Characterization of a Novel Chemotactic Factor for Neutrophils in the Bronchial Secretions of Patients with Cystic Fibrosis

Chronic airway inflammation is a hallmark of cystic fibrosis (CF). Biological products with chemotactic activity are essential for neutrophil recruitment to sites of inflammation. The presence of a factor with chemotactic activity higher than that of interleukin (IL)-8 in the bronchial secretions of patients with CF has recently been reported. This article reports that the chemotactic activity of this factor remained unaffected by a variety of physical treatments and could be distinguished from those of IL-8, formylmethionylleucylphenylalanine, leukotreine B4, and platelet-activating factor. The factor induced chemotaxis and chemokinesis locomotion of neutrophils, and its chemotactic activity was sensitive to pertussis toxin and thapsigargin. Semipurified preparation of the chemotactic factor increased transiently intracellular Ca2+ concentration but failed to stimulate the release of neutrophil primary granules and the production of superoxide, suggesting that the semipurified chemotactic factor is a Ca2+-dependent chemoattractant of neutrophils, acting via pertussin toxin-sensitive G protein-coupled surface receptors, that directs neutrophil movement toward the airway epitheliu

Chemotactic Factors in Bronchial Secretions of Cystic Fibrosis Patients

To understand chronic neutrophil attraction into cystic fibrosis airways, both global chemotactic activity and individual chemotactic factors were studied in bronchial secretions. Bronchial secretions of 8 cystic fibrosis patients, collected on the first day of admission for antibiotic treatment, showed a high chemotactic index (19.4 ± 5.7, n = 8). Fractionation by gel filtration of bronchial secretions resulted in three chemotactic fractions. The first factor corresponded to interleukin-8, and the second activated neutrophils via the FMLP receptor. The third factor, which was of lower molecular weight, did not activate FMLP or leukotriene B4 receptors, and its nature is still under investigation. Treating patients with antibiotics reduced global chemotactic activity, mainly by reducing the activity due to stimulation of the FMLP recepto

Knowledge acquisition and effective socialization: the role of the psychological contract

Although studies reveal that acquiring knowledge about a new workplace during organizational socialization leads to better integration, the pathway through which this occurs is not well understood. Previous research has explored the psychological contract as an outcome of socialization. This study explores its role within the socialization process. A total of 161 organizational newcomers undertook surveys at months one and three of tenure, with data used to test a model within which four psychological contract dimensions mediate the relationship between knowledge acquisition and employee outcomes. At month one, organizational and employee promise strength mediated the relationship between knowledge and outcomes. At month three, organizational and employee promise fulfilment mediated this relationship. Findings confirm the role of the psychological contract in the socialization process and suggest that effective integration requires extensive knowledge provision and active employee knowledge acquisition. Practitioner points Acquisition of knowledge about a new work environment during the very early stages of tenure can positively affect newcomers’ attitudes and perceived employment relationships. Learning leads to mutual promises that are perceived to be stronger and more likely to be fulfilled, as well as reduced stress, greater commitment, and greater service quality behaviour. Employers should provide newcomers with information about their role, team, and organization, whilst newcomers should be encouraged to ask questions

Measurement of newcomer socialization: Construct validation of a multidimensional scale

Abstract A construct validation approach was taken to develop a primary measure of newcomer socialization that addresses shortcomings with a prior scal

Tweek, an Evolutionarily Conserved Protein, Is Required for Synaptic Vesicle Recycling

SummarySynaptic vesicle endocytosis is critical for maintaining synaptic communication during intense stimulation. Here we describe Tweek, a conserved protein that is required for synaptic vesicle recycling. tweek mutants show reduced FM1-43 uptake, cannot maintain release during intense stimulation, and harbor larger than normal synaptic vesicles, implicating it in vesicle recycling at the synapse. Interestingly, the levels of a fluorescent PI(4,5)P2 reporter are reduced at tweek mutant synapses, and the probe is aberrantly localized during stimulation. In addition, various endocytic adaptors known to bind PI(4,5)P2 are mislocalized and the defects in FM1-43 dye uptake and adaptor localization are partially suppressed by removing one copy of the phosphoinositide phosphatase synaptojanin, suggesting a role for Tweek in maintaining proper phosphoinositide levels at synapses. Our data implicate Tweek in regulating synaptic vesicle recycling via an action mediated at least in part by the regulation of PI(4,5)P2 levels or availability at the synapse

Huntingtin-interacting protein 14, a palmitoyl transferase required for exocytosis and targeting of CSP to synaptic vesicles

Posttranslational modification through palmitoylation regulates protein localization and function. In this study, we identify a role for the Drosophila melanogaster palmitoyl transferase Huntingtin-interacting protein 14 (HIP14) in neurotransmitter release. hip14 mutants show exocytic defects at low frequency stimulation and a nearly complete loss of synaptic transmission at higher temperature. Interestingly, two exocytic components known to be palmitoylated, cysteine string protein (CSP) and SNAP25, are severely mislocalized at hip14 mutant synapses. Complementary DNA rescue and localization experiments indicate that HIP14 is required solely in the nervous system and is essential for presynaptic function. Biochemical studies indicate that HIP14 palmitoylates CSP and that CSP is not palmitoylated in hip14 mutants. Furthermore, the hip14 exocytic defects can be suppressed by targeting CSP to synaptic vesicles using a chimeric protein approach. Our data indicate that HIP14 controls neurotransmitter release by regulating the trafficking of CSP to synapses