50-W vs 40-W During High-Power Short-Duration Ablation for Paroxysmal Atrial Fibrillation: A Multicenter Prospective Study

BACKGROUND

High-power short-duration (HPSD) radiofrequency ablation of atrial fibrillation (AF) increases first-pass pulmonary vein isolation (PVI) and freedom from atrial arrhythmias while decreasing procedural time. However, the optimal power setting in terms of safety and efficacy has not been determined.

OBJECTIVES

This study compared the procedural characteristics and clinical outcomes of 50-W vs 40-W during HPSD ablation of paroxysmal AF.

METHODS

Patients from the REAL-AF prospective multicenter registry (Real-World Experience of Catheter Ablation for Treatment of Symptomatic Paroxysmal and Persistent Atrial Fibrillation) undergoing HPSD ablation of paroxysmal AF, either using 50-W or 40-W, were included. The primary efficacy outcome was freedom from all-atrial arrhythmias. The primary safety outcome was the occurrence of any procedural complication at 12 months. Secondary outcomes included procedural characteristics, AF-related symptoms, and the occurrence of transient ischemic attack or stroke at 12 months.

RESULTS

A total of 383 patients were included. Freedom from all-atrial arrhythmias at 12 months was 80.7% in the 50-W group and 77.3% in the 40-W group (Log-rank P = 0.387). The primary safety outcome occurred in 3.7% of patients in the 50-W group vs 2.8% in the 40-W group (P = 0.646). The 50-W group had a higher rate of first-pass PVI (82.3% vs 76.2%; P = 0.040) as well as shorter procedural (67 minutes [IQR: 54-87.5 minutes] vs 93 minutes [IQR: 80.5-111 minutes]; P < 0.001) and radiofrequency ablation times (15 minutes [IQR: 11.4-20 minutes] vs 27 minutes [IQR: 21.5-34.6 minutes]; P < 0.001) than the 40-W group.

CONCLUSIONS

There was no significant difference in freedom from all-atrial arrhythmias or procedural safety outcomes between 50-W and 40-W during HPSD ablation of paroxysmal AF. The use of 50-W was associated with a higher rate of first-pass PVI as well as shorter procedural times.

A novel artificial intelligence based algorithm to reduce wearable cardioverter-defibrillator alarms

BACKGROUND

The wearable cardioverter defibrillator (WCD) is an important tool in mitigating sudden cardiac death (SCD). The WCD provides patient alarms for detected arrhythmias or electrical noise/artifact. Some patients experience frequent alarms for artifact. We sought to evaluate the effects of a novel artificial intelligence algorithm to reduce alarms related to electrical noise or artifact (advanced arrhythmia discrimination algorithm, AArD).

METHODS

A retrospective review of a large commercial database of prescribed WCD. Patients prescribed the WCD during the years 2017 (discrimination algorithm, DA group) or during 2019 (advanced arrhythmia discrimination algorithm, AArD) were analyzed. A total of 96,000 patients were sampled, 48,000 in the control group (using standard direct algorithm, DA) and compared to 48,000 in the intervention AArD (4000 per group per month) for 12 months. The AArD further discriminates ECG signals based on a machine-learning algorithm utilizing intensity and frequency beyond the standard DA. Outcomes regarding alarms, arrhythmias, and safety were analyzed.

RESULTS

The AArD algorithm was associated with a significant decrease in frequency of alarms over the course of WCD use; 54% of patients in the AARD versus 27% of DA had 0 alarms (P < .001). In the entire cohort, there was a 56% relative reduction in alarms with the use of AArD. Appropriate arrhythmia treatment time was not significantly different between the groups (44 s DA vs 45 s AArD [p = ns]).

CONCLUSIONS

A novel artificial intelligence algorithm reduces alarms without delaying appropriate therapy for VT/VF. These changes may improve compliance and quality of life in patients with a WCD.

Impact of Median Sternotomy on Safety and Efficacy of the Subcutaneous Implantable Cardioverter Defibrillator

BACKGROUND

Subcutaneous implantable cardioverter defibrillators (S-ICDs) are an attractive alternative to transvenous ICDs among those not requiring pacing. However, the risks of damage to the S-ICD electrode during sternotomy and adverse interactions with sternal wires remain unclear. We sought to determine the rates of damage to the S-ICD lead during sternotomy, inappropriate shocks from electrical noise due to interaction with sternal wires, and failure to terminate spontaneous or induced ventricular arrhythmias.

METHODS

Retrospective, multicenter study of patients undergoing sternotomy before or after S-ICD implantation. Clinical, procedural, and device-related data were collected by each center and analyzed by the coordinating center. These data were compared with a historical control cohort of nonsternotomy patients.

