Circadian variation of sustained ventricular tachycardia in patients subject to standard adrenergic blockade

Morning peaks in the circadian variation of sustained ventricular tachycardia (VT) may reflect the contribution of sympathetic activation to onset of VT. We hypothesized that adrenergic blockade would eliminate this morning peak. Fifty-four patients using a defibrillator had 1114 time-stamped episodes of VT requiring therapy with a device: 1012 episodes with and 102 episodes without antiadrenergic medications. Nine patients had episodes both with and without antiadrenergic medication and were examined separately. In patients taking antiadrenergic agents, data fitted to a harmonic regression model revealed a morning peak at 9:00 AM (R2= 0.542; p < 0.05), with a secondary peak at 4 PM. Those not receiving antiadrenergic therapy had a similar morning peak. Antiadrenergic agents as used in standard clinical practice do not prevent circadian variation in onset of VT. This variation may be mediated by systems other than adrenergic receptor-linked activation or may reflect inadequacy of adrenergic blockade in standard clinical dosing.

Do permanent pacemakers need an insulative coating? Results of a prospective randomized double-blind study

During conventional manufacturing of implanted pulse generators (IPGs), an insulative coating is often applied to prevent local muscle stimulation and myopotential sensing in unipolar pacing. This can limit the orientation of the IPG into its pocket, be a potential source of muscle stimulation via coating scratches, and result in an increase in IPG production costs. We hypothesized that advances in the design and construction of current IPGs and leads obviates the need for an insulative coating of the IPG. Using a double-blind prospective randomized design, 39 patients were implanted with either coated or uncoated otherwise identical IPGs (19 dual, 20 single chamber). All testing was done in unipolar and bipolar mode in both channels. A strength-duration curve for muscle stimulation was constructed for all patients with muscle stimulation. Myopotential sensing was established during isometric exercise. At 6-month follow-up when tested in unipolar mode, 3 of 15 (20%) patients with coated IPGs and 3 of 20 (15%) with uncoated IPGs had muscle stimulation at 5.0 V/1.5 ms or lower (P = NS). No patients in either population had muscle stimulation at their normally programmed output. Myopotential sensing occurred in all patients in unipolar mode at a mean of 2.29 +/- 1.3 mV and 2.73 +/- 1.14 mV for coated versus uncoated, respectively (P = NS). The statistical power of these negative observations was 80%. An insulative coating for pacemakers does not appear to alter sensing performance or cause a significant difference in the occurrence or characteristics of muscle stimulation.

Serial measures of sinoatrial and atrioventricular nodal function in ambulatory patients

We hypothesized that the outpatient assessment of SA and AV nodal (SAN, AVN) function could be a useful tool to determine the effectiveness of drugs and other treatments. We sought to examine the reproducibility, safety and ease of acquiring serial measurements of these parameters. Ten patients with permanent pacemakers underwent low current chest wall stimulation while their device was programmed to unipolar atrial triggered mode. Measurements at multiple conditioning drive train frequencies were obtained for: sinus nodal recovery time (SNRT); corrected sinus nodal recovery time (CSNRT); SA conduction time (SACT); AVN block cycle length (AVNBCL); and AVN effective refractory period (AVNERP). AVN function curves were also constructed. All studies were repeated after 2 weeks. Measures of sinus nodal and AVN function did not show significant differences between the two studies. The following co-efficients of correlation were obtained: SNRT800, r = 0.79; CSNRT800, r = 0.71; SNRT600, r = 0.71; CSNRT600, r = 0.44; SACT, r = 0.75; AVNBCL, r = 0.98; AVNERP800, r = 0.55; and AVNERP600, r = 0.99. AVN function curves did not significantly differ between week 1 versus week 2 at conditioning drive trains of either 800 ms or 600 ms. These data suggest that serial noninvasive electrophysiological measures of AVN and SAN function are reproducible over 2 weeks. Using data in this study, estimates of the sample size necessary for the evaluation of the effects of investigational drugs on the SAN and AVN in future studies are possible.

