Heart muscle excitation-contraction (E-C) coupling is governed by Ca 2؉ release units (CRUs) whereby Ca 2؉ influx via L-type Ca 2؉ channels (Cav1.2) triggers Ca 2؉ release from juxtaposed Ca 2؉ release channels (RyR2) located in junctional sarcoplasmic reticulum (jSR). Although studies suggest that the jSR protein triadin anchors cardiac calsequestrin (Casq2) to RyR2, its contribution to E-C coupling remains unclear. Here, we identify the role of triadin using mice with ablation of the Trdn gene (Trdn ؊/؊ ). The structure and protein composition of the cardiac CRU is significantly altered in Trdn ؊/؊ hearts. jSR proteins (RyR2, Casq2, junctin, and junctophilin 1 and 2) are significantly reduced in Trdn ؊/؊ hearts, whereas Cav1.2 and SERCA2a remain unchanged. Electron microscopy shows fragmentation and an overall 50% reduction in the contacts between jSR and T-tubules. Immunolabeling experiments show reduced colocalization of Cav1.2 with RyR2 and substantial Casq2 labeling outside of the jSR in Trdn ؊/؊ myocytes. CRU function is impaired in Trdn ؊/؊ myocytes, with reduced SR Ca 2؉ release and impaired negative feedback of SR Ca 2؉ release on Cav1.2 Ca 2؉ currents (ICa). Uninhibited Ca 2؉ influx via ICa likely contributes to Ca 2؉ overload and results in spontaneous SR Ca 2؉ releases upon ␤-adrenergic receptor stimulation with isoproterenol in Trdn ؊/؊ myocytes, and ventricular arrhythmias in Trdn ؊/؊ mice. We conclude that triadin is critically important for maintaining the structural and functional integrity of the cardiac CRU; triadin loss and the resulting alterations in CRU structure and protein composition impairs E-C coupling and renders hearts susceptible to ventricular arrhythmias.cardiac muscle ͉ sarcoplasmic reticulum ͉ calsequestrin ͉ Cav1.2 ͉ RyR2

Chemokine receptors on T cells are frequently categorized as functioning either in immune system homeostasis within lymphoid organs, or in peripheral inflammation. CXCR3 is in the latter category and is reported to be expressed selectively on Th1 cells. We found that CXCR3 was expressed in vivo on newly activated tonsillar CD4+ T cells. Using CD4+ T cells from cord blood, we found that CXCR3 was induced by cellular activation in vitro independently of the cytokine milieu, although on resting cells, expression was maintained preferentially on those that had been activated in type 1 conditions. In inflamed tonsils, CXCR3+CD4+ T cells were localized around and within germinal centers. The inference that CXCR3 has a role in germinal center reactions was supported by the finding that the CXCR3 ligand CXC chemokine ligand 9 was expressed in a pattern demarcating a subset of germinal centers both in tonsil and in lymph nodes from an HIV-infected individual. We next investigated the role of CXCR3 on peripheral effector/memory CD4+ T cells by comparing its pattern of expression with that of CCR5, another Th1-cell associated chemokine receptor. Analysis of cells directly from peripheral blood and after activation in vitro suggested that CXCR3 expression preceded that of CCR5, supporting a model of sequential induction of chemokine receptors during CD4+ T cell differentiation. Taken together, our data show that CXCR3 can be expressed at all stages of CD4+ T cell activation and differentiation, bridging central function in lymphoid organs and effector function in peripheral tissues.

Human heart failure is characterized by contractile dysfunction, electrophysiological remodelling and sudden death (Tomaselli et al. 1994). At the cellular level, the prolongation of the ventricular action potential, most probably induced by suppression of the transient outward K¤ current (Ito) and the inward rectifying K¤ current (IK1) and slower inactivation of the calcium current (ICa), as well as the enhancement of the Na¤-Ca¥ exchanger are consistently reported for human and animal models of heart failure (Studer et al. 1994;Hatem et al. 1994;Momtaz et al. 1996;Kaab et al. 1996;Thuringer et al. 1996;Hasenfuss et al. 1997;Nabauer & Kaab, 1998;O'Rourke et al. 1999). It has Journal of Physiology (2000), 525.2, pp. 483-498 483 Remodelling of ionic currents in hypertrophied and failing hearts of transgenic mice overexpressing calsequestrin 1. Overexpression of cardiac calsequestrin (CSQ) impairs Ca¥ signalling in murine myocytes, leading to marked cardiac hypertrophy. Here we report on contractile, histological and electrophysiological changes accompanying the development of cardiac hypertrophy and failure in CSQ-overexpressing mice. 2. CSQ mice developed contractile dysfunction after 60 days of age, with only 40% survival at 6 months. Four-to 6-month-old CSQ mice revealed biventricular dilatation, cardiomyocyte hypertrophy, patchy interstitial fibrosis and tissue calcifications. 3. Cardiac hypertrophy of CSQ mice was accompanied by progressive P-R and Q-T interval prolongation, conduction blocks, 2-fold prolongation of the ventricular action potential and increased cellular membrane capacitance. 4. Remodelling of ionic currents included marked reduction of both density and absolute magnitude of transient outward (Ito) and inward rectifying (IK1) K¤ currents. The density, but not the absolute magnitude, of basal and isoproterenol (isoprenaline)-stimulated Ca¥ current (ICa) was decreased by 42% and the inactivation kinetics of ICa were significantly slowed. Na¤ current density was suppressed by 50%, but its steady-state activation and inactivation were shifted to more positive potentials. The density of Na¤-Ca¥ exchange current was increased by 35%. 5. In CSQ but not in control myocytes dialysed with cAMP, isoproterenol continued to enhance ICa. This apparent lower responsiveness of ICa to cAMP could be reversed by the nonhydrolysable cAMP analogue 8-Br-cAMP or the phosphodiesterase inhibitor IBMX, suggesting high phosphodiesterase activity of CSQ myocytes. 6. In young CSQ mice (< 60 days) with compensated cardiac hypertrophy, only Ito was significantly suppressed. All other currents remained relatively intact. 7. An increase in cardiac Ca¥-storage capability by overexpression of CSQ results in a dilated cardiomyopathy with tissue fibrosis, calcifications, impaired â-adrenergic signalling and progressive remodelling of ionic currents. The extent of the changes in ionic currents was age dependent. 0541Keywords:

