Criteria for identifying allergenic foods of public health importance.

The World Health Organisation and other food safety authorities recognise food allergy as a significant public health concern due to the high prevalence and potential severity of the condition and the impact it has on the quality of life and economy. A public health perspective focuses on risk management at the societal level rather than precautions taken by individuals. Allergen lists were originally drawn up on the basis of a combination of prevalence and severity information, but data to document inclusion were limited. Since then the number of allergenic foods for which reactions have been well documented has grown considerably. Yet, most of them are of limited significance to public health. To address food allergy issues from the point of view of risk management, an expert group appointed by the Food Allergy Task Force of the International Life Sciences Institute ILSI Europe reviewed the criteria. We propose a revised set of criteria together with a framework which can be used to help decide which allergenic foods are of sufficient public health importance to be included in allergen lists. Criteria include clinical issues (diagnosis, potency of allergen, severity of reactions), population elements (prevalence, exposure) and modulating factors (food processing). In the framework, data providing evidence for these criteria are weighted according to quality, using a ranking derived from evidence-based medicine. The advantage of this approach is that it makes explicit each of the considerations, thereby rendering the whole process more transparent for all stakeholders.

The application of post-market monitoring to novel foods.

The role of post-market monitoring (PMM) in the safety assessment of novel foods is critically discussed in order to derive guidelines as to in which situations the application of PMM might be warranted. Available data sources on food consumption and health status, and the methodologies for generating such data are reviewed. The paper suggests improvements to make them more applicable for PMM purposes. It is concluded that any PMM programme must be a hypothesis-driven scientific exercise. PMM can have a role as a complement to, but not as a replacement for, a comprehensive pre-market safety assessment. Its use may be appropriate to confirm that product use is as predicted in the pre-market assessment; to provide reassurance that effects observed in the pre-market assessment occur with no greater frequency or intensity in the post-market phase than anticipated; and to investigate the significance of any adverse effects reported by consumers after market-launch. However PMM is insufficiently powerful to test the hypothesis that any effects seen in the pre-market assessment are absent in the post-market phase. Current methodologies place limitations on what PMM can achieve. PMM should only be used when triggered by or when the focus is on specific evidence-based questions.

History of safe use as applied to the safety assessment of novel foods and foods derived from genetically modified organisms.

Very few traditional foods that are consumed have been subjected to systematic toxicological and nutritional assessment, yet because of their long history and customary preparation and use and absence of evidence of harm, they are generally regarded as safe to eat. This 'history of safe use' of traditional foods forms the benchmark for the comparative safety assessment of novel foods, and of foods derived from genetically modified organisms. However, the concept is hard to define, since it relates to an existing body of information which describes the safety profile of a food, rather than a precise checklist of criteria. The term should be regarded as a working concept used to assist the safety assessment of a food product. Important factors in establishing a history of safe use include: the period over which the traditional food has been consumed; the way in which it has been prepared and used and at what intake levels; its composition and the results of animal studies and observations from human exposure. This paper is aimed to assist food safety professionals in the safety evaluation and regulation of novel foods and foods derived from genetically modified organisms, by describing the practical application and use of the concept of 'history of safe use'.

Effect of different location of atrial lead position on nearfield and farfield electrograms in dual chamber pacemaker-defibrillators.

The normal functioning of dual chamber pacemaker-cardioverter defibrillator (AV pacer/ICD) may be affected by oversensing of the farfield R wave (FFRW) by the atrial channel. This study aimed to investigate whether placement of the AV pacer/ICD's atrial lead at a lateral (LAT) wall location compared to a medial (MED) location i.e. the appendage of the right atrium, would reduce the amplitude of FFRWs but not the nearfield atrial electrograms (AEGMs) during sinus rhythm (SR) and ventricular fibrillation (VF). In 17 patients, real time electrograms were recorded during SR and induced VF through the atrial lead initially at the MED and subsequently at the LAT location. In 10 patients the electrograms in SR were also recorded on a computerized data acquisition and recording system at different band-pass filter settings. Although FFRWs were recorded both at MED and LAT locations, they were much smaller, 3.5+/-4.1mm during SR and 1.7+/-2.2mm during VF at the LAT location. At 30-500Hz band-pass filter, lower amplitudes of FFRWs 0.14+/-0.09 mV were recorded at the LAT location. The V/A ratios of the amplitudes of FFRWs and AEGMs were smaller at the LAT location during SR and VF. The nearfield AEGMs were of similar amplitudes at the MED and LAT locations. These data indicate that lower amplitudes of FFRWs are recorded by placement of the atrial lead at the lateral wall of the right atrium. Oversensing of FFRWs may be prevented to improve functioning of the AV pacer-ICD.

