Seeking a spotless mind: extinction, deconsolidation, and erasure of fear memory

Learning to contend with threats in the environment is essential to survival, but dysregulation of memories for traumatic events can lead to disabling psychopathology. Recent years have witnessed an impressive growth in our understanding of the neural systems and synaptic mechanisms underlying emotional memory formation. As a consequence, interest has emerged in developing strategies for suppressing, if not eliminating, fear memories. Here, I review recent work employing sophisticated behavioral, pharmacological, and molecular tools to target fear memories, placing these memories firmly behind the crosshairs of neurobiologically informed interventions.     

Methicillin-resistant Staphylococcus aureus Bacterial Nitric-oxide Synthase Affects Antibiotic Sensitivity and Skin Abscess Development

Staphylococcus aureus infections present an enormous global health concern complicated by an alarming increase in antibiotic resistance. S. aureus is among the few bacterial species that express nitric-oxide synthase (bNOS) and thus can catalyze NO production from l-arginine. Here we generate an isogenic bNOS-deficient mutant in the epidemic community-acquired methicillin-resistant S. aureus (MRSA) USA300 clone to study its contribution to virulence and antibiotic susceptibility. Loss of bNOS increased MRSA susceptibility to reactive oxygen species and host cathelicidin antimicrobial peptides, which correlated with increased MRSA killing by human neutrophils and within neutrophil extracellular traps. bNOS also promoted resistance to the pharmaceutical antibiotics that act on the cell envelope such as vancomycin and daptomycin. Surprisingly, bNOS-deficient strains gained resistance to aminoglycosides, suggesting that the role of bNOS in antibiotic susceptibility is more complex than previously observed in Bacillus species. Finally, the MRSA bNOS mutant showed reduced virulence with decreased survival and smaller abscess generation in a mouse subcutaneous infection model. Together, these data indicate that bNOS contributes to MRSA innate immune and antibiotic resistance phenotypes. Future development of specific bNOS inhibitors could be an attractive option to simultaneously reduce MRSA pathology and enhance its susceptibility to commonly used antibiotics.     

Epigenetic Mechanisms Regulate Stem Cell Expressed Genes Pou5f1 and Gfra1 in a Male Germ Cell Line

Male fertility is declining and an underlying cause may be due to environment-epigenetic interactions in developing sperm, yet nothing is known of how the epigenome controls gene expression in sperm development. Histone methylation and acetylation are dynamically regulated in spermatogenesis and are sensitive to the environment. Our objectives were to determine how histone H3 methylation and acetylation contribute to the regulation of key genes in spermatogenesis. A germ cell line, GC-1, was exposed to either the control, or the chromatin modifying drugs tranylcypromine (T), an inhibitor of the histone H3 demethylase KDM1 (lysine specific demethylase 1), or trichostatin (TSA), an inhibitor of histone deacetylases, (HDAC). Quantitative PCR (qPCR) was used to identify genes that were sensitive to treatment. As a control for specificity the Myod1 (myogenic differentiation 1) gene was analyzed. Chromatin immunoprecipitation (ChIP) followed by qPCR was used to measure histone H3 methylation and acetylation at the promoters of target genes and the control, Myod1. Remarkably, the chromatin modifying treatment specifically induced the expression of spermatogonia expressed genes Pou5f1 and Gfra1. ChIP-qPCR revealed that induction of gene expression was associated with a gain in gene activating histone H3 methylation and acetylation in Pou5f1 and Gfra1 promoters, whereas CpG DNA methylation was not affected. Our data implicate a critical role for histone H3 methylation and acetylation in the regulation of genes expressed by spermatogonia – here, predominantly mediated by HDAC-containing protein complexes.     

Proximate mechanisms of reproductive monopolization in male moustached tamarins (Saguinus mystax)

In moustached tamarin (Saguinus mystax) groups, the single breeding female mates polyandrously with most or all nonrelated adult males. Nonetheless, paternity is monopolized in many groups by a single male. No evidence for male endocrine suppression has been found in this species. The proximate mechanisms of monopolization thus remain poorly understood. The aim of this study was to investigate the possible impact of agonistic interactions and mate-guarding on the monopolization of paternity in male moustached tamarins. Furthermore, we evaluated the likely costs of these behaviors, and whether olfactory cues might be used for its timing. We used behavioral data on proximity, agonistic interactions, time budgets, and scent-marking behavior to answer these questions. While direct agonistic competition does not play a prominent role, fertile females were consorted in some periods by one male, the sire of the previous and next litter. Consorting was instigated nearly exclusively by the male. It probably occurred during the female's periods of highest fertility, and thus likely functions as mate-guarding. The timing of the consortship was probably guided by olfactory cues in the female's scent marks. While we did not obtain direct evidence for energy costs in terms of increased energy expenditure or decreased food intake, we found that consorting males are more conspicuous and therefore may be more vulnerable to predators.     