This prospective controlled observational cohort study assessed the performance of a novel panel of serum microRNA (miRNA) biomarkers on indicators of concussion, subconcussive impacts, and neurocognitive function in collegiate football players over the playing season. Male collegiate student football athletes participating in a Division I Football Bowl Subdivision of the National Collegiate Athletic Association (NCAA) were enrolled. There were a total of 53 participants included in the study, 30 non-athlete control subjects and 23 male collegiate student football athletes. Neurocognitive assessments and blood samples were taken within the week before the athletic season began and within the week after the last game of the season and measured for a panel of pre-selected miRNA biomarkers. All the athletes had elevated levels of circulating miRNAs at the beginning of the season compared with control subjects (p < 0.001). Athletes with the lowest standard assessment of concussion (SAC) scores at the beginning of the season had the highest levels of miRNAs. The area under the curve (AUC) for predicting pre-season SAC scores were miR-195 (0.90), miR-20a (0.89), miR-151-5p (0.86), miR-505* (0.85), miR-9-3p (0.77), and miR-362-3p (0.76). In athletes with declining neurocognitive function over the season, concentrations of miRNAs increased over same period. There were significant negative correlations with miR-505* (p = 0.011), miR-30d (p = 0.007), miR-92 (p = 0.033), and (p = 0.008). The miRNAs correlating with balance problems were miR-505* (p = 0.007), miR-30d (p = 0.028), and miR-151-5p (p = 0.023). Those correlating with poor reaction times were miR-20a (0.043), miR-505* (p = 0.049), miR-30d (p = 0.031), miR-92 (p = 0.015), and miR-151-5p (p = 0.044). Select miRNAs were associated with baseline concussion assessments at the beginning of the season and with neurocognitive changes from pre to post-season in collegiate football players. Should these findings be replicated in a larger cohort of athletes, these markers could potentially serve as measures of neurocognitive status in athletes at risk for concussion and subconcussive injuries.

Neuroinflammation is a hallmark of several neurodegenerative diseases and disorders, including traumatic brain injury (TBI). Neuroinflammation results in the activation of glial cells which exacerbates the neuroinflammatory process by secretion of pro-inflammatory cytokines and results in disruption of glial transmission networks. The glial cells, including astrocytes, play a critical role in the maintenance of homeostasis in the brain. Activated astrocytes release several factors as part of the inflammatory process including cytokines, proteins, and microRNAs (miRNAs). MiRNAs are noncoding RNA molecules involved in normal physiological processes and disease pathogenesis. MiRNAs have been implicated as important cell signaling molecules, and they are potential diagnostic biomarkers and therapeutic targets for various diseases, including neurological disorders. Exosomal miRNAs released by astrocytic response to neuroinflammation is not yet studied. In this study, primary human astrocytes were activated by IL-1β stimulation and we examined astrocytic exosomal miRNA cargo released in a neuroinflammatory stress model. Results indicate that acute neuroinflammation and oxidative stress induced by IL-1β generates the release of a specific subset of miRNAs via exosomes, which may have a potential role in regulating the inflammatory response. Additionally, these miRNAs may serve as potential biomarkers of neuroinflammation associated with neurological disorders and injuries.

Venezuelan equine encephalitis virus (VEEV) is an alphavirus in the family Togaviridae. VEEV is highly infectious in aerosol form and a known bio-warfare agent that can cause severe encephalitis in humans. Periodic outbreaks of VEEV occur predominantly in Central and South America. Increased interest in VEEV has resulted in a more thorough understanding of the pathogenesis of this disease. Inflammation plays a paradoxical role of antiviral response as well as development of lethal encephalitis through an interplay between the host and viral factors that dictate virus replication. VEEV has efficient replication machinery that adapts to overcome deleterious mutations in the viral genome or improve interactions with host factors. In the last few decades there has been ongoing development of various VEEV vaccine candidates addressing the shortcomings of the current investigational new drugs or approved vaccines. We review the current understanding of the molecular basis of VEEV pathogenesis and discuss various types of vaccine candidates.

