The Influence of Advertising on Tobacco Consumption: a reply to Jackson & Ekelund

This paper re-examines the model for quarterly cigarette consumption presented earlier (Chetwynd et al., 1988) in the light of criticisms by Jackson & Ekelund of a number of possible deficiencies in the econometric procedures employed. A thorough interrogation of the model has been pursued using a comprehensive battery of econometric testing procedures which go beyond those suggested by Jackson & Ekelund. The model is found to perform well against all of these tests and the original conclusions drawn from the model are sustained, including the significant impact of advertising on aggregate cigarette consumption.     

The Involvement of Dipeptidyl Peptidase IV in Brush-border Degradation of GRF(1–29)NH2 by Intestinal Mucosal Cells

GRF(1–29)NH₂ is degraded mainly by dipeptidyl peptidase IV (DPP IV) in plasma, resulting in inactivated GRF(3–29)NH₂. To understand whether improving stability of GRF(1–29)NH₂ in the plasma will result in enhanced stability in intestinal mucosal cells, stability of GRF(1–29)NH₂ and [desNH₂Tyr¹,d -Ala²,Ala¹⁵]-GRF(1–29)NH₂ in rat intestine brush-border membrane and homogenate was examined. [desNH₂Tyr¹,d -Ala²,Ala¹⁵]-GRF(1–29)NH₂, resistant to plasma DPP IV, was much more stable than GRF(1–29)NH₂ in enterocytes. Gradient HPLC analysis, mass balance analysis and studies of inhibitor effects revealed that GRF(3–29)NH₂ was the major metabolite of GRF(1–29)NH₂ due to the action of DPP IV during incubation with brush-border membranes. It is concluded that the design of peptide analogues to resist plasma enzymes dramatically increases stability in intestinal epithelium.     

β-Endorphin: peripheral opioid activity of homologues from six species

The peripheral opioid activity of six homologous β-endorphins (β-EPs) were assayed on the guinea pig ileum and the vas deferens of the mouse, the rat and the rabbit. In the guinea pig ileum assay, human β-EP (βh-EP) was less potent than camel, turkey, and ostrich β-EPs, of the same potency as equine β-EP and more active than des-acetyl salmon β-EP. In the rat vas deferens, mammalian β-EPs showed higher activity than those from the bird and the fish, whereas in the mouse vas deferens assay, βh-EP is more active than those from other species. In the rabbit vas deferens, however, all homologous β-EPs show very weak activity. The relative potency of β-EP homologues obtained from rat vas deferens assay is in good correlation with the analgesic potency, while the receptor binding activity does not correlate with any of the four bioassays, but appears to be related to the charge properties of the peptides.     

Effect of Antiarrhythmic Drugs on Defibrillation Threshold: Case Report of an Adverse Effect of Mexiletine and Review of the Literature

Antiarrhythmic agents can influence defibrillation threshold (DFT). Basic research suggests that some class I drugs may have deleterious effects by raising defibrillation energy requirements. Evaluation of this problem in man has been limited to reports of patients who were more difficult to cardiovert or defibrillate after treatment with amiodarone and class IC agents. In the present report, mexiletine appeared to be the probable cause of an important elevation of DFT in a patient undergoing replacement of a malfunctioning automatic implantable cardioverter/defibrillator (AICD). This report and the accompanying literature review suggest that more information at both the basic and clinical levels is required. Retesting of device efficacy in terminating induced arrhythmia in the laboratory appears prudent in patients who require antiarrhythmic drug therapy subsequent to AICD implantation.     

