Hypothalamic-pituitary-adrenal axis response to stress in male DUI recidivists

Cortisol is a stress hormone mediated by the hypothalamic-pituitary-adrenal (HPA) axis and a psychobiological marker of genetic risk for alcoholism and other high-risk behavioural characteristics. In previous work with driving under the influence of alcohol (DUI) recidivists, we uncovered a significant inverse relationship between the frequency of past DUI convictions and salivary cortisol, whose strength surpassed those observed between DUI frequency and measures of alcohol abuse and other DUI-related characteristics. This finding emerged using a methodology not specifically contrived to test this relationship. The goals of this follow-up study were to (a) examine if a standardized stress-induction protocol would produce a significant inverse relationship between cortisol response and number of DUI offences; and (b) clarify whether HPA axis dysregulation could be linked to particular DUI-related behavioural correlates, such as alcohol use severity, sensation seeking, and antisocial features. Thirty male DUI recidivists were recruited as well as 11 male non-DUI drivers as a comparison group. Results indicated an inverse relationship between DUI frequency and cortisol response (r(39)=-0.36, p=0.021), as well as a lower cortisol response in DUI offenders than the comparison group (F(1,39)=5.71, p=0.022). Finally, for recidivists, hierarchical regression analyses indicated that experience seeking (R(2)=0.23, p=0.008), followed by number of cigarettes smoked daily ((Delta)R(2)=0.12, p=0.031), combined to explain 35% of the variance in cortisol (F(2,29)=7.26, p=0.003). These findings indicate that severe recidivism may have psychobiological underpinnings, and that HPA axis dysregulation appears to be a mechanism common to high-risk behaviours including DUI recidivism, sensation seeking, and cigarette smoking.     

Using Rasch scaled stage scores to validate orders of hierarchical complexity of balance beam task sequences

These studies examine the relationship between the analytic basis underlying the hierarchies produced by the Model of Hierarchical Complexity and the probabilistic Rasch scales that places both participants and problems along a single hierarchically ordered dimension. A Rasch analysis was performed on data from the balance-beam task series. This yielded scaled stage of performance for each of the items. The items formed a series of clusters along this same dimension, according to their order of hierarchical complexity. We sought to ascertain whether there was a significant relationship between the order of hierarchical complexity (a task property variable) of the tasks and the corresponding Rasch scaled difficulty of those same items (a performance variable). It was found that The Model of Hierarchical Complexity was highly accurate in predicting the Rasch Stage scores of the performed tasks, therefore providing an analytic and developmental basis for the Rasch scaled stages.     

Increase in the vascular residence time of propranolol-loaded nanoparticles coated with heparin

Propranolol-HCI incorporated nanoparticles prepared with a blend of a polyester and a polycationic polymer and coated or not with a low molecular weight heparin by electrostatic interactions were prepared by emulsification followed by solvent evaporation. The mean diameter was 388 and 357 nm for coated and uncoated nanoparticles, respectively, and the entrapment efficiency ranged from 20 to 32%. Coated nanoparticles were negatively-charged, whereas uncoated nanoparticles displayed a positive zeta potential (+30 mV). After intravenous administration to rabbits of propranolol-HCI solution and propranolol-loaded nanoparticles coated or not with heparin, pharmacokinetic data revealed that coated nanoparticles exhibited a prolonged blood residence time. It can be concluded that the hydrophilic layer of heparin at the surface of nanoparticles conferred stealth properties which probably reduce the phagocytosis process and avoid immediate uptake by the mononuclear phagocytic system.     

