The AMBRA1 E3 ligase adaptor regulates the stability of cyclin D.

The initiation of cell division integrates a large number of intra- and extracellular inputs. D-type cyclins (hereafter, cyclin D) couple these inputs to the initiation of DNA replication1. Increased levels of cyclin D promote cell division by activating cyclin-dependent kinases 4 and 6 (hereafter, CDK4/6), which in turn phosphorylate and inactivate the retinoblastoma tumour suppressor. Accordingly, increased levels and activity of cyclin D-CDK4/6 complexes are strongly linked to unchecked cell proliferation and cancer2,3. However, the mechanisms that regulate levels of cyclin D are incompletely understood4,5. Here we show that autophagy and beclin 1 regulator 1 (AMBRA1) is the main regulator of the degradation of cyclin D. We identified AMBRA1 in a genome-wide screen to investigate the genetic basis of  the response to CDK4/6 inhibition. Loss of AMBRA1 results in high levels of cyclin D in cells and in mice, which promotes proliferation and decreases sensitivity to CDK4/6 inhibition. Mechanistically, AMBRA1 mediates ubiquitylation and proteasomal degradation of cyclin D as a substrate receptor for the cullin 4 E3 ligase complex. Loss of AMBRA1 enhances the growth of lung adenocarcinoma in a mouse model, and low levels of AMBRA1 correlate with worse survival in patients with lung adenocarcinoma. Thus, AMBRA1 regulates cellular levels of cyclin D, and contributes to cancer development and the response of cancer cells to CDK4/6 inhibitors.

A tandem activity-based sensing and labeling strategy reveals antioxidant response element regulation of labile iron pools.

Iron is an essential element for life owing to its ability to participate in a diverse array of oxidation-reduction reactions. However, misregulation of iron-dependent redox cycling can also produce oxidative stress, contributing to cell growth, proliferation, and death pathways underlying aging, cancer, neurodegeneration, and metabolic diseases. Fluorescent probes that selectively monitor loosely bound Fe(II) ions, termed the labile iron pool, are potentially powerful tools for studies of this metal nutrient; however, the dynamic spatiotemporal nature and potent fluorescence quenching capacity of these bioavailable metal stores pose challenges for their detection. Here, we report a tandem activity-based sensing and labeling strategy that enables imaging of labile iron pools in live cells through enhancement in cellular retention. Iron green-1 fluoromethyl (IG1-FM) reacts selectively with Fe(II) using an endoperoxide trigger to release a quinone methide dye for subsequent attachment to proximal biological nucleophiles, providing a permanent fluorescent stain at sites of elevated labile iron. IG1-FM imaging reveals that degradation of the major iron storage protein ferritin through ferritinophagy expands the labile iron pool, while activation of nuclear factor-erythroid 2-related factor 2 (NRF2) antioxidant response elements (AREs) depletes it. We further show that lung cancer cells with heightened NRF2 activation, and thus lower basal labile iron, have reduced viability when treated with an iron chelator. By connecting labile iron pools and NRF2-ARE activity to a druggable metal-dependent vulnerability in cancer, this work provides a starting point for broader investigations into the roles of transition metal and antioxidant signaling pathways in health and disease.

Glial swip-10 controls systemic mitochondrial function, oxidative stress, and neuronal viability via copper ion homeostasis.

Cuprous copper [Cu(I)] is an essential cofactor for enzymes that support many fundamental cellular functions including mitochondrial respiration and suppression of oxidative stress. Neurons are particularly reliant on mitochondrial production of ATP, with many neurodegenerative diseases, including Parkinson's disease, associated with diminished mitochondrial function. The gene MBLAC1 encodes a ribonuclease that targets pre-mRNA of replication-dependent histones, proteins recently found in yeast to reduce Cu(II) to Cu(I), and when mutated disrupt ATP production, elevates oxidative stress, and severely impacts cell growth. Whether this process supports neuronal and/or systemic physiology in higher eukaryotes is unknown. Previously, we identified swip-10, the putative Caenorhabditis elegans ortholog of MBLAC1, establishing a role for glial swip-10 in limiting dopamine (DA) neuron excitability and sustaining DA neuron viability. Here, we provide evidence from computational modeling that SWIP-10 protein structure mirrors that of MBLAC1 and locates a loss of function coding mutation at a site expected to disrupt histone RNA hydrolysis. Moreover, we find through genetic, biochemical, and pharmacological studies that deletion of swip-10 in worms negatively impacts systemic Cu(I) levels, leading to deficits in mitochondrial respiration and ATP production, increased oxidative stress, and neurodegeneration. These phenotypes can be offset in swip-10 mutants by the Cu(I) enhancing molecule elesclomol and through glial expression of wildtype swip-10. Together, these studies reveal a glial-expressed pathway that supports systemic mitochondrial function and neuronal health via regulation of Cu(I) homeostasis, a mechanism that may lend itself to therapeutic strategies to treat devastating neurodegenerative diseases.

