Acute procedural characteristics, efficacy, and safety of a novel cryoballoon for the treatment of paroxysmal atrial fibrillation: Results from the POLAR-ICE study

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Boston Scientific

Background/Introduction

Pulmonary vein isolation (PVI) using a cryoballoon is well-established for the treatment of paroxysmal atrial fibrillation (PAF). Initial experience with a novel cryoballoon (CB) with a stable low balloon pressure (POLARx, Boston Scientific) has demonstrated acute procedural safety and efficacy in de novo PVI procedures in patients with paroxysmal AF. However, to date, there is limited multicenter data on real world acute outcomes and procedural characteristics with this novel cryoballoon.

Purpose

The purpose of POLAR ICE was to provide real-world data on the acute and chronic outcomes of cryoballoon ablation with POLARx for the treatment of PAF. Here we report on the initial acute outcomes up to 3 months including procedural efficacy, safety, and biophysical parameters.

Methods

POLAR ICE, a prospective, non-randomized, multicenter (international) registry (NCT04250714), enrolled 400 patients across 19 centers, between Aug 2020 and May 2021. This study included any patients indicated for treatment of PAF with the POLARx cryoablation system. The study protocol did not mandate any specific cryodosing regimen, this was left to the operator. Procedural characteristics, such as time to isolation (TTI), cryoablations per pulmonary vein, balloon nadir temperature, and occlusion grade were recorded. PVI was confirmed with entrance block testing.

Results

Complete PVI was achieved in 96.1% of PVs (1437/1496). Procedure and fluoroscopy times were 69.0±25.2 min and 15.8±10.0 min, respectively. Left atrial dwell time was 47.3±18.8 min. The cryoablation characteristics by vein are shown in the Table 1. An average of 4.9±1.8 ablations were performed per patient (1.3±0.7 per vein). Grade 3 or 4 occlusion was achieved in 98.1% of PVs reported. Electrical isolation was achieved with an average TTI of 50±33.8s and in 81.4% of PVs isolation required only a single cryoablation. Nadir temperatures across all pulmonary veins averaged -56.3± 6.5C. Time to -40C was 32.9±11s and Time to Thaw (0C) was 19.5±6.7s across all veins. PVI was performed on atypical anatomies (12 LCPV, 7 RMPV, & 3 RCPV) in 19 pts. Serious adverse events included phrenic nerve palsy (0.5%), tamponade (0.5%), AV block (0.3%), stroke (0.3%), and transient ischemic attack (0.3%).

Conclusions

Real world usage data on the novel CB suggests that this device is safe and effective, with a PV isolation success rate of 96.2% and 81.4% of PVs isolated with a single cryoablation. These data are in keeping with reports on other cryoballon systems and have markedly shorter procedure times than have been previously reported on this cryoballon.

Identifying predictive risk factors for permanent pacemaker implantation up to 30 days post-TAVI

Background

Conduction system abnormalities, including AV block, are amongst the most common complications of transcatheter aortic valve implantation (TAVI). Post-TAVI high degree AV block necessitates permanent pacemaker (PPM) implantation.

Purpose

To assess the ability of standardly available pre-, intra- and post-TAVI factors to predict PPM implantation within 30-days post procedure.

Methods

Demographic and clinical (pre-, intra-, and post-procedural) data including ECG parameters were collected from all patients who underwent TAVI at our centre from August 2017 to November 2020. Patients with pre-existing PPM were excluded from the study. Predictive factors were selected through univariate analysis, and selected characteristics were incorporated into a multivariate binomial logistic regression model, in order to create a 30-day PPM risk-prediction model. The Akaike information criterion (AIC) and area under receiver operating curve (AUC/C-statistic) were used to assess discriminative performance.

Results

In total, data from a total of 446 patients were analysed. Of these, 40 (8.97%) received PPM implantation within 30 days of the procedure. The mean age of the patients was 81.5 (±7.3 SD) years; 99 (22.2%) had pre-existing first degree AV block, 55 (12.3%) had pre-existing left bundle branch block (LBBB) and 50 (11.2%) had pre-existing right bundle branch block (RBBB). Intra-procedurally 40 (9.0%) developed LBBB, 21 (4.7%) developed 3rd degree AV block, and 95 (21.3%) patients required temporary pacing wire (TPW) pacing. Post-procedurally, 138 (30.9%) exhibited AV block, 107 (24.0%) LBBB and 50 (11.2%) RBBB.

The following factors met significance at multivariate logistic regression analysis: pre-TAVI RBBB (OR 6.62 [95% CI, 1.37–36.51]), intra-TAVI 3rd degree AV block (OR 12.80 [95% CI, 3.44–53.34]), intra-TAVI LBBB (OR 4.02 [95% CI, 1.28–12.53]), use of TPW pacing (OR 8.58 [95% CI, 3.19–25.12]) and post-TAVI LBBB (OR 7.84 [95% CI, 2.75–24.46]) (Table).

Finally, variables were incorporated into a multivariate logistic regression model with the outcome variable of 30-day PPM implantation (Figure 1a). A model incorporating five factors (pre-TAVI RBBB, intra-TAVI 3rd degree AV block, intra-TAVI LBBB, use of TPW pacing and post-TAVI LBBB) demonstrated excellent discriminative ability (accuracy 0.925 and an AUC of 0.952) at predicting PPM implantation (Figure 1b).

Conclusions

Following variable selection, the best performing model incorporated five factors including pre-TAVI RBBB, intra-TAVI AV block (3rd degree), intra-TAVI LBBB, use of TPW pacing and post-TAVI LBBB. We aim to validate this model using an external cohort.

Funding Acknowledgement

Type of funding sources: None. Table 1Figure 1

Prevalence and clinical impact of atrioventricular conduction disease in patients with idiopathic pulmonary arterial hypertension

Background

Although bradycardia-related sudden death is common in patients with idiopathic pulmonary arterial hypertension (IPAH), the prevalence and prognostic significance of atrioventricular (AV) conduction disease in this patient group is not well-established.

Objectives

– Determine the prevalence of AV conduction disorders in patients with IPAH

– Investigate the relationship between AV block and functional outcomes and mortality.

Method

12-lead electrocardiograms (ECGs) of patients with IPAH were analysed. Patients were categorised according to the presence or absence of AV block. Demographic, pulmonary haemodynamic, cardiac structural characteristics and expression of genes associated with cardiac conduction were compared and functional and mortality outcomes analysed between groups.

Student's t-tests and χ2 tests were used to compare data. Survival was estimated using Kaplan-Meier analyses. Initial exploratory covariates were included in a univariate analysis and those terms with P-value of <0.1 were then used to generate a Cox proportional-hazards multivariate model.

Results

135 IPAH patients (mean age 55±16 years, 28.1% male) were eligible for analysis. Median follow up was 9 years (interquartile range 4–14 years).

AV block was seen in 34.8% of patients with IPAH compared to 10.8% of matched comparators (p<0.001), drawn from patients attending hospital for non-PAH related reasons.

IPAH patients with conduction disease were more likely to be older (59±16 vs 53±17 years, p=0.038). AV block was associated with more severe right ventricular (RV) basal dilatation (5.1±1.0 vs 4.3±0.7cm, p=0.013) and worse RV function (fractional area change 26±9% vs 31±9%, p=0.14). Pulmonary haemodynamics, right atrial size and resting and exertional oxygen saturations were not significantly different. Expression of HCN1, HCN2, SCN1B, SCN5A, CAV1, and KCN2 genes in peripheral blood from a subcohort was similar between those with and without AV block.

