In the absence of external stimuli or task demands, correlations in spontaneous brain activity (functional connectivity) reflect patterns of anatomical connectivity. Hence, resting-state functional ...connectivity has been used as a proxy measure for structural connectivity and as a biomarker for brain changes in disease. To relate changes in functional connectivity to physiological changes in the brain, it is important to understand how correlations in functional connectivity depend on the physical integrity of brain tissue. The causal nature of this relationship has been called into question by patient data suggesting that decreased structural connectivity does not necessarily lead to decreased functional connectivity. Here we provide evidence for a causal but complex relationship between structural connectivity and functional connectivity: we tested interhemispheric functional connectivity before and after corpus callosum section in rhesus monkeys. We found that forebrain commissurotomy severely reduced interhemispheric functional connectivity, but surprisingly, this effect was greatly mitigated if the anterior commissure was left intact. Furthermore, intact structural connections increased their functional connectivity in line with the hypothesis that the inputs to each node are normalized. We conclude that functional connectivity is likely driven by corticocortical white matter connections but with complex network interactions such that a near-normal pattern of functional connectivity can be maintained by just a few indirect structural connections. These surprising results highlight the importance of network-level interactions in functional connectivity and may cast light on various paradoxical findings concerning changes in functional connectivity in disease states.
Further research into medical student attitudes towards older people is important, and requires accurate and detailed evaluative methodology. The two objectives for this paper are: (1) From the ...literature, to critically review instruments of measure for medical student attitudes towards older people, and (2) To recommend the most appropriate quantitative instrument for future research into medical student attitudes towards older people.
A SCOPUS and Ovid cross search was performed using the keywords Attitude and medical student and aged or older or elderly. This search was supplemented by manual searching, guided by citations in articles identified by the initial literature search, using the SCOPUS and PubMed databases. International studies quantifying medical student attitudes have demonstrated neutral to positive attitudes towards older people, using various instruments. The most commonly used instruments are the Ageing Semantic Differential (ASD) and the University of California Los Angeles Geriatric Attitudes Scale, with several other measures occasionally used. All instruments used to date have inherent weaknesses. A reliable and valid instrument with which to quantify modern medical student attitudes towards older people has not yet been developed. Adaptation of the ASD for contemporary usage is recommended.
Anatomical and functional studies of the prefrontal cortex (PFC) have identified multiple PFC subregions. We argue that the PFC is involved in cognitive functions exceeding the sum of specific ...functions attributed to its subregions. These can be revealed either by lesions of the whole PFC, or more specifically by selective disconnection of the PFC from certain types of information (for example, visual) allowing the investigation of PFC function in toto . Recent studies in macaque monkeys using the latter approach lead to a second conclusion: that the PFC, as a whole, could be fundamentally specialized for representing events that are extended in time. The representation of temporally complex events might underlie PFC involvement in general intelligence, decision-making, and executive function.
Inflammatory cross talk between perivascular adipose tissue and the blood vessel wall has been proposed to contribute to the pathogenesis of atherosclerosis. We previously reported that human ...perivascular (PV) adipocytes exhibit a proinflammatory phenotype and less adipogenic differentiation than do subcutaneous (SQ) adipocytes. To gain a global view of the genomic basis of biologic differences between PV and SQ adipocytes, we performed genome-wide expression analyses to identify differentially expressed genes between adipocytes derived from human SQ vs. PV adipose tissues. Although >90% of well-expressed genes were similarly regulated, we identified a signature of 307 differentially expressed genes that were highly enriched for functions associated with the regulation of angiogenesis, vascular morphology, inflammation, and blood clotting. Of the 156 PV upregulated genes, 59 associate with angiogenesis, vascular biology, or inflammation, noteworthy of which include TNFRSF11B (osteoprotegerin), PLAT, TGFB1, THBS2, HIF1A, GATA6, and SERPINE1. Of 166 PV downregulated genes, 21 associated with vascular biology and inflammation, including ANGPT1, ANGPTL1, and VEGFC. Consistent with the emergent hypothesis that PV adipocytes differentially regulate angiogenesis and inflammation, cell culture-derived adipocyte-conditioned media from PV adipocytes strongly enhanced endothelial cell tubulogenesis and monocyte migration compared with media from SQ adipocytes. These findings demonstrate that PV adipocytes have the potential to significantly modulate vascular inflammatory crosstalk in the setting of atherosclerosis by their ability to signal to both endothelial and inflammatory cells.
This phase III, randomized, open-label, multicenter study compared the overall survival associated with irinotecan plus gemcitabine (IRINOGEM) versus gemcitabine monotherapy (GEM) in patients with ...chemotherapy-naive, locally advanced or metastatic pancreatic cancer.
IRINOGEM patients received starting doses of gemcitabine 1,000 mg/m2 and irinotecan 100 mg/m2 given weekly for 2 weeks every 3-week cycle. GEM patients received gemcitabine 1,000 mg/m2 weekly for 7 of 8 weeks (induction) and then weekly for 3 of 4 weeks. The primary end point of the trial was survival. Secondary end points included tumor response, time to tumor progression (TTP), changes in CA 19-9, and safety.
