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1.
Erwan Stephan Stéphane Delanaud Cécile Bisch Jean-Pierre Libert Frédéric Telliez 《Journal of electromyography and kinesiology》2008,18(1):160-168
We present here a new, dedicated mechanical device for monitoring quick-release movements of the wrist. The ergometer was designed to easily assess musculotendinous properties during wrist flexion. Maximal voluntary contractions (MVC) and quick-release (QR) movements during wrist flexion were performed on 14 subjects. A validation of the ergometer, using a test-retest methodology, was performed to assess its reliability and sensitivity. The device has been technically and biomechanically validated in a range of situations, including inertia measurement (mean inertia was found 0.0119+/-0.0012 N m s(2) rad(-1)) and appearance of the unloading reflex. Our results indicate that the device provides highly reliable, sensitive evaluation of wrist muscle stiffness (intraclass correlation coefficient for inertia, maximal voluntary contraction and stiffness index were 0.873, 0.994 and 0.930, respectively). Its portability facilitates measurement of the influence of repetitive, occupational activity on the musculotendinous complex of the wrist flexors. 相似文献
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3.
B?rbel Maus Camille Jung Jestinah M. Mahachie John Jean-Pierre Hugot Emmanuelle Génin Kristel Van Steen 《PloS one》2013,8(10)
Complex human diseases commonly differ in their phenotypic characteristics, e.g., Crohn’s disease (CD) patients are heterogeneous with regard to disease location and disease extent. The genetic susceptibility to Crohn’s disease is widely acknowledged and has been demonstrated by identification of over 100 CD associated genetic loci. However, relating CD subphenotypes to disease susceptible loci has proven to be a difficult task. In this paper we discuss the use of cluster analysis on genetic markers to identify genetic-based subgroups while taking into account possible confounding by population stratification. We show that it is highly relevant to consider the confounding nature of population stratification in order to avoid that detected clusters are strongly related to population groups instead of disease-specific groups. Therefore, we explain the use of principal components to correct for population stratification while clustering affected individuals into genetic-based subgroups. The principal components are obtained using 30 ancestry informative markers (AIM), and the first two PCs are determined to discriminate between continental origins of the affected individuals. Genotypes on 51 CD associated single nucleotide polymorphisms (SNPs) are used to perform latent class analysis, hierarchical and Partitioning Around Medoids (PAM) cluster analysis within a sample of affected individuals with and without the use of principal components to adjust for population stratification. It is seen that without correction for population stratification clusters seem to be influenced by population stratification while with correction clusters are unrelated to continental origin of individuals. 相似文献
4.
Dominique Martinez Antoine Chaffiol Nicole Voges Yuqiao Gu Sylvia Anton Jean-Pierre Rospars Philippe Lucas 《PloS one》2013,8(4)
Insects and robots searching for odour sources in turbulent plumes face the same problem: the random nature of mixing causes fluctuations and intermittency in perception. Pheromone-tracking male moths appear to deal with discontinuous flows of information by surging upwind, upon sensing a pheromone patch, and casting crosswind, upon losing the plume. Using a combination of neurophysiological recordings, computational modelling and experiments with a cyborg, we propose a neuronal mechanism that promotes a behavioural switch between surge and casting. We show how multiphasic On/Off pheromone-sensitive neurons may guide action selection based on signalling presence or loss of the pheromone. A Hodgkin-Huxley-type neuron model with a small-conductance calcium-activated potassium (SK) channel reproduces physiological On/Off responses. Using this model as a command neuron and the antennae of tethered moths as pheromone sensors, we demonstrate the efficiency of multiphasic patterning in driving a robotic searcher toward the source. Taken together, our results suggest that multiphasic On/Off responses may mediate olfactory navigation and that SK channels may account for these responses. 相似文献
5.
