Chronic beta2-adrenergic receptor stimulation increases proliferation of human cardiac fibroblasts via an autocrine mechanism

OBJECTIVE: The aim of this study was to determine whether chronic beta-adrenergic receptor (beta-AR) stimulation induces proliferation of human cardiac fibroblasts and to investigate the mechanism(s) involved. METHODS AND RESULTS: In vitro cultures of human cardiac fibroblasts were established from biopsies of right atrial appendage. RT-PCR analysis and pharmacological studies demonstrated that these cells express predominantly the beta(2)-AR subtype coupled to activation of adenylyl cyclase and p44/42 mitogen-activated protein kinase (MAPK). Proliferation was determined by cell counting over a 6-day period in medium containing 2.5% fetal calf serum (control) or supplemented with the non-selective beta-AR agonist isoproterenol (ISO). ISO induced a concentration-dependent increase in cardiac fibroblast proliferation, which was maximal at 1 micromol/l. This increased proliferation was inhibited by the beta(2)-AR-selective antagonist ICI-118,551, but not the beta(1)-AR-selective antagonist atenolol. Direct activation of adenylyl cyclase alone (0.1-10 micromol/l forskolin) stimulated cyclic AMP production and MAPK activation, but did not induce cell proliferation. Since catecholamines are not considered to be 'classical' growth factors, we subsequently investigated whether beta(2)-AR stimulation results in secretion of growth factors that are able to stimulate proliferation in an autocrine manner. Conditioned medium obtained from cardiac fibroblasts treated with ISO for 48 h increased proliferation of parallel cultures of fibroblasts in the presence of the beta-AR antagonist alprenolol. Heat-treatment of this conditioned medium fully prevented the increase in cell proliferation, indicating that the autocrine factor(s) are heat-sensitive proteins. CONCLUSIONS: Chronic beta(2)-AR stimulation increases proliferation of human cardiac fibroblasts via a mechanism involving increased secretion of heat-sensitive growth factors.     

HLA-B27 and genetic predisposing factors in spondyloarthropathies

With the mapping of the human genome having been completed, our ability to investigate and ideally better understand the genetic basis of rheumatic diseases is advancing at a rapid pace. Substantial evidence strongly favors a direct role for HLA-B27 in genetic susceptibility to ankylosing spondylitis and related spondyloarthropathies, although the underlying molecular basis has yet to be identified. HLA-B27 contributes only 16 to 50% of the total genetic risk for the disease, clearly indicating that other genes must be involved. However, no other putative disease genes have yet been absolutely proven. Potential genes include MHC (HLA class II, low molecular weight proteasome [LMP], transporter associated with antigen processing (TAP), tumor necrosis factor [TNF]-alpha, and major histocompatibility complex class I chain-related gene A (MICA), as well as non-MHC genes (IL-1RA, IL-6, IL-10, and CYP2D6). Genome-wide screens have identified other chromosomal areas of interest: 1p, 2q, 6p, 9q, 10q, 16q, and 19q. However, different studies have given conflicting results. HLA-B27 itself is a serologic specificity, which encompasses 25 different alleles that encode 23 different products (proteins): HLA-B*2701 to B*2723. These alleles may have evolved from the most widespread subtype, B*2705, and two of them, B*2706 in Southeast Asia and B*2709 in Sardinia, seem not to be associated with ankylosing spondylitis. The distinction between the disease associated and nonassociated subtypes may provide clues to the actual role of B27 in disease pathogenesis.     

Arterial pressure lowering effect of chronic atenolol therapy in hypertension and vasoconstrictor sympathetic drive

Although the beta1-adrenergic blocking agent atenolol is an established antihypertensive therapy, its effect on peripheral sympathetic vasoconstrictor drive has remained controversial. In patients with hypertension, atenolol therapy has been reported to either increase or have no effect on peripheral vascular resistance, despite other reports showing no change or a decrease in peripheral sympathetic drive. This study was designed, in patients with untreated essential hypertension (EHT), to quantify changes in simultaneously measured peroneal muscle sympathetic nerve activity (MSNA) and calf vascular resistance (CVR) accompanying atenolol therapy. MSNA was quantified as the mean frequency of single units (s-MSNA) and as multiunit bursts (MSNA bursts) using the technique of microneurography, and CVR was measured using a standard plethysmographic technique. Firstly, by comparing two age- and body weight- matched groups, each of 14 patients with hypertension, we found that the group on atenolol therapy (treated-HT) had similar MSNA values counted over the same number of cardiac beats and similar CVR levels (at least P>0.40) to the group without therapy (untreated-HT). Secondly, we examined 10 EHT patients before and after 8+/-0.4 weeks of oral atenolol therapy (HT-A) in comparison to seven control patients with hypertension and no treatment (HT-C) who were examined over a similar period of time. We found that the measures of MSNA and CVR did not significantly change in both groups. We conclude that the arterial pressure lowering effect of atenolol was not related to significant changes in central vasoconstrictor sympathetic drive to the periphery.     

