Antipeptide antibodies for detecting crab (Callinectes sapidus) molt-inhibiting hormone

In crustaceans, the synthesis of ecdysteroid molting hormones is regulated by molt-inhibiting hormone (MIH), a neuropeptide produced by an eyestalk neuroendocrine system, the X-organ/sinus gland complex. Using sequence analysis software, two regions of the blue crab (Callinectes sapidus) MIH peptide were selected for antibody production. Two 14-mer peptides were commercially synthesized and used to generate polyclonal antisera. Western blot analysis revealed that each antiserum bound to proteins of the predicted size in extracts of C. sapidus sinus glands, and lysates of insect cells containing recombinant MIH. Thin section immunocytochemistry using either antiserum showed specific immunoreactivity in X-organ neurosecretory cell bodies, their associated axons and collaterals, and their axon terminals in the sinus gland.

Amlodipine: effective for treatment of mild to moderate essential hypertension and left ventricular hypertrophy

This was a 20-week, open-label, uncontrolled clinical investigation of the long-acting calcium antagonist amlodipine in 33 male or female patients with essential hypertension and left ventricular hypertrophy (LVH). A once-daily dose (5-10 mg/day) of amlodipine provided a consistent antihypertensive effect, reducing the sitting diastolic (-13.8% change) and systolic (-13.0% change) blood pressures by clinically meaningful and statistically significant (p = 0.0001, n = 33) amounts. Amlodipine had no effect on heart rate. A significant regression in LVH was seen (left ventricular mass index reduced from 169.0 [SD 30.7] g/m(2) to 140.6 [SD 19.6] g/m(2), p < 0.01, n = 12). There was also a significant reduction in total peripheral resistance and improvement in left ventricular diastolic filling (E/A ratio increased from 0.86 pre-treatment to 1.03 post-treatment, p = 0.038, n = 12). These results are consistent with other studies in showing that a relatively short treatment regimen with amlodipine is associated with a significant reduction in left ventricular mass index.

Expression of crustacean (Callinectes sapidus) molt-inhibiting hormone in insect cells using recombinant baculovirus

Molt-inhibiting hormone (MIH) negatively regulates the synthesis of ecdysteroid molting hormones by crustacean Y-organs. We report here the expression of blue crab (Callinectes sapidus) MIH in insect cells using recombinant baculovirus. Insect Sf9 cells were transfected with recombinant baculovirus containing a DNA insert encoding the C. sapidus MIH prohormone (signal sequence plus mature hormone). The construct was designed to yield a mature, fully processed recombinant MIH (recMIH). Several baculovirus recombinants showing no contamination with wild-type viral DNA were subsequently analyzed for their ability to direct expression of recMIH. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins from infected cells revealed time-dependent expression of two proteins of approximately the predicted size for the C. sapidus MIH prohormone and mature hormone. Western blot results (using antiserum against MIH of Carcinus maenas) indicated that the proteins were MIH-immunoreactive. N-Terminal amino acid sequence data and mass spectral analysis indicated the expressed proteins were of the correct sequence and molecular mass. Cell lysates containing the recombinant protein dose-dependently suppressed the synthesis of ecdysteroids by Y-organs in vitro. We anticipate the recombinant peptide will prove useful for studies of the structure and function of MIH.

Effects of acute exercise on hemorheological, endothelial, and platelet markers in patients with chronic heart failure in sinus rhythm

BACKGROUND

Chronic heart failure (CHF) is associated with an increased risk of thrombosis and thromboembolic events, including stroke and venous thromboembolism. which may be related to a prothrombotic or hypercoagulable state. Acute vigorous exercise has been associated with activation of hemostasis, and this risk may well be particularly increased in patients with CHF.

HYPOTHESIS

The study was undertaken to determine whether acute exercise would adversely affect abnormalities of hemorheological (fibrinogen, plasma viscosity, hematocrit), endothelial (von Willebrand factor), and platelet markers (soluble P selectin) in patients with CHF.

METHODS

We studied 22 ambulant outpatients (17 men; mean age 65+/-9 years) with stable CHF (New York Heart Association class II-III and a left ventricular ejection fraction of < or =40%) who were exercised to exhaustion on a treadmill. Results were compared with 20 hospital controls (patients with vascular disease, but free of CHF) and 20 healthy controls.

