5,022 research outputs found
L1CAM binds ErbB receptors through Ig-like domains coupling cell adhesion and neuregulin signalling.
During nervous system development different cell-to-cell communication mechanisms operate in parallel guiding migrating neurons and growing axons to generate complex arrays of neural circuits. How such a system works in coordination is not well understood. Cross-regulatory interactions between different signalling pathways and redundancy between them can increase precision and fidelity of guidance systems. Immunoglobulin superfamily proteins of the NCAM and L1 families couple specific substrate recognition and cell adhesion with the activation of receptor tyrosine kinases. Thus it has been shown that L1CAM-mediated cell adhesion promotes the activation of the EGFR (erbB1) from Drosophila to humans. Here we explore the specificity of the molecular interaction between L1CAM and the erbB receptor family. We show that L1CAM binds physically erbB receptors in both heterologous systems and the mammalian developing brain. Different Ig-like domains located in the extracellular part of L1CAM can support this interaction. Interestingly, binding of L1CAM to erbB enhances its response to neuregulins. During development this may synergize with the activation of erbB receptors through L1CAM homophilic interactions, conferring diffusible neuregulins specificity for cells or axons that interact with the substrate through L1CAM
Synthesis of Propargylamines by Cross-Dehydrogenative Coupling
Propargylamines are versatile compounds for heterocyclic synthesis, some of which are current drugs prescribed to treat patients with Parkinson’s disease. There are different methods to synthesize propargylamines, however, modern chemistry has moved progressively to rely on new strategies that meet the principles of Green Chemistry. In this context, propargylamines are readily accessible by the cross-dehydrogenative coupling (CDC) of two C-H bonds (i.e., NCsp3-H and Csp-H bonds); surely, CDC can be considered the most atom-economic and efficient manner to form C-C bonds. The aim of this review is to provide a comprehensive survey on the synthesis of propargylamines by the CDC of amines and terminal alkynes from three fronts: (a) transition-metal homogeneous catalysis, (b) transition-metal heterogeneous catalysis and (c) photoredox catalysis. A section dealing with the asymmetric synthesis of chiral propargylamines is also included. Special attention is also devoted to the proposed reaction mechanisms.This work was generously supported by the Spanish Ministerio de Ciencia, Innovación y Universidades (MICIU; grant no. CTQ2017-88171-P), the Generalitat Valenciana (GV; grant no. AICO/2017/007) and the Instituto de Síntesis Orgánica (ISO). I.B. is also grateful to the Spanish MICIU for a Juan de la Cierva-incorporación grant (no. IJCI-2017-33706)
DNA methylation and lipid metabolism: an EWAS of 226 metabolic measures
BACKGROUND The discovery of robust and trans-ethnically replicated DNA methylation markers of metabolic phenotypes, has hinted at a potential role of epigenetic mechanisms in lipid metabolism. However, DNA methylation and the lipid compositions and lipid concentrations of lipoprotein sizes have been scarcely studied. Here, we present an epigenome-wide association study (EWAS) (N = 5414 total) of mostly lipid-related metabolic measures, including a fine profiling of lipoproteins. As lipoproteins are the main players in the different stages of lipid metabolism, examination of epigenetic markers of detailed lipoprotein features might improve the diagnosis, prognosis, and treatment of metabolic disturbances. RESULTS We conducted an EWAS of leukocyte DNA methylation and 226 metabolic measurements determined by nuclear magnetic resonance spectroscopy in the population-based KORA F4 study (N = 1662) and replicated the results in the LOLIPOP, NFBC1966, and YFS cohorts (N = 3752). Follow-up analyses in the discovery cohort included investigations into gene transcripts, metabolic-measure ratios for pathway analysis, and disease endpoints. We identified 161 associations (p~value \textless 4.7 × 10-10), covering 16 CpG sites at 11 loci and 57 metabolic measures. Identified metabolic measures were primarily medium and small lipoproteins, and fatty acids. For apolipoprotein B-containing lipoproteins, the associations mainly involved triglyceride composition and concentrations of cholesterol esters, triglycerides, free cholesterol, and phospholipids. All associations for HDL lipoproteins involved triglyceride measures only. Associated metabolic measure ratios, proxies of enzymatic activity, highlight amino acid, glucose, and lipid pathways as being potentially epigenetically implicated. Five CpG sites in four genes were associated with differential expression of transcripts in blood or adipose tissue. CpG sites in ABCG1 and PHGDH showed associations with metabolic measures, gene transcription,~and metabolic measure ratios and were additionally linked to obesity or previous myocardial infarction, extending previously reported observations. CONCLUSION Our study provides evidence of a link between DNA methylation and the lipid compositions and lipid concentrations of different lipoprotein size subclasses, thus offering in-depth insights into well-known associations of DNA methylation with total serum lipids. The results support detailed profiling of lipid metabolism to improve the molecular understanding of dyslipidemia and related disease mechanisms
