Description: Although most deoxyribonucleic acid (DNA) lesions are accurately repaired before replication, replication across unrepaired lesions is the main source of point mutations. The lesion tolerance processes, which allow damaged DNA to be replicated, entail two branches, error-prone translesion synthesis (TLS) and error-free damage avoidance (DA). While TLS pathways are reasonably well established, DA pathways are poorly understood. The fate of a replication-blocking lesion is generally explored by means of plasmid-based assays. Although such assays represent efficient tools to analyse TLS, we show here that plasmid-borne lesions are inappropriate models to study DA pathways due to extensive replication fork uncoupling. This observation prompted us to develop a method to graft, site-specifically, a single lesion in the genome of a living cell. With this novel assay, we show that in Escherichia coli DA events massively outweigh TLS events and that in contrast to plasmid, chromosome-borne lesions partially require RecA for tolerance.

Description: Background:  Even though efficacy of biologics has been extensively studied in psoriasis vulgaris, studies in erythrodermic psoriasis, the most severe form of the disease, have beenscarcelyreported. Objectives:  To address the efficacy and safety of biologics in patients with erythrodermic psoriasis. Methods:  A multicentre national retrospective study was performed using the French Psoriasis Group network. Patients showing psoriasis involving at least 90% of body surface area (BSA), and in whom severity of the disease had been evaluated before and after 3 and/or 6 months of treatment with biologics, were enrolled in the study. Results were expressed using intention to treat analysis. Results:  We included 28 patients, representing 42 flares of erythrodermic psoriasis treated with infliximab (n=24), adalimumab (7), etanercept (6), ustekinumab (3) or efalizumab (2). A 75% improvement of BSA or PASI index 12 to 14 weeks after treatment onset was reached in 48% of flares treated with infliximab, in 50% of those treated with adalimumab and in 40% of those treated with etanercept. Twelve serious adverse events consisting of bacterial infection in 7 of them were observed. Biological treatment was discontinued for safety concern in 19% of cases. A given biologic was pursued up to 48 weeks in 34% of flares. Conclusion:  Biologics show overall good short-term efficacy, but treatment switch due to lack of efficacy or side effects is frequently observed on a longer term, with one third of patients still receiving the drug after one year. The most significant safety concern consists of severe infections.

Description: Hyperpolarized [1, 13 C]pyruvate was injected rapidly into haemolysates in which hydrolysis of nicotinamide adenine dinucleotide (phosphate) (NAD(P))/NAD(P)H had been inhibited with nicotinamide. Haemolysates provide a stable glycolytic system in which membrane permeability is not a flux-controlling step, and they enable the concentration of NADH to be adjusted experimentally while keeping the rest of the sample with the same composition as that of the cytoplasm of the cell (albeit diluted twofold at the time of injection of the [1, 13 C]pyruvate). We showed that the maximum amplitude of the 13 C NMR signal from the [1, 13 C] L -lactate, produced from [1, 13 C]pyruvate, and the time at which it occurred was dependent on NADH concentration, as predicted by enzyme-kinetic analysis. The main feature of such curves was dictated by the immediacy of the supply of the co-substrate of lactate dehydrogenase (LDH, EC 1.1.1.27), and we posit that this also pertains in vivo in various tissues including neoplasms. By constructing an appropriate mathematical model and by using a Markov-chain Monte Carlo approach, we fitted experimental data to estimate LDH and NADH concentrations. Experiments carried out with only endogenous NADH present enabled the estimation of its effective concentration in human RBCs; the ability to make this estimate is a special feature of the rapid-dissolution dynamic nuclear polarization method. We found an endogenous NADH concentration in human RBCs two to four times higher than previously reported. Copyright © 2014 John Wiley & Sons, Ltd. We measured lactate dehydrogenase and NADH concentrations in human erythrocytes by using 13 C NMR rapid-dissolution dynamic nuclear polarization. A detailed enzyme kinetic model was used in the description of the experimental system, and a Markov-chain Monte Carlo procedure yielded estimates of parameter values. We report new estimates of concentrations of LDH and NADH in human erythrocytes; the former was about three times lower than previously reported while the latter was about three times higher.

