1,040 research outputs found
Experimental Research and Finite Element Modeling of 3-D Semi-Rigid Composite Joints under Proportional Loads
The behaviour of 2-D composite semi-rigid joints has been researched since the seventies, including
experimental work, numerical models, analytical models and practical methods of analysis. However,
one of the areas where research is still needed is in the three-dimensional behaviour of semi-rigid
composite joints, that is, columns with beams attached to both axes (major and minor axis).
This paper describes the details and the results of an experimental program consisting in a test of a 3D
composite semi-rigid joint. The design of major axis connection is made with a bolted flush end plate
connection while that of the minor axis is done by means of an additional plate welded to the column
flanges, rather than attach it to the column web. The specimen is subjected to proportional loads, and
further research will be done with non-proportional loads.
A finite element (FE) model is developed and validated using the experimental results. The FE model
will be used to perform a parametric study for three-dimensional semi-rigid composite joints
subjected to proportional and non-proportional loads in a future research
CELL DEATH AND VIABILITY IN MARINE PHYTOPLANKTON
CITONATAplicación de ensayos in vitro para la detección precoz de ficotoxinas en muestras de poblaciones fitoplanctónicas multiespecífica
Estudio fisiológico de Dinophysis spp. durante un ciclo de afloramiento/hundimiento en la Ría de Pontevedra
HABITFloraciones Algales Nocivas en Capas Fina
ONGOING RESEARCH ON SPECIES OF DINOPHYSIS: ALTERNATIVES WITH UNCULTURABLE DINOFLAGELLATES
Dinophysis 200
Facilitation of cholinergic transmission by combined treatment of ondansetron with flumazenil after cortical cholinergic deafferentation
We have studied the effects of concomitant blockade of 5-HT(3) and GABA(A) receptors on acetylcholine (ACh) release in the frontal cortex of rats with a selective cholinergic lesion. Lesions were performed by microinjection of the cholinergic toxin 192 IgG-saporin into the nucleus basalis magnocellularis. Single treatment with either the 5-HT(3) receptor antagonist ondansetron, 0.1 microg/kg, or the GABA(A) receptor benzodiazepine site antagonist flumazenil, 10 mg/kg, did not affect ACh release. However, the combined ondansetron + flumazenil administration significantly increased ACh release to a similar extent as a depolarising stimulus with K(+), 100 mM, at both 7 and 30 days post-lesion. Cortical perfusion with the combined ondansetron + flumazenil treatment also increased [(3)H]ACh efflux "in vitro" 30 days after lesion, suggesting that local events within the frontal cortex may participate in the interaction of ondansetron with GABAergic neurons, modulating ACh release in situations of cholinergic hypoactivity. No differences in the expression of 5-HT(3) and GABA(A) receptors in the frontal cortex were found after the cholinergic lesion. These results suggest that a combined ondansetron + flumazenil treatment would contribute to restoring a diminished cholinergic function and may provide a basis for using this treatment in the therapy of cognitive disorders associated with degeneration of the cholinergic system
Evaluation of cholinergic markers in Alzheimer's disease and in a model of cholinergic deficit
Cognitive deficits in neuropsychiatric disorders, such as Alzheimer's disease (AD), have been closely related to cholinergic deficits. We have compared different markers of cholinergic function to assess the best biomarker of cognitive deficits associated to cholinergic hypoactivity. In post-mortem frontal cortex from AD patients, acetylcholine (ACh) levels, cholinacetyltransferase (ChAT) and acetylcholinesterase (AChE) activity were all reduced compared to controls. Both ChAT and AChE activity showed a significant correlation with cognitive deficits. In the frontal cortex of rats with a selective cholinergic lesion, all cholinergic parameters measured (ACh levels, ChAT and AChE activities, "in vitro" and "in vivo" basal ACh release) were significantly reduced. AChE activity was associated to ChAT activity, and even more, to "in vivo" and "in vitro" basal ACh release. Quantification of AChE activity is performed by an easy and cheap method and therefore, these results suggest that determination of AChE activity may be used as an effective first step method to evaluate cholinergic deficits
Increased circulating and visceral adipose tissue expression levels of YKL-40 in obesity-associated type 2 diabetes are related to inflammation: impact of conventional weight loss and gastric bypass
Context: Plasma YKL-40 is elevated in patients with type 2 diabetes. The potential role of visceral
adipose tissue (VAT) as a significant source of YKL-40 is unknown.
