Charm mass effects in bulk channel correlations

The bulk viscosity of thermalized QCD matter at temperatures above a few hundred MeV could be significantly influenced by charm quarks because their contribution arises four perturbative orders before purely gluonic effects. In an attempt to clarify the challenges of a lattice study, we determine the relevant imaginary-time correlator (of massive scalar densities) up to NLO in perturbation theory, and compare with existing data. We find discrepancies much larger than in the vector channel; this may hint, apart from the importance of taking a continuum limit, to larger non-perturbative effects in the scalar channel. We also recall how a transport peak related to the scalar density spectral function encodes non-perturbative information concerning the charm quark chemical equilibration rate close to equilibrium.Comment: 24 pages. v2: clarifications added, published versio

Massive vector current correlator in thermal QCD

We present an NLO analysis of the massive vector current correlator at temperatures above a few hundred MeV. The physics of this correlator originates from a transport peak, related to heavy quark diffusion, and from the quark-antiquark threshold, related to quarkonium physics. In the bottom case both can be studied with separate effective theories, but for charm these may not be accurate, so a study within the full theory is needed. Working in imaginary time, the NLO correlator can be computed in unresummed perturbation theory; comparing with lattice data, we find good agreement. Subsequently we inspect how non-perturbative modifications of the transport peak would affect the imaginary-time correlator. The massive NLO quark-number susceptibility is also contrasted with numerical measurement.Comment: 28 pages. v2: references and clarifications added, published versio

Physician and patient adherence in hypertension trials: a point of view on an important issue to resolve.

Randomized controlled trials (RCTs) are important sources of evidence that strongly influence guidelines for patient management, including for elevated blood pressure in adults. Critical questions regarding the interpretation of hypertension trial results have recently increased, especially for concerns over methodology. In particular, investigator adherence to the protocol and patient adherence to investigational drugs are often far from optimal. These issues may be ignored or underreported because physicians' behavior during trials is often not monitored and patients' medication adherence is neither measured adequately nor reported or analyzed in the final report or in the publication. This situation may lead to misinterpretations of study results and misevaluations of the safety and efficacy profile of new drugs. In this short review, the problem of measuring, reporting, and analyzing drug adherence in RCTs is discussed and illustrated with several examples in the field of hypertension. The main conclusion is that drug adherence should always be measured in clinical trials, possibly with more than one method. In addition, prespecified analyses of adherence data should be included in the statistical plan of all trials to improve their overall quality

Is the fixed-dose combination of telmisartan and hydrochlorothiazide a good approach to treat hypertension?

Blockade of the renin-angiotensin system with selective AT1 receptor antagonists is recognized as an effective mean to lower blood pressure in hypertensive patients. Among the class of AT1 receptor antagonists, telmisartan offers the advantage of a very long half-life. This enables blood pressure control over 24 hours using once-daily administration. The combination of telmisartan with hydrochlorothiazide is a logical step because numerous previous studies have demonstrated that sodium depletion enhances the antihypertensive efficacy of drugs interfering with the activity of the renin-angiotensin system (RAS). In accordance with past experience using similar compounds blocking the RAS, several controlled studies have now demonstrated that the fixed-dose combination oftelmisartan/hydrochlorothiazide is superior in lowering blood pressure than either telmisartan or hydrochlorothiazide alone. Of clinical interest also is the observation that the excellent clinical tolerance of the angiotensin II receptor antagonist is not affected by the association of the low-dose thiazide. Thus telmisartan/hydrochlorothiazide is an effective and well-tolerated antihypertensive combination. Finally, the development of fixed-dose combinations should improve drug adherence because of the one-pill-a-day regimen

Salt, blood pressure and cardiovascular risk : what is the most adequate preventive strategy? A Swiss perspective

Among the various strategies to reduce the incidence of non-communicable diseases reduction of sodium intake in the general population has been recognized as one of the most cost-effective means because of its potential impact on the development of hypertension and cardiovascular diseases. Yet, this strategic health recommendation of the WHO and many other international organizations is far from being universally accepted. Indeed, there are still several unresolved scientific and epidemiological questions that maintain an ongoing debate. Thus what is the adequate low level of sodium intake to recommend to the general population and whether national strategies should be oriented to the overall population or only to higher risk fractions of the population such as salt-sensitive patients are still discussed. In this paper, we shall review the recent results of the literature regarding salt, blood pressure and cardiovascular risk and we present the recommendations recently proposed by a group of experts of Switzerland. The propositions of the participating medical societies are to encourage national health authorities to continue their discussion with the food industry in order to reduce the sodium intake of food products with a target of mean salt intake of 5-6 grams per day in the population. Moreover, all initiatives to increase the information on the effect of salt on health and on the salt content of food are supported

Blood Oxygenation Level-Dependent MRI to Assess Renal Oxygenation in Renal Diseases: Progresses and Challenges.

