Cell cycle arrest by tyrosine kinase Abl involves altered early mitogenic response.

Activated forms of the nuclear and cytoplasmic tyrosine kinase c-Abl are completely cytoplasmic and oncogenic. The overexpression of c-Abl, and in certain fibroblast cell lines even of v-Abl, leads to a cell cycle arrest revealing an alternative Abl function. To facilitate the analysis of this growth inhibitory function we have taken advantage of regulable Abl-estrogen receptor (ABL:ER) fusion proteins. Oncogenic in the presence of estrogen, they are reversibly switched to inhibit cell proliferation upon removal of hormone. Using this system, we demonstrate that inhibition is effected by Abl derivatives which we have previously shown to be hypo-phosphorylated and to have low kinase activity. Since an almost exclusively cytoplasmic ABL:ER protein is fully growth inhibitory, relevant interactions may occur in the cytoplasm. We identify the cell cycle arrest as an early G1 or G0-like block. Interestingly, growth inhibition correlates with an altered expression pattern of early serum response genes; c-Jun mRNA and c-Fos protein levels are elevated in Abl-blocked cells. In view of the two functional modes of overexpressed Abl proteins, one can speculate that normal c-Abl may be involved in relaying growth regulatory signals from the membrane to the nucleus.

Efficacy and safety of ibutilide fumarate for the conversion of atrial arrhythmias after cardiac surgery.

BACKGROUND: Atrial arrhythmias occur commonly after cardiac surgery and are a cause of significant morbidity and increased hospital costs, yet there is no well-studied treatment strategy to deal with them expeditiously. The purpose of this study was to determine the efficacy and safety of ibutilide fumarate, an approved drug for the rapid conversion of atrial fibrillation and flutter, in patients after cardiac surgery. METHODS AND RESULTS: Patients with atrial fibrillation or flutter occurring 1 to 7 days after surgery and lasting 1 hour to 3 days were randomized to receive two 10-minute blinded infusions of placebo or 0.25, 0.5, or 1.0 mg of ibutilide fumarate. Treatment was considered successful if sinus rhythm was restored for any period of time by hour 1.5. A total of 302 patients were randomized, 201 with fibrillation and 101 with flutter. Treatment with ibutilide resulted in significantly higher conversion rates than placebo, and efficacy was dose related (placebo 15%; ibutilide 0.25 mg 40%, 0.5 mg 47%, and 1.0 mg 57%). Conversion rates at all doses were higher for atrial flutter than for atrial fibrillation. Mean time to conversion decreased as the dose was increased. Polymorphic ventricular tachycardia was the most serious adverse effect and occurred in 1.8% of the ibutilide-treated patients compared with 1.2% of patients who received placebo. CONCLUSIONS: Ibutilide is a useful and safe treatment alternative for the atrial arrhythmias that occur after cardiac surgery.

Gender-specific responses of lean body composition and non-gender-specific cardiac function improvement after GH replacement in GH-deficient adults.

GH deficiency (GHD) in adulthood is accompanied by physical and psychological impairments. One hundred fifteen patients (67 male, 48 female) with pronounced GHD were enrolled in a randomized, double-blind, placebo-controlled study with objectives that included effects on body composition, cardiac structure, and function and safety of replacement therapy with recombinant human GH (Saizen). Sixty patients (31 male, 29 female) received GH at a dose of 0.005-0.010 mg/kg.d, and 55 patients (36 male, 19 female) received placebo for 6 months. Assessment of body composition by dual-energy x-ray absorptiometry demonstrated a treatment difference in lean body mass increase of 2.1 kg (between-group comparison, P < 0.0001), which was significantly greater among males than females (P < 0.0001) [males: GH, +3.13 kg (2.42, 3.84); placebo, +0.11 kg (-0.60, 0.82); and females: GH, +0.64 kg (-0.15, 1.44); placebo: -0.90 kg (-2.20, 0.39)] [mean change 0-6 months (95% confidence limits)] and was associated with IGF-I changes. The decrease in fat mass of 2.8 kg (between-group comparison, P < 0.0001) noted by DEXA was also evident from bioelectric impedance and anthropometric measurements. Echocardiography showed comparable improvement in left ventricular systolic function after GH treatment in both genders. End-systolic volume decreased by 4.3 +/- 10.5 ml (from 35.8 +/- 17.6 ml; between-group comparison, P = 0.035) and ejection fraction increased by 5.1 +/- 10.0% (from 55.0 +/- 11.2%; between-group comparison, P = 0.048), approaching normalcy. Diastolic function did not change as assessed by isovolumic relaxation time, early diastolic flow, diastolic flow secondary to atrial contraction, or ratio of peak mitral early diastolic and atrial contraction velocity. GH treatment was well tolerated, with adverse events primarily related to effects on fluid balance. No apparent relationship between IGF-I levels and the occurrence or severity of adverse events was identified. In conclusion, GH replacement therapy in adults with GHD demonstrated beneficial effects on lean body mass composition that was more pronounced in males than females. In contrast, cardiac function improvement appears to benefit both genders equally.

