Corrosion of Pacemaker Electrodes

As improvements in pacemaker components and design increase pacemaker life, problems with other components may emerge such as corrosion of the electrodes. Explanted electrodes were examined under a scanning electron microscope and the degree of corrosion was graded and correlated with the reasons for expiantation, the status of the explanted pacemaker, and the duration of the implant. Fifty-six explanted electrodes were removed for loss of capture or sensing, pacemaker extrusion, broken wires, or after death. A numerical grading system was used to qualitate the degree of corrosion. The pacemaker itself was retrieved in 50 cases, permitting evaluation of the entire pacing system. The dc component of the pacemaker output was measured. Without She aid of magnification most electrodes appeared shiny and smooth. With one exception all corrosion was microscopic. Significant corrosion was seen on all pacemaker electrodes that had been connected to pacemakers with dc offset currents greater than 5 microamperes. All except the "youngest" explanted electrode showed some degree of corrosion. The data suggest that corrosion was directly related to the duration of implantation. With the possible exception of one case, no consistent adverse clinical effects were observed, even when electrodes were heavily corroded. Whether or not corrosion eventually will progress to the point that clinical problems become manifest cannot be predicted at this time.     

Studies on Reproduction in Rats with Meclofenamate Sodium, a Nonsteroidal Anti-inflammatory Agent

Studies on Reproduction in Rats with Meclofenamate Sodium, aNonsteroidal Anti-inflammatory Agent. PETRERE, J. A., HUMPHREY,R. R., ANDERSON, J. A., FITZGERALD, J. E., AND DE LA IGLESIA,F. A. (1985). Fundam. Appl. Toxicol. 5, 665–671. Reproductionand teratology studies were performed in rats given meclofenamatesodium, a nonsteroidal anti-inflammatory agent. Dosages of 0,3, 6, and 9 mg/kg were administered orally as dietary admixturesin the Fertility and Perinatal-Postnatal studies. In the Teratologystudy, dosages of 10, 12, 15, and 20 mg/kg were administeredby intragastric intubation. In the Male-Fertility study no adverseeffects on fertility or litter and offspring parameters wereobserved in two generations. In the Female-Fertility and Perinatal-Postnatalstudies, maternal toxicity (death associated with intestinalulceration and adhesions) was particularly evident during lactation.Prolonged gestation periods, decreased weanling weights, andincreased weanling mortality were evident at dosages of 6 and9 mg/kg. Increased postimplantation loss occurred at 6 and 9mg/kg in the Term Sacrifice subgroup of the Female-Fertilitystudy. Fertility rates were unaffected and all other litterand offspring parameters of the F₁ and F₂ generations appearednormal. In the Teratology study no adverse effects on embryonicor fetal development were evident at maternally toxic dosagesup to 20 mg/kg. © 1985 Society of Texicology.     

BLOOD TRANSFUSION: A POSSIBLE RISK FACTOR IN RETROLENTAL FIBROPLASIA

ABSTRACT. Clark, C, Gibbs, J. A. H., Maniello, R., Outerbridge, E. W., and Aranda, J. V. (Department of Newborn Medicine, McGill University, Montreal Children's Hospital Research Institute, Montreal, Quebec, Canada). Blood transfusion: A possible risk factor in retrolental Fibroplasia. Acta Paediatr Scand, 70:535,.–The effect of blood transfusion on the occurrence of RLF was evaluated in 58 infants who weighed less than 1 001 g at birth (Group I) and 70 oxygen treated infants of various birth weights (Group 11). Although there was no significant difference between Group 1 infants with or without exchange transfusion as to birth weight, gestational age, duration of oxygen therapy, peak Po₂'s, or multiple births, there was a significantly increased incidence of pre-retrolental fibroplasia in transfused over non-transfused Group II infants. When Group II infants were stratified for prematurity and oxygen duration, this difference persisted in those not already at risk for RLF. This increased incidence of retinopathy in transfused infants suggests that blood transfusion may be a risk factor in the pathogenesis of RLF.     

Immunomodulation by Metals

A symposium entitled Immunomodulation by Metals was held atthe 32nd Annual Meeting of the Society of Toxicology (SOT) inNew Orleans, Louisiana. The symposium was cosponsored by theImmunotoxicology and Metals Specialty Sections of SOT and wasdesigned to describe the types of adverse immunological reactionswhich occur in response to environmental and/or occupationalexposure to metals. Epidemiological evidence and underlyingmechanisms responsible for the observed alterations were alsodiscussed. The following is a summary of each of the individualpresentations.     

Nutrition and Health Status Assessment of Community-residing Elderly in New York City: A Pilot Study

Ninety-five percent of persons over the age of 65 years live in the community and benefit from community-based health and nutrition services. The purpose of this project was to evaluate diet, function, and mental health in 40 men and women aged 65 years and older who were residing in a large metropolitan community. Nutritional status was assessed using two 24-hour recalls, 5 days of food records, a food frequency, and anthropometric measurements. Participants responded to standardized activities of daily living and instrumental activities of daily living instruments and an investigator-developed, performance-based appraisal of food preparation and management. Cognition and mood were assessed using the Folstein Mini-Mental Examination and the Yesavage Depression Scale. The nutrient intakes for individuals were compared with the Recommended Dietary Allowances (RDAs) and the Food Guide Pyramid. Mean energy intake was 1,625 kcal (range=787 to 2,910 kcal); 7 persons consumed more than 2,000 kcal. The mean vitamin and mineral intake for participants met the RDAs except for calcium, vitamin D, zinc, and magnesium intakes. The average percentages of carbohydrate, protein, and fat were 53%, 16%, and 30%, respectively. Nutritional assessments of subjects with and without congregate meals were contrasted. Six of the 13 congregate-meal participants were at nutritional risk, compared with 6 of 27 not receiving congregate meals. The interrelationships of diet, functional status, and mental health factors were examined along with recommendations for future data collection in similar studies. J Am Diet Assoc. 1998;98:554-558.     

NURSING BEHAVIOUR, PROLACTIN AND POSTPARTUM AMENORRHOEA DURING PROLONGED LACTATION IN AMERICAN AND KUNG MOTHERS

In order to determine the effects of protracted nursing in American women, blood was collected hourly for 24 h and nursing periods recorded in 20 mothers, 10 amenorrhoeic, 3 3/4 to 17 1/4 months postpartum (PP), and 10 menstruating, 5 1/4 to 46 months PP. These data were compared to the daytime nursing behaviour and 1000-1100 h PRL of women among !Kung hunter-gatherers of Botswana, a non-contraceptive using population with a birth space interval of greater than 3 years. Intense nursing behaviour maintained amenorrhoea and hyperprolactinaemia for 1 to nearly 2 years PP in both American and !Kung mothers. Among Americans, 80 min of nursing per day, in conjunction with a minimum of six nursing episodes, was highly predictive of remaining amenorrhoeic up to 18 months PP. Amenorrhoea was always accompanied by hyperprolactinaemia, but delay in the onset of menses was related more to nursing behaviour than to a particular 24 h PRL level. The 1000-1100 h sample is equivalent to and about half of the 24 h mean in high and low intensity nursers, respectively. The !Kung women were similar to the high intensity nursing American women in 1000-1100 h PRL, percent amenorrhoeic, and the number of minutes of daytime nursing.