Continued importance of diuretics and beta-adrenergic blockers in the management of hypertension

Should Beta-Blockers Still be Used as Initial Antihypertensive Agents in Uncomplicated Hypertension?

Beta-blockers have long being used as first-line therapy for hypertension as their use had resulted in a reduction in cardiovascular morbidity and mortality in controlled clinical trials. A recent meta-analysis comparing beta-blockers to all other anti-hypertensive drugs taken together has found that stroke reduction was sub-optimal. Specifically, atenolol was associated with a 26% higher risk of stroke compared with other drugs. Several reasons may explain the less favourable outcomes with beta-blocker therapy. These include some adverse metabolic abnormalities such as dyslipidaemia and new-onset diabetes, and less effective reduction of central aortic compared with brachial blood pressure. Newer beta-blockers such as carvedilol or nebivolol are better tolerated. These beta-blockers have a vasodilating effect, which may beneficially affect systolic blood pressure in the aorta. Their long-term cardiovascular outcome in hypertension is still not known. Further studies would be required to show that stroke is adequately reduced by these newer beta-blockers. In conclusion, beta-blockers should not be the first drugs of choice in the management of uncomplicated hypertension. They may be used in addition to other antihypertensive agents to achieve blood pressure goals. However, in patients with angina pectoris, a previous myocardial infarction, heart failure and certain dysrhythmias, beta-blockers still play an important role. Key words: Central aortic pressure, Stroke

Midkine is a potent regulator of the catecholamine biosynthesis pathway in mouse aorta

To discover regulatory pathways dependent on midkine (Mk the gene, MK the protein) signaling, we compared the transcriptional profiles of aortae obtained from Mk -/- and wild type (WT, +/+) mice; the comparison demonstrated an extraordinary high level expression of tyrosine hydroxylase (12-fold), the rate-limiting enzyme in catecholamine biosynthesis, DOPA decarboxylase (73-fold), and dopamine beta-hydroxylase (75-fold) in aortae of Mk -/- mice compared with aortae of WT (+/+) mice. Phenylethanolamine-N-methyltransferase, the enzyme catalyzing the conversion of norepinephrine into epinephrine, was not detected in either Mk -/- and WT (+/+) mouse aorta. The protein levels of tyrosine hydroxylase, DOPA decarboxylase and dopamine beta-hydroxylase confirmed the analysis of the transcriptional profiles. Surprisingly, MK failed to regulate the enzymes of the catecholamine biosynthesis pathway in 10 other tissues studied. Furthermore, the expression levels of the enzymes of catecholamine biosynthesis in aortae of Mk -/- mice were effectively the same as those in aortae of Pleiotrophin (Ptn the gene, PTN the protein) genetically deficient (Ptn -/-) mice when compared with WT (+/+) mice. The remarkable increases in levels of expression of tyrosine hydroxylase, DOPA decarboxylase and dopamine beta-hydroxylase suggest that MK together with PTN are very important regulators of the catecholamine pathway in mouse aorta and may critically regulate catecholamine biosynthesis and function in inflammatory and the other pathological conditions in which Mk or Ptn are upregulated. The data also establish that norepinephrine is effectively the only catecholamine synthesized in mouse aorta.

The Cooper Clinic Mortality Risk Index: clinical score sheet for men

BACKGROUND

Clinical measures that are used to identify risk for specific diseases may also help physicians predict overall mortality risk in their patients. This study derived and validated a clinical scoring system that can be used to predict all-cause mortality risk in men using age, resting heart rate, blood pressure, total cholesterol, HDL-cholesterol, triglycerides, diabetes, obesity, smoking status, and cardiorespiratory fitness categories.

METHODS

This was a cohort-based prospective study of 21,766 men with no prior history of coronary heart disease, stroke, or cancer. Participants were aged 20 to 69 years at the time of their clinical examination between 1979 and 1998. The cohort was subdivided into a derivation group and a validation group. All participants underwent a clinical examination including an exercise test to determine cardiorespiratory fitness. Blood pressure, total and HDL-cholesterol, triglycerides, diabetes, and adiposity status were categorized according to clinical guidelines. Within the derivation group, a point scoring system was developed to predict all-cause mortality based on a proportional hazards regression. The point scoring system was then tested within the validation group. Data were analyzed in January 2005.

RESULTS

For the clinical mortality scoring system, the most points were assigned for greater age (e.g., 10 points for 65- to 69-year-olds), followed by diabetes (4 points), current smoking (4 points), severe obesity (3 points), low fitness (2 points), high resting heart rate (2 points), hypertension (2 points), and former smoking (1 point). A graded relationship was observed between total risk factor points and mortality risk within the derivation group, and the point scoring system accurately predicted mortality risk in the validation group. The discriminatory accuracy of the point scoring system was within acceptable limits in both the derivation group and validation group.

CONCLUSIONS

A score sheet for predicting all-cause mortality risk in men, The Cooper Clinic Mortality Risk Index, was derived and validated. This score sheet may help healthcare practitioners identify high-risk patients who might benefit from lifestyle modification, pharmacologic therapy, or other interventions.

Pleiotrophin is a major regulator of the catecholamine biosynthesis pathway in mouse aorta

To better understand the phenotype of pleiotrophin (PTN the protein, Ptn the gene) genetically deficient mice (Ptn -/-), we compared the transcriptional profiles of aortae obtained from Ptn -/- and wild type (WT, Ptn +/+) mice using a 14,400 gene microarray chip (Affymetrix) and confirmed the analysis of relevant genes by real time RT-PCR. We identified a dramatic upregulation of expression of tyrosine hydroxylase (TH), DOPA decarboxylase, and dopamine beta-hydroxylase in aortae of Ptn -/- mice in comparison with WT (Ptn +/+) mice. In contrast, transcripts of phenylethanolamine-N-methyltransferase, the enzyme catalyzing the conversion of norepinephrine into epinephrine, were not detected in aortae in either mouse strain. These findings suggest that Ptn gene expression has a critical role in determining the levels of expression of the enzymes of catecholamine biosynthesis in aorta and through this mechanism, PTN may regulate levels of endogenous catecholamine synthesis and potentially the vascular tone of aorta.