Endonucleolytic RNA cleavage drives changes in gene expression during the innate immune response.

Viral infection triggers several double-stranded RNA (dsRNA) sensors that lead to changes in gene expression in the cell. One of these sensors activates an endonuclease, ribonuclease L (RNase L), that cleaves single-stranded RNA. However, how the resultant widespread RNA fragmentation affects gene expression is not fully understood. Here, we show that this fragmentation induces the ribotoxic stress response via ZAKα, potentially through stalled ribosomes and/or ribosome collisions. The p38 and JNK pathways that are activated as part of this response promote outcomes that inhibit the virus, such as programmed cell death. We also show that RNase L limits the translation of stress-responsive genes. Intriguingly, we found that the activity of the generic endonuclease, RNase A, recapitulates many of the same molecular phenotypes as activated RNase L, demonstrating how widespread RNA cleavage can evoke an antiviral program.

Air pollution, genetic factors, and chronic rhinosinusitis: A prospective study in the UK Biobank.

BACKGROUND: Chronic rhinosinusitis (CRS) is a prevalent upper respiratory condition that manifests in two primary subtypes: CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). While previous studies indicate a correlation between air pollution and CRS, the role of genetic predisposition in this relationship remains largely unexplored. We hypothesized that higher air pollution exposure would lead to the development of CRS, and that genetic susceptibility might modify this association. METHODS: This cohort study involving 367,298 adult participants from the UK Biobank, followed from March 2006 to October 2021. Air pollution metrics were estimated at residential locations using land-use regression models. Cox proportional hazard models were employed to explore the associations between air pollution exposure and CRS, CRSwNP, and CRSsNP. A polygenic risk score (PRS) was constructed to evaluate the joint effect of air pollution and genetic predisposition on the development of CRS. RESULTS: We found that the risk of CRS increased under long-term exposure to PM2.5 [the hazard ratios (HRs) with 95 % CIs: 1.59 (1.26-2.01)], PM10 [1.64 (1.26-2.12)], NO2 [1.11 (1.04-1.17)], and NOx [1.18 (1.12-1.25)], respectively. These effects were more pronounced among participants with CRSwNP, although the differences were not statistically significant. Additionally, we found that the risks for CRS and CRSwNP increased in a graded manner among participants with higher PRS or higher exposure to PM2.5, PM10, or NOx concentrations. However, no multiplicative or additive interactions were observed. CONCLUSIONS: Long-term exposure to air pollution increases the risk of CRS, particularly CRSwNP underscoring the need to prioritize clean air initiatives and environmental regulations.

MHConstructor: A high-throughput, haplotype-informed solution to the MHC assembly challenge.

The extremely high levels of genetic polymorphism within the human major histocompatibility complex (MHC) limit the usefulness of reference-based alignment methods for sequence assembly. We incorporate a short read de novo assembly algorithm into a workflow for novel application to the MHC. MHConstructor is a containerized pipeline designed for high-throughput, haplotype-informed, reproducible assembly of both whole genome sequencing and target-capture short read data in large, population cohorts. To-date, no other self-contained tool exists for the generation of de novo MHC assemblies from short read data. MHConstructor facilitates wide-spread access to high quality, alignment-free MHC sequence analysis.

Unveiling Highly Sensitive Active Site in Atomically Dispersed Gold Catalysts for Enhanced Ethanol Dehydrogenation.

Developing a desirable ethanol dehydrogenation process necessitates a highly efficient and selective catalyst with low cost. Herein, we show that the "complex active site" consisting of atomically dispersed Au atoms with the neighboring oxygen vacancies (Vo) and undercoordinated cation on oxide supports can be prepared and display unique catalytic properties for ethanol dehydrogenation. The "complex active site" Au-Vo-Zr3+ on Au1/ZrO2 exhibits the highest H2 production rate, with above 37,964 mol H2 per mol Au per hour (385 g H2 g-1 Au h-1) at 350 oC, which is 3.32, 2.94 and 15 times higher than Au1/CeO2, Au1/TiO2, and Au1/Al2O3, respectively. Combining experimental and theoretical studies, we demonstrate the structural sensitivity of these complex sites by assessing their selectivity and activity in ethanol dehydrogenation. Our study sheds new light on the design and development of cost-effective and highly efficient catalysts for ethanol dehydrogenation. Fundamentally, atomic-level catalyst design by colocalizing catalytically active metal atoms forming a structure-sensitive "complex site", is a crucial way to advance from heterogeneous catalysis to molecular catalysis. Our study advanced the understanding of the structure sensitivity of the active site in atomically dispersed catalysts.

