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Biomedical subjects

J N Cohn

Publications and source records attributed to J N Cohn.

At least 37 records · Page 2Linked to original sources
PubMed2001

Small and large artery elasticity indices in peripheral arterial occlusive disease (PAOD).

In peripheral arterial occlusive disease (PAOD), arterial compliance of the central arteries has been reported to be reduced. It is, however, not clear whether, in PAOD, decreased arterial compliance is also accompanied by similar changes in the peripheral arteries. Therefore the aim of the study was to determine the large (C1) and small (C2) artery elasticity indices in PAOD and their relations to its well-accepted characteristics (ankle-brachial index, ABI; pulse pressure, PP; absolute claudication distance, ACD). A total of 43 patients with PAOD (mean age 68 +/- 9 years; ABI of the limiting leg 0.65 +/- 0.14; SBP (systolic blood pressure) 149 +/- 20 mmHg, and ACD 488 +/- 187 m) were enrolled as well as 16 control subjects of comparable age (69 +/- 4 years) and blood pressure (SBP 147 +/- 27 mmHg). All subjects underwent non-invasive pulse wave analysis in order to determine arterial compliance of the aorta and major side branches (C1) and of the distal circulation (C2), using a modified Windkessel model. In PAOD, both C1 (1.41 +/- 0.56 ml/mmHg) and C2 (0.023 +/- 0.012 ml/mmHg) were comparable to values in an age and blood pressure-matched control group (C1, 1.25 +/- 0.66 ml/mmHg; C2, 0.027 +/- 0.008 ml/mmHg). C1 was significantly correlated with ACD (r = 0.36, p = 0.02), PP (r = -0.33, p < 0.02) and only borderline with ABI (r = 0.28, p = 0.07). C2 was correlated with PP (r = -0.38, p < 0.01), ABI (r = 0.36, p < 0.02) but not with ACD. Large (C1) and small (C2) artery elasticity indices in PAOD were decreased but comparable to values in an elderly group with isolated systolic hypertension. Moreover, C1 and C2 correlated with markers (ABI and PP) of severity of vascular disease.

Aged↗
PubMed2000

New guidelines for potassium replacement in clinical practice: a contemporary review by the National Council on Potassium in Clinical Practice.

This article is the result of a meeting of the National Council on Potassium in Clinical Practice. The Council, a multidisciplinary group comprising specialists in cardiology, hypertension, epidemiology, pharmacy, and compliance, was formed to examine the critical role of potassium in clinical practice. The goal of the Council was to assess the role of potassium in terms of current medical practice and future clinical applications. The primary outcome of the meeting was the development of guidelines for potassium replacement therapy. These guidelines represent a consensus of the Council members and are intended to provide a general approach to the prevention and treatment of hypokalemia.

Arrhythmias, Cardiac↗
PubMed2000

Cardiac remodeling--concepts and clinical implications: a consensus paper from an international forum on cardiac remodeling. Behalf of an International Forum on Cardiac Remodeling.

Cardiac remodeling is generally accepted as a determinant of the clinical course of heart failure (HF). Defined as genome expression resulting in molecular, cellular and interstitial changes and manifested clinically as changes in size, shape and function of the heart resulting from cardiac load or injury, cardiac remodeling is influenced by hemodynamic load, neurohormonal activation and other factors still under investigation. Although patients with major remodeling demonstrate progressive worsening of cardiac function, slowing or reversing remodeling has only recently become a goal of HF therapy. Mechanisms other than remodeling can also influence the course of heart disease, and disease progression may occur in other ways in the absence of cardiac remodeling. Left ventricular end-diastolic and end-systolic volume and ejection fraction data provide support for the beneficial effects of therapeutic agents such as angiotensin-converting enzyme (ACE) inhibitors and beta-adrenergic blocking agents on the remodeling process. These agents also provide benefits in terms of morbidity and mortality. Although measurement of ejection fraction can reliably guide initiation of treatment in HF, opinions differ regarding the value of ejection fraction data in guiding ongoing therapy. The role of echocardiography or radionuclide imaging in the management and monitoring of HF is as yet unclear. To fully appreciate the potential benefits of HF therapies, clinicians should understand the relationship between remodeling and HF progression. Their patients may then, in turn, acquire an improved understanding of their disease and the treatments they are given.