BOLD-MRI (blood oxygenation-level dependent magnetic resonance imaging) allows non-invasive measurement of renal tissue oxygenation in humans, without the need for contrast products. BOLD-MRI uses the fact that magnetic properties of hemoglobin depend of its oxygenated state:: the higher local deoxyhemoglobin, the higher the so called apparent relaxation rate R2(*) (sec(-1)), and the lower local tissue oxygen content. Several factors other than deoxyhemoglobin (such as hydration status, dietary sodium intake, and susceptibility effects) influence the BOLD signal, and need to be taken into account when interpreting results. The last 5 years have witnessed important improvements in the standardization of these factors, and the appearance of new, highly reproducible analysis techniques of BOLD-images, that are reviewed in this article. Using these new BOLD-MRI analysis techniques, it has recently been shown that persons suffering from chronic kidney diseases (CKD) have lower cortical oxygenation than normotensive controls, thus confirming the chronic hypoxia hypothesis. The acute alterations in R2(*) after the administration of furosemide are smaller in CKD, and represent an estimate of the oxygen-dependent tubular transport of sodium. BOLD-MRI-alone or in combination with other functional MRI methods- can be used to monitor the renal effects of drugs, and is increasingly used in the preclinical setting. The near future will tell whether or not BOLD-MRI represents a new tool to predict renal function decline an adverse renal outcome

Neurohormonal consequences of diuretics in different cardiovascular syndromes

Diuretics have long been used to lower blood pressure in hypertensive patients or to control body fluid and electrolyte homeostasis in diseases such as congestive heart failure, chronic renal failure or cirrhosis. The initial response to diuretics is negative sodium and fluid balance. The diuretic-induced loss of salt and water activates several hormonal systems such as vasopressin, the renin-angiotensin-aldosterone system or the sympathetic nervous system which tend to compensate for the changes in sodium and water balance. This neurohormonal response may have important clinical implications. Thus, the activation of the renin-angiotensin-aldosterone cascade appears to be partially responsible for the flat dose-blood pressure response curve of thiazides in hypertensive patients. It may also be responsible for the difference between responders and non-responders to diuretic therapy and for the development of side-effects such as hypokalaemia, metabolic alkalosis or hyponatraemia. There are several ways to prevent the undesirable consequences of the neurohormonal responses to diuretics. The first is to use low doses of these agents. It is also possible to combine them with agents that block the activity of the renin-angiotensin-aldosterone system such as ACE inhibitors or in combination with drugs that reduce aldosterone secretion such as calcium antagonists. The development of drugs able to enhance urinary sodium excretion and to reduce simultaneously the activity of the renin-angiotensin-aldosterone system may offer a new interesting alternative. This might perhaps be achieved in the future with the administration of neutral endopeptidase inhibitors which interfere with the enzymatic degradation of atrial natriuretic peptid

Single-Pill Combination with Three Antihypertensive Agents to Improve Blood Pressure Control in Hypertension: Focus on Olmesartan-Based Combinations.

Blood pressure control remains an unmet clinical need. Only about half of patients achieve their blood pressure (BP) targets and of these, the majority require combination and double or triple therapies. International guidelines recommend the association of drugs with complementary mechanisms of action and, in particular, the combination of renin-angiotensin system (RAS) inhibitors, calcium channel blockers (CCBs), and diuretics. Among the various angiotensin receptor blockers, olmesartan (OM) is available as a monotherapy and in dual and triple single-pill combinations (SPCs) with amlodipine (AML) and/or hydrochlorothiazide (HCTZ). Several phase III and IV studies, together with real-world studies, have demonstrated the additional benefits of combining OM either with AML or with HCTZ in terms of BP control and target BP achievements both in the general population and in special subgroups of hypertensive patients, such as the elderly, diabetic, chronic kidney disease or obese patients. Ambulatory BP monitoring studies assessing 24h BP have also demonstrated that dual, as well as triple, OM-based SPCs induce a more sustained and smoother BP reduction than placebo and monotherapy. Furthermore, triple OM-based SPC has been shown to improve therapeutic adherence in hypertensive patients compared to free combinations. The availability of OM combined with HCTZ, AML or both at different dosages makes it a valuable option to customize therapy based on the levels of BP and the clinical characteristics of hypertensive patients