983 resultados para Escape peaks
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The performance of mice expressing PDAPP (+/+ or +/-) was studied in the Morris place navigation task. Different lines of questions were investigated using PDAPP+/- mice in which the activity of the cytokine Tumor Necrosing Factor alpha (TNFalpha) was attenuated by chronic treatment with anti-TNF or deleting TNFalpha (TNF-/-). Two different categories of behavior were analyzed in adult (6 months) and middle aged (15 months) subjects. Classically, the cognitive performance was assessed from the escape efficacy and quantitative bias toward the training position in a Morris water maze. Second, stereotyped circling was quantified, along with more qualitative behavioral impairments such as self-mutilation or increased reactivity. Our results can be summarized as follows. (1) All of the PDAPP mice expressed reduced cognitive performance in the Morris task, but only those with a clear-cut amyloid burden in the hippocampus showed behavioral abnormalities such as stereotyped circling. (2) Chronic treatment with anti-TNF prevented the development of pathological circling in the 6-month-old mice but not in the 15-month-old mice and had no significant effect on amyloid burden. (3) The absence of TNFalpha prevented the development of stereotyped circling in 6- and 15-month-old mice but increased amyloid burden after 15 months. These data indicate that PDAPP mice express cognitive impairments disregarding absence of TNF. The pathological behavioral anomalies related to the PDAPP mutation seem reduced by treatments interfering with TNFalpha.
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Gauguin's first attempts at still-life painting, around 1875, followed the Dutch tradition, influenced mainly by Manet's palette. But he did take occasional liberties in depicting flowers with more fluid colour and dynamic backgrounds. From 1879 his style shows the influence of the Impressionists: Pissarro in the landscapes and Degas in the composition of his still-lifes. He was also open to the new trends which were developing among artists in Paris and applied them in his paintings, using still-lifes as his main means for testing them. He did not escape the contemporary fascination with Japonism, and even experimented briefly with Pointillism in Still Life with Horse's Head. His stays in Britain between 1886 and 1890 correspond to an extremely rich and innovative period for him, in which still-lifes served for increasing experimentation. "Fête Gloanec" and Three Puppies reflect his preoccupations: rejection of perspective, use of areas of flat colour, and mixed styles. These pictures amount to an aesthetic manifesto; many of them are also imbued with strong symbolism, as in the Portrait of Meyer de Haan, which is a melancholic reflection on the fall of man. In Still-Life with Japanese Print, frail blue flowers seem to come out of the head of the artist-martyr, a pure product of the painter's "restless imagination". Thus Gauguin showed that art is an "abstraction" through a genre which was reputed to lend itself with difficulty to anything other than mimesis. Although he moved away from still-life after 1890, Gauguin is one of the first artists to radically renew its role and the status of still-life at the end of the 19th century, well before the Fauvists and Cubists.
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Fifty years ago, the introduction of penicillin, followed by many other antibacterial agents, represented an often underestimated medical revolution. Indeed, until that time, bacterial infections were the prime cause of mortality, especially in children and elderly patients. The discovery of numerous new substances and their development on an industrial scale confronted us with the illusion that bacterial infections were all but vanquished. However, the widespread and sometimes uncontrolled usage of these agents has led to the selection of bacteria resistant to practically all available antibiotics. Bacteria utilize three main resistance strategies: (i) decrease in drug accumulation, (ii) modification of target, and (iii) modification of the antibiotic. Bacteria can decrease drug accumulation either by becoming impermeable to antibiotics, or by actively excreting the drug accumulated in the cell. As an alternative, they can modify the structure of the antibiotic's molecular target--usually an essential metabolic enzyme of the bacteria--and thus escape the drug's toxic effect. Lastly, they can produce enzymes capable of modifying and directly inactivating the antibiotics. In addition, bacteria have evolved extremely efficient genetic transfer systems capable of exchanging and accumulating resistance genes. Some pathogens, such as methicillin-resistant Staphylococcus aureus and enterococci are now resistant to almost all available antibiotics. Vancomycin is the only non-experimental drug left to treat severe infections due to such organisms. However, vancomycin resistance has already appeared several years ago in enterococci, and was also recently described in staphylococci, in Japan, France and the United-States. Antibiotics are precious drugs which must be administered to patients who need them. On the other hand, the development of resistance must be kept under control by a better comprehension of its mechanisms and modes of transmission and by abiding by the fundamental rules of anti-infectious chemotherapy, i.e.: (i) choose the most efficient antibiotic according to clinical and local epidemiological data, (ii) target the bacteria according to the microbiological data at hand, and (iii) administer the antibiotic at an adequate dose which will leave the pathogen no chance to develop any resistance.