RESULTS

Baseline von Willebrand factor (p = 0.01) and soluble P-selectin (p = 0.006) levels were significantly elevated in patients with CHF when compared with controls. In the patients with CHF who were exercised, plasma viscosity, fibrinogen, and hematocrit levels increased significantly, both immediately post exercise and at 20 min into the recovery period (repeated measures analysis of variance, all p<0.05). There was a positive correlation between exercise workload and the maximal changes in plasma viscosity in the patients with CHF (Spearman r = 0.5, p = 0.02). Plasma viscosity levels increased with exercise in the hospital control group, although no other exercise-induced changes were noted in this group.

CONCLUSION

The present study indicates that the hemorheological indices. fibrinogen, and hematocrit specifically increase during acute exercise in patients with CHF. Although moderate exercise should be encouraged in patients with CHF, vigorous exercise should probably be avoided in view of its potential prothrombotic effects in this high-risk group of patients.

Molt-inhibiting hormone immunoreactive neurons in the eyestalk neuroendocrine system of the blue crab, Callinectes sapidus

The production of ecdysteroid molting hormones by crustacean Y-organs is negatively regulated by a neuropeptide, molt-inhibiting hormone. It is generally agreed that molt-inhibiting hormone is produced and released by the eyestalk neuroendocrine system. In the present study, immunocytochemical methods were used to detect molt-inhibiting hormone immunoreactive neurons in eyestalk ganglia of the blue crab, Callinectes sapidus. The primary antiserum used was generated against molt-inhibiting hormone of the green shore crab, Carcinus maenas. A preliminary Western blot analysis indicated the antiserum binds molt-inhibiting hormone of Callinectes sapidus. Using confocal and conventional immunofluorescence microscopy, molt-inhibiting hormone immunoreactivity was visualized in whole mounts and thin sections of Callinectes sapidus eyestalk ganglia. Immunoreactivity was detected in 15-25 neurosecretory cell bodies in the medulla terminalis X-organ, their associated axons and collateral branches, and their axon terminals in the neurohemal sinus gland. The cellular organization of molt-inhibiting hormone immunoreactive neurons in blue crabs is generally similar to that reported for other crab species. The combined results suggest the cellular structure of the molt-inhibiting hormone neuroendocrine system is highly conserved among brachyurans.

Abnormalities of hemorheological, endothelial, and platelet function in patients with chronic heart failure in sinus rhythm: effects of angiotensin-converting enzyme inhibitor and beta-blocker therapy

BACKGROUND

To investigate the hypothesis that abnormalities of hemorheological (fibrinogen, plasma viscosity), endothelial (von Willebrand factor [vWF]), and platelet (soluble P-selectin) function would exist in patients with chronic heart failure (CHF) who are in sinus rhythm, we conducted a cross-sectional study of 120 patients with stable CHF (median ejection fraction 30%). We also hypothesized that ACE inhibitors and beta-blockers would beneficially affect the measured indices.

METHODS AND RESULTS

In the cross-sectional analysis, plasma viscosity (P=0.001), fibrinogen (P=0.02), vWF (P<0.0001), and soluble P-selectin (P<0.001) levels were elevated in patients with CHF compared with healthy controls. Women demonstrated greater abnormalities of hemorheological indices and vWF than males (all P<0.05). Plasma viscosity (P=0.009) and fibrinogen (P=0.0014) levels were higher in patients with more severe symptoms (New York Heart Association [NYHA] class III-IV), but there was no relationship with left ventricular ejection fraction. When ACE inhibitors were introduced, there was a reduction in fibrinogen (repeated-measures ANOVA, P=0.016) and vWF (P=0.006) levels compared with baseline. There were no significant changes in hemorheological, endothelial, or platelet markers after the introduction of beta-blocker therapy, apart from a rise in mean platelet count (P<0.001).

CONCLUSIONS

Abnormal levels of soluble P-selectin, vWF, and hemorheological indices may contribute to a hypercoagulable state in CHF, especially in female patients and in those with more severe NYHA class. Treatment with ACE inhibitors improved the prothrombotic state in CHF, whereas the addition of beta-blockers did not. These positive effects of ACE inhibitors may offer an explanation for the observed reduction in ischemic events in clinical trials.

