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We report herein a novel series of difluoropiperidine acetic acids as modulators of gamma-secretase. Synthesis of 2-aryl-3,3-difluoropiperidine analogs was facilitated by a unique and selective beta-difluorination with Selectfluor. Compounds 1f and 2c were selected for in vivo assessment and demonstrated selective lowering of Abeta42 in a genetically engineered mouse model of APP processing. Moreover, in a 7-day safety study, rats treated orally with compound 1f (250mg/kg per day, AUC(0-24)=2100microMh) did not exhibit Notch-related effects.

Background. In humans, Helicobacter pylori is known to colonize the stomach and to induce persistent gastritis; selected reports also suggest it causes extragastric disease, including hepatitis. H. pylori and a novel urease-negative Helicobacter sp. induce gastritis and typhlocolitis, respectively, when inoculated orally into mice. Experimental typhlocolitis and hepatitis have been caused by intraperitoneal (IP) injection of H. hepaticus, H. bilis, and the novel Helicobacter spp. However, the route by which IP-inoculated organisms localize to specific areas of the gastrointestinal system is unknown. Materials and Methods. To determine whether Helicobacter spp. can be isolated from blood, can preferentially colonize specific tissues, and can cause pathological changes, we inoculated 6-week-old outbred mice orally or intraperitoneally with H. pylori or a novel Helicobacter sp. Results. When these mice were inoculated by the IP route, H. pylori was cultured from lungs, spleen, liver, cecum, and stomach on day 1 after inoculation, from liver and stomach mucosa on day 3 after inoculation, and from the stomach on day 30 after inoculation, suggesting preferential colonization of the stomach. After inoculation by the IP route, the novel intestinal Helicobacter sp. was cultured from the blood, lungs, spleen, liver, kidneys, cecum, and feces but not from stomach mucosa on day 1 after inoculation. By day 30 after inoculation, the novel Helicobacter sp. was cultured from cecum and feces only, suggesting that it had preferentially colonized the lower bowel. By the IP route, the novel Helicobacter sp. induced hepatitis that persisted for 30 days after inoculation. Though mice inoculated intraperitoneally with H. pylori developed an acute hepatitis, the liver lesion began to resolve 30 days after inoculation. Mice inoculated orally with either H. pylori or the novel Helicobacter sp. did not have hepatitis on day 30 after inoculation but developed 100% colonization of stomach and cecum, respectively. Conclusion. The isolation of H. pylori and the novel Helicobacter sp. from multiple tissues infers that a transient helicobacter bacteremia occurs when Helicobacter spp. are injected intraperitoneally, but organisms are cleared rapidly from nontarget tissues and preferentially colonize specific regions of the gastrointestinal tract.

Malignant hyperthermia-susceptible (MHS) pigs homozygous for the Cys615 ryanodine receptor allele demonstrate altered sarcoplasmic reticulum (SR) ryanodine binding and Ca2+ release channel regulatory properties when compared with normal pigs homozygous for the Arg615 allele. While solubilized in 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, the purified MHS and normal ryanodine receptors had a similar dissociation constant (Kd) for ryanodine, maximum binding, and Ca2+ concentration for half-maximal stimulation and inhibition of ryanodine binding (Ca2+(0.5)); however, after reconstitution into proteoliposomes, the purified MHS and normal receptors had Kd values for ryanodine of 75 and 150 nM, respectively, which were significantly different. The purified MHS and normal porcine ryanodine receptors also had similar single-channel Cs+ conductance, optimal cis-Ca2+ for channel opening, and cis-Ca2+(0.5) for channel activation. Significantly, at inactivating levels of cis-Ca2+ (> 0.1 mM), MHS channels had a greater open probability, a higher cis-Ca2+(0.5) for inhibition of channel opening (250 vs. 75 microM for MHS and normal, respectively), longer mean open times, and shorter mean closed times than did normal channels. We conclude that the mutation at residue 615 causes a detectable alteration in ryanodine receptor/Ca2+ channel activity and thus may represent the primary defect responsible for the altered SR Ca2+ regulation characteristic of MHS porcine muscle.