How actual motor competence and perceived motor competence influence motor‐skill engagement of a novel cycling task

In early childhood, factors that contribute to motor‐skill engagement (MSE) are unknown. Our aim was to explore the relationships between actual and perceived motor competence and their influences on MSE on a balance bike (bike with no pedals). A secondary aim was to investigate whether MSE had an effect on ability on a balance bike. This study comprised of 45 children (29% female) aged 4.5 ± 0.5 years. MSE was assessed using distance travelled on a balance bike over an 8‐week period. Actual motor competence was assessed using the Movement Assessment Battery for Children, second edition. Perceived motor competence was assessed using the Pictorial Scale of Perceived Movement Skill Competence. Ability on a balance bike was measured using timed trials on a specifically designed track. Pearson product‐moment correlations were used to assess relationships between actual and perceived motor competence and ability on a balance bike. Linear regressions were used to examine whether actual or perceived motor competence or ability on a balance bike predicted MSE. Repeated measures ANOVA was used to examine whether there was a difference in ability on a balance bike between three MSE groups over 8 weeks. No relationships were found, and none of the variables predicted MSE. There was a significant difference between the MSE groups on ability on a balance bike over time (P = 0.019). Investigating the contributors to MSE on a novel cycling task during early childhood provides knowledge to ensure children are given the best opportunities for practice and acquisition of skills.     

Eurotransplant donor‐risk‐index and recipient factors: influence on long‐term outcome after liver transplantation – A large single‐center experience

The organ shortage has led to increased use of marginal organs. The Eurotransplant Donor‐Risk‐Index (ET‐DRI) was established to estimate outcome after Liver Transplantation (LT). Currently, data on impact of ET‐DRI on long‐term outcome for different indications and recipient conditions are missing. Retrospective, single‐center analysis of long‐term graft survival (GS) of 1767 adult primary LTs according to indication, labMELDcategory (1: ≤18; 2: >18–25; 3: >25–35; 4: >35), and ET‐DRI. Mean ET‐DRI in our cohort was 1.63 (±0.43). One‐, 10, and 15‐yr GS was 83.5%, 63.3%, and 54.8%. Long‐term GS was significantly influenced by ET‐DRI. Accordingly, four ET‐DRI categories were defined and analyzed with respect to underlying disease. Significant impact of these categories was observed for: Alcohol, cholestatic/autoimmune diseases (CD/AIH), and HCV, but not for HCC, HBV, cryptogenic cirrhosis, and acute liver failure. labMELD categories showed no significant influence on graft, but on patient survival. Matching ET‐DRI categories with labMELD revealed significant differences in long‐term GS for labMELDcategories 1, 2, and 3, but not 4. In multivariate analysis, HCV combined with ET‐DRI > 2 and labMELDcategory 3 combined with ET‐DRI > 2 emerged as negative predictors. To achieve excellent long‐term graft survival, higher risk organs (ET‐DRI > 1.4) should be used restrictively for patients with CD/AIH or HCV. Organs with ET‐DRI > 2 should be avoided in patients with a labMELD of >25–35.     

Carimune NF Liquid is a Safe and Effective Immunoglobulin Replacement Therapy in Patients with Primary Immunodeficiency Diseases

Subjects with primary immune deficiency diseases treated with intravenous immunoglobulin (n=42) received intravenous infusions of Carimune NF Liquid every 3–4 weeks for 6 months without routine premedication. The mean dose/patient/infusion was 278.5–800.7 mg/kg. Also, 80.4% of infusions achieved maximum rates of ≥3.5 mg/kg/min; 32% of infusions were associated with adverse events during or within 48 h of their end (upper 95% confidence interval was 39.4%, meeting the Food and Drug Administration (FDA) criterion for acceptable tolerability), and 54.8% of subjects had at least one temporally associated adverse event considered at least possibly drug-related (headache: 35.7% of subjects, 12.4% of infusions; nausea: 14.3%, 3.5%; myalgia: 14.3%, 3.2%; fatigue: 11.9%, 5.7%). The frequencies of these were highest after the first infusion. There were no serious drug-related adverse events or acute serious bacterial infections. Serum IgG trough levels were unchanged from baseline. Carimune NF Liquid, a ready-to-use, high-concentration, liquid immunoglobulin preparation is safe and effective. On behalf of the study group     

Acute oxygenator occlusion in two cases of polycythemia vera: Bailout strategies

Polycytemia vera (PV) is a rare myeloproliferative neoplasm associated with microcirculatory disturbances, thrombosis and bleeding. Patients suffering from PV have a high risk of perioperative adverse events, but the literature regarding on-pump procedures in PV patients is scarce. We report two cases of acute and severe oxygenator failure during cardiopulmonary bypass and present valid exit scenarios.     

