Cutting edge: IL-1α is a crucial danger signal triggering acute myocardial inflammation during myocardial infarction.

Myocardial infarction (MI) induces a sterile inflammatory response that contributes to adverse cardiac remodeling. The initiating mechanisms of this response remain incompletely defined. We found that necrotic cardiomyocytes released a heat-labile proinflammatory signal activating MAPKs and NF-κB in cardiac fibroblasts, with secondary production of cytokines. This response was abolished in Myd88(-/-) fibroblasts but was unaffected in nlrp3-deficient fibroblasts. Despite MyD88 dependency, the response was TLR independent, as explored in TLR reporter cells, pointing to a contribution of the IL-1 pathway. Indeed, necrotic cardiomyocytes released IL-1α, but not IL-1β, and the immune activation of cardiac fibroblasts was abrogated by an IL-1R antagonist and an IL-1α-blocking Ab. Moreover, immune responses triggered by necrotic Il1a(-/-) cardiomyocytes were markedly reduced. In vivo, mice exposed to MI released IL-1α in the plasma, and postischemic inflammation was attenuated in Il1a(-/-) mice. Thus, our findings identify IL-1α as a crucial early danger signal triggering post-MI inflammation.

Role and regulation of islet-Brain 1 in pancreatic β-cells

Résumé : L'insuline est produite et sécrétée par la cellule ß-pancréatique. Son rôle est de régler le taux de sucre dans le sang. Si ces cellules meurent ou échouent à produire suffisamment de l'insuline, les sujets développent le diabète de type 2 (DT2), une des maladies les plus communes dans les pays développés. L'excès chronique des lipoprotéines LDL oxydés (oxLDL) et/ou des cytokines pro-inflammatoires comme l'interleukine-1ß (IL-1ß) participent au dérèglement et à la mort des cellules ß. Nous avons montré qu'une chute des niveaux d'expression de la protéine nommée «mitogen activated protein kinase 8 interacting protein 1» ou «islet brain 1 (IB 1)» est en partie responsable des effets provoqués par les oxLDL ou IL-1ß. IB1 régule l'expression de l'insuline et la survie cellulaire en inhibant la voie de signalisation « c-jun N-terminal Kinase (JNK)». La réduction des niveaux d'expression d'IB1 provoque l'activation de la voie JNK en réponse aux facteurs environnementaux, et ainsi initie la réduction de l'expression de l'insuline et l'induction du programme de mort cellulaire. Les mimétiques de l'hormone "Glucagon-like peptide 1", tel que l'exendin-4 (ex-4), sont une nouvelle classe d'agents hypoglycémiants utilisés dans le traitement du DT2. Les effets bénéfiques de l'ex-4 sont en partie accomplis en préservant l'expression de l'insuline et la survie des cellules ß contre les stress associés au DT2. La restauration des niveaux d'expression d'IB1 est un des mécanismes par lequel l'ex-4 prodigue son effet sur la cellule. En effet, cette molécule stimule l'activité du promoteur du gène et ainsi compense la réduction du contenu en IB1 causée par le stress. Outre ce rôle anti-apoptotique, dans ce travail de thèse nous avons mis en évidence une autre fonction d'IB1 dans la cellule ß. La réduction de l'activité ou des niveaux d'expression d'IB1 induisent une réduction importante de la sécrétion de l'insuline en réponse au glucose. Le mécanisme par lequel IB1 régule la sécrétion de l'insuline implique à la fois le métabolisme du glucose et éventuellement le transport vésiculaire en contrôlant l'expression de la protéine annexin A2. En résumé, IB 1 est une molécule clé à travers laquelle l'environnement du diabétique pourrait exercer un effet délétère sur la cellule ß. L'amélioration de l'activité d'IB1 et/ou de son expression devrait être considérée dans les approches thérapeutiques futures visant à limiter la perte des cellules ß dans le diabète. Abstract : ß-cells of the pancreatic islets of Langerhans produce and secrete insulin when blood glucose rises. In turn, insulin ensures that plasma glucose concentrations return within a relatively narrow physiological range. If ß-cells die or fail to produce enough insulin, individuals develop one of the most common diseases in Western countries, namely type 2 diabetes (T2D). Chronic excess of oxidized low density lipoproteins (oxLDL) and/or pro-inflammatory cytokines such as interleukin 1-ß (IL-1ß) contribute to decline of ß-cells and thereby are thought to accelerate progression of the disease overtime. We showed that profound reduction in the levels of the mitogen activated protein kinase 8 interacting protein 1 also called islet brain 1 (IB1) causes ß-cell failure accomplished by oxLDL or IL-1 ß. IB1 regulates insulin expression and cell survivals by inhibiting the c-Jun N-terminal Kinase pathway. Diminution in IB 1 levels leads to an increase in activation of the JNK pathway induced by environmental stressors, and thus initiates loss of insulin expression and programmed cell death. The mimetic agents of the glucoincretin glucagon-like peptide 1 such as exendin-4 (ex-4) are new class of hypoglycaemic medicines for treatment of T2D. The beneficial property is in part achieved by preserving insulin expression and ß-cell survival against stressors related to diabetes. Restored levels in IB 1 account for the cytoprotective effect of the ex-4. In fact, the latter molecule .stimulates the promoter activity of the gene and thus compensates loss of IB1 content triggered by stress. Beside of the anti-apoptotic role, an additional leading function for IB 1 in ß-cells was highlighted in this thesis. Impairment in IB1 activity or silencing of the gene in ß-cells revealed a major reduction in insulin secretion elicited by glucose. The mechanisms whereby IB 1 couples glucose to insulin release involve glucose metabolism and potentially, vesicles trafficking by maintaining the levels of annexin A2. IB 1 is therefore a key molecule through which environmental factors related to diabetes may exert harmful effects on ß-cells. Improvement in IB 1 activity and/or expression should be considered as a target for therapeutic purpose.