Lower 6 minute walk distances (344±153 vs 408±140m, p=0.035) and worse CAMPHOR scores across all 3 domains were seen in those with AV block (figure 1), and mortality was significantly higher (36.2 vs 13.6%, p=0.002) (figure 2). On multivariate analysis the presence of bundle branch block (BBB) was independently associated with a 2.1-fold increased risk of death (95% CI 1.89–4.85, p=0.045).

Conclusions

AV conduction disorders are more prevalent in IPAH than the general population, and are associated with worse prognosis and functional status. Prospective study is required to validate this finding.

In our cohort AV block could not be explained by hypoxia, differences in pulmonary haemodynamics nor, in a small subgroup, by differential expression of specific transmembrane ion channels implicated in cardiac conduction. More detailed investigation into causal mechanisms of AV block in IPAH could establish whether improved prognosis could be achieved by treatment of AV block.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

The role of marshall bundle epicardial connections in atrial tachycardias after atrial fibrillation ablation

Funding Acknowledgements

Type of funding sources: None.

Background

Atrial tachycardias (ATs) are often seen in the context of AF ablation.

Objectives

We evaluated the role of the Marshall bundle (MB) network in left atrial (LA) ATs using high-density high-spatial resolution 3D mapping.

Methods

199 post-AF ablation LA tachycardias were mapped in 140 consecutive patients (112 (80%) males, mean age: 61.8 years); 133 (66.8%) were macro-reentrant and 66 (33.2%) were scar-related re-entry. MB-dependent perimitral AT (PMAT) was diagnosed where the difference between the post pacing interval and the tachycardia cycle length (PPI-TCL) was <20ms in parts of the expected MB-dependent perimitral circuit (within the VOM, the ridge between the left pulmonary veins and LA appendage (LAA), the anterior LA and between 6- and 11-o’clock of the mitral annulus) and the PPI-TCL was >20ms in areas bypassed by the VOM (the distal coronary sinus (CS), the posterior LA and the mitral isthmus). MB-related re-entry was diagnosed by PPI-TCL <20ms at the left lateral ridge, posterior base of LAA, inferolateral LA or VOM ostium; and PPI-TCL >20ms in the septal annulus. Typically, in MB-dependent localized re-entry, the earliest activation was found along the MB-LA endocardial connection or MB-CS epicardial connection. 

Results

The MB network was found to participate in 60 (30.2%) re-entrant ATs, 31 PMATs and 29 localized re-entries. High-frequency multiphasic fragmented electrograms with long duration were often recorded endocardially or epicardially at the MB-LA or MB-CS connections. The amplitude and duration of these signals were 0.5 ± 0.79 mV and 65 ± 40 ms for MB-PMATs and 0.26 ± 0.28mV and 122 ± 67 ms for MB-localized re-entries. Unipolar EGMs at the site of endocardial-epicardial breakthrough had a rS pattern in all MB-related ATs. Of 60 MB-related ATs, 49 (81.6%) terminated with RF ablation, 44 (73.3%) at the MB-LA junction and 5 (8.3%) at the MB-CS junction, while 9 (15%) terminated after 2.5-5 cc of alcohol infusion inside the vein of Marshall (VOM). Of the 31 MB-related macroreentrant ATs, 17 (54.8%) terminated at the MB-LA junction, 5 (16.1%) at the MB-CS junction and 7 (22.6%) with alcohol infusion inside the VOM. Two macroreentries (6.5%) using the MB did not terminate with RF energy either endocardially at the MB-LA junction or epicardially at the MB-CS junction, and we were unable to identify or cannulate the VOM for ethanol infusion. Of the 29 localized re-entrant ATs using the MB, 27 (93.1%) terminated at the MB-LA junction, none terminated at the MB-CS junction and 2 (6.9%) terminated after alcohol infusion. After a mean follow up of 12 months, only 4 patients (6.7%) had AT recurrence.

Conclusions

MB re-entrant ATs accounted for up to 29% of the left ATs after AF ablation. Ablation of the MB-LA or CS-MB connections or alcohol infusion inside the VOM is required to treat these arrhythmias. Abstract Figure.

P1000Aetiology and efficacy of atrial fibrillation ablation in young adults

Introduction

Little is known regarding the aetiology or outcome of atrial fibrillation (AF) occurring in young adults. This retrospective analysis was performed to explore the demographics and efficacy of AF ablation in this population.

Methods

Patients were included who had undergone ≥1 AF ablation under the age of 40 between 2006-2018. Recurrence was defined as return of either documented AF or previous symptoms for >30s following a 3-month blanking period. Initial exploratory co-variates were included in a univariate analysis and those terms with P-value of <0.1 were then used to generate a Cox proportional-hazards multivariate model.

Results

124 patients (33.6 ± 4.7 yrs, 77% men), initially presenting with paroxysmal AF (pAF; n = 97) or persistent AF (n = 27), underwent 175 AF ablation procedures. 22.6% (n = 28) also had atrial flutter. Time from symptom onset to first ablation was 50.7 ± 46.2 months. Relevant cardiovascular-related demographics were analysed: hypertension in 8.9% (n = 11); diabetes in 1.6% (n = 2); positive family history of AF in 12.9% (n = 16); and family history of sudden cardiac death in 2.4% (n = 3). Mean CHA2DS2-VASc score was 0.35. Of those patients with documented echocardiogram imaging (n = 91), 26.4% (n = 24) had LA dilatation and 6.6% (n = 6) had LV dysfunction. Patients with LA dilatation underwent more ablations (2.3 ± 0.3) compared to controls (1.5 ± 0.1; p < 0.001).

Ablation strategy was pulmonary vein isolation (PVI) only in 67.2% (n = 119), with additional ablation in the remaining: roof line in 18.9% (n = 33); cavotricuspid isthmus line in 13.1% (n = 23); mitral isthmus line in 2.3% (n = 4); superior vena cava isolation in 2.3% (n = 4); complex fractionated atrial electrograms in 14.9% (n = 26). Mean procedure time was 155 ± 41 min, mean ablation time was 1657 ± 991 s and mean fluoroscopy time was 32.6 ± 23.4 min. General anaesthesia was used in 43.4% (n = 76). Complications included femoral haematoma (n = 2), tamponade (n = 1) and pulmonary vein stenosis (n = 2).

90 days of follow-up was available for 137 procedures performed for pAF (n = 105) and persistent AF (n = 32). For pAF, overall recurrence was 61.9% for first ablations and 62.9% overall. Recurrence was 56.3% for persistent AF.

Factors significantly associated with increased AF recurrence in univariate analysis were

male gender (hazard ratio (HR) 2.3, 95% confidence interval (CI): 1.2-4.4, p = 0.011), hypertension (HR 0.5, CI: 0.2-1.1, p = 0.067), family history of sudden cardiac death (HR 6.8, CI: 1.6-29.0 , p = 0.010) and enlarged LA size (HR 2.2, CI: 1.3-3.6, p = 0.003). In multivariate analysis, the only significant predictor of poor outcome was enlarged LA size (HR 2.0, 95% CI: 1.2-3.5, p = 0.011).

Conclusions

Young patients with AF may have structurally abnormal hearts, and therefore do not only present with lone AF. LA size may be used as a predictor for success. Surveillance imaging may be useful to detect future structural change, which will be the subject of future prospective studies.

Abstract Figure. AF ablation recurrence in young adults

P1381Improved outcome in ablation of ventricular tachycardia in patients with structural heart disease under general anaesthetic

Background

Catheter ablation is an important adjunct to device implantation for secondary prevention of ventricular tachycardia (VT). However, several factors may influence the success of ablations in terms of long-term freedom from VT recurrence. A thus far little examined factor is the use of general anaesthetic (GA) versus conscious sedation during the procedure, which has been shown to improve outcomes in persistent atrial fibrillation (AF) ablation.