S. aureus Eap is a polyvalent inhibitor of neutrophil serine proteases.

Staphylococcus aureus expresses three high-affinity neutrophil serine protease (NSP) inhibitors known as the extracellular adherence protein domain (EAPs) proteins. Whereas EapH1 and EapH2 are comprised of a single EAP domain, the modular extracellular adherence protein (Eap) from S. aureus strain Mu50 consists of four EAP domains. We recently reported that EapH2 can simultaneously bind and inhibit cathepsin-G (CG) and neutrophil elastase (NE), which are the two most abundant NSPs. This unusual property of EapH2 arises from independent CG and NE-binding sites that lie on opposing faces of its EAP domain. Here we used X-ray crystallography and enzyme assays to show that all four individual domains of Eap (i.e. Eap1, Eap2, Eap3, and Eap4) exhibit an EapH2-like ability to form ternary complexes with CG and NE that inhibit both enzymes simultaneously. We found that Eap1, Eap2, and Eap3 have similar functional profiles insofar as NSP inhibition is concerned but that Eap4 displays an unexpected ability to inhibit two NE enzymes simultaneously. Using X-ray crystallography, we determined that this second NE-binding site in Eap4 arises through the same region of its EAP domain that also comprises its CG-binding site. Interestingly, small angle X-ray scattering data showed that stable tail-to-tail dimers of the NE/Eap4/NE ternary complex exist in solution. This arrangement is compatible with NSP-binding at all available sites in a two-domain fragment of Eap. Together, our work implies that Eap is a polyvalent inhibitor of NSPs. It also raises the possibility that higher-order structures of NSP-bound Eap may have unique functional properties.

Oxidation state-specific fluorescent copper sensors reveal oncogene-driven redox changes that regulate labile copper(II) pools.

Copper is an essential metal nutrient for life that often relies on redox cycling between Cu(I) and Cu(II) oxidation states to fulfill its physiological roles, but alterations in cellular redox status can lead to imbalances in copper homeostasis that contribute to cancer and other metalloplasias with metal-dependent disease vulnerabilities. Copper-responsive fluorescent probes offer powerful tools to study labile copper pools, but most of these reagents target Cu(I), with limited methods for monitoring Cu(II) owing to its potent fluorescence quenching properties. Here, we report an activity-based sensing strategy for turn-on, oxidation state-specific detection of Cu(II) through metal-directed acyl imidazole chemistry. Cu(II) binding to a metal and oxidation state-specific receptor that accommodates the harder Lewis acidity of Cu(II) relative to Cu(I) activates the pendant dye for reaction with proximal biological nucleophiles and concomitant metal ion release, thus avoiding fluorescence quenching. Copper-directed acyl imidazole 649 for Cu(II) (CD649.2) provides foundational information on the existence and regulation of labile Cu(II) pools, including identifying divalent metal transporter 1 (DMT1) as a Cu(II) importer, labile Cu(II) increases in response to oxidative stress induced by depleting total glutathione levels, and reciprocal increases in labile Cu(II) accompanied by decreases in labile Cu(I) induced by oncogenic mutations that promote oxidative stress.

Intrinsic and extrinsic determinants of conditional localization of Mms6 to magnetosome organelles in Magnetospirillum magneticum AMB-1.