Identification of Subgroups of Schizophrenia Patients With Changes in Either Immune or Growth Factor and Hormonal Pathways

Schizophrenia is a heterogeneous disorder normally diagnosed using the Diagnostic and Statistical Manual of Mental Disorders criteria. However, these criteria do not necessarily reflect differences in underlying molecular abnormalities of the disorder. Here, we have used multiplexed immunoassay analyses to measure immune molecules, growth factors, and hormones important to schizophrenia in acutely ill antipsychotic-naive patients (n = 180) and matched controls (n = 398). We found that using the resulting molecular profiles, we were capable of separating schizophrenia patients into 2 significantly distinct subgroups with predominant molecular abnormalities in either immune molecules or growth factors and hormones. These molecular profiles were tested using an independent cohort, and this showed the same separation into 2 subgroups. This suggests that distinct abnormalities occur in specific molecular pathways in schizophrenia patients. This may be of relevance for intervention studies that specifically target particular molecular mechanisms and could be a first step to further define the complex schizophrenia syndrome based on molecular profiles.Key words: schizophrenia, subtypes, diagnosis, molecular profiling, immune factors, growth factors     

Multifactorial Genetic and Environmental Hedgehog Pathway Disruption Sensitizes Embryos to Alcohol-Induced Craniofacial Defects

Background

Prenatal alcohol exposure (PAE) is perhaps the most common environmental cause of human birth defects. These exposures cause a range of structural and neurological defects, including facial dysmorphologies, collectively known as fetal alcohol spectrum disorders (FASD). While PAE causes FASD, phenotypic outcomes vary widely. It is thought that multifactorial genetic and environmental interactions modify the effects of PAE. However, little is known of the nature of these modifiers. Disruption of the Hedgehog (Hh) signaling pathway has been suggested as a modifier of ethanol teratogenicity. In addition to regulating the morphogenesis of craniofacial tissues commonly disrupted in FASD, a core member of the Hh pathway, Smoothened, is susceptible to modulation by structurally diverse chemicals. These include environmentally prevalent teratogens like piperonyl butoxide (PBO), a synergist found in thousands of pesticide formulations.

Methods

Here, we characterize multifactorial genetic and environmental interactions using a zebrafish model of craniofacial development.

Results

We show that loss of a single allele of shha sensitized embryos to both alcohol- and PBO-induced facial defects. Co-exposure of PBO and alcohol synergized to cause more frequent and severe defects. The effects of this co-exposure were even more profound in the genetically susceptible shha heterozygotes.

Conclusions

Together, these findings shed light on the multifactorial basis of alcohol-induced craniofacial defects. In addition to further implicating genetic disruption of the Hh pathway in alcohol teratogenicity, our findings suggest that co-exposure to environmental chemicals that perturb Hh signaling may be important variables in FASD and related craniofacial disorders.

     

Nonselective cation permeation in an AMPA-type glutamate receptor

Fast excitatory synaptic transmission in the central nervous system relies on the AMPA-type glutamate receptor (AMPAR). This receptor incorporates a nonselective cation channel, which is opened by the binding of glutamate. Although the open pore structure has recently became available from cryo-electron microscopy (Cryo-EM), the molecular mechanisms governing cation permeability in AMPA receptors are not understood. Here, we combined microsecond molecular dynamic (MD) simulations on a putative open-state structure of GluA2 with electrophysiology on cloned channels to elucidate ion permeation mechanisms. Na⁺, K⁺, and Cs⁺ permeated at physiological rates, consistent with a structure that represents a true open state. A single major ion binding site for Na⁺ and K⁺ in the pore represents the simplest selectivity filter (SF) structure for any tetrameric cation channel of known structure. The minimal SF comprised only Q586 and Q587, and other residues on the cytoplasmic side formed a water-filled cavity with a cone shape that lacked major interactions with ions. We observed that Cl⁻ readily enters the upper pore, explaining anion permeation in the RNA-edited (Q586R) form of GluA2. A permissive architecture of the SF accommodated different alkali metals in distinct solvation states to allow rapid, nonselective cation permeation and copermeation by water. Simulations suggested Cs⁺ uses two equally populated ion binding sites in the filter, and we confirmed with electrophysiology of GluA2 that Cs⁺ is slightly more permeant than Na⁺, consistent with serial binding sites preferentially driving selectivity.