Functional properties of thermoformed wheat gluten/montmorillonite materials with respect to formulation and processing conditions

Wheat gluten (WG)/montmorillonite (MMT) films were prepared by a thermomechanical process consisting of first mixing the components in a two‐blade, counter‐rotating device and second thermoforming the obtained dough. A significant loss in protein solubility due to the formation and rearrangement of disulfide bonds was observed upon mixing and thermoforming. In the range of studied glycerol contents (25–42.8 wt %), it was shown that glycerol had no significant effect on the mechanical properties or water sensitivity of WG‐based films. Increasing the thermoforming temperature from 60 to 120°C led to considerable improvements of the mechanical properties (increases in both the stress and strain at break) and a significant reduction of the water sensitivity. The introduction of MMT (up to 5 wt %) allowed the achievement of mechanical properties that were not possible by just the variation of the glycerol content and the processing temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Aphid and Plant Volatiles Induce Oviposition in an Aphidophagous Hoverfly

Episyrphus balteatus DeGeer (Diptera, Syrphidae) is an abundant and efficient aphid-specific predator. We tested the electroantennographic (EAG) response of this syrphid fly to the common aphid alarm pheromone, (E)-β-farnesene (EβF), and to several plant volatiles, including terpenoids (mono- and sesquiterpenes) and green leaf volatiles (C6 and C9 alcohols and aldehydes). Monoterpenes evoked significant EAG responses, whereas sesquiterpenes were inactive, except for the aphid alarm pheromone (EβF). The most pronounced antennal responses were elicited by six and nine carbon green leaf alcohols and aldehydes [i.e., (Z)-3-hexenol, (E)-2-hexenol, (E)-2-hexenal, and hexanal]. To investigate the behavioral activity of some of these EAG-active compounds, E. balteatus females were exposed to R-(+)-limonene (monoterpene), (Z)-3-hexenol (green leaf alcohol), and EβF (sesquiterpene, common aphid alarm pheromone). A single E. balteatus gravid female was exposed for 10 min to an aphid-free Vicia faba plant that was co-located with a semiochemical dispenser. Without additional semiochemical, hoverfly females were not attracted to this plant, and no oviposition was observed. The monoterpene R-(+)-limonene did not affect the females’ foraging behavior, whereas (Z)-3-hexenol and EβF increased the time of flight and acceptance of the host plant. Moreover, these two chemicals induced oviposition on aphid-free plants, suggesting that selection of the oviposition site by predatory hoverflies relies on the perception of a volatile blend composed of prey pheromone and typical plant green leaf volatiles.     

Molecular dynamics simulations of Na+/Cl(-)-dependent neurotransmitter transporters in a membrane-aqueous system

We have performed molecular dynamics simulations of a homology model of the human serotonin transporter (hSERT) in a membrane environment and in complex with either the natural substrate 5-HT or the selective serotonin reuptake inhibitor escitalopram. We have also included a transporter homologue, the Aquifex aeolicus leucine transporter (LeuT), in our study to evaluate the applicability of a simple and computationally attractive membrane system. Fluctuations in LeuT extracted from simulations are in good agreement with crystallographic B factors. Furthermore, key interactions identified in the X-ray structure of LeuT are maintained throughout the simulations indicating that our simple membrane system is suitable for studying the transmembrane protein hSERT in complex with 5-HT or escitalopram. For these transporter complexes, only relatively small fluctuations are observed in the ligand-binding cleft. Specific interactions responsible for ligand recognition, are identified in the hSERT-5HT and hSERT-escitalopram complexes. Our findings are in good agreement with predictions from mutagenesis studies.     

Particle size coarsening induced by valve silicone in a metered dose inhaler

The objective of this study was to evaluate the effect of valve silicone on the delivered particle size distribution of a suspension metered dose inhaler (MDI). Valves were manufactured with distinct levels of silicone, which could be differentiated with Fourier transform infrared spectroscopy (FT-IR). The amount of silicone in the valve was proportional to the amount of silicone that entered the formulation and the subsequent decrease in fine particle fraction (FPF) of the active pharmaceutical ingredient (API) measured by Andersen cascade impaction. The effect of silicone content was not linear as even small amounts of silicone made a significant contribution to particle size coarsening. This coarsening was also a function of storage time and temperature. Accelerated stability conditions greatly increased coarsening kinetics as 1 month at 40°C and 75% RH induced significantly more coarsening than 12 months at room temperature. Field emission scanning electron micrograph images suggest that the primary mechanism of particle size change may be aggregation as particle clusters were seen. This study indicates that silicone can be a critical process parameter for particle size distribution of a suspension MDI product. Thus, the amount of silicone in the valves needs to be minimized and controlled.