An update on molecular cat allergens: Fel d 1 and what else? Chapter 1: Fel d 1, the major cat allergen.

BACKGROUND: Cats are the major source of indoor inhalant allergens after house dust mites. The global incidence of cat allergies is rising sharply, posing a major public health problem. Ten cat allergens have been identified. The major allergen responsible for symptoms is Fel d 1, a secretoglobin and not a lipocalin, making the cat a special case among mammals. MAIN BODY: Given its clinical predominance, it is essential to have a good knowledge of this allergenic fraction, including its basic structure, to understand the new exciting diagnostic and therapeutic applications currently in development. The recent arrival of the component-resolved diagnosis, which uses molecular allergens, represents a unique opportunity to improve our understanding of the disease. Recombinant Fel d 1 is now available for in vitro diagnosis by the anti-Fel d 1 specific IgE assay. The first part of the review will seek to describe the recent advances related to Fel d 1 in terms of positive diagnosis and assessment of disease severity. In daily practice, anti-Fel d 1 IgE tend to replace those directed against the overall extract but is this attitude justified? We will look at the most recent arguments to try to answer this question. In parallel, a second revolution is taking place thanks to molecular engineering, which has allowed the development of various forms of recombinant Fel d 1 and which seeks to modify the immunomodulatory properties of the molecule and thus the clinical history of the disease via various modalities of anti-Fel d 1-specific immunotherapy. We will endeavor to give a clear and practical overview of all these trends.

The cell division control protein 42-Src family kinase-neural Wiskott-Aldrich syndrome protein pathway regulates human proplatelet formation.

Essentials The role of the cytoskeleton during megakaryocyte differentiation was examined. Human megakaryocytes are derived from in vitro cultured CD34+ cells. Cell division control protein 42 (CDC42) positively regulates proplatelet formation (PPF). Neural Wiskott-Aldrich syndrome protein, the main effector of CDC42 with Src positively regulates PPF. SUMMARY: Background Cytoskeletal rearrangements are essential for platelet release. The RHO small GTPase family, as regulators of the actin cytoskeleton, play an important role in proplatelet formation (PPF). In the neuronal system, CDC42 is involved in axon formation, a process that combines elongation and branching as for PPF. Objective To analyze the role of CDC42 and its effectors of the Wiskott-Aldrich syndrome protein (WASP) family in PPF. Methods Human megakaryocytes (MKs) were obtained from CD34+ cells. Inhibition of CDC42 in MKs was performed with the chemical inhibitor CASIN or with an active or a dominant-negative form of CDC42. The knock-down of N-WASP was obtained with a small hairpin RNA strategy Results Herein, we show that CDC42 activity increased during MK differentiation. The use of the chemical inhibitor CASIN or of an active or a dominant-negative form of CDC42 demonstrated that CDC42 positively regulated PPF in vitro. We determined that N-WASP, but not WASP, regulated PPF. We found that N-WASP knockdown led to a marked decrease in PPF, owing to a defect in the demarcation membrane system (DMS). This was associated with RHOA activation, and a concomitant augmentation in the phosphorylation of mysosin light chain 2. Phosphorylation of N-WASP, creating a primed form of N-WASP, increased during MK differentiation. Phosphorylation inhibition by two Src family kinase inhibitors decreased PPF. Conclusions We conclude that N-WASP positively regulates DMS development and PPF, and that the Src family kinases in association with CDC42 regulate PPF through N-WASP.

Competitive adsorption of toxic metals on bentonite and use of chitosan as flocculent coagulant to speed up the settling of generated clay suspensions.

Evaluation of modified Algerian clay as mineral adsorbent was done for its adsorbing capacity on copper (Cu) and Zinc (Zn) cations. The results obtained show a rapid kinetic adsorption for both metals (less than 2 h) following the pseudo-second order model with high elimination rates of 67.2 and 61.8% for Cu and Zn respectively. The adsorption isotherms analyzed with Langmuir model revealed a correlation with the experimental values. While the use of obtained chitosan at room temperature, as flocculent coagulant, accelerates the decantation of the colloidal particles in suspension generated after adsorption process.

Thrombocytopenia induced by the histone deacetylase inhibitor abexinostat involves p53-dependent and -independent mechanisms.

Abexinostat is a pan histone deacetylase inhibitor (HDACi) that demonstrates efficacy in malignancy treatment. Like other HDACi, this drug induces a profound thrombocytopenia whose mechanism is only partially understood. We have analyzed its effect at doses reached in patient plasma on in vitro megakaryopoiesis derived from human CD34(+) cells. When added at day 0 in culture, abexinostat inhibited CFU-MK growth, megakaryocyte (MK) proliferation and differentiation. These effects required only a short incubation period. Decreased proliferation was due to induction of apoptosis and was not related to a defect in TPO/MPL/JAK2/STAT signaling. When added later (day 8), the compound induced a dose-dependent decrease (up to 10-fold) in proplatelet (PPT) formation. Gene profiling from MK revealed a silencing in the expression of DNA repair genes with a marked RAD51 decrease at protein level. DNA double-strand breaks were increased as attested by elevated γH2AX phosphorylation level. Moreover, ATM was phosphorylated leading to p53 stabilization and increased BAX and p21 expression. The use of a p53 shRNA rescued apoptosis, and only partially the defect in PPT formation. These results suggest that HDACi induces a thrombocytopenia by a p53-dependent mechanism along MK differentiation and a p53-dependent and -independent mechanism for PPT formation.