Mosquitofish (Gambusia affinis) vitellogenin: identification, purification, and immunoassay

Vitellogenin is a phospholipoglycoprotein precursor of egg yolk. In mature female fish, vitellogenin is synthesized and secreted by the liver in response to circulating estrogens. Vitellogenin is normally undetectable in the blood of male fish, but can be induced by exposure to compounds possessing estrogenic activity. Thus, the presence of vitellogenin in blood of male fish can serve as a useful biomarker for assessing previous exposure to estrogenic compounds. In the present study, we report identification and purification of vitellogenin in the mosquitofish (Gambusia affinis). Anti-vitellogenin immune serum was generated and used to develop an immunoblot assay for detection of vitellogenin. A combination of immunoblotting and densitometric scanning was used to assess the time- and dose-dependent effects of 17alpha-ethynylestradiol on vitellogenesis in male G. affinis. The results indicate that changes in the level of vitellogenin in mosquitofish blood can be reliably detected by the immunoblot assay, and that the mosquitofish may be a useful bioindicator organism for detecting estrogenic contamination of the aquatic environment.

Management of pericardial effusion by drainage: a survey of 10 years' experience in a city centre general hospital serving a multiracial population

The aim of the study was to determine the aetiology of large and symptomatic pericardial effusions and to review the management and subsequent outcome. A survey was done on a consecutive cases of patients who had undergone percutaneous pericardiocentesis over a 10 year period in a city centre general hospital serving a multiethnic catchment population. In all, 46 patients (24 male, 22 female; age range 16 to 90 years, mean 54 years) underwent a total of 51 pericardial drainage procedures (or attempted pericardiocentesis) between 1989 and 1998. Malignancy (44%), tuberculosis (26%), idiopathic (11%), and post-cardiac surgery (9%) were the most common causes of pericardial effusion. The most common presenting symptoms were breathlessness (90%), chest pain (74%), cough (70%), abdominal pain (61%) (presumed to be related to hepatic congestion), and unexplained fever (28%). In the 12 cases of tuberculous pericarditis, nine occurred in patients of Indo-Asian origin, and three in patients of Afro-Caribbean origin. Fever, night sweats, and weight loss were common among these patients, occurring in over 80% of cases of tuberculous pericarditis. Pulsus paradoxus was the most specific sign (100%) for the presence of echocardiographic features of tamponade, with strongest positive predictive value (100%). Although malignancy remains the most common cause in developed countries, tuberculous disease should be considered in patients from areas where tuberculosis is endemic. Percutaneous pericardiocentesis remains an effective measure for the immediate relief of symptoms in patients with cardiac tamponade, although its diagnostic yield in tuberculous pericarditis is relatively low.

A pilot study of streptokinase-induced endothelial injury and platelet activation following acute myocardial infarction

OBJECTIVE

To relate the changes in serum vitamin E, an essential antioxidant, to changes in fibrinogen, as well as indices of endothelial damage [as indicated by plasma markers, soluble thrombomodulin (sTM) and von Willebrand factor (vWf), and an index of platelet activation (soluble P selectin (sPsel)], in myocardial infarction treated with thrombolytic therapy.

DESIGN AND SETTING

Prospective longitudinal pilot study in a teaching hospital Coronary Care Unit.

SUBJECTS AND INTERVENTION

Seventeen patients (12 men: mean age (62 years +/- SD 11 years) admitted with acute myocardial infarction (AMI), who were given thrombolytic therapy, and 59 healthy controls.

RESULTS

Baseline levels of fibrinogen (Mann-Whitney test, P = 0.0055) and vWf (P < 0.001) were significantly higher than controls, but sPsel, sTM or vitamin E levels were not significantly different. Following thrombolysis, as expected, median concentrations of plasma fibrinogen fell profoundly (Friedman ANOVA P < 0.001) so that after 45 min, levels were undetectable in 13 patients. At 24-h median fibrinogen concentration had recovered to approximately 30% of baseline (P < 0.01) and was still undetectable in three patients. Levels of vWf and sPsel increased steadily, reaching significance after three hours (both P < 0.05). However, levels of sTM rose immediately after thrombolysis, peaking between 1 and 3 h, and remained elevated at 24 h. These increases corresponded to a simultaneous early fall in serum vitamin E concentrations.