Magnetotactic bacteria are a diverse group of microbes that use magnetic particles housed within intracellular lipid-bounded magnetosome organelles to guide navigation along geomagnetic fields. The development of magnetosomes and their magnetic crystals in Magnetospirillum magneticum AMB-1 requires the coordinated action of numerous proteins. Most proteins are thought to localize to magnetosomes during the initial stages of organelle biogenesis, regardless of environmental conditions. However, the magnetite-shaping protein Mms6 is only found in magnetosomes that contain magnetic particles, suggesting that it might conditionally localize after the formation of magnetosome membranes. The mechanisms for this unusual mode of localization to magnetosomes are unclear. Here, using pulse-chase labeling, we show that Mms6 translated under non-biomineralization conditions translocates to pre-formed magnetosomes when cells are shifted to biomineralizing conditions. Genes essential for magnetite production, namely mamE, mamM, and mamO, are necessary for Mms6 localization, whereas mamN inhibits Mms6 localization. MamD localization was also investigated and found to be controlled by similar cellular factors. The membrane localization of Mms6 is dependent on a glycine-leucine repeat region, while the N-terminal domain of Mms6 is necessary for retention in the cytosol and impacts conditional localization to magnetosomes. The N-terminal domain is also sufficient to impart conditional magnetosome localization to MmsF, altering its native constitutive magnetosome localization. Our work illuminates an alternative mode of protein localization to magnetosomes in which Mms6 and MamD are excluded from magnetosomes by MamN until biomineralization initiates, whereupon they translocate into magnetosome membranes to control the development of growing magnetite crystals.IMPORTANCEMagnetotactic bacteria (MTB) are a diverse group of bacteria that form magnetic nanoparticles surrounded by membranous organelles. MTB are widespread and serve as a model for bacterial organelle formation and biomineralization. Magnetosomes require a specific cohort of proteins to enable magnetite formation, but how those proteins are localized to magnetosome membranes is unclear. Here, we investigate protein localization using pulse-chase microscopy and find a system of protein coordination dependent on biomineralization-permissible conditions. In addition, our findings highlight a protein domain that alters the localization behavior of magnetosome proteins. Utilization of this protein domain may provide a synthetic route for conditional functionalization of magnetosomes for biotechnological applications.

Characterization of two distinct neutrophil serine protease-binding modes within a Staphylococcus aureus innate immune evasion protein family.

Extracellular adherence protein domain (EAPs) proteins are a class of innate immune evasion proteins secreted by the human pathogen Staphylococcus aureus. EAPs are potent and selective inhibitors of cathepsin-G (CG) and neutrophil elastase (NE), which are the two most abundant neutrophil serine proteases (NSPs). Previous work from our group has shown that the prototypical EAP, EapH1, relies on plasticity within a single inhibitory site to block the activities of CG and NE. However, whether other EAPs follow similar structure-function relationships is unclear. To address this question, we studied the inhibitory properties of the first (Eap1) and second (Eap2) domains of the modular extracellular adherence protein of S. aureus and determined their structures when bound to CG and NE, respectively. We observed that both Eap1 and Eap2 displayed time-dependent inhibition of CG (on the order of 10-9 M) and of NE (on the order of 10-10 M). We also found that whereas the structures of Eap1 and Eap2 bound to CG showed an overall inhibitory mode like that seen previously for EapH1, the structures of Eap1 and Eap2 bound to NE revealed a new inhibitory mode involving a distal region of the EAP domain. Using site-directed mutagenesis of Eap1 and Eap2, along with enzyme assays, we confirmed the roles of interfacial residues in NSP inhibition. Taken together, our work demonstrates that EAPs can form structurally divergent complexes with two closely related serine proteases and further suggests that certain EAPs may be capable of inhibiting two NSPs simultaneously.

New Advances in Understanding Inhibition of Myeloperoxidase and Neutrophil Serine Proteases by Two Families of Staphylococcal Innate Immune Evasion Proteins.