In each arm, 180 randomly assigned patients comprised the intent-to-treat population evaluated for efficacy; 173 IRINOGEM and 169 GEM patients were treated. Median survival times were 6.3 months for IRINOGEM (95% CI, 4.7 to 7.5 months) and 6.6 months for GEM (95% CI, 5.2 to 7.8 months; log-rank P =.789). Tumor response rates were 16.1% (95% CI, 11.1% to 22.3%) for IRINOGEM and 4.4% (95% CI, 1.9% to 8.6%) for GEM (chi2 P <.001). Median TTP was 3.5 months for IRINOGEM versus 3.0 months for GEM (log-rank P =.352). However, subset analyses in patients with locally advanced disease suggested a TTP advantage with IRINOGEM versus GEM (median, 7.7 v 3.9 months). CA 19-9 progression was positively correlated with tumor progression. The incidence of grade 3 diarrhea was higher in the IRINOGEM group but grade 3 to 4 hematologic toxicities and quality-of-life outcomes were similar.
IRINOGEM safely improved the tumor response rate compared with GEM but did not alter overall survival.
It is commonly thought that human genetic diversity in non-African populations was shaped primarily by an out-of-Africa dispersal 50-100 thousand yr ago (kya). Here, we present a study of 456 ...geographically diverse high-coverage Y chromosome sequences, including 299 newly reported samples. Applying ancient DNA calibration, we date the Y-chromosomal most recent common ancestor (MRCA) in Africa at 254 (95% CI 192-307) kya and detect a cluster of major non-African founder haplogroups in a narrow time interval at 47-52 kya, consistent with a rapid initial colonization model of Eurasia and Oceania after the out-of-Africa bottleneck. In contrast to demographic reconstructions based on mtDNA, we infer a second strong bottleneck in Y-chromosome lineages dating to the last 10 ky. We hypothesize that this bottleneck is caused by cultural changes affecting variance of reproductive success among males.
Transcranial Doppler is a widely used noninvasive technique for assessing cerebral artery blood flow. All previous high altitude studies assessing cerebral blood flow (CBF) in the field that have ...used Doppler to measure arterial blood velocity have assumed vessel diameter to not alter. Here, we report two studies that demonstrate this is not the case. First, we report the highest recorded study of CBF (7,950 m on Everest) and demonstrate that above 5,300 m, middle cerebral artery (MCA) diameter increases (n = 24 at 5,300 m, 14 at 6,400 m, and 5 at 7,950 m). Mean MCA diameter at sea level was 5.30 mm, at 5,300 m was 5.23 mm, at 6,400 m was 6.66 mm, and at 7,950 m was 9.34 mm (P<0.001 for change between 5,300 and 7,950 m). The dilatation at 7,950 m reversed with oxygen. Second, we confirm this dilatation by demonstrating the same effect (and correlating it with ultrasound) during hypoxia (FiO2 = 12% for 3 hours) in a 3-T magnetic resonance imaging study at sea level (n = 7). From these results, we conclude that it cannot be assumed that cerebral artery diameter is constant, especially during alterations of inspired oxygen partial pressure, and that transcranial 2D ultrasound is a technique that can be used at the bedside or in the remote setting to assess MCA caliber.
High-coverage whole-genome sequence studies have so far focused on a limited number of geographically restricted populations, or been targeted at specific diseases, such as cancer. Nevertheless, the ...availability of high-resolution genomic data has led to the development of new methodologies for inferring population history and refuelled the debate on the mutation rate in humans. Here we present the Estonian Biocentre Human Genome Diversity Panel (EGDP), a dataset of 483 high-coverage human genomes from 148 populations worldwide, including 379 new genomes from 125 populations, which we group into diversity and selection sets. We analyse this dataset to refine estimates of continent-wide patterns of heterozygosity, long- and short-distance gene flow, archaic admixture, and changes in effective population size through time as well as for signals of positive or balancing selection. We find a genetic signature in present-day Papuans that suggests that at least 2% of their genome originates from an early and largely extinct expansion of anatomically modern humans (AMHs) out of Africa. Together with evidence from the western Asian fossil record, and admixture between AMHs and Neanderthals predating the main Eurasian expansion, our results contribute to the mounting evidence for the presence of AMHs out of Africa earlier than 75,000 years ago.
E3 ligases mediate the covalent attachment of ubiquitin to target proteins thereby enabling ubiquitin-dependent signaling. Unraveling how E3 ligases are regulated is important because miscontrolled ...ubiquitylation can lead to disease. Cellular inhibitor of apoptosis (cIAP) proteins are E3 ligases that modulate diverse biological processes such as cell survival, proliferation, and migration. Here, we have solved the structure of the caspase recruitment domain (CARD) of cIAP1 and identified that it is required for cIAP1 autoregulation. We demonstrate that the CARD inhibits activation of cIAP1's E3 activity by preventing RING dimerization, E2 binding, and E2 activation. Moreover, we show that the CARD is required to suppress cell proliferation and migration. Further, CARD-mediated autoregulation is also necessary to maximally suppress caspase-8-dependent apoptosis and vascular tree degeneration in vivo. Taken together, our data reveal mechanisms by which the E3 ligase activity of cIAP1 is controlled, and how its deregulation impacts on cell proliferation, migration and cell survival.
Display omitted
► The CARD of cIAP1 suppresses activation of cIAP1's E3 ligase activity ► The CARD prevents RING dimerization, E2 binding, and E2 activation ► CARD-mutant cIAP1 is more active in promoting cell proliferation and migration ► CARD-mediated autoinhibition protects from vascular degeneration
PDF