Evaluating the risk of return to the operating room across all elective orthopaedic procedures.

BACKGROUND: Although elective procedures have life-changing potential, all surgeries come with an inherent risk of reoperation. There is a gap in knowledge investigating the risk of reoperation across orthopaedics. We aimed to identify the elective orthopaedic procedures with the highest rate of unplanned reoperation and the reasons for these procedures having such high reoperation rates. METHODS: Patients in the NSQIP database were identified using CPT and ICD-10 codes. We isolated 612,815 orthopaedics procedures from 2018 to 2020 and identified the 10 CPT codes with the greatest rate of unplanned return to the operating room. For each index procedure, we identified the ICD-10 codes for the reoperation procedure and categorized them into infection, mechanical failure, fracture, wound disruption, hematoma or seroma, nerve pathology, other, and unspecified. RESULTS: Below knee amputation (BKA) (CPT 27880) had the highest reoperation rate of 6.92% (37 of 535 patients). Posterior-approach thoracic (5.86%) or cervical (4.14%) arthrodesis and cervical laminectomy (3.85%), revision total hip arthroplasty (5.23%), conversion to total hip arthroplasty (4.33%), and revision shoulder arthroplasty (4.22%) were among the remaining highest reoperation rates. The overall leading causes of reoperation were infection (30.1%), mechanical failure (21.1%), and hematoma or seroma (9.4%) for the 10 procedures with the highest reoperation rates. CONCLUSIONS: This study successfully identified the elective orthopaedic procedures with the highest 30-day return to OR rates. These include BKA, posterior thoracic and cervical spinal arthrodesis, revision hip arthroplasty, revision total shoulder arthroplasty, and cervical laminectomy. With this data, we can identify areas across orthopaedics in which revising protocols may improve patient outcomes and limit the burden of reoperations on patients and the healthcare system. Future studies should focus on the long-term physical and financial impact that these reoperations may have on patients and hospital systems. LEVEL OF CLINICAL EVIDENCE: IV.

Host tracheal and intestinal microbiomes inhibit Coccidioides growth in vitro.

Coccidioidomycosis, also known as Valley fever, is a disease caused by the fungal pathogen Coccidioides. Unfortunately, patients are often misdiagnosed with bacterial pneumonia, leading to inappropriate antibiotic treatment. The soil Bacillus subtilis-like species exhibits antagonistic properties against Coccidioides in vitro; however, the antagonistic capabilities of host microbiota against Coccidioides are unexplored. We sought to examine the potential of the tracheal and intestinal microbiomes to inhibit the growth of Coccidioides in vitro. We hypothesized that an uninterrupted lawn of microbiota obtained from antibiotic-free mice would inhibit the growth of Coccidioides, while partial in vitro depletion through antibiotic disk diffusion assays would allow a niche for fungal growth. We observed that the microbiota grown on 2×GYE (GYE) and Columbia colistin and nalidixic acid with 5% sheep's blood agar inhibited the growth of Coccidioides, but microbiota grown on chocolate agar did not. Partial depletion of the microbiota through antibiotic disk diffusion revealed diminished inhibition and comparable growth of Coccidioides to controls. To characterize the bacteria grown and identify potential candidates contributing to the inhibition of Coccidioides, 16S rRNA sequencing was performed on tracheal and intestinal agar cultures and murine lung extracts. We found that the host bacteria likely responsible for this inhibition primarily included Lactobacillus and Staphylococcus. The results of this study demonstrate the potential of the host microbiota to inhibit the growth of Coccidioides in vitro and suggest that an altered microbiome through antibiotic treatment could negatively impact effective fungal clearance and allow a niche for fungal growth in vivo. IMPORTANCE: Coccidioidomycosis is caused by a fungal pathogen that invades the host lungs, causing respiratory distress. In 2019, 20,003 cases of Valley fever were reported to the CDC. However, this number likely vastly underrepresents the true number of Valley fever cases, as many go undetected due to poor testing strategies and a lack of diagnostic models. Valley fever is also often misdiagnosed as bacterial pneumonia, resulting in 60%-80% of patients being treated with antibiotics prior to an accurate diagnosis. Misdiagnosis contributes to a growing problem of antibiotic resistance and antibiotic-induced microbiome dysbiosis; the implications for disease outcomes are currently unknown. About 5%-10% of symptomatic Valley fever patients develop chronic pulmonary disease. Valley fever causes a significant financial burden and a reduced quality of life. Little is known regarding what factors contribute to the development of chronic infections and treatments for the disease are limited.

