Marqueurs biologiques des statuts vitaminiques B12 et D: aspects analytiques d'importance clinique [Biological markers for the status of vitamins B12 and D: the importance of some analytical aspects in relation to clinical interpretation of results].

Biological markers for the status of vitamins B12 and D: the importance of some analytical aspects in relation to clinical interpretation of results When vitamin B12 deficiency is expressed clinically, the diagnostic performance of total cobalamin is identical to that of holotranscobalamin II. In subclinical B12 deficiency, the two aforementioned markers perform less well. Additional analysis of a second, functional marker (methylmalonate or homocysteine) is recommended. Different analytical approaches for 25-hydroxyvitamin D quantification, the marker of vitamin D deficiency, are not yet standardized. Measurement biases of up to +/- 20% compared with the original method used to establish threshold values are still observed.

Association of pharmacogenetic markers with premature discontinuation of first-line anti-HIV therapy: an observational cohort study.

BACKGROUND: Poor tolerance and adverse drug reactions are main reasons for discontinuation of antiretroviral therapy (ART). Identifying predictors of ART discontinuation is a priority in HIV care. METHODS: A genetic association study in an observational cohort to evaluate the association of pharmacogenetic markers with time to treatment discontinuation during the first year of ART. Analysis included 577 treatment-naive individuals initiating tenofovir (n = 500) or abacavir (n = 77), with efavirenz (n = 272), lopinavir/ritonavir (n = 184), or atazanavir/ritonavir (n = 121). Genotyping included 23 genetic markers in 15 genes associated with toxicity or pharmacokinetics of the study medication. Rates of ART discontinuation between groups with and without genetic risk markers were assessed by survival analysis using Cox regression models. RESULTS: During the first year of ART, 190 individuals (33%) stopped 1 or more drugs. For efavirenz and atazanavir, individuals with genetic risk markers experienced higher discontinuation rates than individuals without (71.15% vs 28.10%, and 62.5% vs 14.6%, respectively). The efavirenz discontinuation hazard ratio (HR) was 3.14 (95% confidence interval (CI): 1.35-7.33, P = .008). The atazanavir discontinuation HR was 9.13 (95% CI: 3.38-24.69, P < .0001). CONCLUSIONS: Several pharmacogenetic markers identify individuals at risk for early treatment discontinuation. These markers should be considered for validation in the clinical setting.

Protein-binding microarrays: probing disease markers at the interface of proteomics and genomics.

DNA-binding proteins mediate a variety of crucial molecular functions, such as transcriptional regulation and chromosome maintenance, replication and repair, which in turn control cell division and differentiation. The roles of these proteins in disease are currently being investigated using microarray-based approaches. However, these assays can be difficult to adapt to routine diagnosis of complex diseases such as cancer. Here, we review promising alternative approaches involving protein-binding microarrays (PBMs) that probe the interaction of proteins from crude cell or tissue extracts with large collections of synthetic or natural DNA sequences. Recent studies have demonstrated the use of these novel PBM approaches to provide rapid and unbiased characterization of DNA-binding proteins as molecular markers of disease, for example cancer progression or infectious diseases.

Chromosome localization of microsatellite markers in the shrews of the Sorex araneus group.

The extremely high rate of karyotypic evolution that characterizes the shrews of the Sorex araneus group makes this group an exceptionally interesting model for population genetics and evolutionary studies. Here, we attempted to map 46 microsatellite markers at the chromosome arm level using flow-sorted chromosomes from three karyotypically different taxa of the Sorex araneus group (S. granarius and the chromosome races Cordon and Novosibirsk of S. araneus). The most likely localizations were provided for 35 markers, among which 25 were each unambiguously mapped to a single locus on the corresponding chromosomes in the three taxa, covering the three sexual chromosomes (XY1Y2) and nine of the 18 autosomal arms of the S. araneus group. The results provide further evidence for a high degree of conservation in genome organization in the S. araneus group despite the presence of numerous Robertsonian rearrangements. These markers can therefore be used to compare the genetic structure among taxa of the S. araneus group at the chromosome level and to study the role of chromosomal rearrangements in the genetic diversification and speciation process of this group.

Cerebral and extracerebral cholesterol metabolism and CSF markers of Alzheimer's disease.

