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Chromoblastomycosis treated with posaconazole and adjunctive imiquimod: lending innate immunity a helping hand. Open Forum Infect Dis 2023; 10:ofad124. [PMID: 37035498 PMCID: PMC10077821 DOI: 10.1093/ofid/ofad124] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 03/13/2023] [Indexed: 03/16/2023] Open
Abstract
Abstract
Chromoblastomycosis (CBM) is a difficult-to-treat, chronic fungal infection of the skin and subcutaneous tissue. The evidence base for treatment is scarce, with no standardised therapeutic approach. Chronicity of CBM infection is postulated to be due in part to a failure of host cell-mediated immunity to generate a proinflammatory response sufficient for fungal clearance. We present a case of a chronic chromoblastomycosis lesion of the hand present for nearly four decades, previously refractory to itraconazole monotherapy, that was successfully treated with a combination of posaconazole and adjunctive immunotherapy with topical Imiquimod, a toll-like receptor 7 agonist. Serial biopsies and images demonstrate the clinical and histopathological improvement of the lesion. Randomised trials of antifungal therapy with adjunctive imiquimod are warranted to determine whether a combination of antifungal and host-directed therapy improves outcomes for this neglected tropical mycosis.
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A multisite evaluation of antifungal use in critical care: implications for antifungal stewardship. JAC Antimicrob Resist 2022; 4:dlac055. [PMID: 35756574 PMCID: PMC9217759 DOI: 10.1093/jacamr/dlac055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 04/28/2022] [Indexed: 12/02/2022] Open
Abstract
Background ICUs are settings of high antifungal consumption. There are few data on prescribing practices in ICUs to guide antifungal stewardship implementation in this setting. Methods An antifungal therapy (AFT) service evaluation (15 May-19 November 2019) across ICUs at three London hospitals, evaluating consumption, prescribing rationale, post-prescription review, de-escalation and final invasive fungal infection (IFI) diagnostic classification. Results Overall, 6.4% of ICU admissions (305/4781) received AFT, accounting for 11.41 days of therapy/100 occupied bed days (DOT/100 OBD). The dominant prescribing mode was empirical (41% of consumption), followed by targeted (22%), prophylaxis (18%), pre-emptive (12%) and non-invasive (7%). Echinocandins were the most commonly prescribed drug class (4.59 DOT/100 OBD). In total, 217 patients received AFT for suspected or confirmed IFI; 12%, 10% and 23% were classified as possible, probable or proven IFI, respectively. Hence, in 55%, IFI was unlikely. Proven IFI (n = 50) was mostly invasive candidiasis (92%), of which 48% had been initiated on AFT empirically before yeast identification. Where on-site (1 → 3)-β-d-glucan (BDG) testing was available (1 day turnaround), in those with suspected but unproven invasive candidiasis, median (IQR) AFT duration was 10 (7-15) days with a positive BDG (≥80 pg/mL) versus 8 (5-9) days with a negative BDG (<80 pg/mL). Post-prescription review occurred in 79% of prescribing episodes (median time to review 1 [0-3] day). Where suspected IFI was not confirmed, 38% episodes were stopped and 4% de-escalated within 5 days. Conclusions Achieving a better balance between promptly treating IFI patients and avoiding inappropriate antifungal prescribing in the ICU requires timely post-prescription review by specialist multidisciplinary teams and improved, evidence-based-risk prescribing strategies incorporating rapid diagnostics to guide AFT start and stop decisions.
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The effect of sheep genetic merit and feed allowance on nitrogen partitioning and isotopic discrimination. Animal 2021; 15:100400. [PMID: 34768171 DOI: 10.1016/j.animal.2021.100400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 09/29/2021] [Accepted: 10/04/2021] [Indexed: 10/19/2022] Open
Abstract
Animal nitrogen (N) partitioning is a key parameter for profitability and sustainability of ruminant production systems, which may be predicted from N isotopic discrimination or fractionation (Δ15N). Both animal genetics and feeding level may interact and impact on N partitioning. Therefore, this study aimed to assess the interactive effects of genetic merit (G) and feed allowance (F) on N partitioning and Δ15N in sheep. The sheep were drawn from two levels of G (high G vs. low G; based on New Zealand Sheep Improvement Limited (http://www.sil.co.nz/) dual (wool and meat) growth index) and allocated to two levels of F (1.7 (high F) vs. 1.1 (low F) times Metabolisable Energy requirement for maintenance) treatments. Twenty-four Coopworth rams were divided into four equal groups for a N balance study: high G × high F, high G × low F, low G × high F, and low G × low F. The main factors (G and F) and the interaction term were used for 2-way ANOVA and regression analysis. Higher F led to higher N excretions (urinary N (UN); faecal N (FN); manure N), retained N, N use efficiency (NUE), and urinary purine derivatives excretion (P < 0.05). On the other hand, higher UN/N intake, and plasma Δ15N were observed with the lower F (P < 0.05). Higher G led to increased UN, FN, manure N, apparent N digestibility, and urinary purine derivatives excretion (P < 0.05). Higher F only increased UN in high G sheep, with no effect on low G sheep (P < 0.05). Regression analysis results demonstrated potential to use plasma Δ15N to reflect the effects of G and F on NUE and UN/N intake. Further research is urged to study interactive effects of genetic and feeding level on sheep N partitioning.
