To B or not to B: is tylosis B truly benign? Two North American genealogies.

Tylosis is a rare, autosomal dominant syndrome presenting with hyperkeratosis of the palms and soles of the feet. Two types have been identified. Late onset tylosis (type A) is reported to be associated with a high incidence of esophageal carcinoma, whereas early onset tylosis (type B) appears to be a benign disorder. This distinction has significant implications for surveillance and prognosis. We report two families exhibiting early onset type B tylosis, spanning five and seven generations, respectively, and believe these to be the first two extensive genealogies of tylosis type B reported in North America. They serve to verify the features of type B tylosis and its benign prognosis. The world literature is reviewed and clinical relevance is discussed. Recommendations for follow-up of afflicted individuals are proposed.

Benzodiazepine receptor-mediated behavioral effects of nitrous oxide in the rat social interaction test.

The present study was conducted to ascertain whether an anxiolytic effect of nitrous oxide was demonstrable in rats using the social interaction test and whether this drug effect might be mediated by benzodiazepine receptors. Compared to behavior of vehicle-pretreated, room air-exposed rats, rat pairs exposed to nitrous oxide showed a generally inverted U-shaped dose-response curve with the maximum increase in social interaction encounters occurring at 25% and significant increase in time of active social interaction at 15-35%; higher concentrations produced a sedative effect that reduced social interaction. Treatment with 5.0 mg/kg of the anxiolytic benzodiazepine chlordiazepoxide also increased social interaction. Pretreatment with 10 mg/kg of the benzodiazepine receptor blocker flumazenil, which alone had no effect, significantly antagonized the social interaction-increasing effects of both nitrous oxide and chlordiazepoxide. In summary, these findings suggest that nitrous oxide produces a flumazenil-sensitive effect comparable to that of chlordiazepoxide and implicate central benzodiazepine mechanisms in mediation of the anxiolytic effect of nitrous oxide.

Naltrexone-sensitive analgesia following exposure of mice to 2450-MHz radiofrequency radiation.

To determine whether exposure to radiofrequency radiation (RFR) would induce sufficient thermal stress to activate endogenous opioid mechanisms, male Swiss Webster mice were exposed to 10, 15, and 20 mW/cm2 RFR in a 2450-MHz waveguide system for 10 min at specific absorption rates (SARs) of 23.7, 34.6, and 45.5 W/kg, respectively, then tested in the abdominal constriction paradigm. Confinement in the RFR exposure chamber alone did not appreciably alter body temperature but did appear to induce a stress-associated analgesia that was not blocked by naltrexone. Exposure of confined mice to RFR raised body temperature and further increased analgesia in an SAR-dependent manner. The high SAR-induced analgesia, but not the hyperthermia, was blocked by naltrexone. These findings suggest that 1) RFR produces SAR-dependent hyperthermia and analgesia, and 2) RFR-induced analgesia is mediated by opioid mechanisms while confinement-induced analgesia involves nonopioid mechanisms.