Growth inhibition by Abl requires an interplay of its SH2 and tyrosine kinase domains.

Overexpression of c-Abl tyrosine kinase can be growth inhibitory in certain fibroblast cell lines. Using a series of conditional chimeras between Abl and Src, we have now further dissected the Abl protein to determine which domains are required for this function. We found that growth inhibition, unlike transformation by oncogenic forms of Abl, is dependent on the presence of the cognate SH2 and tyrosine kinase domains. Since growth inhibition correlates with low tyrosine kinase activity, it may involve highly specific interactions of target proteins with both domains without the processivity of phosphorylation associated with oncogenic Abl.

Reproducibility of programmed electrical stimulation responses in patients with ventricular tachycardia or fibrillation associated with coronary artery disease.

Invasive electrophysiologic studies were performed in 102 patients with sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) using an aggressive programmed electrical stimulation (PES) protocol. The study was repeated after 2.0 +/- 2.9 days in all patients with no intercurrent changes in antiarrhythmic therapy. Patients with coronary artery disease (n = 72) were identified and PES results of these patients were analyzed and compared with results of patients without coronary artery disease. Multiple clinical and electrophysiologic factors were analyzed to determine any association with concordance of PES responses. No significant difference in concordance of PES responses was found in the 2 groups of patients. PES responses were groups into 3 categories: (1) noninducible, (2) nonsustained VT, and (3) sustained VT. Kappa values of PES responses of noninducible and sustained VT in both groups were higher and therefore the PES responses were more reproducible than nonsustained VT. The induction of sustained monomorphic VT was more reproducible than a PES response of nonsustained or sustained polymorphic VT. Inducible sustained VT with a rate of greater than or equal to 250 beats/min was less reproducible than induction of sustained VT with a rate less than 250 beats/min. Induction of VT by 3 extrastimuli was less reproducible than with any other mode. This short-term variability may account for false negatives associated with PES-directed antiarrhythmic therapy. Because of these findings, it is recommended that nonsustained VT and sustained polymorphic or rapid polymorphic VT should not be used as PES end points to guide antiarrhythmic therapy.

Long-term arrhythmic outcome in survivors of ventricular fibrillation with absence of inducible ventricular tachycardia.

While programmed electrical stimulation of the heart is useful in directing therapy in cardiac arrest survivors who exhibit inducible ventricular tachycardia (VT), controversy exists as to the risk of recurrent ventricular fibrillation (VF) and need for antiarrhythmic therapy in patients without inducible VT during drug-free control programmed stimulation studies. In this study, the clinical features and arrhythmic outcome of 43 survivors of VF without inducible VT at control programmed stimulation were examined. In 38 patients, factors that may have played a potentiating role in the genesis of VF included ischemia in 15, proarrhythmia in 18, rapid rate response to atrial fibrillation in 3 and acute alcoholism in 2. Three patients required antiarrhythmic drugs for supraventricular tachyarrhythmia and 40 patients were discharged without antiarrhythmic therapy. At 32 +/- 21 months (range 1 to 82), 37 (92%) have remained free of arrhythmic recurrence while 3 have had sustained subsequent major arrhythmic events (syncope 1 patient, VF 1, sudden cardiac death 1). Thus, survivors of VF without inducible VT at drug-free control programmed stimulation are characterized by (1) potentiating factors--often identifiable and correctable--that may be important to the genesis of VF; (2) generally low risk of arrhythmic recurrence; and (3) effective long-term management often achieved without the use of additional antiarrhythmic drugs or antitachycardia/defibrillation devices.