Invasion by activated macrophages requires delivery of nascent membrane‐type‐1 matrix metalloproteinase through late endosomes/lysosomes to the cell surface

Macrophage migration into injured or infected tissue is a key aspect in the pathophysiology of many diseases where inflammation is a driving factor. Membrane‐type‐1 matrix metalloproteinase (MT1‐MMP) cleaves extracellular matrix components to facilitate invasion. Here we show that, unlike the constitutive MT1‐MMP surface recycling seen in cancer cells, unactivated macrophages express low levels of MT1‐MMP. Upon lipopolysaccharide (LPS) activation, MT1‐MMP synthesis dramatically increases 10‐fold at the surface by 15 hours. MT1‐MMP is trafficked from the Golgi complex to the surface via late endosomes/lysosomes in a pathway regulated by the late endosome/lysosome R‐SNAREs VAMP7 and VAMP8. These form two separate complexes with the surface Q‐SNARE complex Stx4/SNAP23 to regulate MT1‐MMP delivery to the plasma membrane. Loss of either one of these SNAREs leads to a reduction in surface MT1‐MMP, gelatinase activity and reduced invasion. Thus, inhibiting MT1‐MMP transport through this pathway could reduce macrophage migration and the resulting inflammation.     

Evaluation of the Becton Dickinson Rapid Influenza Diagnostic Tests in Outpatients in Germany during Seven Influenza Seasons

BackgroundAn extensive retrospective study spanning several seasons was undertaken to evaluate the diagnostic performance of the BD rapid influenza diagnostic test (RIDT) in comparison with the RT-PCR assay.MethodsA total of 2,179 respiratory samples were tested in parallel by in-house RT-PCR and the RIDT. During the 2003-2004, 2006-2007, 2007-2008, and 2008-2009 (n=1671) seasons, the BD Directigen Flu A+B test was used, and during the 2010-2011, 2011-2012 and 2012-2013 (n=508) seasons, the BD Directigen EZ Flu A+B test b was used.ResultsThe sensitivity, specificity, PPV and NPV for the BD Directigen Flu A+B test calculated for types A and B together were 39%, 99%, 98%, and 56%, respectively. For the BD Directigen EZ Flu A+B test, these values were 47%, 100%, 100%, 55%, respectively. The sensitivity of the BD Directigen Flu A+B test did not differ significantly from season to season or between types A (44%) and B (37%). The sensitivity of the BD Directigen EZ Flu A+B test calculated for type A only was 59%, which was considerably higher than the sensitivity of this test for type B (23%). The sensitivity of the RIDT was approximately 40-50% in children and teenagers, but it was only 18.% in adults aged 20 years and older. The specificity of both RIDTs was very high (>99%) during all seasons.ConclusionsDue to their rapid turnaround time, RIDTs can help guide decisions about the clinical management of influenza. Because of the high specificity, a positive result can be interpreted as a true positive, and antiviral therapy as well as appropriate measures to prevent the transmission of influenza can be initiated. The best sensitivity of the RIDT is achieved in children. However, even in this group, the RIDT will only recognize influenza infection in approximately half of the cases, and influenza should still be considered in patients with negative results; negative RIDT results must be confirmed by PCR.     

Orally Disintegrating Films and Mini-Tablets—Innovative Dosage Forms of Choice for Pediatric Use

Oral drug delivery is a non-invasive and therefore a very convenient route of administration. Orally disintegrating dosage forms, like soluble films and (mini-)tablets, appear promising for use in the pediatric population. New guidance for the development of pediatric medicines has been published, which provides considerations on how pediatric products should be designed. However, most of the considerations leave a lot of room for interpretations. Bearing in mind the different aspects discussed in the latest guideline, the use of orally disintegrating films and tablets, in particular, small-sized tablets, is discussed and reflected upon by providing evidence from the scientific literature. The available dosage forms for children are various and examples of currently licensed products for use in the pediatric population were compiled. Aspects such as the appropriateness for pediatrics, the choice of excipients, the opportunities for modified drug release preparations or fixed-dose combinations, the acceptability and palatability, and also limitations were discussed with respect to the new dosage forms of orally disintegrating films and mini-tablets. This paper points out that innovation in pediatric medicines are planned and should be encouraged; however, supported by the regulatory guidance, only general considerations are provided. Nevertheless, the guideline summarizes multiple points to consider during the development of medicines for pediatric use. Considering the scientific evidence and the regulatory guidance, orally disintegrating dosage forms, like soluble films and (mini-)tablets, offer an innovative solution for pediatric drug delivery.KEY WORDS: children, orally disintegrating dosage forms, pediatric drug delivery, pediatrics, orodispersible films and tablets