CONCLUSION

The present pilot study demonstrates significant endothelial damage and platelet activation in association with increased oxidative stress following streptokinase therapy for AMI.

Acquired angioedema associated with sinusitis

Acute and chronic sinusitis are major clinical problems faced by physicians in several disciplines. Although there is a much studied relationship between sinusitis and asthma, as well as a well-known association of sinusitis and Wegener's granulomatosis, there is scant evidence suggesting an association of angioedema with sinusitis. Angioedema can be extremely disfiguring, and is potentially lethal due to compromised airways. It is also a frustrating diagnostic dilemma for patients and physicians. A diagnosis is found in fewer than 25% of chronic urticaria patients and much less for angioedema. In this study, we report the cases of nine patients who were treated for chronic sinusitis, but who were referred for episodes of angioedema. Patients with a known diagnosis, such as the hereditary form, or drug or food allergies, were excluded. Based on clinical suspicion or CT scan results, nine patients were treated for chronic sinusitis. Only three had symptoms suggesting a sinus infection at presentation. After sinusitis treatment, all nine patients had a marked improvement in their angioedema. None had further severe angioedema episodes. Some patients continued to have mild episodes of angioedema, which they related to recurrence of sinusitis symptoms, and which responded to antibiotics. The nine angioedema patients in this series all had strong evidence of sinusitis, albeit, most patients had occult disease identified by CT scan. The dramatic improvement in angioedema with sinusitis treatment corroborates a causal relationship. Such findings encourage the investigation of sinusitis in these otherwise idiopathic patients. Sinusitis evaluation may also be indicated for urticaria.

Management of pulmonary thrombo-embolism using catheter manipulation: a report of four cases and review of the literature

To date the management of pulmonary thrombo-embolism is still largely limited to anticoagulation. Heparin and oral anticoagulation have been shown to be effective in reducing recurrence and death in venous thrombo-embolism. During the acute stage, systemic thrombolytic therapy has also been advocated for the rapid dissolution of the thrombus in patients with haemodynamic instability. We describe four patients with acute pulmonary thrombo-embolism who were managed with catheter-based thrombus manipulation with intrapulmonary thrombolysis. This management strategy should be considered in patients with pulmonary thrombo-embolism who continue to deteriorate despite conventional management with anticoagulation or systemic thrombolysis.

Do Indo-Asians have smaller coronary arteries?

There is a widespread belief that coronary arteries are smaller in Indo-Asians. The aim of the present study was to compare the size of atheroma-free proximal and distal epicardial coronary arteries of Indo-Asians and Caucasians. We analysed normal coronary angiograms from 77 Caucasians and 39 Indo-Asians. The two groups were comparable for dominance of the coronary arteries. Indo-Asian patients had generally smaller coronary arteries, with a statistically significant difference in the mean diameters of the left main coronary artery, proximal, mid and left anterior descending, and proximal and distal right coronary artery segments. There was a non-significant trend towards smaller coronary artery segment diameters for the distal left anterior descending, proximal and distal circumflex, and obtuse marginal artery segments. However, after correction for body surface area, none of these differences in size were statistically significant. Thus, the smaller coronary arteries in Indo-Asian patients were explained by body size alone and were not due to ethnic origin per se. This finding nevertheless has important therapeutic implications, since smaller coronary arteries may give rise to technical difficulties during bypass graft and intervention procedures such as percutaneous transluminal coronary angioplasty, stents and atherectomy. On smaller arteries, atheroma may also give an impression of more severe disease than on larger diameter arteries.