Objective: In the study circulating and expression levels of YKL-40 were examined in VAT analyzing
the contribution of adipocytes and stromovascular fraction cells (SVFCs).Wealso explored YKL-40’s
implication in insulin resistance and inflammation and the effect of weight loss on plasma YKL-40
concentrations.
PatientsandMethods: Samples obtained from 53 subjects were used in the study.Geneandprotein
expression levels of YKL-40 were analyzed in VAT as well as in both adipocytes and SVFCs. In
addition, circulating YKL-40 concentrations were measured before and after weight loss achieved
either by Roux-en-Y gastric bypass (n 26) or after a conventional dietetic program (n 20).
Results: Circulating concentrations and VAT expression of YKL-40 were increased in obese patients
with type 2 diabetes (P 0.01) as well as associated with variables of insulin resistance and inflammation.
No differences in YKL-40 expression levels between adipocytes and SVFCs were detected.
Monocyte chemoattractant protein-1 and homeostasis model assessment emerged (P
0.01) as independent factors predicting circulating YKL-40. Elevated levels of YKL-40 in obese
patients decreased after weight loss following a conventional hypocaloric diet (P 0.05) but not
via a surgery-induced negative energy balance mediated by the Roux-en-Y gastric bypass.
Conclusions: The association of increased YKL-40 mRNA and protein levels in VAT with its circulating
concentrations indicates an important contribution of VAT in YKL-40 regulation. Furthermore,
our data suggest a relevant role of glucose metabolism and inflammation on YKL-40
regulation
Issues related to the MEDITS reference list of species
The MEDITS survey programme started in 1994 and adopted the basic protocols by the four first partners, just before the first survey. These protocols included the design of the survey, the sampling gear, the information collected, and the management of the data as far as the production of common standardized analyses of the data (Bertrand et al., 2002). The last updating of protocols has been done in 2007 (MEDITS, 2007). According to it, for each species the total weight and number of individuals is recorded. For a reference list of 38 species of fish, crustaceans and cephalopods, the length frequency by sex must be reported, as well as the maturity stage of the gonads. However, two different things should be taken into account. On one hand, for most works performed using MEDITS data (including assessments), the length frequency distributions are used, without taking into account the sex. On the other hand, the period of the surveys is not always coincident with the spawning season for all the species in the MEDITS reference list. This document attempts to be a practical exercise in relation to these topics, using both surveys and commercial data, and gives some proposals to the reference list of specie
Involvement of an altered 5-HT -{6} receptor function in behavioral symptoms of Alzheimer's disease
We studied the hypothesis that disturbances in 5-HT_{6} receptor function in the temporal cortex may contribute to clinical symptoms of Alzheimer's disease (AD). 5-HT_{6} density and 5-HT levels were significantly decreased in a cohort of AD patients prospectively assessed for cognitive/behavioral symptoms. cAMP formation after stimulation with the selective 5-HT_{6} receptor agonist E-6801 was significantly lower (p<0.01) in AD (170.02 +/- 27.53 pmol/mg prot.) compared to controls (823.33 +/-196.67). In addition, the ratio cAMP formation after stimulation with E-6801/5-HT_{6} receptor density was significantly lower (p< 0.01) in AD (6.67 +/- 0.83) compared to controls (16.67 +/- 3.33). Splitting these results by sex, 5-HT_{6} receptor activation was significantly lower (p< 0.01) in AD females compared to males (121.67 +/- 30.02 vs. 231.67 +/- 34.17 pmol/mg prot). 5-HT_{6} density and 5-HT levels were significantly correlated (p < or = 0.01) in both controls and AD patients, although in AD, this correlation was lost in females. Psychosis factor was the best predictor of reduced 5-HT levels or adenylate cyclase activity after E-6801 stimulation, the former result being due to females. It may be suggested that psychotic symptoms may be related to a dysregulation of 5-HT_{6} activation by 5-HT in the temporal cortex. These results are discussed in terms of purported influence of sex and therapeutical approaches to psychosis in AD
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