Concordance Between Electronic Health Record-Recorded Race and Ethnicity and Patient Report in Emergency Department Patients.

OBJECTIVE: We assessed the concordance of patient-reported race and ethnicity for emergency department (ED) patients compared with what was recorded in the electronic health record. METHODS: We conducted a single-center, prospective, observational study of 744 ED patients (English- and/or Spanish-speaking), asking them to describe their race and ethnicity. We compared the distributions of ethnicity and race between patient-reported and electronic health record data using McNemar's test. We calculated percent agreement and Cohen's kappa, with 95% confidence intervals (CI), for the concordance of patient-reported race and ethnicity with electronic health record data. RESULTS: Of 744 ED patients, 731 participants who completed the survey reported their ethnicity, resulting in 98.2% of electronic health records obtained ethnicities matched self-reported data (kappa = 0.95; 95% CI: 0.92 to 0.98). For those who self-reported as Hispanic, only 92.3% agreement was observed between the self-reported and electronic health record values. For all patients who had race recorded, 85.4% agreement was observed (kappa = 0.75; 95% CI 0.71 to 0.79). High rates of agreement were observed for Black or African American patients (98.7%) and White patients (96.6%), with low rates for those who identified as "More than one race" (22.9%) or "Other" race (1.8%). In the subset of Hispanic patients, low rates of agreement (25.0%) were observed for race (kappa = 0.10; 95% CI 0.01 to 0.19). CONCLUSIONS: Documentation discordance regarding race and ethnicity exists between electronic health records and self-reported data for our ED patients, particularly for ethnically Hispanic and Latino/a patients. Future efforts should focus on ensuring that demographic information in the electronic health record is accurately collected.

Quality of life in chordoma survivors: results from the Chordoma Foundation Survivorship Survey.