Adrenergic beta-Antagonists↗
PubMed2000

Estrogen is associated with improved survival in aging women with congestive heart failure: analysis of the vesnarinone studies.

OBJECTIVES: This study sought to evaluate the effects of postmenopausal estrogen use on mortality in aging women with congestive heart failure (CHF). BACKGROUND: The age-related increase in CHF mortality in women may be related to a menopause-associated increased incidence of coronary artery disease. In addition to inhibiting coronary atherosclerosis, estrogen may also have protective effects on cardiac myocytes independent of the coronary vasculature. We hypothesized that estrogen use is associated with improved survival in elderly women with CHF. METHODS: Associations between survival, estrogen use and patient characteristics were assessed in 1,134 women who were at least 50 years of age, had CHF and left ventricular ejection fraction (EF) < or =30% and were enrolled in one of three clinical trials of vesnarinone. RESULTS: All-cause 12-month mortality was 15.0% among the 237 estrogen users versus 27.1% among the 897 estrogen nonusers (p = 0.004 for unadjusted comparison of survival). Similar results were observed for cardiac mortality. Regression analysis demonstrated that estrogen use was independently associated with improved survival (relative risk of mortality = 0.68, 95% confidence interval 0.48 to 0.96, p = 0.03). Advanced age, low EF, New York Heart Association class IV CHF, Caucasian race and abnormal serum creatinine, sodium, potassium and transaminase were independently associated with increased mortality. CONCLUSIONS: Estrogen use among older women with CHF is associated with decreased overall and cardiac mortality.

Aged↗
PubMed2000

Heart failure: future treatment approaches.

Large-scale clinical trials of vasodilators with nitrates and hydralazine and with angiotensin-converting enzyme (ACE) inhibitors in the 1980s and early 1990s provided the first credible evidence that medical therapy can prolong survival in patients with chronic heart failure (CHF). Moreover, patients treated with ACE inhibitors required fewer hospitalizations for worsening heart failure (HF). Nonetheless, the prognosis in patients with HF remains bleak, and better therapies are urgently needed. Recently, beta-blockers and spironolactone have been shown to reduce mortality when added to ACE inhibitors, diuretics, and digoxin. Digoxin has a neutral effect on overall mortality but does reduce the rate of hospitalization. Angiotensin II receptor blockers (ARB) inhibit the AT1 angiotensin receptor, which mediates the deleterious effects of the renin-angiotensin system, and may provide advantages over ACE inhibitors or advantages when used in combination with ACE inhibitors. Newer drugs that interfere with other mechanisms that contribute to progression of heart failure are also under study. As new therapies prove effective in large populations, they lead to a mandate for polypharmacy. The long-term solution to this clinical problem is to develop sensitive and reliable markers that can predict response in individual patients or monitor effectiveness of therapy.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Relationship between arterial elasticity indices and carotid artery intima-media thickness.

Functional and structural changes of the arterial wall appear to serve as early hallmarks of the hypertensive disease process. Structural vascular changes can be studied by the determination of the intima-media wall thickness (IMT) at the carotid artery. The elastic behavior of the proximal and distal parts of the arterial tree can be assessed from noninvasively recorded radial artery waveforms. The aim of the study was to compare large (proximal, C1) and small (distal, C2) artery elasticity indices in two age-matched study groups with high- and low-normal blood pressure (BP) and to assess the relation between elasticity indices and IMT. A total number of 22 subjects with high-normal BP (40 +/- 2 years; BP, 147 +/- 2.5/84 +/- 1.5 mm Hg) and 22 matched controls with low-normal BP (40 +/- 2 years; BP, 123 +/- 1.9/69 +/- 1.5 mm Hg) were enrolled. The IMT was echographically determined at the common carotid artery by the leading-edge technique. Large artery (C1) and small artery (C2) elasticity indices were calculated from a third-order, four-element model of the arterial circulation. In the group with high-normal BP large and small artery elasticity indices were significantly decreased versus controls with low-normal BP (C1: 1.63 +/- 0.08 v 1.99 +/- 0.09 mL/mm Hg, P < .01; C2: 0.059 +/- 0.005 v 0.076 +/- 0.007 mL/ mm Hg, P < .05) and IMT increased significantly (0.607 +/- 0.039 v 0.516 +/- 0.027 mm, P < .05). Moreover, there was an inverse relationship between IMT and small artery elasticity index (r = -0.60, P = .004). In subjects with a high-normal BP there is already a change in the IMT of the carotid artery versus normotension. The IMT is related to the small artery elasticity index (C2).