Determination of chlorzoxazone and 6-hydroxychlorzoxazone in plasma by gas chromatography--mass spectrometry.

A gas chromatographic-mass spectrometric method is presented which allows the determination of chlorzoxazone and 6-hydroxychlorzoxazone after derivatization with the reagent N-tert.-butyldimethylsilyl-N-methyltrifluoroacetamide. No interference was observed from endogenous compounds following the extraction of plasma samples from six different human subjects. The standard curves were linear over a working range of 20 to 4000 ng/ml and of 20 to 1000 ng/ml for chlorzoxazone and 6-hydroxychlorzoxazone, respectively. Recoveries ranged from 65 to 97% for the two compounds and intra- and inter-day coefficients of variation were always less than 9%. The limit of quantitation of the method was found to be 5 ng/ml for the two compounds, hence allowing its use for single low dose pharmacokinetics.

Incretin receptor null mice reveal key role of GLP-1 but not GIP in pancreatic beta cell adaptation to pregnancy.

Islet adaptations to pregnancy were explored in C57BL6/J mice lacking functional receptors for glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP). Pregnant wild type mice and GIPRKO mice exhibited marked increases in islet and beta cell area, numbers of medium/large sized islets, with positive effects on Ki67/Tunel ratio favouring beta cell growth and enhanced pancreatic insulin content. Alpha cell area and glucagon content were unchanged but prohormone convertases PC2 and PC1/3 together with significant amounts of GLP-1 and GIP were detected in alpha cells. Knockout of GLP-1R abolished these islet adaptations and paradoxically decreased pancreatic insulin, GLP-1 and GIP. This was associated with abolition of normal pregnancy-induced increases in plasma GIP, L-cell numbers, and intestinal GIP and GLP-1 stores. These data indicate that GLP-1 but not GIP is a key mediator of beta cell mass expansion and related adaptations in pregnancy, triggered in part by generation of intra-islet GLP-1.

