Pharmacokinetics of the cyclosporine-ketoconazole interaction in dogs

Numerous clinical reports have documented an increase in trough blood concentrations of cyclosporine in transplant recipients treated concomitantly with ketoconazole. The objective of this study was to elucidate the mechanism(s) underlying the cyclosporine-ketoconazole interaction using a choledochoureterostomy dog model. Five male beagle dogs received a 4 mg/kg, i.v. bolus dose of cyclosporine either alone or on day seven of a 10-day, 13 mg/kg/day, oral dosing regimen of ketoconazole. Blood samples were collected prior to and at predetermined times for 60 hrs after the cyclosporine dose, while the bile/urine mixture was collected quantitatively for 96 hours after the cyclosporine dose. Ketoconazole decreased the systemic clearance of cyclosporine from 7.0 ml/min/kg to 2.5 ml/min/kg. The terminal disposition rate constant was also decreased significantly from 0.0794 to 0.0354 hrs-1. Ketoconazole caused no significant changes in cyclosporine steady state volume of distribution, or plasma unbound fraction. Ketoconazole did not significantly alter the excretion of cyclosporine and various cyclosporine metabolites in the bile/urine mixture. Inhibition of hepatic drug metabolizing enzymes appears to be the primary reason for the ketoconazole induced elevation in cyclosporine concentration

TLR7-mediated skin inflammation remotely triggers chemokine expression and leukocyte accumulation in the brain

Background: The relationship between the brain and the immune system has become increasingly topical as, although it is immune-specialised, the CNS is not free from the influences of the immune system. Recent data indicate that peripheral immune stimulation can significantly affect the CNS. But the mechanisms underpinning this relationship remain unclear. The standard approach to understanding this relationship has relied on systemic immune activation using bacterial components, finding that immune mediators, such as cytokines, can have a significant effect on brain function and behaviour. More rarely have studies used disease models that are representative of human disorders. Methods: Here we use a well-characterised animal model of psoriasis-like skin inflammation—imiquimod—to investigate the effects of tissue-specific peripheral inflammation on the brain. We used full genome array, flow cytometry analysis of immune cell infiltration, doublecortin staining for neural precursor cells and a behavioural read-out exploiting natural burrowing behaviour. Results: We found that a number of genes are upregulated in the brain following treatment, amongst which is a subset of inflammatory chemokines (CCL3, CCL5, CCL9, CXCL10, CXCL13, CXCL16 and CCR5). Strikingly, this model induced the infiltration of a number of immune cell subsets into the brain parenchyma, including T cells, NK cells and myeloid cells, along with a reduction in neurogenesis and a suppression of burrowing activity. Conclusions: These findings demonstrate that cutaneous, peripheral immune stimulation is associated with significant leukocyte infiltration into the brain and suggest that chemokines may be amongst the key mediators driving this response

Trim17, novel E3 ubiquitin-ligase, initiates neuronal apoptosis

Accumulating data indicate that the ubiquitin-proteasome system controls apoptosis by regulating the level and the function of key regulatory proteins. In this study, we identified Trim17, a member of the TRIM/RBCC protein family, as one of the critical E3 ubiquitin ligases involved in the control of neuronal apoptosis upstream of mitochondria. We show that expression of Trim17 is increased both at the mRNA and protein level in several in vitro models of transcription-dependent neuronal apoptosis. Expression of Trim17 is controlled by the PI3K/Akt/GSK3 pathway in cerebellar granule neurons (CGN). Moreover, the Trim17 protein is expressed in vivo, in apoptotic neurons that naturally die during post-natal cerebellar development. Overexpression of active Trim17 in primary CGN was sufficient to induce the intrinsic pathway of apoptosis in survival conditions. This pro-apoptotic effect was abolished in Bax(-/-) neurons and depended on the E3 activity of Trim17 conferred by its RING domain. Furthermore, knock-down of endogenous Trim17 and overexpression of dominant-negative mutants of Trim17 blocked trophic factor withdrawal-induced apoptosis both in CGN and in sympathetic neurons. Collectively, our data are the first to assign a cellular function to Trim17 by showing that its E3 activity is both necessary and sufficient for the initiation of neuronal apoptosis. Cell Death and Differentiation (2010) 17, 1928-1941; doi: 10.1038/cdd.2010.73; published online 18 June 201

Novel intracellular mechanisms of NMDA receptor-dependent spinal nociceptive plasticity