RESULTS

Of 196 identified patients (52±16 years, 47 women), 166 underwent S-ICD implantation after sternotomy and 30 sternotomy after S-ICD. There was no damage to any lead among those who underwent sternotomy after S-ICD. Defibrillation threshold testing was performed in 63% at implant, with 91% first shock success. During a median follow-up of 29 months (range, 1-188), S-ICD first shocks successfully terminated spontaneous ventricular arrhythmias in 31 of 32 patients (97%). Inappropriate shocks occurred in 22 patients, most commonly related to T wave oversensing (n=14). Compared with the nonsternotomy controls, there were no differences in rates of first shock success for induced or spontaneous arrhythmias or rate of inappropriate shocks.

CONCLUSIONS

Sternotomy before or after S-ICD does not confer additional risk relative to a historical control group without sternotomy.

High-Frequency Low-Tidal Volume Ventilation Improves Long-Term Outcomes in AF Ablation: A Multicenter Prospective Study

BACKGROUND

High-frequency, low-tidal-volume (HFLTV) ventilation is a safe and simple strategy to improve catheter stability and first-pass isolation during pulmonary vein (PV) isolation. However, the impact of this technique on long-term clinical outcomes has not been determined.

OBJECTIVES

This study sought to assess acute and long-term outcomes of HFLTV ventilation compared with standard ventilation (SV) during radiofrequency (RF) ablation of paroxysmal atrial fibrillation (PAF).

METHODS

In this prospective multicenter registry (REAL-AF), patients undergoing PAF ablation using either HFLTV or SV were included. The primary outcome was freedom from all-atrial arrhythmia at 12 months. Secondary outcomes included procedural characteristics, AF-related symptoms, and hospitalizations at 12 months.

RESULTS

A total of 661 patients were included. Compared with those in the SV group, patients in the HFLTV group had shorter procedural (66 [IQR: 51-88] minutes vs 80 [IQR: 61-110] minutes; P < 0.001), total RF (13.5 [IQR: 10-19] minutes vs 19.9 [IQR: 14.7-26.9] minutes; P < 0.001), and PV RF (11.1 [IQR: 8.8-14] minutes vs 15.3 [IQR: 12.4-20.4] minutes; P < 0.001) times. First-pass PV isolation was higher in the HFLTV group (66.6% vs 63.8%; P = 0.036). At 12 months, 185 of 216 (85.6%) in the HFLTV group were free from all-atrial arrhythmia, compared with 353 of 445 (79.3%) patients in the SV group (P = 0.041). HLTV was associated with a 6.3% absolute reduction in all-atrial arrhythmia recurrence, lower rate of AF-related symptoms (12.5% vs 18.9%; P = 0.046), and hospitalizations (1.4% vs 4.7%; P = 0.043). There was no significant difference in the rate of complications.

CONCLUSIONS

HFLTV ventilation during catheter ablation of PAF improved freedom from all-atrial arrhythmia recurrence, AF-related symptoms, and AF-related hospitalizations with shorter procedural times.

Performance of the REAL-AF Same-Day Discharge Protocol in Patients Undergoing Catheter Ablation of Atrial Fibrillation

BACKGROUND

Same-day discharge (SDD) after catheter ablation of atrial fibrillation (AF) has been widely adopted. Nevertheless, planned SDD has been performed by using subjective criteria rather than standardized protocols.

OBJECTIVES

The goal of this study was to determine the efficacy and safety of the previously described SDD protocol in a prospective multicenter study.

METHODS

Using the REAL-AF (Real-world Experience of Catheter Ablation for the Treatment of Paroxysmal and Persistent Atrial Fibrillation) SDD protocol eligibility criteria (stable anticoagulation, no bleeding history, left ventricular ejection fraction >40%, no pulmonary disease, no procedures within 60 days, and body mass index <35 kg/m2), operators prospectively determined whether patients undergoing ablation of AF were candidates for SDD (SDD vs non-SDD groups). Successful SDD was achieved if the patient met the protocol discharge criteria. The primary efficacy endpoint was the success rate of SDD. The primary safety endpoints were readmission rates as well as acute and subacute complications. The secondary endpoints included procedural characteristics and freedom from all-atrial arrhythmias.

RESULTS

A total of 2,332 patients were included. The REAL-AF SDD protocol identified 1,982 (85%) patients as potential candidates for SDD. The primary efficacy endpoint was achieved in 1,707 (86.1%) patients. The readmission rate for SDD vs non-SDD group was similar (0.8% vs 0.9%; P = 0.924). The SDD group had a lower acute complication rate than the non-SDD group (0.8% vs 2.9%; P < 0.001), and there was no difference in the subacute complication rate between groups (P = 0.513). Freedom from all-atrial arrhythmias was comparable between groups (P = 0.212).