Synchrotron-based X-ray tomographic microscopy for rock physics investigations

Synchrotron radiation X-ray tomographic microscopy is a nondestructive method providing ultra-high-resolution 3D digital images of rock microstructures. We describe this method and, to demonstrate its wide applicability, we present 3D images of very different rock types: Berea sandstone, Fontainebleau sandstone, dolomite, calcitic dolomite, and three-phase magmatic glasses. For some samples, full and partial saturation scenarios are considered using oil, water, and air. The rock images precisely reveal the 3D rock microstructure, the pore space morphology, and the interfaces between fluids saturating the same pore. We provide the raw image data sets as online supplementary material, along with laboratory data describing the rock properties. By making these data sets available to other research groups, we aim to stimulate work based on digital rock images of high quality and high resolution. We also discuss and suggest possible applications and research directions that can be pursued on the basis of our data.

Correlation between plasma concentration of cilazapril and haemodynamic and hormonal effects in healthy man.

1. The haemodynamic and humoral effects of cilazapril, a new angiotensin converting enzyme (ACE) inhibitor, were evaluated in normotensive healthy volunteers. 2. Single oral doses of 1.25, 2.5, 5 and 10 mg of cilazapril inhibited ACE by greater than or equal to 90% and induced the expected pattern of changes of the renin-angiotensin-aldosterone-system. 3. Cilazapril had a long duration of action, since some ACE inhibition was still present 72 h after drug intake. 4. Cilazapril administered intravenously at doses of 5 and 20 micrograms kg-1 for 24 h did not produce any significant effects. 5. During repeated administration of cilazapril for 8 days, no accumulation of cilazaprilat was observed and the clinical tolerance was excellent. 6. In normal volunteers, cilazapril administered orally acts as a potent inhibitor of converting enzyme.

Plasma and urine profiles of Delta9-tetrahydrocannabinol and its metabolites 11-hydroxy-Delta9-tetrahydrocannabinol and 11-nor-9-carboxy-Delta9-tetrahydrocannabinol after cannabis smoking by male volunteers to estimate recent consumption by athletes.

Since 2004, cannabis has been prohibited by the World Anti-Doping Agency for all sports competitions. In the years since then, about half of all positive doping cases in Switzerland have been related to cannabis consumption. In doping urine analysis, the target analyte is 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH), the cutoff being 15 ng/mL. However, the wide urinary detection window of the long-term metabolite of Delta(9)-tetrahydrocannabinol (THC) does not allow a conclusion to be drawn regarding the time of consumption or the impact on the physical performance. The purpose of the present study on light cannabis smokers was to evaluate target analytes with shorter urinary excretion times. Twelve male volunteers smoked a cannabis cigarette standardized to 70 mg THC per cigarette. Plasma and urine were collected up to 8 h and 11 days, respectively. Total THC, 11-hydroxy-Delta(9)-tetrahydrocannabinol (THC-OH), and THC-COOH were determined after hydrolysis followed by solid-phase extraction and gas chromatography/mass spectrometry. The limits of quantitation were 0.1-1.0 ng/mL. Eight puffs delivered a mean THC dose of 45 mg. Plasma levels of total THC, THC-OH, and THC-COOH were measured in the ranges 0.2-59.1, 0.1-3.9, and 0.4-16.4 ng/mL, respectively. Peak concentrations were observed at 5, 5-20, and 20-180 min. Urine levels were measured in the ranges 0.1-1.3, 0.1-14.4, and 0.5-38.2 ng/mL, peaking at 2, 2, and 6-24 h, respectively. The times of the last detectable levels were 2-8, 6-96, and 48-120 h. Besides high to very high THC-COOH levels (245 +/- 1,111 ng/mL), THC (3 +/- 8 ng/mL) and THC-OH (51 +/- 246 ng/mL) were found in 65 and 98% of cannabis-positive athletes' urine samples, respectively. In conclusion, in addition to THC-COOH, the pharmacologically active THC and THC-OH should be used as target analytes for doping urine analysis. In the case of light cannabis use, this may allow the estimation of more recent consumption, probably influencing performance during competitions. However, it is not possible to discriminate the intention of cannabis use, i.e., for recreational or doping purposes. Additionally, pharmacokinetic data of female volunteers are needed to interpret cannabis-positive doping cases of female athletes.