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Updates in infection risk and management in acute leukemia. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2020; 2020:135-139. [PMID: 33275701 PMCID: PMC7727589 DOI: 10.1182/hematology.2020000098] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Patients with hematologic malignancies are at increased risk of infection, with associated morbidity and mortality. Patients with acute myeloid leukemia (AML) have qualitative and quantitative deficits in granulocytes predisposing to bacterial and fungal infections. Acute lymphoblastic leukemia results in qualitative deficits in lymphocytes, resulting in hypogammaglobulinemia and reduced cell-mediated immunity predisposing to certain bacterial and viral as well as fungal infections. Chemotherapeutic regimens often compound these deficits, result in prolonged periods of severe neutropenia, and disrupt mucosal barriers, further elevating infection risk. Despite advances in antimicrobial therapies and prophylaxis, acute leukemia patients with disease- and treatment-related immunosuppression remain at risk for life-threatening infection, including with resistant organisms, antimicrobial-related adverse events, and higher treatment costs. Additionally, our knowledge of infection risk and drug-drug interactions with new immune-targeted cancer therapeutics is evolving. Here, we review 3 areas in which standard practice is evolving as challenges arise and new experience is gained, including antibiotic use in febrile neutropenia, fungal prophylaxis, and use of targeted therapies.
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Invasive candidiasis in critical care: challenges and future directions. Intensive Care Med 2020; 46:2001-2014. [PMID: 32990778 DOI: 10.1007/s00134-020-06240-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 09/01/2020] [Indexed: 12/19/2022]
Abstract
Invasive candidiasis is the most common critical care-associated fungal infection with a crude mortality of ~ 40-55%. Important factors contributing to risk of invasive candidiasis in ICU include use of broad-spectrum antimicrobials, immunosuppressive drugs, and total parenteral nutrition alongside iatrogenic interventions which breach natural barriers to infection [vascular catheters, renal replacement therapy, extracorporeal membrane oxygenation (ECMO), surgery]. This review discusses three key challenges in this field. The first is the shift in Candida epidemiology across the globe to more resistant non-albicans species, in particular, the emergence of multi-resistant Candida glabrata and Candida auris, which pose significant treatment and infection control challenges in critical care. The second challenge lies in the timely and appropriate initiation and discontinuation of antifungal therapy. Early antifungal strategies (prophylaxis, empirical and pre-emptive) using tools such as the Candida colonisation index, clinical prediction rules and fungal non-culture-based tests have been developed: we review the evidence on implementation of these tools in critical care to aid clinical decision-making around the prescribing and cessation of antifungal therapy. The third challenge is selection of the most appropriate antifungal to use in critical care patients. While guidelines exist to aid choice, this heterogenous and complex patient group require a more tailored approach, particularly in cases of acute kidney injury, liver impairment and for patients supported by extracorporeal membrane oxygenation. We highlight key research priorities to overcome these challenges in the future.
