Failure of Rate Responsive Ventricular Pacing to Improve Physiological Performance in the Univentricular Heart

The physiological efficacy of single chamber, rate responsive ventricular pacing (VVIR) is unknown for symptomatic patients following the Fontan procedure for univentricular hearts. A total of six postoperative children, ages 6–21 years (mean 13), with symptomatic bradycardia requiring pacing therapy, underwent comparative treadmill exercise testing in randomized fixed rate (VVI) and VVIR pacing modes. In all instances, implanted activity pulse generators (Medtronic Model 8403) were programmed to identical age-appropriate low paced rates during WI and VVIR modes with the upper rate response at 150 ppm. All studies were performed at least 2 weeks apart. Physiological values of heart rate, blood pressure, work rate (watts), oxygen comsumption (VO₂), carbon dioxide production (VCO₂), and respiratory exchange ratio (RER) were monitored continuously during each test using a 1 minute incremental treadmill protocol. Ventilatory anaerobic threshold (VAT) was calculated from VO₂, VCO₂, and minute ventilation. The results demonstrated that although there was a significant increase in paced heart rate per minute throughout exercise (P < 0.01) with VVIR pacing, maximum watts, VO₂, and VAT remained unchanged. These findings indicate that in spite of an improved chronotropic response to exercise, children with Univentricular hearts following the Fontan procedure continue to demonstrate altered hemodynamics which negate potential benefits of VVIR pacing.     

Assignment of the human gene for β-glycerol phosphatase to chromosome 8

The segregation of the human gene for β-glycerol phosphatase (GPB) was examined in human-Syrian hamster and human-Chinese hamster somatic cell hybrids. Electrophoretic analysis of the GPB in hybrids suggested that the enzyme is a dimer. Human GPB cosegregated with chromosome 8 in the twenty-five hybrids examined.     

A pharmacotherapy review of the novel,oral antithrombotics

Coagulation disorders account for a high incidence of death in the U.S. due to stroke, myocardial infarction, and venous thromboembolism. In the past few years, numerous agents have been brought to market for the treatment of thromboembolism or prevention of thromboembolism. Similar to warfarin, these agents can cause bleeding disorders, which may exacerbate dental care treatment plans. This literature review examines the newer agents for the treatment of thromboembolism disorders, common side effects and drug interactions, the specific medical conditions each agent treats, and the dental perspective on how to medically management patients prescribed these medications.     

Modified Split‐Cast Technique: A New,Timesaving Clinical Remount Technique

Interocclusal discrepancies can be eliminated by a clinical remount procedure, but most practitioners avoid it because of the time involved. This article introduces a new timesaving method, the modified split‐cast technique. It uses a semi‐adjustable articulator, tin foil as plaster separator, and an addition‐type, silicone bite‐registration material. The technician does most of the remounting procedures before the denture delivery appointment, so the dentist spends very little time chairside to complete the clinical remount procedure. Compared with the conventional and two other remounting techniques, the new technique is faster and easier to manipulate.     

Murine Intestinal Humoral Responses in Chronic Schistosoma mansoni Infections

Specific and non-specific production of immunoglobulins (Ig) by the intestinal mucosa was examined in mice infected with the human blood fluke Schistosoma mansoni. Ileal and colonic mucosal tissue samples were cultured for 2 days, the medium replaced and the culture continued for a further 2 days. Ig concentrations and specific antibodies to soluble schistosome egg antigens in culture supernatants were estimated by isotype-specific ELISA. Cultured mucosae from control mice produced little IgG, but significant amounts of IgA and IgM on prolonged culture. IgG concentrations were increased in infected animals, mainly in the initial culture period, indicative of systemic, rather than local origins. By contrast, significantly increased local production of IgA and IgM occurred after the start of egg deposition in the intestinal mucosae. Although specific anti-egg antibodies of the IgG and IgM class were detected, none of the local IgA response was specific for schistosome eggs. We conclude that specific intestinal immune responses to schistosome eggs reflect systemic responses, whereas locally increased IgA production is largely non-specific. This pattern of response is likely to be related to the prior systemic exposure to schistosome eggs, which results in polyclonal local B-cell activation, but fails to trigger an antigen-specific IgA mucosal response.