Methods

Patients with structural heart disease VT undergoing ablations from January 2015 to March 2019 were retrospectively followed up at a single centre. End points were recurrent VT or device therapy (shock or anti-tachycardia pacing) at one year. Hazard ratios (HR) were generated using a multivariate Cox-regression proportional hazards model including variables of age at ablation, sex, amiodarone use at time of ablation, scar age, left ventricular ejection fraction, use of GA, and diagnosis of: diabetes mellitus (DM), hypertension (HTN), renal impairment or AF.

Results

79 patients (74 male, mean age 68.2+/- 10.3 years) were included. A substrate-based strategy of late potential ablation was employed. 69 had ischaemic and 10 had non-ischaemic cardiomyopathy. Mean scar age was 13.8 +/- 9.8 years; EF was 40-50% in 27 patients, 30-40% in 26 and < 30% in 26. 37 patients had implantable cardioverter defibrillators and 30 had cardiac resynchronisation therapy (CRT) defibrillator devices, 1 had a CRT- pacemaker device and 4 had dual chamber pacemakers. Comorbidities were: DM (16), HTN (31), renal impairment (13), AF (31). 62 patients (79.5%) were on amiodarone at the time of ablation. Mean procedure duration was 234.8 +/- 44.5 min and mean radiofrequency energy application time was 2247 +/- 862 s. 61 were first procedures and 18 were repeat procedures. One patient suffered a complication of groin haematoma. 62 patients (78.5%) underwent VT ablation under GA and 17 (21.5%) under sedation of midazolam and fentanyl. Patient characteristics did not differ between groups. Significant factors which increased freedom from VT recurrence or device therapy were HTN (88.9% vs 59.4%, HR 0.72, 95% confidence interval (CI): 0.007-0.75, p= 0.028), amiodarone treatment (50.0% vs 76.3%, HR 0.036, 95% CI: 0.003-0.404, p = 0.036) and ablation under GA rather than sedation (50.0% vs 75.0%, HR 0.055, 95% CI: 0.006-0.495, p = 0.01) (Fig 1).

Conclusions

In patients with structural heart disease undergoing VT ablation, outcomes are improved with the use of GA over conscious sedation.

Abstract Figure 1

P6586Brugada syndrome risk stratification - Evaluation of clinical and ECG risk markers in a multicenter international primary prevention cohort

Background

Risk stratification for sudden cardiac death (SCD) in Brugada syndrome (BrS) is a significant challenge.

Purpose

To evaluate the importance of clinical and ECG factors in the likelihood of developing significant ventricular arrhythmias (VAs)/SCD in BrS patients.

Methods

VA occurrence during follow-up were assessed and the role of 16 proposed clinical or ECG risk markers evaluated in a multicenter international study of BrS patients and no history of cardiac arrest. Markers with predictive power were identified and incorporated into a risk score model.

Results

Across 15 international centers, 1084 patients were included. During a follow-up of 5.3 years (IQR 2.7–9.0 years)- 110 patients had VA occurrence (10.1%) with an annual event rate of 1.7% (95% CI 1.4–2.0). Of the 16 proposed risk factors, diagnosis by family screening of sudden cardiac death (HR 4.65; p<0.001), probable arrhythmia related syncope (HR 3.88, p<0.001), type 1 spontaneous ECG (HR 3.56; p<0.001), Early Repolarisation (HR 3.15; p<0.001) and type 1 Brugada pattern in peripheral leads (HR 2.42; p<0.001) were associated with a higher VA occurrence risk during follow-up. These 5 variables were incorporated into a risk score model whereby each variable was allocated a point score based on the variable's predictive strength. The total points obtained from the model for a patient could then be translated into the predicted VA occurrence risk during follow-up (Figure 1). The model showed a sensitivity of 63.5% (95% CI 50.0–76.9) and specificity of 84.2% (95% CI 81.1–87.1) in predicting VA occurrence at 5-years follow-up. The model showed a greater discriminative power compared to an existing model (AUC 0.83 vs. 0.71; p<0.001).

Figure 1

Conclusions

This multicenter study with longest reported follow-up to date identified 5 risk markers for VA occurrence. Utilizing these markers in a risk score model can aid BrS risk stratification to enable individualized risk prediction and ICD prescription.

Phenotype, treatment practice and outcome in the cobalamin-dependent remethylation disorders and MTHFR deficiency: Data from the E-HOD registry

AIM

To explore the clinical presentation, course, treatment and impact of early treatment in patients with remethylation disorders from the European Network and Registry for Homocystinurias and Methylation Defects (E-HOD) international web-based registry.

RESULTS

This review comprises 238 patients (cobalamin C defect n = 161; methylenetetrahydrofolate reductase deficiency n = 50; cobalamin G defect n = 11; cobalamin E defect n = 10; cobalamin D defect n = 5; and cobalamin J defect n = 1) from 47 centres for whom the E-HOD registry includes, as a minimum, data on medical history and enrolment visit. The duration of observation was 127 patient years. In 181 clinically diagnosed patients, the median age at presentation was 30 days (range 1 day to 42 years) and the median age at diagnosis was 3.7 months (range 3 days to 56 years). Seventy-five percent of pre-clinically diagnosed patients with cobalamin C disease became symptomatic within the first 15 days of life. Total homocysteine (tHcy), amino acids and urinary methylmalonic acid (MMA) were the most frequently assessed disease markers; confirmatory diagnostics were mainly molecular genetic studies. Remethylation disorders are multisystem diseases dominated by neurological and eye disease and failure to thrive. In this cohort, mortality, thromboembolic, psychiatric and renal disease were rarer than reported elsewhere. Early treatment correlates with lower overall morbidity but is less effective in preventing eye disease and cognitive impairment. The wide variation in treatment hampers the evaluation of particular therapeutic modalities.

CONCLUSION

Treatment improves the clinical course of remethylation disorders and reduces morbidity, especially if started early, but neurocognitive and eye symptoms are less responsive. Current treatment is highly variable. This study has the inevitable limitations of a retrospective, registry-based design.

Assessment of a conduction-repolarisation metric to predict Arrhythmogenesis in right ventricular disorders

BACKGROUND

The re-entry vulnerability index (RVI) is a recently proposed activation-repolarization metric designed to quantify tissue susceptibility to re-entry. This study aimed to test feasibility of an RVI-based algorithm to predict the earliest endocardial activation site of ventricular tachycardia (VT) during electrophysiological studies and occurrence of haemodynamically significant ventricular arrhythmias in follow-up.

METHODS

Patients with Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) (n = 11), Brugada Syndrome (BrS) (n = 13) and focal RV outflow tract VT (n = 9) underwent programmed stimulation with unipolar electrograms recorded from a non-contact array in the RV.

RESULTS

Lowest values of RVI co-localised with VT earliest activation site in ARVC/BrS but not in focal VT. The distance between region of lowest RVI and site of VT earliest site (Dmin) was lower in ARVC/BrS than in focal VT (6.8 ± 6.7 mm vs 26.9 ± 13.3 mm, p = 0.005). ARVC/BrS patients with inducible VT had lower Global-RVI (RVIG) than those who were non-inducible (-54.9 ± 13.0 ms vs -35.9 ± 8.6 ms, p = 0.005) or those with focal VT (-30.6 ± 11.5 ms, p = 0.001). Patients were followed up for 112 ± 19 months. Those with clinical VT events had lower Global-RVI than both ARVC and BrS patients without VT (-54.5 ± 13.5 ms vs -36.2 ± 8.8 ms, p = 0.007) and focal VT patients (-30.6 ± 11.5 ms, p = 0.002).