Neutrophils are the most abundant leukocytes in humans and play an important early role in the innate immune response against microorganisms. Neutrophil phagosomes contain high concentrations of antibacterial enzymes, including myeloperoxidase (MPO) and the neutrophil serine proteases (NSPs). These antibacterial enzymes can also be released extracellularly upon degranulation or as a component of neutrophil extracellular traps (NETs). Due to host/pathogen coevolution, S. aureus expresses a diverse arsenal of innate immune evasion proteins that target many aspects of the neutrophil antibacterial response. In the last decade, two new classes of staphylococcal innate immune evasion proteins that act as potent, selective inhibitors of MPO and NSPs, respectively, have been discovered. The Staphylococcal Peroxidase INhibitor (SPIN) is a small ∼8.3 kDa α-helical bundle protein that blocks MPO activity by interfering with substrate and product exchange with the MPO active site. The Extracellular Adherence Protein (EAP) family consists of three unique proteins comprised of one or more copies of an ∼11 kDa ß-grasp domain capable of high-affinity, selective, non-covalent inhibition of NSPs. This brief review article summarizes recent advances in understanding the structural and functional properties of SPIN and EAP family members and outlines some potential avenues for future investigation of these enzyme inhibitors.

Integrative multi-omic sequencing reveals the MMTV-Myc mouse model mimics human breast cancer heterogeneity.

BACKGROUND: Breast cancer is a complex and heterogeneous disease with distinct subtypes and molecular profiles corresponding to different clinical outcomes. Mouse models of breast cancer are widely used, but their relevance in capturing the heterogeneity of human disease is unclear. Previous studies have shown the heterogeneity at the gene expression level for the MMTV-Myc model, but have only speculated on the underlying genetics. METHODS: Tumors from the microacinar, squamous, and EMT histological subtypes of the MMTV-Myc mouse model of breast cancer underwent whole genome sequencing. The genomic data obtained were then integrated with previously obtained matched sample gene expression data and extended to additional samples of each histological subtype, totaling 42 gene expression samples. High correlation was observed between genetic copy number events and resulting gene expression by both Spearman's rank correlation coefficient and the Kendall rank correlation coefficient. These same genetic events are conserved in humans and are indicative of poor overall survival by Kaplan-Meier analysis. A supervised machine learning algorithm trained on METABRIC gene expression data was used to predict the analogous human breast cancer intrinsic subtype from mouse gene expression data. RESULTS: Herein, we examine three common histological subtypes of the MMTV-Myc model through whole genome sequencing and have integrated these results with gene expression data. Significantly, key genomic alterations driving cell signaling pathways were well conserved within histological subtypes. Genomic changes included frequent, co-occurring mutations in KIT and RARA in the microacinar histological subtype as well as SCRIB mutations in the EMT subtype. EMT tumors additionally displayed strong KRAS activation signatures downstream of genetic activating events primarily ascribed to KRAS activating mutations, but also FGFR2 amplification. Analogous genetic events in human breast cancer showed stark decreases in overall survival. In further analyzing transcriptional heterogeneity of the MMTV-Myc model, we report a supervised machine learning model that classifies MMTV-Myc histological subtypes and other mouse models as being representative of different human intrinsic breast cancer subtypes. CONCLUSIONS: We conclude the well-established MMTV-Myc mouse model presents further opportunities for investigation of human breast cancer heterogeneity.

Background suppression for CARS thermometry in highly luminous flames using an electro-optical shutter.

An electro-optical shutter (EOS), comprising a Pockels cell located between crossed-axis polarizers, is integrated into a nanosecond coherent anti-Stokes Raman scattering (CARS) system. The use of the EOS enables thermometry measurements in high-luminosity flames through significant reduction of the background resulting from broadband flame emission. A temporal gating ≤100 ns along with an extinction ratio >10,000:1 are achieved using the EOS. Integration of the EOS enables the use of an unintensified CCD camera for signal detection, improving upon the signal-to-noise ratio achievable with inherently noisy microchannel plate intensification processes previously employed for short temporal gating. The reduction in background luminescence afforded by the EOS in these measurements allows the camera sensor to capture CARS spectra at a broad range of signal intensities and corresponding temperatures, without saturation of the sensor, thus enhancing the dynamic range of these measurements.

A compendium of kinetic modulatory profiles identifies ferroptosis regulators.

