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  • Clusters of iron-rich cells in the upper beak of pigeons are macrophages not magnetosensitive neurons. 22495303

    Understanding the molecular and cellular mechanisms that mediate magnetosensation in vertebrates is a formidable scientific problem. One hypothesis is that magnetic information is transduced into neuronal impulses by using a magnetite-based magnetoreceptor. Previous studies claim to have identified a magnetic sense system in the pigeon, common to avian species, which consists of magnetite-containing trigeminal afferents located at six specific loci in the rostral subepidermis of the beak. These studies have been widely accepted in the field and heavily relied upon by both behavioural biologists and physicists. Here we show that clusters of iron-rich cells in the rostro-medial upper beak of the pigeon Columbia livia are macrophages, not magnetosensitive neurons. Our systematic characterization of the pigeon upper beak identified iron-rich cells in the stratum laxum of the subepidermis, the basal region of the respiratory epithelium and the apex of feather follicles. Using a three-dimensional blueprint of the pigeon beak created by magnetic resonance imaging and computed tomography, we mapped the location of iron-rich cells, revealing unexpected variation in their distribution and number--an observation that is inconsistent with a role in magnetic sensation. Ultrastructure analysis of these cells, which are not unique to the beak, showed that their subcellular architecture includes ferritin-like granules, siderosomes, haemosiderin and filopodia, characteristics of iron-rich macrophages. Our conclusion that these cells are macrophages and not magnetosensitive neurons is supported by immunohistological studies showing co-localization with the antigen-presenting molecule major histocompatibility complex class II. Our work necessitates a renewed search for the true magnetite-dependent magnetoreceptor in birds.
    Document Type:
    Reference
    Product Catalog Number:
    MAB1621
    Product Catalog Name:
    Anti-Neurofilament 145 kDa Antibody, CT, clone 3H11
  • Effect of weight loss and lifestyle changes on vascular inflammatory markers in obese women: a randomized trial. 12684358

    CONTEXT: Obesity is an independent risk factor for cardiovascular disease, which may be mediated by increased secretion of proinflammatory cytokines by adipose tissue. OBJECTIVE: To determine the effect of a program of changes in lifestyle designed to obtain a sustained reduction of body weight on markers of systemic vascular inflammation and insulin resistance. DESIGN AND SETTING: Randomized single-blind trial conducted from February 1999 to February 2002 at a university hospital in Italy. PATIENTS: One hundred twenty premenopausal obese women (body mass index > or =30) aged 20 to 46 years without diabetes, hypertension, or hyperlipidemia. INTERVENTIONS: The 60 women randomly assigned to the intervention group received detailed advice about how to achieve a reduction of weight of 10% or more through a low-energy Mediterranean-style diet and increased physical activity. The control group (n = 60) was given general information about healthy food choices and exercise. MAIN OUTCOME MEASURES: Lipid and glucose intake; blood pressure; homeostatic model assessment of insulin sensitivity; and circulating levels of interleukin 6 (IL-6), interleukin 18 (IL-18), C-reactive protein (CRP), and adiponectin. RESULTS: After 2 years, women in the intervention group consumed more foods rich in complex carbohydrates (9% corrected difference; P.001), monounsaturated fat (2%; P =.009), and fiber (7 g/d; P.001); had a lower ratio of omega-6 to omega-3 fatty acids (-5; P.001); and had lower energy (-310 kcal/d; P.001), saturated fat (-3.5%; P =.007), and cholesterol intake (-92 mg/d; P.001) than controls. Body mass index decreased more in the intervention group than in controls (-4.2; P.001), as did serum concentrations of IL-6 (-1.1 pg/mL; P =.009), IL-18 (-57 pg/mL; P =.02), and CRP (-1.6 mg/L; P =.008), while adiponectin levels increased significantly (2.2 microg/mL; P =.01). In multivariate analyses, changes in free fatty acids (P =.008), IL-6 (P =.02), and adiponectin (P =.007) levels were independently associated with changes in insulin sensitivity. CONCLUSION: In this study, a multidisciplinary program aimed to reduce body weight in obese women through lifestyle changes was associated with a reduction in markers of vascular inflammation and insulin resistance.
    Document Type:
    Reference
    Product Catalog Number:
    HADP-61HK
    Product Catalog Name:
    Human Adiponectin RIA
  • Regulation of AMPA receptor surface trafficking and synaptic plasticity by a cognitive enhancer and antidepressant molecule. 22733125