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Liveweight gain and urinary nitrogen excretion of dairy heifers grazing perennial ryegrass-white clover pasture, canola, and wheat. ANIMAL PRODUCTION SCIENCE 2018. [DOI: 10.1071/an15533] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study was carried out to examine liveweight gain (LWG), urinary nitrogen (N) concentration, and urinary N excretion of dairy heifers grazing perennial ryegrass-white clover pasture, dual-purpose wheat and dual-purpose canola. A temporal replicate design with two replicates was used to conduct the study. A total of 24–30 Friesian × Jersey heifers, aged 9–11 months were allocated into three dietary treatment groups (pasture, canola, and wheat) according to their initial LW (184 ± 7.0 kg; mean ± s.d.) and breeding worth (NZ$142 ± 11.3; mean ± s.d.). Feed was allocated every 4 days with allowance calculated according to feed requirement for maintenance plus 0.8 kg LWG/day. The LWG over the 26–28-day experimental period was higher (P < 0.001) for heifers grazing wheat (0.66 kg/day) and canola (0.53 kg/day) than pasture (0.35 kg/day). After the experimental period, heifers were grazed together in one herd on pasture. The LWG over the 28–44-day carryover period was higher (P < 0.001) in canola (0.86 kg/day) than wheat (0.57 kg/day) and pasture (0.61 kg/day). The concentration of urinary N was lower (P = 0.017) in canola (0.21%) and wheat (0.24%) than pasture (0.35%). Estimated urinary N excretion was lower (P < 0.001) in canola (52.5 g/day) and wheat (59.1 g/day) than pasture (98.9 g/day). Data suggest that grazing canola and wheat compared with pasture may improve heifer LWG and potentially reduce N losses to the environment by reducing the N loading of urine patches.
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EFFECT OF CHRONIC POLYPHARMACY AND THE DRUG BURDEN INDEX (DBI) ON PHYSICAL FUNCTION IN AGED MICE. Innov Aging 2017. [DOI: 10.1093/geroni/igx004.3216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Progressive respiratory depression and bulbar palsy: Answer. J Clin Neurosci 2016. [DOI: 10.1016/j.jocn.2016.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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10
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Physically Fit Soldiers Eat Healthier and Feel Nutrition Impacts Physical Performance. J Acad Nutr Diet 2016. [DOI: 10.1016/j.jand.2016.06.091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Healthy Eating Index Increased after Tactical Human Optimization, Rapid Rehabilitation and Reconditioning (THOR3) Dining Facility Menu Enhancement in Military Operators. J Acad Nutr Diet 2016. [DOI: 10.1016/j.jand.2016.06.181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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12
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Fever, Cough, and Right Lower Quadrant Abdominal Pain in a Liver Transplant Recipient. Am J Transplant 2016. [DOI: 10.1111/ajt.13772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Formation of a carbapenemase resistance detection algorithm for use in the routine laboratory. Br J Biomed Sci 2016; 72:12-22. [DOI: 10.1080/09674845.2015.11666790] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Investigation into the Importance of genes encoding ciliary proteins in congenital heart disease using whole exome sequencing. Cilia 2015. [PMCID: PMC4518900 DOI: 10.1186/2046-2530-4-s1-p9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Discovery of 1-(3,3-dimethylbutyl)-3-(2-fluoro-4-methyl-5-(7-methyl-2-(methylamino)pyrido[2,3-d]pyrimidin-6-yl)phenyl)urea (LY3009120) as a pan-RAF inhibitor with minimal paradoxical activation and activity against BRAF or RAS mutant tumor cells. J Med Chem 2015; 58:4165-79. [PMID: 25965804 DOI: 10.1021/acs.jmedchem.5b00067] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The RAS-RAF-MEK-MAPK cascade is an essential signaling pathway, with activation typically mediated through cell surface receptors. The kinase inhibitors vemurafenib and dabrafenib, which target oncogenic BRAF V600E, have shown significant clinical efficacy in melanoma patients harboring this mutation. Because of paradoxical pathway activation, both agents were demonstrated to promote growth and metastasis of tumor cells with RAS mutations in preclinical models and are contraindicated for treatment of cancer patients with BRAF WT background, including patients with KRAS or NRAS mutations. In order to eliminate the issues associated with paradoxical MAPK pathway activation and to provide therapeutic benefit to patients with RAS mutant cancers, we sought to identify a compound not only active against BRAF V600E but also wild type BRAF and CRAF. On the basis of its superior in vitro and in vivo profile, compound 13 was selected for further development and is currently being evaluated in phase I clinical studies.