OBJECTIVE: Chordomas are rare malignant bone tumors whose location in the skull base or spine, invasive surgical treatment, and accompanying adjuvant radiotherapy may all lead patients to experience poor quality of life (QOL). Limited research has been conducted on specific demographic and clinical factors associated with decreased QOL in chordoma survivors. Thus, the aim of the present study was to investigate several potential variables and their impact on specific QOL domains in these patients as well the frequencies of specific QOL challenges within these domains. METHODS: The Chordoma Foundation (CF) Survivorship Survey was electronically distributed to chordoma survivors subscribed to the CF Chordoma Connections forum. Survey questions assessed QOL in three domains: physical, emotional/cognitive, and social. The degree of impairment was assessed by grouping the participants into high- and low-challenge groups designated by having ≥ 5 or < 5 symptoms or challenges within a given QOL domain. Bivariate analysis of demographic and clinical characteristics between these groups was conducted using Fisher's exact test and the Mann-Whitney U-test. RESULTS: A total of 665 chordoma survivors at least partially completed the survey. On bivariate analysis, female sex was significantly associated with increased odds of significant emotional (p = 0.001) and social (p = 0.019) QOL burden. Younger survivors (age < 65 years) were significantly more likely to experience significant physical (p < 0.0001), emotional (p < 0.0001), and social (p < 0.0001) QOL burden. Skull base chordoma survivors had significantly higher emotional/cognitive QOL burden than spinal chordoma survivors (p = 0.022), while the converse was true for social QOL challenges (p = 0.0048). Survivors currently in treatment were significantly more likely to experience significant physical QOL challenges compared with survivors who completed their treatment > 10 years ago (p = 0.0074). Fear of cancer recurrence (FCR) was the most commonly reported emotional/cognitive QOL challenge (49.6%). Only 41% of the participants reported having their needs met for their physical QOL challenges as well as 25% for emotional/cognitive and 18% for social. CONCLUSIONS: The authors' findings suggest that younger survivors, female survivors, and survivors currently undergoing treatment for chordoma are at high risk for adverse QOL outcomes. Additionally, although nearly half of the participants reported a FCR, very few reported having adequate emotional/cognitive care. These findings may be useful in identifying specific groups of chordoma survivors vulnerable to QOL challenges and bring to light the need to expand care to meet the QOL needs for these patients.

Validation of the Quality Analysis of Medical Artificial Intelligence (QAMAI) tool: a new tool to assess the quality of health information provided by AI platforms.

BACKGROUND: The widespread diffusion of Artificial Intelligence (AI) platforms is revolutionizing how health-related information is disseminated, thereby highlighting the need for tools to evaluate the quality of such information. This study aimed to propose and validate the Quality Assessment of Medical Artificial Intelligence (QAMAI), a tool specifically designed to assess the quality of health information provided by AI platforms. METHODS: The QAMAI tool has been developed by a panel of experts following guidelines for the development of new questionnaires. A total of 30 responses from ChatGPT4, addressing patient queries, theoretical questions, and clinical head and neck surgery scenarios were assessed by 27 reviewers from 25 academic centers worldwide. Construct validity, internal consistency, inter-rater and test-retest reliability were assessed to validate the tool. RESULTS: The validation was conducted on the basis of 792 assessments for the 30 responses given by ChatGPT4. The results of the exploratory factor analysis revealed a unidimensional structure of the QAMAI with a single factor comprising all the items that explained 51.1% of the variance with factor loadings ranging from 0.449 to 0.856. Overall internal consistency was high (Cronbach's alpha = 0.837). The Interclass Correlation Coefficient was 0.983 (95% CI 0.973-0.991; F (29,542) = 68.3; p < 0.001), indicating excellent reliability. Test-retest reliability analysis revealed a moderate-to-strong correlation with a Pearson's coefficient of 0.876 (95% CI 0.859-0.891; p < 0.001). CONCLUSIONS: The QAMAI tool demonstrated significant reliability and validity in assessing the quality of health information provided by AI platforms. Such a tool might become particularly important/useful for physicians as patients increasingly seek medical information on AI platforms.

Longitudinal analysis within one hospital in sub-Saharan Africa over 20 years reveals repeated replacements of dominant clones of Klebsiella pneumoniae and stresses the importance to include temporal patterns for vaccine design considerations.

BACKGROUND: Infections caused by multidrug-resistant gram-negative bacteria present a severe threat to global public health. The WHO defines drug-resistant Klebsiella pneumoniae as a priority pathogen for which alternative treatments are needed given the limited treatment options and the rapid acquisition of novel resistance mechanisms by this species. Longitudinal descriptions of genomic epidemiology of Klebsiella pneumoniae can inform management strategies but data from sub-Saharan Africa are lacking. METHODS: We present a longitudinal analysis of all invasive K. pneumoniae isolates from a single hospital in Blantyre, Malawi, southern Africa, from 1998 to 2020, combining clinical data with genome sequence analysis of the isolates. RESULTS: We show that after a dramatic increase in the number of infections from 2016 K. pneumoniae becomes hyperendemic, driven by an increase in neonatal infections. Genomic data show repeated waves of clonal expansion of different, often ward-restricted, lineages, suggestive of hospital-associated transmission. We describe temporal trends in resistance and surface antigens, of relevance for vaccine development. CONCLUSIONS: Our data highlight a clear need for new interventions to prevent rather than treat K. pneumoniae infections in our setting. Whilst one option may be a vaccine, the majority of cases could be avoided by an increased focus on and investment in infection prevention and control measures, which would reduce all healthcare-associated infections and not just one.