Fenofibrate enhances urate reduction in men treated with allopurinol for hyperuricaemia and gout

OBJECTIVE: To assess the short-term urate-lowering effect of fenofibrate in men on long-term allopurinol therapy for hyperuricaemia and gout. METHODS: Ten male patients (38-74 yr) with a history of chronic tophaceous or recurrent acute gout with hyperuricaemia and on established allopurinol at 300-900 mg/day for > or =3 months were studied in an open-crossover study of fenofibrate therapy. Allopurinol at the established dose was continued throughout the study. Clinical and biochemical assessments (serum urate and creatinine, 24-h urinary excretion of urate and creatinine, liver function tests, creatine kinase and fasting serum lipids) were undertaken at: (i) baseline, (ii) after 3 weeks of once-daily therapy with micronized fenofibrate (Lipantil Micro) at 200 mg and (iii) 3 weeks after fenofibrate was withdrawn. RESULTS: Fenofibrate was associated with a 19% reduction in serum urate after 3 weeks of treatment (mean+/-S.E. 0.37+/-0.04 vs 0.30+/-0.02 mM/l; P=0.004). The effect was reversed after a 3-week fenofibrate withdrawal period (0.30+/-0.02 vs 0.38+/-0.03 mM/l). There was a rise in uric acid clearance with fenofibrate treatment of 36% (7.2+/-0.9 vs 11.4+/-1.6 ml/min, normal range 6-11; P=0.006) without a significant change in creatinine clearance. Both total cholesterol and serum triglycerides were also reduced. No patient developed acute gout whilst taking fenofibrate. CONCLUSIONS: Fenofibrate has a rapid and reversible urate-lowering effect in patients with hyperuricaemia and gout on established allopurinol prophylaxis. Fenofibrate may be a potential new treatment for hyperuricaemia and the prevention of gout, particularly in patients with coexisting hyperlipidaemia or those resistant to conventional therapy for hyperuricaemia.     

Current and Practical Management of Acute Myocardial Infarction

Journal of Thrombosis and Thrombolysis -     

The effects of losartan compared to atenolol on stroke in patients with isolated systolic hypertension and left ventricular hypertrophy. The LIFE study

The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study reported that a losartan-based antihypertensive regimen reduced cardiovascular morbidity and mortality (composite of cardiovascular death, stroke, and myocardial infarction) more than therapy based on atenolol in patients with left ventricular hypertrophy and isolated systolic hypertension (ISH). Patients aged 55-80 years with blood pressures 160-200/<90 mm Hg were followed for a mean of 4.7 years. Blood pressure was similarly reduced in the losartan (n=660) and atenolol (n=666) ISH groups. There were 88 (6.6%) patients who experienced a stroke, 18 of which were fatal. Of patients experiencing strokes, 72.7% had an ischemic stroke. ISH patients in LIFE compared to the non-ISH group had a higher incidence of any stroke and embolic stroke, and similar incidences of fatal, atherosclerotic, and hemorrhagic/other strokes. The incidence of any stroke (40% risk reduction [RR], p=0.02), fatal stroke (70% RR, p=0.035), and atherothrombotic stroke (45% RR, p=0.022) was significantly lower in losartan-treated compared to the atenolol-treated patients. The 36% RR for embolic strokes in the losartan group was not statistically significantly (p=0.33) different from the atenolol group. These data suggest that losartan-based treatment is more effective than an atenolol-based treatment for patients with ISH and a high risk for stroke.     

Ovarian recovery after stem cell transplantation

Autologous or allogeneic SCT with conventional conditioning (chemotherapy with or without irradiation) has emerged as an effective and potentially curative therapy in patients with hematologic malignancies and in other selected solid tumors; however, several patients experience significant early and delayed side effects, including long-term endocrine imbalance and infertility. In spite of several reproductive recovery and pregnancy reports published in the oncology literature, review of medical literature reveals a paucity of comparable information in the SCT field. We report here four cases of ovarian recovery in patients who received hormonal replacement therapy after diagnosis of primary ovarian failure due to high-dose chemotherapy and SCT.     

Intravenous busulfan in children prior to stem cell transplantation: study of pharmacokinetics in association with early clinical outcome and toxicity

We studied the pharmacokinetics of intravenous busulfan (Bu) in children in order to further optimize intravenous Bu dosing in relation to toxicity and survival. A total of 31 children undergoing Bu-based conditioning for allogeneic SCT were enrolled in a study. The starting dose was 1.0 mg/kg (age < 4 years) and 0.8 mg/kg (age > or =4 years), four doses per day during 4 days. Dose adjustment was allowed up to a maximum dose of 1.0 mg/kg per dose if the target area under the serum concentration-time curve (AUC) was not reached. Pharmacokinetic studies were performed after the first dose. Donor engraftment was established in 28 out of 31 patients. The average AUC after the first dose was the same in children < 4 years as in children > or =4 years. Mean clearance was higher in children < 4 years than in children > or =4 years. In 35% of all patients, total AUC was within the target AUC. The other children's AUCs were below the target range. No relationships were found between systemic exposure to Bu and toxicity or clinical outcome. We concluded that, in accordance with previous data, within the observed AUCs no clear relationship was observed between Bu AUC and outcome with respect to toxicity, engraftment and relapse.     

Primary pulmonary botryomycosis. A manifestation of chronic granulomatous disease.

A 19-year-old woman with a childhood history of cavitating left upper lobe pneumonia presented with persistent weight loss, fever, cough and roentgenographic evidence of right upper lobe pneumonia resistant to antibiotic therapy. An open lung biopsy led to the diagnosis of botryomycosis. Neutrophil function studies including flow cytometric evaluation of oxidative burst, bacterial killing and evaluation of neutrophil cytosolic proteins required for oxidase activation were consistent with chronic granulomatous disease. This is the first case report of primary pulmonary botryomycosis as a clinical manifestation of CGD. Other recent cases of immunodeficiency states associated with botryomycosis are reviewed.