The disturbances of the cholesterol synthesis and metabolism described in Alzheimer's disease (AD) may be both a consequence of the neurodegenerative process and a contributor to the pathogenesis. These putative relationships and their underlying mechanisms are not well understood. The aim of this study was to evaluate the relationship between the cerebral and extracerebral cholesterol synthesis and metabolism, and the AD pathology as reflected by CSF markers in humans. We evaluated the relationships between the plasma and the cerebrospinal fluid (CSF) concentrations of cholesterol, the cholesterol precursors lanosterol, lathosterol and desmosterol, and the cholesterol elimination products 24S-hydroxycholesterol and 27-hydroxycholesterol, and the CSF markers for AD pathology Aβ1-42 and p-tau181 in 86 subjects with normal cognition and in 107 AD patients. CSF desmosterol, cholesterol and 24S-hydroxycholesterol in the AD group, and CSF 24S-hydroxycholesterol in the control group correlated with the p-tau181 levels. Neither CSF nor plasma concentrations of the included compounds correlated with the CSF Aβ1-42 levels. In multivariate regression tests including age, gender, albumin ratio, number of the APOEε4 alleles, and diagnosis, p-tau181 levels independently predicted the CSF desmosterol, cholesterol and 24S-hydroxycholesterol concentrations. The associations remained significant for CSF cholesterol and 24S-hydroxycholesterol when analyses were separately performed in the AD group. The results suggest that alterations of CNS cholesterol de novo genesis and metabolism are related to neurodegeneration and in particular to the cerebral accumulation of phosphorylated tau.

Prospective study on procalcitonin and other systemic infection markers in patients with leukocytosis.

OBJECTIVE: To better assess the diagnosis of an infection in patients presenting at an emergency department with peripheral blood leukocytosis (>10 x 10(9) cells/l) on laboratory testing. METHODS: We prospectively evaluated serum procalcitonin concentration (PCT), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). Patients were divided into two groups according to their final diagnosis: patients with infection and those without infection. PCT, CRP, and ESR were compared between these groups. Sensitivity, specificity, positive predictive values, negative predictive values, receiver operating characteristic curves, and areas under the curves were calculated for each biological measurement. RESULTS: Out of 173 patients, 99 (57%) had a final diagnosis of systemic infection. If a cutoff point of 0.5 ng/ml is considered, procalcitonin concentration had a sensitivity of 0.57, a specificity of 0.85, a negative predictive value of 0.59, and a positive predictive value of 0.84 for the diagnosis of a systemic infection. Adding CRP or ESR to PCT gave no more information (p=0.84). CONCLUSIONS: Only about half of the patients attending the emergency department with leukocytosis were suffering from an infection. Determination of the procalcitonin level may be useful for these patients, particularly in the case of a value higher than 0.5 ng/ml.

Evolutionary dynamics of molecular markers during local adaptation: a case study in Drosophila subobscura

Background: Natural selection and genetic drift are major forces responsible for temporal genetic changes in populations. Furthermore, these evolutionary forces may interact with each other. Here we study the impact of an ongoing adaptive process at the molecular genetic level by analyzing the temporal genetic changes throughout 40 generations of adaptation to a common laboratory environment. Specifically, genetic variability, population differentiation and demographic structure were compared in two replicated groups of Drosophila subobscura populations recently sampled from different wild sources. Results: We found evidence for a decline in genetic variability through time, along with an increase in genetic differentiation between all populations studied. The observed decline in genetic variability was higher during the first 14 generations of laboratory adaptation. The two groups of replicated populations showed overall similarity in variability patterns. Our results also revealed changing demographic structure of the populations during laboratory evolution, with lower effective population sizes in the early phase of the adaptive process. One of the ten microsatellites analyzed showed a clearly distinct temporal pattern of allele frequency change, suggesting the occurrence of positive selection affecting the region around that particular locus. Conclusion: Genetic drift was responsible for most of the divergence and loss of variability between and within replicates, with most changes occurring during the first generations of laboratory adaptation. We also found evidence suggesting a selective sweep, despite the low number of molecular markers analyzed. Overall, there was a similarity of evolutionary dynamics at the molecular level in our laboratory populations, despite distinct genetic backgrounds and some differences in phenotypic evolution.

Nonspecific PCR amplification by high-fidelity polymerases: implications for next-generation sequencing of AFLP markers.

