Pseudomonas aeruginosa elastase disables proteinase-activated receptor 2 in respiratory epithelial cells

Pseudomonas aeruginosa, a major lung pathogen in cystic fibrosis (CF) patients, secretes an elastolytic metalloproteinase (EPa) contributing to bacterial pathogenicity. Proteinase-activated receptor 2 (PAR2), implicated in the pulmonary innate defense, is activated by the cleavage of its extracellular N-terminal domain, unmasking a new N-terminal sequence starting with SLIGKV, which binds intramolecularly and activates PAR2. We show that EPa cleaves the N-terminal domain of PAR2 from the cell surface without triggering receptor endocytosis as trypsin does. As evaluated by measurements of cytosolic calcium as well as prostaglandin E(2) and interleukin-8 production, this cleavage does not activate PAR2, but rather disarms the receptor for subsequent activation by trypsin, but not by the synthetic receptor-activating peptide, SLIGKV-NH(2). Proteolysis by EPa of synthetic peptides representing the N-terminal cleavage/activation sequences of either human or rat PAR2 indicates that cleavages resulting from EPa activity would not produce receptor-activating tethered ligands, but would disarm PAR2 in regard to any further activating proteolysis by activating proteinases. Our data indicate that a pathogen-derived proteinase like EPa can potentially silence the function of PAR2 in the respiratory tract, thereby altering the host innate defense mechanisms and respiratory functions, and thus contributing to pathogenesis in the setting of a disease like CF.     

Evaluation of commercial assay detecting specific immunoglobulin g in oral fluid for determining measles immunity in vaccinees

A commercial assay for detection of measles immunoglobulin G (IgG) in oral fluid was evaluated in a highly vaccinated cohort using serum IgG as gold standard. In contrast to previous studies from cohorts protected by natural immunity, antibody prevalence was significantly underestimated (-7.4%; confidence interval: -1.5 to -13.2%; P = 0.01) due to a reduced sensitivity when antibody levels were low.     

In vivo determination of optical properties of normal and tumor tissue with white light reflectance and an empirical light transport model during endoscopy

Determination of tissue optical properties is fundamental for application of light in either therapeutical or diagnostics procedures. In the present work we implemented a spatially resolved steady-state diffuse reflectance method where only two fibers (one source and one detector) spaced 2.5 mm apart are used for the determination of the optical properties. The method relies on the spectral characteristics of the tissue chromophores (water, dry tissue, and blood) and the assumption of a simple wavelength dependent expression for the determination of the reduced scattering coefficient. Because of the probe dimensions the method is suited for endoscopic measurements. The method was validated against more traditional models, such as the diffusion theory combined with adding doubling for in vitro measurements of bovine muscle. Mean and standard deviation of the absorption coefficient and the reduced scattering coefficient at 630 nm for normal mucosa were 0.87+/-0.22 cm(-1) and 7.8+/-2.3 cm(-1), respectively. Cancerous mucosa had values 1.87+/-1.10 cm(-1) and 8.4+/-2.3 cm(-1), respectively. These values are similar to data presented by other authors. Blood perfusion was the main variable accounting for differences in the absorption coefficient between the studied tissues.     

Functional mu opioid receptors are expressed in cholinergic interneurons of the rat dorsal striatum: territorial specificity and diurnal variation

Striatal cholinergic interneurons play a crucial role in the control of movement as well as in motivational and learning aspects of behaviour. Neuropeptides regulate striatal cholinergic transmission and particularly activation of mu opioid receptor (MOR) inhibits acetylcholine (ACh) release in the dorsal striatum. In the present study we investigated whether this cholinergic transmission could be modulated by an enkephalin/MOR direct process. We show that mRNA and protein of MORs are expressed by cholinergic interneurons in the limbic/prefrontal territory but not by those in the sensorimotor territory of the dorsal striatum. These MORs are functional because potassium-evoked release of ACh from striatal synaptosomes was dose-dependently reduced by a selective MOR agonist, this effect being suppressed by a MOR antagonist. The MOR regulation of cholinergic interneurons presented a diurnal variation. (i) The percentage of cholinergic interneurons containing MORs that was 32% at the beginning of the light period (morning) increased to 80% in the afternoon. (ii) The MOR-mediated inhibition of synaptosomal ACh release was higher in the afternoon than in the morning. (iii) While preproenkephalin mRNA levels remained stable, enkephalin tissue content was the lowest (-32%) in the afternoon when the spontaneous (+35%) and the N-methyl-d-aspartate-evoked (+140%) releases of enkephalin (from microsuperfused slices) were the highest. Therefore, by acting on MORs present on cholinergic interneurons, endogenously released enkephalin reduces ACh release. This direct enkephalin/MOR regulation of cholinergic transmission that operates only in the limbic/prefrontal territory of the dorsal striatum might contribute to information processing in fronto-cortico-basal ganglia circuits.     

The metabolic syndrome and type 2 diabetes: epidemiological figures and country specificities

Over the last 20 years, the prevalence of the metabolic syndrome has steadily increased in all populations worldwide, changing slowly the phenotype of the human race and potentially our concept of physiological normality. Our affluent phenotype reflects progressive adaptation to the external environment, which in turn changes the standards of the metabolic variables such as body weight, blood pressure, lipid values and glucose homeostasis. The human survivors of the difficult times of the hunter-gatherer period have probably benefited from genes which have allowed for more efficient food utilization, fat deposition and weight gain, a concept referred to as the 'thrifty gene' hypothesis. This genetic background has now become detrimental in our society of high energy consumption, little physical activity and lifestyles that favour stress and anxiety. These genetic and environmental interactions explain the explosion in the prevalence of the metabolic syndrome and diabetes. If future estimates for the number of patients with diabetes and impaired glucose tolerance are valid, this will have a major and adverse impact on the number of stroke patients globally.     

