Y染色体或将在进化中消失

美国宾夕法尼亚州立大学的2位科学家在性染色体进化变异机制的研究上取得进展。研究发现,Y染色体比X染色体的演化速率快得多,这将导致Y染色体上的基因急剧丢失,如此,Y染色体将会完全消失,人类的传宗接代将受威胁。     

Early recognition of heart failure in patients with diabetes type 2 in primary care. A prospective diagnostic efficiency study. (UHFO-DM2)

Background  

We hypothesize that the prevalence of unknown heart failure in diabetic patients aged 60 years and over is relatively high (15% or more) and that a cost-effective strategy can be developed to detect heart failure in these patients. The strategy is expected to include some signs and symptoms (such as dyspnoea, orthopnoea, pulmonary crepitations and laterally displaced apical beat), natriuretic peptide measurements (Amino-terminal B-type natriuretic peptide) and possibly electrocardiography. In a subset of patients straightforward echocardiography may show to be cost-effective. With information from our study the detection of previously unknown heart failure in diabetic patients could be improved and enable the physician to initiate beneficial morbidity and mortality reducing heart failure treatment more timely.     

Mapping the relationship between cortical convolution and intelligence: effects of gender

The pronounced convolution of the human cortex may be a morphological substrate that supports some of our species' most distinctive cognitive abilities. Therefore, individual intelligence within humans might be modulated by the degree of folding in certain cortical regions. We applied advanced methods to analyze cortical convolution at high spatial resolution and correlated those measurements with intelligence quotients. Within a large sample of healthy adult subjects (n = 65), we detected the most prominent correlations in the left medial hemisphere. More specifically, intelligence scores were positively associated with the degree of folding in the temporo-occipital lobe, particularly in the outermost section of the posterior cingulate gyrus (retrosplenial areas). Thus, this region might be an important contributor toward individual intelligence, either via modulating pathways to (pre)frontal regions or by serving as a location for the convergence of information. Prominent gender differences within the right frontal cortex were observed; females showed uncorrected significant positive correlations and males showed a nonsignificant trend toward negative correlations. It is possible that formerly described gender differences in regional convolution are associated with differences in the underlying architecture. This might lead to the development of sexually dimorphic information processing strategies and affect the relationship between intelligence and cortical convolution.     

Regional patterns and clinical correlates of basal ganglia morphology in non-medicated schizophrenia

Although structural changes of the basal ganglia are widely implicated in schizophrenia, prior findings in chronically medicated patients show that these changes relate to particular antipsychotic treatments. In unmedicated schizophrenia, local alterations in morphological parameters and their relationships with clinical measures remain unknown. Novel surface-based anatomical modelling methods were applied to magnetic resonance imaging data to examine regional changes in the shape and volume of the caudate, the putamen and the nucleus accumbens in 21 patients (19 males/2 females; mean age=30.7+/-7.3) who were either antipsychotic-na?ve or antipsychotic-free for at least 1 year and 21 healthy comparison subjects (19 males/2 females; mean age=31.1+/-8.2). Clinical relationships of striatal morphology were based on exploratory analyses. Left and right global putamen volumes were significantly smaller in patients than controls; no significant global volume effects were observed for the caudate and the nucleus accumbens. However, surface deformation mapping results showed localized volume changes prominent bilaterally in medial/lateral anterior regions of the caudate, as well as in anterior and midposterior regions of the putamen, pronounced on the medial surface. A significant positive correlation was observed between right anterior putamen surface contractions and affective flattening, a core negative symptom of schizophrenia. The diagnostic effects of local surface deformations mostly pronounced in the associative striatum, as well as the correlation between anterior putamen morphology and affective flattening in unmedicated schizophrenia suggest disease-specific neuroanatomical abnormalities and distinct cortical-striatal dysconnectivity patterns relevant to altered executive control, motor planning, along with abnormalities of emotional processing.     

Mapping cerebellar degeneration in HIV/AIDS

Progressive brain atrophy in HIV/AIDS is associated with impaired psychomotor performance, perhaps partly reflecting cerebellar degeneration; yet little is known about how HIV/AIDS affects the cerebellum. We visualized the three-dimensional profile of atrophy in 19 HIV-positive patients (age: 42.9+/-8.3 years) versus 15 healthy controls (age: 38.5+/-12.0 years). We localized consistent patterns of subregional atrophy with an image analysis method that automatically deforms each patient's scan, in three dimensions, to match a reference image. Atrophy was greatest in the posterior cerebellar vermis (14.9% deficit) and correlated with depression severity (P=0.009, corrected), but not with dementia, alcohol/substance abuse, CD4+T-cell counts, or viral load. Profound cerebellar deficits in HIV/AIDS (P=0.007, corrected) were associated with depression, suggesting a surrogate disease marker for antiretroviral trials.     