Cell death can be executed by regulated apoptotic and nonapoptotic pathways, including the iron-dependent process of ferroptosis. Small molecules are essential tools for studying the regulation of cell death. Using time-lapse imaging and a library of 1,833 bioactive compounds, we assembled a large compendium of kinetic cell death modulatory profiles for inducers of apoptosis and ferroptosis. From this dataset we identify dozens of ferroptosis suppressors, including numerous compounds that appear to act via cryptic off-target antioxidant or iron chelating activities. We show that the FDA-approved drug bazedoxifene acts as a potent radical trapping antioxidant inhibitor of ferroptosis both in vitro and in vivo. ATP-competitive mechanistic target of rapamycin (mTOR) inhibitors, by contrast, are on-target ferroptosis inhibitors. Further investigation revealed both mTOR-dependent and mTOR-independent mechanisms that link amino acid metabolism to ferroptosis sensitivity. These results highlight kinetic modulatory profiling as a useful tool to investigate cell death regulation.

Genetic Evaluation for Hereditary Cancer Syndromes Among African Americans: A Critical Review.

While hereditary cancer syndromes have been described and studied for centuries, the completion of the human genome project fueled accelerated progress in precision medicine due to the introduction of genetic testing in the 1990s, creating avenues for tailored treatments and medical management options. However, genetic testing has not benefited everyone equitably, with nearly all of the published work based on individuals of non-Hispanic White/European ancestry. There remains a gap in knowledge regarding the prevalence, penetrance, and manifestations of common hereditary cancer syndromes in the African-American population due to significant disparities in access and uptake of genetic testing. This review summarizes the available literature on genetic testing for breast, colon, and prostate cancers in the African-American population and explores the disparities in access to genetic testing between non-Hispanic White and African-American patients. This article also addresses the barriers to genetic testing and discrepancies in the uptake of recommendations for hereditary cancer syndromes in the African-American population when compared with non-Hispanic Whites. The review offers practice implications for many healthcare providers and demonstrates gaps in the existing knowledge to be addressed in future studies to help eliminate the persisting health disparities faced by the African-American population.

Hunger Games: Impact of Fasting Guidelines for Orthopedic Procedural Sedation in the Pediatric Emergency Department.

BACKGROUND: Fasting guidelines for pediatric procedural sedation have historically been controversial. Recent literature suggests that there is no difference in adverse events regardless of fasting status. OBJECTIVES: The goal of this study was to examine adverse outcomes and departmental efficiency when fasting guidelines are not considered during pediatric emergency department (PED) sedation for orthopedic interventions. METHODS: Retrospective chart review identified 2674 patients who presented to a level I PED and required procedural sedation for orthopedic injuries between February 2011 and July 2018. This was a level III, retrospective cohort study. Patients were categorized into the following groups: already within American Society of Anesthesiologists (ASA) fasting guidelines on presentation to the PED (n = 671 [25%]), had procedural sedation not within the ASA guidelines (n = 555 [21%]), and had procedural sedation after fasting in the PED to meet ASA guidelines (n = 1448 [54%]). Primary outcomes were length of stay, time from admission to start of sedation, length of sedation, time from end of sedation to discharge, and adverse events. DISCUSSION: There was a significant difference in the length of stay and time from admission to sedation-both approximately 80 min longer in those with procedural sedation after fasting in the PED to meet ASA guidelines (p < 0.001). There was no significant difference among groups in length of sedation or time to discharge after sedation. Adverse events were uncommon, with only 55 total adverse events (0.02%). Vomiting during the recovery phase was the most common (n = 17 [0.006%]). Other notable adverse events included nine hypoxic events (0.003%) and five seizures (0.002%). There was no significant difference in adverse events among the groups. CONCLUSIONS: Length of stay in the PED was significantly longer if ASA fasting guidelines were followed for children requiring sedation for orthopedic procedures. This is a substantial delay in a busy PED where beds and resources are at a premium. Although providing similar care with equivalent outcomes, the value of spending less time in the PED is evident. Overall, adverse events related to sedation are rare and not related to fasting guidelines.

Reminders of Everyday Misinformation Statements Can Enhance Memory for and Beliefs in Corrections of Those Statements in the Short Term.

