Quantitative assay for the detection of the V617F variant in the Janus kinase 2 (JAK2) gene using the Luminex xMAP technology

<p>Abstract</p> <p>Background</p> <p>The availability of clinically valid biomarkers contribute to improve the diagnosis and clinical management of diseases. A valine-to-phenylalanine substitution at position 617 (V617F) in the Janus kinase 2 (JAK2) gene has been recently associated with key signaling abnormalities in the transduction of haemopoietic growth-factor receptors and is now considered as a useful clinical marker of myeloproliferative neoplasms. Several methods have recently been reported to detect the JAK2 V617F point mutation and show variable sensitivity.</p> <p>Methods</p> <p>Using the Luminex xMAP technology, we developed a quantitative assay to detect the JAK2V617F variant. The method was based on polymerase chain reaction (PCR) followed by hybridization to specific probes coupled with internally dyed microspheres. The assay comprises 3 steps: genomic DNA extraction, end point PCR reaction, direct hybridization of PCR fragments and quantification. It has been tested with different sources of nucleic acid.</p> <p>Results</p> <p>Applied to whole blood samples, this quantitative assay showed a limit of detection of 2%. A highly sensitive allele-specific primer extension reaction performed in parallel allowed to validate the results and to identify the specimens with values below 2%.</p> <p>Conclusion</p> <p>Direct hybridization assay using the Luminex xMAP technology allows sensitive quantification of JAK2V617F from blood spots. It is simple and can be easily performed in a clinical setting.</p

SDF1-Induced Antagonism of Axonal Repulsion Requires Multiple G-Protein Coupled Signaling Components That Work in Parallel

SDF1 reduces the responsiveness of axonal growth cones to repellent guidance cues in a pertussis-toxin-sensitive, cAMP-dependent manner. Here, we show that SDF1's antirepellent effect can be blocked in embryonic chick dorsal root ganglia (DRGs) by expression of peptides or proteins inhibiting either Gαi, Gαq, or Gβγ. SDF1 antirepellent activity is also blocked by pharmacological inhibition of PLC, a common effector protein for Gαq. We also show that SDF1 antirepellent activity can be mimicked by overexpression of constitutively active Gαi, Gαq, or Gαs. These results suggest a model in which multiple G protein components cooperate to produce the cAMP levels required for SDF1 antirepellent activity

Detection of Wolbachia in the Tick Ixodes ricinus is Due to the Presence of the Hymenoptera Endoparasitoid Ixodiphagus hookeri

The identification of micro-organisms carried by ticks is an important issue for human and animal health. In addition to their role as pathogen vectors, ticks are also the hosts for symbiotic bacteria whose impact on tick biology is poorly known. Among these, the bacterium Wolbachia pipientis has already been reported associated with Ixodes ricinus and other tick species. However, the origins of Wolbachia in ticks and their consequences on tick biology (known to be very diverse in invertebrates, ranging from nutritional symbionts in nematodes to reproductive manipulators in insects) are unknown. Here we report that the endoparasitoid wasp Ixodiphagus hookeri (Hymenoptera, Chalcidoidea, Encyrtidae) – strictly associated with ticks for their development - is infested at almost 100% prevalence by a W. pipientis strain belonging to a Wolbachia supergroup that has already been reported as associated with other hymenopteran parasitoids. In a natural population of I. ricinus that suffers high parasitism rates due to I. hookeri, we used specific PCR primers for both hymenopteran and W. pipientis gene fragments to show that all unfed tick nymphs parasitized by I. hookeri also harbored Wolbachia, while unparasitized ticks were Wolbachia-free. We demonstrated experimentally that unfed nymphs obtained from larvae exposed to I. hookeri while gorging on their vertebrate host also harbor Wolbachia. We hypothesize that previous studies that have reported W. pipientis in ticks are due to the cryptic presence of the endoparasitoid wasp I. hookeri. This association has remained hidden until now because parasitoids within ticks cannot be detected until engorgement of the nymphs brings the wasp eggs out of diapause. Finally, we discuss the consequences of this finding for our understanding of the tick microbiome, and their possible role in horizontal gene transfer among pathogenic and symbiotic bacteria

An international collaborative evaluation of central serous chorioretinopathy: different therapeutic approaches and review of literature. The European Vitreoretinal Society central serous chorioretinopathy study

