The Usefulness of a Stretch-Polyester Pouch to Encase Implanted Pacemakers and Defibrillators

This study was undertaken to assess the effects of enclosing permanent pacemaker and ICD pulse generators in a stretch-polyester pouch prior to implantation. Follow-up of 223 patients with oversized pacemakers and with ICDs and 344 witb standard-sized pacemaker pulse generators showed that the pouch was effective in decreasing the frequency of pulse generator migration and extrusion.     

Chronic Toxicity/Oncogenicity of Dimethylformamide in Rats and Mice Following Inhalation Exposure

The potential chronic toxicity and oncogenicity of dimethylformamide(DMF) was evaluated by exposing male and female rats and miceto 0, 25, 100, or 400 ppm DMF for 6 hr/day, 5 days/week for18 months (mice) or 2 years (rats). Clinical pathology was evaluatedat 3, 6, 12, 18, and 24 (rats only) months. An interim euthanasiafor rats occurred at 12 months and hepatic cell proliferationin rats and mice was examined at 2 weeks, 3 months, and 12 months.No compound-related effects on clinical observations or survivalwere observed. Body weights of rats exposed to 100 (males only)and 400 ppm were reduced. Conversely, body weights were increasedin 400 ppm mice. No hematologic changes were observed in eitherspecies. Serum sorbitol dehydrogenase activity was increasedin rats exposed to 100 or 400 ppm. There were no compound-relatedeffects on the estrous cycle of rats or mice at any concentration.Compound-related morphological changes were observed only inthe liver. In rats, exposure to 100 and 400 ppm produced increasedrelative liver weights, centrilobular hepatocellular hypertrophy,lipofuscin/hemosiderin accumulation in Kupifer cells, and centrilobularsingle cell necrosis (400 ppm only). In mice, increased liverweights (100 ppm males, 400 ppm both sexes), centrilobular hepatocellularhypertrophy, accumulation of lipofuscin/hemosiderin in Kupffercells, and centrilobular single cell necrosis were observedin all exposure groups. These observations occurred in a dose-responsefashion and were minimal at 25 ppm. No increase in hepatic cellproliferation was seen in mice or female rats. Slightly higherproliferation was seen in male rats exposed to 400 ppm at 2weeks and 3 months but not at 12 months. Dimethylformamide wasnot oncogenic under these experimental conditions in eitherthe rat or mouse.     

Notation System and Overlay Diagrams for the Analysis of Paced Electrocardiograms

With the advent of adaptive dual-chamber pacing, the interaction between the pacemaker and the heart is becoming increasingly complex and the interpretation of paced electrocardiograms more difficult. We have developed a set of notation conventions for use in teaching and rhythm-atrip analysis. Easily-drawn symbols delineate successful, unsuccessful, and inhibited pacing and sensing events as well as refractory and blanking periods. Another application is to generate movable transparent overlays after programming a pacemaker, to be used in interpreting subsequent rhythm strips.     

Pseudomalfunctions of Dual-Chamber Pacemakers

La prolifération de la stimulation auriculoventriculaire a crée de nombreux cas de "pseudo-dysfonctionnemenl" du stimulateur. En ce qui concerne ľinterpretation electrocardiographique, il est devenu parfois impossible de faire la distinction entre normal et anormal. La classification et les critères de ces phénomenes sont décrits. Il semble que seule la connaissance parfaite du fonctionnement de cheque stimulateur préviendra la fausse interprétation des tracés éléctrocardiographiques.
The proliferation of dual-chamber pacemakers has created a host of electrocardiography problems relating to interpretation. The term "pseudomalfunction" identifies an electrocardiographic finding that looks like pacemaker malfunction but is not. Several different models of dual-chamber pacemakers, which are either presently available or in clinical evaluation, produce different types of pseudomalfunc-tions. These are classified and described. Intimate knowledge of individual pacemaker characteristics is required for proper evaluation of these units.     

Gastrointestinal motor function in diabetes mellitus: Relationship to blood glucose concentrations

Abstract The application of novel investigative techniques has established that there is a high prevalence of disordered gastrointestinal motor function in patients with diabetes mellitus and has provided insights into its pathogenesis and clinical significance. Acute changes in the blood glucose concentration, even within the normal postprandial range, affect both gastrointestinal motor function and the perception of sensations arising from the gastrointestinal tract. Gastric emptying is slower during hyperglycaemia and accelerated during hypoglycaemia; the perception of gastric distension is greater during hyperglycaemia than euglycaemia. The pathways mediating the effects of the blood glucose concentration on gut motility and sensation are poorly defined. The rate of gastric emptying is an important determinant of postprandial blood glucose concentrations and there is increasing evidence that gastric emptying can be modulated therapeutically in order to optimize glycaemic control in patients with diabetes.     

Profound suppression of cellular proliferation mediated by the secretions of nematodes

Loss of T lymphocyte proliferation and the emergence of a host response that is dominated by a Th2-type profile are well-established features of human filarial infection. Downregulation and modulation of host T cell responses during lymphatic filariasis has been investigated by implantation of parasite stages into inbred mice. Adherent peritoneal exudate cells (PEC) from mice transplanted with adult or larval Brugia malayi parasites are profoundly anti-proliferative but do not prevent antigen-specific cytokine production by T cells. We demonstrate here that the excretory/secretory (E/S) products of the adult parasite are sufficient to induce PEC that block proliferation if injected daily into mice. We have previously shown that in vivo production of host IL-4 is required for the generation of suppressive cells. Because the induction of host IL-4 is characteristic of infection with nematodes, we asked whether E/S from two other nematode parasites, Nippostrongylus braziliensis and Toxocara canis were also capable of generating a suppressor cell population. Injection of E/S from these two parasites also led to a reduction in T cell proliferation suggesting that this mechanism of down-regulating host responses is a feature common to nematode parasites .