Transseptal Defibrillation Is Superior for Transvenous Defibrillation

The conventional electrode configuration of current internal defibrillation systems most commonly use superior vena caval (SVC) or combined SVC and subcutaneous (SC) electrodes as anode, and right ventricular apex (HVA) electrode as cathode. We have demonstrated earlier that the septal mass is important for defibrillation. The purpose of the present study was to compare a transseptal to a conventional electrode arrangement in the canine model. Three endocardial electrodes, 5 French EnGuard™ were positioned in RVA, SVC, and the right ventricular outflow (RVO) in eight dogs. A 5 French SC electrode was positioned in the fifth left intercostal space. RVA-RVO^-/SC⁺ (configuration 2) was compared to SVC-SC⁺/RVA^-(configuration 1). Defibrillation threshold testing was performed using asymmetrical biphasic shock, 6 msec⁺/2 msec^-. Probit fit was used to compare the results at 40%, 50%, 60%, and 90% probabilities, and the logistic regression analysis to estimate the impact of variables. Electrode configuration had the strongest predictive value. Configuration 2 was superior to configuration 1 (P = 0.0016). At any voltage settings the probability of success for configuration 2 was greater, and current less (P < 0.00005). The energy requirements were reduced by approximately 33% for configuration 2. There were no significant differences in impedance between the two configurations. We conclude that transseptal defibrillation is more effective because of the improved lead geometry and voltage gradient.     

Is group B streptococcal screening during pregnancy justified?

Summary. Twenty-eight per cent of women investigated during pregnancy were carriers of group B streptococci (GBS). The use of broth enrichment was the most significant factor in determining GBS carriage rates. GBS carriage decreased during pregnancy. Transmission of GBS from mother to baby was related to vaginal carriage but rectal carriage in pregnancy was the best predictor of maternal carriage at term. Rectal and vaginal swabs taken at 28 and 36 weeks correctly predicted 92% of intrapartum GBS carriage. Although accurate prediction of intrapartum GBS carriage is possible, mass screening for GBS in pregnancy is unlikely to be cost-effective in those countries with a low incidence of neonatal GBS sepsis.     

Electrode Surface Area Is An Important Variable for Defibrillation

Previous studies have established efficacy of transseptal defibrillation. The purpose of the present study was to evaluate the role of transvenous electrode surface area for defibrillation. Sixteen dogs were randomized to 8 French and 5 French EnGuard™ electrodes; 8 dogs in each group. The length of the defibrillation coils was identical for both, but the surface area was different due to differences in the electrode diameters. Defibrillation threshold (DFT) testing was performed using a biphasic shock waveform, 6 msec⁺/2 msec^-. Logistic regression analysis was used to determine if the probability of defibrillation adjusted for voltage, current, and energy was different for 8 French electrodes. Logistic regression analysis found significant differences between 8 French and 5 French electrodes, with less voltage (P < 0.005), current (P < 0.03), and energy (P < 0.001) required at any level of probability to defibrillate for 8 French electrodes. These results support the conclusion that the surface area for endocardial electrodes is a significant factor for defibrillation. Therefore, when designing endocardial electrodes a desirable objective of reducing the electrode size should be weighed against the need to minimize DFTs.     

Energy supplementation in the last trimester of pregnancy in East Java: I. Effect on birthweight

Summary. The effect of two levels of energy supplementation in the last trimester of pregnancy on birthweight was tested in a controlled randomized trial in three villages in Madura, East Java. The high and low energy supplements provided 1·95 MJ (465 kcal) and 218 kj (52 kcal) per day respectively. In the baseline period the home diet provided on average 6·28 MJ (1500 kcal) (SD 2·1 MJ (499 kcal)) and41g(SD 13 g) of protein. The mean birthweight was 2835 g and the rate of low birth-weight 12·2%. In the experimental period the home diet was better. The average intake ranged from 6·45 to 7·19 MJ (1541–1717 kcal) and 41·4–44·2 g per day, depending on the degree of compliance. Mean birth-weight increased by 100 g and the rate of low birthweight dropped to 9·5%. There was no difference between the high and low energy supplemented group as a whole, probably due to the masking effect of the better home diet in the experimental period. It is likely that a positive effect of energy supplementation on birthweight was restricted to the group of pregnant women with the lowest home dietary intake and/or a low prepregnant weight. In this community targeting of supplementation to lean seasons and/or to women with a low prepregnant weight may be cost-effective.