CONCLUSIONS

RVI reliably identifies the earliest RV endocardial activation site of VT in BrS and ARVC but not focal ventricular arrhythmias and predicts the incidence of haemodynamically significant arrhythmias. Therefore, RVI may be of value in predicting VT exit sites and hence targeting of re-entrant arrhythmias.

Papillary Adenocarcinoma of the Extrahepatic Bile Duct in a Holstein Cow

A 15-year-old female Holstein cow was presented with a history of anorexia and weight loss. Abnormal physical examination findings included poor body condition, dehydration, icterus, and photodermatitis on nonpigmented areas of the skin of the dorsum. At necropsy, the common bile duct was greatly enlarged, with thickened walls, and tightly adhered to the hepatic capsular surface and serosa of adjacent loops of the small intestine. Two sessile, yellowish, friable, well-circumscribed, cauliflower-like, bulging masses (14 and 8 cm in diameter) were attached to the inner surface of the common bile duct blocking its lumen. Microscopically, the tumor was composed of well-differentiated, columnar epithelial cells with oval or round, vesicular, basal nuclei arranged in papillary projections. Periodic acid-Schiff-positive material accumulated in the apical cytoplasm of the neoplastic cells. Immunostaining of the tumor cells was positive for cytokeratin (CK) of wide-spectrum screening and for CK 7. The diagnosis of papillary adenocarcinoma of the extrahepatic bile duct was based on the morphologic features of the neoplasm and evidence of local invasion. To the best of our knowledge, extrahepatic bile duct carcinomas have not been described in cattle.

Transition voltage spectroscopy and the nature of vacuum tunneling

Transition voltage spectroscopy (TVS) has been proposed as a tool to analyze charge transport through molecular junctions. We extend TVS to Au-vacuum-Au junctions and study the distance dependence of the transition voltage V(t)(d) for clean electrodes in cryogenic vacuum. On the one hand, this allows us to provide an important reference for V(t)(d) measurements on molecular junctions. On the other hand, we show that TVS forms a simple and powerful test for vacuum tunneling models.

Regional variations in action potential alternans in isolated murine Scn5a (+/-) hearts during dynamic pacing

AIM

clinical observations suggest that alternans in action potential (AP) characteristics presages breakdown of normal ordered cardiac electrical activity culminating in ventricular arrhythmogenesis. We compared such temporal nonuniformities in monophasic action potential (MAP) waveforms in left (LV) and right ventricular (RV) epicardia and endocardia of Langendorff-perfused murine wild-type (WT), and Scn5a(+/-) hearts modelling Brugada syndrome (BrS) for the first time.

METHODS

a dynamic pacing protocol imposed successively incremented steady pacing rates between 5.5 and 33 Hz. A signal analysis algorithm detected sequences of >10 beats showing alternans. Results were compared before and following the introduction of flecainide (10 microm) and quinidine (5 microm) known to exert pro- and anti-arrhythmic effects in BrS.

RESULTS

sustained and transient amplitude and duration alternans were both frequently followed by ventricular ectopic beats and ventricular tachycardia or fibrillation. Diastolic intervals (DIs) that coincided with onsets of transient (tr) or sustained (ss) alternans in MAP duration (DI*) and amplitude (DI') were determined. Kruskal-Wallis tests followed by Bonferroni-corrected Mann-Whitney U-tests were applied to these DI results sorted by recording site, pharmacological conditions or experimental populations. WT hearts showed no significant heterogeneities in any DI. Untreated Scn5a (+/-) hearts showed earlier onsets of transient but not sustained duration alternans in LV endocardium compared with RV endocardium or LV epicardium. Flecainide administration caused earlier onsets of both transient and sustained duration alternans selectively in the RV epicardium in the Scn5a (+/-) hearts.

CONCLUSION

these findings in a genetic model thus implicate RV epicardial changes in the arrhythmogenicity produced by flecainide challenge in previously asymptomatic clinical BrS.

Mixed lipid aggregates containing gangliosides impose different2H-NMR dynamical parameters on water environment depending on their lipid composition

Water dynamics in samples of ceramide tetrasaccharide (Gg4Cer) vesicles and GM1 ganglioside micelles at 300:1 water/lipid mole ratio were studied by using deuterium nuclear magnetic resonance (2H-NMR). GM1 imposes a different restriction on water dynamics that is insensitive to temperatures either above or below its phase transition temperature or below the freezing point of water. The calculated correlation times are in the range of 10(-10) s, typical of water molecules near to the polar groups. Pure GM1 micelles have two distinct water microenvironments dynamically characterized. Their dynamic parameters remain constant with temperature ranging from -18 to 32 degrees C, but the amount of strongly associated water is modified. By contrast, a mixture of single soluble carbohydrates corresponding to GM1 polar head group does not preserve the dynamic parameters of water hydration when the temperature is varied. Incorporation of cholesterol or lysophosphatidylcholine into GM1 micelles substantially increases the mobility of water molecules compared with that found in pure GM1 micelles. The overall results indicate that both the supramolecular organization and the local surface quality (lipid-lipid interaction) strongly influence the interfacial water mobility and the extent of hydration layers in glycosphingolipid aggregates.

Measuring the incidence of acute myocardial infarction: the problem of possible acute myocardial infarction

Variations in the ratio of "definite" to "possible" myocardial infarction for non-fatal cases were examined in studies that used World Health Organization criteria. There were large variations in this ratio, variations which appeared to be due to differences in the ascertainment of non-fatal cases of "possible" myocardial infarction, which, in turn, contributed to reported differences in the incidence of myocardial infarction. A significant proportion of cases of "possible" myocardial infarction probably do not have ischemic heart disease at all, since, in our data, cases of "possible" myocardial infarction (non-fatal) with a hospital discharge diagnosis of chest pain (undiagnosed) had a risk of death that was no worse than that in the general population. Thus the most reproducible, and possibly most accurate estimates of the incidence of myocardial infarction may come from including only fatal cases of "possible" myocardial infarction with both fatal and non-fatal cases of "definite" myocardial infarction.

Kiss and tell: what do we know about pre- and early adolescent females who report dating? A pilot study

STUDY OBJECTIVE

To evaluate the implications of dating in pre- and early adolescent females.

DESIGN

Cross-sectional survey.

SETTING

Child psychiatry clinic; pediatric clinic; family clinic.

PARTICIPANTS

Pre- and early adolescent females (n = 80) aged 11-14 and their parents.

INTERVENTION

Pre- and early adolescent females aged 11-14 and a parent were recruited during a regular clinic visit. Pre- and early adolescent females completed a survey that included measures of dating; sensation seeking; lifetime individual and peer drug use; Attention Deficit Hyperactive Disorder, Oppositional Defiant Disorder and Conduct Disorder symptoms; and onset of menses. Parents were asked similar questions about their child's dating behaviors and peer relationships.

MAIN OUTCOME MEASURE

Association of early dating with individual and peer drug use, sensation seeking, aggressive behavior, and onset of menses.

RESULTS

In pre- and early adolescent females, dating regularly is associated with nicotine and alcohol use, sensation seeking, and aggressive behavior. Dating regularly is also associated with onset of menses and a younger age of onset of menses in those who had started menstruating. Parents under-report their child's dating practices and associated high-risk behaviors.

CONCLUSION

Early dating is associated with nicotine and alcohol use, sensation seeking, aggressive behavior, and early onset of menses in adolescent females. Questions about early dating are a simple and efficient way to open inquiry of both parents and children about high-risk behaviors in the clinic setting.