Adult↗
PubMed2000

Felodipine improves left ventricular emptying in patients with chronic heart failure: V-HeFT III echocardiographic substudy of multicenter reproducibility and detecting functional change.

BACKGROUND: The echocardiographic substudy of the Vasodilator-Heart Failure Trial III (V-HeFT III) aimed to determine if felodipine treatment in patients with heart failure who were taking an angiotensin-converting enzyme inhibitor had a favorable effect on left ventricular (LV) structure and function. Earlier V-HeFT trials showed that hydralazine-isosorbide dinitrate improved ejection fraction (EF) and survival, whereas enalapril achieved greater survival with smaller increases in EF. Would the combination of a potent vasodilator and enalapril produce greater improvements in function and survival? METHODS AND RESULTS: Doppler-echocardiographic data were collected from 260 males with heart failure who were randomized to felodipine or a placebo. Mean intrasubject differences between baseline, at 3 months, and at 12 months were compared. Intersite and intrareader reproducibilities were measured from duplicate recordings and readings. At 3 months, no changes in ultrasound variables from baseline occurred in either group. At 12 months, felodipine patients achieved greater increases in EF, shortening of LV end-systolic length, and increases in stroke volume index. Reproducibility coefficients of variation were 7.4% (EF), 6.0% (end-diastolic length), and 13.0% (stroke volume index). CONCLUSIONS: The echocardiographic substudy showed that felodipine, added to heart failure therapy, increased EF, shortened end-systolic length, and increased stroke volume index. The changes were small and confirmed that reproducibility from multiple laboratories can be coordinated into a useful research tool.

Calcium Channel Blockers↗
PubMed2000

Plasma norepinephrine and atrial natriuretic peptide in heart failure: influence of felodipine in the third Vasodilator Heart Failure Trial. V-HeFT III investigators.

BACKGROUND: Reflex activation of the sympathetic nervous system by short-acting dihydropyridine calcium channel antagonists has been reported to harm hypertensive patients. Different neurohormonal profiles and their response to treatment may influence the effectiveness of dihydropyridine vasodilator treatment of heart failure. METHODS: Four hundred fifty men with left ventricular (LV) systolic dysfunction were administered standard heart failure treatment and felodipine extended release (ER) or placebo in the Vasodilator Heart Failure Trial III (V-HeFT III). Plasma norepinephrine (PNE) levels, atrial natriuretic peptide (ANP) levels, exercise capacity, LV ejection fraction (EF), cardiac dimensions and function, and arrhythmia frequency were measured. Hospital-free survival for baseline neurohormonal classes was assessed. RESULTS: Distributions of ANP and PNE levels at baseline in patients with heart failure of ischemic and nonischemic causes were virtually identical. ANP levels at baseline were inversely related to LVEF (r = -0.39; P = .0001), exercise duration (r = -0.19; P = .0001), and peak oxygen consumption (r = -0.27; P = .008) and directly related to LV (r = 0.23; P = .0006) and right ventricular dilatation (r = 0.23; P = .0008). The increase in ANP levels between baseline and 3 months (P = .02) and 1 year (P = .03) was significantly less in the felodipine-ER group than in the placebo group, but PNE levels did not differ between treatment groups. Hospital-free survival was directly related to baseline ANP (P = .0002) and PNE levels (P = .004). All-cause mortality was related to baseline PNE levels (P = .02) but not baseline ANP levels. CONCLUSION: Levels of ANP and PNE hormones are related to LV dysfunction, exercise performance, and hospital-free survival in heart failure and PNE levels are related to all-cause mortality. Treatment with felodipine ER did not adversely affect survival in any neurohormone subclass.