HIV-1 coreceptor usage and CXCR4-specific viral load predict clinical disease progression during combination antiretroviral therapy

Background: Although combination antiretroviral therapy (cART) dramatically reduces rates of AIDS and death, a minority of patients experience clinical disease progression during treatment. <p>Objective: To investigate whether detection of CXCR4(X4)-specific strains or quantification of X4-specific HIV-1 load predict clinical outcome. Methods: From the Swiss HIV Cohort Study, 96 participants who initiated cART yet subsequently progressed to AIDS or death were compared with 84 contemporaneous, treated nonprogressors. A sensitive heteroduplex tracking assay was developed to quantify plasma X4 and CCR5 variants and resolve HIV-1 load into coreceptor-specific components. Measurements were analyzed as cofactors of progression in multivariable Cox models adjusted for concurrent CD4 cell count and total viral load, applying inverse probability weights to adjust for sampling bias. Results: Patients with X4 variants at baseline displayed reduced CD4 cell responses compared with those without X4 strains (40 versus 82 cells/mu l; P= 0.012). The adjusted multivariable hazard ratio (HR) for clinical progression was 4.8 [95% confidence interval (Cl) 2.3-10.0] for those demonstrating X4 strains at baseline. The X4-specific HIV-1 load was a similarly independent predictor, with HR values of 3.7(95%Cl, 1.2-11.3) and 5.9 (95% Cl, 2.2-15.0) for baseline loads of 2.2-4.3 and > 4.3 log(10)copies/ml, respectively, compared with < 2.2 log(10)copies/ml. Conclusions: HIV-1 coreceptor usage and X4-specific viral loads strongly predicted disease progression during cART, independent of and in addition to CD4 cell count or total viral load. Detection and quantification of X4 strains promise to be clinically useful biomarkers to guide patient management and study HIV-1 pathogenesis.

Imatinib plasma concentrations variability in oncologic patients

Imatinib (Glivec®) has transformed the treatment and short-term prognosis of chronic myeloid leukemia (CML) and gastrointestinal stromal tumor (GIST). However, the treatment must be taken indefinitely, it is not devoid of inconvenience and toxicity. Moreover, resistance or escape from disease control occurs in a significant number of patients. Imatinib is a substrate of the cytochromes P450 CYP3A4/5 and of the multidrug transporter P-glycoprotein (product of the MDR1 gene). Considering the large inter-individual differences in the expression and function of those systems, the disposition and clinical activity of imatinib can be expected to vary widely among patients, calling for dosage individualization. The aim of this exploratory study was to determine the average pharmacokinetic parameters characterizing the disposition of imatinib in the target population, to assess their inter-individual variability, and to identify influential factors affecting them. A total of 321 plasma concentrations, taken at various sampling times after the latest dose, were measured in 59 patients receiving Glivec at diverse regimens, using a validated HPLC-UV method developed for this study. The results were analyzed by non-linear mixed effect modeling (NONMEM). A one-compartment model with first-order absorption appeared appropriate to describe the data, with an average apparent clearance of 12.4 l/h, a distribution volume of 268 l and an absorption constant of 0.47 h-1. The clearance was affected by body weight, age and sex. No influences of interacting drugs were found. DNA samples were used for pharmacogenetic explorations. At present, only the MDR1 polymorphism has been assessed and seems to affect the pharmacokinetic parameters of imatinib. Large inter-individual variability remained unexplained by the demographic covariates considered, both on clearance (40 %) and distribution volume (71 %). Together with intra-patient variability (34 %), this translates into an 8-fold width of the 90 %-prediction interval of plasma concentrations expected under a fixed dosing regimen. This is a strong argument to further investigate the possible usefulness of a therapeutic drug monitoring program for imatinib. It may help to individualize the dosing regimen before overt disease progression or observation of treatment toxicity, thus improving both the long-term therapeutic effectiveness and tolerability of this drug.