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Cysteine specific targeting of the functionally distinct peroxiredoxin and glutaredoxin proteins by the investigational disulfide BNP7787. Molecules 2015; 20:4928-50. [PMID: 25793542 PMCID: PMC6272748 DOI: 10.3390/molecules20034928] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 03/05/2015] [Indexed: 10/25/2022] Open
Abstract
Glutaredoxin (Grx), peroxiredoxin (Prx), and thioredoxin (Trx) are redoxin family proteins that catalyze different types of chemical reactions that impact cell growth and survival through functionally distinct intracellular pathways. Much research is focused on understanding the roles of these redoxin proteins in the development and/or progression of human diseases. Grx and Prx are overexpressed in human cancers, including human lung cancers. BNP7787 is a novel investigational agent that has been evaluated in previous clinical studies, including non-small cell lung cancer (NSCLC) studies. Herein, data from activity assays, mass spectrometry analyses, and X-ray crystallographic studies indicate that BNP7787 forms mixed disulfides with select cysteine residues on Grx and Prx and modulates their function. Studies of interactions between BNP7787 and Trx have been conducted and reported separately. Despite the fact that Trx, Grx, and Prx are functionally distinct proteins that impact oxidative stress, cell proliferation and disease processes through different intracellular pathways, BNP7787 can modify each protein and appears to modulate function through mechanisms that are unique to each target protein. Tumor cells are often genomically heterogeneous containing subpopulations of cancer cells that often express different tumor-promoting proteins or that have multiple dysregulated signaling pathways modulating cell proliferation and drug resistance. A multi-targeted agent that simultaneously modulates activity of proteins important in mediating cell proliferation by functionally distinct intracellular pathways could have many potentially useful therapeutic applications.
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Novel covalent modification of human anaplastic lymphoma kinase (ALK) and potentiation of crizotinib-mediated inhibition of ALK activity by BNP7787. Onco Targets Ther 2015; 8:375-83. [PMID: 25678804 PMCID: PMC4324543 DOI: 10.2147/ott.s73690] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
BNP7787 (Tavocept, disodium 2,2′-dithio-bis-ethanesulfonate) is a novel, investigational, water-soluble disulfide that is well-tolerated and nontoxic. In separate randomized multicenter Phase II and Phase III clinical trials in non-small-cell lung cancer (NSCLC) patients, treatment with BNP7787 in combination with standard chemotherapy resulted in substantial increases in the overall survival of patients with advanced adenocarcinoma of the lung in the first-line treatment setting. We hypothesized that BNP7787 might interact with and modify human anaplastic lymphoma kinase (ALK). At least seven different variants of ALK fusions with the gene encoding the echinoderm microtubule-associated protein-like 4 (EML4) are known to occur in NSCLC. EML4–ALK fusions are thought to account for approximately 3% of NSCLC cases. Herein, we report the covalent modification of the kinase domain of human ALK by a BNP7787-derived mesna moiety and the functional consequences of this modification in ALK assays evaluating kinase activity. The kinase domain of the ALK protein crystallizes as a monomer, and BNP7787-derived mesna-cysteine adducts were observed at Cys 1235 and Cys 1156. The BNP7787-derived mesna adduct at Cys 1156 is located in close proximity to the active site and results in substantial disorder of the P-loop and activation loop (A-loop). Comparison with the P-loop of apo-ALK suggests that the BNP7787-derived mesna adduct at Cys 1156 interferes with the positioning of Phe 1127 into a small pocket now occupied by mesna, resulting in a destabilization of the loop’s binding orientation. Additionally, in vitro kinase activity assays indicate that BNP7787 inhibits ALK catalytic activity and potentiates the activity of the ALK-targeted drug crizotinib.
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Analysis of Bordetella pertussis clinical isolates circulating in European countries during the period 1998-2012. Eur J Clin Microbiol Infect Dis 2014; 34:821-30. [PMID: 25527446 PMCID: PMC4365279 DOI: 10.1007/s10096-014-2297-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/07/2014] [Indexed: 12/31/2022]
Abstract
Despite more than 50 years of vaccination, pertussis is still an endemic disease, with regular epidemic outbreaks. With the exception of Poland, European countries have replaced whole-cell vaccines (WCVs) by acellular vaccines (ACVs) in the 1990s. Worldwide, antigenic divergence in vaccine antigens has been found between vaccine strains and circulating strains. In this work, 466 Bordetella pertussis isolates collected in the period 1998–2012 from 13 European countries were characterised by multi-locus antigen sequence typing (MAST) of the pertussis toxin promoter (ptxP) and of the genes coding for proteins used in the ACVs: pertussis toxin (Ptx), pertactin (Prn), type 2 fimbriae (Fim2) and type 3 fimbriae (Fim3). Isolates were further characterised by fimbrial serotyping, multi-locus variable-number tandem repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE). The results showed a very similar B. pertussis population for 12 countries using ACVs, while Poland, which uses a WCV, was quite distinct, suggesting that ACVs and WCVs select for different B. pertussis populations. This study forms a baseline for future studies on the effect of vaccination programmes on B. pertussis populations.