Glutamate receptor ion channels are found at synapses throughout the vertebrate nervous system, where they convert submillisecond glutamate signals into cation currents. Advances in structural biology have provided molecular scale maps of their ion pores, permitting comparison with a burgeoning menagerie of structures from related ion channels. It has been comparatively difficult to obtain candidate open pore structures of glutamate receptors, with the notable exceptions being from single-particle cryo-electron microscopy (Cryo-EM) of complexes between GluA2 and Stargazin (1, 2), the prototypical transmembrane AMPA receptor regulatory protein (TARP). However, it is unclear from simple inspection of these structures whether 1) the ion pore is conductive or 2) it is open to its fullest extent or to the highest conductance level. One structure has the unedited form of GluA2 (Q), that is, GluA2 lacking the common RNA editing of the Q586 residue to Arginine (3), while the other structure is of the edited form (Q586R), which should have a low conductance (4). Previous electrophysiological work suggests that the radius of the narrowest part of the AMPA channel [either with or without Stargazin (5, 6)] is 4 Å, and neither the upper gate nor the selectivity filter (SF) are this wide in either candidate open structure. However, these estimates are based on the geometric mean radius of large, elongated cations. A substantial body of electrophysiological work provides good benchmarks for how permeation should proceed in an open AMPA receptor pore. For example, canonical measurements of reversal potentials show that alkali earth cations from sodium (Na⁺) up to cesium (Cs⁺) should permeate GluA1 (7) and GluA2 (Q) (8) approximately equally well and that the single channel conductance of the full level of GluA2 (Q) should be considerable [∼30 pS (9)].Most computational work on ion permeation through channels has been focused on simple, selective potassium (K⁺) channels like KcsA (10–12), being the first reported crystal structures of ion channels (13). Thanks to their minimal sequences, these channels demand little computational overhead. Their key structural features are two membrane-spanning helices and a reentrant loop forming a narrow SF for permeant ions. This core motif defines a superfamily of tetrameric and pseudotetrameric channels that encompass selective, semiselective, and nonselective cation conductances. In common with many eukaryotic channels, the AMPA-type glutamate receptor (AMPAR) has a pore domain whose gating state is controlled by substantially larger domains outside the membrane (amino terminal domain [ATD] and ligand-binding domain [LBD], Fig. 1A), which account for about 75% of the protein mass. The large size presents a challenge for conventional molecular dynamic (MD) simulations, with the AMPA receptor being about six-times bigger than KcsA.Open in a separate windowFig. 1.AMPA receptor and the simulation setup. (A) The activated open state of the AMPA receptor from Cryo-EM [PDB ID: 5WEO (1)] with Stargazin molecules removed. The receptor is composed of ATD, LBD, and TMD. (B) The TMD and linkers to the LBD layer were included the MD simulations. The sites where the linkers were truncated and physically restrained (see Methods) are marked with red balls. Two out of the four subunits are shown. (C) The SF region of the AMPA receptor pore, with key residues labeled. Again, only two diagonally opposed subunits are drawn. (D) The computational electrophysiology setup was composed of two tetrameric AMPA channels, each embedded in a separate POPC lipid bilayer, solvated with water molecules and ions. A small cation imbalance between the two compartments α and β was maintained during the simulations. The resulting gradient gave a transmembrane potential to drive ion permeation.It remains to be seen to what extent key features of ion permeation elucidated in prokaryotic channels (selectivity, discrete sites, desolvated ions, and block by divalent ions) are widely applicable in channels with more substantial architectures. Recent experimental and MD work on nonselective prokaryotic channels like NaK and NaK-CNG as well as a mutant of the human hERG1 channel suggests that ion permeation in these channels differs substantially from classical K⁺-selective ion permeation (14–17). The SF of nonselective cation channels is much more flexible, with fewer ion binding sites leading to distinct conduction mechanisms and hydration states for Na⁺ and K⁺ when passing through the filter. In the AMPA receptor, in one activated open Cryo-EM structure of GluA2 (1), density for a presumptive hydrated sodium ion was observed adjacent to the unedited Q586 residue. In the structure of RNA-edited GluA2 (Q586R) with Stargazin (2), ions were absent. The closed state structure of a GluA1/A2 heteromer featured strong density of unknown identity adjacent to C589 (18). Whether the paucity and heterogeneity of resolved ions is due to a lack of order in the filter region, the lack of detail in the coulomb potential density, or a true deficit of ions remains unclear. However, observations in these AMPA receptor structures are in marked contrast to the Cryo-EM structures of several other nonselective cation channels, such as hyperpolarization-activated cyclic nucleotide-gated (HCN) (19) and cyclic nucleotide-gated (CNG) channels (20), where two or three bound ions were visible. Further context comes from canonical K⁺-selective channels, which feature up to four ions in a row (21), and crystal structures of Ca²⁺-selective transient receptor potential (TRP) channels where two Ca²⁺ ions were readily resolved (22).Here, we used MD-based computational electrophysiology to examine ion permeation through the mammalian AMPA receptor ion channel. We determined that the published structure is stably open, suitably detailed for MD simulations, and most likely represents a native fully open state. We identified a minimal SF consisting of a single major ion binding site that does not fully dehydrate ions. In simulations, Cs⁺ co-opted a secondary binding site. Consistent with multiple sites promoting ion selectivity, electrophysiology of AMPARs in human embryonic kidney (HEK293) cells showed that Cs⁺ is slightly more permeant than Na⁺.