CONCLUSIONS

In this large, multicenter prospective registry, the use of a standardized protocol showed the safety of SDD after catheter ablation of paroxysmal and persistent AF. (Real-world Experience of Catheter Ablation for the Treatment of Paroxysmal and Persistent Atrial Fibrillation [REAL-AF]; NCT04088071).

Multicenter experience with andexanet alfa for refractory pericardial bleeding during catheter ablation of atrial fibrillation

INTRODUCTION

Pericardial bleeding is a rare but life-threatening complication of atrial fibrillation (AF) ablation. Patients taking uninterrupted oral anticoagulation (AC) may be at increased risk for refractory bleeding despite pericardiocentesis and administration of protamine. In such cases, andexanet alfa can be given to reverse rivaroxaban or apixaban. In this study, we aim to describe the rate of acute hemostasis and thromboembolic complications with andexanet for refractory pericardial bleeding during AF ablation.

METHODS AND RESULTS

In this multicenter, case series, participating centers identified patients who received a dose of apixaban or rivaroxaban within 24 h of AF ablation, developed refractory pericardial bleeding during the procedure despite pericardiocentesis and administration of protamine and received andexanet. Eleven patients met inclusion criteria, with mean age of 73.5 ± 5.3 years and median CHA₂ DS₂ -VASc score 4 [3-5]. All patients received protamine and pericardiocentesis, and 9 (82%) received blood products. All patients received a bolus of andexanet followed, in all but one, by a 2-h infusion. Acute hemostasis was achieved in eight patients (73%) while three required emergent surgery. One patient (9%) experienced acute ST-elevation myocardial infarction after receiving andexanet. Therapeutic AC was restarted after a mean of 2.2 ± 1.9 days and oral AC was restarted after a mean of 2.9 ± 1.6 days, with no recurrent bleeding.

CONCLUSION

In patients on uninterrupted apixaban or rivaroxaban, who develop refractory pericardial bleeding during AF ablation, andexanet can achieve hemostasis thereby avoiding the need for emergent surgery. However, there is a risk of thromboembolism following administration.

A prospective multi-site registry of real-world experience of catheter ablation for treatment of symptomatic paroxysmal and persistent atrial fibrillation (Real-AF): design and objectives

Purpose

Catheter ablation has become a mainstay therapy for atrial fibrillation (AF) with rapid innovation over the past decade. Variability in ablation techniques may impact efficiency, safety, and efficacy; and the ideal strategy is unknown. Real-world evidence assessing the impact of procedural variations across multiple operators may provide insight into these questions. The Real-world Experience of Catheter Ablation for the Treatment of Symptomatic Paroxysmal (PAF) and Persistent (PsAF) Atrial Fibrillation registry (Real-AF) is a multicenter prospective registry that will enroll patients at high volume centers, including academic institutions and private practices, with operators performing ablations primarily with low fluoroscopy when possible. The study will also evaluate the contribution of advent in technologies and workflows to real-world clinical outcomes.

Methods

Patients presenting at participating centers are screened for enrollment. Data are collected at the time of procedure, 10–12 weeks, and 12 months post procedure and include patient and detailed procedural characteristics, with short and long-term outcomes. Arrhythmia recurrences are monitored through standard of care practice which includes continuous rhythm monitoring at 6 and 12 months, event monitors as needed for routine care or symptoms suggestive of recurrence, EKG performed at every visit, and interrogation of implanted device or ILR when applicable.

Results

Enrollment began in January 2018 with a single site. Additional sites began enrollment in October 2019. Through May 2021, 1,243 patients underwent 1,269 procedures at 13 institutions. Our goal is to enroll 4000 patients.

Discussion

Real-AF’s multiple data sources and detailed procedural information, emphasis on high volume operators, inclusion of low fluoroscopy operators, and use of rigorous standardized follow-up methodology allow systematic documentation of clinical outcomes associated with changes in ablation workflow and technologies over time. Timely data sharing may enable real-time quality improvements in patient care and delivery.

Trial registration

Clinicaltrials.gov: NCT04088071 (registration date: September 12, 2019)

Supplementary Information

The online version contains supplementary material available at 10.1007/s10840-021-01031-w.

Incidence of Cardiac Implantable Electronic Device Complications in Patients With Left Ventricular Assist Devices

OBJECTIVES

The objective of this study was to describe the risk of cardiac implantable electronic devices (CIEDs) complications in patients with left ventricular assist devices (LVADs).

BACKGROUND

Patients with LVADs are predisposed to ventricular arrhythmias and frequently have CIEDs before receiving their LVAD. However, the role of CIED procedures such as generator changes (GC) are unclear in this population, given the potential complications of bleeding and infection.

