Islet Transplantation under the Kidney Capsule Corrects the Defects in Glycogen Metabolism in Both Liver and Muscle of Streptozocin-Diabetic Rats

Insulin-deficient rats are characterized by multiple defects in the pathway of glycogen synthesis and breakdown in both liver and skeletal muscle. The aim of this study was to clarify whether islet transplantation under the kidney capsule, which is associated with delivery of insulin into the peripheral circulation, is able to normalize glycogen metabolism in liver and muscle of streptozotocin-diabetic rats. Three groups of male Lewis rats were studied under fasting condition: controls, untreated diabetics, and islet transplanted diabetics. Glycogen content, glucose-6-phosphate concentration, and glycogen synthase activity were measured in both liver and skeletal muscle. Untreated diabetic rats were characterized by an increase in glycogen content of 178% and a reduction of glucose-6-phosphate level of 50%. Both glycogen and glucose-6-phosphate contents were restored to normal in transplanted diabetic rats. Active glycogen synthase (0.35 ± 0.1 nmol/min/mg) and activity ratio (0.22 ± 0.04) were significantly impaired compared with controls (0.99 ± 0.2 nmol/min/mg and 0.43 ± 0.06, respectively) and were normalized by islet transplantation. In the skeletal muscle, glycogen content was similar in the three groups of animals, whereas muscle glucose-6-phosphate level was reduced by 28% and glycogen synthase was in a less active state in the untreated diabetic rats. Both the glucose-6-phosphate concentration and the kinetic profile of glycogen synthase were normalized by islet transplantation. In conclusion, islet transplantation under the kidney capsule corrects the diabetes-induced abnormalities in glycogen and glucose-6-phosphate content and glycogen synthase activity in both liver and skeletal muscle.

Anabolic/Catabolic Imbalance in Chronic Heart Failure

A metabolic imbalance between anabolic drive and catabolic forces is commonly observed in chronic heart failure (CHF) patients, with the latter prevailing over anabolic hormones. Moreover, anabolic deficiencies are independent markers of poor prognosis. This finding represents a solid background for the implementation of therapeutic trials based on replacement therapy. The somatotropic axis (GH/IGF-1) is the most powerful anabolic axis of the body and its decline is related with a poor outcome and a worse clinical status. Growth hormone (GH) administration may enter the therapeutic arena as adjunctive treatment in patients affected by CHF and GH/IGF-1 deficiency. The T.O.S.CA. project aims at investigating the relationship between CHF and hormonal deficiency.

Growth hormone replacement delays the progression of chronic heart failure combined with growth hormone deficiency: an extension of a randomized controlled single-blind study

OBJECTIVES

This study sought to evaluate the efficacy and safety of long-term growth hormone (GH) replacement therapy in GH-deficient patients with chronic heart failure (CHF).

BACKGROUND

Recent evidence indicates that growth hormone deficiency (GHD) affects as many as 40% of patients with CHF, and short-term GH replacement causes functional benefit. Whether long-term GH replacement also affects CHF progression is unknown.

METHODS

The study is an extension of a previous randomized, controlled single-blind trial that screened 158 consecutive CHF patients (New York Heart Association classes II to IV) and identified 63 who had GHD by the growth hormone releasing hormone plus arginine test. Fifty-six patients were randomized to receive either GH therapy or standard CHF therapy. Patients were evaluated at baseline and after a 4-year follow-up. The primary endpoint was peak oxygen consumption (VO2). Secondary endpoints included left ventricular (LV) ejection fraction and volumes, serum amino terminal fragment of the pro-hormone brain-type natriuretic peptide, quality of life, and safety.

RESULTS

Seventeen patients in the GH group and 14 in the control group completed the study. In the GH group, peak VO2 improved over the 4-year follow-up. The treatment effect was 7.1 ± 0.7 ml/kg/min versus -1.8 ± 0.5 ml/kg/min in the GH and control groups, respectively. At 4 years, LV ejection fraction increased by 10 ± 3% in the GH group, whereas it decreased by 2 ± 5% in control patients. The treatment effect on LV end-systolic volume index was -22 ± 6 ml and 8 ± 3 ml/m(2) in the GH and control groups, respectively (all p < 0.001). No major adverse events were reported in the patients who received GH.

CONCLUSIONS

Although this is a preliminary study, the finding suggests a new therapeutic approach to a large proportion of GHD patients with CHF.

SOCS1 gene transfer accelerates the transition to heart failure through the inhibition of the gp130/JAK/STAT pathway

AIMS

The suppressors of cytokine signalling (SOCS) are identified inhibitors of cytokine and growth factor signalling that act via the Janus kinase (JAK) signal transducers and activators of transcription (STAT) pathways. Aberrant JAK/STAT signalling promotes progression from hypertrophy to heart failure. Little information is available concerning the role of SOCS in the transition from hypertrophy to heart failure. To this aim, we investigated the effects of SOCS1 overexpression obtained by in vivo adeno-associated gene transfer using an aortopulmonary cross-clamping technique in a chronic pressure-overload cardiac rat model.

METHODS AND RESULTS

Rats were randomized into four groups: sham-operated (n = 18), aortic banding (AB) (n = 18), AB + viral vector encoding for haemoagglutinin (AB + HA, n = 16), and AB + viral vector encoding for SOCS1 (AB + SOCS1, n = 18). Echocardiographic and haemodynamic measurements were performed 15 weeks after banding. While SOCS3 was upregulated during the hypertrophic phase, SOCS1 transcript levels increased significantly between 15 and 20 weeks. Remodelling was markedly worse in AB + SOCS1, showed larger left ventricular internal dimensions (+16%), higher end-diastolic pressures (+57%) and wall stress (+45%), and reduced fractional shortening (-32%) compared with AB + HA; apoptotic rate was increased three-fold and the gp130 pathway was inhibited. Ex vivo experiments showed that mechanical stretch upregulated SOCS1 expression, which was in turn attenuated by tumour necrosis factor-α (TNF-α) inhibition.

CONCLUSION

Enhanced SOCS1 myocardial signalling is associated with accelerated transition from hypertrophy to failure in an established model of pressure overload. SOCS1 may represent an attractive target for the prevention of heart failure progression.

Cardiovascular abnormalities in Klinefelter syndrome

BACKGROUND

Several epidemiological studies have demonstrated an increased mortality from cardiovascular causes in patients with Klinefelter Syndrome (KS). Little information is available about the nature of the underlying cardiovascular abnormalities. Aim of the study was to investigate exercise performance, left ventricular architecture and function, vascular reactivity, and carotid intima-media thickness in a group of patients with KS.

MATERIALS AND METHODS

Sixty-nine patients with KS and 48 age-matched controls participated in our population-controlled study. Forty-eight Klinefelter subjects were on testosterone treatment at the time of the investigation while 21 were naive and underwent a complete Doppler echocardiographic examination, a cardiopulmonary exercise test as well as a vascular study including measures of carotid intima-media thickness and endothelial function with flow-mediated dilation of the brachial artery. Patients with KS on testosterone therapy (n=48) were also matched against a population of men with treated secondary hypogonadism (n=21).

RESULTS

Patients with KS exhibited a wide array of cardiovascular abnormalities including left ventricular diastolic dysfunction, reduced maximal oxygen consumption (p<0.01), increased intima-media thickness (p<0.05) (-34% and +42% vs. controls, respectively) and a high prevalence of chronotropic incompetence (55% of patients, p<0.01). No significant difference was found between treated and untreated KS in variance with men treated for secondary hypogonadism.

CONCLUSION

Left ventricular diastolic dysfunction, impaired cardiopulmonary performance, chronotropic incompetence, and increased intima-media thickness suggest that cardiovascular abnormalities are a common finding in KS that is not reversed by testosterone replacement therapy and may represent the pathophysiological underpinnings of the increased risk of dying from heart disease.

The T.O.S.CA. Project: research, education and care

Despite recent and exponential improvements in diagnostic-therapeutic pathways, an existing "GAP" has been revealed between the "real world care" and the "optimal care" of patients with chronic heart failure (CHF). We present the T.O.S.CA. Project (Trattamento Ormonale dello Scompenso CArdiaco), an Italian multicenter initiative involving different health care professionals and services aiming to explore the CHF "metabolic pathophysiological model" and to improve the quality of care of HF patients through research and continuing medical education.

