36 research outputs found
Steroid substrate-induced epimerase mechanism in the active site of the human 11β-hydroxysteroid dehydrogenase type 1
Cytochrome P4507B1 7[alpha]-hydroxylates dehydroepiandrosterone (DHEA), epiandrosterone (EpiA) and 5[alpha]-androstane-3[beta],17[beta]-diol (Adiol). 11[beta]-Hydroxysteroid dehydrogenase type 1 (11[beta]-HSD1) interconverts 7[alpha]- and 7[beta]- forms. Whether the inter-conversion proceeds through oxido-reductive steps or epimerase activity is investigated. Experiments using ^3^H-labeled 7[beta]-hydroxy-DHEA, 7[beta]-hydroxy-EpiA and 7[beta]-hydroxy-Adiol show the ^3^H-label to accumulate in 7-oxo-DHEA trap but neither in 7-oxo-EpiA nor 7-oxo-Adiol traps. Computed models of 7-oxygenated steroids dock in the active site of 11[beta]-HSD1 either in a flipped or turned form relative to cortisone and cortisol. 7-Oxo-steroid reduction in 7[alpha]- or 7[beta]-hydroxylated derivatives results from either turned or flipped forms. 11[beta]-HSD1 incubation in H~2~^18^O medium with each 7-hydroxysteroid did not incorporate ^18^O in 7-hydroxylated derivatives of EpiA and Adiol independently of the cofactor used. Thus oxido-reductive steps apply for the interconversion of 7[alpha]- and 7[beta]-hydroxy-DHEA through 7-oxo-DHEA. Epimerisation may proceed on the 7-hydroxylated derivatives of EpiA and Adiol through a mechanism involving the cofactor and Ser170
Operation Of The NuMi Beam Monitoring System
The NuMI (Neutrinos at the Main Injector) facility produces an intense neutrino beam for experiments. The NuMI Beam Monitoring system consists of four arrays of ion chambers that measure the intensity and distribution of the remnant hadron and tertiary muon beams produced in association with the neutrinos. The ion chambers operate in an environment of high particle fluxes and high radiation.Physic
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
Neurostéroïdes neuroprotecteurs (métabolisme, dosage et effets dans les maladies neurogégénératives)
La dĂ©hydroĂ©piandrostĂ©rone (DHEA) est produite dans le cerveau humain et mĂ©tabolisĂ©e en 7[alpha]- et 7[bĂȘta]-hydroxy-DHEA par le cytochrome P4507B1 (CYP7B1). Le taux de la DHEA chez l'homme diminue avec l'Ăąge, et on considĂšre donc qu'il existe une relation entre la DHEA et la neuroprotection. Cependant, le taux de la DHEA mesurĂ© dans le cerveau de sujets atteints de la maladie d'Alzheimer est plus Ă©levĂ© que chez des contrĂŽles du mĂȘme Ăąge. On sait aussi que la 7-hydroxylation est la voie principale du mĂ©tabolisme de la DHEA dans le cerveau. Nous avons donc Ă©tudiĂ© les propriĂ©tĂ©s enzymatiques du CYP7B1 humain. Pour cela, nous avons utilisĂ© le CYP7B1 humain recombinant et plusieurs 3[bĂȘta]-hydroxystĂ©roĂŻdes marquĂ©s au 14C, dont la prĂ©gnĂ©nolone, la DHEA, l'Ă©piandrostĂ©rone, le 5[alpha]-androstane-3[bĂȘta], 17[bĂȘta]-diol et l'estrone. Les mĂ©tabolites ont Ă©tĂ© identifiĂ©s par la GC/MS. Les dĂ©rivĂ©s 7[alpha]-hydroxylĂ©s sont produits en quantitĂ© majoritaire, et les dĂ©rivĂ©s 7[bĂȘta]-hydroxylĂ©s sont Ă©galement produits en quantitĂ© minoritaire. Les KM de leurs productions sont identiques, la 7[bĂȘta]-hydroxylation est une rĂ©action accessoire de la 7[alpha]-hydroxylation. La 7[alpha]-hydroxylation de la DHEA est inhibĂ©e par l'estrone et l'estradiol (inhibition mixte) et par des peptides amyloĂŻdes [bĂȘta] (inhibition non-compĂ©titive). Nous avons Ă©galement mesurĂ© et comparĂ© les taux de la DHEA et ses dĂ©rivĂ©s (la DHEAS, la 7[alpha]-hydroxy-DHEA, la 7[bĂȘta]-hydroxy-DHEA et la 16[alpha]-hydroxy-DHEA) dans le liquide cĂ©phalo-rachidien (LCR) de patients atteints de la maladie d'Alzheimer (MA) ou de la dĂ©mence vasculaire (DV) et les contrĂŽles du mĂȘme Ăąge. La DHEA est augmentĂ©e et la DHEAS est diminuĂ©e dans les deux pathologies. Les rapports de DHEA/7-hydroxy-DHEA, 7[bĂȘta]-hydroxy-DHEA/DHEA et DHEAS/DHEA montrent une diffĂ©rence significative entre les deux pathologies et les contrĂŽles. Nous avons Ă©galement notĂ© que le rapport 7[alpha]-hydroxy-DHEA/7[bĂȘta]-hydroxy-DHEA est plus Ă©levĂ© chez les patients de MA et que chez les DV. Les rĂ©sultats indiquent que la DHEA augmentĂ©e dans les cerveaux des patients n'est pas neuroprotective, et suggĂšrent que la sulfotransfĂ©rase