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Kudzu is a cover crop that has escaped cultivation in some subtropical and warm temperate regions. Kudzu has previously demonstrated broad intraspecific physiological plasticity while colonizing new environments. The objective of this paper was to investigate characteristics of kudzu leaflet anatomy that might contribute to its successful growth in climatically distinct environments, and to escape cultivation as well. Fresh and fixed leaflet strips of field-grown plants were analyzed. The lower epidermis of kudzu showed a higher frequency of stomata (147 ± 19 stomata mm-2) than the upper epidermis (26 ± 17 stomata mm-2). The average number of trichomes per square milimeter was 8 for both the upper and the lower epidermis. The average trichome length was 410 ± 200 mum for the upper epidermis and 460 ± 190 mum for the lower epidermis. Cuticle thickness was not considerably different between lower and upper epidermis. The leaflet blade consisted basically of two layers (upper and lower) of unicellular epidermis, two layers of palisade parenchyma and one layer of spongy parenchyma. One layer of paraveinal mesophyll was found between palisade and spongy parenchyma. In conclusion, leaflets of kudzu present anatomical characteristics that might contribute to the broad physiological plasticity shown by kudzu.
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Labile or mutation-sensitised proteins may spontaneously convert into aggregation-prone conformations that may be toxic and infectious. This hazardous behavior, which can be described as a form of "molecular criminality", can be actively counteracted in the cell by a network of molecular chaperone and proteases. Similar to law enforcement agents, molecular chaperones and proteases can specifically identify, apprehend, unfold and thus neutralize "criminal" protein conformers, allowing them to subsequently refold into harmless functional proteins. Irreversibly damaged polypeptides that have lost the ability to natively refold are preferentially degraded by highly controlled ATP-consuming proteases. Damaged proteins that escape proteasomal degradation can also be "incarcerated" into dense amyloids, "evicted" from the cell, or internally "exiled" to the lysosome to be hydrolysed and recycled. Thus, remarkable parallels exist between molecular and human forms of criminality, as well as in the cellular and social responses to various forms of crime. Yet, differences also exist: whereas programmed death is the preferred solution chosen by aged and aggregation-stressed cells, collective suicide is seldom chosen by lawless societies. Significantly, there is no cellular equivalent for the role of familial care and of education in general, which is so crucial to the proper shaping of functional persons in the society. Unlike in the cell, humanism introduces a bias against radical solutions such as capital punishment, favouring crime prevention, reeducation and social reinsertion of criminals.
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Modified vaccinia virus Ankara (MVA) is an attenuated double-stranded DNA poxvirus currently developed as a vaccine vector against HIV/AIDS. Profiling of the innate immune responses induced by MVA is essential for the design of vaccine vectors and for anticipating potential adverse interactions between naturally acquired and vaccine-induced immune responses. Here we report on innate immune sensing of MVA and cytokine responses in human THP-1 cells, primary human macrophages and mouse bone marrow-derived macrophages (BMDMs). The innate immune responses elicited by MVA in human macrophages were characterized by a robust chemokine production and a fairly weak pro-inflammatory cytokine response. Analyses of the cytokine production profile of macrophages isolated from knockout mice deficient in Toll-like receptors (TLRs) or in the adapter molecules MyD88 and TRIF revealed a critical role for TLR2, TLR6 and MyD88 in the production of IFNbeta-independent chemokines. MVA induced a marked up-regulation of the expression of RIG-I like receptors (RLR) and the IPS-1 adapter (also known as Cardif, MAVS or VISA). Reduced expression of RIG-I, MDA-5 and IPS-1 by shRNAs indicated that sensing of MVA by RLR and production of IFNbeta and IFNbeta-dependent chemokines was controlled by the MDA-5 and IPS-1 pathway in the macrophage. Crosstalk between TLR2-MyD88 and the NALP3 inflammasome was essential for expression and processing of IL-1beta. Transcription of the Il1b gene was markedly impaired in TLR2(-/-) and MyD88(-/-) BMDM, whereas mature and secreted IL-1beta was massively reduced in NALP3(-/-) BMDMs or in human THP-1 macrophages with reduced expression of NALP3, ASC or caspase-1 by shRNAs. Innate immune sensing of MVA and production of chemokines, IFNbeta and IL-1beta by macrophages is mediated by the TLR2-TLR6-MyD88, MDA-5-IPS-1 and NALP3 inflammasome pathways. Delineation of the host response induced by MVA is critical for improving our understanding of poxvirus antiviral escape mechanisms and for designing new MVA vaccine vectors with improved immunogenicity.