Micellar anisometry in lyotropic uniaxial nematic phases studied by transversal NMR relaxation dispersion

A new method, based on the measurement of the (23 )( )Na nuclei spin-spin NMR relaxation times ( T2 ), is proposed to investigate the shape of micelles in lyotropic nematic phases. We investigate the ternary lyotropic mixture of sodium dodecyl sulfate, 1-decanol, and water by using the NMR technique, measuring T2 in the two lyotropic uniaxial nematic phases. The characteristic relaxation time curves of each particular phase are analyzed by considering that they are constituted by a superposition of exponential decays with typical characteristic times: in a sense, a T2 spectroscopy. The analysis of the T2 dispersion profiles in both the uniaxial nematic calamitic and discotic phases indicates that our results can be interpreted in terms of the model of intrinsically biaxial micelles in all the nematic phases.

Conservation of RET proto-oncogene splicing variants and implications for RET isoform function

The RET proto-oncogene encodes a receptor tyrosine kinase required for development of the kidney and neural crest-derived cell types. Alternative splicing of the 3' exons of human RET results in three protein isoforms with distinct C-termini: RET9, RET51, and RET43. These RET isoforms show differential binding to downstream adapter molecules, suggesting they may have distinct signaling functions. We have characterized Ret 3' sequences in mouse and investigated alternative splicing of this region. We found that the organization of Ret 3' sequences is very similar to human RET. The mouse locus also has alternatively spliced C-terminal coding regions, and the sequences corresponding to RET9 and RET51 are highly conserved in both position and sequence with the human locus. Further, we compared the predicted C-terminal amino acids of RET9 and RET51 in seven vertebrate species, and found that they are well conserved. We have identified sequence encoding a putative ret43 isoform in mouse, however the predicted amino acid sequence showed low homology to human RET43. Our data suggest that RET isoforms are evolutionarily highly conserved over a broad range of species, which may indicate that each isoform has a distinct role in normal RET function.

Effects of ethanol intoxication on speech suprasegmentals

The effects of ingesting ethanol have been shown to be somewhat variable in humans. To date, there appear to be but few universals. Yet, the question often arises: is it possible to determine if a person is intoxicated by observing them in some manner? A closely related question is: can speech be used for this purpose and, if so, can the degree of intoxication be determined? One of the many issues associated with these questions involves the relationships between a person's paralinguistic characteristics and the presence and level of inebriation. To this end, young, healthy speakers of both sexes were carefully selected and sorted into roughly equal groups of light, moderate, and heavy drinkers. They were asked to produce four types of utterances during a learning phase, when sober and at four strictly controlled levels of intoxication (three ascending and one descending). The primary motor speech measures employed were speaking fundamental frequency, speech intensity, speaking rate and nonfluencies. Several statistically significant changes were found for increasing intoxication; the primary ones included rises in F0, in task duration and for nonfluencies. Minor gender differences were found but they lacked statistical significance. So did the small differences among the drinking category subgroups and the subject groupings related to levels of perceived intoxication. Finally, although it may be concluded that certain changes in speech suprasegmentals will occur as a function of increasing intoxication, these patterns cannot be viewed as universal since a few subjects (about 20%) exhibited no (or negative) changes.

The effect of hot beverages, cold beverages, and chewing gum on oral temperature

BACKGROUND

A prospective blood donor's oral temperature is affected by external stimuli such as drinking a hot or cold beverage or chewing gum. These stimuli can cause a deferral or an inappropriate acceptance for a certain unknown time.

STUDY DESIGN AND METHODS

Ten volunteer subjects were exposed to each of the three stimuli in separate studies. Oral and tympanic membrane temperatures were taken before exposure, immediately after exposure, and at various times until the subject's temperature returned to baseline.

RESULTS

The drinking of a hot beverage caused an immediate mean temperature elevation of 2.6 degrees F which would lead to deferral for 7 of 10 subjects. All subjects were acceptable for blood donation (temperature <99.6 degrees F) by 5 minutes. A cold beverage lowered the temperature; the temperature in 6 subjects returned to baseline by 10 minutes and that in 4 did so by 30 minutes. Gum chewing caused minimal temperature elevations; only 1 donor's temperature reached 99.6 degrees F, and it was at acceptable levels for blood donation by 5 minutes.

CONCLUSION

Drinking a hot beverage and, to a much lesser degree, gum chewing can lead to a deferral for elevated temperature, but subjects were acceptable by 5 minutes. Cold beverages are of more concern, because they suppress the temperature for a short time and could theoretically lead to acceptance of a febrile, possibly infectious donor.

HealthSense: how changes in sensory physiology, sensory psychology and sociocognitive factors influence food choice

HealthSense is a multi-centre shared cost research project in sensory and consumer sciences. This project was initiated in response to changing population demographics, which predict a significant increase in the older age group. The primary objective of HealthSense is to determine accurately the effects of ageing on the perceptual abilities of the sensory systems, and ultimately how age-related change determines sensory preferences and food choice. The project is carried out by 24 participating institutes located in 10 different European countries. The project is funded by the European Commission Quality of Life Fifth Framework Programme (QLKI-CT-1999-00010).

Alcohol use in adolescent females: correlates with estradiol and testosterone

This study investigated if self-reports of alcohol use correlated with estradiol and testosterone levels in adolescent females. Ninety-four female senior high school student volunteers from 2 schools completed a questionnaire regarding alcohol use. Twenty cc of blood was assayed for estradiol, testosterone, progesterone, and FSH. Total estradiol levels were higher in females who reported current alcohol use (p < or = 0.05), and females with higher levels of both testosterone and estradiol were more likely to be using alcohol currently (p < or = 0.05). Hormonal relationships associated with adolescent alcohol use may be related to future health risks of alcohol use and/or increased risk of alcohol use.

The association of testosterone with nicotine use in young adult females

This pilot laboratory study examined the relationship of testosterone levels, carbon monoxide (CO) levels, current and adolescent nicotine use, and histories of pubertal onset in 30 young adult female smokers. These females had completed questionnaires regarding nicotine use in the 7th through 10th grades, and again at age 21 as part of a cohort study of drug use. In addition, history of pubertal onset was obtained at age 21, as were testosterone and CO levels. Testosterone levels were positively correlated with cigarette use in the last 30 days (P< or =.01), CO levels (P< or =.05), cigarette use reported in the 7th and 10th grades (P< or =.05), and negatively correlated with age of pubertal onset (P< or =.001). The relationship of testosterone to nicotine will be discussed.

The importance of fulfilling unmet needs of rural and urban adolescents with substance abuse

PROBLEM

Because of the negative impact on health of drug and alcohol use, this study examined adolescent needs and substance use.

METHODS

Subjects (N = 191) were adolescents aged 14 to 19 in a rural and an urban high school. A modified version of the Need Subscale from the Addiction Research Center Maturation Scale measured a feeling of satisfaction related to meeting basic needs, and an investigator's prepared questionnaire elicited current use of alcohol, nicotine, and marijuana.

FINDINGS

Individuals with feelings of unmet needs were more likely to be current drinkers. Rural/urban residence was not a significant predictor in a multivariate analysis, but religiosity was.

CONCLUSIONS

A feeling of unmet needs seems to be an important factor in adolescent substance use.

Water decolorization using UV radiation and hydrogen peroxide: a kinetic study

Sometimes, provision of water for domiciliary consumption faces the problem of natural contamination originated by the presence of organic substances such as humic or fulvic acids. Very often, after conventional sanitary treatments this water exhibits a persistent yellowish coloration that affects its use. Moreover, these substances may act as precursors of tri-halomethanes formation during pre-disinfection with chlorine. This paper presents, with a simplified mechanistic approach, the intrinsic reaction kinetics of natural water decolorization employing UV radiation and hydrogen peroxide. The main variables for the model are: contaminant concentration expressed as TOC, hydrogen peroxide concentration and the photon absorption rate.