Commotio Cordis Presenting as a Temporary Complete Atrioventricular Block in a 2-Year-Old Girl With Congenitally Corrected Transposition of the great Arteries

This report describes a 2-year-old girl with congenitally corrected transposition of the great arteries (ccTGA) who presented with transient complete atrioventricular (AV) block after a mild chest blow. Running around the house with her older sister, she fell to the floor. Her sister also fell and landed on her. The girl became cyanotic and pale and experienced a transient loss of consciousness. At arrival to the emergency department, she had regained consciousness, but she remained pale. An electrocardiogram (ECG) demonstrated complete AV block with a heart rate of 78 beats per minute (bpm). The ECG after admission showed a Wenckebach-type second-degree AV block. Day 2 after admission, a 12-lead ECG showed significant ST and T-wave abnormalities in the precordial leads, but the girl had no chest pain and a normal physical examination. Echocardiography demonstrated normal contractility of the systemic right ventricle. The first-degree AV block and the ST and T-wave abnormalities on the 12-lead ECG improved gradually without abnormal Q-waves. This is the first report of ccTGA in which a transient complete AV block naturally recovered after a presentation with commotio cordis.     

Automated ventricular mapping with multi-atlas fluid image alignment reveals genetic effects in Alzheimer's disease

We developed and validated a new method to create automated 3D parametric surface models of the lateral ventricles in brain MRI scans, providing an efficient approach to monitor degenerative disease in clinical studies and drug trials. First, we used a set of parameterized surfaces to represent the ventricles in four subjects' manually labeled brain MRI scans (atlases). We fluidly registered each atlas and mesh model to MRIs from 17 Alzheimer's disease (AD) patients and 13 age- and gender-matched healthy elderly control subjects, and 18 asymptomatic ApoE4-carriers and 18 age- and gender-matched non-carriers. We examined genotyped healthy subjects with the goal of detecting subtle effects of a gene that confers heightened risk for Alzheimer's disease. We averaged the meshes extracted for each 3D MR data set, and combined the automated segmentations with a radial mapping approach to localize ventricular shape differences in patients. Validation experiments comparing automated and expert manual segmentations showed that (1) the Hausdorff labeling error rapidly decreased, and (2) the power to detect disease- and gene-related alterations improved, as the number of atlases, N, was increased from 1 to 9. In surface-based statistical maps, we detected more widespread and intense anatomical deficits as we increased the number of atlases. We formulated a statistical stopping criterion to determine the optimal number of atlases to use. Healthy ApoE4-carriers and those with AD showed local ventricular abnormalities. This high-throughput method for morphometric studies further motivates the combination of genetic and neuroimaging strategies in predicting AD progression and treatment response.     

Construction of a 3D probabilistic atlas of human cortical structures

We describe the construction of a digital brain atlas composed of data from manually delineated MRI data. A total of 56 structures were labeled in MRI of 40 healthy, normal volunteers. This labeling was performed according to a set of protocols developed for this project. Pairs of raters were assigned to each structure and trained on the protocol for that structure. Each rater pair was tested for concordance on 6 of the 40 brains; once they had achieved reliability standards, they divided the task of delineating the remaining 34 brains. The data were then spatially normalized to well-known templates using 3 popular algorithms: AIR5.2.5's nonlinear warp (Woods et al., 1998) paired with the ICBM452 Warp 5 atlas (Rex et al., 2003), FSL's FLIRT (Smith et al., 2004) was paired with its own template, a skull-stripped version of the ICBM152 T1 average; and SPM5's unified segmentation method (Ashburner and Friston, 2005) was paired with its canonical brain, the whole head ICBM152 T1 average. We thus produced 3 variants of our atlas, where each was constructed from 40 representative samples of a data processing stream that one might use for analysis. For each normalization algorithm, the individual structure delineations were then resampled according to the computed transformations. We next computed averages at each voxel location to estimate the probability of that voxel belonging to each of the 56 structures. Each version of the atlas contains, for every voxel, probability densities for each region, thus providing a resource for automated probabilistic labeling of external data types registered into standard spaces; we also computed average intensity images and tissue density maps based on the three methods and target spaces. These atlases will serve as a resource for diverse applications including meta-analysis of functional and structural imaging data and other bioinformatics applications where display of arbitrary labels in probabilistically defined anatomic space will facilitate both knowledge-based development and visualization of findings from multiple disciplines.