Wayne W. Poon Anthony J. Carlos Brittany L. Aguilar Nicole C. Berchtold Crystal K. Kawano Vahe Zograbyan Tim Yaopruke Michael Shelanski Carl W. Cotman 《The Journal of biological chemistry》2013,288(23):16937-16948
We previously found that BDNF-dependent retrograde trafficking is impaired in AD transgenic mouse neurons. Utilizing a novel microfluidic culture chamber, we demonstrate that Aβ oligomers compromise BDNF-mediated retrograde transport by impairing endosomal vesicle velocities, resulting in impaired downstream signaling driven by BDNF/TrkB, including ERK5 activation, and CREB-dependent gene regulation. Our data suggest that a key mechanism mediating the deficit involves ubiquitin C-terminal hydrolase L1 (UCH-L1), a deubiquitinating enzyme that functions to regulate cellular ubiquitin. Aβ-induced deficits in BDNF trafficking and signaling are mimicked by LDN (an inhibitor of UCH-L1) and can be reversed by increasing cellular UCH-L1 levels, demonstrated here using a transducible TAT-UCH-L1 strategy. Finally, our data reveal that UCH-L1 mRNA levels are decreased in the hippocampi of AD brains. Taken together, our data implicate that UCH-L1 is important for regulating neurotrophin receptor sorting to signaling endosomes and supporting retrograde transport. Further, our results support the idea that in AD, Aβ may down-regulate UCH-L1 in the AD brain, which in turn impairs BDNF/TrkB-mediated retrograde signaling, compromising synaptic plasticity and neuronal survival. 相似文献
6.
Parvalbumin, a Ca2+-binding protein, was isolated from rat testis. This is the first demonstration of the protein in endocrine glands. By using a rat parvalbumin cDNA probe, parvalbumin mRNA was demonstrated in the testis, indicating that the protein is synthesized in this tissue and that testis parvalbumin is a product of the same gene as the one encoding for muscle parvalbumin. Parvalbumin was localized by immunohistochemical methods in the Leydig cells and in the acrosome region of maturing spermatids (stages 1-15). The expression of parvalbumin during testis development was followed. High parvalbumin protein and mRNA levels were found at stages of highest Leydig cell activity, i.e. at late fetal stages until birth and again around postnatal day 50. This suggests that parvalbumin may be involved in the production of testosterone in Leydig cells, a process which is highly dependent on calcium. 相似文献
7.
Chorismate aminations: partial purification of Escherichia coli PABA synthase and mechanistic comparison with anthranilate synthase 总被引:3,自引:0,他引:3
Chorismate is converted by regiospecific amination/aromatization sequences to o-aminobenzoate and p-aminobenzoate (PABA) by anthranilate synthase (AS) and PABA synthase (PABS), respectively. We report here the first partial purification of the large subunit of Escherichia coli PABA synthase, previously reported to be quantitatively inactivated in purification attempts. The subunit encoded by the pabB gene was overexpressed from a T7 promoter and purified 9-fold to 25-30% homogeneity. The pabB subunit appears unusually sensitive to inactivation by glycerol so this cosolvent is contraindicated. The Km for chorismate is 42 microM in the ammonia-dependent conversion to PABA, and we estimate a turnover number of 2.6 min-1. A variety of chorismate analogues have been prepared and examined. Of these compounds, cycloheptadienyl analogue 11 has been found to be the most potent inhibitor of Serratia marcescens anthranilate synthase (Ki = 30 microM for an RS mixture) and of the E. coli pabB subunit of PABA synthase (Ki = 226 microM). Modifications in the substituents at C-3 [enolpyruyl ether, (R)- or (S)-lactyl ether, glycolyl ether] or C-4 (O-methyl) of chorismate lead to alternate substrates. The Vmax values for (R)- and (S)-lactyl ethers are down 10-20-fold for each enzyme, and V/K analyses show the (S)-lactyl chorismate analogue to be preferred by 12/1 over (R)-lactyl for anthranilate synthase while a 3/1 preference was observed for (R)-/(S)-lactyl analogues by PABA synthase. The glycolyl ether analogue of chorismate shows 15% Vmax vs. chorismate for anthranilate synthase but is actually a faster substrate (140%) than chorismate with PABA synthase, suggesting the elimination/aromatization step from an aminocyclohexadienyl species may be rate limiting with AS but not with PABS. Indeed, studies with (R)-lactyl analogue 14 and anthranilate synthase led to accumulation of an intermediate, isolable by high-performance liquid chromatography and characterized by NMR and UV-visible spectroscopy as 6-amino-5-[(1-carboxyethyl)oxy]-1,3-cyclohexadiene-1-carboxylic acid (17). This is the anticipated intermediate predicted by our previous work with conversion of synthetic trans-6-amino-5-[(1-carboxyethenyl)oxy]-1,3-cyclohexadiene-1-carbo xylic acid (2) to anthranilate by the enzyme. Compound 17 is quantitatively converted to anthranilate on reincubation with enzyme, but at a 1.3-10-fold lower Vmax than starting lactyl substrate 14 under the conditions investigated; the basis for this kinetic variation is not yet determined. 相似文献
8.