Fake-news exposure can cause misinformation to be mistakenly remembered and believed. In two experiments (Ns = 96), we examined whether reminders of misinformation could improve memory for and beliefs in corrections. Subjects read factual statements and misinformation statements taken from news websites and then read statements that corrected the misinformation. Misinformation reminders appeared before some corrections but not others. Subjects then attempted to recall facts, indicated their belief in those recalls, and indicated whether they remembered corrections and misinformation. In Experiment 1, we did not constrain subjects' report criteria. But in Experiment 2, we encouraged conservative reporting by instructing subjects to report only information they believed to be true. Reminders increased recall and belief accuracy. These benefits were greater both when misinformation was recollected and when subjects remembered that corrections had occurred. These findings demonstrate one situation in which misinformation reminders can diminish the negative effects of fake-news exposure in the short term.

Enantioconvergent Alkylations of Amines by Alkyl Electrophiles: Copper-Catalyzed Nucleophilic Substitutions of Racemic α-Halolactams by Indoles.

Transition-metal catalysis has the potential to address shortcomings in the classic SN2 reaction of an amine with an alkyl electrophile, both with respect to reactivity and to enantioselectivity. In this study, we describe the development of a user-friendly method (reaction at room temperature, with commercially available catalyst components) for the enantioconvergent nucleophilic substitution of racemic secondary alkyl halides (α-iodolactams) by indoles. Mechanistic studies are consistent with the formation of a copper(I)-indolyl complex that reacts at different rates with the two enantiomers of the electrophile, which interconvert under the reaction conditions (dynamic kinetic resolution). This investigation complements earlier work on photoinduced enantioconvergent N-alkylation, supporting the premise that this important challenge can be addressed by a range of strategies.

Enantioconvergent Cross-Couplings of Alkyl Electrophiles: The Catalytic Asymmetric Synthesis of Organosilanes.

Metal-catalyzed enantioconvergent cross-coupling reactions of alkyl electrophiles are emerging as a powerful tool in asymmetric synthesis. To date, high enantioselectivity has been limited to couplings of electrophiles that bear a directing group or a proximal p/π orbital. Herein, we demonstrate for the first time that enantioconvergent cross-couplings can be achieved with electrophiles that lack such features; specifically, we establish that a chiral nickel catalyst can accomplish Negishi reactions of racemic α-halosilanes with alkylzinc reagents with good enantioselectivity under simple and mild conditions, thereby providing access to enantioenriched organosilanes, an important class of target molecules.

Copper-Catalyzed Alkylation of Aliphatic Amines Induced by Visible Light.

Although the alkylation of an amine by an alkyl halide serves as a "textbook example" of a nucleophilic substitution reaction, the selective mono-alkylation of aliphatic amines by unactivated, hindered halides persists as a largely unsolved challenge in organic synthesis. We report herein that primary aliphatic amines can be cleanly mono-alkylated by unactivated secondary alkyl iodides in the presence of visible light and a copper catalyst. The method operates under mild conditions (-10 °C), displays good functional-group compatibility, and employs commercially available catalyst components. A trapping experiment with TEMPO is consistent with C-N bond formation via an alkyl radical in an out-of-cage process.

Aflatoxin contamination in corn sold for wildlife feed in texas.

Supplemental feeding with corn to attract and manage deer is a common practice throughout Texas. Other species, including northern bobwhites (Colinus virginianus), are commonly seen feeding around supplemental deer feeders. In many cases, supplemental feeding continues year-round so feed supply stores always have supplemental corn in stock. Fluctuating weather and improper storage of corn can lead to and/or amplify aflatoxin contamination. Due to the recent decline of bobwhites throughout the Rolling Plains ecoregion of Texas, there has been interest in finding factors such as toxins that could be linked to their decline. In this study, we purchased and sampled supplemental corn from 19 locations throughout this ecoregion to determine if aflatoxin contamination was present in individual bags prior to being dispersed to wildlife. Of the 57 bags sampled, 33 bags (approximately 58%) contained aflatoxin with a bag range between 0.0-19.91 parts per billion (ppb). Additionally, three metal and three polypropylene supplemental feeders were each filled with 45.4 kg of triple cleaned corn and placed in an open field to study long-term aflatoxin buildup. Feeders were sampled every 3 months from November 2013-November 2014. Average concentration of aflatoxin over the year was 4.08 ± 2.53 ppb (±SE) in metal feeders, and 1.43 ± 0.89 ppb (±SE) in polypropylene feeders. The concentration of aflatoxins is not affected by the type of feeder (metal vs polypropylene), the season corn was sampled, and the location in the feeder (top, middle, bottom) where corn is sampled. It is unlikely that corn used in supplemental feeders is contributing to the bobwhite decline due to the low levels of aflatoxin found in purchased corn and long-term storage of corn used in supplemental feeders.