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THESIS SUMMARY : Metastasis is a multistep process involving tumour cell-autonomous features, the host tissue stroma of the primary tumour, the blood or lymphatic system as well as a receptive target organ. Most studies on factors influencing metastasis have concentrated on the characteristics of the disseminating tumour cell and on early steps of metastasis including invasion and angiogenesis. Although these steps are necessary for tumour cells to disseminate, it is the challenges encountered in the later steps of metastasis -survival while in the circulation and engraftment and outgrowth in the target organ -that account for the inefficiency of circulating tumour cells in establishing secondary lesions. Full understanding of the metastatic process therefore requires elucidation of the mechanisms that regulate these late steps, and in particular that determine what makes any given tissue permissive for metastatic tumour growth. To address this issue, we assessed the mechanisms whereby a physiological situation -pregnancy -can alter host permissiveness toward metastasis. We show that pregnant NOD/SCID mice -injected intravenously with tumour cells -develop more metastases than their non-pregnant counterparts irrespective of the tumour cell type. There was no direct effect of pregnancy-related circulating factors on tumour cell proliferation, and subcutaneous tumour growth does not vary between pregnant and nonpregnant animals. However, decreased elimination of tumour cells from the lung microvasculature was observed in pregnant mice, prompting us to assess whether pregnancy-related adaptations in innate immunity could account for this differential clearing. We found that natural killer (NK) cell fractions are decreased in blood and spleen of pregnant mice and that NK cell cytotoxicity is impaired, as reported previously. The use of NK-deficient mice or tumour cell lines resistant to NK killing abrogates the difference in metastasis load between pregnant and virgin mice. CD11 b+ Gr-1+ myeloid-derived suppressor cells (MDSC) have previously been shown to accumulate in tumour-bearing mice and to down-modulate NK activity. Accordingly, we show an increase in MDSC in pregnant mouse blood, spleen, lungs and liver. Depletion of MDSC prior to tumour cell injection decreased metastasis load in pregnant NOD/SCID mice but had no effect on virgin mice. Similarly, adoptive transfer of MDSC extracted from pregnant mice into virgin mice lead to increased metastasis take. In parallel, we investigated whether the lung and liver microenvironments are modified during pregnancy thereby providing a more "permissive soil" for the establishment of metastases. A comparative analysis of microarray data of pregnant mouse lungs and liver with "premetastatic niche" gene expression profiles of these organs shows that similar mechanisms could mediate an increase in lung and liver metastasis in pregnant mice and in mice harbouring an aggressive primary tumour. Several commonly up-regulated genes point towards the recruitment of myeloid cells, consistent with the accumulation of MDSC observed in pregnant mice. MDSC have never been evoked in the context of pregnancy before. Although the role of MDSC in pregnancy requires further investigation we suggest that MDSC accumulation constitutes an important and hitherto unrecognised common denominator of maternal immune tolerance and cancer immune escape. RESUME DE THESE : La métastatisation est un processus en plusieurs étapes qui implique des compétences particulières chez les cellules tumorales, le stroma de la tumeur primaire, les vaisseaux sanguins ou lymphatiques ainsi qu'un organe cible' réceptif. Jusqu'alors, la recherche s'est principalement intéressée aux facteurs qui influencent les étapes précoces de la métastatisation donc aux caractéristiques de la cellule métastatique, et aux processus tels que l'invasion et l'angiogenèse, tandis que peu d'études traitent des étapes tardives tel que la survie dans la circulation sanguine et l'établissement d'une lésion dans l'organe cible. En particulier, l'élucidation des facteurs qui déterminent la permissivité d'un tissu à la greffe de cellules disséminantes est indispensable à la compréhension de ce processus complexe qu'est la métastatisation. Nous