A phosphorylation cycle shapes gradients of the DYRK family kinase Pom1 at the plasma membrane.

Concentration gradients regulate many cell biological and developmental processes. In rod-shaped fission yeast cells, polar cortical gradients of the DYRK family kinase Pom1 couple cell length with mitotic commitment by inhibiting a mitotic inducer positioned at midcell. However, how Pom1 gradients are established is unknown. Here, we show that Tea4, which is normally deposited at cell tips by microtubules, is both necessary and, upon ectopic cortical localization, sufficient to recruit Pom1 to the cell cortex. Pom1 then moves laterally at the plasma membrane, which it binds through a basic region exhibiting direct lipid interaction. Pom1 autophosphorylates in this region to lower lipid affinity and promote membrane release. Tea4 triggers Pom1 plasma membrane association by promoting its dephosphorylation through the protein phosphatase 1 Dis2. We propose that local dephosphorylation induces Pom1 membrane association and nucleates a gradient shaped by the opposing actions of lateral diffusion and autophosphorylation-dependent membrane detachment.

Relationship of imatinib-free plasma levels and target genotype with efficacy and tolerability

Imatinib has revolutionised the treatment of chronic myeloid leukaemia (CML) and gastrointestinal stromal tumours (GIST). Using a nonlinear mixed effects population model, individual estimates of pharmacokinetic parameters were derived and used to estimate imatinib exposure (area under the curve, AUC) in 58 patients. Plasma-free concentration was deduced from a model incorporating plasma levels of alpha(1)-acid glycoprotein. Associations between AUC (or clearance) and response or incidence of side effects were explored by logistic regression analysis. Influence of KIT genotype was also assessed in GIST patients. Both total (in GIST) and free drug exposure (in CML and GIST) correlated with the occurrence and number of side effects (e.g. odds ratio 2.7+/-0.6 for a two-fold free AUC increase in GIST; P<0.001). Higher free AUC also predicted a higher probability of therapeutic response in GIST (odds ratio 2.6+/-1.1; P=0.026) when taking into account tumour KIT genotype (strongest association in patients harbouring exon 9 mutation or wild-type KIT, known to decrease tumour sensitivity towards imatinib). In CML, no straightforward concentration-response relationships were obtained. Our findings represent additional arguments to further evaluate the usefulness of individualizing imatinib prescription based on a therapeutic drug monitoring programme, possibly associated with target genotype profiling of patients.

Plasma and cerebrospinal fluid population pharmacokinetics of temozolomide in malignant glioma patients