Prolonged activation of spinal NMDA receptors, after peripheral inflammation or nerve damage, can activate intracellular signalling cascades leading to plastic changes in synaptic transmission. This results in central sensitization of dorsal horn sensory neurones and manifests in patients as increased sensitivity to painful stimuli (hyperalgesia), and pain resulting from normally non-painful tactile stimuli (allodynia). Therefore, targeting NMDA-mediated intracellular signalling pathways could be a successful analgesic strategy, potentially devoid of side-effects associated with receptor blockade. NMDA receptors bind to the intracellular scaffold protein PSD-95, which couples the receptor to cytoplasmic effector pathways. The role of this coupling in spinal sensory transmission and nociceptive plasticity was investigated using biochemical, electrophysiological and behavioural methods. Disruption of binding between PSD-95 and NR2B subunits of NMDA receptors was achieved through the use of a decoy mimetic peptide, Tat-NR2B9c. I show that Tat-NR2B9c selectively reduces wind-up of dorsal horn wide dynamic range neurones and prevents both neuronal and behavioural measures of formalin-induced central sensitization. In the spinal nerve ligation model of chronic pain, Tat-NR2B9c reduced neuronal responses to mechanical and thermal stimulation and was able to reverse behavioural mechanical and cold hypersensitivity, clinical signs of neuropathic pain. In addition, the roles of two kinases, atypical PKCζ/PKMζ and PI3K, known to be involved in hippocampal LTP, were investigated using biochemical, immunohistochemical, electrophysiological and behavioural measures. I found that activation of spinal PKCζ/PKMζ is dependent on coupling between NR2B-subtype receptors and PSD-95, and contributes to central sensitization of dorsal horn neurones. PI3K was also found to be active in the NMDA-dependent formalin model and regulates various intracellular mechanisms in central sensitization. Finally, I investigated the role of DDAH-1, an enzyme which is involved in the regulation of nNOS, in spinal nociceptive plasticity. DDAH-1 inhibition reduced neuronal wind-up and both neuronal and behavioural measures of formalin-induced central sensitization. These findings further our understanding of NMDA-dependent spinal nociceptive plasticity. Disrupting the interaction between NR2B-containing NMDA receptors and PSD-95 or inhibition of downstream intracellular signalling pathways may be successful analgesic strategies for the treatment of chronic pain

Editorial : Predictive mechanisms in action, perception, cognition, and clinical disorders

Acknowledgments The authors would like to acknowledge their funding sources (NIH F32 MH117933 to AD, Alon Fellowship to LR).Peer reviewedPublisher PD

Microsecond Time-Resolved Absorption Spectroscopy Used to Study CO Compounds of Cytochrome bd from Escherichia coli

Cytochrome bd is a tri-heme (b558, b595, d) respiratory oxygen reductase that is found in many bacteria including pathogenic species. It couples the electron transfer from quinol to O2 with generation of an electrochemical proton gradient. We examined photolysis and subsequent recombination of CO with isolated cytochrome bd from Escherichia coli in oneelectron reduced (MV) and fully reduced (R) states by microsecond time-resolved absorption spectroscopy at 532-nm excitation. Both Soret and visible band regions were examined. CO photodissociation from MV enzyme possibly causes fast (t,1.5 ms) electron transfer from heme d to heme b595 in a small fraction of the protein, not reported earlier. Then the electron migrates to heme b558 (t,16 ms). It returns from the b-hemes to heme d with t,180 ms. Unlike cytochrome bd in the R state, in MV enzyme the apparent contribution of absorbance changes associated with CO dissociation from heme d is small, if any. Photodissociation of CO from heme d in MV enzyme is suggested to be accompanied by the binding of an internal ligand (L) at the opposite side of the heme. CO recombines with heme d (t,16 ms) yielding a transient hexacoordinate state (CO-Fe2+ -L). Then the ligand slowly (t,30 ms) dissociates from heme d. Recombination of CO with a reduced heme b in a fraction of the MV sample may also contribute to the 30-ms phase. In R enzyme, CO recombines to heme d (t,20 ms), some heme b558 (t,0.2–3 ms), and finally migrates from heme d to heme b595 (t,24 ms) in ,5% of the enzyme population. Data are consistent with the recent nanosecond study of Rappaport et al. conducted on the membranes at 640-nm excitation but limited to the Soret band. The additional phases were revealed due to differences in excitation and other experimental conditions

A narrative review on the similarities and dissimilarities between myalgic encephalomyelitis/chronic fatigue syndrome (me/cfs) and sickness behavior