Metformin prevents the development of chronic heart failure in the SHHF rat model

Insulin resistance is a recently identified mechanism involved in the pathophysiology of chronic heart failure (CHF). We investigated the effects of two insulin-sensitizing drugs (metformin and rosiglitazone) in a genetic model of spontaneously hypertensive, insulin-resistant rats (SHHF). Thirty SHHF rats were randomized into three treatment groups as follows: 1) metformin (100 mg/kg per day), 2) rosiglitazone (2 mg/kg per day), and 3) no drug. Ten Sprague-Dawley rats served as normal controls. At the end of the treatment period (12 months), the cardiac phenotype was characterized by histology, echocardiography, and isolated perfused heart studies. Metformin attenuated left ventricular (LV) remodeling, as shown by reduced LV volumes, wall stress, perivascular fibrosis, and cardiac lipid accumulation. Metformin improved both systolic and diastolic indices as well as myocardial mechanical efficiency, as shown by improved ability to convert metabolic energy into mechanical work. Metformin induced a marked activation of AMP-activated protein kinase, endothelial nitric oxide synthase, and vascular endothelial growth factor and reduced tumor necrosis factor-α expression and myocyte apoptosis. Rosiglitazone did not affect LV remodeling, increased perivascular fibrosis, and promoted further cardiac lipid accumulation. In conclusion, long-term treatment with metformin, but not with rosiglitazone, prevents the development of severe CHF in the SHHF model by a wide-spectrum interaction that involves molecular, structural, functional, and metabolic-energetic mechanisms.

Effects of a nutraceutical combination (berberine, red yeast rice and policosanols) on lipid levels and endothelial function randomized, double-blind, placebo-controlled study

BACKGROUND AND AIMS

Some nutraceuticals are prescribed as lipid-lowering substances. However, doubts remain about their efficacy. We evaluated the effects of a nutraceutical combination (NC), consisting of 500 mg berberine, 200mg red yeast rice and 10mg policosanols, on cholesterol levels and endothelial function in patients with hypercholesterolemia.

METHODS AND RESULTS

In this single centre, randomized, double-blind, placebo-controlled study, 50 hypercholesterolemic patients (26 males and 24 females, mean age 55±7 years, total cholesterol 6.55±0.75 mmol/l, BMI 28±3.5) were randomized to 6 weeks of treatment with a daily oral dose of NC (25 patients) or placebo (25 patients). In a subsequent open-label extension of 4 weeks, the whole sample received NC. The main outcome measure was decrease total cholesterol (C) levels in the NC arm. Secondary outcome measures were decreased low-density lipoprotein cholesterol (LDL-C) and triglyceride levels, and improved endothelial-dependent flow-mediated dilation (FMD) and insulin sensitivity in relation to NC. Evaluation of absolute changes from baseline showed significant reductions in NC versus placebo for C and LDL-C (C: -1.14±0.88 and -0.03±0.78 mmol/l, p<0.001; LDL-C: -1.06±0.75 and -00.4±0.54 mmol/l, p<0.001), and a significant improvement of FMD (3±4% and 0±3% respectively, p<0.05). After the extension phase, triglyceride levels decreased significantly from 1.57±0.77 to 1.26±0.63 mmol/l, p<0.05 and insulin sensitivity improved in a patient subgroup with insulin resistance at baseline (HOMA: from 3.3±0.4 to 2.5±1.3, p<0.05). No adverse effect was reported.

CONCLUSIONS

This NC reduces cholesterol levels. The reduction is associated with improved endothelial function and insulin sensitivity.

The uncontrolled clinical trial: scientific, ethical, and practical reasons for being

According to principles of clinical trial design, the demonstration of efficacy of a new treatment is based on comparing the response in the treated group with that of a control group receiving placebo or another active treatment. The need for a control group is also recommended by the major international institutions that govern the ethics and the practice of clinical research. Despite these principles and recommendations, inspection of a purposive sample of ongoing clinical trials listed in the NIH registry ( http://ClinicalTrials.gov ) reveals that as many as one-third of trials are uncontrolled. Since these trials were approved through a formal evaluation by ethics committees, the lack of adequate control was not perceived as a major deficiency in the study design. Most uncontrolled trials belong to the oncology/hematology area. If two extreme disease conditions for nature and progression are analyzed, such as acute myeloid leukemia (AML) and chronic heart failure (CHF), the difference in the prevalence of uncontrolled trials is very striking. The number of uncontrolled trials is only 13% in CHF, whereas it reaches 66% in the AML group. I believe that the underlying disease condition plays a primary role in orienting the design of the study: oncology and hematology may be fields in which uncontrolled studies are common, whereas in other fields, e.g., cardiology, this phenomenon can be reduced. Within the limitations of the selection process of the examined trials, the current analysis indicates that the clinical trial reality does not strictly follow experimental design theory and official recommendations.

Impaired diastolic function in naïve untreated human immunodeficiency virus infected patients

AIM

To evaluate cardiac function and structure in untreated human immunodeficiency virus (HIV) patients without clinical evidence of cardiovascular disease.

METHODS

Fifty-three naïve untreated HIV-infected patients and 56 healthy control subjects underwent clinical assessment, electrocardiography (ECG) and echocardiography, including tissue doppler imaging. Moreover, a set of laboratory parameters was obtained from all subjects, including HIV-RNA plasma levels, CD4 cell counts and tumor necrosis factor-α levels.

RESULTS

The two groups showed normal ECG traces and no differences regarding systolic morphologic parameters. In contrast, a higher prevalence of left ventricular diastolic dysfunction (abnormal relaxation or pseudonormal filling pattern) was found in the HIV patients (36% vs 9% in patients and controls, respectively, P <0.001).

CONCLUSION

Subclinical cardiac abnormalities appear in an early stage of the HIV infection, independent of antiretroviral therapy. The data suggest that HIV per se plays a role in the genesis of diastolic dysfunction.

Impaired endothelial- and nonendothelial-mediated vasodilation in patients with acute or chronic hypothyroidism

OBJECTIVE

Vascular dysfunction and accelerated atherosclerosis are prominent features of hypothyroidism. The relative roles of thyroid hormone (TH) deficiency and the associated vascular risk conditions are still unclear. We studied the impact of acute and chronic hypothyroidism on vascular reactivity.

PATIENTS

We studied 12 patients with chronic primary hypothyroidism (cHY; TSH: 52 +/- 14 mU/l), seven patients with acute hypothyroidism secondary to total thyroidectomy (aHY; TSH: 97 +/- 24) and 13 healthy subjects (TSH: 1.2 +/- 0.5).

MEASUREMENTS

We measured forearm blood flow (FBF) using plethysmography during intra-brachial infusion of: acetylcholine (ACh), sodium nitroprusside (NP) and norepinephrine (NE). We also measured serum C-reactive protein (CRP), TNF-alpha, asymmetric dimethylarginine (ADMA) and the forearm balance of nitric oxide (NO) during ACh infusion.

RESULTS

As compared with the controls, the vasodilatory response to ACh was reduced in cHY (P = 0.001) and aHY (P = 0.04), as was the forearm release of NO (P < 0.05). During NP infusion, FBF rose to 24 +/- 2 ml/dl/min in the controls and to significantly lower values in cHY (12 +/- 1; P = 0.001) and aHY (15 +/- 2; P = 0.004). NE-induced vasoconstriction was similar in the controls and aHY, but blunted in cHY. Serum CRP, TNF-alpha and ADMA were not different in the three groups.

CONCLUSIONS

(i) Hypothyroidism associates with endothelial and nonendothelial mediated vascular dysfunction; (ii) these defects are evident even after short-term hypothyroidism, indicating that TH deficiency per se is sufficient to alter vascular homeostasis; and (iii) chronic, but not acute, hypothyroidism impairs the vasoconstrictory effect of NE in the resistance vessels.