Purpose: To study and compare the efficacy of different therapeutic options for the treatment of central serous chorioretinopathy (CSCR). Methods: This is a nonrandomized, international multicentre study on 1719 patients (1861 eyes) diagnosed with CSCR, from 63 centres (24 countries). Reported data included different methods of treatment and both results of diagnostic examinations [fluorescein angiography and/or optical coherent tomography (OCT)] and best-corrected visual acuity (BCVA) before and after therapy. The duration of observation had a mean of 11&nbsp;months but was extended in a minority of cases up to 7&nbsp;years. The aim of this study is to evaluate the efficacy of the different therapeutic options of CSCR in terms of both visual (BCVA) and anatomic (OCT) improvement. Results: One thousand seven hundred nineteen patients (1861 eyes) diagnosed with CSCR were included. Treatments performed were nonsteroidal anti-inflammatory eye drops, laser photocoagulation, micropulse diode laser photocoagulation, photodynamic therapy (PDT; Standard PDT, Reduced-dose PDT, Reduced-fluence PDT), intravitreal (IVT) antivascular endothelial growth factor injection (VEGF), observation and other treatments. The list of the OTHERS included both combinations of the main proposed treatments or a variety of other treatments such as eplerenone, spironolactone, acetazolamide, beta-blockers, anti-anxiety drugs, aspirin, folic acid, methotrexate, statins, vitis vinifera extract medication and pars plana vitrectomy. The majority of the patients were men with a prevalence of 77%. The odds ratio (OR) showed a partial or complete resolution of fluid on OCT with any treatment as compared with observation. In univariate analysis, the anatomical result (improvement in subretinal fluid using OCT at 1&nbsp;month) was favoured by age &lt;60&nbsp;years (p&nbsp;&lt;&nbsp;0.005), no previous observation (p&nbsp;&lt;&nbsp;0.0002), duration less than 3&nbsp;months (p&nbsp;&lt;&nbsp;0.0001), absence of CSCR in the fellow eye (p&nbsp;=&nbsp;0.04), leakage outside of the arcade (p&nbsp;=&nbsp;0.05) and fluid height &gt;500&nbsp;\u3bcm (p&nbsp;=&nbsp;0.03). The OR for obtaining partial or complete resolution showed that anti-VEGF and eyedrops were not statistically significant; whereas PDT (8.5), thermal laser (11.3) and micropulse laser (8.9) lead to better anatomical results with less variability. In univariate analysis, the functional result at 1&nbsp;month was favoured by first episode (p&nbsp;=&nbsp;0.04), height of subretinal fluid &gt;500&nbsp;\u3bcm (p&nbsp;&lt;&nbsp;0.0001) and short duration of observation (p&nbsp;=&nbsp;0.02). Finally, there was no statistically significant difference among the treatments at 12&nbsp;months. Conclusion: Spontaneous resolution has been described in a high percentage of patients. Laser (micropulse and thermal) and PDT seem to lead to significant early anatomical improvement; however, there is little change beyond the first month of treatment. The real visual benefit needs further clarification

Regulation of colony-stimulating factor 1-induced proliferation by heterotrimeric Gi2 proteins

Receptors for hematopoietic cytokines possess intrinsic tyrosine- kinases or are associated with tyrosine-kinases; interactions between metabolic pathways activated by tyrosine-kinases and heterotrimeric G proteins are suspected, but not yet proven. To investigate whether alteration of G protein function affects signal transduction of hematopoietic cytokines, we expressed mutant Gi2 proteins in BAC 1.2F5 cells, a murine macrophage cell line that is dependent from monocyte- macrophage colony-stimulating factor (CSF 1) for its proliferation. Mutations made in alpha subunits constitutively activate (alpha i2- Q205L) or inactivate (alpha i2-G204A) Gi2 heterotrimers. We show that expression of alpha i2-Q205L in BAC 1.2F5 cells does not induce independence from CSF 1, but reduces the cells' requirement in CSF 1, shortens the length of the G1 phase and the cell doubling time in response to CSF 1, and protects cells from death by apoptosis induced by CSF 1 withdrawal, exposure to H2O2 or heat shock, but not mitoxantrone. More importantly, expression of alpha i2-G204A, a dominant negative mutant, inhibits BAC 1.2F5 cell proliferation in response to CSF 1, increases the length of the G1 phase and the cell doubling time, and accelerates apoptotic cell death after withdrawal of CSF 1, exposure to H2O2 or heat shock. We conclude that the metabolic pathways regulated by Gi2 proteins and CSF 1 tyrosine-kinase receptors converge on a common effector necessary for the regulation of macrophage survival and proliferation.</jats:p

Reduction of adenylyl cyclase activity by cholera toxin in myeloid cells Long-term down-regulation of Gsα subunits by cholera toxin treatment

AbstractIn IPC-81 cells, the adenylyl-cyclase activation by cholera toxin produces an elevation of cAMP that causes a rapid cytolysis. A resistant clone with deficient cholera toxin-induced cyclase activity (yet sensitive to cAMP) showed a rapid decrease in the amount of membrane-bound Gsα (42–47 kDa) detectable soon after ADP-ribosylation of these proteins; pertussis toxin-sensitive G proteins (41 kDa) were not affected. Resistant cells showed a rapid decrease of Gsα that is consistent with the finding that cAMP did not accumulate in these cells. Cholera toxin treatment of resistant cells had long-lasting effects (several weeks) on the level of Gsα in the cell membrane. The duration of Gsα decrease does not correspond to the probable life of catalytically active cholera toxin in the cells, and suggests a regulated process more complex than a proteolytic degradation targeted on ADP-ribosylated molecules