Description: Background Only patients with wild-type (WT) KRAS tumors benefit from anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (Mabs) in metastatic colorectal cancer (mCRC). Pyrosequencing is now widely used for the determination of KRAS mutation burden and a conservative cut-off point of 10% has been defined. Up until now, the impact of low-frequency KRAS mutations (〈10%) on the response to anti-EGFR Mabs has yet to be evaluated. Patients and methods Tumors from patients receiving anti-EGFR Mabs based on a WT genotype for KRAS , as determined using direct sequencing, have been retrospectively analyzed by pyrosequencing. Patients were categorized as WT (no KRAS mutation) or low-frequency mutation when KRAS mutation was 〈10% ( KRAS low MT). Results A total of 168 patients treated by anti-EGFR Mabs for mCRC were analyzed. According to pyrosequencing, 138 tumors remained KRAS WT, while 30 tumors were KRAS low MT. In the KRAS low MT and KRAS WT groups, the response rates were 6.7% and 37.0%, respectively, while stabilization amounted to 23.3% versus 32.6% and progression to 70% versus 29% ( P 〈 0.01). Progression-free survival (PFS) was 2.7 ± 0.5 months for KRAS low MT and was 6.0 ± 0.3 months for KRAS WT ( P 〈 0.01). Conclusions These results appear to validate consideration of low-frequency KRAS mutation tumors as positive, and justify a large-scale prospective study.

Description: Thermal stress affects organism performance differently depending on the ambient temperature to which they are acclimatized, which varies along latitudinal gradients. This study investigated whether differences in physiological responses to temperature are consistent with regional differences in temperature regimes for the stony coral Oculina patagonica . To resolve this question we experimentally assessed how colonies originating from four different locations characterized by 〉3°C variation in mean maximum annual temperature responded to warming from 20 to 32°C. We assessed plasticity in symbiont identity, density, and photosynthetic properties, together with changes in host tissue biomass. Results show that, without changes in the type of symbiont hosted by coral colonies, O. patagonica has limited capacity to acclimatize to future warming. We found little evidence of variation in overall thermal tolerance, or in thermal optima, in response to spatial variation in ambient temperature. Given that the invader O. patagonica is a relatively new member of the Mediterranean coral fauna our results also suggest that coral populations may need to remain isolated for a long period of time for thermal adaptation to potentially take place. Our study indicates that for O. patagonica , mortality associated with thermal stress manifests primarily through tissue breakdown under moderate but prolonged warming (which does not impair symbiont photosynthesis and, therefore, does not lead to bleaching). Consequently, projected global warming is likely to causes repeat incidents of partial and whole colony mortality and might drive a gradual range contraction of Mediterranean corals. This article is protected by copyright. All rights reserved.

Description: The American Joint Committee on Cancer/Union Internationale Contre le Cancer (AJCC/UICC)-TNM staging system provides the most reliable guidelines for the routine prognostication and treatment of colorectal carcinoma. This traditional tumor staging summarizes data on tumor burden (T), the presence of cancer cells in draining and regional lymph nodes (N) and evidence for distant metastases (M). However, it is now recognized that the clinical outcome can significantly vary among patients within the same stage. The current classification provides limited prognostic information, and does not predict response to therapy. Multiple ways to classify cancer and to distinguish different subtypes of colorectal cancer have been proposed, including morphology, cell origin, molecular pathways, mutation status, and gene expression-based stratification. These parameters rely on tumor-cell characteristics. Extensive literature investigated the host-immune response against cancer and demonstrated the prognostic impact of the in situ immune cell infiltrate in tumors. A methodology named “Immunoscore” has been defined to quantify the in situ immune infiltrate. In colorectal cancer, the Immunoscore may add to the significance of the current AJCC/UICC TNM classification since it has been demonstrated to be a prognostic factor superior to the AJCC/UICC TNM-classification. An international consortium has been initiated to validate and promote the Immunoscore in routine clinical settings. The results of this international consortium may result in the implementation of the Immunoscore as a new component for the classification of cancer, designated TNM-I (TNM-Immune).