Insulin-like growth factor-1 protects from vascular stenosis and accelerates re-endothelialization in a rat model of carotid artery injury

BACKGROUND

IGF-1 is a potent mitogen for vascular smooth muscle cells, but exerts protective effects on endothelial cells that may trigger antiatherogenic mechanisms.

OBJECTIVES

This study was designed to test the hypothesis that an IGF-1 excess following arterial injury prevents neointima formation and vascular stenosis.

METHODS

Rats were subjected to carotid balloon injury and treated with IGF-1 (1.2 mg kg(-1) per die) or saline for 10 days.

RESULTS

In IGF-1 treated animals, high tissue levels of eNOS, Akt and its phosphorylated form were found, confirming activation of IGF-1-dependent signaling pathways. IGF-1 markedly reduced neointima formation and post-injury arterial stenosis. IGF-1 exerted proliferative and anti-apoptotic effects in the media of injured carotids, but inhibited mitotic activity and induced apoptosis in the neointima. Furthermore, IGF-1 stimulated mobilization of progenitor endothelial cells and re-endothelialization of the injured arteries. L-NAME administration inhibited IGF-1 vasculoprotective effects.

CONCLUSIONS

IGF-1 attenuates post-injury carotid stenosis by exerting differential effects in the neointima and tunica media with regard to the key components of the response to injury. The data point to a novel role of IGF-1 as a potent vasculoprotective factor.

Growth hormone deficiency in patients with chronic heart failure and beneficial effects of its correction

CONTEXT

A reduced activity of the GH/IGF-I axis in chronic heart failure (CHF) has been described by several independent groups and is associated with poor clinical status and outcome.

OBJECTIVE

The aim of the current study was to investigate the prevalence of GH deficiency in a patient population with CHF and evaluate the cardiovascular effects of GH replacement therapy.

DESIGN AND SETTING

The randomized, single-blind, controlled trial was conducted at the Federico II University.

PARTICIPANTS

One hundred fifty-eight patients with CHF, New York Heart Association class II-IV, underwent a GH stimulation test. Sixty-three patients satisfied the criteria for GH deficiency, and 56 of them were enrolled in the trial.

INTERVENTION

The treated group (n = 28) received GH at a replacement dose of 0.012 mg/kg every second day (approximately 2.5 IU).

MAIN OUTCOMES MEASURES

Changes in physical performance and various cardiovascular indexes were measured.

RESULTS

GH replacement therapy improved quality of life score (from 46 +/- 5 to 38 +/- 4; P < 0.01), increased peak oxygen uptake and exercise duration (from 12.9 +/- .9 to 14.5 +/- 1 ml/kg x min and from 520 +/- 36 to 586 +/- 43 sec, respectively; P < 0.01), and flow-mediated vasodilation (from 8.8 +/- 1.3 to 12.7 +/- 1.2%; P < 0.01). GH increased left ventricular ejection fraction (from 34 +/- 2 to 36 +/- 2%; P < 0.01) and reduced circulating N-terminal pro-brain natriuretic peptide levels (from 3201 +/- 900 to 2177 +/- 720 pg/ml; P = 0.006). No significant changes from baseline were observed in controls.

CONCLUSIONS

As many as 40% of patients with CHF are GH deficient. GH replacement therapy in these patients improves exercise capacity, vascular reactivity, left ventricular function, and indices of quality of life.

Vascular smooth muscle cell dysfunction in patients with migraine

BACKGROUND

Migraine is associated with increased risk of cardiovascular disease, but the mechanisms are unclear.

OBJECTIVE

To investigate the activity of endothelial and vascular smooth muscle cells (VSMCs) in patients with migraine.

METHODS

Case-control study of 12 patients with migraine without aura and 12 matched healthy control subjects. Endothelial and VSMC components of vascular reactivity were explored by plethysmography measurement of forearm blood flow (FBF) during infusions of vasoactive agents into the brachial artery. Forearm production of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) was also quantified.

RESULTS

In patients with migraine, the vasodilating effect of acetylcholine (ACh), an endothelium-dependent vasodilator, was markedly reduced (p < 0.001 by analysis of variance). In response to the highest dose of ACh, FBF rose to 8.6 +/- 2.2 in patients with migraine and to 22.7 +/- 3.0 mL x dL(-1) x min(-1) in controls (p = 0.001). The dose-response curve to nitroprusside, a vasodilator directly acting on VSMCs, was depressed in patients with migraine (p < 0.001 by analysis of variance). The maximal response of FBF to nitroprusside was 12.1 +/- 2.0 in patients with migraine and 24.1 +/- 1.8 mL x dl(-1) x min(-1) in controls (p < 0.001). During ACh infusion, NO release from the endothelium was similar in patients and controls. In contrast, there was a marked release of cGMP from VSMCs in controls, but not in patients with migraine (-1.9 +/- 2.2 in patients with migraine and -19.1 +/- 5.4 nmol x dL(-1) x min(-1) in controls; p = 0.03).

CONCLUSIONS

Patients with migraine are characterized by a distinct vascular smooth muscle cell dysfunction, revealed by impaired cyclic guanosine monophosphate and hemodynamic response to nitric oxide.

Usefulness of NT-proBNP in the assessment of patients with aortic or mitral regurgitation

BACKGROUND

Recent application of brain natriuretic peptide and N-terminal prohormone brain natriuretic peptide (NT-proBNP) in cardiac valvular disease is very promising.

AIMS

To test the usefulness of NT-proBNP in the assessment of patients with aortic or mitral regurgitation.

PATIENTS AND METHODS

Sixty-seven patients - 23 with aortic and 12 with mitral regurgitation vs. 32 controls - were examined by color Doppler echocardiography, cardiopulmonary exercise testing, Minnesota Living with Heart Failure Questionnaire (MLWHFQ) and plasma NT-proBNP assay at rest (T0) and after maximal physical exercise (T1).

RESULTS

NT-proBNP was significantly higher in patients than in controls, both at T0 (298 +/- 85 vs. 46 +/- 11 pg/ml; P < 0.01) and at T1 (366 +/- 106 vs. 50 +/- 12 pg/ml; P < 0.01). MLWHFQ score was significantly higher in patients (19 +/- 3 vs. 1 +/- 0.6; P < 0.001) with a significant inverse correlation with VO2max (r = -0.538, P < 0.001) and a direct correlation with NT-proBNP (T0: r = 0.415, P < 0.01; T1: r = 0.458, P < 0.01). NT-proBNP was inversely correlated with VO2max (T0: r = -0.444, P < 0.001; T1:r = -0.428, P < 0.001) and directly correlated with left atrial diameter (T0: r = 0.370, P < 0.01; T1: r = 0.409, P = 0.001), and left ventricular mass index (r = 0.279, P < 0.01, and r = 0.272, P < 0.01). No correlations were found between echocardiographic parameters of valvular disease severity and VO2max, NT-proBNP and MLWHFQ.

CONCLUSIONS

NT-proBNP is useful in the assessment of the cardiac functional damage secondary to mitral and aortic regurgitation.

Doxorubicin-induced cardiomyopathy treated with carvedilol

Even today, heart failure due to doxorubicin-induced dilated cardiomyopathy seems to have a poor prognosis, as it is often irreversible and relatively unresponsive to standard medical treatment. This paper describes the first case of a patient complaining of severe symptoms of congestive heart failure due to doxorubicin-induced dilated cardiomyopathy unresponsive to standard medical treatment (digoxin, diuretics, and angiotensin-converting enzyme inhibitor), who showed complete clinical recovery and significant improvement of left ventricular dysfunction after carvedilol treatment. It also illustrates the possibility that carvedilol may be a first-choice drug for the treatment of this disease.

Long-term cardiovascular effects of levothyroxine therapy in young adults with congenital hypothyroidism

CONTEXT

Congenital hypothyroidism (CH) is the most prevalent endocrine disorder in the newborn and is routinely treated with life-long levothyroxine replacement therapy. Although several studies have demonstrated that such therapy may impact on the cardiovascular system, little is known with regard to the effects of long-term levothyroxine administration in patients with CH.