METHODS

This was a retrospective, multicenter study from January 1, 2012, to September 30, 2018. All patients with LVADs were screened and those who had a CIED GC, implantation, or revision were included in the study and followed until December 31, 2018.

RESULTS

A total of 179 patients across 6 centers had a CIED procedure after LVAD implantation. The mean age was 59.5 ± 13.4, with the cohort comprising mostly men (78%), destination LVAD therapy (53.8%), and GC (66%). The 30-day primary composite endpoint of hematoma or device infection occurred in 34 (19%) patients. The secondary endpoints of rehospitalization within 30 days and appropriate device therapy during follow-up occurred in 40 (22%) and 42 (24%) patients respectively. Of the 126 patients without previous device therapy, 14.3% received appropriate therapy during follow-up.

CONCLUSIONS

In this large, multicenter cohort, we report the incidence of complications for CIED procedures in the LVAD population; specifically, LVAD patients are at increased risk of pocket hematomas, without downstream risk of infection, and do experience a high rate of appropriate device therapies.

A manifesto of collaborative longitudinal cardiovascular care in heart failure

In this document, we outline the challenges faced by patients and clinicians in heart failure, specifically centered around the needed coordination of care among the various subspecialties within cardiovascular medicine. We call for a more organized and collaborative effort among clinicians in primary care, general cardiology, electrophysiology, interventional cardiology, cardiothoracic surgery, cardiac imaging, and heart failure—all caring for mutual patients. Care is contextualized within the framework of two phases: a cardiomyopathy phase and an advanced heart failure phase, each of which lends to different considerations in therapy. Ultimately multidisciplinary coordinated care within cardiovascular medicine may lead to greater patient and clinician satisfaction as well as improved outcomes, but this remains to be investigated.

Physical activity is reduced prior to ventricular arrhythmias in patients with a wearable cardioverter defibrillator

INTRODUCTION

The utility of accelerometer-based activity data to identify patients at risk of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) has not previously been investigated. The aim of the current study was to determine whether physical activity is associated with manifesting spontaneous sustained VT/VF requiring emergent defibrillation in patients with an ejection fraction of ≤35%.

METHODS

Patients consecutively prescribed a wearable cardioverter defibrillator (WCD) from April 2015 to May 2018 were included. Shock data and 4 weeks of physical activity data, beginning with the first week of WCD wear, were analyzed.

RESULTS

Based on the ROC curve outcome generated from 4057 patients, average daily step count during the first week accurately predicted those patients with sustained VT/VF compared to those without (shocked (n = 81) vs nonshocked (n = 3976) area under the curve, c-index = 0.71, 95% CI = 0.65-0.77, P < .001). An average cutoff of 3637 daily steps during week 1 separated the groups. Patients who averaged fewer than 3637 steps per day during the first week of WCD use were 4.3 times more likely to experience a shock than those who walked more than 3637 steps per day (OR = 4.29, 95% CI = 2.58-7.15, P < .001).

DISCUSSION

Average daily step counts are lower in WCD patients who manifest spontaneous VT/VF. Whether these findings represent a causal or correlational relationship, future studies to encourage a minimum daily step count in high-risk patients may impact the incidence of sustained VT/VF.

A Randomised Controlled Trial of Fluid Restriction Compared to Oesophageal Doppler-Guided Goal-Directed Fluid Therapy in Elective Major Colorectal Surgery within an Enhanced Recovery after Surgery Program

There is continued controversy regarding the benefits of goal-directed fluid therapy, with earlier studies showing marked improvement in morbidity and length-of-stay that have not been replicated more recently. The aim of this study was to compare patient outcomes in elective colorectal surgery patients having goal-directed versus restrictive fluid therapy. Inclusion criteria included suitability for an Enhanced Recovery After Surgery care pathway and patients with an American Society of Anesthesiologists Physical Status score of 1 to 3. Patients were intraoperatively randomised to either restrictive or Doppler-guided goal-directed fluid therapy. The primary outcome was length-of-stay; secondary outcomes included complication rate, change in haemodynamic variables and fluid volumes. One hundred patients, 50 in each group, were included in the analysis. Compared to restrictive therapy, goal-directed therapy resulted in a greater volume of intraoperative fluid, 2115 (interquartile range 1350 to 2560) ml versus 1500 (1200 to 2000) ml, P=0.008, and was associated with an increase in Doppler-derived stroke volume index from beginning to end of surgery, 43.7 (16.3) to 54.2 (21.1) ml/m2, P <0.001, in the latter group. Length-of-stay was similar, P=0.421. The number of patients with any complication (minor or major) was similar; 60% (30) versus 52% (26), P=0.42, or major complications, 1 (2%) versus 4 (8%), P=0.36, respectively. The increased perioperative fluid volumes and increased stroke volumes at the end of surgery in patients receiving goal-directed therapy did not translate to a significant difference in length-of-stay and we did not observe a difference in the number of patients experiencing minor or major complications.