Feasibility, safety, and determinants of extraction time of percutaneous extraction of endocardial implantable cardioverter defibrillator leads by intravascular countertraction method.

Previous studies of the removal of implantable cardioverter defibrillator (ICD) leads have been restricted to case reports or small series. In this report, we describe our experience in ICD lead extraction by intravascular countertraction method using Cook's extraction kit. A total of 47 high-voltage (HV) leads, 3 rate sensing (S) leads, and 2 subcutaneous arrays were removed from 42 patients (33 men, 9 women; mean age 59 years [range 14 to 81]). One HV superior vena cava (SVC) lead and 11 HV right ventricular (RV) leads were explanted by manual traction only and defined in the "lead removal" category. One S lead was removed using a femoral venous approach. The remaining 37 leads were explanted by SVC approach using extraction sheaths and defined in the "lead extraction" category. Twenty leads were extracted for "infectious" (group A) and 17 leads for "noninfectious" (group B) etiologies for which extraction times of 27.0+/-18.0 and 27.0+/-15.0 minutes (mean+/-SD), respectively, were not different. Although extraction time, 34.0+/-11.0 minutes, for leads implanted for >48 months was longer than 23.0+/-16.0, 28.0+/-18.0, and 24.0+/-14.0 minutes, for leads with implant durations of 12, 24, and 48 months, respectively, such differences were not statistically significant. The extraction time, however, was directly related to the degree of fibrosis around the lead, 39.0+/-15.0 minutes for leads with severe fibrosis compared with 13.0+/-6.0 minutes for the leads with mild fibrosis (p<0.001). Patient's age, sex, or history of coronary artery bypass graft surgery did not significantly affect extraction time. All except the initial 2 lead extractions were performed in the electrophysiology laboratory. No mortality or serious complications associated with the procedure using these methods were observed.

Efficacy and safety of catheter ablation in octogenarians.

OBJECTIVES: To determine whether catheter ablation is safe and effective in patients over the age of 80. BACKGROUND: There is a tendency to withhold invasive therapy in the elderly until it has been proven safe and effective. METHODS: Over a two-year period from February 1, 1996 to February 1, 1998, 695 consecutive patients underwent 744 catheter ablation procedures of supraventricular and ventricular arrhythmias. These patients were divided into three groups based on age: > or =80 years, 60 to 79 years and <60 years. Acute ablation success, using standard criteria and complication rates for these three groups were determined. RESULTS: There were 37 patients > or =80 years, 275 patients 60 to 79 years and 383 patients <60 years old. The overall acute ablation success rate for the entire group was 95% with no difference in rates among the three groups (97%, > or =80 years; 94%, 60-79 years; 95%, <60 years). The percentage of patients undergoing His bundle ablation was greatest in the > or =80-year-old group (43% vs. 19% vs. 2%, p < 0.01), and the percentage of patients undergoing accessory pathway ablation was greatest in the <60-year-old patients (0% vs. 4% vs. 25%, p < 0.01). The overall complication rate for the entire group was 2.6%, and there was only one major/life-threatening complication. There was no difference in complication rates among the groups (0%, > or =80 years; 2.2%, 60 to 79 years; 3.1%, <60 years). Based on the sample size, the 95% confidence interval is 0% to 7.8% for an adverse event in the octogenarian. CONCLUSIONS: Catheter ablative therapy for the arrhythmias attempted in the very elderly appears to be effective with low risk. Ablation results appear to be comparable with those noted in younger patients.

Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia after orthotopic heart transplantation.

Patients with orthotopic heart transplantation may develop a variety of arrhythmias. Successful radiofrequency catheter ablation for tachyarrhythmias from manifest and concealed accessory bypass tracts in transplant patients has been previously reported. We present a patient with orthotopic heart transplantation who developed typical atrioventricular nodal tachycardia, which was successfully treated by radiofrequency catheter ablation.

Coronary artery disease in identical twins.

The incidence of coronary artery disease in identical twins is unknown. The knowledge of ischemic heart disease in this patient population is represented by case reports. There is considerable controversy regarding the environmental and genetic factors that play a role in the pathogenesis of this disorder. The natural history of coronary artery disease in an asymptomatic twin with a symptomatic counterpart is unclear. We present a case report and literature review of coronary artery disease in identical twins. On the basis of our patient and the information of other patients, asymptomatic twins of symptomatic counterparts require aggressive assessment and management for occult coronary artery disease.