High-fidelity 'proofreading' polymerases are often used in library construction for next-generation sequencing projects, in an effort to minimize errors in the resulting sequence data. The increased template fidelity of these polymerases can come at the cost of reduced template specificity, and library preparation methods based on the AFLP technique may be particularly susceptible. Here, we compare AFLP profiles generated with standard Taq and two versions of a high-fidelity polymerase. We find that Taq produces fewer and brighter peaks than high-fidelity polymerase, suggesting that Taq performs better at selectively amplifying templates that exactly match the primer sequences. Because the higher accuracy of proofreading polymerases remains important for sequencing applications, we suggest that it may be more effective to use alternative library preparation methods.

Some historic markers in Iowa,1943.

This book is part of the Iowa Monograph Series, number 8, edited by Ruth A. Gallager. It was compiled by Susie Webb Wright and includes information on markers and monuments in Iowa which tell of people, places, incidents, or events connected with Iowa history.

Effect of n-3 fatty acids on cerebral markers and the inflammatory response in sepsis

Introduction ICM+ software encapsulates our 20 years' experience in brain monitoring. It collects data from a variety of bedside monitors and produces time trends of parameters defi ned using confi gurable mathematical formulae. To date it is being used in nearly 40 clinical research centres worldwide. We present its application for continuous monitoring of cerebral autoregulation using near-infrared spectroscopy (NIRS). Methods Data from multiple bedside monitors are processed by ICM+ in real time using a large selection of signal processing methods. These include various time and frequency domain analysis functions as well as fully customisable digital fi lters. The fi nal results are displayed in a variety of ways including simple time trends, as well as time window based histograms, cross histograms, correlations, and so forth. All this allows complex information from bedside monitors to be summarized in a concise fashion and presented to medical and nursing staff in a simple way that alerts them to the development of various pathological processes. Results One hundred and fi fty patients monitored continuously with NIRS, arterial blood pressure (ABP) and intracranial pressure (ICP), where available, were included in this study. There were 40 severely headinjured adult patients, 27 SAH patients (NCCU, Cambridge); 60 patients undergoing cardiopulmonary bypass (John Hopkins Hospital, Baltimore) and 23 patients with sepsis (University Hospital, Basel). In addition, MCA fl ow velocity (FV) was monitored intermittently using transcranial Doppler. FV-derived and ICP-derived pressure reactivity indices (PRx, Mx), as well as NIRS-derived reactivity indices (Cox, Tox, Thx) were calculated and showed signifi cant correlation with each other in all cohorts. Errorbar charts showing reactivity index PRx versus CPP (optimal CPP chart) as well as similar curves for NIRS indices versus CPP and ABP were also demonstrated. Conclusions ICM+ software is proving to be a very useful tool for enhancing the battery of available means for monitoring cerebral vasoreactivity and potentially facilitating autoregulation guided therapy. Complexity of data analysis is also hidden inside loadable profi les, thus allowing investigators to take full advantage of validated protocols including advanced processing formulas.

Monitoring of biological markers indicative of doping: the athlete biological passport

The athlete biological passport (ABP) was recently implemented in anti-doping work and is based on the individual and longitudinal monitoring of haematological or urine markers. These may be influenced by illicit procedures performed by some athletes with the intent to improve exercise performance. Hence the ABP is a valuable tool in the fight against doping. Actually, the passport has been defined as an individual and longitudinal observation of markers. These markers need to belong to the biological cascade influenced by the application of forbidden hormones or more generally, affected by biological manipulations which can improve the performance of the athlete. So far, the haematological and steroid profile modules of the ABP have been implemented in major sport organisations, and a further module is under development. The individual and longitudinal monitoring of some blood and urine markers are of interest, because the intraindividual variability is lower than the corresponding interindividual variability. Among the key prerequisites for the implementation of the ABP is its prospect to resist to the legal and scientific challenges. The ABP should be implemented in the most transparent way and with the necessary independence between planning, interpretation and result management of the passport. To ensure this, the Athlete Passport Management Unit (APMU) was developed and the WADA implemented different technical documents associated to the passport. This was carried out to ensure the correct implementation of a profile which can also stand the challenge of any scientific or legal criticism. This goal can be reached only by following strictly important steps in the chain of production of the results and in the management of the interpretation of the passport. Various technical documents have been then associated to the guidelines which correspond to the requirements for passport operation. The ABP has been completed very recently by the steroid profile module. As for the haematological module, individual and longitudinal monitoring have been applied and the interpretation cascade is also managed by a specific APMU in a similar way as applied in the haematological module. Thus, after exclusion of any possible pathology, specific variation from the individual norms will be then considered as a potential misuse of hormones or other modulators to enhance performance.