proposons ici un modèle de souris récapitulant les étapes tardives de la métastatisation dans un contexte d'une permissivité accrue aux métastases chez la souris gravide, et nous évaluons les mécanismes impliqués. Les souris gestantes développent plus de métastases après l'injection intraveineuse de cellules tumorales, indépendamment du type de tumeur d'origine. Les taux élevés d'hormones et de facteurs de croissance chez la souris gravide n'inflúencent pas la prolifération des cellules tumorales et fa croissance de tumeurs sous-cutanées n'est pas non plus accélérée par la gestation. En revanche, une fois injectées, les cellules tumorales sont éliminées ` moins rapidement des vaisseaux pulmonaires chez la souris gravide que chez les contrôles. Cette observation est compatible avec un effet de la gestation sur l'immunité innée et nous avons mis en évidence une diminution des proportions de cellules NK (natural killer) dans le sang et la rate en particulier, ainsi qu'une cytotoxicité moindre envers des cellules tumorales. En utilisant des souris déficientes en cellules NK ou en injectant des cellules résistantes à l'attaqué par des cellules NK, la différence entre souris gestantes et non-gestantes disparaît. Il a été démontré chez des souris porteuses de tumeurs, que l'accumulation de cellules immunosuppressives de la lignée myélo-monocytaire (ou MDSC pour myeloid-derived suppressor tells) pouvait être responsable d'une inhibition de l'activité de cellules NK. Des nombres augmentés de ces cellules, caractérisées par les marqueurs de surface CD11b et Gr-1, ont été trouvés dans le sang, la rate, les poumons et le foie de souris gravides. Leur rôle dans la métastatisation est démontré par le fait que leur dépletion diminue le nombre de lésions secondaires chez la souris gestante, tandis que leur transfert dans des souris non-gestantes augmente le taux de métastases. L'utilisation de puces à ADN sur les foies et poumons de souris gravides a permis de mettre en évidence des différences d'expression génique proches de celles observées dans l'établissement de niches pré-métastatiques. Ceci suggère que des mécanismes similaires pourraient être responsables d'une permissivité accrue aux métastases chez la souris gravide et chez la souris porteuse d'une tumeur primaire agressive, telle que, en particulier, l'accumulation de cellules immunosuppressives dans les organes cibles. C'est la première fois que l'accumulation de MDSC est évoquée chez la souris gravide et nous proposons ici que celles-ci jouent un rôle dans la tolérance immunitaire envers le foetus et sont responsables de l'échappement de cellules tumorales injectées à la surveillance immunitaire par des cellules NK.
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PURPOSE OF REVIEW: Major advances have been made in the delineation of HIV-specific immune response and in the mechanisms of virus escape. The kinetics of the immunological and virological events occurring during primary HIV infection indicate that the establishment of the latent HIV reservoir, the major obstacle to HIV eradication likely occurs during the very early stages of primary infection, that is, the 'eclipse phase', prior to the development of the HIV-specific immune response which has limited efficacy in the control of the early events of infection. Therefore, the window of opportunity to develop effective interventions either to clear HIV during primary infection or to prevent rebound of HIV in patients successfully treated who stop antiretroviral therapy is very narrow. RECENT FINDINGS: Genetic factors most strongly associated with nonprogressive infection are human leukocyte antigen (HLA) class I alleles and particularly HLA-B5701. CD4 and CD8 T-cell responses with polyfunctional profile are associated with nonprogressive infection. Broader neutralizing antibodies are detected 3-4 years after infection, generated only in 20% of individuals but show no efficacy in the control of HIV replication. SUMMARY: In the present review, we shall discuss the different components of the HIV-specific immune response elicited by the infection, the kinetics of these responses during primary infection and the changes following transition to the chronic phase of infection, and the functional profile of 'effective' versus 'noneffective' HIV-specific immune responses.