Amiodarone-associated hemoptysis.

Amiodarone is a benzofuran derivative with a chemical structure similar to thyroxine. Originally introduced to treat angina pectoris, amiodarone was found to have antiarrhythmic properties, and in 1985, was approved in the United States for treatment of life-threatening ventricular arrhythmias. It is now used for various ventricular and supraventricular arrhythmias refractory to conventional first-line medications, and as a result, side effects have been observed with increased frequency. The most severe and potentially life-threatening of these side effects is the development of pulmonary toxicity. Typically, amiodarone pulmonary toxicity (APT) is manifested by acute pneumonitis and chronic fibrosis. Amiodarone-associated hemoptysis (AAH) is a rare occurrence. The authors describe a case of AAH successfully treated with cessation of drug and steroid therapy.

Temporary epicardial atrial pacing electrodes: duration of effectiveness based on position.

BACKGROUND: To investigate the duration of effectiveness in the postoperative period of temporary epicardial atrial pacing electrodes on the right atrium, based on position. METHODS: The function of temporary epicardial atrial pacing electrodes were examined in 55 patients undergoing coronary artery bypass grafting from March 20, 1996, to July 31, 1996, at Allegheny University Hospitals, Hahnemann Division, Philadelphia, PA. There were 41 male and 14 female patients. The mean age was 71 years (range 35 to 86 years). Two atrial and two ventricular temporary epicardial pacing electrodes were placed at the termination of cardiopulmonary bypass. One atrial electrode was placed on the body of the right atrium at the junction of the superior vena cava (body electrode); the other was passed through the pursestring of the atrial cannulation site (appendage electrode). RESULTS: The mean thresholds for the atrial body electrodes on the operative day and postoperative days 1 and 2 were 4.96, 6.67, and 6.80 mA, respectively. The mean thresholds for the atrial appendage electrodes were 5.98, 7.50, and 8.59 mA, respectively. CONCLUSIONS: Temporary epicardial atrial pacing electrodes are more effective when the wires are placed in the atrial body of the right atrium than if they are wrapped within the pursestring of the right atrial appendage. As a result of these findings, the common practice of placing the pacing wire through pursestring tissue should be abandoned.

Management of infected implantable cardiac defibrillators.

BACKGROUND: The implantable cardiac defibrillator (ICD) was introduced clinically in 1980 for the management of ventricular arrhythmias. METHODS: From January 31, 1989, through May 29, 1996, 329 ICD devices were implanted at Allegheny University Hospital, Hahnemann Division, Philadelphia, Pennsylvania. All device-related infections were examined. RESULTS: Fifteen patients (5%) experienced infection of the generator component of the ICD. There were 14 male and 1 female patients with a mean age of 62 years (range, 38 to 79 years). All infections involved the generator with or without other component involvement. Complete removal of the system was performed in 7 patients, partial removal in 5, and the entire system was left intact in 3. In 4 patients (27%), further procedures were performed to remove additional infection. Three patients (20%) died during the hospital stay. CONCLUSIONS: Infection of ICD devices is a devastating event. We favor complete removal of the ICD generator and all the components when possible. Partial removal of the ICD unit (ie, generator only) is reserved for patients in whom the risk of complete removal is too high and infection is confined to the generator only.

Study of myelin purity in relation to axonal contaminants.

Axonal remnants are considered a probable source of contamination of isolated myelin in view of the relatively tight axon-glial intercellular junction. Using the rabbit optic system to label specifically axonal components, we have found the levels of such contaminants to depend on the myelin isolation procedure, the tissue source, and the nature of the contaminant. A procedure employing repetitive treatments with EGTA was found to be highly effective in removing proline-labeled axonal proteins, the estimated upper limit of such contamination being approximately 0.6-1.2% of the myelin protein. The standard isolation procedure of Norton and Poduslo, supplemented with an additional discontinuous gradient step, proved equally effective in removing rapidly transported proteins from myelin isolated from the superior colliculus or lateral geniculate body. When the optic tract was the source, however, the EGTA procedure proved more effective in removing both rapidly and slowly transported proteins. Axonal gangliosides labeled with N-[3H] acetylmannosamine were efficiently removed by both procedures, adding support to the proposition that gangliosides detected in isolated myelin are intrinsic to that membrane.