Safety and efficacy of sotalol in patients with drug-refractory sustained ventricular tachyarrhythmias.

The safety and efficacy of oral sotalol, an investigational beta-adrenergic blocker with class III antiarrhythmic drug properties, were examined in a multicenter study in 236 patients with sustained ventricular tachyarrhythmias. In 104 patients, the index arrhythmia was a cardiac arrest, and all patients had undergone at least 3 previous unsuccessful antiarrhythmic trials (mean = 5 per patient). In the 106 patients assessed by programmed electrical stimulation, sotalol completely suppressed induction of ventricular tachycardia (VT) in 33 (31%) and rendered VT slower (greater than 100 ms prolongation of cycle length) or more difficult to induce in 29 (27%). Using continuous 24-hour ambulatory monitoring methods, sotalol complete- and partial-response rates were 51 and 12%, respectively. Of the 236 acute-phase patients, 151 were discharged receiving long-term sotalol therapy. The median sotalol dose was 480 mg/day. At a mean follow-up of 346 +/- 92 days, 27 patients (18%) had recurrence of sustained arrhythmia; 9, sudden death; 11, sustained VT; 5, automatic defibrillator discharge; and 2, syncope. Adverse effects forced discontinuation of therapy in 10 patients (7%): 6 secondary to symptomatic bradyarrhythmia, 2 due to refractory heart failure, 1 due to torsades de pointes, and 1 from bronchospasm. Life-table analysis of sotalol's overall long-term efficacy at 6, 12 and 18 months were 80, 76 and 72%, respectively. Although mean follow-up was short (less than 1 year), neither acute-phase programmed stimulation nor 24-hour ambulatory monitoring responses were significantly predictive of subsequent arrhythmic outcome. Proarrhythmia was documented in 18 patients (7%), 17 during the acute phase and 1 during long-term follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Physical and genetic mapping of the CDR gene with particular reference to its position with respect to the FRAXA site.

This study narrows down the localization of the gene coding for the cerebellar degeneration-related protein (CDR 34) to the upper boundary of the FRAXA and reports the finding of two common RFLPs respectively identified at an RsaI site flanking the 3' end of the gene and at a Hincll site flanking its 5' end. Segregation analysis carried out in the CEPH-pedigrees for the new CDR/RsaI-RFLP versus other polymorphic loci of the region has established a tight linkage with the markers DXS105/DX98 and absence of measurable linkage with two clusters of markers respectively located proximally to the FRAXA (F9, DXS102, DXS51, and DXS369) or distally to it (DXS52, DXS304). In addition, two recombinants were found among 23 scorable sibs identified in the Sardinian pedigrees segregating for the Martin-Bell Syndrome (MBS) and the CDR/RsaI variants. The overall evaluation of the in situ and genetic data reported suggest that the CDR locus 1) is located at the upper boundary of the FRAXA site; 2) is distal to DXS51 and proximal to DXS 389; and 3) segregates in a close linkage association with the loci DXS98 and DXS105 and, to a lesser extent, with the locus for MBS.

Circulating IGF-I levels in monitoring and predicting efficacy during long-term GH treatment of GH-deficient adults.