Cerebrospinal fluid and plasma oxytocin concentrations are positively correlated and negatively predict anxiety in children.

The neuropeptide oxytocin (OXT) exerts anxiolytic and prosocial effects in the central nervous system of rodents. A number of recent studies have attempted to translate these findings by investigating the relationships between peripheral (e.g., blood, urinary and salivary) OXT concentrations and behavioral functioning in humans. Although peripheral samples are easy to obtain in humans, whether peripheral OXT measures are functionally related to central OXT activity remains unclear. To investigate a possible relationship, we quantified OXT concentrations in concomitantly collected cerebrospinal fluid (CSF) and blood samples from child and adult patients undergoing clinically indicated lumbar punctures or other CSF-related procedures. Anxiety scores were obtained in a subset of child participants whose parents completed psychometric assessments. Findings from this study indicate that plasma OXT concentrations significantly and positively predict CSF OXT concentrations (r=0.56, P=0.0064, N=27). Moreover, both plasma (r=-0.92, P=0.0262, N=10) and CSF (r=-0.91, P=0.0335, N=10) OXT concentrations significantly and negatively predicted trait anxiety scores, consistent with the preclinical literature. Importantly, plasma OXT concentrations significantly and positively (r=0.96, P=0.0115, N=10) predicted CSF OXT concentrations in the subset of child participants who provided behavioral data. This study provides the first empirical support for the use of blood measures of OXT as a surrogate for central OXT activity, validated in the context of behavioral functioning. These preliminary findings also suggest that impaired OXT signaling may be a biomarker of anxiety in humans, and a potential target for therapeutic development in individuals with anxiety disorders.

Retrolaminar Migration of Intraocular Silicone Oil.

BACKGROUND: Migration of intravitreal silicone to the retrolaminar optic nerve was detected pathologically in 1983, symptomatic migration to the subarachnoid space of the optic nerve was reported in 1994, and asymptomatic intraventricular silicone was first seen radiographically in 1999. Since then, little advance has been made in understanding this phenomenon despite numerous case reports. Although some authors have restricted their attention to cases of intraventricular silicone, we believe that these represent part of a clinical spectrum and that all cases with retrolaminar silicone should be considered. The pathophysiology of silicone migration may have significant implications for the management of patients after vitrectomy. EVIDENCE ACQUISITION: Two patients were evaluated by the authors. An internet-based literature review was conducted, beginning with the key search terms "intraventricular, intracranial, subarachnoid, or optic nerve silicone," and "complications of vitrectomy or intravitreal silicone." Further searches cascaded from the initial search results. An additional 24 cases of retrolaminar migration of silicone oil were found and summarized. The relevant anatomy and pathophysiology were reviewed, with attention to additional information from enucleation studies, as well as to gaps in the current understanding of this process. RESULTS: Retrolaminar migration of silicone oil may be more common than previously thought, especially in at-risk patient groups, and may be associated with visual and neurologic symptoms. Some impressions regarding the cause and significance of this syndrome seem incorrect. Although this process is likely linked to postoperative elevations of intraocular pressure, the exact mechanisms of silicone entry into the subarachnoid space remain undefined. A number of anatomic factors may influence the movement of silicone from the orbit and in the various compartments of the subarachnoid space and ventricular system, resulting in variability of clinical presentations and radiologic findings. Implications for clinical decision making and directions for further research are discussed. CONCLUSION: Greater awareness on the part of treating physicians, systematic study of at-risk populations, and advances in imaging technology will allow further insight into this phenomenon.