Extensive X-linked adaptive evolution in central chimpanzees

Surveying genome-wide coding variation within and among species gives unprecedented power to study the genetics of adaptation, in particular the proportion of amino acid substitutions fixed by positive selection. Additionally, contrasting the autosomes and the X chromosome holds information on the dominance of beneficial (adaptive) and deleterious mutations. Here we capture and sequence the complete exomes of 12 chimpanzees and present the largest set of protein-coding polymorphism to date. We report extensive adaptive evolution specifically targeting the X chromosome of chimpanzees with as much as 30% of all amino acid replacements being adaptive. Adaptive evolution is barely detectable on the autosomes except for a few striking cases of recent selective sweeps associated with immunity gene clusters. We also find much stronger purifying selection than observed in humans, and in contrast to humans, we find that purifying selection is stronger on the X chromosome than on the autosomes in chimpanzees. We therefore conclude that most adaptive mutations are recessive. We also document dramatically reduced synonymous diversity in the chimpanzee X chromosome relative to autosomes and stronger purifying selection than for the human X chromosome. If similar processes were operating in the human-chimpanzee ancestor as in central chimpanzees today, our results therefore provide an explanation for the much-discussed reduction in the human-chimpanzee divergence at the X chromosome.     

Low-density lipoprotein receptor overexpression enhances the rate of brain-to-blood Aβ clearance in a mouse model of β-amyloidosis

The apolipoprotein E (APOE)-ε4 allele is the strongest genetic risk factor for late-onset, sporadic Alzheimer''s disease, likely increasing risk by altering amyloid-β (Aβ) accumulation. We recently demonstrated that the low-density lipoprotein receptor (LDLR) is a major apoE receptor in the brain that strongly regulates amyloid plaque deposition. In the current study, we sought to understand the mechanism by which LDLR regulates Aβ accumulation by altering Aβ clearance from brain interstitial fluid. We hypothesized that increasing LDLR levels enhances blood–brain barrier-mediated Aβ clearance, thus leading to reduced Aβ accumulation. Using the brain Aβ efflux index method, we found that blood–brain barrier-mediated clearance of exogenously administered Aβ is enhanced with LDLR overexpression. We next developed a method to directly assess the elimination of centrally derived, endogenous Aβ into the plasma of mice using an anti-Aβ antibody that prevents degradation of plasma Aβ, allowing its rate of appearance from the brain to be measured. Using this plasma Aβ accumulation technique, we found that LDLR overexpression enhances brain-to-blood Aβ transport. Together, our results suggest a unique mechanism by which LDLR regulates brain-to-blood Aβ clearance, which may serve as a useful therapeutic avenue in targeting Aβ clearance from the brain.     

Pharmacologic inhibition of mTOR antagonizes the cytotoxic activity of pemetrexed in non-small cell lung cancer

Purpose  

Pemetrexed, an inhibitor of thymidylate synthase (TS) and additional folate-dependent enzymes, is clinically active in patients suffering from “non-squamous” non-small cell lung cancer (NSCLC). High expression of TS has been implied as biomarker predictive of resistance to pemetrexed. Against this background, we studied whether inhibition of mTOR could lower expression of TS and thus sensitize NSCLC cells to pemetrexed.     

The Korean Medication Algorithm for Major Depressive Disorder (KMA-MDD): Report of the Korean Society of Depressive and Bipolar Disorders

Objective. There are many differences in biological characteristics, clinical situations, and medical insurance systems with ethnic groups or countries. The Korean Society of Depressive and Bipolar Disorders decided to develop a Korean treatment algorithm for major depressive disorder. Methods. The Korean Medication Algorithm Project for Major Depressive Disorder (KMAP-MDD) was designed with the following principles: (1) to be an ideal algorithm, (2) to be a Korean algorithm, (3) to be a medication algorithm, (4) to be an evidence-based and formal consensus algorithm. After collecting and reviewing many literature citations and reports by evidence-based rule, we constructed a survey questionnaire for formal consensus of Korean experts. By employing panels of experts to review the evidence and survey results thoroughly, we used evidence-based algorithm development as a component of a formal consensus development process. Results. We developed two algorithms for the KMA-MDD: one for major depressive disorder without psychotic feature and the other for major depressive disorder with psychotic features. Clinical guidelines for the implementation of KMA-MDD were also developed. The KMA-MDD provides specific treatment strategies for each stage. Conclusions. The KMA-MDD is the first Korean algorithm for treatment of major depressive disorder. It is based on evidence which supports the efficacy of each treatment, and it has obtained the consensus of Korean experts. We hope that the KMA-MDD will be good practical tool for clinicians who treat major depressive disorder in Korea.     

Visuoconstructional Abilities in Cognitively Healthy Illiterate Turkish Immigrants: A Quantitative and Qualitative Investigation

Assessment of visuospatial function is an integral part of most neuropsychological assessments and is frequently assessed by visuoconstructional tests. A significant impact of limited schooling and illiteracy has been found on numerous neuropsychological tests and it can be difficult to interpret test results from illiterate individuals. In this study, quantitative and qualitative aspects of performance of elderly cognitively healthy illiterate and literate Turkish immigrants were compared on five commonly used visuoconstructional tests. Significantly poorer performances of illiterate compared to literate subjects were found in copying of two- and three-dimensional geometric designs, and in Clock Drawing Test performance. A systematic qualitative analysis found lacking three-dimensionality, “curved angles”, omissions, distorted relation between elements, and spatial disorganization to be common error types in illiterate subjects. Performances were not found to be influenced by duration of residence in Denmark or level of acculturation. The results warrant caution in the interpretation of visuoconstructional test performances in illiterate subjects, as they can easily be misinterpreted as signs of cognitive dysfunction.