Retention of dental sealants placed on sound teeth and incipient caries lesions as part of a service‐learning programme in rural areas in Mexico

International Journal of Paediatric Dentistry 2012; 22: 451–458 Background. Dental sealants are an effective treatment for the prevention and management of caries. Objective. To determine the retention of sealants placed in a rural setting in Mexico as part of an international service‐learning (ISL) programme and to determine associations between dental sealant’s retention and caries diagnosis at the time of sealant placement. Methods. Children aged 6–15 were examined for dental caries, received sealants by dental students as part of an ISL programme, and were re‐examined 4, 2, or 1 years after placement to assess sealant survival. Sealants were placed on permanent sound surfaces and enamel caries lesions [International Caries Assessment and Detection System (ICDAS) criteria]. Sealant survival was explored using Cochran–Mantel–Haenszel tests and multivariate prediction models. Results. 219 (46%) of 478 (mean age = 10.53 SD = 5.11) children who had received sealants returned for a recall examination (mean age = 10.89 SD = 3.11). After 1–4 years, 96.4% to 60.6% of the sealants placed on sound teeth had survived, and for sealants placed on surfaces with enamel caries lesions (ICDAS 1–3), 94.2% to 55.6% had survived. Differences were not statistically significant. Conclusions. Sealants had survival rates comparable to those previously reported in the literature. Sealants placed on sound and enamel caries lesions had similar survival rates.     

Radiofrequency Catheter Ablation of Ventricular Tachycardia Guided by Nonsurgical Epicardial Mapping in Chronic Chagasic Heart Disease

We report a case of a 63-year-old women with Chagas'disease and recurrent, syncopal VT treated by RF catheter ablation in whom endocardial application of RF energy was guided by nonsurgical epicardial mapping. The procedure was undertaken in the electrophysiology laboratory under deep anesthesia. VT was interrupted after 2.4 seconds of application and rendered noninducible afterwards. Two weeks after the procedure, a distinct morphology VT was induced by programmed ventricular stimulation, and the patient was started on amiodarone, remaining asymptomatic 12 months after the procedure.     

Evaluation of Subchronic (13 Week), Reproductive, and in Vitro Genetic Toxicity Potential of 2-Ethylhexyl-2-cyano-3,3-diphenyl Acrylate (Octocrylene)

Use of 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate (Octocrylene)in commercial sunscreen products has increased considerablyin recent years. To support larger scale human exposure to thiscompound, additional toxicological information was needed inseveral key areas. The present studies evaluated subchronictoxicity, developmental toxicity, and in vitro genotoxic potentialof Octocrylene. In the subchronic study, male and female NewZealand white (NZW) rabbits treated topically with concentrationsof octocrylene up to 534 mg/kg/day for 13 weeks showed slightto moderate dose-dependent skin irritation that correlated positivelywith a mild depression in body weight gain. Lack of associatedhistopathologic or clinical hematology abnormalities suggestedthat the body weight effect probably reflected a nonspecificresponse to topical irritation. In percutaneous developmentaltoxicity studies, NZW does were treated topically with Octocryleneat levels up to 267 mg/kg/day on Days 6 through 18 of gestation.Body weight gain, food consumption, and all maternal, reproductive,and offspring parameters evaluated were comparable between Octocrylene-treatedand control animals. In the oral developmental toxicity assay,female CD-1 mice received oral doses of Octocrylene up to 1000mg/kg/day on Days 8–12 of gestation. No evidence of maternalor developmental toxicity was seen at any dose tested. Genotoxicitywas evaluated in vitro using the Chinese hamster ovary cellassay to assess clastogenicity and the mouse lymphoma cell assayto assess forward gene mutations. Octocrylene did not induceany significant increase in genotoxicity. This evaluation oftoxicological potential supports the use of Octocrylene as ahuman photoprotectant.     

Chemical synthesis and characterization of peptides and oligomeric proteins designed to form transmembrane ion channels

A strategy for the synthesis of peptides and oligomeric proteins designed to form transmembrane ion channels is described. A folding motif that exhibits a functional ionic pore encompasses amphipathic α-helices organized as a four-helix bundle around a central hydrophilic pore. The channel-forming activity of monomeric amphipathic peptides may be examined after reconstitution in lipid bilayers in which peptides self-assemble into conductive oligomers. The covalent attachment of channel-forming peptides to the lysine ε-amino groups of a template molecule (KKKPGKEKG) specifies oligomeric number and facilitates the study of ionic permeation and channel blockade. Here we describe detailed protocols for the total synthesis of peptides and template-assembled four-helix bundle proteins, exemplified with the sequence of M2δ (EKM-STAISVLLAQAVFLLLTSQR), considered involved in lining the pore of the nicotinic acetylcholine receptor channel. For comparison, the synthesis of a second four-helix bundle, T₄CaIVS3 with the sequence of predicted transmembrane segment S3 (DPWNVFDFLIVIGSIIDVILSE) of the fourth repeat of the l -type voltage-gated calcium channel, is included. Peptides and proteins are synthesized step-wise by solid-phase methods, purified by reversed-phase HPLC, and homogeneity ascertained by analytical HPLC, capillary zone electrophoresis, SDS/PAGE, amino acid analysis and sequencing. Optimization of synthetic procedures for hydrophobic molecules include reducing resin substitution to avoid steric hindrance and aggregation of the final product. Protocols for the preparation of the samples prior to HPLC purification as well as the conditions and columns required for successful purification are presented. The methods developed are generally applicable for the chemical synthesis, purification and characterization of amphipathic peptides and template directed helical bundle proteins.