OBJECTIVE: To investigate the effects of long-term GH in GH-deficient adults, as predicted by IGF-I levels. METHODS: Patients received GH, 5 microg/kg per day for 1 Month and 10 microg/kg per day for another 12-30 Months. Changes in body composition, cardiac structure/function, serum lipids and quality of life were measured. RESULTS: There was a significant increase in lean body mass (LBM) (2.21 kg; P<0.0001) after 6 Months, which was sustained throughout treatment. A larger increase occurred in males than females (2.97 vs 1.19 kg; P<0.0001). Total fat mass was reduced (2.56 kg; P<0.0001 (3.26 kg males, 1.63 kg females)). Responsiveness to GH varied greatly, but LBM changes correlated with IGF-I changes (P<0.004). Furthermore, thinner patients experienced greater and progressive LBM increases. There was an increase in ejection fraction (3.85+/-9.95%; P=0.0002) after 6 Months, sustained to 18 Months. These cardiac effects were equal for males and females, and did not correlate with IGF-I levels. Serum low-density lipoprotein/high-density lipoprotein ratios decreased within 6 Months, and were sustained thereafter. Quality of life improved significantly after 6 Months, an effect that was sustained/enhanced as treatment continued. No major adverse events were identified. CONCLUSIONS: Improved body composition is both reflected by IGF-I changes and predicted inversely by baseline adiposity. Other effects of GH replacement on cardiac function, dyslipidaemia and quality of life, however, do not correlate with circulating IGF-I concentrations. Our findings validate the importance of sustained GH therapy, but caution on the interpretation of IGF-I levels in monitoring the long-term effects of GH treatment.

Long-term prognosis after myocardial infarction. Who is at risk for sudden death?

Patients who have survived myocardial infarction may be at risk for recurrent infarction or sudden death within the first year. Clinical factors that identify high-risk patients include the following: Poor left ventricular function Presence of spontaneous ventricular ectopy Abnormal signal-averaged electrocardiogram Decreased heart rate variability Exercise-induced depression of the ST segment Inducible ventricular tachyarrhythmia When these high-risk patients are identified, appropriate strategies (eg, use of antiarrhythmic agents or an implantable cardioverter-defibrillator) may improve outcome.

Concurrent myocardial and cerebral infarctions after intranasal cocaine use.

BACKGROUND AND PURPOSE: Cardiac and cerebrovascular complications associated with cocaine abuse have increasingly been reported, but concurrent development of cocaine-induced cardiac disease and stroke has rarely been reported. CASE DESCRIPTION: A 37-year-old man with a remote history of intravenous heroin and amphetamine use, cardiomyopathy, and recent cocaine use developed chest pain and ventricular tachycardia 30 minutes after intranasal cocaine hydrochloride use and jogging on a cold winter morning. Ventricular tachycardia was converted to atrial fibrillation. He was proven to have a small myocardial infarction. Within 6 hours of cocaine use he suffered a left hemisphere stroke. Cardiac electrophysiologic evaluation revealed inducible ventricular tachycardia. CONCLUSIONS: To our knowledge, this is the first report of concurrent myocardial infarction, life-threatening ventricular arrhythmias, and cerebral infarction temporally related to cocaine use. It is probable that one mechanism by which cocaine use causes stroke is to trigger expression of a known cardiac source of embolism.

Phrenic nerve conduction studies: a new technique and its application in quadriplegic patients.

Although a few reports of phrenic nerve stimulation have appeared over the past dozen years, electromyographers have not readily accepted these methods. Perhaps this is because the techniques are considered unreliable, or because there is a major element of patient discomfort. In this study a simple, safe, and relatively painless procedure was devised for placing a needle near the phrenic nerve for use as a stimulating electrode. Also, the positions of the recording electrodes were relocated until a site was found that consistently provided a response with an initial negative deflection in all subjects. Emphasis has been on improving technique. A group of 60 nerves in 30 normal subjects was studied. The mean latency was 7.44 +/- 0.59msec, and the mean difference between right and left was 0.08 +/- 0.42msec. A response was obtained in all nerves examined. In addition, 13 patients with quadriplegia due to spinal cord injury were studied. This method now permits reliable analysis of localized phrenic nerve lesions and abnormalities induced in either the phrenic nerve or diaphragm by generalized disease processes.

SARs stimulate but do not confer position independent gene expression.