Changes in renal function with percutaneous transluminal coronary angioplasty

There is concern about adverse effects on renal function in patients with prolonged cardiac intervention procedures, when contrast media is used. To investigate this further we studied changes in renal function in 104 patients (79 male, 25 female; mean age 59.2, SD 9.8) undergoing routine elective percutaneous transluminal coronary angioplasty (PTCA), where 28 (27%) patients had concomitant stent implantation. There was associated diabetes in 15 patients (14%) and previous hypertension in 44 (blood pressure >160/90 mmHg, 44%). None of the patients were known to have congestive heart failure at the time of procedure or chronic renal failure (defined as serum creatinine >200 pmol/l). There was no significant change in mean serum urea pre- and post-PTCA (mean change -0.04 mmol/l, paired t-test P=0.90). However, there was a small rise in serum creatinine pre- and post-PTCA of borderline significance (mean change +5.8 micromol/l, P=0.051). Of the whole cohort, 65 patients (63%) had a rise in mean serum creatinine, whilst 45 (43%) showed a rise in serum urea levels. This deterioration in renal function was related to a difference in the procedure duration, but there were no statistically significant differences in mean age or volume of contrast media (Iopamide 340) between patients with or without deterioration in renal function. Patients with a rise in serum creatinine had lower baseline (pre-PTCA) serum urea and serum creatinine levels. In patients undergoing stent implantation, there was a higher quantity of contrast media, screening time and procedure duration. There were no significant differences in age, pre-PTCA serum urea and creatinine levels, and mean change in serum urea or creatinine levels in patients with and without stent usage. Whilst severe renal dysfunction following PTCA is uncommon, we suggest that some caution is necessary during PTCA or other cardiac interventions where more complex or prolonged procedures necessitating large volumes of contrast media use.

Molt-inhibiting hormone mRNA levels and ecdysteroid titer during a molt cycle of the blue crab, Callinectes sapidus

Synthesis of ecdysteroid molting hormones by crustacean Y-organs is believed to be regulated by a neuropeptide, molt-inhibiting hormone (MIH), produced in eyestalk neural ganglia. In the present study, steady-state MIH mRNA and hemolymph ecdysteroid levels were determined by Northern blot and radioimmunoassay, respectively, during the molt cycle of the blue crab, Callinectes sapidus. The level of MIH mRNA dropped steadily during premolt (D1-D4), reaching a minimum in D3/D4, then increased by 10-fold in postmolt (A/B) and remained elevated during intermolt (C4). These stage-specific changes in MIH mRNA levels were accompanied by significant fluctuations in the hemolymph ecdysteroid titer. The ecdysteroid titer increased steadily to a peak of 377.0 ng/ml in D3 of premolt, then dropped to 120.0 ng/ml in D4 (just prior to molting), and was low during postmolt (A/B, 4.4 ng/ml) and intermolt (C4, 3.3 ng/ml). The results represent the first report of developmental changes in MIH gene expression and are generally consistent with the hypothesis that MIH negatively regulates ecdysteroid synthesis in crustaceans.

Molecular cloning of a cDNA encoding molt-inhibiting hormone of the crab, Cancer magister

A neuropeptide molt-inhibiting hormone (MIH) negatively regulates crustacean molting glands (Y-organs). We report here the molecular cloning of a cDNA encoding putative MIH of the Dungeness crab, Cancer magister. A cDNA library was commercially prepared using poly (A+) RNA isolated from C. magister eyestalk neural ganglia. The library was screened using as probe a previously cloned portion of a cDNA encoding MIH of the blue crab, Callinectes sapidus. DNA sequence analysis of one positive clone revealed a 339 base pair open reading frame encoding a 78 amino acid putative MIH and a 35 amino acid signal peptide. The deduced amino acid sequence of C. magister MIH shows high sequence identity (80-98%) with MIH of three other brachyuran crabs, but lower identity (26-45%) with MIH and MIH-like peptides from astacurans and shrimp. Studies using reverse transcription-polymerase chain reaction (RT-PCR) indicate the MIH gene is expressed in eyestalk but not control (muscle, gill, gonad, hepatopancreas) tissue.

