The time scale of recombination rate evolution in great apes

We present three linkage-disequilibrium (LD)-based recombination maps generated using whole-genome sequence data from 10 Nigerian chimpanzees, 13 bonobos, and 15 western gorillas, collected as part of the Great Ape Genome Project (Prado-Martinez J, et al. 2013. Great ape genetic diversity and population history. Nature 499:471-475). We also identified species-specific recombination hotspots in each group using a modified LDhot framework, which greatly improves statistical power to detect hotspots at varying strengths. We show that fewer hotspots are shared among chimpanzee subspecies than within human populations, further narrowing the time scale of complete hotspot turnover. Further, using species-specific PRDM9 sequences to predict potential binding sites (PBS), we show higher predicted PRDM9 binding in recombination hotspots as compared to matched cold spot regions in multiple great ape species, including at least one chimpanzee subspecies. We found that correlations between broad-scale recombination rates decline more rapidly than nucleotide divergence between species. We also compared the skew of recombination rates at centromeres and telomeres between species and show a skew from chromosome means extending as far as 10-15Mb from chromosome ends. Further, we examined broad-scale recombination rate changes near a translocation in gorillas and found minimal differences as compared to other great ape species perhaps because the coordinates relative to the chromosome ends were unaffected. Finally, on the basis of multiple linear regression analysis, we found that various correlates of recombination rate persist throughout the African great apes including repeats, diversity, and divergence. Our study is the first to analyze within- And between-species genome-wide recombination rate variation in several close relatives

Determination of the total concentration of highly protein-bound drugs in plasma by on-line dialysis and column liquid chromatography: application to non-steroidal anti-inflammatory drugs.

The potential of on-line dialysis as a sample preparation procedure for compounds highly bound to plasma proteins is evaluated, using non-steroidal anti-inflammatory drugs as model compounds and column liquid chromatography as the separation technique. Different strategies to reduce the degree of drug-protein binding and so increase the analyte recovery are systematically explored and discussed: alteration of the conformation of the binding protein by changing the pH of the sample or by adding an organic solvent, addition of several displacing compounds and combinations of such approaches. A fully automated method is presented for the determination of ketoprofen, ibuprofen, flurbiprofen, fenoprofen and naproxen in human plasma, in which the absolute analyte recoveries are increased from 0-1% (untreated samples) to 40-65%. Relevant analytical data are given to demonstrate the reliability of the proposed procedure. © 1995

Collaborative study of an liquid chromatographic method for the determination of R-timolol and other related substances in S-timolol maleate

A collaborative study applying an enantiomeric liquid chromatographic (LC) method was carried out to determine the content of the enantiomeric impurity R-timolol and other related substances in three different S-timolol maleate samples. Eight laboratories, all located in Europe, participated in the study. The quantitative results obtained were used to estimate the uncertainty on the content of the different impurities. For that purpose, a set-up was adapted from the ISO guidelines 5725-2, which allowed the estimation of the different variances, i.e. the between-laboratories (s(laboratories)(2)), the between-days (s(days)(2)) and the between-replicates (s(replicates)(2)), The variances of repeatability (s(r)(2)) and reproducibility (s(R)(2)) were then calculated using the equations s(r)(2) = s(replicates)(2) and s(R)(2) = s(replicates)(2) + s(days)(2) + s(laboratories)(2). For the timolol impurities, it was found that the estimated uncertainty seem to be concentration-dependent. Since the LC method which combines the compendial ones for enantiomeric purity and related substances testing was applied to evaluate uncertainty in this collaborative study, it was shown how a laboratory can evaluate the uncertainty of its results when applying the method in the future. (c) 2005 Elsevier B.V. All rights reserved

High-Performance Liquid Chromatographic Analysis of Drugs of Abuse in Biologic Samples

Recently, drug abuse has become a serious social problem world wide. In Japan, methamphetamine (MP) is the most popular drug of abuse. In addition to MP, the use of 4,5-methylenedioxymethamphetamine (MDMA), called ecstacy, is rapidly increasing, especially among young people. The development of simple and convenient analytical methods for the analysis of these drugs of abuse is necessary for the prediction of and protection from human health risks. Many useful methods have been developed for qualification and quantification of drugs of abuse. Among these, gas chromatography with mass spectrometry (MS) and high-performance liquid chromatography with MS (HPLC-MS or LC-MS) or fluorescence (HPLC-FL) detection are widely used. As highly sensitive methods, precolumn or postcolumn derivatization methods are commonly utilized in HPLC. This review focuses on HPLC methods used for the practical analysis of drugs of abuse, mainly for amphetamine derivatives and MDMAs in biologic samples such as urine, blood, and hair