Longitudinal strain in Friedreich Ataxia: a potential marker for early left ventricular dysfunction

BACKGROUND

Friedreich's ataxia (FRDA) is a neurodegenerative disorder resulting from deficiency of frataxin, characterized by cardiac hypertrophy associated with heart failure and sudden cardiac death. However, the relationship between remodeling and novel measures of cardiac function such as strain, and the time-dependent changes in these measures are poorly defined.

METHODS AND RESULTS

We compared echocardiographic parameters of cardiac size, hypertrophy, and function in 50 FRDA patients with 50 normal controls and quantified the following measures of cardiac remodeling and function: left ventricular (LV) volumes, mass, relative wall thickness (RWT), ejection fraction (EF), and myocardial strain. Linear regression analysis was used to identify significant differences in echocardiographic parameters in FRDA compared with normal subjects. In analyses adjusted for age, sex, and body surface area, significant differences were observed between parameters of remodeling (LV mass, RWT, and volumes) and function in FRDA patients compared with controls. In particular, longitudinal strain was significantly decreased in FRDA patients compared with controls (-12.4% vs. -16.0%, P < 0.001), despite similar and normal left ventricular ejection fraction (LVEF). Over 3 years of follow-up, there was no change in strain, LV size, LV mass, or LVEF among FRDA patients.

CONCLUSION

Longitudinal strain is reduced in FRDA despite normal LVEF, indicative of subclinical cardiac dysfunction. Given late declines in LVEF in FRDA, longitudinal strain may provide an earlier index of myocardial dysfunction in FRDA.

Clinical characteristics of gout: a hospital case series

INTRODUCTION

Gout is an increasingly common medical problem. The traditional risk factors of male sex and high red meat or alcohol consumption have been joined with newer risks such as increased life expectancy, and the metabolic syndrome (hypertension, diabetes, dyslipidaemia, truncal obesity).

METHODS

This was a retrospective study to determine the epidemiology, clinical features, associated conditions as well as renal related conditions in existing gout patients followed-up in Rheumatology outpatient clinic, Hospital Tuanku Ja'afar, Seremban.

RESULTS

Over a three month period, we identified 54 gouty patients on our follow-up, the majority being male, Malay ethnicity, with the age of onset in the third and fourth decades of life. Commonly associated risk factors were hypertension, hyperlipidaemia and obesity. However, underlying history of diabetes mellitus, alcohol consumption, and family history were not commonly associated with gout in our group of patients. Half of our patients had at least two or more joints involvement. About half of the patients with tophaceous gout had renal impairment.

CONCLUSION

Our series of gout patients highlight the high prevalence of cardiovascular risk factors. The high prevalence of tophi and renal impairment is a cause for concern.

Training in the private sector: what works and how do we increase opportunities?

In Australia 61% of elective surgery takes place in private hospitals where current opportunities for surgical education and training (SET) are limited. The situation will shortly be compounded because of the large increase in local medical graduates, many of whom will aspire to be surgeons. How and where to train these extra surgeons to meet the expanding needs of the community must be addressed. Two models of private sector training are reviewed both of which involved combined training in both private and public sectors. Two second-year (SET 2) positions were created from one public hospital SET position by using the private sector for 3.5 days per week for 3 months of a 6-month rotation. The second model was applicable to post-fellowship training with a fairly even split between public and private sector responsibilities. In the first year, four registrars shared the two 6-month rotations for the SET 2 position. Trainees did the required minimum procedures (range 109-139) with primary operating targets of 20-25% (range 21-32%). The post-fellowship position in colorectal surgery was greatly enhanced by the private sector involvement with regard to operating experience as well as meeting part of the remuneration of the trainee. Successful models for training within the private sector in Australia can be found. To expand training in the private sector there will need to be a cultural shift in the perceptions of surgeons, patients, administrators, and trainees. Funding for posts may be available to those private hospitals that can meet the Royal Australasian College of Surgeons' accreditation standards for posts and hospitals.

The many facets of Notch ligands

The Notch signaling pathway regulates a diverse array of cell types and cellular processes and is tightly regulated by ligand binding. Both canonical and noncanonical Notch ligands have been identified that may account for some of the pleiotropic nature associated with Notch signaling. This review focuses on the molecular mechanisms by which Notch ligands function as signaling agonists and antagonists, and discusses different modes of activating ligands as well as findings that support intrinsic ligand signaling activity independent of Notch. Post-translational modification, proteolytic processing, endocytosis and membrane trafficking, as well as interactions with the actin cytoskeleton may contribute to the recently appreciated multifunctionality of Notch ligands. The regulation of Notch ligand expression by other signaling pathways provides a mechanism to coordinate Notch signaling with multiple cellular and developmental cues. The association of Notch ligands with inherited human disorders and cancer highlights the importance of understanding the molecular nature and activities intrinsic to Notch ligands. Oncogene (2008) 27, 5148-5167; doi:10.1038/onc.2008.229.