Managing Modern Antiretroviral Therapy in the Intensive Care Unit: Overcoming Challenges for Critically Ill People With Human Immunodeficiency Virus.

People with human immunodeficiency virus (HIV) have a 50% excess risk for intensive care unit (ICU) admission, often for non-HIV-related conditions. Despite this, clear guidance for managing antiretroviral therapy (ART) in this setting is lacking. Selecting appropriate ART in the ICU is complex due to drug interactions, absorption issues, and dosing adjustments. Continuing ART in the ICU can be challenging due to organ dysfunction, drug interactions, and formulary limitations. However, with careful consideration, continuation is often feasible through dose adjustments or alternative administration methods. Temporary discontinuation of ART may be beneficial depending on the clinical scenario. Clinicians should actively seek resources and support to mitigate adverse events and drug interactions in critically ill people with HIV. Navigating challenges in the ICU can optimize ART and improve care and outcomes for critically ill people with HIV. This review aims to identify strategies for addressing the challenges associated with the use of modern ART in the ICU.

Low-Titer Type O Whole Blood for Transfusing Perinatal Patients after Acute Hemorrhage: A Case Series.

Objective Acute and massive blood loss is fortunately a rare occurrence in perinatal/neonatal practice. When it occurs, typical transfusion paradigms utilize sequential administration of blood components. However, an alternative approach, transfusing type O whole blood with low anti-A and anti-B titers, (LTOWB) has recently been approved and utilized in trauma surgery. Study Design Retrospective analysis of all perinatal patients who have received LTOWB after acute massive hemorrhage at the Intermountain Medical Center. Results LTOWB was the initial transfusion product we used to resuscitate/treat 25 women with acute and massive postpartum hemorrhage and five infants with acute hemorrhage in the first hours/days after birth. We encountered no problems obtaining or transfusing this product and we recognized no adverse effects of this treatment. Conclusion Transfusing LTOWB to perinatal patients after acute blood loss is feasible and appears at least as safe a serial component transfusion. Its use has subsequently been expanded to multiple hospitals in our region as first-line transfusion treatment for acute perinatal hemorrhage. Key Points Low-titer type O whole blood (LTOWB) was our initial transfusion product for 30 perinatal patients with acute hemorrhage. Twenty-five of these were obstetrical patients and five were neonatal patients. We encountered no problems with, or adverse effects from LTOWB in any of these patients. LTOWB transfusions to women were ten days since donor draw (interquartile range, 8-13) and to neonates was six days (5-8).

Improving in vivo assays in snake venom and antivenom research: A community discussion.

On the 26 th January 2023, a free to attend, 'improving in vivo snake venom research: a community discussion' meeting was held virtually. This webinar brought together researchers from around the world to discuss current neutralisation of venom lethality mouse assays that are used globally to assess the efficacy of therapies for snakebite envenoming. The assay's strengths and weaknesses were highlighted, and we discussed what improvements could be made to refine and reduce animal testing, whilst supporting preclinical antivenom and drug discovery for snakebite envenoming. This report summarises the issues highlighted, the discussions held, with additional commentary on key perspectives provided by the authors.

Anti-N-Methyl-D-Aspartate Receptor Encephalopathy in a Young Female.