et l'enzyme responsable pour la 7-hydroxylation de la DHEA soient moins prĂ©sentes chez les malades ou qu'elles soient formĂ©es par le polymorphisme en enzymes moins efficaces.Dehydroepiandrosterone (DHEA) is produced in the human brain and metabolised to 7[alpha]- and 7[bĂȘta]-hydroxy-DHEA by the cytochrome P4507B1 (CYP7B1). Since the DHEA levels in humans decrease with aging, it was considered that a relation between DHEA and neuroprotection was possible. However, the DHEA levels were reported much higher in the brain of patients with Alzheimer's disease (AD) than in age matched controls. It is also known that the 7-hydroxylation of DHEA is the major metabolic route in the brain. We studied the enzymatic properties of the human CYP7B1. To that end, we used recombinant human CYP7B1 and several C-labelled 2[bĂȘta]-hydroxysteroid substrates such as pregnenolone, DHEA, epiandrosterone, 5[alpha]-androstane-3[bĂȘta], 17[bĂȘta]-diol and estrone. The metabolites are identified by GC/MS. The major product was the 7[alpha]-hydroxy derivatives and the small amounts of the 7[bĂȘta]-hydroxy derivative were also characterized. Identical Km for 7[alpha]- and 7[bĂȘta]-hydroxylation indicated that 7[bĂȘta]-hydroxylation was a minor side reaction catalysed by th enzyme. The DHEA 7[alpha]-hydroxylation was inhibited by estrone and estradiol (mixed type inhibition) and by the [bĂȘta]-amyloid peptides (non-competitive inhibition). We have also measured and compared the levels of DHEA and its metabolites such as DHEAS, 7[alpha]-hydroxy-DHEA, 7[bĂȘta]-hydroxy-DHEA and 16[alpha]-hydroxy-DHEA in the cerebrospinal fluid (CSF) of patients with AD, vascular dementia (VD) and the age matched controls. DHEA was increased and DHEAS was decreased in both diseased patients. The ratios of DHEA/7-hydroxy-DHEA, 7[bĂȘta]-hydroxy-DHEA/DHEA and DHEAS/DHEA were significantly different between the patients and the controls. We also observed that the 7[alpha]-hydroxy-DHEA/7[bĂȘta]-hydroxy-DHEA ratio differed significantly between the AD and the VD. Our results indicate that the increased DHEA in neurodegenerative diseases is not neuroprotective and suggest that the sulfotransferase and the enzyme responsible for the 7-hydroxylation of DHEA are either present in lower levels or transfered by polymorphism into less efficient enzymes.PARIS-CNAM (751032301) / SudocSudocFranceF
La 7b-hydroxy-épiandrostérone dans des modÚles in vitro de cancer du sein (effets anti-estrogéniques et rÎle des récepteurs des estrogÚnes)
La 7b-hydroxy-Ă©piandrostĂ©rone, stĂ©roĂŻde endogĂšne dĂ©rivant de la DHEA, prĂ©sente des propriĂ©tĂ©s anti-inflammatoires. En effet, elle module la voie des prostaglandines (PGs) en inhibant la production de la PGE2 pro-inflammatoires et en augmentant la production de la 15-Deoxy- 12,14-PGJ2 cyto-protectrice in vivo et in vitro. Les faibles doses de 7b-hydroxy-Ă©piandrostĂ©rone (1nM, 10nM, 100nM) pour lesquelles ces effets sont observĂ©s, suggĂšrent une liaison Ă un rĂ©cepteur spĂ©cifique. L inflammation et la production des PGs jouent un rĂŽle important dans le dĂ©veloppement et la prolifĂ©ration des tumeurs mammaires estrogĂ©no-dĂ©pendantes. Le 17b-estradiol (E2), en se fixant sur les rĂ©cepteurs des estrogĂšnes (REs), induit la production de PGE2 et la prolifĂ©ration cellulaire dans ces cellules tumorales. De ce fait, notre objectif Ă©tait de tester les effets de la 7b-hydroxy-Ă©piandrostĂ©rone sur la prolifĂ©ration (comptage avec exclusion au bleu trypan), le cycle cellulaire et l apoptose (cytomĂ©trie de flux) dans les lignĂ©es cellulaires de cancer du sein MCF-7 (REa+, REb+, GPR30+) et MDA-MB-231 (REa-, REb+, GPR30+) et d identifier une(des) cible(s) potentielle(s) dans ces cellules (transactivation) et dans des cellules nĂ©gatives pour les REs nuclĂ©aires SKBr3 (GPR30+) (Ă©tudes de prolifĂ©ration). Cette Ă©tude a montrĂ© que la 7b-hydroxy-Ă©piandrostĂ©rone exerce des effets anti-estrogĂ©niques dans les cellules MCF-7 et MDA-MB-231 associĂ©s Ă une inhibition de la prolifĂ©ration et un arrĂȘt du cycle cellulaire. Les Ă©tudes de transactivation et de prolifĂ©ration avec les agonistes spĂ©cifiques des REs ont montrĂ© une interaction avec le REb. De plus, les rĂ©sultats des Ă©tudes de prolifĂ©rations