Two minimal scaffold-associated regions (SARs) from Drosophila were tested in stably transformed cells for their effects on the expression of reporter genes. The expression of genes bounded by two SARs is consistently stimulated by about 20- to 40-fold, if the average of a pool of cell transformants is analyzed. However, analysis of individual, stable cell transformants demonstrates that flanking SAR elements do not confer position-independent expression on the reporter gene and that the extent of position-dependent variegation is similarly large with or without the flanking SAR elements. The SAR stimulation of expression is observed in stable but not in transiently transfected cell lines. The Drosophila scs and scs' boundary elements, which do not bind to the nuclear matrix in vitro, are only about one-tenth as active as SARs in stimulating expression in stable transformants. Interestingly, the SAR stimulatory effect can be blocked by a fragment containing CpG islands (approximately 70% GC), if positioned between the SAR and the enhancer. In contrast, when inserted in the same position, control fragments, such as the scs/scs' elements, do not interfere with SAR function.

Factors determining programmed stimulation responses and long-term arrhythmic outcome in survivors of ventricular fibrillation with ischemic heart disease.

The clinical and angiographic features of 38 patients with ischemic heart disease and nonacute infarction pre-hospital ventricular fibrillation (VF) were examined as a function of their drug-free programmed electrical stimulation (PES) responses. Twenty-two patients (58%) had inducible ventricular tachycardia (VT) at drug-free PES (group I) and 16 patients (42%) did not (group II). Group I had more patients with: (1) remote infarction (22 of 22 vs 2 of 16; p less than 0.01; (2) history of congestive failure (16 of 22 vs 0 of 16; p less than 0.01); (3) prior cardiac arrest (11 of 22 vs 0 of 16; p less than 0.01); (4) left ventricular (LV) ejection fraction less than 40% (19 of 22 vs 1 of 16; p less than 0.01); and (5) akinetic or dyskinetic LV wall motion (22 of 22 vs 2 of 16; p less than 0.001). Group II had more patients with: (1) LV segments at "ischemic jeopardy" (16 of 16 vs 14 of 22; p less than 0.01) and (2) factors suggestive of ischemia at the onset of VF (13 of 16 vs 1 of 22; p less than 0.001). Inducible VT (IVT) was suppressed in 16 of the 20 group I patients surviving hospitalization while four were discharged with persistence of IVT despite therapy. At 27 +/- 15 months, all four with persistent IVT had a recurrence of their arrhythmia. In the 16 group II patients, therapy was limited to antiischemic measures: coronary bypass in 12, propranolol in 3, and angioplasty in one. At 38 +/- 9 months, no group II patient has had a recurrence of his arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

A cDNA clone for a novel nuclear protein with DNA binding activity.

In an effort to identify trans-acting factors regulating specific genes, we cloned a novel human gene, DBP-5. The cDNA clone contains a predicted open reading frame coding for a potential 1,179 amino acid protein. The mRNA corresponding to DBP-5 is ubiquitously distributed, and the gene is phylogenetically conserved. Immunofluorescence analyses with several cell lines indicate that the protein is localized to the nucleus. Sequence analysis revealed unusual features of the predicted protein structure, including four completely conserved repeats. The phylogenetic conservation of DBP-5, the ubiquity of its expression, its nuclear localization, and its ability to bind DNA sequences, raise the possibility that DBP-5 may play a role in the organization of interphase chromatin and/or in transcriptional regulation.

Pvu II polymorphism of low density lipoprotein receptor gene and familial hypercholesterolemia. Study of Italians.

Familial hypercholesterolemia is a metabolic disorder inherited as an autosomal dominant trait characterized by an increased plasma low density lipoprotein (LDL) level. It has been demonstrated that the disease is caused by several different mutations in the LDL receptor gene. Although early identification of individuals carrying the defective gene could be useful in reducing the risk of atherosclerosis and myocardial infarction, the available techniques for determining the number of the functional LDL receptor molecules are not sufficiently accurate. The recent isolation of the LDL receptor gene now makes it possible to use restriction fragment length polymorphisms to study the inheritance of the defective allele in families with familial hypercholesterolemia. In the present study, we report the use of a Pvu II restriction fragment length polymorphism to follow the inheritance of familial hypercholesterolemia in a total of 79 patients from 37 different families. This restriction fragment length polymorphism allowed unequivocal diagnosis in 32.5% of the cases. Furthermore, in the Italians studied, the absence of a polymorphic Pvu II cutting site (P1 allele) was found to be strongly associated with familial hypercholesterolemia.