Widely distributed in the central nervous system (CNS), N-methyl-D-aspartate receptors (NMDARs) are believed to be involved in long-term potentiation, essential in regulating and forming memory. This condition primarily occurs in young females because of autoantibodies forming against the N-methyl-D-aspartate receptor-1 (NR1) or N-methyl-D-aspartate receptor-2 (NR2) subunits of NMDAR in the CNS, ultimately portraying a unique psychoneurological phenomenon. Patients with antibodies against NMDAR present with a combination of neurological and psychiatric signs and symptoms. This article presents a case of a young female with no significant past medical, psychological, or surgical history. While being previously diagnosed with acute psychosis, upon arrival at the emergency department (ED), she also displayed an acute decline in judgment, hallucinations, severe agitation, and peculiar behavior, prompting family members to seek medical attention. Consequently, she was evaluated for metabolic and infectious encephalopathy. Following a thorough examination and extensive laboratory imaging, the patient was found to have NMDAR antibody encephalopathy. After dedicated treatment, her two-month follow-up presented a complete resolution of symptoms.

Failure Following Revision Total Hip Arthroplasty after Cobalt-Chrome Femoral Heads are Placed on a Retained Femoral Stem.

BACKGROUND: Failure due to trunnionosis with adverse local tissue reaction (ALTR) has been reported with cobalt-chrome (CoCr) heads in total hip arthroplasty (THA); however, there is limited data on the use of these heads in the revision setting. The purpose of this study was to analyze the outcomes of patients who underwent revision THA with a retained femoral component and received a CoCr femoral head on a used trunnion. METHODS: In this retrospective review, we identified all patients who underwent revision THA with a retained femoral component and received a CoCr femoral head between February 2006 and March 2014. Demographic factors, implant details, and post-operative complications, including the need for repeat revisions, were recorded. In total, 107 patients were included (mean age 67 years, 74.0% women). Of the 107 patients, 24 (22.4%) required repeat revisions. RESULTS: Patients who required repeat revision were younger than those who did not (mean age: 62.9 versus 69, P = 0.03). The most common indications for repeat revision were instability (8 of 24, 33.3%), ALTR (5 of 24, 20.8%), and infection (4 of 18, 16.7%). Evidence of ALTR or metallosis was identified at the time of reoperation in 10 of the 24 patients who underwent re-revision (41.7%). CONCLUSION: The placement of a new CoCr femoral head on a used trunnion during revision THA with a retained femoral component carries a significant risk of complication (22.4%) and should be avoided when possible.

Two-Step Conversion of Metal and Metal Oxide Precursor Films to 2D Transition Metal Dichalcogenides and Heterostructures.

The widely studied class of two-dimensional (2D) materials known as transition metal dichalcogenides (TMDs) are now well-poised to be employed in real-world applications ranging from electronic logic and memory devices to gas and biological sensors. Several scalable thin film synthesis techniques have demonstrated nanoscale control of TMD material thickness, morphology, structure, and chemistry and correlated these properties with high-performing, application-specific device metrics. In this review, the particularly versatile two-step conversion (2SC) method of TMD film synthesis is highlighted. The 2SC technique relies on deposition of a solid metal or metal oxide precursor material, followed by a reaction with a chalcogen vapor at an elevated temperature, converting the precursor film to a crystalline TMD. Herein, the variables at each step of the 2SC process including the impact of the precursor film material and deposition technique, the influence of gas composition and temperature during conversion, as well as other factors controlling high-quality 2D TMD synthesis are considered. The specific advantages of the 2SC approach including deposition on diverse substrates, low-temperature processing, orientation control, and heterostructure synthesis, among others, are featured. Finally, emergent opportunities that take advantage of the 2SC approach are discussed to include next-generation electronics, sensing, and optoelectronic devices, as well as catalysis for energy-related applications.

Dynamic internal jugular vein venography: a descriptive study in 89 patients with suspected cerebral venous outflow disorders.