OBJECTIVE

The aim of the current study was to evaluate whether long-term levothyroxine replacement therapy in young adults with CH is associated with cardiovascular abnormalities.

PATIENTS AND METHODS

Thirty young adults with CH aged 18.1 +/- 0.2 yr and 30 age- and sex-matched controls underwent cardiac and carotid Doppler ultrasound and symptom-limited cardiopulmonary exercise testing. Hypothyroidism was diagnosed by neonatal screening, and levothyroxine treatment was initiated within the first month of life and carefully adjusted to maintain TSH levels in the normal range and free T(4) in the high-normal range.

RESULTS

Compared with controls, hypothyroid patients exhibited left ventricular diastolic dysfunction, impaired exercise capacity, and increased intima-media thickness. At multiple regression analysis, the number of episodes of plasma TSH levels less than 0.5 mU/liter and greater than 4.0 mU/liter from the age of 1 yr onward, and mean TSH plasma levels during puberty were independent predictors of diastolic filling and cardiopulmonary performance indexes (multiple r values: 0.61-0.75).

CONCLUSIONS

Long-term levothyroxine treatment in young adults with congenital hypothyroidism is associated with impaired diastolic function and exercise capacity and increased intima-media thickness.

Enhancement of vascular endothelial function by recombinant human thyrotropin

CONTEXT

The cardiovascular consequences of thyroid diseases are attributed to the altered secretion of thyroid hormones. The possibility that TSH also affects the cardiovascular system has been poorly explored. Endothelial cells and vascular smooth muscle cells possess TSH receptors.

OBJECTIVE

The study was designed to determine whether TSH exerts any effect on vascular homeostasis.

SUBJECTS AND METHODS

Two different double-blind, controlled studies were performed, one in eight healthy volunteers and the other in six thyroidectomized patients. Recombinant human (rh) TSH (or saline) was infused intrabrachially (1 mU/min) to raise TSH to severe hypothyroidism levels (approximately 100 microU/ml). Endothelium-dependent and -independent vasodilation was tested by intraarterial infusion of acetylcholine and sodium nitroprusside, respectively, and forearm blood flow was measured by plethysmography.

RESULTS

Endothelium-dependent vasodilation was potentiated by rhTSH (P < 0.05 for the treatment effect; general linear model). The dynamics of the response was also profoundly affected by rhTSH because the dose-response curve was much steeper than in controls (P < 0.02 for the interaction between TSH and acetylcholine). rhTSH had no effect on endothelium-independent vasodilation (P = NS for both treatment and interaction). During rhTSH infusion, free T(3) levels increased slowly from 2.3 +/- 0.2 to 3.6 +/- 0.2 pg/ml. In thyroidectomized patients, rhTSH potentiated endothelium-mediated vasodilation to an extent similar to that of healthy subjects (P = 0.05 for the treatment effect and P = 0.01 for the interaction), without affecting the response to nitroprusside. In these patients, thyroid hormones remained unchanged during rhTSH infusion.

CONCLUSIONS

rhTSH exerts marked effects on the resistance vessels by enhancing endothelial-mediated vasodilation, independent of changes in thyroid hormone concentration.

Effects of growth hormone on exercise capacity and cardiopulmonary performance in patients with chronic heart failure

BACKGROUND

Because GH exerted beneficial effects in various experimental models of heart failure, we investigated the effects of GH on physical exercise capacity and cardiopulmonary performance in patients with dilated cardiomyopathy and chronic heart failure (CHF).

METHODS

Twenty-two patients with CHF (New York Heart Association functional class II-III) underwent spirometry and a symptom-limited, cardiopulmonary exercise testing before and after 3 months of GH (n = 11; seven males; seven idiopathic; 57 +/- 11 yr; 4 IU sc every other day) or placebo (n = 11; eight males; six idiopathic; 54 +/- 10 yr) administration, in a randomized, double-blind trial. Background CHF therapy remained unchanged.

RESULTS

GH, but not placebo, increased IGF-I serum concentration (from 144 +/- 35 to 293 +/- 58 ng/ml; P < 0.005) and improved New York Heart Association functional class (from 2.4 +/- 0.5 to 1.8 +/- 0.4; P < 0.005), exercise duration (from 831 +/- 273 to 925 +/- 266 sec; P < 0.005), peak power output (from 245 +/- 127 to 280 +/- 132 W; P < 0.05), peak minute ventilation (from 52.5 +/- 16.1 to 61.3 +/- 17.3 liters/min; P < 0.05), peak oxygen consumption (from 19.8 +/- 5.6 to 25.1 +/- 5.6 ml/kg.min; P < 0.005), and anaerobic threshold (from 14.9 +/- 4.8 to 20.0 +/- 4.5 ml/kg.min; P < 0.005) without affecting lung function parameters. Furthermore, the slope of the relationship between minute ventilation and pulmonary carbon dioxide production (ventilatory efficiency) decreased from 34.7 +/- 5.1 to 31.7 +/- 5.3 (P < 0.005), whereas the slope of the relation between percent predicted heart rate reserve used and percent observed metabolic reserve used (chronotropic index) rose from 0.57 +/- 0.20 to 0.69 +/- 0.18 (P < 0.005).

CONCLUSION

Given the predictive value of physical exercise capacity and cardiopulmonary performance in CHF progression, these data provide additional insights into the mechanisms by which GH may potentially benefit CHF patients.

Acute effects of triiodothyronine on endothelial function in human subjects

CONTEXT

Thyroid hormone regulates several cardiovascular functions, and low T(3) levels are frequently associated with cardiovascular diseases. Whether T(3) exerts any acute and direct effect on endothelial function in humans is unknown.

OBJECTIVE

Our objective was to clarify whether acute changes in serum T3 concentration affect endothelial function.

DESIGN, SETTING, AND SUBJECTS

Ten healthy subjects (age, 24 +/- 1 yr) participated in a double-blind, placebo-controlled trial at a university hospital.

INTERVENTIONS

T3 (or placebo) was infused for 7 h into the brachial artery to raise local T3 to levels observed in moderate hyperthyroidism. Vascular reactivity was tested by intraarterial infusion of vasoactive agents.

MAIN OUTCOME MEASURES

We assessed changes in forearm blood flow (FBF) measured by plethysmography.

RESULTS

FBF response to the endothelium-dependent vasodilator acetylcholine was enhanced by T3 (P = 0.002 for the interaction between T3 and acetylcholine). The slopes of the dose-response curves were 0.41 +/- 0.06 and 0.23 +/- 0.04 ml/dl x min/microg in the T3 and placebo study, respectively (P = 0.03). T3 infusion had no effect on the FBF response to sodium nitroprusside. T3 potentiated the vasoconstrictor response to norepinephrine (P = 0.006 for the interaction). Also, the slopes of the dose-response curves were affected by T3 (1.95 +/- 0.77 and 3.83 +/- 0.35 ml/dl x min/mg in the placebo and T3 study, respectively; P < 0.05). The increase in basal FBF induced by T3 was inhibited by NG-monomethyl-L-arginine.

CONCLUSIONS

T3 exerts direct and acute effects on the resistance vessels by enhancing endothelial function and norepinephrine-induced vasoconstriction. The data may help clarify the vascular impact of the low T3 syndrome and point to potential therapeutic strategies.