Sex-linked genetic markers in the shrews of the Sorex araneus group : from free gene flow to speciation

SUMMARY: The shrews of the Sorex araneus group are morphologically .very similar, but have undergone a spectacular chromosomal evolution. Altogether, the shrews of this group present a complete array of every possible level of chromosomal and genetic differentiation. In South-Western Europe, four species are recognised: S. antiriorii, S. araneus, S. coronatus and S. granarius, which differ essentially by the amount and the composition of Robertsonian metacentric chromosomés. Additionally, several chromosome races of S. araneus are also present in the same region (i.e. Bretolet, Carlit, Cordon, Jura and Vaud). The objective of this thesis was to examine the genetic relationships between populations, races and /or species of the Sorex araneus group with a special emphasis onsex-specific markers (mtDNA and Y chromosome). We first investigate the evolutionary history of the shrews of the Sorex araneus group distributed in the South-Western Europe. The results of. these analyses confirmed the difficulty to draw a single dichotomic tree within this group. Incongruent mtDNA and Y chromosome phylogenies suggest further that genetic and chromosomal evolution are in this group partially independent processes and that the evolutionary history of the south-western European populations of the S. araneus group can only be understood if we consider secondary contacts between taxa, after their divergence (with genetic exchanges by means of hybridization and / or introgression). Using one male-inherited, one female inherited and eight biparentally inherited markers, we investigate the population genetic structure of the Valais shrew (Sorex antinorii). Overall there results suggest that two already well-differentiated genetic lineages colonized the Swiss Alps after the last glacial period and came into contact in the Rhône Valley. After the Valais shrew (Sorex antinorii) reached the Swiss Alps, it came into contact with the common shrew (Sorex araneus). When two species come into contact and hybridize, endogenous counter-selection of hybrids is usually first expressed as a reduced fertility or viability in hybrids of the heterogametic sex, a mechanism know as Haldane's rule (Haldane 1922). We first evaluated the extent of introgression for Y chromosome, mtDNA and autosomal markers in a hybrid zone between S. antinoriii and S. araneus. The overall level of genetic and karyotypic differentiation between the two species must be strong .enough to allow the detection asymmetric introgression. Secondly, we compared the levels of gene flow between chromosome common to both species and chromosome differently rearranged in each of them. We detected a significantly stronger genetic structure in rearranged chromosomes. Over a 10-year period, we even observed a decrease of genetic structure for common chromosomes. These results strongly support the role of chromosomal rearrangements in the reproductive barrier between S. araneus and S. anfinorii. Overall, this thesis underlines the need to use different inherited (paternally, maternally and / or biparentally) and chromosomally located (on common vs. on rearranged chromosomes) markers to obtain more accurate pictures of genetic relationships between populations or species. RÉSUMÉ: Les musaraignes du groupe Sorex araneus sont morphologiquement très proches, mais ont connu une spectaculaire évolution chromosomique. Prises dans leur ensemble, les musaraignes de ce groupe présentent tous les nivaux possibles de différenciation génétique et chromosomique. Dans le sud-ouest de l'Europe, quatre espèces appartenant à ce groupe sont présentes : S. antinorii, S. araneus, S. coronatus et S. granarius. Celles-ci diffèrent essentiellement par leur caryotype dont la variabilité est principalement due à des fusions Robertsoniennes. De plus, plusieurs races chromosomiques appartenant à S. araneus sont aussi présentes dans la même région (i.e. les races Bretolet, Carlit, Cordon, Jura et Vaud). L'objectif de cette thèse était d'examiner les relations génétiques entre populations, races et/ou espèces du groupe S. araneus, en utilisant particulièrement des marqueurs liés aux sexes (ADN mitochondrial et Chromosome Y). Nous avons dans un premier temps retracé l'histoire évolutive des musaraignes de ce groupe dans le sud-ouest de l'Europe. Les résultats dé ces analyses confirment qu'il est difficile de tracer un simple arbre dichotomique au sein de ce groupe. Les arbres phylogénétiques obtenus sur l'ADN mitochondrial et le chromosome Y sont incongruents et suggèrent de plus que l'évolution génétique et chromosomique sont des processus indépendants. L'histoire évolutive -des populations de ce groupe ne peut. être comprise qu'en considérant des contacts secondaires entre taxa postérieure à leur divergence et induisant des échanges génétiques par hybridation et/ou introgression. Par la suite, nous avons examiné la structure génétique des populations de la musaraigne du Valais, S. antinorii, en utilisant un marqueur transmis par les mâles, un marqueur transmis par les femelles et huit marqueurs transmis par les 2 sexes. Nos résultats suggèrent que deux lignées génétiquement bien différenciées aient colonisé les Alpes Suisses, après les dernières glaciations et entrent en contact dans là Vallée du Rhône. Après avoir franchi les Alpes Suisses, la musaraigne du Valais est entrée en contact avec là musaraigne commune (S. araneus). Lorsque deux espèces entrent en contact et s'hybrident, la sélection contre les hybrides implique habituellement une baisse de fertilité ou de viabilité des hybrides du sexe hétérogamétique (i.e. les mâles XY chez les mammifères). Ce mécanisme est connu sous le nom de règle de Haldane (Haldane 1922) et implique une plus forte structuration génétique de marqueurs males - spécifiques que des marqueurs femelles spécifiques. Nous avons donc évalué le degré d'introgression des marqueurs situés sur le chromosome Y, sur l'ADN mitochondrial et sur des autosomes dans une zone hybride entre S. araneus et S. antinorii. Le niveau de différenciation chromosomique et génétique entre les 2 espèces doit être suffisamment fort pour ne pas permettre la détection d'une introgression asymétrique entre les sexes. Dans un second temps, nous avons comparé les niveaux de flux de gênes mesurés à l'échelle du chromosome, pour des chromosomes communs aux deux espèces et pour des chromosomes différemment arrangées dans chacune des deux espèces. Nous avons détecté une structure génétique significativement plus forte sur les chromosomes réarrangés et comme la zone hybride a été étudiée à dix années d'intervalle, nous observons même une diminution de la structure génétique pour les chromosomes communs au cours du temps.. Ces résultats soutiennent fortement l'hypothèse d'un rôle des réarrangements chromosomiques dans l'établissement d'une barrière reproductive entre S. araneus et S. antinorii. Ainsi cette thèse souligne l'utilité d'utiliser des marqueurs génétiques avec différents modes de transmission. (par les mâles, par les femelles et/ou par les 2 sexes) ou localisés au niveau du chromosome (chromosomes communs vs chromosomes réarrangés) afin d'obtenir une image plus juste ou du moins plus complète des relations génétiques entre populations ou espèces.