The bfl-1 gene is transcriptionally upregulated by the Epstein-Barr virus LMP1, and its expression promotes the survival of a Burkitt's lymphoma cell line

The recently identified bfl-1 gene (also known as A1 or GRS), a homologue of bcl-2, encodes an antiapoptotic protein that suppresses apoptosis induced by the p53 tumor suppressor protein and exhibits proliferative and potent cooperative transforming activities. We show that elevated levels of bfl-1 mRNA are a feature of Epstein-Barr virus (EBV)-immortalized B-cell lines and Burkitt's lymphoma cell lines expressing the full spectrum of EBV latent proteins. Using an EBV-negative Burkitt's lymphoma cell line in which the expression of EBV latent membrane protein 1 (LMP1) is inducibly regulated by tetracycline, we demonstrate that LMP1 expression coincides with a dramatic increase in the level of bfl-1 mRNA. Also in this system, an increase in the level of Bcl-2 protein was seen to occur earlier than that of bcl-2 mRNA, suggesting that both transcriptional and translational mechanisms are involved in the control of Bcl-2 expression by LMP-1. We show that elevated bfl-1 mRNA stability can contribute to this effect of LMP-1, thus providing evidence of a novel mechanism of gene regulation by this EBV protein. Upregulation of bfl-1 by LMP1 was not observed in the T-cell line Jurkat or the epithelial cell line C33A. Ectopic expression of Bfl-1 in an EBV-positive cell line exhibiting a latency type I infection protects against apoptosis induced by growth factor deprivation, thereby providing a functional role for Bfl-1 in this cellular context and adding Bfl-1 to the list of antiapoptotic proteins whose expression is modulated by EBV. This is the first report of the regulation of bfl-1 expression by a viral protein, and this novel finding may thus represent an important link between the EBV oncoprotein LMP1 and its cellular growth-transforming properties.

Population study of common glucose-6-phosphate dehydrogenase mutations in Kuwait

DNA samples from 206 unrelated Kuwaitis of both sexes, i.e. 200 randomly selected individuals and 6 glucose-6-phosphate-dehydrogenase (G6PD)-deficient probands, have been analyzed by the PCR/RFLP technique for mutations underlying the most common G6PD-deficient variants (Mediterranean and A-). At the first step all samples were studied for the 563C-->T and 376A-->G mutations, then the samples positive for 376A-->G were further analyzed for 202G-->A, 680G-->T and 968T-->C mutations. Three mutations (563C-->T, 376A-->G and 202G-->A) were found to be present in the Kuwaiti population at polymorphic frequencies (0.0503, 0.0215 and 0.0111, respectively). Nineteen out of 20 unrelated Kuwaiti chromosomes with 563C-->T had Mediterranean haplotype as judged by 1311C-->T polymorphism. The frequency of G6PD-deficient genotypes was 4.5% (5.73% in males and 2.56% in females).

Extra and central pontine myelinolysis in a child with adrenal insufficiency

We report a 5-year-old patient with adrenal insufficiency (AI) who had a subacute monophasic neurologic illness and brainstem and striatal lesions on brain imaging. The prominent electrolyte abnormalities in AI indicate that extra and central pontine myelinolysis is the likely cause. An association between AI and extra pontine myelinolysis has not previously been reported in children.

TaqI polymorphism in the 3' flanking region of the PI gene among Kuwaiti Arabs and Russians

The Taq1 polymorphism in the 3' flanking region of the PI gene has been reported to be associated with chronic obstructive pulmonary disease (COPD). We have studied the frequency of the Taq1 polymorphism in 117 Kuwaiti Arabs and 110 Russians using PCR/RFLP. The frequency of this polymorphism was found to be 0.235 in the Arabs and 0.027 in the Russians. Such a striking difference in allele frequencies could be due to a 'founder effect' in the Kuwaiti population. However: it may also be that this mutation provides a selective advantage, thus accounting for its fixation at a rather high frequency in some populations. Our results suggest that ethnic composition is a very important factor which should be taken into consideration when studying the association of the Taq1 polymorphism with COPD.

