcium channel antagonists. Calcium channel antagonists have been shown to reduce the risk of stroke and major cardiovascular events. However, it is still controversial whether different treatment regimens based on different drug classes can offer advantages beyond similar degrees of blood pressure control in preventing cardiovascular morbidity and mortality. The International Nifedipine GITS Study: Intervention as a Goal in Hypertension Treatment (INSIGHT) was a controlled clinical trial aimed at comparing the efficacy of a long-acting calcium channel antagonist, nifedipine gastrointestinal-transport-system (GITS), versus co-amilozide, a combination of the diuretics hydrochlorothiazide (HCTZ) and amiloride, on morbidity and mortality in high-risk hypertensive patients. Nifedipine GITS and HCTZ/amiloride were equally effective at reducing blood pressure and the risk of primary outcomes (a composite of death from any cardiovascular or cerebrovascular cause, non-fatal stroke, myocardial infarction and heart failure). Results from other studies indicate that there may be greater benefits for stroke and smaller benefits for coronary artery disease with calcium channel antagonist-based regimens than with diuretic or beta-blocker-based regimens. However, there is at present insufficient evidence to recommend a specific drug choice based on patient risk profile. Thus, the choice of antihypertensive drug(s) should be according to efficacy and tolerability. In addition to the reductions in cardiovascular risk, two substudies of INSIGHT showed that nifedipine GITS was able to prevent the progression of intima media thickness in the common carotid artery and slow the progression of coronary calcification. The clinical significance of this effect in the prevention of cardiovascular events still remains to be established
CFD simulation of hydrogen storage: Adsorption dynamics and thermal management in cryogenic tanks
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