Human recombinant myeloperoxidase antiviral activity on cytomegalovirus.

In vitro incubation of human cytomegalovirus (Towne strain) with 8 U/ml human recombinant myeloperoxidase plus sodium chloride and glucose nearly abolished viral infectivity. To assay the effect on intracellular infection, cell toxicity of the enzymes was first studied. Even the high dose of 16 U/ml of recombinant myeloperoxidase plus 10 mU/ml glucose oxidase did not decrease MRC5 cell growth. By contrast, this dose reduced proliferation of activated THP1 cells. Even half of the myeloperoxidase dose proved slightly toxic to these cells. Non-cytotoxic concentrations of the reagents were used to monitor their effect on cytomegalovirus infection. In MRC5 cells, even the low dose of 4 U/ml myeloperoxidase plus glucose oxidase inhibited synthesis of cytomegalovirus early antigens, as tested by immunofluorescence. Viral release in the supernatant was decreased by 4 logs. In THP1 cells, which produce endogenously hydrogen peroxide, myeloperoxidase alone (8 U/ml) decreased the formation of early and late antigens by 53 and 44%, respectively.

A human milk factor susceptible to cathepsin D inhibitors enhances human immunodeficiency virus type 1 infectivity and allows virus entry into a mammary epithelial cell line.

Human immunodeficiency virus type 1 (HIV-1) growth in lymphocyte cultures was increased when the virus inoculum was incubated in breast milk. The enhancing effect of milk was abolished by anti-cathepsin D antibody or by pepstatin A, a cathepsin D inhibitor. The cathepsin D-producing CD4-negative MCF7 mammary cells supported the growth of some HIV-1 isolates. An MCF7 line chronically producing HIV-1 IIIb was obtained. Cathepsin D may induce conformational modification of viral gp120, allowing direct interaction with a coreceptor. We demonstrated the presence of CXCR4 mRNA in MCF7 cells.

HIV-1 infectivity and host range modification by cathepsin D present in human vaginal secretions.

OBJECTIVE: To investigate HIV-1 infectivity in the natural environment of vaginal secretions. DESIGN: Vaginal wash samples collected from 14 healthy women were incubated in vitro with various HIV-1 strains for 10 min at 37 degrees C and then assayed for infectivity on primary lymphocyte cultures, or on CEM cells, or on CD4- ME180 cells derived from vaginal epithelium. METHODS: HIV-1 infectivity was measured by early virus growth in the various host cells tested using a quantitative p24 assay and by the Karber procedure. RESULTS: Preincubation of HIV-1(IIIB) with vaginal wash samples or 2 microg/ml cathepsin D increased the ability of the virus to grow in lymphocyte cultures. The vaginal wash effect was abolished by 5 microg/ml pepstatin A, an inhibitor of aspartyl proteases. Presence of precursor and mature forms of cathepsin D in vaginal wash was demonstrated after passage through a pepstatin A-agarose column. Median tissue culture infective doses of HIV-1(IIIB) and HIV-1(JRFL) strains were increased 14.4-fold and 18-fold, respectively, after preincubation in vaginal wash sample, and were increased by pretreatment with 2 microg/ml cathepsin D. When CD4 receptors of CEMss cells were blocked by OKT4a monoclonal antibody, the cells lost susceptibility to HIV-1 (IIIB), but supported the growth of virus pretreated with vaginal wash sample or cathepsin D. These treated viruses were able to initiate infection of CD4-ME180 epithelial cells, which were not receptive to untreated virus. ME180 cells were shown to possess the messenger of CXC-chemokine receptor-4. CONCLUSIONS: Vaginal secretions may help HIV-1 transmission to women by increasing infectivity for CD4+ cells and allowing entrance into some CD4-epithelial cells.

[Monitoring of intracranial pressure with intraparenchymal fiberoptic transducer. Technical aspects and clinical reliability]. / Monitorage de la pression intracrânienne par capteur intraparenchymateux à fibres optiques: aspects techniques et fiabilité clinique.

A fiberoptic intracranial pressure transducer (Camino) was assessed prospectively in 100 patients. In all, 122 sensors were inserted intraparenchymally at the bedside, without the help of a neurosurgeon. Before the procedure, patients were given 2 to 4 mg of phenoperidine. The scalp was opened over a few millimeters in the frontal paramedian area. A burr holc was made with a 2 mm bit. The dura mater was opened and a hollow screw inserted in the diploë. When the zero of the transducer had been obtained, a 5 cm length was inserted within the screw. The transducer was then about 5 mm deep within cerebral parenchyma. The procedure took an average of about 15 min. An intracerebral haematoma around the transducer occurred five times. One had to be drained surgically. There were no infectious complications. The daily baseline drift was about 0.3 mmHg. The system seemed to be reliable: there was close agreement between the intracranial pressure (ICP), neurological status and CT scan findings. In trauma cases, there was also good correlation between mean ICP and the basal cistern obliteration score, finally, ICP became equivalent to mean arterial blood pressure in all brain dead patients. It is concluded that this system may be used in all cases where ICP requires to be monitored, even when the lateral ventricles are no longer visible, or when craniotomy has been performed. This will most probably result in a more extended use of ICP monitoring in neurosurgical intensive care.