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981.
Rubio-Godoy V Dutoit V Zhao Y Simon R Guillaume P Houghten R Romero P Cerottini JC Pinilla C Valmori D 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(10):5696-5707
Synthetic combinatorial peptide libraries in positional scanning format (PS-SCL) have recently emerged as a useful tool for the analysis of T cell recognition. This includes identification of potentially cross-reactive sequences of self or pathogen origin that could be relevant for the understanding of TCR repertoire selection and maintenance, as well as of the cross-reactive potential of Ag-specific immune responses. In this study, we have analyzed the recognition of sequences retrieved by using a biometric analysis of the data generated by screening a PS-SCL with a tumor-reactive CTL clone specific for an immunodominant peptide from the melanocyte differentiation and tumor-associated Ag Melan-A. We found that 39% of the retrieved peptides were recognized by the CTL clone used for PS-SCL screening. The proportion of peptides recognized was higher among those with both high predicted affinity for the HLA-A2 molecule and high predicted stimulatory score. Interestingly, up to 94% of the retrieved peptides were cross-recognized by other Melan-A-specific CTL. Cross-recognition was at least partially focused, as some peptides were cross-recognized by the majority of CTL. Importantly, stimulation of PBMC from melanoma patients with the most frequently recognized peptides elicited the expansion of heterogeneous CD8(+) T cell populations, one fraction of which cross-recognized Melan-A. Together, these results underline the high predictive value of PS-SCL for the identification of sequences cross-recognized by Ag-specific T cells. 相似文献
982.
983.
Determination of cellular strains by combined atomic force microscopy and finite element modeling 总被引:1,自引:0,他引:1
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Many organs adapt to their mechanical environment as a result of physiological change or disease. Cells are both the detectors and effectors of this process. Though many studies have been performed in vitro to investigate the mechanisms of detection and adaptation to mechanical strains, the cellular strains remain unknown and results from different stimulation techniques cannot be compared. By combining experimental determination of cell profiles and elasticities by atomic force microscopy with finite element modeling and computational fluid dynamics, we report the cellular strain distributions exerted by common whole-cell straining techniques and from micromanipulation techniques, hence enabling their comparison. Using data from our own analyses and experiments performed by others, we examine the threshold of activation for different signal transduction processes and the strain components that they may detect. We show that modulating cell elasticity, by increasing the F-actin content of the cytoskeleton, or cellular Poisson ratio are good strategies to resist fluid shear or hydrostatic pressure. We report that stray fluid flow in some substrate-stretch systems elicits significant cellular strains. In conclusion, this technique shows promise in furthering our understanding of the interplay among mechanical forces, strain detection, gene expression, and cellular adaptation in physiology and disease. 相似文献
984.
Nucci Marcio Silveira Maria Isabel Spector Nelson Silveira Fernanda Velasco Eduardo Martins Carlos Alberto Derossi Andrea Colombo Arnaldo L. Pulcheri Wolmar 《Mycopathologia》1998,141(2):65-68
The objective of this study was to characterize the epidemiology of candidemia in cancer patients in the city of Rio de Janeiro,
Brazil. An 18-month survey of fungemia in patients with cancer was undertaken in three Hospitals in Rio de Janeiro. Forty-three
episodes of candidemia were identified in 43 patients, 43 of which were episodes of candidemia; in ten cases the strains were
not available for further identification of species and were excluded from this analysis. The overall distribution of fungi
causing fungemia was: Candida albicans (5), Candida tropicalis (16), Candida parapsilosis (6), Candida guilliermondii (4),
Candida lusitaniae (1) and Candida stellatoidea (1). Antifungal prophylaxis had been administered before the episode of fungemia
in only six patients (18.2%): oral itraconazole in three patients and oral nistatin, low dose intravenous amphotericin B and
oral fluconazole in one patient each. There was no difference in the presence of risk factors, clinical characteristics or
in the outcome between albicans and non-albicans species, nor between Candida tropicalis and other non-albicans species. There
was a clear predominance of non-albicans species, regardless of the underlying disease, antifungal prophylaxis or the presence
of neutropenia.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
985.
986.
Role of Carnitine Palmitoyltransferase I in the Control of Ketogenesis in Primary Cultures of Rat Astrocytes 总被引:3,自引:2,他引:1
Cristina Blázquez Cristina Sánchez Guillermo Velasco Manuel Guzmán 《Journal of neurochemistry》1998,71(4):1597-1606
Abstract: The role of carnitine palmitoyltransferase I (CPT-I) in the control of ketogenesis was studied in primary cultures of rat astrocytes. Ketone bodies were the major product of [14 C]palmitate oxidation by cultured astrocytes, whereas CO2 made a minor contribution to the total oxidation products. Using tetradecylglycidate as a specific, cell-permeable inhibitor of CPT-I, a flux control coefficient of 0.77 ± 0.07 was calculated for CPT-I over the flux of [14 C]palmitate to ketone bodies. CPT-I from astrocytes was sensitive to malonyl-CoA (IC50 = 3.4 ± 0.8 µ M ) and cross-reacted on western blots with an antibody raised against liver CPT-I. On the other hand, astrocytes expressed significant acetyl-CoA carboxylase (ACC) activity, and consequently they contained considerable amounts of malonyl-CoA. Western blot analysis of ACC isoforms showed that ACC in astrocytes—like in neurons, liver, and white adipose tissue—mostly comprised the 265-kDa isoform, whereas the 280-kDa isoform—which was highly expressed in skeletal muscle—showed much lower abundance. Forskolin was used as a tool to study the modulation of the ketogenic pathway in astrocytes. Thus, forskolin decreased in parallel ACC activity and intracellular malonyl-CoA levels, whereas it stimulated CPT-I activity and [14 C]palmitate oxidation to both ketone bodies and CO2 . Results show that in cultured astrocytes (a) CPT-I exerts a very high degree of control over ketogenesis from palmitate, (b) the ACC/malonyl-CoA/CPT-I system is similar to that of liver, and (c) the ACC/malonyl-CoA/CPT-I system is subject to regulation by cyclic AMP. 相似文献
987.