Genetic lipoprotein disorders and coronary atherosclerosis

Familial lipoprotein disorders are seen frequently in subjects with premature coronary artery disease. The genetic basis for several dyslipoproteinemias has been elucidated in the past two decades. The majority of lipoprotein disorders result from a combination of polygenic predisposition and poor lifestyle habits, including physical inactivity, increased visceral adipose tissue, increased caloric intake, and cigarette smoking. Monogenic disorders are seen in approximately 5% of premature coronary artery disease cases, and this prevalence is higher in populations with the Founder effect. Unraveling the genetic basis of many lipoprotein disorders has allowed fundamental discoveries in molecular cellular physiology and has paved the way for novel therapeutic approaches.     

Analysis of genetic polymorphisms in acetylcholinesterase as reflected in different populations

Acetylcholinesterase (AChE) plays a crucial physiological role in termination of impulse transmission at cholinergic synapses through rapid hydrolysis of acetylcholine. In addition, it was implicated in amyloid plaque formation, a hallmark of Alzheimer's disease (AD), and most of the drugs used in AD treatment are AChE inhibitors. Thus ACHE is an obvious candidate gene for pharmacogenetic study of AD treatment. However, AChE is a highly conserved molecule, and only a few naturally occurring genetic polymorphisms have been reported in the human gene. The goals of this study were to make a systematic effort to identify natural single nucleotide polymorphisms (SNPs) in the human ACHE gene, and to reveal their population specific architecture. To this end, the genomic coding sequences for AChE of 96 unrelated control individuals from three distinct ethnic groups, African Americans, Ashkenazi Jews and Israeli Arabs, were analyzed. Thirteen ACHE SNPs were identified, ten of which are newly described, and five of which should produce amino-acid substitutions (Arg34Gln, Gly57Arg, Glu344Gly, His353Asn and Pro592Arg). Population frequencies of 11 of the 13 SNPs were established in four different populations, African Americans, Ashkenazi Jews, Sephardic Jews and Israeli Arabs; 17 haplotypes and 5 ethno-specific alleles were identified, and a cladogram of ACHE haplotypes was constructed. Among the SNPs resulting in an amino-acid substitution, three are within the mature protein, mapping on its external surface; they are thus unlikely to affect its catalytic properties, yet could have antigenic consequences or affect putative protein-protein interactions. Furthermore, the newly identified SNPs open the door to a study of the possible association of AChE with deleterious phenotypes - such as adverse drug responses to AChE inhibitors employed in treatment of AD patients and hypersensitivity to pesticides.     

Sleep of preterm neonates under developmental care or regular environmental conditions

Sleep is the main behavioral state of the premature infant. In adult intensive care units, sleep deprivation has been reported as one of the major stressors. Developmental care (DC) aims to decrease stressful events in neonatal intensive care unit and support well-being. AIM: To assess whether DC is accompanied by changes in sleep in preterm neonates. METHODS: A prospective cross-over study included 33 preterm neonates [mean (S.D.): gestational age: 29.3 (1.8) weeks; birth weight: 1245 (336) g]. Polysomnography was performed in two randomly ordered 3-h periods with and without DC. A blinded electrophysiologist analyzed sleep. The total sleep time (TST) was the primary outcome, duration of active (AS), quiet (QS) and indeterminate sleep, and latency before sleep were the secondary outcomes. Non-parametric Wilcoxon tests and ANOVA were used. RESULTS: In DC condition vs. control: TST increased [in minutes, mean (S.E.M.): 156.2 (2.9) vs. 139.2 (4.6), p=0.002], with increase in AS [86.6 (3.7) vs. 77.0 (4.2), p=0.024] and in QS [47.1 (4.1) vs. 36.9 (4.2), p=0.015], and sleeping latency decreased (2.1 (0.7) vs. 10.5 (2.0), p=0.0005]. CONCLUSION: DC promoted sleep in our study. The impact of DC on the neuro-behavioral outcome needs futures studies.     

Factors associated with fragmented sleep at night across early childhood

OBJECTIVE: To identify the factors most strongly associated with sleeping less than 6 consecutive hours at night for children aged 5, 17, and 29 months. DESIGN, SETTING, AND PARTICIPANTS: A randomized survey design used a representative sample of infants born in 1997-1998 in the Canadian province of Quebec. Data were collected by questionnaires and interviews. Interviews were scheduled at home with the mothers. The number of consecutive hours slept at night by 1741 children aged 5, 17, and 29 months was assessed from parental reports. Factors associated with fragmented sleep were investigated for each age in a cross-sectional design. RESULTS: At 5 months of age, 23.5% of children did not sleep 6 consecutive hours. Of the children who did not sleep 6 consecutive hours at night at 5 months or 17 months of age, 32.9% were still not sleeping 6 consecutive hours at night at 29 months of age. The factor most strongly associated with not sleeping at least 6 consecutive hours per night at 5 months of age was feeding the child after an awakening. Parental presence until sleep onset was the factor most strongly associated with not sleeping at least 6 consecutive hours per night at 17 months and 29 months of age. CONCLUSIONS: Sleep consolidation evolves rapidly in early childhood. Parental behaviors at bedtime and in response to a nocturnal awakening are highly associated with the child's sleep consolidation. The effects are probably bidirectional and probably create a long-term problem. Early interventions could possibly break the cycle.