Adenoviral gene transfer of Akt enhances myocardial contractility and intracellular calcium handling

The serine-threonine kinase Akt/PKB mediates stimuli from different classes of cardiomyocyte receptors, including the growth hormone/insulin like growth factor and the beta-adrenergic receptors. Whereas the growth-promoting and antiapoptotic properties of Akt activation are well established, little is known about the effects of Akt on myocardial contractility, intracellular calcium (Ca(2+)) handling, oxygen consumption, and beta-adrenergic pathway. To this aim, Sprague-Dawley rats were subjected to a wild-type Akt in vivo adenoviral gene transfer using a catheter-based technique combined with aortopulmonary crossclamping. Left ventricular (LV) contractility and intracellular Ca(2+) handling were evaluated in an isolated isovolumic buffer-perfused, aequorin-loaded whole heart preparations 10 days after the surgery. The Ca(2+)-force relationship was obtained under steady-state conditions in tetanized muscles. No significant hypertrophy was detected in adenovirus with wild-type Akt (Ad.Akt) versus controls rats (LV-to-body weight ratio 2.6+/-0.2 versus 2.7+/-0.1 mg/g, controls versus Ad.Akt, P, NS). LV contractility, measured as developed pressure, increased by 41% in Ad.Akt. This was accounted for by both more systolic Ca(2+) available to the contractile machinery (+19% versus controls) and by enhanced myofilament Ca(2+) responsiveness, documented by an increased maximal Ca(2+)-activated pressure (+19% versus controls) and a shift to the left of the Ca(2+)-force relationship. Such increased contractility was paralleled by a slight increase of myocardial oxygen consumption (14%), while titrated dose of dobutamine providing similar inotropic effect augmented oxygen consumption by 39% (P<0.01). Phospholamban, calsequestrin, and ryanodine receptor LV mRNA and protein content were not different among the study groups, while sarcoplasmic reticulum Ca(2+) ATPase protein levels were significantly increased in Ad.Akt rats. beta-Adrenergic receptor density, affinity, kinase-1 levels, and adenylyl cyclase activity were similar in the three animal groups. In conclusion, our results support an important role for Akt/PKB in the regulation of myocardial contractility and mechanoenergetics.

Clustering of insulin resistance with vascular dysfunction and low-grade inflammation in type 2 diabetes

Vascular dysfunction, low-grade inflammation, insulin resistance, and impaired fibrinolysis have each been reported to be present in type 2 diabetes, but their relationships, and the role of obesity, have not been investigated. We measured insulin sensitivity (euglycemic clamp), forearm blood flow responses to graded local acetylcholine (Ach) and sodium nitroprusside (SNP) infusions, plasma concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, von Willebrand factor (vWF), plasminogen activator inhibitor (PAI)-1, tissue plasminogen activator (tPA), and high-sensitivity C-reactive protein (hs-CRP) in 81 diabetic patients. When patients were stratified by insulin resistance, more severe insulin resistance was associated (P < 0.05) with overweight, central fat distribution, hypertension, and dyslipidemia (with similar sex distribution, age, fasting plasma glucose, and HbA1c). With regard to vascular function, both endothelium-dependent (Ach) (-22, -40, and -52%; P < 0.0001) and -independent (SNP) (-3, -7, and -27%; P < 0.02) vasodilatation were progressively reduced across insulin resistance tertiles. In multivariate analysis, inflammatory markers (IL-6, hs-CRP, and TNF-alpha) were independently associated with insulin resistance and fasting glycemia, fibrinolytic markers PAI-1 and tPA with insulin resistance and central fat distribution, and vascular indexes (vWF, Ach, and SNP vasodilation) with insulin resistance and obesity or cytokines (TNF-alpha or IL-6). In type 2 diabetes, insulin resistance is associated with vascular dysfunction/damage, impaired fibrinolysis, and low-grade inflammation independently of obesity and poor glycemic control.

Growth hormone- and pressure overload-induced cardiac hypertrophy evoke different responses to ischemia-reperfusion and mechanical stretch

OBJECTIVE

To compare the molecular, histological, and functional characteristics of growth hormone (GH)- and pressure overload-induced cardiac hypertrophy, and their responses to ischemia-reperfusion and mechanical stretch.

DESIGN

Four groups of male Wistar rats were studied: aortic banding (n=24, AB) or sham (n=24, controls) for 10 weeks, and GH treatment (n=24; 3.5mg/kg/day, GH) or placebo (n=24, controls) for 4 weeks. At 13 weeks, the rats were randomly subjected to: (i) assessment of basal left ventricular mRNA expression of sarcoplasmic reticulum calcium-ATPase (SERCA-2), phospholamban (PLB), and Na(+)-Ca(2+) exchanger (NCX) and collagen volume fraction (CVF) (Protocol A, 8 rats in each group); (ii) left ventricular no-flow ischemia with simultaneous evaluation of intracellular Ca(2+) handling and ATP, phosphocreatine (PCr) and inorganic phosphate (Pi) content (Protocol B, 12 rats in each group); or (iii) left ventricular mechanical stretch for 40 min with assessment of tumor necrosis-alpha (TNF-alpha) mRNA (Protocol C, 4 rats in each group). Protocol B and C were carried out in a Langendorff apparatus.

RESULTS

In Protocol A, no difference was found as to myocardial mRNA content of Ca(2+) regulating proteins and CVF in GH animals vs controls. In contrast, in the AB group, myocardial mRNA expression of SERCA-2 and PLB was downregulated while that of NCX and CVF were increased vs. controls (p<0.05). In Protocol B, recovery of left ventricular function was significantly decreased in AB vs GH groups and controls and this was associated with 1.6-fold increase in intracellular Ca(2+) overload during reperfusion (p<0.05). Baseline ATP content was similar in the four study groups, whereas PCr and Pi was lower in AB vs GH rats and controls. However, the time courses of high-energy phosphate metabolic changes did not differ during ischemia and reperfusion in the four study groups. In Protocol C, no detectable TNF-alpha mRNA level was found in the left ventricular myocardium of GH treated rats and controls at baseline, while a modest expression was noted in AB animals. Mechanical stretch resulted in de novo myocardial TNF-alpha mRNA expression in GH group and controls, which was dramatically increased in AB animals ( approximately 5-fold above baseline, p<0.001).

CONCLUSIONS

The data show that cardiac hypertrophy activated by short-term GH treatment confers cardioprotection compared with pressure overload with regard to molecular and histological characteristics, and responses to ischemia-reperfusion and mechanical stretch.

Effects of biventricular pacing on interstitial remodelling, tumor necrosis factor-α expression, and apoptotic death in failing human myocardium

AIMS

Recent data from the COMPANION trial have documented that cardiac resynchronization therapy (CRT) with biventricular (BiV) pacing reduces mortality and hospitalization in patients with advanced CHF, but little is known regarding the cellular and molecular mechanisms of CRT. Our aim is to evaluate interstitial remodelling, tumor necrosis factor-alpha (TNF-alpha) expression, and apoptosis in patients with advanced CHF treated with CRT.

METHODS AND RESULTS

We performed endomyocardial biopsies in 10 patients, aged 62, with dilated cardiomyopathy before and 6 months after the implantation of a BiV pacing device. Clinical status and left ventricular (LV) architecture and function were assessed as well as myocardial histology, TNF-alpha expression, and apoptotic index. CRT improved clinical status, as shown by a significant reduction of the Minnesota living with heart failure questionnaire (MLHFQ) score (from 53 to 40) and 6-min walked distance (from 290 to 330 m) (all P<0.05 vs. baseline). This was associated with reverse LV remodelling substantiated by significant reductions of LV volumes and end-systolic circumferential wall stress. Examination of myocardial tissue revealed a significant decrease of collagen volume fraction (CVF) (from 25.16 to 18.0%), TNF-alpha expression (from 9.5 to 3.6 pixel x 10(3)), and apoptotic index (from 2030 to 1408 apoptotic nuclei/10(6)), with increased capillary density (from 1801 to 2011 capillary/mm(2)) after 6 months of CRT (all P<0.05 vs. baseline). Moreover, changes in TNF-alpha expression were positively correlated with both CVF and end-systolic circumferential wall stress (r=0.80 and 0.70, respectively).

CONCLUSION

We provide the first evidence that CRT reduces interstitial remodelling, TNF-alpha expression, and apoptosis. The data may explain the beneficial effects of CRT on CHF progression and survival.

[The role of aldosterone in the development of postinfarction fibrosis]

Aldosterone was discovered in 1953, and until the beginning of the 1960s, when spironolactone was developed, it was the focus of considerable interest among the scientific community. The following 30 years represented a sort of Dark Age, interrupted by the Weber's classic studies. He first demonstrated the pivotal role of aldosterone in the promotion of cardiac hypertrophy and fibrosis and such an observation represented a solid background for the implementation of large survival trials, the RALES and the EPHESUS. These landmark studies showed that aldosterone receptor blockade prolongs survival in advanced and postinfarction heart failure, respectively. After a myocardial infarction, there is a significant upregulation of the local steroidogenic system in the area remote from the scar, that leads to a remarkable fibroblast activation, collagen deposition, and reactive fibrosis. Fibrosis in turn further impairs systolic and diastolic function, and induces electrical heterogeneity with attendant ominous arrhythmias. The following review will dwell upon the importance of fibrosis in postinfarction heart failure, the role of aldosterone, and the novel therapeutic approach based on mineralocorticoid receptor blockade.