In order to understand the molecular mechanisms which are responsible for desiccation tolerance in the resurrection plant
Craterostigma plantagineum Hochst. a thorough analysis of the CDeT11-24 gene family was performed. CDeT11-24 comprises a small gene family whose genes
are expressed in response to dehydration, salt stress and abscisic acid (ABA) treatment in leaves. The gene products are constitutively
expressed in roots and disappear only when the plants are transferred to water. It is therefore suggested that the proteins
are involved in sensing water status. The predicted proteins are very hydrophilic; they share some features with late-embryogenesis-abundant
proteins, and sequence similarities were found with two ABA- and drought-regulated Arabidopsis genes. The analysis of β-glucuronidase reporter genes driven by the CDeT11-24 promoter showed high activity in mature seeds
in both transgenic Arabidopsis and tobacco. In vegetative tissues the promoter activity in response to ABA was restricted to young Arabidosis seedlings. The responsiveness to ABA during later developmental stages was regained in the presence of the Arabidopsis gene product ABI3. Dehydration-induced promoter activity was only observed in Arabidopsis leaves at a particular developmental stage. This analysis indicates that some components in the signal transduction pathway
of the resurrection plant are not active in tobacco or Arabidopsis.
Received: 26 April 1997 / Accepted: 16 July 1997 相似文献
988.
D. Guillaume A.M. Morfaux B. Richard G. Massiot L. Le Men-Olivier J. Pusset T. Sévenet 《Phytochemistry》1984,23(10):2407-2408
Sixteen indole alkaloids have been identified in the root bark and in the leaves of Alstonia undulata from New Caledonia. They are vincamedine, tetrahydroalstonine, alstonidine, deplancheine, fluorocarpamine, pleiocarpamine, 11-methoxyakuammicine, cabucraline, desoxycabufiline, cabucraline-N(4)-oxide, 11-methoxyakuammicine N(4)-oxide, gentiacraline, plumocraline, vincorine, cathafoline and pericyclivine. Five bis indoles of unknown structure have been isolated. The root bark alkaloid mixture contains gentiacraline the first alkaloid made up of an indole and a pyridine alkaloid. 相似文献
989.
Michael E. Hochberg Guillaume Bertault Karine Poitrineau & Arne Janssen 《Entomologia Experimentalis et Applicata》2003,109(2):147-153
Although the truffle beetle, Leiodes cinnamomea, inflicts substantial damage to the ripe stage of fruiting bodies of the economically important black truffle (Tuber melanosporum), it is not attracted by ripe truffle odours. Rather, male beetles are attracted to infested truffles only in the presence of female beetles, suggesting that the former employ a pheromone to locate truffles over short distances. In contrast, female beetles show no attraction to infested or uninfested truffles, suggesting that they employ other cues, possibly linked to odours emitted by truffles prior to the ripe stage. We hypothesize that the chemical composition of truffle volatiles changes over the life of the truffle fruiting body, being attractive to insects early on and to mammals just prior to decomposition. 相似文献
990.
Ilka Haferkamp Johannes H P Hackstein Frank G J Voncken Guillaume Schmit Joachim Tjaden 《European journal of biochemistry》2002,269(13):3172-3181
The expression of mitochondrial and hydrogenosomal ADP/ATP carriers (AACs) from plants, rat and the anaerobic chytridiomycete fungus Neocallimastix spec. L2 in Escherichia coli allows a functional integration of the recombinant proteins into the bacterial cytoplasmic membrane. For AAC1 and AAC2 from rat, apparent Km values of about 40 microm for ADP, and 105 microm or 140 microm, respectively, for ATP have been determined, similar to the data reported for isolated rat mitochondria. The apparent Km for ATP decreased up to 10-fold in the presence of the protonophore m-chlorocarbonylcyanide phenylhydrazone (CCCP). The hydrogenosomal AAC isolated from the chytrid fungus Neocallimastix spec. L2 exhibited the same characteristics, but the affinities for ADP (165 microm) and ATP (2.33 mm) were significantly lower. Notably, AAC1-3 from Arabidopsis thaliana and AAC1 from Solanum tuberosum (potato) showed significantly higher external affinities for both nucleotides (10-22 microm); they were only slightly influenced by CCCP. Studies on intact plant mitochondria confirmed these observations. Back exchange experiments with preloaded E. coli cells expressing AACs indicate a preferential export of ATP for all AACs tested. This is the first report of a functional integration of proteins belonging to the mitochondrial carrier family (MCF) into a bacterial cytoplasmic membrane. The technique described here provides a relatively simple and highly reproducible method for functional studies of individual mitochondrial-type carrier proteins from organisms that do not allow the application of sophisticated genetic techniques. 相似文献