B-cell depletion reactivates B lymphopoiesis in the BM and rejuvenates the B lineage in aging

Aging is associated with a decline in B-lymphopoiesis in the bone marrow and accumulation of long-lived B cells in the periphery. These changes decrease the body's ability to mount protective antibody responses. We show here that age-related changes in the B lineage are mediated by the accumulating long-lived B cells. Thus, depletion of B cells in old mice was followed by expansion of multipotent primitive progenitors and common lymphoid progenitors, a revival of B-lymphopoiesis in the bone marrow, and generation of a rejuvenated peripheral compartment that enhanced the animal's immune responsiveness to antigenic stimulation. Collectively, our results suggest that immunosenescence in the B-lineage is not irreversible and that depletion of the long-lived B cells in old mice rejuvenates the B-lineage and enhances immune competence.     

Flow cytometry for the diagnosis of autoimmune thrombocytopenia

Autoimmune thrombocytopenia is a disorder characterized by antibody-mediated accelerated platelet destruction. Despite its clinical importance, the diagnosis of autoimmune thrombocytopenia is one of exclusion, thus inevitably associated with potential difficulties. Current clinically applicable methods used to determine antigen-specific antibodies, primarily directed to GPIIb/IIIa (CD41a) and GPIb (CD42b), include the monoclonal antibody-specific immobilization of platelet antigen (MAIPA) assay and the radioactive immunobead assay. Neither of these assays is commonly used by clinical laboratories, however, because of methodologic and practical limitations. As a result, diagnoses are generally based on clinical impression despite patient presentations that are sometimes complex. To overcome some of these difficulties, flow cytometric techniques have been developed, employing standard methods and equipment suitable for testing a single sample or multiple samples, as may occur in cases of autoimmune thrombocytopenia. The availability of a feasible technique such as flow cytometry, with improved sensitivity and specificity, should facilitate the routine use of a diagnostic method in the evaluation of thrombo-cytopenic patients suspected of having an autoimmune disorder and permit follow-up to determine immune remission.     

Agreement between laboratory results and on-site pathology testing using Bayer DCA2000+ and Cholestech LDX point-of-care methods in remote Australian Aboriginal communities

BACKGROUND: Indigenous Australians experience high risk of diabetes and cardiovascular disease. On-site pathology data can help identify those at risk. We sought to evaluate point-of-care (POC) analysers in remote Australian communities. METHODS: Results obtained from population screening (n=76-118) on the DCA2000+ and Cholestech LDX analysers were compared to laboratory measures. Results were compared using parametric and non-parametric statistical analyses, including the use of conventional cut-off values for pathology markers. RESULTS: Agreements (95% CI) between the two methods for categorising results according to the selected cut-off values ranged from 88% (77-94%) for HDL-C to 99% (92-100%) for glucose, and Kappa coefficients ranged from 0.668 for total cholesterol to 0.945 for glucose. Differences in median values were not clinically meaningful but were statistically significant (P<0.05) for urinary albumin (18.8 [inter-quartile range: 7.5-41.7] vs. 18.0 [5.5-43.2] mg/L), creatinine (12.1 [7.9-17.1] vs. 12.4 [8.1-17.0] mmol/L) and albumin:creatinine ratio (ACR; 1.66 [0.70-3.53] vs. 1.27 [0.46-3.03] mg/mmol), HDL cholesterol (HDL-C; 1.05 [0.95-1.25] vs. 1.00 [0.81-1.20] mmol/L), triglycerides (1.65 [1.12-2.19] vs. 1.49 [1.07-2.36] mmol/L) and glucose (5.2 [4.5-6.0] vs. 5.2 [4.7-5.8] mmol/L), respectively, for POC and laboratory methods. Median HbA1c (5.6% [5.3-6.0%] vs. 5.5% [5.3-6.1%]) and total cholesterol (4.4 [3.8-5.0] vs. 4.4 [3.8-5.1] mmol/L) did not differ significantly. Bland-Altman analyses showed statistically significant (but not clinically meaningful) variation in the measurement difference across analyte concentration for all measures except ACR and total cholesterol. CONCLUSION: POC instruments provided a reliable alternative to conventional laboratory methods for screening for chronic disease risk factors in locations remote from urban centres.     

Leanness and type 2 diabetes in a population of indigenous Australians

OBJECTIVE: To determine the prevalence of type 2 diabetes and its risk factors in a population of indigenous Australians. RESEARCH DESIGN AND METHODS: A cross-sectional study of 332 indigenous community residents aged 15 years and over with fasting blood samples and anthropometric measurements. RESULTS: Almost half of the study population (47.3%) was extremely lean (BMI<22 kg/m(2)). Leanness was particularly pronounced in the youngest age group (15<20 years), 78% of which had a BMI<22 kg/m(2). The prevalence of diabetes was 12%. It was highest in those 45-54 years and declined in older aged people. No cases of diabetes were detected in those aged less than 30 years. Diabetes prevalence was strongly linked to BMI and age (age-adjusted odds ratio=24.1, 95% CI 6.0-96.5, p<0.001) for BMI>or=25 kg/m(2) versus BMI<22 kg/m(2). Those with the lowest diabetes risk profile are lean (BMI<22 kg/m(2)) and/or young (age 15-34 years). CONCLUSIONS: These results highlight that strategies to prevent or delay the onset of diabetes should focus on the maintenance of leanness from adolescence and throughout adult life whilst young people are still in the process of forming lifelong habits.     

