The major cockroach allergen Bla g 4 binds tyramine and octopamine

Bla g 4 is a male cockroach specific protein and is one of the major allergens produced by Blattella germanica (German cockroach). This protein belongs to the lipocalin family that comprises a set of proteins that characteristically bind small hydrophobic molecules and play a role in a number of processes such as: retinoid and pheromone transport, prostaglandin synthesis and mammalian immune response. Using NMR and isothermal titration calorimetry we demonstrated that Bla g 4 binds tyramine and octopamine in solution. In addition, crystal structure analysis of the complex revealed details of tyramine binding. As tyramine and octopamine play important roles in invertebrates, and are counterparts to vertebrate adrenergic transmitters, we speculate that these molecules are physiological ligands for Bla g 4. The nature of binding these ligands to Bla g 4 sheds light on the possible biological function of the protein. In addition, we performed a large-scale analysis of Bla g 4 and Per a 4 (an allergen from American cockroach) homologs to get insights into the function of these proteins. This analysis together with a structural comparison of Blag 4 and Per a 4 suggests that these proteins may play different roles and most likely bind different ligands.     

Fenfluramine suppresses snack intake among carbohydrate cravers but not among noncarbohydrate cravers

Two groups of obese individuals who consume excessive calories primarily as snack foods have been distinguished: carbohydrate cravers and noncarbohydrate cravers. Both groups consume about 800 calories from snacks (860 kcal vs 879 kcal) and about 2000 calories from meals (1906 kcal vs 2080 kcal) daily. The carbohydrate-cravers consume almost all of their snacks as carbohydrate-rich foods (7 ± 0.4 CHO snacks/day vs 0.9 ± 0.12 protein snacks/day) whereas the noncarbohydrate cravers consume approximately equal numbers of protein and carbohydrate snacks (4.5 ± 0.6 carbohydrate snacks/day vs 3.5 ± 0.5 protein snacks/day). D-fenfluramine significantly reduced the intakes of calories (range 24–44%) and carbohydrates (range 28–41%) from snacks among the carbohydrate cravers over a three month treatment period. The drug did not affect snack intake by the noncarbohydrate cravers until the third month of treatment when the consumption of both types of snacks decreased significantly. D-fenfluramine decreased mealtime carbohydrate intake among the carbohydrate cravers throughout the treatment period (range 16–23%); mealtime protein intake declined comparably (range 14–18%) during the first and third treatment months. The drug had no effect on mealtime carbohydrate nor protein intake by noncarbohydrate cravers.     

A longitudinal analysis of the experiences of nursing staff on an inpatient eating disorders unit

The present study assessed whether nurses working in an inpatient eating disorders unit experience any increased risk as a result of treating patients with anorexia nervosa, bulimia, and variants of these two disorders. There were 23 newly hired or just transferred primary care nurses (12 in an eating disorders program and 11 in other service areas) who were weighed monthly and completed the following instruments either monthly or semimonthly for 13 months: Beck Depression Inventory, Eating Attitudes Test, Impressions of Patient Population Survey, job Satisfaction Inventory, and Attitudes toward Patient Questionaire. Results indicated that nurses in the eating disorders program had less distorted eating attitudes, less positive impressions of their patients, and greater job satisfaction than their counterparts from other service areas. Nurses from both groups had progressively less positive impressions of their patients and lower job satisfaction over the course of the study. These findings suggest that when certain team-building experiences (e.g., inservice training, interdisciplinary team meetings) are incorporated into an eating disorders unit, nurses face no special risks in the areas of mood and eating disturbance.     

Transverse stiffness: a method for estimation of myocardial wall stress

Determination of regional ventricular wall stress would allow quantification of both regional contractile state and its interplay with global function. Current methods for quantifying regional stress include mathematical modelling and measurements with strain gauges. Both methods are difficult to validate. We hypothesized that transverse stiffness (i.e., the ratio of indentation stress to strain as the ventricular wall is indented in the direction perpendicular to the wall) would be proportional to the stresses in the plane of the wall and could be used to estimate the latter. To test this hypothesis, 6 arterially perfused canine ventricular septa were mounted in an apparatus that could exert biaxial load in the plane of the wall. A servo system maintained the central third of the septa isometric during active contractions while the septa were paced at 30-60 pulses/min. In the center of the isometric region, a probe of 7 mm diameter indented the septa while the transverse indentation stress and strain were measured. For values of peak systolic in-plane stress from 0.56 to 2.6 g/mm2, the transverse stiffness varied from 1.2 to 11.7 g/mm2 and was linearly related to the in-plane wall stress in each septum (p less than 0.001, ANOVA). After cardioplegia, the transverse stiffness also correlated with passively applied wall stress for each dog (p less than 0.001). The slopes of the individual relations between transverse stiffness and wall stress from active contractions were similar to those from passively applied stress (mean +/- SEM; 1.82 +/- 0.36 versus 1.45 +/- 0.31, NS).(ABSTRACT TRUNCATED AT 250 WORDS)     

Regulation of glutamate transporters in astrocytes: Evidence for a relationship between transporter expression and astrocytic phenotype

The astrocytic glutamate transporters, EAAT1 and EAAT2, remove released L-glutamate from the synaptic milieu thereby maintaining normal excitatory transmission. EAAT dysfunction during the excitotoxicity and oxidative stress of neurological insults may involve homoeostatic mechanisms associated with astrocytic function. We investigated aspects of EAAT function and expression in concert with astrocytic phenotype in primary cultures of cortical astrocytes and mixed cells of the spinal cord. In spinal cord mixed cultures, hydrogen peroxide (300 microM) reduced both EAAT activity and cellular viability to half of their basal values at 24 h post-treatment, but at 2 h EAAT activity was unaltered, while cellular viability was significantly decreased, suggestive of a mechanism for the maintenance of EAAT activity. Cytochemistry for MAP2, GFAP and propidium iodide revealed that neurons and astrocytes were damaged in a time-dependent manner. A change in astrocyte morphology was observed, with astrocyte cell bodies becoming larger and processes becoming more stellate and often shorter in length. EAAT1 immunoreactivity was reduced at 24 h post-treatment and a re-distribution of the protein was noted after 2 h treatment. In pure astrocytes, lipopolysaccharide (1 microg/ml, 3 d) increased [3H]D-aspartate uptake by 90%, as well EAAT1 immunoreactivity and astrocyte stellation, as shown by immunofluorescent labelling for GFAP. In both culture systems, prominent changes were noted in EAAT function and localization in conjunction with altered astrocytic phenotype. Our findings are indicative of a relationship between astrocytic phenotype and the level of EAAT activity that may be a vital component of astrocytic homeostatic responses in brain injury.