Distinct requirements for activation-induced cell surface expression of preformed Fas/CD95 ligand and cytolytic granule markers in T cells.

Fas (CD95/Apo-1) ligand is a potent inducer of apoptosis and one of the major killing effector mechanisms of cytotoxic T cells. Thus, Fas ligand activity has to be tightly regulated, involving various transcriptional and post-transcriptional processes. For example, preformed Fas ligand is stored in secretory lysosomes of activated T cells, and rapidly released by degranulation upon reactivation. In this study, we analyzed the minimal requirements for activation-induced degranulation of Fas ligand. T cell receptor activation can be mimicked by calcium ionophore and phorbol ester. Unexpectedly, we found that stimulation with phorbol ester alone is sufficient to trigger Fas ligand release, whereas calcium ionophore is neither sufficient nor necessary. The relevance of this process was confirmed in primary CD4(+) and CD8(+) T cells and NK cells. Although the activation of protein kinase(s) was absolutely required for Fas ligand degranulation, protein kinase C or A were not involved. Previous reports have shown that preformed Fas ligand co-localizes with other markers of cytolytic granules. We found, however, that the activation-induced degranulation of Fas ligand has distinct requirements and involves different mechanisms than those of the granule markers CD63 and CD107a/Lamp-1. We conclude that activation-induced degranulation of Fas ligand in cytotoxic lymphocytes is differently regulated than other classical cytotoxic granule proteins.