Immune-mediated subepithelial blistering diseases of the mucous membranes. Improving the detection of circulating autoantibodies by the use of concentrated serum samples

BACKGROUND AND DESIGN

Comparison of detection of circulating autoantibodies before and after concentration of serum samples from patients with suspected immune-mediated subepithelial blistering diseases of the mucous membranes. We determine whether the use of concentrated serum samples from patients with suspected immune-mediated subepithelial blistering diseases of the mucous membranes improves diagnostic sensitivity for circulating antibodies. We studied 13 patients from a university-based referral practice who had no skin lesions and a scarring subepithelial blistering disease of the mucous membranes. Three of these patients had detectable circulating autoantibodies and 10 had negative indirect immunofluorescence study results using standard techniques. The main outcome measures after concentration of serum samples were detection of circulating autoantibodies on salt-split skin by indirect immunofluorescence, immunoblotting, and immunoprecipitation.

RESULTS

Of the 10 patients in whom circulating autoantibodies had not been detectable with standard techniques, circulating IgG antibodies were detected in 5 (50%) and circulating IgA antibodies in 3 (30%). Of the 3 patients in whom circulating autoantibodies had been detectable with standard techniques, 1 (33%) had circulating IgA antibodies that immunoblotted the 97-kd linear IgA bullous disease antigen only when concentrated serum samples were used.

CONCLUSIONS

The use of concentrated serum samples can improve our ability to detect the presence and antigenic specificity of circulating autoantibodies in patients with suspected but unclassifiable immune-mediated subepithelial blistering diseases of the mucous membranes.

Involvement of microtubules in prothoracicotropic hormone-stimulated ecdysteroidogenesis by insect (Manduca sexta) prothoracic glands

Secretion of ecdysteroid molting hormones by insect prothoracic glands is stimulated by neuropeptide prothoracicotropic hormones (PTTH). Studies reported here were conducted to assess the effects of microfilament and microtubule inhibitors on in vitro ecdysteroidogenesis by prothoracic glands of Manduca sexta. Microfilament inhibitors (cytochalasins B and D) had no effect on basal or big PTTH-stimulated ecdysteroidogenesis. Microtubule inhibitors (colchicine, podophyllotoxin, nocodazole) had no effect on basal ecdysteroid secretion, but suppressed PTTH-stimulated secretion in a concentration-dependent manner. The effect of nocodazole was partially reversible, suggesting it was not due to nonspecific toxicity. Colchicine had no effect on glandular ecdysteroid levels, indicating that inhibition was not due solely to blockage of secretion. The combined results are consistent with the hypothesis that microtubule-mediated transport of ecdysteroid precursors plays a critical role in stimulation of ecdysteroidogenesis by PTTH.

Fibrin D-dimer and beta-thromboglobulin as markers of thrombogenesis and platelet activation in atrial fibrillation. Effects of introducing ultra-low-dose warfarin and aspirin

BACKGROUND

Previous studies have demonstrated increased markers of thrombogenesis in patients with atrial fibrillation (AF), suggesting the presence of a hypercoagulable or prothrombotic state. The objective of this study was to determine the effects of introducing ultra-low-dose warfarin (1 mg), conventional warfarin, and aspirin. (300 mg) therapy on thrombogenesis and platelet activation in AF.

METHODS AND RESULTS

We measured sequential changes in plasma fibrin D-dimer (an index of thrombogenesis) and beta-thromboglobulin (beta-TG, a measure of platelet activation) in 51 patients with chronic AF before and at 2 and 6 weeks after randomization to either 1 mg warfarin or 300 mg aspirin (phase 1). Then all patients were started on conventional warfarin therapy (phase 2) with samples taken 2 and 6 weeks later. Pretreatment results were compared with those from 26 healthy control subjects in sinus rhythm. Baseline (pretreatment) beta-TG and D-dimer levels in patients with AF were elevated compared with those of control subjects (P < .001). In phase 1, there were no significant changes in median levels of fibrin D-dimer or beta-TG, despite warfarin 1 mg or aspirin 300 mg. With standard warfarin therapy (phase 2), there was a reduction in median beta-TG at 6 weeks (P = .025) and a sequential reduction in median D-dimer levels at 2 (P = .001) and 6 (P < .001) weeks compared with baseline levels.

CONCLUSIONS

Patients with AF have increased intravascular thrombogenesis and platelet activation compared with patients in sinus rhythm. Introduction of ultra-low-dose warfarin (1 mg) or aspirin 300 mg does not significantly alter these markers, although conventional warfarin therapy reduces beta-TG and fibrin D-dimer levels. This is consistent with the beneficial effect of full-dose warfarin in preventing stroke and thromboembolism in AF and suggests that ultra-low-dose warfarin and aspirin may not exert similar beneficial effects.