RESUME : Objectif: Le glioblastome multiforme (GBM) est la tumeur cérébrale maligne la plus agressive qui conduit au décès de la majorité des patients moins d'une année après le diagnostic. La plupart des agents chimiothérapeutiques actuellement disponibles ne traversent pas la barrière hémato¬encéphalique et ne peuvent par conséquent pas être utilisés pour ce type de tumeur. Le Temozolomide (TMZ) est un nouvel agent alkylant récemment développé pour le traitement des gliomes malins. A ce jour, très peu d'informations sont disponibles sur la pénétration intra-cérébrale de cet agent. Au cours d'une étude pilote de phase II menée auprès de 64 patients atteints de GBM, l'administration précoce de TMZ combinée à une radiothérapie standard (RT) afin d'intervenir au plus tôt dans l'évolution de la maladie, a permis de prolonger la survie de ces patients, résultat qui pu être confirmé par la suite lors de l'étude randomisée de phase III. L'objectif de cette étude a été de déterminer les paramètres pharmacocinétique du TMZ dans le plasma et le liquide céphalo-rachidien (LCR), d'évaluer l'influence de certains facteurs individuels (âge, sexe, surface corporelle, fonction rénale/hépatique, co-médications, RT concomitante) sur ces différents paramètres, et enfin d'explorer la relation existant entre l'exposition au TMZ et certains marqueurs cliniques d'efficacité et de toxicité. Matériel et Méthode: Les concentrations de TMZ ont été mesurées par chromatographie liquide à haute performance (HPLC) dans le plasma et le LCR de 35 patients atteints de GBM nouvellement diagnostiqués (étude pilote) ou de gliomes malins en récidive (étude récidive). L'analyse pharmacocinétique de population a été réalisée à l'aide du programme NONMEM. L'exposition systémique et cérébrale, définie par les AUC (Area Under the time-concentration Curve) dans le plasma et le LCR, a été estimée pour chaque patient et corrélée à la toxicité, la survie ainsi que la survie sans progression tumorale. Résultats: Un modèle à 1 compartiment avec une cinétique d'absorption et de transfert Kplasma -> LCR de ordre a été retenu afin de décrire le profil pharmacocinétique du TMZ. Les valeurs moyennes de population ont été de 10 L/h pour la clairance, de 30.3 L pour le volume de distribution, de 2.1 h pour la 1/2 vie d'élimination, de 5.78 hE-1 pour la constante d'absorption, de 7.2 10E4 hE-1 pour Kplasma->LCR et de 0.76 hE-1 pour KLCR plasma. La surface corporelle a montré une influence significative sur la clairance et le volume de distribution, alors que le sexe influence la clairance uniquement. L'AUC mesurée dans le LCR représente ~20% de celle du plasma et une augmentation de 15% de Kplasma->LCR a été observée lors du traitement concomitant de radiochimiothérapie. Conclusions: Cette étude est la première analyse pharmacocinétique effectuée chez l'homme permettant de quantifier la pénétration intra-cérébrale du TMZ. Le rapport AUC LCR/AUC Plasma a été de 20%. Le degré d'exposition systémique et cérébral au TMZ ne semble pas être un meilleur facteur prédictif de la survie ou de la tolérance au produit que ne l'est la dose cumulée seule. ABSTRACT Purpose: Scarce information is available on the brain penetration of temozolomide (TMZ), although this novel methylating agent is mainly used for the treatment of ma¬lignant brain tumors. The purpose was to assess TNIZ phar¬macokinetics in plasma and cerebrospinal fluid (CSF) along with its inter-individual variability, to characterize covari¬ates and to explore relationships between systemic or cere¬bral drug exposure and clinical outcomes. Experimental Design: TMZ levels were measured by high-performance liquid chromatography in plasma and CSF samples from 35 patients with newly diagnosed or recurrent malignant gliomas. The population pharmacoki¬netic analysis was performed with nonlinear mixed-effect modeling software. Drug exposure, defined by the area un¬der the concentration-time curve (AUC) in plasma and CSF, was estimated for each patient and correlated with toxicity, survival, and progression-free survival. Results: A three-compartment model with first-order absorption and transfer rates between plasma and CSF described the data appropriately. Oral clearance was 10 liter/h; volume of distribution (VD), 30.3 liters; absorption constant rate, 5.8 hE-1; elimination half-time, 2.1 h; transfer rate from plasma to CSF (Kplasma->CSF), 7.2 x 10E-4hE-1 and the backwards rate, 0.76hE-1. Body surface area signifi¬cantly influenced both clearance and VD, and clearance was sex dependent. The AU CSF corresponded to 20% of the AUCplasma. A trend toward an increased K plasma->CSF of 15% was observed in case of concomitant radiochemo-therapy. No significant correlations between AUC in plasma or CSF and toxicity, survival, or progression-free survival were apparent after deduction of dose-effect. Conclusions: This is the first human pharmacokinetic study on TMZ to quantify CSF penetration. The AUC CSF/ AUC plasma ratio was 20%. Systemic or cerebral exposures are not better predictors than the cumulative dose alone for both efficacy and safety.

Blood plasma lipidomic signature of epicardial fat in healthy obese women.