Administration, Oral↗
PubMed2000

Baseline demographics of the Valsartan Heart Failure Trial. Val-HeFT Investigators.

BACKGROUND: The Valsartan Heart Failure Trial (Val-HeFT) is the first large-scale randomized, multinational clinical study to assess the efficacy and safety of valsartan, an angiotensin II receptor blocker, added to conventional therapy, including angiotensin-converting enzyme inhibitors, in heart failure patients. A total of 5010 patients with an ejection fraction <40% have been randomized to either valsartan titrated to 160 mg b.i.d. or to placebo. AIMS: Baseline characteristics of patients in Val-HeFT are presented and compared with other major clinical trials in heart failure. METHODS: Baseline data were collected and summary statistics calculated. RESULTS: The study population has a mean age of 62.7 years and is 80% male, 90.3% white, 6.9% black, and 2.8% Asian. Antecedent coronary heart disease is reported in 57.2% of patients. Angiotensin-converting enzyme inhibitors are prescribed for 92.7% of patients, diuretics for 85.8%, digoxin for 67.3%, and beta-blockers for 35.6%. Subgroup comparisons by age, sex, race and ejection fraction quartile show small differences in baseline characteristics. CONCLUSION: Overall the Val-HeFT population is generally representative of the population of patients with mild to moderate heart failure in industrialized countries.

Adrenergic beta-Antagonists↗
PubMed2000

Cardiac protection: evolving role of angiotensin receptor blockers.

Congestive heart failure (HF) is a common and serious public health problem affecting approximately 5 million Americans. Recent treatment strategies have focused on attenuating the effects of angiotensin (Ang) II, which include vasoconstriction, sodium retention, sympathetic activation, and cell growth. Angiotensin-converting enzyme (ACE) inhibitors, which primarily block the systemic formation of Ang II, reduce HF-related morbidity and mortality rates. However, ACE inhibitors may not suppress Ang II activity over their entire dosing interval and, with long-term therapy, Ang II levels tend to return to normal. It is now known that Ang II can be formed independent of ACE by the action of enzymes such as chymase in local tissues, including the heart. Despite the established benefits of ACE inhibitor treatment, HF-related morbidity and mortality rates continue to increase because the aging of the population is placing more patients at risk of HF. By acting at the receptor level, Ang II receptor blockers (ARBs) should, at least theoretically, provide more "complete" Ang II blockade. Early evidence suggests that ARBs induce hemodynamic improvement in patients with HF and may reduce mortality rates. Because ACE inhibitors and ARBs block Ang II through fundamentally different mechanisms, the combination may provide additive therapeutic effects in patients with HF. Results from a pilot study suggest that the combination of an ACE inhibitor and valsartan results in a more thorough inhibition of Ang II and an additive improvement in cardiac hemodynamics. Clinical trials now in progress will elucidate the effects of combined ACE inhibitor and ARB therapy on HF-related morbidity and mortality rates.

Aged↗
PubMed2000

Rationale for angiotensin II receptor blocker therapy in chronic heart failure.

Inhibiting the synthesis of angiotensin II (Ang II) by angiotensin-converting enzyme (ACE) inhibitor treatment has long been established as the recommended therapy for heart failure (HF). As ACE inhibitors are only partially effective in blocking the formation of Ang II, additional treatment with selective Ang II receptor blockers (ARBs) promise additional benefits in patients with HF. This hypothesis is currently being evaluated in Val-HeFT, a large-scale, randomised, double-blind, placebo-controlled study on the effects of adding the highly selective ARB valsartan to usual therapy (diuretics, digoxin, beta-blockers, ACE inhibitors) for HF treatment.

