Stochastic dynamic causal modeling of working memory connections in cocaine dependence

Although reduced working memory brain activation has been reported in several brain regions of cocaine‐dependent subjects compared with controls, very little is known about whether there is altered connectivity of working memory pathways in cocaine dependence. This study addresses this issue by using functional magnetic resonance imaging‐based stochastic dynamic causal modeling (DCM) analysis to study the effective connectivity of 19 cocaine‐dependent subjects and 14 healthy controls while performing a working memory task. Stochastic DCM is an advanced method that has recently been implemented in SPM8 that can obtain improved estimates, relative to deterministic DCM, of hidden neuronal causes before convolution with the hemodynamic response. Thus, stochastic DCM may be less influenced by the confounding effects of variations in blood oxygen level‐dependent response caused by disease or drugs. Based on the significant regional activation common to both groups and consistent with previous working memory activation studies, seven regions of interest were chosen as nodes for DCM analyses. Bayesian family level inference, Bayesian model selection analyses, and Bayesian model averaging (BMA) were conducted. BMA showed that the cocaine‐dependent subjects had large differences compared with the control subjects in the strengths of prefrontal–striatal modulatory (B matrix) DCM parameters. These findings are consistent with altered cortical–striatal networks that may be related to reduced dopamine function in cocaine dependence. As far as we are aware, this is the first between‐group DCM study using stochastic methodology. Hum Brain Mapp 35:760–778, 2014. © 2012 Wiley Periodicals, Inc.     

The mindful attention and awareness scale is associated with lower levels of high-frequency heart rate variability in a laboratory context

Trait mindfulness has been associated with well-being. A key component of trait mindfulness is intentional attention and awareness which is most commonly measured by the Mindful Attention and Awareness Scale (MAAS). This study investigated the relationship between the MAAS and cardiovascular (HF-HRV, heart rate) reactivity to two laboratory stressors that evoked different patterns of change in heart rate (HR). One stressor (viewing a video of a surgery) evoked HR deceleration while the other stressor (mental arithmetic) evoked HR acceleration. Undergraduate students completed the MAAS and were then exposed to the two stressors while ECG (electrocardiography) was recorded. Findings support the reliability of the stressors to induce expected differential cardiovascular responses and explicate the role of parasympathetic activation. Further, a main effect for MAAS was observed indicating that across laboratory conditions, persons scoring higher on the MAAS had lower HF-HRV relative to persons scoring lower on the MAAS. These findings suggest that higher levels of intentional attention and awareness in a laboratory context might promote parasympathetic withdrawal because these participants were more vigilant, experienced higher cognitive load, and detected more threat cues. Implications for the MAAS and cardiovascular responses to stress are discussed.     

Readmission and reinjury patterns in pediatric assault victims

Pediatric Surgery International - Repeated pediatric assault should be a never event. The purpose of this study was to evaluate the readmission and reinjury patterns in pediatric victims of assault...     

Structure and dynamics of SARS-CoV-2 proofreading exoribonuclease ExoN

High-fidelity replication of the large RNA genome of coronaviruses (CoVs) is mediated by a 3′-to-5′ exoribonuclease (ExoN) in nonstructural protein 14 (nsp14), which excises nucleotides including antiviral drugs misincorporated by the low-fidelity viral RNA-dependent RNA polymerase (RdRp) and has also been implicated in viral RNA recombination and resistance to innate immunity. Here, we determined a 1.6-Å resolution crystal structure of severe acute respiratory syndrome CoV 2 (SARS-CoV-2) ExoN in complex with its essential cofactor, nsp10. The structure shows a highly basic and concave surface flanking the active site, comprising several Lys residues of nsp14 and the N-terminal amino group of nsp10. Modeling suggests that this basic patch binds to the template strand of double-stranded RNA substrates to position the 3′ end of the nascent strand in the ExoN active site, which is corroborated by mutational and computational analyses. We also show that the ExoN activity can rescue a stalled RNA primer poisoned with sofosbuvir and allow RdRp to continue its extension in the presence of the chain-terminating drug, biochemically recapitulating proofreading in SARS-CoV-2 replication. Molecular dynamics simulations further show remarkable flexibility of multidomain nsp14 and suggest that nsp10 stabilizes ExoN for substrate RNA binding to support its exonuclease activity. Our high-resolution structure of the SARS-CoV-2 ExoN–nsp10 complex serves as a platform for future development of anticoronaviral drugs or strategies to attenuate the viral virulence.