Red wine consumption improves insulin resistance but not endothelial function in type 2 diabetic patients

Epidemiological studies have shown that red wine consumption is associated with less cardiovascular mortality in the general population and in the diabetic patients. To determine whether red wine improves insulin resistance in diabetic patients and to explore the relation between insulin sensitivity and endothelial function, we studied vascular reactivity and insulin-mediated glucose uptake in 9 type 2 diabetic patients before and after 2 weeks of red wine consumption (360 mL/d, wine-treated diabetics) and 8 type 2 diabetic patients who did not consume wine (control diabetics). Vascular reactivity was evaluated by plethysmography during intraarterial infusion of acetylcholine (Ach), sodium nitroprusside, and L-N-monomethylarginine. Forearm nitrite balance was measured during Ach infusion. Insulin sensitivity was measured by euglycemic hyperinsulinemic clamp at 1 mU/kg per minute. The basal forearm blood flow and the response to Ach, to sodium nitroprusside, and to L-N -monomethylarginine were unchanged both in the wine-treated and in the control diabetics. In contrast, insulin-mediated whole body glucose disposal improved by 43% after red wine consumption (from 2.79 +/- 0.4 to 4.02 +/- 0.5 mg/kg of lean body mass per minute, P = .02), but did not change in the control group. In conclusion, red wine consumption for 2 weeks markedly attenuates insulin-resistance in type 2 diabetic patients, without affecting vascular reactivity and nitric oxide production.

Food and red wine do not exert acute effects on vascular reactivity

Experimental hyperglycemia and hyperinsulinemia have been shown to affect vascular reactivity. Chronic red wine consumption is associated with less cardiovascular mortality. Whether ingestion of a natural meal and red wine causes acute changes in vascular homeostasis is poorly understood. The aim of the current study was to clarify whether meal ingestion, with and without red wine, exert acute effects on vascular reactivity in healthy humans. We studied vascular reactivity and forearm nitrite balance in 10 healthy subjects under 3 different circumstances: (1) fasting; (2) after ingestion of a standard natural meal (1,050 kcal); and (3) after the same meal enriched with a glass of red wine. We measured forearm blood flow (FBF) by strain-gauge plethismography during intrabrachial, graded infusion of acetylcholine (ACh), sodium nitroprusside (NP), and norepinephrine (NE). We also measured the forearm balance of nitrite before and during ACh infusion. Despite significant increases in plasma glucose and insulin concentrations, the vasodilatory response to Ach and NP after meal ingestion was not different from the fasting response. Similarly, the vasoconstrictory response to NE was similar postprandially and during fasting. Addition of red wine did not modify the response to any of the vasoactive agents. Finally, the forearm nitrite production during Ach infusion was not different in the 3 experimental settings. Food intake, whether associated or not with red wine, does not affect vascular reactivity in normal human subjects.

Growth hormone, acromegaly, and heart failure: an intricate triangulation

Short-term GH or IGF-I excess provides a model of physiological cardiac growth associated with functional advantage. The physiological nature of cardiac growth is accounted for by the following: (i) the increment in cardiomyocyte size occurs prevalently at expense of the short axis. This is the basis for the concentric pattern of left ventricular (LV) hypertrophy, with consequent fall in LV wall stress and functional improvement; (ii) cardiomyocyte growth is associated with improved contractility and relaxation, and a favourable energetic setting; (iii) the capillary density of the myocardial tissue is not affected; (iv) there is a balanced growth of cardiomyocytes and nonmyocyte elements, which accounts for the lack of interstitial fibrosis; (v) myocardial energetics and mechanics are not perturbed; and (vi) the growth response is not associated with the gene re-programming that characterizes pathologic cardiac hypertrophy and heart failure. Overall, the mechanisms activated by GH or IGF-I appear to be entirely different from those of chronic heart failure. Not to be neglected is also the fact that GH, through its nitric oxide (NO)-releasing action, contributes to the maintenance of normal vascular reactivity and peripheral vascular resistance. This particular kind of interaction of GH with the cardiovascular system accounts for: (i) the lack of cardiac impairment in short-term acromegaly; (ii) the beneficial effects of GH and IGF-I in various models of heart failure; (iii) the protective effect of GH and IGF-I against post-infarction ventricular remodelling; (iv) the reversal of endothelial dysfunction in patients with heart failure treated with GH; and (v) the cardiac abnormalities associated with GH deficiency and their correction after GH therapy. If it is clear that GH and IGF-I exert favourable effects on the heart in the short term, it is equally undeniable that GH excess with time causes pathologic cardiac hypertrophy and, if it is not corrected, eventually leads to cardiac failure. Why then, at one point in time in the natural history of acromegaly, does physiological cardiac growth become maladaptive and translate into heart failure? Before this transition takes places, the acromegalic heart shares very few features with other models of chronic heart failure. None of the mechanisms involved in the progression of heart failure is clearly operative in acromegaly, save for the presence of insulin-resistance and mild alterations of lipoproteins and clot factors. Is this enough to account for the development of heart failure? Probably not. On the other hand, it must be stressed that GH and IGF-I activate several mechanisms that play a protective role against the development of heart failure. These include ventricular unloading, deactivation of neurohormonal components, antiapoptotic effect and enhanced vascular reactivity. Ultimately, all data available concur to hypothesize that acromegalic cardiomyopathy represents a progressive model of cardiac hypertrophy in which the cardiotoxic and pro-remodelling effect is intrinsic to the excessive and unrestrained myocardial growth.

Growth hormone prolongs survival in experimental postinfarction heart failure

OBJECTIVES

We evaluated the effects of growth hormone (GH) on survival in experimental heart failure (HF).

BACKGROUND

Growth hormone has been beneficial in various models of experimental HF. Whether GH also affects HF progression and survival is not known.

METHODS

A total of 119 rats with moderate myocardial infarction were randomized to receive either GH (3.5 mg/kg every other day) or placebo for 28 days. Treatment was initiated one month after coronary ligation; the follow-up lasted 13 months. In the surviving animals, Doppler echocardiography and closed-chest Millar left ventricular (LV) catheterization were performed. Apoptosis, collagen volume fraction, and capillary density in the LV zone remote from infarction were measured. The early effects of GH on apoptosis were also assessed in a subgroup of eight infarcted rats, treated as specified earlier and euthanized at one month.

RESULTS

Survival rate was 68% in GH-treated rats and 48% in the placebo group (p = 0.0377). Growth hormone had no effect on myocardial architecture, systolic function, and sarcoplasmatic reticulum calcium ATPase-2 messenger ribonucleic acid. Growth hormone improved LV relaxation; this was associated with a 50% reduction in collagen volume fraction and a 27% increase in capillary density. Growth hormone reduced the apoptotic index by 50% at one month and by 33% at 13 months.

CONCLUSIONS

Growth hormone prolonged survival of rats with postinfarction HF. This effect was associated with marked attenuation of cardiomyocyte apoptosis and pathologic interstitial remodeling in the surviving myocardium and enhanced LV relaxation.