OBJECTIVES: A lipidomic approach was employed in a clinically well-defined cohort of healthy obese women to explore blood lipidome phenotype ascribed to body fat deposition, with emphasis on epicardial adipose tissue (EAT). METHODS: The present investigation delivered a lipidomics signature of epicardial adiposity under healthy clinical conditions using a cohort of 40 obese females (age: 25-45 years, BMI: 28-40 kg/m(2) ) not showing any metabolic disease traits. Lipidomics analysis of blood plasma was employed in combination with in vivo quantitation of mediastinal fat depots by computerized tomography. RESULTS: All cardiac fat depots correlated to indicators of hepatic dysfunctions (ALAT and ASAT), which describe physiological connections between hepatic and cardiac steatosis. Plasma lipidomics encompassed overall levels of lipid classes, fatty acid profiles, and individual lipid species. EAT and visceral fat associated with diacylglycerols (DAG), triglycerides, and distinct phospholipid and sphingolipid species. A pattern of DAG and phosphoglycerols was specific to EAT. CONCLUSIONS: Human blood plasma lipidomics appears to be a promising clinical and potentially diagnostic readout for patient stratification and monitoring. Association of blood lipidomics signature to regio-specific mediastinal and visceral adiposity under healthy clinical conditions may help provide more biological insights into obese patient stratification for cardiovascular disease risks.

PHYTOCHROME KINASE SUBSTRATE 1 is a phototropin 1 binding protein required for phototropism.

Phototropism, or plant growth in response to unidirectional light, is an adaptive response of crucial importance. Lateral differences in low fluence rates of blue light are detected by phototropin 1 (phot1) in Arabidopsis. Only NONPHOTOTROPIC HYPOCOTYL 3 (NPH3) and root phototropism 2, both belonging to the same family of proteins, have been previously identified as phototropin-interacting signal transducers involved in phototropism. PHYTOCHROME KINASE SUBSTRATE (PKS) 1 and PKS2 are two phytochrome signaling components belonging to a small gene family in Arabidopsis (PKS1-PKS4). The strong enhancement of PKS1 expression by blue light and its light induction in the elongation zone of the hypocotyl prompted us to study the function of this gene family during phototropism. Photobiological experiments show that the PKS proteins are critical for hypocotyl phototropism. Furthermore, PKS1 interacts with phot1 and NPH3 in vivo at the plasma membrane and in vitro, indicating that the PKS proteins may function directly with phot1 and NPH3 to mediate phototropism. The phytochromes are known to influence phototropism but the mechanism involved is still unclear. We show that PKS1 induction by a pulse of blue light is phytochrome A-dependent, suggesting that the PKS proteins may provide a molecular link between these two photoreceptor families.

Origin of minority drug-resistant HIV-1 variants in primary HIV-1 infection.

BACKGROUND: Drug-resistant human immunodeficiency virus type 1 (HIV-1) minority variants (MVs) are present in some antiretroviral therapy (ART)-naive patients. They may result from de novo mutagenesis or transmission. To date, the latter has not been proven. METHODS: MVs were quantified by allele-specific polymerase chain reaction in 204 acute or recent seroconverters from the Zurich Primary HIV Infection study and 382 ART-naive, chronically infected patients. Phylogenetic analyses identified transmission clusters. RESULTS: Three lines of evidence were observed in support of transmission of MVs. First, potential transmitters were identified for 12 of 16 acute or recent seroconverters harboring M184V MVs. These variants were also detected in plasma and/or peripheral blood mononuclear cells at the estimated time of transmission in 3 of 4 potential transmitters who experienced virological failure accompanied by the selection of the M184V mutation before transmission. Second, prevalence between MVs harboring the frequent mutation M184V and the particularly uncommon integrase mutation N155H differed highly significantly in acute or recent seroconverters (8.2% vs 0.5%; P < .001). Third, the prevalence of less-fit M184V MVs is significantly higher in acutely or recently than in chronically HIV-1-infected patients (8.2% vs 2.5%; P = .004). CONCLUSIONS: Drug-resistant HIV-1 MVs can be transmitted. To what extent the origin-transmission vs sporadic appearance-of these variants determines their impact on ART needs to be further explored.