Production of intoxication states by actors--acoustic and temporal characteristics

This paper is the second of a series; the first has been published (J Forensic Sci, 1998;43:1153-62). The goal in the initial pair of experiments was to determine if speakers (actors) could effectively mimic the speech of intoxicated individuals and also volitionally reduce the degradation to their speech that resulted from severe inebriation. To this end, two highly controlled experiments involving 12 actor-speakers were carried out. It was found that, even when sober, nearly all of them were judged drunker (when pretending) than when they actually were severely intoxicated. In the second experiment, they tried to sound sober when highly intoxicated; here most were judged less inebriated than they were. The goal of this second paper is to identify some of the speech characteristics that allowed the subjects to achieve the cited illusions. The focus here is on four paralinguistic factors: fundamental frequency (F0), speaking rate, vocal intensity, and nonfluency level. For the simulation of intoxication study, it was found that F0 was raised along with increased intoxication but raised even more when this state was feigned. A slowing of speaking rate was associated with increasing intoxication, but this shift also was greater when the speaker simulated intoxication. The most striking contrast was found for the nonfluencies; they were doubled for actual intoxication, but quadrupled when intoxication was simulated. On the other hand, the shifts exhibited by the subjects when they attempted to sound sober were not as clear cut. Indeed, no systematic relationships were found here for either F0 or vocal intensity. Both speaking rate and the number of nonfluencies shifted appropriately, but these changes were not statistically significant. In sum, discernable suprasegmental relationships occurred for both studies (but especially the first); further, it is predicted that useful cues also will be found embedded in the segmentals (the sounds of speech).

Card Perseveration Task performance and post-task feeling states: relationship to drug use in adolescents

This study examined whether performance on the Card Perseveration Task (Card Task) and self-report of feeling state after the task are related to self-report of drug use. The evaluation was of 64 adolescents from an adolescent psychiatric outpatient clinic (40 males, aged 15.5 years, SD = 1.6; 24 females aged 16.9 years, SD = 1.5). Drug use histories were obtained using a substance dependence symptom checklist based on DSM-III-R. The Card Task was administered, and after completion, a Post-Task Self-Report (PTSR) was administered. A factor analysis with varimax rotation grouped the 28 items of the PTSR into Distress, Happy, Satisfied, and Wanting to Win subscales. Correlations of drug use with performance on the Card Task and the PTSR subscales were obtained. Cards Played on the Card Task were correlated with alcohol (cc = .31, p < or = .01); marijuana (cc = .35, p < or = .01) and polydrug (cc = .26, p < or = .05) dependence symptoms. Money Won on the Card Task was correlated negatively with nicotine (cc = -.26, p < or = .05) and marijuana (cc = -.27, p < or = .05) dependence symptoms. The PTSR Distress subscale correlated with nicotine (cc = .49, p < or = .001), alcohol (cc = .37, p < or = .01), marijuana (cc = .39, p < or = .01), and polydrug (cc = .49, p < or = .001) dependence symptoms. These findings provide evidence that both the Card Task and feeling states associated with task performance are related to self-reports of drug use.

Comparative effects of the human protein C activator, Protac, on the activated partial thromboplastin clotting times of plasmas, with special reference to the dog

The commercial snake venom extract, Protac, is a specific activator of the anticoagulant zymogen, protein C (PC) in human plasma. This specific action has led to its use in developing coagulation-based and amidolytic-based assays for the diagnosis of quantitative and/or qualitative PC deficiency states in human beings. The purpose of the present study was to compare the effects of Protac on the activated partial thromboplastin times (APTT) of human, bovine, equine, and canine plasmas in order to determine the potential value of this venom extract as an activator in functional PC assays in these domestic animal species. As expected, Protac significantly prolonged the APTT of normal human plasma, but had no effect on plasma known to be devoid of PC. Clotting times were prolonged by 34%-214% with concentrations of venom activator ranging from 0.1-1.0 U/mL. Under identical conditions, Protac prolonged the APTT of equine plasma by 11%-98% over control times. Even more dramatic was the inhibitory effect of Protac on the clotting of bovine plasma, extending the APTT more than 3-fold at a venom concentration of 0.1 U/mL. At higher venom concentrations, most bovine plasmas remained unclotted after 300 s (control time 34.1 s). Under similar conditions, the canine APTT was unaffected by Protac, even when the venom concentration was increased to 3 U/mL. In order to determine the reason for the lack in response of canine plasma, the concentration of the APTT reagent was altered (decreased), exposure time of the plasma to the Protac was increased from 2 min to 9 min, and the plasma was diluted to assess for the potential existence of plasma PC inhibitors. Protac caused an unexpected shortening of the APTT when the contact activator reagent was diluted. Increasing the exposure time had no effect. Although a slight prolongation of the canine APTT was detected when the plasma was diluted, the presence of strong plasma PC inhibition was considered an unlikely cause of the lack of significant anticoagulant action. The failure of Protac to exert a strong inhibitory effect on the canine APTT, as well as to generate amidolytic activity, suggests that this venom extract does not stimulate the production of activated PC activity in canine plasma. This may result from molecular differences in the canine PC molecule that prevent the formation of the stoichiometric complex of venom extract, APTT reagent, and canine protein, a complex thought to be essential for the PC-activating function of Protac. Protac may be suitable as an activator of PC in bovine and equine plasmas; however, it appears ineffective in generating anticoagulant activity in canine plasma.

Axial length decrease accompanying successful glaucoma filtration surgery

OBJECTIVE

To evaluate change in axial length measurement after successful glaucoma filtering surgery.

DESIGN

Retrospective consecutive case series.

PARTICIPANTS

Sixty-two patients with phakia who underwent primary trabeculectomy.

INTERVENTION

The A-scan biometry of ocular axial length before and after trabeculectomy.

MAIN OUTCOME MEASURES

Changes in ocular axial length measurement after successful trabeculectomy were analyzed.

RESULTS

The mean decrease in axial length measurement was 0.423 mm (range, -2.8 to +0.5 mm). Regression analysis yielded a statistically significant association between decrease in axial length measurement and age (P = 0.0001) and post-trabeculectomy intraocular pressure decrease greater than 30 mmHg (P = 0.01). Analysis of variance revealed a significant association between decrease in axial length measurement and use of antimetabolite (P = 0.005). Pseudophakic axial length measurements increased an average of 0.275 mm compared to the axial length after trabeculectomy and before cataract surgery.

CONCLUSIONS

Axial length measurement decreased in 32 of 62 eyes after successful initial trabeculectomy. A decrease in axial length measurement may have an influence on intraocular lens calculations. Therefore, the authors recommend that an axial length measurement be obtained on phakic eyes before an initial trabeculectomy to reduce the risk of an inaccurate intraocular lens power calculation based on post-trabeculectomy axial length measurements.

Intraoperative MR imaging guidance for intracranial neurosurgery: experience with the first 200 cases

PURPOSE

To review preliminary experience with an open-bore magnetic resonance (MR) imaging system for guidance in intracranial surgical procedures.

MATERIALS AND METHODS

A vertically oriented, open-configuration 0.5-T MR imager was housed in a sterile procedure room. Receive and transmit surface coils were wrapped around the patient's head, and images were displayed on monitors mounted in the gap of the magnet and visible to surgeons. During 2 years, 200 intracranial procedures were performed.

RESULTS

There were 111 craniotomies, 68 biopsies, 12 intracranial cyst evaluations, four subdural drainages, and five transsphenoidal pituitary resections performed with the intraoperative MR unit. In each case, the intraoperative MR system yielded satisfactory results by allowing the radiologist to guide surgeons toward lesions and to assist in treatment. In two patients, hyperacute hemorrhage was noted and removed. The duration of the procedure and the complication rate were similar to those of conventional surgery.

