Evidence of Disrupted-in Schizophrenia 1 (DISC1) as an arsenic binding protein and implications regarding its role as a translational activator.

Disrupted-in-schizophrenia-1 (DISC1) is a scaffold protein that plays a pivotal role in orchestrating signaling pathways involved in neurodevelopment, neural migration, and synaptogenesis. Among those, it has recently been reported that the role DISC1 in the Akt/mTOR pathway can shift from a global translational repressor to a translational activator in response to oxidative stress induced by arsenic. In this study we are providing evidence that DISC1 can directly bind arsenic via a C-terminal cysteine motif (C-X-C-X-C). A series of fluorescence-based binding assays were conducted with a truncated C-terminal domain construct of DISC1 and a of series of single, double, and triple cysteine mutants. We found that arsenous acid, a trivalent arsenic derivative, specifically binds to the C-terminal cysteine motif of DISC1 with low micromolar affinity. All three cysteines of the motif are required for high-affinity binding. Electron microscopy experiments combined with in silico structural predictions revealed that that the C-terminal of DISC1 forms an elongated tetrameric complex. The cysteine motif is consistently predicted to be located within a loop, fully exposed to solvent, providing a simple molecular framework to explain the high-affinity of DISC1 toward arsenous acid. This study sheds light on a novel functional facet of DISC1 as an arsenic binding protein and highlights its potential role as both a sensor and translational modulator within the Akt/mTOR pathway.

Dual factors required for cytochrome-P450-mediated hydrocarbon ring contraction in bacterial gibberellin phytohormone biosynthesis.

Cytochromes P450 (CYPs) are heme-thiolate monooxygenases that prototypically catalyze the insertion of oxygen into unactivated C-H bonds but are capable of mediating more complex reactions. One of the most remarked-upon alternative reactions occurs during biosynthesis of the gibberellin A (GA) phytohormones, involving hydrocarbon ring contraction with coupled aldehyde extrusion of ent-kaurenoic acid to form the first gibberellin intermediate. While the unusual nature of this reaction has long been noted, its mechanistic basis has remained opaque. Building on identification of the relevant CYP114 from bacterial GA biosynthesis, detailed structure-function studies are reported here, including development of in vitro assays as well as crystallographic analyses both in the absence and presence of substrate. These structures provided insight into enzymatic catalysis of this unusual reaction, as exemplified by identification of a key role for the "missing" acid from an otherwise highly conserved acid-alcohol pair of residues. Notably, the results demonstrate that ring contraction requires dual factors, both the use of a dedicated ferredoxin and absence of the otherwise conserved acidic residue, with exclusion of either limiting turnover to just the initiating and more straightforward hydroxylation. The results provide detailed insight into the enzymatic structure-function relationships underlying this fascinating reaction and support the use of a semipinacol mechanism for the unusual ring contraction reaction.

Evidence of DISC1 as an arsenic binding protein and implications regarding its role as a translational activator.

Disrupted-in-schizophrenia-1 (DISC1) is a scaffolding protein that plays a pivotal role in orchestrating signaling pathways involved in neurodevelopment, neural migration, and synaptogenesis. Among those, it has recently been reported that the role of DISC1 in the Akt/mTOR pathway can shift from a global translational repressor to a translational activator in response to oxidative stress induced by arsenic. In this study we provide evidence that DISC1 can directly bind arsenic via a C-terminal cysteine motif (C-X-C-X-C). A series of fluorescence-based binding assays were conducted with a truncated C-terminal domain construct of DISC1 and a series of single, double, and triple cysteine mutants. We found that arsenous acid, a trivalent arsenic derivative, specifically binds to the C-terminal cysteine motif of DISC1 with low micromolar affinity. All three cysteines of the motif are required for high-affinity binding. Electron microscopy experiments combined with in silico structural predictions reveal that the C-terminal of DISC1 forms an elongated tetrameric complex. The cysteine motif is consistently predicted to be located within a loop, fully exposed to solvent, providing a simple molecular framework to explain the high-affinity of DISC1 toward arsenous acid. This study sheds light on a novel functional facet of DISC1 as an arsenic binding protein and highlights its potential role as both a sensor and translational modulator within Akt/mTOR pathway.

Hybrid Thermophilic/Mesophilic Enzymes Reveal a Role for Conformational Disorder in Regulation of Bacterial Enzyme I.

Conformational disorder is emerging as an important feature of biopolymers, regulating a vast array of cellular functions, including signaling, phase separation, and enzyme catalysis. Here we combine NMR, crystallography, computer simulations, protein engineering, and functional assays to investigate the role played by conformational heterogeneity in determining the activity of the C-terminal domain of bacterial Enzyme I (EIC). In particular, we design chimeric proteins by hybridizing EIC from thermophilic and mesophilic organisms, and we characterize the resulting constructs for structure, dynamics, and biological function. We show that EIC exists as a mixture of active and inactive conformations and that functional regulation is achieved by tuning the thermodynamic balance between active and inactive states. Interestingly, we also present a hybrid thermophilic/mesophilic enzyme that is thermostable and more active than the wild-type thermophilic enzyme, suggesting that hybridizing thermophilic and mesophilic proteins is a valid strategy to engineer thermostable enzymes with significant low-temperature activity.