Angiotensin II↗
PubMed2000

What does ATLAS really tell us about "high" dose angiotensin-converting enzyme inhibition in heart failure?

The Assessment of Treatment with Lisinopril and Survival (ATLAS) results have been widely quoted by proponents advocating the use of "high" doses of angiotensin-converting enzyme (ACE) inhibitors for the treatment of heart failure. In ATLAS, however, the relative benefits of "high" versus "low" dose ACE inhibition were small. Intermediate doses of ACE inhibitors proven effective in previous placebo-controlled trials provide benefit that appears likely to equal or exceed the benefit from "high" dose ACE inhibition. Therefore, we recommend that physicians continue to prescribe ACE inhibitors for patients with heart failure based on the target doses used in the placebo-controlled trials and not on the "high" dose target used in ATLAS.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1999

Augmented short- and long-term hemodynamic and hormonal effects of an angiotensin receptor blocker added to angiotensin converting enzyme inhibitor therapy in patients with heart failure. Vasodilator Heart Failure Trial (V-HeFT) Study Group.

BACKGROUND: ACE inhibitors may not adequately suppress deleterious levels of angiotensin II in patients with heart failure. An angiotensin receptor blocker added to an ACE inhibitor may exert additional beneficial effects. METHODS AND RESULTS: Eighty-three symptomatic stable patients with chronic heart failure receiving long-term ACE inhibitor therapy were randomly assigned to double-blind treatment with valsartan 80 mg BID, valsartan 160 mg BID, or placebo while receiving their usual ACE inhibitor therapy. Studies were performed before and after the first dose of the test drug and again after 4 weeks of therapy. A single dose of lisinopril was administered during study days to ensure sustained ACE inhibition. Compared with placebo, the first dose of valsartan 160 mg resulted in a significantly greater reduction in pulmonary capillary wedge pressure at 3, 4, and 8 hours and during the prespecified 4- to 8-hour interval after the dose and in systolic blood pressure at 2, 3, 6, 8, and 12 hours and 4 to 8 hours after the dose. A pressure reduction from valsartan 80 mg did not achieve statistical significance. After 4 weeks of therapy, net reductions in 0-hour trough pulmonary capillary wedge pressure (-4.3 mm Hg; P=0. 16), pulmonary artery diastolic pressure (-4.7 mm Hg; P=0.013), and systolic blood pressure (-6.8 mm Hg; P=0.013) were observed in the valsartan 160 mg group compared with placebo. After 4 weeks of therapy, plasma aldosterone was reduced by valsartan 80 mg BID (-52. 1 pg/mL; P=0.001) and 160 mg BID (-47.8 pg/mL; P<0.001) compared with placebo, and there was a trend for a reduction in plasma norepinephrine (-97 pg/mL; P=0.10). Seventy-four of the 83 patients completed the trial. CONCLUSIONS: Physiologically active levels of angiotensin II persist during standard long-term ACE inhibitor therapy.

Aged↗
PubMed1999

Localization of changes in beta-actin expression in remodeled canine myocardium.

Beta-actin is a cytoskeletal protein that has been implicated as a potentially important mediator of the growth, signaling, migration, and remodeling of cells. Beta-actin is upregulated in remodeling myocardium in response to either pressure or volume overload. The cellular localization of this response has, however, not been determined and is a necessary first step to begin to clarify the role of beta-actin in myocardial remodeling. Here we demonstrate that beta -actin protein was confined primarily to the cardiac interstitium using immunofluorescent and immunohistochemical staining. Furthermore, both staining and immunoblotting showed markedly increased beta-actin protein in myocardium within 24 h of either regional left ventricular damage or chronic volume overload. More importantly, this increase persisted up to 90 days in both models. Double staining showed co-localization of beta-actin protein and von Willebrand factor, a specific endothelial cell marker. These results suggest that increased beta-actin expression predominantly localized in cardiac interstitial cells, including endothelial cells. The increased beta-actin could be due to either proliferation of the interstitial cells or upregulation of the beta-actin gene.

Actins↗