Relation of direct assessment of cardiac autonomic function with metaiodobenzylguanidine imaging to heart rate variability in diabetes mellitus

Myocardial metaiodobenzylguanidine uptake predicts autonomic function in patients with diabetes mellitus and is significantly related to indexes reflecting sympathetic neural modulation of heart rate variability.

A population-based method for the estimation of defibrillation energy requirements in humans. Assessment of time-dependent effects with a transvenous defibrillation system

BACKGROUND

A weighted logistic regression analysis was developed to allow pooling of patient data for the study of the stability of defibrillation energy requirements with a new nonthoracotomy lead defibrillation system.

METHODS AND RESULTS

One hundred twenty patients were prospectively studied with a single-model nonthoracotomy implantable cardioverter defibrillator (ICD) system at the time of implant and at 3 months. The pooled data of all shocks delivered to all patients were fitted to a logistic function to construct a defibrillation voltage/energy dose-response relationship. The crude logit curve was weighted in quartiles according to the average shock energy delivered per patient. Shocks at implant (n = 802; 6.6 +/- 2.5 shocks/patient) and follow-up (n = 292; 2.4 +/- 1.2 shocks/patient) were analyzed. The modeled voltage/energy required for 50% successful defibrillation (95% CI) in the pooled data was 367 V (273, 461) and 9.8 J (6.7, 12.9) at implant and 338 V (264, 412) and 10.5 J (8, 13.0) at follow-up. The conventional measure of lowest successful voltage/energy (95% CI) was 430 V (411, 449) and 12.1 J (11, 13.2) at implant and 415 V (391, 439) and 11.3 J (10, 12.6) at follow-up. There were no statistically significant differences between implant and follow-up energy requirements with either method.

CONCLUSIONS

The nonthoracotomy lead system used in this study demonstrated stability of defibrillation energy requirements at implant and 3-month follow-up. A new technique for the estimation of the defibrillation energy dose-response relationship was derived by using a weighted logistic regression analysis.

Dual device therapy in the setting of changing ICD technology: device-device interaction revisited

This case report concerns an adverse device-device interaction between a replacement ICD and a dual chamber rate responsive pacemaker. It was observed that subtle changes in the design of sensing circuits between an older first-generation ICD and the newer third-generation ICD device led to unexpected and dramatic changes in the interactive behavior of a dual device system. The new ICD was connected to chronically implanted hardware. The sensing behavior of the newer ICD included a shorter time constant in the decay of the automatic gain control function, resulting in triple sensing of both the atrial and ventricular paced stimuli and the evoked QRS complex. Physicians should be aware of new design changes in the future so as to anticipate such interactions. In the setting of rapidly changing technology, extra caution must be exercised when choosing to implant two devices in the same patient.

Early switch from intravenous to oral antibiotics in hospitalized patients with infections: a 6-month prospective study

We assessed what percentage of hospitalized patients treated with intravenous antibiotics would be candidates for early switch to oral therapy, and evaluated the clinical outcomes of patients after the switch. All hospitalized patients in whom an intravenous antibiotic was prescribed for treatment of an infection were prospectively screened to identify candidates for switch in therapy. Of the 655 patients treated with intravenous antibiotics, 300 (46%) were candidates for a switch, and the change was implemented in 262 (40%). Of the 171 evaluable patients, the switch was associated with clinical cure in 167 (98%) and failure in 4 (2%). In hospitalized patients with infections, the duration of intravenous antibiotic therapy can be minimized with early switch to oral therapy. This practice is associated with good patient outcome.