Context.-Medical school education has evolved from department-specific memorization of facts to an integrated curriculum presenting knowledge in a contextual manner across traditional disciplines, integrating information, improving retention, and facilitating application to clinical practice. Integration occurs throughout medical school using live data-sharing technologies, thereby providing the student with a framework for lifelong active learning. Incorporation of educational teams during medical school prepares students for team-based patient care, which is also required for pay-for-performance models used in accountable care organizations.Objective.-To develop learning objectives for teaching pathology to medical students. Given the rapid expansion of basic science knowledge of human development, normal function, and pathobiology, it is neither possible nor desirable for faculty to teach, and students to retain, this vast amount of information. Courses teaching the essentials in context and engaging students in the learning process enable them to become lifelong learners. An appreciation of pathobiology and the role of laboratory medicine underlies the modern practice of medicine. As such, all medical students need to acquire 3 basic competencies in pathology: an understanding of disease mechanisms, integration of mechanisms into organ system pathology, and application of pathobiology to diagnostic medicine.Design.-We propose the development of 3 specific competencies in pathology to be implemented nationwide, aimed at disease mechanisms/processes, organ system pathology, and application to diagnostic medicine. Each competency will include learning objectives and a means to assess acquisition, integration, and application of knowledge. The learning objectives are designed to be a living document managed (curated) by a group of pathologists representing Liaison Committee on Medical Education-accredited medical schools nationally.Conclusions.-Development of a coherent set of learning objectives will assist medical students nationally to gain the basic competencies in pathology necessary for clinical practice. Having national standards for competencies preserves schools' independence in specific curriculum design while assuring all students meet the evolving needs of medical practice.

Hemorrhage following whole-body γ-irradiation in a combined injury (CI) model increases mortality compared to whole-body γ-irradiation alone (RI). The decreased survival in CI is accompanied by increased bone marrow injury, decreased hematocrit, and alterations of miRNA in the kidney. In this study, our aim was to examine cytokine homeostasis, susceptibility to systemic bacterial infection, and intestinal injury. More specifically, we evaluated the interleukin-6 (IL-6)-induced stress proteins including C-reactive protein (CRP), complement 3 (C3), Flt-3 ligand, and corticosterone. CD2F1 male mice received 8.75 Gy 60Co gamma photons (0.6 Gy/min, bilateral) which was followed by a hemorrhage of 20% of the blood volume. In serum, RI caused an increase of IL-1, IL-2, IL-3, IL-5, IL-6, IL-12, IL-13, IL-15, IL-17A, IL-18, G-CSF, CM-CSF, eotaxin, IFN-γ, MCP-1, MIP, RANTES, and TNF-α, which were all increased by hemorrhage alone, except IL-9, IL-17A, and MCP-1. Nevertheless, CI further elevated RI-induced increases of these cytokines except for G-CSF, IFN- γ and RANTES in serum. In the ileum, hemorrhage in the CI model significantly enhanced RI-induced IL-1β, IL-3, IL-6, IL-10, IL-12p70, IL-13, IL-18, and TNF-α concentrations. In addition, Proteus mirabilis Gram(-) was found in only 1 of 6 surviving RI mice on Day 15, whereas Streptococcus sanguinis Gram(+) and Sphingomonas paucimobilis Gram(-) were detected in 2 of 3 surviving CI mice (with 3 CI mice diseased due to inflammation and infection before day 15) at the same time point. Hemorrhage in the CI model enhanced the RI-induced increases in C3 and decreases in CRP concentrations. However, hemorrhage alone did not alter the basal levels, but hemorrhage in the CI model displayed similar increases in Flt-3 ligand levels as RI did. Hemorrhage alone altered the basal levels of corticosterone early after injury, which then returned to the baseline, but in RI mice and CI mice the increased corticosterone concentration remained elevated throughout the 15 day study. CI increased 8 miRNAs and decreased 10 miRNAs in serum, and increased 16 miRNA and decreased 6 miRNAs in ileum tissue. Among the altered miRNAs, CI increased miR-34 in the serum and ileum which targeted an increased phosphorylation of ERK, p38, and increased NF-κB, thereby leading to increased iNOS expression and activation of caspase-3 in the ileum. Further, let-7g/miR-98 targeted the increased phosphorylation of STAT3 in the ileum, which is known to bind to the iNOS gene. These changes may correlate with cell death in the ileum of CI mice. The histopathology displayed blunted villi and villus edema in RI and CI mice. Based on the in silico analysis, miR-15, miR-99, and miR-100 were predicted to regulate IL-6 and TNF. These results suggest that CI-induced alterations of cytokines/chemokines, CRP, and C3 cause a homeostatic imbalance and may contribute to the pathophysiology of the gastrointestinal injury. Inhibitory intervention in these responses may prove therapeutic for CI and improve recovery of the ileal morp...