The 29.9-kb single-stranded RNA genome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the global COVID-19 pandemic, is replicated and transcribed by the viral RNA-dependent RNA polymerase (RdRp, nsp12) (1–3). Unlike the high-fidelity cellular replicative DNA polymerases, viral RdRp enzymes, including the CoV RdRp, do not contain a proofreading exonuclease domain to ensure high fidelity. The resulting higher mutation rate (10⁻⁴ to 10⁻⁶ substitutions per nucleotide per round of replication) is generally thought to promote rapid viral adaptation in response to selective pressure (4–6). However, the lack of proofreading activity in RdRp poses a particular challenge for the replication of CoVs, which feature the largest known RNA virus genomes (27 to 32 kb, up to twice the length as the next-largest nonsegmented RNA viral genomes) (7, 8). It has been reported that SARS-CoV nsp12 is the fastest viral RdRp known but with an error rate more than one order of magnitude higher than the generally admitted error rate of viral RdRps (9), clearly necessitating a unique proofreading mechanism.To mitigate the low fidelity of RdRp, all coronaviruses encode a 3′-to-5′ exoribonuclease (ExoN) in multifunctional nsp14 (10–12), which forms a complex with nsp10 critical for the ExoN activity, and additionally contains a C-terminal guanine N7 methyl transferase (N7-MTase) domain. Mutations of SARS-CoV-2 nsp14 exhibit strong association with increased genome-wide mutation load (13, 14), and genetic inactivation of ExoN in engineered SARS-CoV and murine hepatitis virus (MHV) leads to 15- to 20-fold increases in mutation rates (7, 15, 16). Furthermore, in a mouse model, SARS-CoV with inactivated ExoN shows a mutator phenotype with decreased fitness and lower virulence over serial passage, suggesting a potential strategy for generating a live, impaired-fidelity coronavirus vaccine (17). Alternatively, recent studies show that ExoN inactivation abrogates replication of SARS-CoV-2 and Middle East Respiratory Syndrome CoV (18), hinting at additional functions for ExoN in viral replication. Indeed, ExoN activity has been reported to mediate the extensive viral RNA recombination required for subgenomic messenger RNA (mRNA) synthesis during normal replication of CoVs, including SARS-CoV-2 (19), and it was shown to be required for resistance to the antiviral innate immune response for MHV (20). ExoN inactivation also significantly increases the sensitivity of CoVs to nucleoside analogs that target RdRp, which is consistent with the biochemical activity of ExoN to excise mutagenic or chain-terminating nucleotides misincorporated by RdRp (21–23). These observations combine to suggest that chemical inhibition of ExoN could be an effective antiviral strategy against CoVs. In this study, we determined high-resolution crystal structures of the SARS-CoV-2 ExoN–nsp10 complex and studied its biochemical activities. Furthermore, we used molecular dynamics (MD) simulations to better understand the dynamics of nsp14, nsp10, and their interaction with RNA.     

Chronopharmacology of hydrocortisone and 9α-fluorhydrocortisone in the treatment for congenital adrenal hyperplasia

The conventional treatment of CAH with hydrocortisone (16–19 mg/m² per day) and 9-F-cortisol (just enough to normalise renin concentrations, started at 07:00 h) was inffective in suppressing the early morning rise of 17-OH-progesterone and in turn androgens in about 20% of our patients. The present work explored the effect of a modified dosage regimen of the drug in five patients. The schedule was: 03:00 h F 33%+9-F-F 33%; 07:00 h F 30%; 12:00 h F 22%+9-F-F 33%; 17:30 h F 15%+9-F-F 33%.Monitored levels of circulating 17-OH-progesterone, testosterone, and individual urinary 17-ketosteroids showed significant improvement, which was not achieved by giving higher or later evening doses. Menarche was induced in two girls (bone age 15 years). The modified dosage schedule offers on the one hand the possibility of better management of CAH, and on the other, cuts down the risk of enhanced Cushing-like effects, which in animal models have been related frequently to dosage schedules not corresponding to the circadian rhythm. The difficulty of administering the drugs at 03:00 h should be overcome by the development of a late-releasing preparation.Abbreviation CAH congenital adrenal hyperplasia This work was presented in part on the 80th Annual Meeting of the Deutsche Gesellschaft für Kinderheilkunde, September 16–19, 1984, in Tübingen     

Quality management in German health care--the EFQM Excellence Model

A brief insight into the issues affecting German health care is given. Namely, upward pressure on costs leads to increasing expenditure within health care and downward pressure from economic recession and political unwillingness to increase taxes and budget spending. In the case of competing key stakeholder perspectives, a quality management framework is seen as a potential approach for addressing these issues. The framework is the European Foundation for Quality Management (EFQM) Excellence Model. The article briefly explains the pilot phase for utilising the EFQM Excellence Model within German health care organisations and the various implementation approaches recommended by EFQM. Specific details of an approach used by a health care organisation within Germany (providing social medicine, geriatric and elderly services) are described in detail. The benefits achieved from using the Model are a clear picture of where the gaps are in the organisation and a clear vision for concentrating future efforts towards total quality management.     

Pseudopituitary dwarfism due to resistance to somatomedin: A new syndrome

The case of an infant is described who at birth was already small and postnatally grew extremely slowly. At age 3 the girl's height was 65 cm, weight 5.6 kg, bone age 21 months. Basal plasma GH was 36–66 ng/ml, basal SM activity was rather high, being around 2.0 U/ml. RIA- and RRA-SM were also increased. Prolonged GH administration did not raise plasma SM. There was a tendency for hypoglycemic episodes in the presence of low insulin levels. Receptor studies with skin fibroblasts showed a diminution of the specific binding of SM-C by 50%.Apparently only the specific IGF-receptor is defective whereas the insulin receptor responds to the increased SM with hypoglycemia. The observation that the high plasma SM did not suppress the enhanced GH-secretion suggests that perhaps the hypothalamic IGF-receptor was also defective.Dedicated to Professor G. Joppich at his 80th birthday