Human fibroblasts bind directly to fibrinogen at RGD sites through integrin alpha(v)beta3

Fibroblast migration into the blood clot initially filling a wound requires close interaction between fibroblasts and the matrix of the fibrin clot. However, very little is known about the specific receptor-ligand interactions that mediate fibroblast attachment to fibrin. Using an attachment assay developed to measure even relatively weak interactions, we demonstrate here that normal human dermal fibroblasts can attach to substrates coated with fibrinogen, fibrin, or the fibrinogen breakdown product I-9D. Fibroblast attachment to these ligands did not require the presence of fibronectin on the cell surface or as a component of the substrate. Cells treated with cycloheximide and monensin, to limit the synthesis and secretion of endogenous fibronectin, attached as well as untreated cells. The synthetic peptide GRGDS inhibited adhesion to fibrinogen, fibrin, and fibrinogen I-9D by about 60%, while the control peptide GRGES had no substantial effect. We conclude that attachment to these ligands is mediated at least partially by direct interactions between the substrates and one specific receptor, the integrin alpha(v)beta3. Affinity chromatography demonstrated that alpha(v)beta3 from detergent lysates of fibroblasts bound to a fibrinogen matrix and was eluted with EDTA. Furthermore, antibodies against the alpha(v)beta3 complex or against the alpha(v) subunit inhibited fibroblast attachment to fibrinogen and fibrin by 50-70%. An inhibitory antibody against the integrin beta1 subunit had no effect. The observation that integrin antagonists could not produce complete inhibition suggests that there may be other fibroblast cell surface proteins that can bind directly to fibrinogen.

Tedisamil increases coherence during ventricular fibrillation and decreases defibrillation energy requirements

INTRODUCTION

Drugs which primarily prolong cardiac refractoriness decrease defibrillation voltage and energy requirements in animals and man. The effect of such drugs on ventricular fibrillation itself is not well understood. We hypothesized that tedisamil, an investigational antiarrhythmic drug which blocks Ito and IK repolarizing potassium channels, would increase organization of epicardial electrograms during ventricular fibrillation while it lowered defibrillation energy requirements.

METHODS

We measured magnitude-squared coherence, a measure of spatial organization, and ventricular fibrillation (VF) cycle length, ventricular effective refractory period (VERP), and monophasic action potential duration (APD90) as well as defibrillation energy threshold (E50) at baseline and after 150 micrograms/kg of tedisamil (n = 13) or saline control (n = 6) in an open chest dog model.

RESULTS

After tedisamil, mean magnitude-squared coherence increased by 132 +/- 133%, from 0.15 +/- 0.08 to 0.31 +/- 0.16 (P < 0.001); VF cycle length increased from 121 +/- 24 to 190 +/- 63 ms (P < 0.001) and became more regular, with the coefficient of variation between adjacent VF intervals decreasing from 14.1 +/- 6.9 to 3.9 +/- 2.2% (P < 0.001). Mean E50 decreased from 8.9 +/- 3.8 to 6.1 +/- 2.7 joules (P < 0.001); VERP increased from 158 +/- 30 to 201 +/- 31 ms (P < 0.001), and APD90 increased from 177 +/- 25 to 244 +/- 45 ms (P < 0.001) after tedisamil. No electrophysiologic parameter was changed after saline infusion.

CONCLUSIONS

Tedisamil increases both spatial coherence and temporal regularity of ventricular fibrillation. These effects on 'order' during VF may be in part responsible for the observed reduction in defibrillation energy requirements.

Electrophysiologic mechanisms of antiarrhythmic efficacy of a sotalol and class Ia drug combination: elimination of reverse use dependence

OBJECTIVES

We sought to determine the electrophysiologic mechanisms explaining the efficacy of combination therapy with DL-sotalol and a type Ia drug in the treatment of ventricular tachycardia (VT).

BACKGROUND

Combination antiarrhythmic drug therapy with low dose DL-sotalol plus a type Ia antiarrhythmic agent has been shown to prevent spontaneous and induced VT. The mechanisms underlying the efficacy of this drug combination have not been fully elucidated.