    The plasticity of excitatory synapses is an essential brain process involved in cognitive functions, and dysfunctions of such adaptations have been linked to psychiatric disorders such as depression. Although the intracellular cascades that are altered in models of depression and stress-related disorders have been under considerable scrutiny, the molecular interplay between antidepressants and glutamatergic signaling remains elusive. Using a combination of electrophysiological and single nanoparticle tracking approaches, we here report that the cognitive enhancer and antidepressant tianeptine (S 1574, [3-chloro-6-methyl-5,5-dioxo-6,11-dihydro-(c,f)-dibenzo-(1,2-thiazepine)-11-yl) amino]-7 heptanoic acid, sodium salt) favors synaptic plasticity in hippocampal neurons both under basal conditions and after acute stress. Strikingly, tianeptine rapidly reduces the surface diffusion of AMPA receptor (AMPAR) through a Ca(2+)/calmodulin-dependent protein kinase II (CaMKII)-dependent mechanism that enhances the binding of AMPAR auxiliary subunit stargazin with PSD-95. This prevents corticosterone-induced AMPAR surface dispersal and restores long-term potentiation of acutely stressed mice. Collectively, these data provide the first evidence that a therapeutically used drug targets the surface diffusion of AMPAR through a CaMKII-stargazin-PSD-95 pathway, to promote long-term synaptic plasticity.
    Document Type:
    Reference
    Product Catalog Number:
    MAB397
    Product Catalog Name:
    Anti-Glutamate Receptor 2 Antibody, extracellular, clone 6C4
  • Lipid rafts serve as a signaling platform for nicotinic acetylcholine receptor clustering. 16672658

    Agrin, a motoneuron-derived factor, and the muscle-specific receptor tyrosine kinase (MuSK) are essential for the acetylcholine receptor (AChR) clustering at the postjunctional membrane. However, the underlying signaling mechanisms remain poorly defined. We show that agrin stimulates a dynamic translocation of the AChR into lipid rafts-cholesterol and sphingolipid-rich microdomains in the plasma membrane. This follows MuSK partition into lipid rafts and requires its activation. Disruption of lipid rafts inhibits MuSK activation and downstream signaling and AChR clustering in response to agrin. Rapsyn, an intracellular protein necessary for AChR clustering, is located constitutively in lipid rafts, but its interaction with the AChR is inhibited when lipid rafts are perturbed. These results reveal that lipid rafts may regulate AChR clustering by facilitating the agrin/MuSK signaling and the interaction between the receptor and rapsyn, both necessary for AChR clustering and maintenance. These results provide insight into mechanisms of AChR cluster formation.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple
  • RSC exploits histone acetylation to abrogate the nucleosomal block to RNA polymerase II elongation. 17081996

    The coordinated action of histone acetyltransferases (HATs) and ATP-dependent chromatin remodeling enzymes in promoter-dependent transcription initiation represents a paradigm for how epigenetic information regulates gene expression. However, little is known about how such enzymes function during transcription elongation. Here, we investigated the role of RSC, a bromodomain-containing ATPase, in nucleosome transcription in vitro. Purified S. cerevisiae RNA polymerase II (Pol II) arrests at two primary locations on a positioned mononucleosome. RSC stimulates passage of Pol II through these sites. The function of RSC in elongation requires the energy of ATP hydrolysis. Moreover, the SAGA and NuA4 HATs strongly stimulated RSC's effect on elongation. The stimulation correlates closely with acetyl-CoA-dependent recruitment of RSC to nucleosomes. Thus, RSC can recognize acetylated nucleosomes and facilitate passage of Pol II through them. These data support the view that histone modifications regulate accessibility of the coding region to Pol II.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple