The effect of naloxone on the preoperative gastric volume and pH

The effect of 4 mg oral naloxone on preoperative gastric volume and pH of gastric aspirate was studied in a double-blind, randomized study. Twenty patients received 10 ml of naloxone (4 mg) mixed with 10 ml of orange juice, and 20 patients received 10 ml of isotonic saline mixed with 10 ml of orange juice, 2 h before surgery. Gastric content was obtained immediately after intubation of the trachea. No significant difference in gastric volume and pH of gastric aspirate was found between the two groups. It is concluded that naloxone does not affect gastric emptying and gastric acid secretion to a degree great enough to protect against aspiration of gastric contents into the lungs.     

Therapeutic advantage of high-affinity anticarcinoma radioimmunoconjugates.

The effect of the relative affinity (Ka) on the antitumor efficacy of monoclonal antibodies (MAbs) has been questioned. It has previously been shown in experimental models that the use of MAbs with higher relative Kas manifests itself in a higher percentage of injected dose of MAb bound to tumor. On the other hand, mathematical models have proposed that the use of higher affinity MAbs may be disadvantageous for antitumor effects, since higher Ka MAbs would bind more antigen and prevent penetration of MAb through tumor. To test this hypothesis, three MAbs reacting to the human pancarcinoma antigen TAG-72 were used as radioimmunoconjugates for therapeutic efficacy versus the LS-174T human colon carcinoma xenograft. MAbs B72.3, CC49, and CC83 have all been shown by depletion studies to react to the same molecule and to all react with overlapping epitopes. While the relative Ka of B72.3 is 2.5 x 10(9) M-1, the relative Kas of CC49 and CC83 are 16.2 and 27.7 x 10(9) M-1, respectively. Each MAb was radiolabeled with 131I, and each radioimmunoconjugate was assayed at five dose levels for therapeutic efficacy using the human xenograft model. The results of these studies demonstrate substantial therapeutic advantage of the higher affinity MAbs CC49 and CC83 versus B72.3 at every dose level. While 500 microCi of B72.3 were required to reduce tumor growth in only a minority of tumor-bearing animals, the use of the same amount or less of the radioimmunoconjugates of CC49 or CC83 resulted in strong antitumor effects in 80 to 100% of tumor-bearing animals. Thus, stronger antitumor effects were seen using as little as 2.5- to 3-fold less of the higher Ka immunoconjugates CC49 and CC83 as compared with B72.3. While we acknowledge the potential disadvantages of higher Ka MAbs in some situations, at least the experimental studies and model system described here show that a distinct therapeutic advantage exists with the use of higher affinity immunoconjugates.     

Smoking and female infertility: a systematic review and meta-analysis

The high prevalence of smoking among women in their reproductive years continues to be a matter of concern. The negative effects of smoking on general health are well known, but smoking may also affect fertility. The objective of the present study was to perform a systematic review of the literature to determine whether there is an association between smoking and risk of infertility in women of reproductive age, and to assess the size of this effect. In the 12 studies used for this meta- analysis, the overall value of the odds ratio (OR) for risk of infertility in women smokers versus non-smokers was 1.60 [95% confidence interval (CI) 1.34-1.91]. Studies of subfertile women undergoing in-vitro fertilization (IVF) treatment also show a reduction in fecundity among women smokers. A meta-analysis of nine studies found an OR of 0.66 (95% CI 0.49-0.88) for pregnancies per number of IVF- treated cycles in smokers versus non-smokers. Despite the potential limitations of meta-analyses of observational studies, the evidence presented in this review is compelling because of the consistency of effect across different study designs, sample size and types of outcome. However, continued reassurance is needed that the calculated overall effect is not in fact due to confounding variables.