METHODS

We studied 32 patients with spontaneous sustained VT by using programmed electrical stimulation in the drug-free condition and after treatment with DL-sotalol (average dose [mean +/- SE] 151 +/- 8 mg/day) and a class Ia agent (quinidine, 1,337 +/- 59 mg/day, or procainamide, 2,083 +/- 327 mg/day). Sustained VT was induced in all patients at baseline study, and induction was reattempted during drug therapy. Monophasic action potential duration at 90% repolarization (APD90) and ventricular effective refractory period (ERP) were recorded with use of a contact electrode.

RESULTS

Ventricular ERP increased from 258 +/- 4 ms at baseline to 310 +/- 6 ms at a 600-ms drive cycle length (DCL600) with treatment (p < 0.001). APD90 increased from 288 +/- 6 ms by +10.1% at DCL600 and from 267 +/- 7 ms by +13.3% at a 400-ms drive cycle length (DCL400) (p < 0.001). Paced QRS duration increased from 141 +/- 3 to 158 +/- 6 ms at DCL400 (p < 0.05). At baseline, the shortest achieved coupling interval between successive propagated extrastimuli decreased progressively with respect to the first extrastimulus, following double and triple extrastimuli, at both DCL600 (-14.0% and -20.0%, respectively) and at DCL400 (-16.4% and -22.4%, respectively). This "peeling back" of refractoriness was attenuated on therapy with sotalol plus a class Ia antiarrhythmic agent to -6.7% and -10.5% (DCL600, p < 0.05), and -8.1%, -9.5% (DCL400, p < 0.05), for double and triple extrastimuli, respectively. The absolute prolongation of functional refractory periods by the drug combination increased with successive extrastimuli, from 55 +/- 6 ms for the V1V2 interval to 75 +/- 6 ms for V2V3 and 67 +/- 6 ms for V3V4 at DCL600, and from 51 +/- 5 ms for V1V2 to 69 +/- 6 ms for V2V3 and 74 +/- 7 ms for V3V4 at DCL400 (p < 0.001).

CONCLUSIONS

The combination of low dose sotalol and a class Ia agent greatly prolongs refractoriness. The magnitude of the effect increases at shorter coupling intervals.

Modulating autoimmune responses to GAD inhibits disease progression and prolongs islet graft survival in diabetes-prone mice

In nonobese diabetic (NOD) mice, beta-cell reactive T-helper type 1 (Th1) responses develop spontaneously and gradually spread, creating a cascade of responses that ultimately destroys the beta-cells. The diversity of the autoreactive T-cell repertoire creates a major obstacle to the development of therapeutics. We show that even in the presence of established Th1 responses, it is possible to induce autoantigen-specific anti-inflammatory Th2 responses. Immune deviation of T-cell responses to the beta-cell autoantigen glutamate decarboxylase (GAD65), induced an active form of self-tolerance that was associated with an inhibition of disease progression in prediabetic mice and prolonged survival of syngeneic islet grafts in diabetic NOD mice. Thus, modulation of autoantigen-specific Th1/Th2 balances may provide a minimally invasive means of downregulating established pathogenic autoimmune responses.

Mesenchymal cell activation is the rate-limiting step of granulation tissue induction

During wound repair a 3-day lag occurs between injury and granulation tissue development. When full-thickness, 8-mm-round, excisional wounds were made in the paravertebral skin of outbred Yorkshire pigs and harvested at various times, no granulation tissue was observed before day 4. Day 4 wounds were 3% filled with granulation tissue, day 5 wounds 48% filled, and day 7 wounds 88% filled. The prerequisites for granulation tissue induction are not known but hypothetically include fibrin matrix maturation or cell activation. To examine whether matrix maturation was necessary, wounds were allowed to heal for 5 or 7 days and then aggressively curetted, resulting in the formation of fresh fibrin clots in the newly formed wound spaces. In contrast to original wounds, no lag phase was observed; wounds curetted on day 5 were 23% filled with granulation tissue 1 day later and 99% filled 3 days later, whereas wounds curetted on day 7 were 47% filled 1 day later and completely filled within 2 days. Thus, granulation tissue formation resumed promptly and independently of fibrin clot matrix maturation. This observation suggested that mesenchymal cell activation might be the rate-limiting step in granulation tissue formation. To address this hypothesis more directly, cultured porcine or human fibroblasts, grown to 80% confluence in Dulbecco's minimal essential medium plus 10% fetal calf serum, were added to new wounds. These wounds were sealed with a freshly made exogenous fibrin clot. In some wounds, platelet releasate was added to the fibrin clot. Granulation tissue did not form in day 3 wounds, which had received either fibrin alone, fibrin and platelet releasate, or fibrin and fibroblasts. In contrast, granulation tissue was observed in wounds receiving fibrin, human fibroblasts, and platelet releasate. By day 4, wounds receiving cultured human fibroblasts, fibrin, and platelet releasate were 14% filled with granulation tissue compared with less than 4% granulation tissue in control wounds. Thus, fibroblast activation is a limiting step of granulation tissue formation, and continued cell stimulation is required for accelerated development.

