Root Membrane Concept: Shield the Socket-A Case Report

Edentulousness affects the mental health of most patients. Missing teeth in the anterior esthetic zones is a matter of concern, especially for young adults. Various replacement options such as fixed partial dentures, removable partial dentures, and dental implants are available to treat edentulousness. Dental implants have been a booming treatment option in modern-day dentistry as they more closely mimic the natural tooth. The most important criterion for placement of the implant in the esthetic zone is the conservation of alveolar bone, especially in the anterior region which is usually compromised due to tooth extraction or resorption of the ridge. The root membrane concept or the socket shield technique is a recently introduced concept in implant dentistry where a portion of the root acts as a shield to protect against alveolar bone resorption and maintain bone integrity, especially in the esthetic area. This case report describes the clinical management of fractured upper anterior teeth using a dental implant and the root membrane technique. Keywords: Anterior zone, Esthetics, Immediate implants, Implant, Missing teeth, Root membrane technique, Socket shield.

Incorporation of carbon-14 in the biosynthesis of the macrolide antibiotic, LL-F28249-alpha

A total of 76 mCi of 14C LL-F28249-alpha, nemadectin (1), having a specific activity of 35.2 microCi/mg was isolated from a fermentation using a mixture of approximately 600 mCi of 14C carboxyl labeled acetate, propionate and isobutyrate. Nemadectin was used to synthesize carbon-14 labeled moxidectin which is being developed as a highly efficient ectoparasitic anthelminth. The labeled positions were determined by 13C NMR analysis of 13C nemadectin which was obtained by similar incorporation of 13C carboxyl labeled acetate, propionate and isobutyrate.

Biosynthetic origin of the carbon skeleton and oxygen atoms of the LL-F28249 alpha, a potent antiparasitic macrolide

The biosynthesis of LL-F28249 alpha in a culture of Streptomyces cyaneogriseus has been studied using 13C, 14C and 18O labeled precursors. A complete 13C NMR spectrum of F28249 alpha has been assigned. Incorporation studies using 13C labeled precursors indicate that the carbon skeleton of F28249 alpha is derived from seven acetate, six propionate and one 2-methylpropionate units. The origin of the oxygen atoms of F28249 alpha has been examined by feeding [1-13C,18O2]acetate, [1-13C,18O2]propionate, [2-13C]acetate/18O2 and 18O2 separately to the fermentation culture and analyzing the resulting labeled LL-F28249 alpha samples by 13C NMR, electron impact MS and chemical ionization MS. Out of a total of eight oxygen atoms in LL-F28249 alpha, four oxygen atoms are derived from acetate, three from propionate and one from molecular oxygen.