Yearly evolution of organ damage markers in diabetes or metabolic syndrome: data from the LOD-DIABETES study
<p>Abstract</p> <p>Background</p> <p>Cardiovascular disease morbidity-mortality is greater in people with type 2 diabetes mellitus or metabolic syndrome. The purpose of this study was to evaluate the yearly evolution of organ damage markers in diabetes or metabolic syndrome, and to analyze the associated factors.</p> <p>Methods</p> <p>An observational prospective study was carried out in the primary care setting, involving 112 patients: 68 diabetics and 44 subjects with metabolic syndrome, subjected to 12 months of follow-up. Measurements: traditional cardiovascular risk factors (blood pressure, blood glucose, lipids, smoking, body mass index (BMI) and) and non-traditional risk factors (waist circumference, hsC Reactive Protein and fibrinogen); subclinical vascular (carotid intima-media thickness, pulse wave velocity and ankle/brachial index), cardiac (Cornell voltage-duration product), renal organ damage (creatinine, glomerular filtration and albumin/creatinine index), and antihypertensive and lipid-lowering drugs.</p> <p>Results</p> <p>At baseline, the diabetics presented a mean age of 59.9 years, versus 55.2 years in the subjects with metabolic syndrome (p = 0.03). Diastolic blood pressure, total cholesterol and HDL-cholesterol were lower among the patients with diabetes, while blood glucose and HbA1c, as well as antihypertensive and lipid-lowering drug use, were greater. At evaluation after one year, the diabetics showed a decrease in BMI (-0.39), diastolic blood pressure (-3.59), and an increase in fibrinogen (30.23 mg/dL), ankle/brachial index (0.07) and the number of patients with ankle/brachial index pathologic decreased in 6. In turn, the patients with metabolic syndrome showed an increase in HDL-cholesterol (1-91 mg/dL), fibrinogen (25.54 mg/dL), Cornell voltage-duration product (184.22 mm/ms), ankle/brachial index (0.05) and the use of antihypertensive and lipid-lowering drugs, and a reduction in serum glucose (3.74 mg/dL), HOMA, systolic (-6.76 mmHg), diastolic blood pressure (-3.29 mmHg), and pulse wave velocity (-0.72 m/s). The variable that best predicted a decrease in pulse wave velocity in subjects with metabolic syndrome was seen to be an increase in antihypertensive drug use.</p> <p>Conclusions</p> <p>The annual assessment of cardiovascular risk factors and the decrease in pulse wave velocity was more favorable in the patients with metabolic syndrome, probably influenced by the increased percentage of subjects treated with antihypertensive and lipid lowering drugs in this group.</p
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Differential effects of motor cortical excitability and plasticity in young and old individuals: a Transcranial Magnetic Stimulation (TMS) study
Aging is associated with changes in the motor system that, over time, can lead to functional impairments and contribute negatively to the ability to recover after brain damage. Unfortunately, there are still many questions surrounding the physiological mechanisms underlying these impairments. We examined cortico-spinal excitability and plasticity in a young cohort (age range: 19–31) and an elderly cohort (age range: 47–73) of healthy right-handed individuals using navigated transcranial magnetic stimulation (nTMS). Subjects were evaluated with a combination of physiological [motor evoked potentials (MEPs), motor threshold (MT), intracortical inhibition (ICI), intracortical facilitation (ICF), and silent period (SP)] and behavioral [reaction time (RT), pinch force, 9 hole peg task (HPT)] measures at baseline and following one session of low-frequency (1 Hz) navigated repetitive TMS (rTMS) to the right (non-dominant) hemisphere. In the young cohort, the inhibitory effect of 1 Hz rTMS was significantly in the right hemisphere and a significant facilitatory effect was noted in the unstimulated hemisphere. Conversely, in the elderly cohort, we report only a trend toward a facilitatory effect in the unstimulated hemisphere, suggesting reduced cortical plasticity and interhemispheric communication. To this effect, we show that significant differences in hemispheric cortico-spinal excitability were present in the elderly cohort at baseline, with significantly reduced cortico-spinal excitability in the right hemisphere as compared to the left hemisphere. A correlation analysis revealed no significant relationship between cortical thickness of the selected region of interest (ROI) and MEPs in either young or old subjects prior to and following rTMS. When combined with our preliminary results, further research into this topic could lead to the development of neurophysiological markers pertinent to the diagnosis, prognosis, and treatment of neurological diseases characterized by monohemispheric damage and lateralized motor deficits
Dietary glycemic index and retinal microvasculature in adults: a cross-sectional study
[EN] Objective: To analyze the relationship between dietary glycemic index (GI) and retinal microvasculature in adults.