d-Sotalol decreases defibrillation energy requirements in humans: a novel indication for drug therapy

INTRODUCTION

We assessed the effect of d-sotalol on defibrillation voltage and energy requirements in patients undergoing automatic defibrillator implantation. Drugs that primarily prolong cardiac refractoriness generally decrease the energy requirements for defibrillation in animal models. Despite the widespread use of antiarrhythmic drugs in patients with implanted cardioverter defibrillators, the effect of such drugs on defibrillation energy requirements in humans has not been well studied. Sotalol (in the d,l racemic form) is an antiarrhythmic with beta-blocking and cardiac refractoriness prolonging effects. The d-isomer of sotalol is largely devoid of beta-blocking effects; both forms decrease defibrillation energy requirements in animals. We hypothesized that d-sotalol would decrease defibrillation voltage and energy requirements in humans.

METHODS AND RESULTS

Fifteen patients undergoing implanted cardioverter defibrillator implantation were studied before and 20 minutes after d-sotalol infusion (2 mg/kg IV in 15 min, followed by 1 mg/kg per hour). The estimated energy (E50) and voltage (V50) for 50% success in defibrillation (estimated from two successive defibrillation "threshold" measurements), ventricular effective refractory period, monophasic action potential duration, and mean cycle length of ventricular fibrillation were measured, along with heart rate, blood pressure, and plasma concentration of d-sotalol. There was a significant decrease in defibrillation energy (E50 = 12.4 +/- 5.0 J before and 8.4 +/- 4.0 J after d-sotalol, P < 0.003) and voltage (V50 = 440 +/- 77 V before and 354 +/- 93 V after d-sotalol, P < 0.001). Consistent with the Class III effect of d-sotalol, ventricular effective refractory period increased from 284 +/- 21 to 330 +/- 24 msec (P < 0.001), and action potential duration was prolonged from 296 +/- 28 to 340 +/- 22 msec (P < 0.001). Following d-sotalol, there was a tendency for induced tachyarrhythmia to self-terminate (23/102 episodes before vs 74/150 after sotalol, P < 0.001), and ventricular fibrillation cycle length was increased from 216 +/- 20 msec before to 274 +/- 23 msec (P < 0.001) after d-sotalol, despite the persistence of a rapid, disorganized rhythm of the surface ECG. No patient suffered adverse effects.

CONCLUSIONS

d-Sotalol lowers defibrillation energy by a mean 32% +/- 27% at concentrations producing a 16% +/- 7% increase in ventricular effective refractory period. Along with its other antiarrhythmic effects, d-sotalol may increase the safety margin for defibrillation or allow lower programmed energies in patients with implanted defibrillators.

Hyperaldosteronism and sudden cardiac death

From a database of 130 implantable cardiac defibrillator recipients, 2 patients (1.5%) with sudden cardiac death as a presenting symptom, leading to diagnosis of primary hyperaldosteronism, are described. This is a newly described cause of sudden cardiac death, possibly more frequent than suspected, which should be considered in patients with malignant arrhythmias and hypokalemia.