Basic-level emergency medical technician administration of fluids and glucose via enzyme-assisted subcutaneous infusion access.

INTRODUCTION: During disasters and mass-casualty incidents (MCIs), there may be insufficient numbers of advanced life support (ALS) providers to provide intravenous (IV) access to all patients requiring parenteral fluids and/or medications. Enzyme-assisted subcutaneous infusion (EASI) access, in which human recombinant hyaluronidase (HRH) augments subcutaneous fluid dispersion and absorption, may be useful when ALS resources are insufficient to meet intravascular access needs. The utility of the use of the EASI lies, in part, in its ease of placement by ALS personnel. OBJECTIVES: The objectives of this study were to document the feasibility, comfort, and speed/degree of infused-glucose uptake through EASI lines placed by basic-level emergency medical technicians (EMT-Bs). METHODS: Eighteen EMT-Bs instituted EASI access on each other. A total of 150 units (1 mL) of HRH were administered through the EASI line, followed by the administration of 250 mL of tracer-labeled D5W. Timed phlebotomy enabled gas chromatography/mass spectrometry characterization of glucose uptake. Enzyme-assisted subcutaneous infusion placement and comfort ratings were tracked and analyzed using non-parametric statistics and Fisher's Exact Test. RESULTS: In all 18 subjects, EASI access required only one attempt and was rated by the EMT-Bs as easy to accomplish. Glucose was absorbed quickly (within five minutes) in all subjects. The rate of infusion was rapid (median 393 mL/hour) and was comfortable for the recipients (median pain score 1/10). CONCLUSIONS: The use of EASI may be viable as a fast, simple, and reliable method for the administration of fluid and glucose by EMT-Bs.

Tulsa oklahoma oktoberfest tent collapse report.

Background. On October 17, 2007, a severe weather event collapsed two large tents and several smaller tents causing 23 injuries requiring evacuation to emergency departments in Tulsa, OK. Methods. This paper is a retrospective analysis of the regional health system's response to this event. Data from the Tulsa Fire Department, The Emergency Medical Services Authority (EMSA), receiving hospitals and coordinating services were reviewed and analyzed. EMS patient care reports were reviewed and analyzed using triage designators assigned in the field, injury severity scores, and critical mortality. Results. EMT's and paramedics from Tulsa Fire Department and EMSA provided care at the scene under unified incident command. Of the 23 patients transported by EMS, four were hospitalized, one with critical spinal injury and one with critical head injury. One patient is still in ongoing rehabilitation. Discussion. Analysis of the 2007 Tulsa Oktoberfest mass casualty incident revealed rapid police/fire/EMS response despite challenges of operations at dark under severe weather conditions and the need to treat a significant number of injured victims. There were no fatalities. Of the patients transported by EMS, a minority sustained critical injuries, with most sustaining injuries amenable to discharge after emergency department care.

Use of electronic brachytherapy to deliver postsurgical adjuvant radiation therapy for endometrial cancer: a retrospective multicenter study.

BACKGROUND: This retrospective, multicenter study evaluated the feasibility and safety of high-dose rate electronic brachytherapy (EBT) as a postsurgical adjuvant radiation therapy for endometrial cancer. METHODS: Medical records were reviewed from 41 patients (age 40-89 years) with endometrial cancer (Federation of International Gynecology and Obstetrics stages IA-IIIC) treated at nine centers between April 2008 and October 2009. Treatment included intracavitary vaginal EBT alone (n = l6) at doses of 18.0-24.0 Gy in 3-4 fractions and EBT in combination with external beam radiation therapy (EBRT, n = 25) at a total radiation dose range of 40.0-80.4 Gy. Doses were prescribed to a depth of 5 mm from the applicator surface and to the upper third (n = 15) and the upper half (n = 26) of the vagina. RESULTS: Median follow-up was 3.8 (range 0.5-12.0) months. All 41 patients received the intended dose of radiation as prescribed. Adverse events occurred in 13 of 41 patients and were mild to moderate (Grade 1-2), consisting primarily of vaginal mucositis, rectal mucosal irritation and discomfort, and temporary dysuria and diarrhea. There were no Grade 3 adverse events in the EBT-only treatment group. One patient, who was being treated with the combination of EBT and EBRT for recurrent endometrial cancer, had a Grade 3 adverse event. No recurrences have been reported to date. CONCLUSION: Electronic brachytherapy provides a feasible treatment option for postoperative adjuvant vaginal brachytherapy as sole radiation therapy and in combination with EBRT for primary endometrial cancer. Early and late toxicities were mild to moderate.