Acute effects of growth hormone on vascular function in human subjects

GH is involved in the long-term regulation of peripheral vascular resistance and vascular reactivity. We determined whether GH plays a role in the acute regulation of vascular function in humans. The acute vascular effects of GH were studied in eight healthy subjects according to a double-blind, placebo-controlled design. Forearm blood flow (FBF), vascular resistance, and nitric oxide (NO) production were monitored during a 4-h infusion of GH into the brachial artery at a rate chosen to raise local GH to stress levels (approximately 40 ng/ml). During GH infusion, FBF rose 75% (P < 0.05), whereas forearm vascular resistance decreased comparably (P < 0.05). These changes were paralleled by augmented forearm release of NO (P < 0.02). GH heightened the response of FBF to the endothelium-dependent vasodilator acetylcholine (Ach; P < 0.02). With the highest Ach dose, FBF reached 30.4 +/- 4.2 and 16.9 +/- 3.1 ml/dl x min in the GH and placebo studies, respectively (P < 0.005). The slopes of the dose-response curves also differed markedly (0.45 +/- 0.07 and 0.25 +/- 0.05 ml/dl x min/ microg in the GH and placebo studies, respectively; P < 0.01). GH caused an upward shift of the FBF response to the endothelium-independent vasodilator sodium nitroprusside (P < 0.01), but did not affect the slope of the dose-response curve. GH infusion did not cause any appreciable increment in the venous IGF-I concentration in the test arm. In conclusion, GH acutely lowers peripheral vascular resistance and stimulates endothelial function. These effects are mediated by activation of the NO pathway and appear to be independent of IGF-I.

Aldosterone receptor blockade improves left ventricular remodeling and increases ventricular fibrillation threshold in experimental heart failure

OBJECTIVES

To investigate the effects of aldosterone receptor blockade in postinfarction heart failure.

METHODS

Eighty-seven rats with moderate myocardial infarction were randomized to receive either no drug or canrenone, the active metabolite of spironolactone, 20 mg/kg/day, or ramipril, 1 mg/kg/day, or a combination of the two drugs. Treatment was initiated 1 month after coronary ligation and lasted 4 weeks. Echocardiography was performed at baseline and after 4 weeks. LV catheterization, isolated heart studies, morphometric histology, myocardial norepinephrine and SERCA-2 mRNA were assessed at the end of the treatment period.

RESULTS

Infarct sizes were 33+/-3, 32+/-3, 34+/-3, and 34+/-4% in the placebo, canrenone, ramipril, and combination groups, respectively. Canrenone attenuated LV remodeling, improved LV systolic and diastolic function, and markedly reduced interstitial and perivascular fibrosis. These effects were increased by concomitant ramipril therapy. Moreover, myocardial norepinephrine content was decreased while ventricular fibrillation threshold significantly augmented by canrenone. SERCA-2 levels remained unchanged.

CONCLUSIONS

Canrenone attenuated LV dilation and interstitial remodeling, and improved LV filling dynamics and systolic function in the rat model of postinfarction heart failure. Addition of ramipril conferred further cardioprotection. Canrenone also reduced myocardial norepinephrine content and increased ventricular fibrillation threshold. The data provide a potential explanation for the decreased sudden death observed in the RALES study. The mechanisms of action of aldosterone inhibition are still poorly understood, despite its proven efficacy in heart failure. Rats with postinfarction heart failure were randomized to receive for 1 month either no drug or canrenone, or ramipril, or a combination of canrenone and ramipril. Canrenone treatment was associated with a significant attenuation of LV dilation, better LV diastolic and systolic dynamics, and a marked reduction of reactive fibrosis. These effects were enhanced by concomitant ramipril therapy. Moreover, canrenone increased ventricular fibrillation threshold and reduced myocardial norepinephrine content. The data may explain the reduced mortality demonstrated by the RALES.

A preliminary randomized study of growth hormone administration in Becker and Duchenne muscular dystrophies

AIM

Since growth hormone (GH) has proven beneficial in experimental heart failure, and the natural history of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) is frequently complicated by the development of dilated cardiomyopathy, we administered GH to six patients with DMD and 10 with BMD, with the evidence of cardiac involvement.

METHODS AND RESULTS

Patients were randomized to receive for 3 months either placebo or recombinant human GH, in a double-blind fashion. In GH-treated patients, left ventricular (LV) mass increased by 16% in BMD and by 29% in DMD (both p<0.01), with a significant increase of relative wall thickness (+19%). Systemic blood pressure remained unchanged, while LV end-systolic stress fell significantly by 13% in BMD and by 33% in DMD, with a slight increase of systolic function indexes. No changes were observed related to cardiac arrhythmias and skeletal muscle function in the patient groups during the treatment period, nor any side effects were observed. Brain natriuretic peptide, interleukin-6, and tumor necrosis factor-alpha circulating levels were elevated at baseline. While brain natriuretic peptide decreased by 40%, cytokine levels did not exhibit significant variations during the treatment period.

CONCLUSIONS

The 3-month GH therapy in patients with DMD and BMD induces a hypertrophic response associated with a significant reduction of brain natriuretic peptide plasma levels and a slight improvement of systolic function, no changes in skeletal muscle function, and no side effects.

Prospective evaluation of hypertensive patients with carotid kinking and coiling: an ultrasonographic 7-year study

The aim of this study was to determine the incidence of vascular events during a 7-year follow-up evaluation in a group of 34 hypertensive patients with kinking of the internal carotid artery and 36 well-matched hypertensive control subjects. The carotid intima-media thickness (IMT) was measured at three points of the carotid bifurcation and at three points of carotid kinking on the ultrasonographic posterior wall. The mean IMT measured in the segment of the angular bending was lower than the mean values detected at the bifurcation in normal subjects and in hypertensives without carotid elongation (p < 0.01). At the carotid bifurcation of the same side of the kinking, there was an arterial IMT that was significantly lower as compared to the contralateral axis and to the measurements obtained in other hypertensive subjects. During a 7-year follow-up study, 10 vascular events occurred in the hypertensives with carotid kinking and 14 in the controls, without significant differences between the 2 groups. In hypertensives with carotid kinking, the mean IMT measured on the angular bending and at the ipsilateral carotid bifurcation was significantly lower than the values obtained at the contralateral bifurcation and in the other hypertensive subjects. In the 7-year follow-up study, moreover, the presence of carotid kinking does not impact the incidence of vascular events in the hypertensive population. Thus, the presence of carotid kinking in hypertensive subjects may not be considered a further risk factor for ischemic events.

Islet transplantation under the kidney capsule corrects the defects in glycogen metabolism in both liver and muscle of streptozocin-diabetic rats

Insulin-deficient rats are characterized by multiple defects in the pathway of glycogen synthesis and breakdown in both liver and skeletal muscle. The aim of this study was to clarify whether islet transplantation under the kidney capsule, which is associated with delivery of insulin into the peripheral circulation, is able to normalize glycogen metabolism in liver and muscle of streptozotocin-diabetic rats. Three groups of male Lewis rats were studied under fasting condition: controls, untreated diabetics, and islet transplanted diabetics. Glycogen content, glucose-6-phosphate concentration, and glycogen synthase activity were measured in both liver and skeletal muscle. Untreated diabetic rats were characterized by an increase in glycogen content of 178% and a reduction of glucose-6-phosphate level of 50%. Both glycogen and glucose-6-phosphate contents were restored to normal in transplanted diabetic rats. Active glycogen synthase (0.35 +/- 0.1 nmol/min/mg) and activity ratio (0.22 +/- 0.04) were significantly impaired compared with controls (0.99 +/- 0.2 nmol/min/mg and 0.43 +/- 0.06, respectively) and were normalized by islet transplantation. In the skeletal muscle, glycogen content was similar in the three groups of animals, whereas muscle glucose-6-phosphate level was reduced by 28% and glycogen synthase was in a less active state in the untreated diabetic rats. Both the glucose-6-phosphate concentration and the kinetic profile of glycogen synthase were normalized by islet transplantation. In conclusion, islet transplantation under the kidney capsule corrects the diabetes-induced abnormalities in glycogen and glucose-6-phosphate content and glycogen synthase activity in both liver and skeletal muscle.