Management of intracardiac device recalls: a consensus conference

The incidence of cardiac device recalls seems to be increasing, due in part to increasing complexity, but also to greater public awareness and regulatory overview. Manufacturers are responsible for postmarket surveillance of their implanted products; evidence for poor performance is usually evaluated by a physician advisory committee, and unacceptable failure rates or modes prompt the issuance of a recall. A consensus conference was held March 6, 1995 in Toronto, Ontario to discuss the management of cardiac device recalls after the provincial Ministry of Health issued unique guidelines regarding a recent lead problem. Various stakeholders expressed their views and concerns: the federal regulatory body, the provincial Ministry of Health and hospital association, manufacturers, hospital legal counsel, patient and media advocates and physicians from the United Kingdom, the United States and Canada. Specific recommendations included the establishment of a national (or regional) pacemaker (device/lead) registry interposed between the manufacturer and the federal authority; the creation of a recall task force to deal with specific problems distinct from the manufacturers' physician advisory committee; emphasis on patient responsibility for obtaining regular follow-up and maintaining contact by a pacemaker passport system as exists in Europe; and the fair assignment of costs involved in a recall with specific emphasis on appropriate compensation for physicians and clinic personnel.

Management of intracardiac device recalls: a consensus conference. Participants of the Consensus Conference. North American Society of Cardiac Pacing and Electrophysiology (NASPE)

The incidence of cardiac device recalls seems to be increasing, in part due to increasing complexity, but also due to greater public awareness and regulatory overview. Manufacturers are responsible for postmarket surveillance of their implanted products; evidence for poor performance is usually evaluated by a Physician Advisory Committee (PAC) and unacceptable failure rates or modes prompt the issuance of a recall. A Consensus Conference was held March 6, 1995, in Toronto, Ontario, to discuss the management of cardiac device recalls after the provincial Ministry of Health issued unique guidelines regarding a recent lead problem. Various stakeholders expressed their views and concerns: the federal regulatory body, the provincial Ministry of Health and hospital association, manufacturers, hospital legal counsel, patient and media advocates, and physicians from the United Kingdom, the United States, and Canada. Specific recommendations included: the establishment of a National (or regional) Pacemaker (device/lead) Registry interposed between the manufacturer and the federal authority; the creation of a Recall Task Force (RTF) to deal with specific problems distinct from the manufacturers' PAC; emphasis on patient responsibility for obtaining regular follow-up and maintaining contact by a pacemaker passport system as exists in Europe; and the fair assignment of costs involved in a recall with specific emphasis on appropriate compensation for physicians and clinic personnel.

Congenital genitourinary tract abnormalities following cocaine exposure in utero

The purpose of this study was to review the clinical and ultrasound experience of renal tract abnormalities associated with cocaine exposure in utero. We undertook a 3-year chart review of all infants admitted to British Columbia's Children's Hospital neonatal intensive care unit and Sunny Hill Health Centre for Children in order to identify patients with the diagnostic code for maternal drug or substance use. There were 136 neonates with a positive history or urine drug screen. Renal ultrasound scans had been performed on 79 patients. Ultrasound abnormalities were found in 11 patients (14%) and included horseshoe kidney (2), unilateral abnormal small kidney (1), duplex kidney (1), and renal tract dilation (8). Clinical findings were glandular (2) and juxtaglandular (1) hypospadias with chordee. The patients with hypospadias did not have other abnormalities or abnormal renal ultrasound scans. In our population of infants exposed to cocaine in utero we detected an increased incidence of hypospadias and an increased incidence of renal tract abnormalities. We conclude that cocaine exposure in utero may well be a risk factor for renal tract anomalies. However, a larger, longer-term prospective study is necessary before definitive recommendations can be given for routine screening by ultrasound of all infants exposed to cocaine in utero.

Association between QT dispersion and autonomic dysfunction in patients with diabetes mellitus

OBJECTIVES

We hypothesized that QT dispersion would be increased in patients with diabetes mellitus and autonomic dysfunction and that QT dispersion would be related to abnormal iodine-123 (I-123) metaiodobenzylguanidine (MIBG) uptake.