CONCLUSION

Intraoperative MR imaging was successfully implemented for a variety of intracranial procedures and provided continuous visual feedback, which can be helpful in all stages of neurosurgical intervention without affecting the duration of the procedure or the incidence of complications. This system has potential advantages over conventional frame-based and frameless stereotactic procedures with respect to the safety and effectiveness of neurosurgical interventions.

The mechanisms of action of interleukin-1 on rabbit intestinal epithelial cells

Interleukin-1 (IL-1) is an inflammatory mediator that increases Cl- secretion in intestinal epithelial cells. To identify the signal transduction pathway(s) involved in IL-1's action, cells were treated with IL-1 and the levels of cyclooxygenase (COX) enzymes, prostaglandin E2 (PGE2) and phospholipase A2-activating protein (PLAP), and the activity of phospholipase A2 (PLA2) were measured. IL-1 caused concentration- and time-dependent increases in the levels of PLA2 activity, and/or in the levels of PLAP, COX-2 and PGE2. The IL-induced increase in PGE2 levels was biphasic, with the first peak due to the increase in PLAP levels, and the second peak due to the increase in COX-2 levels. This increase in PGE2 levels may provide a mechanism for acute and chronic inflammation in the intestine.

Production of intoxication states by actors: perception by lay listeners

The effects of ingesting ethanol have been shown to be somewhat variable in humans; there appear to be but few universals. Yet, questions about intoxication often are asked by law enforcement personnel (especially relative to DUI), clinicians and various individuals in social settings. A key question: Is it possible to determine if a person is intoxicated by observing them in some manner? A closely associated one: Can speech be used for that purpose? Two of the many issues related to the second of these questions involve the possibility that (1) speakers, especially actors, can effectively mimic the speech of intoxicated individuals, and (2) they may be able to volitionally reduce any speech degradation which results from intoxication. The approach used to test these two questions tasked auditors to determine if these simulations were possible. To this end, young, healthy actors chosen on the basis of a large number of selection criteria were asked to produce several types of controlled utterances (1) during a learning phase, (2) when sober, (3) at three simulated levels of intoxication (mildly, legally and severely drunk), (4) during actual, and parallel, levels of intoxication, and (5) at the highest intoxication level attained but when attempting to sound completely sober. Two aural-perceptual studies were conducted; both involved counterbalanced ABX procedures where each subject was paired with him/herself. Listeners were normally hearing university students drawn from undergraduate phonetics and linguistics courses. In the first study, they rated the actors as being more intoxicated--when they actually were sober but simulating drunkenness--88% more often than when they actually were intoxicated. In the second study, they were judged as sounding less inebriated when attempting to sound sober (than they actually were) 61% of the time. These relationships would appear to impact a number of situations; one of special importance would be the detection of intoxication in motorists.

Gap junctional communication between murine macrophages and intestinal epithelial cell lines

In intestinal inflammation, inflammatory cells infiltrate the submucosa and are found juxtaposed to intestinal epithelial cell (IEC) basolateral membranes and may directly regulate IEC function. In this study we determined whether macrophage (M phi), P388D1 and J774A.1, are coupled by gap junctions to IEC lines, Mode-K and IEC6. Using flow cytometric analysis, we show bi-directional transfer of the fluorescent dye, calcein (700 Da) between IEC and M phi resulting in a 3.5-20-fold increase in recipient cell fluorescence. Homocellular and heterocellular dye transfer between M phi and/or IEC was detected in cocultures of P388D1, J774A.1, Mode-K, IEC6 and CMT93. However, transfer between P388D1 and Mode-K was asymmetrical in that transfer from P388D1 to Mode-K was always more efficient than transfer from Mode-K to P388D1. Dye transfer was strictly dependent on IEC-M phi adhesion which in turn was dependent on the polarity of IEC adhesion molecule expression. Both calcein dye transfer and adhesion were inhibited by the addition of heptanol to cocultures. Furthermore we demonstrate both IEC homocellular, and M phi-IEC heterocellular propagation of calcium waves in response to mechanical stimulation, typical of gap junctional communication. Finally, areas of close membrane apposition were seen in electron micrographs of IEC-M phi cocultures, suggestive of gap junction formation. These data indicate that IEC and M phi are coupled by gap junctions suggesting that gap junctional communication may provide a means by which inflammatory cells might regulate IEC function.

Adhesion and cytosolic dye transfer between macrophages and intestinal epithelial cells

Activated macrophages (M phi) found in the intestinal lesions of patients with inflammatory bowel disease (IBD) secrete many inflammatory mediators which can regulate intestinal epithelial cell (IEC) function. However, little is known about direct M phi-IEC interactions. Two potential mechanisms by which cells may interact are through specific receptor-ligand binding of adhesion molecules, such as integrins or cadherins, and by exchange of cytoplasmic substances through transmembraneous channels called gap junctions. We investigated whether M phi could adhere to epithelial cells in culture and form transmembrane communication channels as defined by dye transfer. Primary cultures of murine M phi and a M phi cell line, P388D1, adhered to Mode-K and IEC6, but not CMT-93 IEC. Antibody blocking studies determined that P388D1-Mode-K binding was partially dependent on beta 2 integrin (CD18) function, Mode-K constitutively expressed CD106 (VCAM-1) and cell associated fibronectin, while P388D1 expressed low levels of CD49d/CD29 (VLA4) but blocking antibodies to these surface molecules did not inhibit P388D1-Mode-K adherence. Transfer of calcein dye from M phi to IEC was quantitated by flow cytometry and was dependent on M phi-IEC adhesion. Dye transfer was concentration dependent in that the fluorescence intensity of Mode-K was proportional to the number of adherent P388D1 cells as well as the dye load of the M phi. These results indicate that M phi interact with IEC by adhesion and possibly through gap junctions and may thus regulate IEC function by direct cell-cell communication.

Caffeine consumption habits do not influence the exercise blood pressure response following caffeine ingestion

BACKGROUND

The purpose of this study was to determine if the BP response during walking following caffeine ingestion differed between those who regularly consume caffeine and those who do not.

METHODS

A double-blind cross-over experimental design was used. Data were collected in a research laboratory with a clinical exercise testing room. Eight regular caffeine users and eight men who did not habitually consume caffeine were studied. Each subject consumed of a beverage once with and once without 4.5 mg caffeine/kg fat-free mass added to the drink. Following consumption each subject walked at three intensities of exercise (30, 50, and 70% of VO2peak). Measures of BP were obtained by the auscultatory technique.

RESULTS

Caffeine consumption resulted in significant increases in both systolic BP and diastolic BP at rest and during exercise. The elevation during exercise was 7-8 mmHg at all three exercise intensities for systolic BP; however, for diastolic BP there was only a significant elevation (4 mmHg) at the highest exercise intensity. No differences were noted between those men who regularly consume and those who regularly abstain from caffeine. There was a wide range in the resting BP response to caffeine (combined SBP and DBP ranged from 10-39 mmHg) suggesting that there are marked differences in sensitivity to caffeine, irrespective of individuals' consumption habits.

CONCLUSIONS

Consideration should be given to caffeine intake prior to exercise in patients for whom an additional increase in BP during exercise would not be desirable.