Physician variation in the management of patients with atrial fibrillation

OBJECTIVE

To investigate variations in the management of patients with atrial fibrillation among consultant physicians.

DESIGN

Questionnaire survey.

SUBJECTS

Consultant physicians in England, Wales, and Scotland.

RESULTS

214 consultant physicians (88 cardiologists and 126 non-cardiologists) were surveyed between May and July 1994. Most physicians (47.7%) reported that they saw one to five patients with atrial fibrillation weekly. Some 52% of cardiologists and 40% of non-cardiologists considered that the main factor influencing their decision of whether or not to anticoagulate was the clinical history--that is, heart failure, valve disease, or stroke. When encountering a patient admitted acutely with new onset atrial fibrillation, significantly more cardiologists (66% v 52%, chi 2 = 6.89, P = 0.03) would immediately start anticoagulant treatment, most favouring intravenous heparin. Most physicians would also introduce antiarrhythmic treatment or digoxin, but more cardiologists would attempt immediate pharmacological (39% v 18% of non-cardiologists, P < 0.001) or later electrical (86% v 69%, chi 2 = 11.7, P = 0.003) cardioversion to sinus rhythm, while non-cardiologists tended to prefer "rate control" with digoxin. Although many physicians would not continue antiarrhythmic treatment post-cardioversion, more cardiologists than non-cardiologists would do so (the commonest choice being class III agents) (31% v 17%, P = 0.04). Fewer non-cardiologists would continue anticoagulant treatment post-cardioversion (27% v 69% of cardiologists, chi 2 = 39.8, P < 0.0001). When treating patients with atrial fibrillation, decisions about anticoagulation were usually related to the perceived relative risk of thromboembolism versus haemorrhage derived for each of six case management scenarios in the questionnaire. There was, however, general agreement between cardiologists and non-cardiologists in the use of antithrombotic treatment in the management of lone atrial fibrillation, paroxysmal atrial fibrillation, and patients with atrial fibrillation and mitral valve disease or thyrotoxicosis.

CONCLUSION

There is considerable variation in the management of atrial fibrillation, with more cardiologists than non-cardiologists considering cardioversion to sinus rhythm (and the use of antiarrhythmic and anticoagulant treatment post-cardioversion) and thrombo-prophylaxis with anticoagulation. Guidelines on the management of this common arrhythmia are clearly required.

ABC of atrial fibrillation. Cardioversion of atrial fibrillation

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Differential long-term regulation of MEK and of p42 MAPK in rat glomerular mesangial cells

Constitutive stimulation of the mitogen-activated protein kinase (MAPK) activator MAPK/ERK kinase (MEK) is sufficient to promote long-term events such as cell differentiation, proliferation, and transformation. To evaluate a possible mechanism for the chronic regulation of MEK and p42 MAPK, we studied the long-term effects of fetal bovine serum (FBS), the G protein-coupled receptor agonist endothelin-1 (ET-1), and the protein tyrosine kinase-coupled receptor agonist platelet-derived growth factor BB (PDGF BB) on MEK and p42 MAPK in glomerular mesangial cells (GMC). FBS, ET-1, and PDGF BB led to a time-dependent increase in MEK-1 mRNA and protein expression without altering p42 MAPK mRNA and protein levels. FBS also induced MEK-1 mRNA expression in diverse cell types, including NIH/3T3 fibroblasts, A7r5 vascular smooth muscle cells, and Chinese hamster ovary cells. In GMC, cycloheximide inhibited MEK-1 mRNA induction but stimulated p42 MAPK mRNA expression in the absence and presence of FBS, ET-1, or PDGF. The FBS-induced increase in MEK-1 mRNA was accompanied by a sustained enhancement of MEK activity, as assessed by the ability of immunoprecipitated p45 MEK to activate recombinant p42 MAPK and hence phosphorylate myelin basic protein, and p42 MAPK activity. We conclude that, in GMC, MEK-1 acts like a delayed-early gene and that it can be chronically induced at the mRNA and protein level.