BACKGROUND

Patients with diabetes mellitus and autonomic dysfunction have an increased incidence of sudden death. This event may be due to a sympathetic imbalance causing disturbances of repolarization. QT dispersion has recently been demonstrated to reflect dispersion of ventricular refractoriness and is a marker of arrhythmogenic potential. Uptake of I-123 MIBG is a reliable measure of whether the tissue examined receives sympathetic neuronal innervation.

METHODS

Fifty-one diabetic patients and 11 normal subjects were studied. All patients had clinical evaluation for autonomic dysfunction (defined as at least two abnormal heart rate and blood pressure responses to five validated tests). Rest 12-lead electrocardiograms were recorded for measurement of QT dispersion, defined as the longest QT interval minus the shortest QT interval, and corrected for heart rate using Bazett's formula. Visual and quantitative measurements of I-123 MIBG uptake were performed using I-123 MIBG, and technetium-99m sestamibi uptake was used to assess perfusion.

RESULTS

Thirty-five diabetic patients had autonomic dysfunction. Corrected QT dispersion was significantly greater in the patients than in the normal subjects (p = 0.02). The I-123 MIBG scores were also significantly greater in patients with than without autonomic dysfunction (p = 0.0004) and in normal subjects (p = 0.008). There was no correlation between QT dispersion and I-123 MIBG uptake score (r = 0.006, p = 0.97).

CONCLUSIONS

Diabetic patients with autonomic dysfunction have increased QT dispersion and larger I-123 MIBG uptake defects. This finding suggests that such patients have a greater inhomogeneity of repolarization. The lack of correlation between QT dispersion and I-123 MIBG uptake suggests that these abnormalities are mediated by different mechanisms.

Conflicting Objectives for Rural Local Government: Service Provision to Exurban Communities in Israel

The delivery of public services in rural areas is a problem encountered not only by declining and peripheral areas but also by newly founded exurban communities. The problems of small size are exacerbated by the demand within these communities for high levels and a high quality of service provision. The existing local government network in these rural and rurban areas is unable to cope with the increased demand emanating from these new communities. This is particularly problematic in Israel, where the rural system of local government, the regional councils, have traditionally fulfilled the role of providing services to agricultural and cooperative communities. In this paper the nature of the service demands made by new exurban communities in Israel, the problems encountered by the regional councils in providing these same services, and the tensions which result from this lack of compatibility are discussed. Proposed functional solutions are presented and compared, ranging from minor modifications to the existing system of rural local government to those which require a change in the formal municipal status of the exurban communities.

Characterization of the murine mu opioid receptor gene

The analgesic and addictive properties of morphine and other opioid drugs are thought to result from their interaction with mu opioid receptors. Using a delta opioid receptor cDNA as a probe, we have isolated a murine mu opioid receptor cDNA clone (mMOR). Stable expression of mMOR in Chinese hamster ovary cells conferred high binding affinity for mu receptor ligands including morphine and [D-Ala2,N-methyl-Phe4,Gly5-ol]-enkephalin and low affinity for delta and kappa preferring ligands. Treatment of these cell lines with morphine and other mu agonists inhibited forskolin-induced cAMP accumulation, demonstrating a functional coupling of mMOR to the inhibition of adenylate cyclase. The predicted amino acid sequence of mMOR shares approximately 55% overall amino acid identity with the delta receptor and approximately 97% identity with the recently reported rat mu opioid receptor. Expression of the mu receptor in mouse brain as revealed by in situ hybridization parallels the reported pattern of distribution of mu-selective ligand binding sites. Chromosomal localization (to mouse chromosome 10) and Southern analysis are consistent with a single mu opioid receptor gene in the mouse genome, suggesting that the various pharmacologically distinct forms of the mu receptor arise from alternative splicing, post-translational events, or from a highly divergent gene(s).