Use of three DNA polymorphisms of the LDL receptor gene in the diagnosis of familial hypercholesterolemia.

Familial hypercholesterolemia (FH) is an autosomal dominant metabolic disorder caused by several different mutations in the low density lipoprotein (LDL) receptor gene. This large number of different mutations, often undetectable in Southern blotting, makes it impossible directly to diagnose the disease. However, restriction fragment length polymorphisms (RFLPs) can be used to follow the inheritance of the defective gene in FH families. In the present study, we report the use of three RFLPs, detected by PvuII, ApaLI and AvaII restriction enzymes, to determine the haplotypes of normal and defective LDL receptor genes in 61 families with FH and in 128 normal individuals. Two of the nine haplotypes were significantly more often associated with the affected genes, whereas one was significantly less frequent. Although none of the associations was strong enough to allow diagnosis in individuals, it was possible, using the three RFLPs, to identify the haplotype of the affected gene in 57 families and to carry out unequivocal diagnosis in 67% of the cases. In four families, PvuII and AvaII detected an abnormal fragment co-segregating with the disease, thus increasing the percentage of diagnosis to 73.4% of the cases.

Determinants of psychiatric inpatient admission to general hospital psychiatric wards: an epidemiological study in a region of central Italy.

OBJECTIVE: To determine which factors contribute to the decision to admit individuals to psychiatric wards in general hospitals. METHOD: Data on 1,379 individuals undergoing psychiatric evaluation in eight emergency rooms in a region of central Italy were collected. A logistic regression analysis was used to evaluate the likelihood of psychiatric admission considering the independent effects of demographic, social, and clinical factors and of the history of psychiatric treatment. RESULTS: The adjusted odds ratio for psychiatric admission significantly increased with the following variables: severity of symptoms; presence of paranoid states and schizophrenic psychoses, affective psychoses and acute psychotic conditions (with neurotic disorders used as reference); a history of outpatient treatment; the presence of a staff member of a community mental health facility upon presentation at the emergency room; and the availability of beds in the psychiatric ward. CONCLUSION: The independent effect played by the presence of a staff member of a community mental health facility is of particular interest, suggesting the existence of a collaborative relationship between inpatient and outpatient services.

Amiodarone in patients with previous drug-mediated torsade de pointes. Long-term safety and efficacy.

The safety and efficacy of long-term amiodarone therapy were examined in 12 patients who had previously developed torsade de pointes as a complication of previous antiarrhythmic therapy. The QTc intervals were determined at the time of torsade de pointes (570 +/- 40 ms), after 7 days of amiodarone loading (490 +/- 70 ms), and after 3 months of chronic amiodarone administration (580 +/- 80 ms). Compared to a drug-free control period, QTc was significantly prolonged (P less than 0.05) at the time of torsade de pointes, after amiodarone loading, and after 3 months of amiodarone therapy. The QTc intervals at the time of torsade de pointes and after chronic amiodarone treatment were not significantly different. At 16 +/- 7 months of follow-up, all patients remained free of subsequent torsade de pointes, syncope, or sudden death. In addition, 5 of 6 patients with a history of sustained ventricular tachycardia remained free from arrhythmic recurrence despite persistence of inducible ventricular tachycardia during programmed stimulation studies done before discharge. We conclude that amiodarone can often be used safely and effectively in patients who have previously had an episode of drug-mediated torsade de pointes. Amiodarone-induced QTc prolongation, even when marked, does not predict recurrent torsade de pointes. These observations also suggest that the propensity for a drug to produce this arrhythmia is dependent on other electrophysiologic effects in addition to its ability to simply lengthen repolarization.