Methods: This was a cross-sectional study of 300 subjects from the EVIDENT II study. Dietary GI was calculated
using a validated, semi-quantitative food frequency questionnaire. Retinal photographs were digitized, temporal
vessels were measured in an area 0.5–1 disc diameter from the optic disc and arteriolar-venular index (AVI) was
estimated with semi-automated software.
Results: AVI showed a significant difference between the tertiles of GI, after adjusting for potential confounders.
The lowest AVI values were observed among subjects in the highest tertile of GI, whereas the greatest were found
among those in the lowest tertile (estimated marginal mean of 0.738 vs. 0.768, p = 0.014).
Conclusions: In adults, high dietary GI implies lowering AVI values regardless of age, gender and other
confounding variables.
Trial registration: Clinical Trials.gov Identifier: NCT02016014. Registered 9 December 2013
Supersymmetric D-branes in the D1-D5 background
We construct supersymmetric D-brane probe solutions in the background of the
2-charge D1-D5 system on M, where M is either K3 or T^4. We focus on
`near-horizon bound states' that preserve supersymmetries of the near-horizon
AdS_3 x S^3 x M geometry and are static with respect to the global time
coordinate. We find a variety of half-BPS solutions that span an AdS_2 subspace
in AdS_3, carry worldvolume flux and can wrap an S^2 within S^3 and/or
supersymmetric cycles in M.Comment: Latex, 24 pages. v2: references added, modified Discussion, published
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Effectiveness of community-based integrated care in frail COPD patients: a randomised controlled trial
Background:
Chronic obstructive pulmonary disease (COPD) generates a high burden on health care, and hospital admissions represent a substantial proportion of the overall costs of the disease. Integrated care (IC) has shown efficacy to reduce hospitalisations in COPD patients at a pilot level. Deployment strategies for IC services require assessment of effectiveness at the health care system level. Aims:
The aim of this study was to explore the effectiveness of a community-based IC service in preventing hospitalisations and emergency department (ED) visits in stable frail COPD patients. Methods:
From April to December 2005, 155 frail community-dwelling COPD patients were randomly allocated either to IC (n=76, age 73 (8) years, forced expiratory volume during the first second, FEV1 41(19) % predicted) or usual care (n=84, age 75(9) years, FEV1 44 (20) % predicted) and followed up for 12 months. The IC intervention consisted of the following: (a) patient’s empowerment for self-management; (b) an individualised care plan; (c) access to a call centre; and (d) coordination between the levels of care. Thereafter, hospital admissions, ED visits and mortality were monitored for 6 years. Results:
IC enhanced self-management (P=0.02), reduced anxiety–depression (P=0.001) and improved health-related quality of life (P=0.02). IC reduced both ED visits (P=0.02) and mortality (P=0.03) but not hospital admission. No differences between the two groups were seen after 6 years. Conclusion:
The intervention improved clinical outcomes including survival and decreased the ED visits, but it did not reduce hospital admissions. The study facilitated the identification of two key requirements for adoption of IC services in the community: appropriate risk stratification of patients, and preparation of the community-based work force
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