BACKGROUND: Internal jugular vein (IJV) stenosis has recently been recognized as a plausible source of symptom etiology in patients with cerebral venous outflow disorders (CVD). Diagnosis and determining surgical candidacy remains difficult due to a poor understanding of IJV physiology and positional symptom exacerbation often reported by these patients. METHODS: A retrospective single-center chart review was conducted on adult patients who underwent diagnostic cerebral venography with rotational IJ venography from 2022 to 2024. Patients were divided into three groups for further analysis based on symptoms and diagnostic criteria: presumed jugular stenosis, near-healthy venous outflow, and idiopathic intracranial hypertension. RESULTS: Eighty-nine patients were included in the study. Most commonly, ipsilateral rotation resulted in ipsilateral IJV stenosis and gradient development at C4-6 and contralateral stenosis and gradient appearance in the contralateral IJV at C1, with stenosis and gradient development in bilateral IJVs at C1-3 bilaterally during chin flexion. In all patients, 93.3% developed at least moderate dynamic stenosis of at least one IJV, more than two-thirds (69.7%) developed either severe or occlusive stenosis during rightward and leftward rotation, and 81.8% developed severe or occlusive stenosis with head flexion. Dynamic gradients of at least 4 mmHg were seen in 68.5% of patients, with gradients of at least 8 mmHg in 31.5% and at least 10 mmHg in 12.4%. CONCLUSION: This study is the first to document dynamic changes in IJV caliber and gradients in different head positions, offering insights into the complex nature of venous outflow and its impact on CVD.

A role of dentate gyrus mechanistic target of rapamycin activation in epileptogenesis in a mouse model of posttraumatic epilepsy.

OBJECTIVE: The mechanistic target of rapamycin (mTOR) pathway has been implicated in promoting epileptogenesis in animal models of acquired epilepsy, such as posttraumatic epilepsy (PTE) following traumatic brain injury (TBI). However, the specific anatomical regions and neuronal populations mediating mTOR's role in epileptogenesis are not well defined. In this study, we tested the hypothesis that mTOR activation in dentate gyrus granule cells promotes neuronal death, mossy fiber sprouting, and PTE in the controlled cortical impact (CCI) model of TBI. METHODS: An adeno-associated virus (AAV)-Cre viral vector was injected into the hippocampus of Rptorflox/flox (regulatory-associated protein of mTOR) mutant mice to inhibit mTOR activation in dentate gyrus granule cells. Four weeks after AAV-Cre or AAV-vehicle injection, mice underwent CCI injury and were subsequently assessed for mTOR pathway activation by Western blotting, neuronal death, and mossy fiber sprouting by immunopathological analysis, and posttraumatic seizures by video-electroencephalographic monitoring. RESULTS: AAV-Cre injection primarily affected the dentate gyrus and inhibited hippocampal mTOR activation following CCI injury. AAV-Cre-injected mice had reduced neuronal death in dentate gyrus detected by Fluoro-Jade B staining and decreased mossy fiber sprouting by ZnT3 immunostaining. Finally, AAV-Cre-injected mice exhibited a decrease in incidence of PTE. SIGNIFICANCE: mTOR pathway activation in dentate gyrus granule cells may at least partly mediate pathological abnormalities and epileptogenesis in models of TBI and PTE. Targeted modulation of mTOR activity in this hippocampal network may represent a focused therapeutic approach for antiepileptogenesis and prevention of PTE.

Structure and mechanism of biosynthesis of Streptococcus mutans cell wall polysaccharide.

Streptococcus mutans, the causative agent of human dental caries, expresses a cell wall attached Serotype c- specific Carbohydrate (SCC) that is critical for cell viability. SCC consists of a repeating →3)α-Rha(1→2)α-Rha(1→ polyrhamnose backbone, with glucose (Glc) side-chains and glycerol phosphate (GroP) decorations. This study reveals that SCC has one major and two minor Glc modifications. The major Glc modification, α-Glc, attached to position 2 of 3-rhamnose, is installed by SccN and SccM glycosyltransferases and is the site of the GroP addition. The minor Glc modifications are ß-Glc linked to position 4 of 3-rhamnose installed by SccP and SccQ glycosyltransferases, and α-Glc attached to position 4 of 2-rhamnose installed by SccN working in tandem with an unknown enzyme. Both the major and the minor ß-Glc modifications control bacterial morphology, but only the GroP and major Glc modifications are critical for biofilm formation.