Discriminative stimulus effects of alcohol in humans

The discriminative stimulus effects of alcohol were examined in 11 healthy moderate alcohol users. Study days occurred 5 days per week for 12-25 total days. Each day, participants completed visual-analog reports of drug effect and drug-discrimination tasks at 30-min intervals for 2.5 h following oral alcohol administration. Participants completed three phases. During the training phase, which occurred on the first 4 study days, participants were trained to discriminate color-coded placebo and alcohol doses (0 vs. 0.45 g per liter of body water (g/lbw)). Participants then completed a control phase, during which accurate drug-discrimination performance was verified. Finally, participants completed a testing phase, during which both training and intermediate doses (0.15 and 0.30 g/lbw) were administered. During the testing phase, 25 and 100% of responses occurred on the alcohol key at the 0- and 0.45-g/lbw doses, respectively, indicating that discrimination responding remained intact. At the low dose (0.15 g/lbw), 25% of the subjects responded on the alcohol key, whereas 75% of the subjects responded on the alcohol key at the moderate dose (0.30 g/lbw), indicating dose-related generalization to the training doses. These results confirm cross-species generality in the discriminative stimulus effects of alcohol, and further establishes the utility of human laboratory drug-discrimination procedures for analysis of the functional effects of alcohol.

Ganglioside hydration study by 2H-NMR: dependence on temperature and water/lipid ratio

Dynamic properties of 2H2O in samples of ganglioside aggregates hydrated at water/lipid ratios ranging from 25:1 to 8000:1 mole/mole were studied by using deuterium nuclear magnetic resonance (2H-NMR). We present a physical model for the interpretation of the measured spin-spin relaxation times (T2). For all the concentrations studied the model provides evidence for the existence of at least two kinds of water environments: one in which the rotational correlation time is in the range of 10(-9) to 10(-8) s, and a second in which it lies between 10(-11) to 10(-10) s. A detailed study on the temperature dependence was performed for two of the concentrations, one corresponding to the hexagonal phase (100:1 mole/mole) and the other involving a micellar phase (200:1 mole/mole). In the 100:1 2H2O/ganglioside molar ratio sample, most of the water is tightly bound to long cylindrical structures. For the 200: 1 sample, there are on average approximately 30 water molecules tightly bound to the polar head group of each ganglioside molecule. The relative number and dynamics of molecules in this environment are essentially insensitive to temperature variations in the range 220-300K The rest of water molecules are also influenced by the aggregate, having a different mobility from that observed in the free liquid state.

Gender differences in adolescent psychiatric outpatient substance use: associated behaviors and feelings

OBJECTIVE

To investigate gender differences in substance use and associated high-risk behaviors and feeling states in 220 adolescent psychiatric outpatients.

METHOD

One hundred seven females and 113 males with a mean age of 15.6 (SD +/- 1.4), seen in a tertiary care center adolescent psychiatry clinic, completed scales tapping substance use and associated feelings and behaviors. Approximately half had used nicotine and alcohol, one third had used marijuana, and 10% reported narcotic use.

RESULTS

Conduct disorder behavior, suicidality, and impulsivity scale scores decreased with age in females while marijuana use, conduct disorder behavior, and Hypophoria scale scores increased with age in males. Alcohol use in males, as contrasted with females, correlated more significantly with other substance use and high-risk behaviors. Suicidality tended to correlate more with polysubstance use in females and with sexual behaviors in females only. Substance use correlated with the Impulsivity and Need scale scores in males and scores on the Sociopathy scale in females.

CONCLUSIONS

Substance use in males correlates with high-risk behaviors and is associated with feelings of impulsivity and need. Substance use correlates with self-destructive behaviors and sociopathic feelings in females. There is evidence of more persistent high-risk behaviors, including substance use, in males than in females.

Stimulation of Rb+ influx by bradykinin through Na+/K+/Cl- cotransport and Na+/K(+)-ATPase in NIH-3T3 fibroblasts

Bradykinin receptor stimulation results in G-protein-coupled phospholipase activation, initiating protein kinase C (PKC) stimulation and cytosolic free Ca2+ concentration ([Ca2+]i) rises as signalling pathways. Using Rb+ as a tracer for K+, we have studied the mechanisms involved in bradykinin-stimulated Rb+ influx in NIH-3T3 fibroblasts. The furosemide-sensitive Na+/K+/Cl- cotransport and the ouabain-sensitive Na+/K(+)-ATPase were both involved in Rb+ influx under resting conditions with a ratio Na+/K+/Cl- cotransport/Na+/K(+)-ATPase (r) = 0.73. Bradykinin stimulated Rb+ influx (+82.6%) through both systems without changing their ratio (r = 0.72). PKC stimulation by a 15-min-treatment with phorbol 12-myristate 13-acetate (PMA) (2x10(-7) M) increased Rb+ influx in resting cells by 75.7% without affecting r (0.75). PKC inhibition by H-7, and PKC down-regulation by 24-h PMA (10(-6) M) treatment decreased the bradykinin-induced stimulation of Rb+ influx (+31% and +14.9% above control, respectively). Both down-regulation and inhibition of PKC dramatically reduced the furosemide-sensitive Na+/K+/Cl- cotransport, as r fell to 0.239 and 0.032 in bradykinin-stimulated cells after H-7 and 24-h PMA treatments, respectively. BAPTA/AM pretreatment (10(-4) M, 60 min), which complexed with [Ca2+]i, not only prevented the bradykinin-induced [Ca2+]i raise, but also partially inhibited bradykinin-induced Rb+ influx stimulation (+39% above control), without modifying r (0.76). We conclude that stimulation of PKC is a major pathway involved in bradykinin stimulation of Rb+ influx in NIH-3T3 fibroblasts, and that rises in [Ca2+]i participate in bradykinin signalling, possibly through PKC activation. Our data also suggest that active PKC is required for basal and bradykinin-stimulated Na+/K+/Cl- cotransport activity in these cells.

In vitro pharmacological effects of S 12370 (2-[4-benzhydryloxypiperidinoethyl]isoxindole; an antibronchoconstrictor agent) in normal and sensitized tissue

The effects of S 12370 (2-[4-benzhydryloxypiperidinoethyl]isoxindole), were studied in vitro. In guinea pig isolated tracheal rings, S 12370 induced a similar competitive inhibition of the contractile responses produced by acetylcholine, histamine and serotonin. However, it did not affect the contractions induced by leukotriene D4 (LTD4), substance P and U 46619, a stable analogue of thromboxane A2. S 12370 induced a concentration dependent inhibition of the cholinergic component of the contraction induced by electrical field stimulation, whereas it did not influence the sustained nonadrenergic noncholinergic (NANC) excitatory response observed in guinea pig isolated bronchi. S 12370 did not influence the relaxations induced by prostaglandin E2, isoprenaline and salbutamol, and did not modify the nonadrenergic noncholinergic inhibitory response induced by electrical field stimulation. In isolated left atria, the negative inotropic effect of acetylcholine was competitively inhibited by S 12370. In binding experiments, S 12370 exhibited similar affinity for M1, M2, M3, M4 muscarinic receptors and also recognized 5-HT2 serotonin and H1 histamine receptor subtypes. In ovalbumin-sensitized animals, the contractile response of isolated tracheal rings produced by exposure to the allergen was not influenced by S 12370. Tracheal rings from sensitized animals preexposed in vitro to the allergen developed a hyporesponsiveness to beta-adrenoceptor stimulation. S 12370 prevented the inhibitory effect caused by ovalbumin immune sensitization in the relaxation to isoprenaline. In rat polymorphonuclear neutrophil (PMN) cells, S 12370 up to 10(-5) M did not inhibit the arachidonic acid metabolism. These results suggest that in guinea pig tracheal smooth muscle, S 12370 is a competitive inhibitor of muscarinic, serotonin and histamine receptors and can modulate the beta-adrenergic dysfunction induced by immune sensitization. S 12370 may present some therapeutic interest in inflammatory airway diseases.