Dinucleoside tetraphosphate variations in cultured tumor cells during their cell cycle and growth 总被引:3,自引:0,他引:3
Gilbert Moris Denise Meyer Georges Orfanoudakis Nicole Befort Jean-Pierre Ebel Pierre Remy 《Biochimie》1987,69(11-12):1217-1225
Asynchronous and synchronized cultures of A549 and HTC cells were used to detect possible, cell cycle or cell density specific variations in the intracellular pools of dinucleoside tetraphosphates (Ap4X). No important variations of the nucleotide pools were observed during cell growth. When HTC cells were released from mitotic arrest, a decrease by a factor of N3 Ap4X and ATP levels was observed when the cells entered the G1 phase. This decrease is essentially due to cell doubling. When A549 cells were released from an arrest at the G1/S boundary, the nucleotide pool size increased slightly during the G2 phase just before mitosis. This result is in agreement with both earlier data from our laboratory and the observed decrease in Ap4X pool after release from mitotic-arrested HTC cells. These results suggest that the Ap4X and ATP pools are only subjected to very small variations during the cell cycle, essentially in the G2 phase and after mitosis. 相似文献
9.
Neuromedin U-immunoreactivity in the nervous system of the small intestine of the pig and its coexistence with substance P and CGRP 总被引:2,自引:0,他引:2
Jean-Pierre Timmermans Prof. Dietrich W. Scheuermann Werner Stach Dirk Adriaensen Marie H. A. De Groodt-Lasseel Julia M. Polak 《Cell and tissue research》1989,258(2):331-337
Summary In the small intestine of the pig, neuromedin U (NMU)-immunoreactivity was mainly confined to the nerve plexus of the inner submucosal and mucosal regions. After colchicine treatment, a high number of immunoreactive nerve cell bodies was observed in the plexus submucosus internus (Meissner), whereas only a low number was found in the plexus submucosus externus (Schabadasch). The plexus myentericus as well as the aganglionic nerve meshworks in the circular and longitudinal smooth muscle layers almost completely lacked NMU-immunoreactivity. Double-labeling experiments demonstrated the occurrence of distinct NMU-containing neuron populations in the plexus submucosus internus: (1) relatively large type-II neurons revealing immunoreactivity for NMU and calcitonin gene-related peptide (CGRP) and/or substance P (SP); (2) a group of small NMU- and SP-immunoreactive neurons; (3) a relatively low number of small neurons displaying immunoreactivity for NMU but not for SP. Based on its distributional pattern, it is concluded that NMU plays an important role in the regulation and control of mucosal functions. 相似文献
10.
Fragile×expression and×inactivation 总被引:1,自引:0,他引:1
Summary The inactive fragile×chromosomes of a 47,fra(X),fra(X),Y male with a typical fragile×phenotype were successfully separated from the active homologues by means of somatic cell hybridization. It was shown by FUdR-induction and caffein-posttreatment that the separated inactive×chromosomes expressed their fragile sites and that the presence of an active mutated \sxchromosome was not a prerequisite for fragile X expression. The fragility seems to be an intrinsic property of the individual fragile site. This result is in favour of the classical concept that the fragile site at Xq27.3 has a primary pathogenetic function in this syndrome, although the fragility itself could represent a secondary phenomenon related to an unknown alteration of the DNA in this chromosome region. It is also concluded that inactivation of the fragile\sxchromosome in females is not responsible for either false negative fragile\sxfindings or the observation of fragile\sxnegative colonies isolated from fragile\sxpositive fibroblasts in heterozygotes. 相似文献