sur les trois lignĂ©es cellulaires suggĂšrent que la 7b-hydroxy-Ă©piandrostĂ©rone pourrait Ă©galement interagir avec le GPR30. Ces rĂ©sultats indiquent que ce stĂ©roĂŻde androgĂšne agit comme un anti-estrogĂšne. De plus, c est la premiĂšre fois qu un stĂ©roĂŻde androgĂšne Ă faible dose montre une action anti-prolifĂ©rative dans des lignĂ©es de cancers du sein. Des Ă©tudes ultĂ©rieures restent Ă rĂ©aliser afin de mieux comprendre ces effets observĂ©s.7b-hydroxy-epiandrosterone, an endogenous androgenic derivative of DHEA, has previously been shown to exert anti-inflammatory action in vitro and in vivo via a shift from prostaglandin E2 (PGE2) to 15-deoxy- 12,14-PGJ2 production. This modulation in prostaglandin production was obtained with low concentrations of 7b-hydroxy-epiandrosterone (1 100 nM) and suggested that it might act through a specific receptor. Inflammation and prostaglandin synthesis is important in the development and survival of estrogen-dependent mammary cancers. Estrogen induced PGE2 production and cell proliferation via its binding to estrogen receptors (ERs) in these tumors. Our objective was to test the effects of 7b-hydroxy-epiandrosterone on the proliferation (by counting with trypan blue exclusion), cell cycle and cell apoptosis (by flow cytometry) of breast cancer cell lines MCF-7 (ERa+, ERb +, G-protein coupled receptor 30 : GPR30+) and MDA-MB-231 (ERa-, ERb +, GPR30+) and to identify a potential target of this steroid in these cell lineages (by transactivations) and in the nuclear ER-negative SKBr3 cells (GPR30+) (by proliferation assays). 7b-hydroxy-epiandrosterone exerted anti-estrogenic effects in MCF-7 and MDA-MB-231 cells associated with cell proliferation inhibition and cell cycle arrest. Moreover, transactivation and proliferation with ER agonists assays indicated that 7b-hydroxy-epiandrosterone interacted with ERb. Data from proliferation assays on the MCF-7, MDA-MB-231 and SKBr3 cell lines suggested that 7b-hydroxy-epiandrosterone may also act through the membrane GPR30 receptor.These results support that this androgenic steroid acts as an anti-estrogenic compound. Moreover, this is the first evidence that low doses of androgenic steroid exert antiproliferative effects in these mammary cancer cells. Further investigations are needed to improve understanding of the observed actions of endogenous 7b-hydroxy-epiandrosterone.PARIS-CNAM (751032301) / SudocSudocFranceF
Testosterone metabolism by homogenates of human prostates with benign hyperplasia: Effect of tissular concentrations of zinc, magnesium and copper
Reducing discards of demersal species using a 100Â mm square mesh cylinder: Size selectivity and catch comparison analysis
We assessed the impact of an additional 100Â mm square mesh cylinder (SMC) on the selective property of the demersal whitefish trawl in the Celtic Sea. Sea trials were conducted on board a French trawler using twin trawl rigging. We tested the effects of the position of the SMC (in front of and behind the mandatory 100Â mm square mesh panel) and of the insertion of a dispersive float. Selectivity analysis revealed the 50% retention length () to be greater than the Minimum Conservation Reference Sizes regardless of species (haddock, whiting or megrim) or rigging configuration. Results did not reveal a clear effect of the SMC position. However, the insertion of the float led to a decrease in selection ranges suggesting enhanced contact probabilities with the square meshes. With the largest values, the SMC placed in the front position (and without the float) proved to be the most selective rigging configuration and was then tested under commercial conditions. Catch comparisons revealed that the test gear retained less fish across all size classes than the commercial gear. For haddock, the test gear retained less fish below 50Â cm in length. Catch comparisons also indicated significant discards of fish above the MCRS, i.e. âhigh-gradingâ practices. Under the requirements of the landing obligation (LO), unwanted catches must be stored on-board and landed regardless of economic value. The SMC is thus a valuable tool to mitigate the impact of the LO on the demersal whitefish fishing fleets operating in the Celtic Sea