Deletion analysis of the SMN and NAIP genes in Kuwaiti patients with spinal muscular atrophy

Two genes are known to be involved in spinal muscular atrophy (SMA), namely, SMN (survival motor neuron) and NAIP (neuronal apoptosis inhibitory protein). Deletion analysis of these genes has been reported for many ethnic groups. We have extended this analysis to include 15 Arabic patients (11 unrelated cases of type I, which represent practically all of the patients diagnosed within the last 2 years in Kuwait, and 4 type-II cases from a single kinship). Also, 41 healthy relatives (parents and sibs) and 44 control individuals of Arabic origin were analyzed. The homozygous deletions of exons 7 and 8 of the SMN gene were found in all SMA patients studied. Exon 5 of NAIP was homozygously absent in all type-I patients, but was retained in type-II cases. Among members of SMA families, one mother was found to be homozygously deleted for NAIP. All of the control individuals had both normal SMN and NAIP. Our results are in agreement with the general consensus that the incidence of NAIP deletion is higher in the more severe SMA cases. Furthermore, they suggest that SMA type-I chromosomes, with the dual deletion of the SMN and NAIP genes, are more common in Arabs than in patients of other ethnic origin.

The value of critical incident analysis as an educational tool and its relationship to experiential learning

Experiential learning and teaching strategies designed to facilitate this, have become popular in nursing and midwifery education in recent years. It is advocated that such learning enables the development of knowledge, skills and attitudes grounded in practice through the use of reflection on action. One strategy that may be utilised by nursing/midwifery educators to develop reflective ability in both themselves and students is critical incident analysis. It is suggested that critical incident analysis has value and is appropriate for developing interpersonal skills and self-awareness. It is proposed that critical incident analysis is a valuable educational tool which enables nursing/midwifery students to draw on past experiences and make sense of them, not only facilitating learning from clinical practice but also going some way towards bridging the gap between theory and practice.

Branching morphogenesis of human mammary epithelial cells in collagen gels

To study the morphogenesis of human epithelial cells in vitro we have used a three-dimensional collagen matrix and a newly developed mammary epithelial cell line, 1–7 HB2. In standard medium 1–7 HB2 cells formed compact balls/spheres inside collagen type I gels, while cocultivation with various fibroblast cell lines or growth in fibroblast-conditioned media resulted in the appearance of branching structures. At least two different soluble factors secreted by fibroblasts were found to be implicated in the branching morphogenesis. Firstly, hepatocyte growth factor/scatter factor could induce branching in a concentration-dependent manner. Moreover, a polyclonal serum against hepatocyte growth factor/scatter factor completely inhibited the branching morphogenesis induced by medium conditioned by MRC-5 fibroblast cells. In contrast, a morphogenetic activity secreted by human foreskin fibroblasts was identified that appears to be different from hepatocyte growth factor/scatter factor and from a number of other well-characterized growth factors or cytokines. This model system has been used to examine the role of integrins in mammary morphogenesis. The expression of the alpha 2 beta 1, alpha 3 beta 1 and alpha 6 beta 4 integrins was decreased when cells were plated on collagen gels. The addition of specific blocking monoclonal antibodies directed to the alpha 2- and beta 1-integrin subunits to growth media impaired cell-cell interactions and interfered with the formation of compact structures inside collagen gels, suggesting that the alpha 2 beta 1 integrin can control intercellular adhesion in mammary morphogenesis. In contrast one of the blocking monoclonal antibodies against the alpha 3-integrin subunit (P1B5) mimicked the effect of soluble ‘morphogens’. Our results suggest that the modulation of alpha 3 beta 1 activity may represent an important event in the induction of branching morphogenesis of human mammary epithelial cells.

Collagen-induced morphogenesis and expression of the alpha 2-integrin subunit is inhibited in c-erbB2-transfected human mammary epithelial cells

The c-erbB2 (or Her2) oncogene is amplified and/or overexpressed in a significant proportion of breast cancers. To assess the role of the c-erbB2 oncogene in mammary tumorigenesis, we have transfected the corresponding human c-erbB2 cDNA into an immortalized human mammary epithelial cell line, MTSV1-7, that was derived from luminal epithelial cells cultured from milk. Three transfectants expressing different levels of the c-erbB2 gene product have been isolated which form colonies in agar and produce tumours in nude mice with high efficiency. We have observed that MTSV1-7 cells form three-dimensional structures in collagen gels and that alpha 2 beta 1-integrin plays a crucial role in the process of morphogenesis. We now find that the c-erbB2 transfectants exhibit an impaired ability to undergo morphogenesis in collagen gels as compared with the parental cell line or the control neomycin transfectant, and that the degree of impairment is related to the level of c-erbB2 expression. Moreover, overexpression of the c-erbB2 product was found to be correlated with a specific decrease in the expression of alpha 2-integrin subunit and in the alpha 2-mRNA. The breast cancer cell line SKBr3, which carries multiple copies of the c-erbB2 gene and overexpresses the 185-kDa product, was also found to express very low levels of the alpha 2-integrin protein and mRNA. Our results confirm the involvement of the alpha 2 beta 1-integrin in collagen-induced morphogenesis of mammary epithelial cells and suggest that the c-erbB2 gene product may inhibit this morphogenesis by inhibiting the expression of the alpha 2-integrin subunit.

Attenuation of cAMP-mediated responses in MA-10 Leydig tumor cells by genetic manipulation of a cAMP-phosphodiesterase

In order to assess the effect of increased cAMP degradation on the responsiveness on an endocrine cell, we have obtained stable transfectants of MA-10 Leydig tumor cells that overexpress a mammalian cAMP-phosphodiesterase. Two novel cell lines, designated MA-10(P+8) and MA-10(P+29), that express high levels of the transfected enzyme were characterized. Although the basal levels of cAMP in the mutant cell lines are comparable to those of the wild-type cells, the increase in cAMP accumulation elicited by human choriogonadotropin (hCG) is severely blunted. Further studies with MA-10(P+29) show that the ability of hCG to stimulate adenylyl cyclase activity is normal. The failure of MA-10(P+29) cells to accumulate cAMP in response to hCG can be correlated with a similar reduction in hCG-stimulated steroidogenesis. On the other hand, the maximal steroidogenic response of MA-10(P+29) cells to dibutyryl cAMP, a cAMP analogue that is fairly resistant to phosphodiesterase degradation, is normal. We also show that the ability of these cells to respond to hCG with increased cAMP accumulation and steroid synthesis can be restored with a specific phosphodiesterase inhibitor. These results demonstrate that overexpression of a cAMP-phosphodiesterase in MA-10 cells limits the levels of cAMP attained under hCG stimulation and supresses the steroidogenic response of these cells to hCG. Since gonadotropins increase the cAMP-phosphodiesterase activity in their target cells, these findings also provide evidence that this regulation plays a major role in the modulation of cell responsiveness. Last, these new cell lines should be valuable in the study of the actions of cAMP because they express a conditional and reversible cAMP-resistant phenotype.

Acute steroid-induced tetraplegia following status asthmaticus

A 10-year-old girl was treated for an acute asthmatic attack with ventilation and a high-dose steroids regimen. An areflexic paralysis of the four limbs was noted when artificial ventilatory support was withdrawn. Electromyography and a muscle biopsy revealed marked myopathic features. We discuss the unusual presentation of an acute steroid-induced myopathy in an asthmatic patient.

The value of surveillance testing in childhood brain tumors

Follow-up procedures in children with brain tumors are designed to confirm tumor response to initial therapy, identify recurrence or progression at the time of potential secondary treatment, and establish the patterns of failure. Serial use of neurologic examinations and computerized tomography scans are outlined for all tumor types. Tumors capable of subarachnoid metastasis (medulloblastoma, ependymomas, pineal/suprasellar germ cell tumors, and pineoblastoma) require periodic assessment of the neuraxis by cerebrospinal fluid (CSF) cytology and myelography to establish the frequency of subclinical meningeal seeding in study settings. Serial analysis of specific biochemical markers for medulloblastoma (CSF polyamines) and germ cell tumors (serum and CSF alpha-fetoprotein and beta-human chorionic gonadotropin) are suggested. Serial evoked potentials in brain stem gliomas are recommended.

The argument for a combined cancer consortium research data base

Epidemiologic data that were obtained through the SEER registry (Surveillance Epidemiology End Results Program) are presented. Survival statistics for five major brain tumor types in childhood are presented for the years 1968 through 1979. Further survival statistics are compared in patients treated in community hospitals versus university hospitals. The lack of uniform reporting, absence of pathologic conformation, and limited number of patients seen throughout the country are emphasized. There is a need for the establishment of a data base composed of the member institutions of the childhood cancer consortiums. This data base would address questions of patterns of failure, benefits of surgical and clinical staging, and the value of a new putative pathologic grading system. Additionally, the opportunity to collect these patients should permit identification of long-term treatment effects. Identification of early morbidity may lead to modification of treatment programs. A data base containing treatment and diagnostic parameters would allow significant cross-correlations and would lead to the design of future studies that are based upon accurate data.

Pediatric radionuclide ventriculography

Computed tomography is the standard diagnostic examination employed to identify the morbid anatomy of cerebrospinal fluid spaces in children. This noninvasive technique provides excellent anatomic information. However, CT only indirectly characterizes the cerebral spinal fluid pathways. When it is necessary to determine precise bulk cerebrospinal fluid flow for surgical correction, then radionuclide ventriculography (RNV) is a useful adjunctive procedure.