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Natural killer (NK) cells have originally been identified based on their capacity to kill transformed cells in a seemingly non-specific fashion. Over the last 15 years, knowledge on receptor ligand systems used by NK cells to specifically detect transformed cells has been accumulating rapidly. One of these receptor ligand systems, the NKG2D pathway, has received particular attention, and now serves as a paradigm for how the immune system is able to gather information about the health status of autologous host cells. In addition to its significance on NK cells, NKG2D, as well as other NK cell receptors, play significant roles on T cells. This review aims at summarizing recent insights into the regulation of NKG2D function, the control over NKG2D ligand expression and the role of NKG2D in tumor immunity. Finally, we will discuss first attempts to exploit NKG2D function to improve immunity to tumors.
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Two goals were pursued in this research: first, to evaluate statistically some effects of sample preparation and instrument geometry on reproducibility of X-ray diffraction intensity data; and second, to develop a procedure for finding minimum peak and background counting times for a desired level of accuracy. The ratio of calcite to dolomite in limestones was determined in trials. Ultra-fine wet grinding of the limestone in porcelain impact type ball mill gave most consistent X-ray results, but caused considerable line broadening, and peaks were best measured on an area count basis. Sample spinning reduced variance about one third, and a coarse beam-medium detector slit arrangement was found to be best. An equation is developed relating coefficient of variation of a count ratio to peak and background counts. By use of the equation or graphs the minimum coefficient of variation is predicted from one fast scan, and the number and optimum arrangement of additional counting periods to reduce variation to a desired limit may be obtained. The calculated coefficient is the maximum which may be attributed to the counting statistic but does not include experimental deviations.
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The aim of this work was to design a novel strategy to detect new targets for anticancer treatments. The rationale was to build Biological Association Networks from differentially expressed genes in drug-resistant cells to identify important nodes within the Networks. These nodes may represent putative targets to attack in cancer therapy, as a way to destabilize the gene network developed by the resistant cells to escape from the drug pressure. As a model we used cells resistant to methotrexate (MTX), an inhibitor of DHFR. Selected node-genes were analyzed at the transcriptional level and from a genotypic point of view. In colon cancer cells, DHFR, the AKR1 family, PKC¿, S100A4, DKK1, and CAV1 were overexpressed while E-cadherin was lost. In breast cancer cells, the UGT1A family was overexpressed, whereas EEF1A1 was overexpressed in pancreatic cells. Interference RNAs directed against these targets sensitized cells towards MTX.
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Cytotoxic T cells that are present in tumors and capable of recognizing tumor epitopes are nevertheless generally impotent in eliciting tumor rejection. Thus, identifying the immune escape mechanisms responsible for inducing tumor-specific CD8(+) T-cell dysfunction may reveal effective strategies for immune therapy. The inhibitory receptors PD-1 and Tim-3 are known to negatively regulate CD8(+) T-cell responses directed against the well-characterized tumor antigen NY-ESO-1. Here, we report that the upregulation of the inhibitory molecule BTLA also plays a critical role in restricting NY-ESO-1-specific CD8(+) T-cell expansion and function in melanoma. BTLA-expressing PD-1(+)Tim-3(-) CD8(+) T cells represented the largest subset of NY-ESO-1-specific CD8(+) T cells in patients with melanoma. These cells were partially dysfunctional, producing less IFN-γ than BTLA(-) T cells but more IFN-γ, TNF, and interleukin-2 than the highly dysfunctional subset expressing all three receptors. Expression of BTLA did not increase with higher T-cell dysfunction or upon cognate antigen stimulation, as it does with PD-1, suggesting that BTLA upregulation occurs independently of functional exhaustion driven by high antigen load. Added with PD-1 and Tim-3 blockades, BTLA blockade enhanced the expansion, proliferation, and cytokine production of NY-ESO-1-specific CD8(+) T cells. Collectively, our findings indicate that targeting BTLA along with the PD-1 and Tim-3 pathways is critical to reverse an important mechanism of immune escape in patients with advanced melanoma.