Hand immersion in cold water alleviating physiological strain and increasing tolerance to uncompensable heat stress

The current study examines the use of hand immersion in cold water to alleviate physiological strain caused by exercising in a hot climate while wearing NBC protective garments. Seventeen heat acclimated subjects wearing a semi-permeable NBC protective garment and a light bulletproof vest were exposed to a 125 min exercise-heat stress (35 degrees C, 50% RH; 5 km/h, 5% incline). The heat stress exposure routine included 5 min rest in the chamber followed by two 50:10 min work-rest cycles. During the control trial (CO), there was no intervention, whilst in the intervention condition the subjects immersed their hands and forearms in a 10 degrees C water bath (HI). The results demonstrated that hand immersion in cold water significantly reduced physiological strain. In the CO exposure during the first and second resting periods, the average rectal temperature (T (re)) practically did not decrease. With hand immersion, the mean (SD) T (re) decreased by 0.45 (0.05 degrees C) and 0.48 degrees C (0.06 degrees C) during the first and second rest periods respectively (P < 0.005). Significant decreases in skin temperature, sweat rate, heart rate, and heat storage was also noted in the HI vs. the CO trials. Tolerance time in the HI exposure were longer than in the CO exposure (only 12 subjects in the CO trial endured the entire heat exposure session, as opposed to all 17 subjects in the HI group). It is concluded that hand immersion in cold water for 10 min is an effective method for decreasing the physiological strain caused by exercising under heat stress while wearing NBC protective garments. The method is convenient, simple, and allows longer working periods in hot or contaminated areas with shorter resting periods.     

Incentive motivation is associated with striatal dopamine asymmetry

Dopamine plays an important role in modulating incentive motivation, expressed behaviorally as approach behavior. EEG studies report association between approach behavior and asymmetric pattern of activation in anterior cortical regions (as measured by the inverse of EEG alpha power). Therefore, individual differences in incentive motivation may reflect asymmetries in dopaminergic systems. We examined this hypothesis by studying the relationship between self-reported degree of incentive motivation, and asymmetry of D2 receptor availability in healthy volunteers. Nineteen healthy participants were studied with positron emission tomography (PET) and [11C]raclopride to assess the availability of dopamine D2 receptors in left and right striatum. Incentive motivation was assessed by the Achievement scale of the Multidimensional Personality Questionnaire. The Achievement score was negatively correlated with the Asymmetry Index ([R-L]/[R+L]) of D2 receptor availability (r=-.721, p=.001), suggesting that greater positive incentive motivation is associated with higher receptor availability in the left relative to the right hemisphere.     

Attention biases,anxiety, and development: toward or away from threats or rewards?

Research on attention provides a promising framework for studying anxiety pathophysiology and treatment. The study of attention biases appears particularly pertinent to developmental research, as attention affects learning and has down-stream effects on behavior. This review summarizes recent findings about attention orienting in anxiety, drawing on findings in recent developmental psychopathology and affective neuroscience research. These findings generate specific insights about both development and therapeutics. The review goes beyond a traditional focus on biased processing of threats and considers biased processing of rewards. Building on this work, we then turn to the treatment of pediatric anxiety, where manipulation of attention to threat and/or reward may serve a therapeutic role as a component of Attention Bias Modification Therapy.     

Procainamide, but not N-acetylprocainamide, induces protein free radical formation on myeloperoxidase: a potential mechanism of agranulocytosis

Procainamide (PA) is a drug that is used to treat tachycardia in postoperative patients or for long-term maintenance of cardiac arrythmias. Unfortunately, its use has also been associated with agranulocytosis. Here, we have investigated the metabolism of PA by myeloperoxidase (MPO) and the formation of an MPO protein free radical. We hypothesized that PA oxidation by MPO/H 2O 2 would produce a PA cation radical that, in the absence of a biochemical reductant, would lead to the free radical oxidation of MPO. We utilized a novel anti-DMPO antibody to detect DMPO (5,5-dimethyl-1-pyrroline N-oxide) covalently bound to protein, which forms by the reaction of DMPO with a protein free radical. We found that PA metabolism by MPO/H 2O 2 induced the formation of DMPO-MPO, which was inhibited by MPO inhibitors and ascorbate. N-acetyl-PA did not cause DMPO-MPO formation, indicating that the unsubstituted aromatic amine was more oxidizable. PA had a lower calculated ionization potential than N-acetyl-PA. The DMPO adducts of MPO metabolism, as analyzed by electron spin resonance spectroscopy, included a nitrogen-centered radical and a phenyl radical derived from PA, either of which may be involved in the free radical formation on MPO. Furthermore, we also found protein-DMPO adducts in MPO-containing, intact human promyelocytic leukemia cells (HL-60). MPO was affinity-purified from HL-60 cells treated with PA/H 2O 2 and was found to contain DMPO using the anti-DMPO antibody. Mass spectrometry analysis confirmed the identity of the protein as human MPO. These findings were also supported by the detection of protein free radicals with electron spin resonance in the cellular cytosolic lysate. The formation of an MPO protein free radical is believed to be mediated by free radical metabolites of PA, which we characterized by spin trapping. We propose that drug-induced free radical formation on MPO may play a role in the origin of agranulocytosis.