It is of importance whether myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a variant of sickness behavior. The latter is induced by acute infections/injury being principally mediated through proinflammatory cytokines. Sickness is a beneficial behavioral response that serves to enhance recovery, conserves energy and plays a role in the resolution of inflammation. There are behavioral/symptomatic similarities (for example, fatigue, malaise, hyperalgesia) and dissimilarities (gastrointestinal symptoms, anorexia and weight loss) between sickness and ME/CFS. While sickness is an adaptive response induced by proinflammatory cytokines, ME/CFS is a chronic, disabling disorder, where the pathophysiology is related to activation of immunoinflammatory and oxidative pathways and autoimmune responses. While sickness behavior is a state of energy conservation, which plays a role in combating pathogens, ME/CFS is a chronic disease underpinned by a state of energy depletion. While sickness is an acute response to infection/injury, the trigger factors in ME/CFS are less well defined and encompass acute and chronic infections, as well as inflammatory or autoimmune diseases. It is concluded that sickness behavior and ME/CFS are two different conditions

Automated Gaze-Based Mind Wandering Detection during Computerized Learning in Classrooms

We investigate the use of commercial off-the-shelf (COTS) eye-trackers to automatically detect mind wandering—a phenomenon involving a shift in attention from task-related to task-unrelated thoughts—during computerized learning. Study 1 (N = 135 high-school students) tested the feasibility of COTS eye tracking while students learn biology with an intelligent tutoring system called GuruTutor in their classroom. We could successfully track eye gaze in 75% (both eyes tracked) and 95% (one eye tracked) of the cases for 85% of the sessions where gaze was successfully recorded. In Study 2, we used this data to build automated student-independent detectors of mind wandering, obtaining accuracies (mind wandering F1 = 0.59) substantially better than chance (F1 = 0.24). Study 3 investigated context-generalizability of mind wandering detectors, finding that models trained on data collected in a controlled laboratory more successfully generalized to the classroom than the reverse. Study 4 investigated gaze- and video- based mind wandering detection, finding that gaze-based detection was superior and multimodal detection yielded an improvement in limited circumstances. We tested live mind wandering detection on a new sample of 39 students in Study 5 and found that detection accuracy (mind wandering F1 = 0.40) was considerably above chance (F1 = 0.24), albeit lower than offline detection accuracy from Study 1 (F1 = 0.59), a finding attributable to handling of missing data. We discuss our next steps towards developing gaze-based attention-aware learning technologies to increase engagement and learning by combating mind wandering in classroom contexts

Using death to one's advantage: HIV modulation of apoptosis

Infection by human immunodeficiency virus (HIV) is associated with an early immune dysfunction and progressive destruction of CD4+ T lymphocytes. This progressive disappearance of T cells leads to a lack of immune control of HIV replication and to the development of immune deficiency resulting in the increased occurrence of opportunistic infections associated with acquired immune deficiency syndrome (AIDS). The HIV-induced, premature destruction of lymphocytes is associated with the continuous production of HIV viral proteins that modulate apoptotic pathways. The viral proteins, such as Tat, Env, and Nef, are associated with chronic immune activation and the continuous induction of apoptotic factors. Viral protein expression predisposes lymphocytes, particularly CD4+ T cells, CD8+ T cells, and antigen-presenting cells, to evolve into effectors of apoptosis and as a result, to lead to the destruction of healthy, non-infected T cells. Tat and Nef, along with Vpu, can also protect HIV-infected cells from apoptosis by increasing anti-apoptotic proteins and down- regulating cell surface receptors recognized by immune system cells. This review will discuss the validity of the apoptosis hypothesis in HIV disease and the potential mechanism(s) that HIV proteins perform in the progressive T cell depletion observed in AIDS pathogenesis. Originally published Leukemia, Vol. 15, No. 3, Mar 200

Neurocognitive mechanisms of co‐occurring math difficulties in dyslexia: Differences in executive function and visuospatial processing

Children with dyslexia frequently also struggle with math. However, studies of reading disability (RD) rarely assess math skill, and the neurocognitive mechanisms underlying co-occurring reading and math disability (RD+MD) are not clear. The current study aimed to identify behavioral and neurocognitive factors associated with co-occurring MD among 86 children with RD. Within this sample, 43% had co-occurring RD+MD and 22% demonstrated a possible vulnerability in math, while 35% had no math difficulties (RD-Only). We investigated whether RD-Only and RD+MD students differed behaviorally in their phonological awareness, reading skills, or executive functions, as well as in the brain mechanisms underlying word reading and visuospatial working memory using functional magnetic resonance imaging (fMRI). The RD+MD group did not differ from RD-Only on behavioral or brain measures of phonological awareness related to speech or print. However, the RD+MD group demonstrated significantly worse working memory and processing speed performance than the RD-Only group. The RD+MD group also exhibited reduced brain activations for visuospatial working memory relative to RD-Only. Exploratory brain-behavior correlations along a broad spectrum of math ability revealed that stronger math skills were associated with greater activation in bilateral visual cortex. These converging neuro-behavioral findings suggest that poor executive functions in general, including differences in visuospatial working memory, are specifically associated with co-occurring MD in the context of RD