Description: Background:  Even though efficacy of biologics has been extensively studied in psoriasis vulgaris, studies in erythrodermic psoriasis, the most severe form of the disease, have beenscarcelyreported. Objectives:  To address the efficacy and safety of biologics in patients with erythrodermic psoriasis. Methods:  A multicentre national retrospective study was performed using the French Psoriasis Group network. Patients showing psoriasis involving at least 90% of body surface area (BSA), and in whom severity of the disease had been evaluated before and after 3 and/or 6 months of treatment with biologics, were enrolled in the study. Results were expressed using intention to treat analysis. Results:  We included 28 patients, representing 42 flares of erythrodermic psoriasis treated with infliximab (n=24), adalimumab (7), etanercept (6), ustekinumab (3) or efalizumab (2). A 75% improvement of BSA or PASI index 12 to 14 weeks after treatment onset was reached in 48% of flares treated with infliximab, in 50% of those treated with adalimumab and in 40% of those treated with etanercept. Twelve serious adverse events consisting of bacterial infection in 7 of them were observed. Biological treatment was discontinued for safety concern in 19% of cases. A given biologic was pursued up to 48 weeks in 34% of flares. Conclusion:  Biologics show overall good short-term efficacy, but treatment switch due to lack of efficacy or side effects is frequently observed on a longer term, with one third of patients still receiving the drug after one year. The most significant safety concern consists of severe infections.

Description: Bacteria of the genus Xenorhabdus are symbionts of soil entomopathogenic nematodes of the genus Steinernema . This symbiotic association constitutes an insecticidal complex active against a wide range of insect pests. Unlike other Xenorhabdus species, Xenorhabdus poinarii is avirulent when injected into insects in the absence of its nematode host. We sequenced the genome of the X. poinarii strain G6 and the closely related but virulent X. doucetiae strain FRM16. G6 had a smaller genome (500–700 kb smaller) than virulent Xenorhabdus strains and lacked genes encoding potential virulence factors (hemolysins, type 5 secretion systems, enzymes involved in the synthesis of secondary metabolites, and toxin–antitoxin systems). The genomes of all the X. poinarii strains analyzed here had a similar small size. We did not observe the accumulation of pseudogenes, insertion sequences or decrease in coding density usually seen as a sign of genomic erosion driven by genetic drift in host-adapted bacteria. Instead, genome reduction of X. poinarii seems to have been mediated by the excision of genomic blocks from the flexible genome, as reported for the genomes of attenuated free pathogenic bacteria and some facultative mutualistic bacteria growing exclusively within hosts. This evolutionary pathway probably reflects the adaptation of X. poinarii to specific host.

Description: In deciduous trees, shoot development in early spring is assumed to be achieved mainly at the expense of nitrogen (N) stores. Indeed, the possible compensation for poor autumn N storage by early spring N uptake has been little studied. We therefore determined the dynamics of spring N uptake in relation to spring N supply, carbon and N storage and shoot development. Young peach trees ( Prunus persica L. Batsch, cv. ‘GF305 ’ ) were raised outdoors in a hydroponic set-up during the spring and summer, with an excessive N supply. During the autumn, half of the trees were then N limited. The following spring, the N supply remained either high or low, or changed from high to low or low to high. Between 6 March and 13 May, N uptake was measured automatically on an hourly basis, while shoot growth was monitored once a week. These in situ measurements were completed by three destructive harvests to assess organ composition in N and total non-structural carbohydrates (TNC). Until the end of April, N uptake was dependent on the autumn N treatment, being higher in trees that had been N limited in the autumn. Total non-structural carbohydrate mobilization was also higher in those trees that had lost at least 17 g TNC by 24 April, while TNC levels in non-limited trees remained stable or even rose. Shoot development, estimated by the number of elongated axes and leaves per axis, was also slightly delayed by an N limitation in autumn. After 24 April, N uptake rates increased notably under all treatments and was determined by the spring N supply. In trees receiving a high N supply in the spring, the uptake rates also displayed marked short-term variations. That reduced the differences between treatments and by 13 May no differences could be evidenced between the trees in terms of organ biomass and TNC and N contents, whatever the treatment. We concluded that in the early spring, N uptake may compensate for a deficit of N storage insofar as large quantities of TNC can be mobilized for that purpose.

Description: Idiopathic CD4 + lymphocytopenia (ICL) is a rare immunodeficiency syndrome of unknown origin for which the increased risks of opportunistic infections and of malignancies have been well established but skin dysimmune diseases, including psoriasis, have been scarcely reported to now. We report herein the severe course of psoriasis in 4 patients with ICL, and show evidence for a defect in the skin recruitment of regulatory CD4 + FoxP3 + T cells. These data raise the apparent paradigm of the occurrence of a severe immunomediated disease together with a profound T-cell defect, a model which might also apply to other immune deficiencies associated with psoriasis. This article is protected by copyright. All rights reserved.