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The success of combination antiretroviral therapy is limited by the evolutionary escape dynamics of HIV-1. We used Isotonic Conjunctive Bayesian Networks (I-CBNs), a class of probabilistic graphical models, to describe this process. We employed partial order constraints among viral resistance mutations, which give rise to a limited set of mutational pathways, and we modeled phenotypic drug resistance as monotonically increasing along any escape pathway. Using this model, the individualized genetic barrier (IGB) to each drug is derived as the probability of the virus not acquiring additional mutations that confer resistance. Drug-specific IGBs were combined to obtain the IGB to an entire regimen, which quantifies the virus' genetic potential for developing drug resistance under combination therapy. The IGB was tested as a predictor of therapeutic outcome using between 2,185 and 2,631 treatment change episodes of subtype B infected patients from the Swiss HIV Cohort Study Database, a large observational cohort. Using logistic regression, significant univariate predictors included most of the 18 drugs and single-drug IGBs, the IGB to the entire regimen, the expert rules-based genotypic susceptibility score (GSS), several individual mutations, and the peak viral load before treatment change. In the multivariate analysis, the only genotype-derived variables that remained significantly associated with virological success were GSS and, with 10-fold stronger association, IGB to regimen. When predicting suppression of viral load below 400 cps/ml, IGB outperformed GSS and also improved GSS-containing predictors significantly, but the difference was not significant for suppression below 50 cps/ml. Thus, the IGB to regimen is a novel data-derived predictor of treatment outcome that has potential to improve the interpretation of genotypic drug resistance tests.
Hypoxia-inducible miR-210 regulates the susceptibility of tumor cells to lysis by cytotoxic T cells.
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Hypoxia in the tumor microenvironment plays a central role in the evolution of immune escape mechanisms by tumor cells. In this study, we report the definition of miR-210 as a miRNA regulated by hypoxia in lung cancer and melanoma, documenting its involvement in blunting the susceptibility of tumor cells to lysis by antigen-specific cytotoxic T lymphocytes (CTL). miR-210 was induced in hypoxic zones of human tumor tissues. Its attenuation in hypoxic cells significantly restored susceptibility to autologous CTL-mediated lysis, independent of tumor cell recognition and CTL reactivity. A comprehensive approach using transcriptome analysis, argonaute protein immunoprecipitation, and luciferase reporter assay revealed that the genes PTPN1, HOXA1, and TP53I11 were miR-210 target genes regulated in hypoxic cells. In support of their primary importance in mediating the immunosuppressive effects of miR-210, coordinate silencing of PTPN1, HOXA1, and TP53I11 dramatically decreased tumor cell susceptibility to CTL-mediated lysis. Our findings show how miR-210 induction links hypoxia to immune escape from CTL-mediated lysis, by providing a mechanistic understanding of how this miRNA mediates immunosuppression in oxygen-deprived regions of tumors where cancer stem-like cells and metastatic cellular behaviors are known to evolve.
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Expression of water soluble proteins of fresh pork Longissimus thoracis from 4 pure breed pigs (Duroc, Large White, Landrace, and Piétrain) was studied to identify candidate protein markers for meat quality. Surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF-MS) was used to obtain the soluble protein profiles of Longissimus thoracis muscles. The pure breeds showed differences among the studied meat quality traits (pHu, drip loss, androstenone, marbling, intramuscular fat, texture, and moisture), but no significant differences were detected in sensory analysis. Associations between protein peaks obtained with SELDI-TOF-MS and meat quality traits, mainly water holding capacity, texture and skatole were observed. Of these peaks, a total of 10 peaks from CM10 array and 6 peaks from Q10 array were candidate soluble protein markers for pork loin quality. The developed models explained a limited proportion of the variability, however they point out interesting relationships between protein expression and meat quality