Synthesis and Characterization of Specific Reverse Transcriptase Inhibitors for Mammalian LINE-1 Retrotransposons.

Retrotransposons are a type of transposable element (TE) that have amplified to astonishing numbers in mammalian genomes, comprising more than a third of the human and mouse genomes. Long interspersed element class 1 (LINE-1 or L1) retrotransposons are abundant and currently active retroelements in the human and mouse genomes. Similarly, long terminal repeat (LTR)-containing retrotransposons are abundant in both genomes, although only active in mice.

Enhancing effect of glucose microspheres in the viability of human mesenchymal stem cell suspensions for clinical administration.

Purpose: A critical limiting factor of cell therapy is the short life of the stem cells. In this study, glucose containing alginate microspheres were developed and characterized to provide a sustained release system prolonging the viability of human mesenchymal stem cells (hMSCs) in a suspension for clinical application.

Methods: The glucose microspheres were satisfactorily elaborated with alginate by emulsification/internal gelation method.

Bone speed of sound throughout lifetime assessed with quantitative ultrasound in a Mexican population.

The purpose of this study was to assess the bone speed of sound (SoS) through lifetime of a large Mexican population sample by determining the SoS from the radius and tibia using quantitative ultrasound (QUS). This is a cross-sectional evaluation of participants in the Mexican Health Workers Cohort Study. QUS measurements were performed using Sunlight Omnisense 8000P; Z- and T-scores were calculated for both sexes at the distal third of the radius and midshaft tibia, both on the nondominant side.

Epidemiology of osteoporosis in Mexico. Present and future directions.

This position paper has been written by a multidisciplinary group of experts appointed by the National Institutes of Health (NIH). Its aim is to present the state of the art of knowledge about osteoporosis in Mexico. A review of the scientific papers in Mexico and information about diagnostics tools and treatment is discussed along with some research recommendations for the future.

Synthesis of pentahydroxylated pyrrolizidines and indolizidines.

1,3-Dipolar cycloaddition reaction of nitrone 7 and chemo-enzymatically obtained alkenediols 12 and 13 has been used in the synthesis of pentahydroxylated pyrrolizidines (8 and 10) and indolizidines (9 and 11). The pyrrolizidinic and indolizidinic skeletons were built after internal n-alkylation of the suitably functionalized pyrroloisoxazolidine intermediates obtained by the necessary protecting group manipulations. This method expands the scope of cycloaddition reactions in the synthesis of new and highly polyhydroxylated sugar-like alkaloids.

Direct costs of osteoporosis and hip fracture: an analysis for the Mexican Social Insurance Health Care System.

Objective: To compare costs of diagnosis and annual treatment of osteoporosis and hip fracture between the Instituto Nacional de Rehabilitación (INR) and the protocol used by the Seguro Popular de Salud (SPSS).

Methods: Direct costs gathered in a prospective study with real cases at the INR are presented, and then this data is re-analyzed with the methodology and protocol for the SPSS to estimate the costs of those cases if treated with the SPSS protocol.

Results: Important differences were found in the cost of hip fracture: the SPSS estimates ($37,363.

Diastereoselective synthesis of quaternary alpha-amino acids from diketopiperazine templates.

Sequential enolate alkylations of (S)-N(1)-methyl-5-methoxy-6-isopropyl-3,6-dihydropyrazin-2-one and (S)-N(1)-p-methoxybenzyl-5-methoxy-6-isopropyl-3,6-dihydropyrazin-2-one proceed with excellent levels of diastereoselectivity (>90% de) affording quaternary alpha-amino acids in high enantiomeric excess (>98% ee) after deprotection and hydrolysis.

Asymmetric conjugate reductions with samarium diiodide: asymmetric synthesis of (2S,3R)- and (2S,3S)-[2-2H,3-2H]-leucine-(S)-phenylalanine dipeptides and (2S,3R)-[2-(2)H,3-2H]-phenylalanine methyl ester.

The highly diastereoselective samarium diiodide and D(2)O-promoted conjugate reduction of homochiral (E)- and (Z)-benzylidene and isobutylidene diketopiperazines (E)-5,7 and (Z)-6,8 has been demonstrated. This methodology allows the asymmetric synthesis of methyl (2S,3R)-dideuteriophenylalanine 27 in > or = 95% de and >98% ee, and (2S,3R)- or (2S,3S)-dideuterioleucine-(S)-phenylalanine dipeptides 37 and 38 in moderate de, 66% and 74% respectively. A mechanism is proposed to account for this process.

Diastereoselective conjugate reduction with samarium diiodide: asymmetric synthesis of methyl (2S,3R)-N-acetyl-2-amino-2,3-dideuterio-3-phenylpropionate.

A highly diastereoselective conjugate reduction using SmI2 and D2O has been demonstrated on a homochiral benzylidene diketopiperazine template, giving methyl (2S,3R)-N-acetyl-2-amino-2,3-dideuterio-3-phenylpropionate in 93% de and 90% ee after deprotection, hydrolysis and N-acetylation.