[Placebo in clinical research--a continual compromise between ethical requirements and scientific rigor]

The use of placebo in clinical trials has been the object of continuous controversy. If effective treatment is not available, then the comparison of a new treatment versus placebo is the only sound and ethical approach. If effective treatment exists and its withdrawal can cause severe or irreversible harm or severe suffering, the use of placebo is forbidden. In all other instances, the scientific community has been divided into two extreme positions: the placebo orthodoxy considers the use of placebo as the only scientifically and hence ethically valid approach; and the active-control orthodoxy denies the use of placebo and recommends the comparison between active treatments. The latter has been supported by the Declaration of Helsinki that, until the Edinburgh 2000 Version, denied the use of placebo whenever effective treatment existed. This position has been the object of recent, strong criticism by ethicists and international Institutions, to the point that in October 2001 the World Medical Association decided to review paragraph 29 of the Declaration. The new version of the Declaration admits the use of placebo, even in the presence of effective treatment, when there are scientifically sound methodological reasons or when the patients receiving placebo are not exposed to any additional risk of serious or irreversible harm. The problem now is that the sudden opening of the World Medical Association may be interpreted as an encouragement to use placebo. Thus, it is necessary to define a new area for a scientifically motivated, but not unscrupulous use of placebo.

Carotid atherosclerosis and ischemic stroke in young patients

BACKGROUND

Epidemiological studies indicate a high prevalence of carotid atherosclerosis in elderly patients with ischemic stroke. The aim of this study was to investigate the presence of early carotid atherosclerotic lesions in young subjects with ischemic stroke, in the absence of the common atherosclerotic risk factors.

METHODS

We studied 98 young patients with first ischemic stroke (54 males and 44 females; mean age 41.2 years; range 32-50) and 96 healthy controls. All subjects underwent ultrasonographic scanning of the carotid arteries according to a standardized protocol.

RESULTS

The carotid intima-media thickness was significantly increased in the patient group (p<0.001) compared with controls. In addition, the prevalence of carotid atherosclerotic plaques was greater in the patients than in the controls (p<0.001). In particular, we detected 18 non-occlusive carotid plaques and 16 thrombotic occlusions. In 8 patients, the lesions were bilateral. The echographic pattern of the plaques was hard in 8 cases, soft in 5 cases, and mixed in the remaining 5 cases.

CONCLUSIONS

We detected an increased wall thickness of the carotid arteries and an increased prevalence of carotid atherosclerotic lesions and carotid thrombotic occlusions in young patients with ischemic stroke, with a relative low incidence of cardiovascular risk factors. This finding suggests that arterial intima-media thickness per se is an important determinant of vascular disease in young patients. The data also provide indirect support for the potential role of genetic factors in the genesis of atherosclerosis in young patients.

Effects of canrenone on myocardial reactive fibrosis in a rat model of postinfarction heart failure

BACKGROUND

Spironolactone reduces overall mortality by 30% in advanced congestive heart failure. Nevertheless, few data are available with regard to the effects of mineral corticoid inhibition in postinfarction heart failure.

MATERIALS AND METHODS

Experimental myocardial infarction was induced by left coronary ligation in 70 male rats with body weights ranging from 180 to 200 gr. The day after surgery, animals were randomized to either placebo or canrenone-gamma-cyclodestrin 8 mg/kg/die or canrenone-gamma-cyclodestrin 18 mg/kg/die. Twelve animals served as the control group. After two weeks, the rats underwent closed chest left ventricular catheterization. The heart was the rapidly excised for subsequent histological analysis.

RESULTS

Compared with controls, infarcted rats had reduced left ventricular systolic pressures (-6%) and higher left ventricular end-diastolic pressures (+600%), associated with a marked increase of mean collagen fraction (+446%) and perivascular fibrosis (+72%). Compared with placebo-infarcted rats, in the group treated with high canrenone dose there was a significant reduction of left ventricular systolic and end-diastolic pressures (-6.5% and -23%, respectively) and an attenuation of interstitial and perivascular fibrosis (-47% and -34%, respectively). The low-dose canrenone group did not show differences compared with the placebo infarcted rats, except for a slight reduction of mean collagen fraction (-21%).

CONCLUSIONS

Canrenone attenuates LV interstitial remodeling and reduces filling pressures in rats with postinfarction heart failure.

Supraphysiological doses of GH induce rapid changes in cardiac morphology and function

GH is an agent widely used in sport to improve physical performance and has been proposed as adjunctive therapy in several clinical conditions. However, its short-term effects on the normal human heart are poorly understood. Sixty young normal volunteers (30 males and 30 females) were enrolled in a multicenter, double-blind, placebo-controlled study. All subjects were randomized to receive GH (0.03 or 0.06 mg/kg.d) or placebo. A complete Doppler-echocardiographic examination was performed at baseline and after 4 wk of treatment. Low-dose GH did not significantly affect echocardiographic parameters. In contrast, high-dose GH increased left ventricular mass index by 12% (P < 0.05). The type of growth response was concentric, because left ventricular wall thickness but not diameter increased, leading to a 10% increase of relative wall thickness. These structural changes were associated with functional changes, including a significant increase in cardiac index and a decrease in peripheral vascular resistance; diastolic function was not altered. Fractional shortening and systemic blood pressure were unchanged in the two treatment groups. In conclusion, administration of GH for 4 wk at doses that simulate GH abuse in sport caused a high cardiac output state associated with concentric left ventricular remodeling.

Differential expression of TNF-alpha, IL-6, and IGF-1 by graded mechanical stress in normal rat myocardium

An isovolumic normal rat heart Langendorff model was used to examine the effects of moderate (15 mmHg) and severe (35 mmHg) mechanical stretch on the time course (from 0 to 60 min) of myocardial expression of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and insulin-like growth factor (IGF)-1 and their cognate receptors. After 10 min of moderate stretch, TNF-alpha was de novo expressed, whereas constitutive IL-6 and IGF-1 levels were slightly upregulated; no further changes occurred up to 60 min. In comparison, severe stretch resulted in a higher and progressive increase in TNF-alpha, IL-6, and IGF-1 expression up to 20 min. After 20 min, whereas TNF-alpha expression further increased, IL-6 and IGF-1 levels progressively reduced to values lower than those observed under moderate stretch and in unstretched (5 mmHg) control myocardium (IL-6). Mechanical stretch did not significantly alter the expression of the cognate receptors. Indeed, the TNF-alpha receptor (p55) tended to be progressively upregulated under severe stretch over time. The current data provide the first demonstration that TNF-alpha, IL-6, and IGF-1 ligand-receptor systems are differentially expressed within the normal rat myocardium in response to graded mechanical stretch. Such findings may have potential implications with regard to compensatory hypertrophy and failure.

Growth hormone corrects vascular dysfunction in patients with chronic heart failure

OBJECTIVES

The goal of this study was to test the hypothesis that growth hormone (GH) administration to patients with chronic heart failure (CHF) corrects their vascular dysfunction.

BACKGROUND

Endothelial dysfunction is a prominent feature of CHF. Recent evidence indicates that GH plays a role in vascular reactivity.

METHODS

We studied vascular reactivity in 16 patients with CHF (New York Heart Association class II to III) before and after three months of GH (4 IU subcutaneously every other day) or placebo administration in a randomized, double-blind trial. We measured forearm blood flow (FBF) by strain-gauge plethysmography during intrabrachial, graded infusion of acetylcholine (ACh) and sodium nitroprusside (NP). We also measured the forearm balance of nitrite and cyclic guanosine monophosphate (cGMP) before and during ACh infusion. Maximal oxygen uptake (VO2max) was measured by breath-to-breath respiratory gas analysis.

RESULTS

Before treatment, the response of FBF to ACh was flat (p = NS). Growth hormone, but not placebo, greatly improved this response (p = 0.03) and, concomitantly, increased the forearm release of nitrite and cGMP (p < 0.05). Growth hormone also potentiated the FBF response to NP (p = 0.013). Growth hormone interacted with ACh response (p = 0.01) but not with the response to NP (p = NS). Accordingly, GH enhanced the slope of the dose-response curve to ACh (p < 0.05) but not to NP. The VO2max increased significantly after GH treatment (20 +/- 2 and 26 +/- 2 ml x Kg(-1) x min(-1) before and after GH treatment, respectively, p < 0.05) but not after placebo.

CONCLUSIONS

A three-month treatment with GH corrected endothelial dysfunction and improved non-endothelium-dependent vasodilation in patients with CHF. The data highlight the potential role of GH in the progression of congestive heart failure.