Application of mitomycin-C for head and neck keloids.

Keloids of the head and neck are a relatively common entity in darker-skinned races, occurring in 5%-15% of skin wounds. Keloids are fibrotic lesions that are a result of an abnormal wound-healing process that lacks control of the mechanisms that regulate tissue repair and regeneration. The proliferation of normal tissue-healing processes results in scarring that enlarges well beyond the original wound margins. Many treatment modalities for keloids have been tried with variable amounts of success. Surgical excision, compressive therapy, silicon dressings, corticosteroid injections, radiation, cryotherapy, interferon therapy, and laser therapy have all been used alone or in combination. Despite this wide range of available treatments, recurrence rates typically remain in the 50%-70% range. In this study, we present our results in a series of 10 patients who were treated with surgical excision of head and neck keloids and the application of topical mitomycin-C. Mitomycin-C is a chemotherapeutic agent that inhibits DNA synthesis and fibroblast proliferation. It has been used in ophthalmologic procedures and airway surgery to decrease scar formation. In these 10 patients, we combined surgical excision of keloids with the application of topical mitomycin-C. The patients were then followed postoperatively for recurrence (range, 7-14 months). We have found topical application of mitomycin-C to be an effective therapy for prevention of keloid recurrence in the head and neck, with a success rate of 90% as reported in this series.

Fluoroquinolone-induced arthralgia and myalgia in the treatment of sinusitis.

BACKGROUND: Because of their broad-spectrum coverage, fluoroquinolone antibiotics are widely used in the treatment of acute sinusitis and acute exacerbations of chronic sinusitis. Generally, they are well tolerated, and adverse effects are usually mild. In our experience with quinolones, patients have frequently complained of arthralgias and/or myalgias. Although tendon rupture has been described as one of the more severe side effects, there are few published reports of arthralgias and/or myalgias associated with these drugs. METHODS: A retrospective review of fluoroquinolone prescriptions in a tertiary rhinology clinic was completed. Patients treated with oral levofloxacin for sinusitis over a 12-month period were contacted by mail and asked to complete an anonymous survey regarding adverse effects. Of 81 patients identified, 36 responses were received. RESULTS: Among respondents, the incidence of arthralgias and/or myalgias was 25%, which was more than twice the incidence of any other adverse effect reported. Occurrence of arthralgias and/or myalgias did not appear to be influenced by respondent age, course length, concurrent use of oral steroids, or a history of arthritis. Among those reporting arthralgia or myalgia, symptoms began after an average of 3 days of therapy and resolved an average of 7.5 days after cessation of treatment. Fourteen percent of respondents were unable to complete their course of therapy because of arthralgias and/or myalgias. CONCLUSION: Although effective and generally well tolerated in the treatment of sinusitis, fluoroquinolone antibiotics may produce adverse effects of arthralgia and/or myalgia.

Fortuitous detection of pseudoaneurysm by three-phase bone scan.

We report the diagnosis of an unsuspected pseudoaneurysm in the lower extremity when 3-phase bone scan was used to evaluate a presumed malignancy. We confirmed the diagnosis with duplex ultrasonography and angiography. Although the primary diagnostic modality for detection of pseudoaneurysm remains duplex sonography, the nuclear medicine practitioner should be vigilant for characteristic presentation of a pseudoaneurysm on a 3-phase bone scan, an area of increased radiotracer activity on blood-flow and blood-pool images that becomes a photopenic area on delayed images. This also underscores the need to consider benign vascular lesions in the differential diagnosis of abnormal 3-phase bone scans for presumed tumors.

Recognizing imminent danger: characteristics of a suicide bomber.

By all reports, the public is at increasing risk of attack by terrorist organizations. Citizens have been asked to increase their vigilance and report suspicious individuals to reduce the chance of a suicide or homicide bombing. Terrorist groups often target their actions to inflict the most casualties and may choose mass gatherings to detonate an explosive device. Since EMS providers are frequently assigned to work special details where large numbers of people may gather, EMTs and paramedics can assist law enforcement in identifying individuals who may pose a threat to the people gathered at the event. The characteristics of suicide bombers discussed here are meant to increase your awareness level to recognize a potential problem. The astute EMS provider can then notify appropriate law enforcement personnel for further investigation and action.

Emergency management of cardiac injuries.

Cardiac trauma is not usually treatable in the field. EMS providers must recognize the possibility of cardiac trauma rapidly and evacuate the patient to an appropriate facility. Most therapy for cardiac trauma requires an operating room, preferably with cardiopulmonary bypass capability. Basic patient care should occur en route to the treatment facility. Ensure that the airway is intact, control respirations and bleeding, and restore circulatory volume to a pressure of about 100 systolic. Advanced providers should re-expand any associated tension pneumothorax and ensure the chest wall is stable. Consider early intubation, since operative intervention is likely.