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Organic cleanliness of the Mars Science Laboratory sample transfer chain. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:075111. [PMID: 25085177 DOI: 10.1063/1.4890279] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
One of the primary science goals of the Mars Science Laboratory (MSL) Rover, Curiosity, is the detection of organics in Mars rock and regolith. To achieve this, the Curiosity rover includes a robotic sampling system that acquires rock and regolith samples and delivers it to the Sample Analysis at Mars (SAM) instrument on board the rover. In order to provide confidence that any significant organics detection result was Martian and not terrestrial in origin, a requirement was levied on the flight system (i.e., all sources minus the SAM instrument) to impart no more than 36 parts per billion (ppb by weight) of total reduced carbon terrestrial contamination to any sample transferred to the SAM instrument. This very clean level was achieved by a combination of a rigorous contamination control program on the project, and then using the first collected samples for a "dilution cleaning" campaign of the sample chain prior to delivering a sample to the SAM instrument. Direct cleanliness assays of the sample-contacting and other Flight System surfaces during pre-launch processing were used as inputs to determine the number of dilution cleaning samples needed once on Mars, to enable delivery of suitably clean samples to the SAM experiment. Taking into account contaminant redistribution during launch thorough landing of the MSL on Mars, the amount of residue present on the sampling hardware prior to the time of first dilution cleaning sample acquisition was estimated to be 60 ng/cm(2) on exposed outer surfaces of the sampling hardware and 20 ng/cm(2) on internal sample contacting surfaces; residues consisting mainly of aliphatic hydrocarbons and esters. After three dilution cleaning samples, estimated in-sample contamination level for the first regolith sample delivered to the SAM instrument at the Gale Crater "Rocknest" site was bounded at ≤10 ppb total organic carbon. A Project decision to forego ejecting the dilution cleaning sample and instead transfer the first drill-acquired sample at the "John Klein" site to SAM resulted in an estimated level of terrestrial contamination of ≤430 ppb. The estimated terrestrial contamination for portions from the second drill-acquired sample, at Cumberland, was ≤69 ppb; the estimate for a future, third, drilled sample is ≤38 ppb. These levels are comparable in magnitude to the SAM instrument blanks at the nanomole level (as chlorohydrocarbon).
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Identification and optimization of PDE10A inhibitors using fragment-based screening by nanocalorimetry and X-ray crystallography. ACTA ACUST UNITED AC 2013; 19:497-507. [PMID: 24375910 DOI: 10.1177/1087057113516493] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Fragment-based lead discovery (FBLD) is a technique in which small, low-complexity chemical fragments of 6 to 15 heavy atoms are screened for binding to or inhibiting activity of the target. Hits are then linked and/or elaborated into tightly binding ligands, ideally yielding early lead compounds for drug discovery. Calorimetry provides a label-free method to assay binding and enzymatic activity that is unaffected by the spectroscopic properties of the sample. Conventional microcalorimetry is hampered by requiring large quantities of reagents and long measurement times. Nanocalorimeters can overcome these limitations of conventional isothermal titration calorimetry. Here we use enthalpy arrays, which are arrays of nanocalorimeters, to perform an enzyme activity-based fragment screen for competitive inhibitors of phosphodiesterase 10A (PDE10A). Two dozen fragments with KI <2 mM were identified and moved to crystal soaking trials. All soak experiments yielded high-resolution diffraction, with two-thirds of the fragments yielding high-resolution co-crystal structures with PDE10A. The structural information was used to elaborate fragment hits, yielding leads with KI <1 µM. This study shows how array calorimetry can be used as a prescreening method for fragment-based lead discovery with enzyme targets and paired successfully with an X-ray crystallography secondary screen.
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Structure determination of LpxD from the lipopolysaccharide-synthesis pathway of Acinetobacter baumannii. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 69:6-9. [PMID: 23295477 DOI: 10.1107/s1744309112048890] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 11/28/2012] [Indexed: 11/10/2022]
Abstract
Acinetobacter baumannii is a Gram-negative bacterium that is resistant to many currently available antibiotics. The protein LpxD is a component of the biosynthetic pathway for lipopolysaccharides in the outer membrane of this bacterium and is a potential target for new antibacterial agents. This paper describes the structure determination of apo forms of LpxD in space groups P2(1) and P4(3)22. These crystals contained six and three copies of the protein molecule in the asymmetric unit and diffracted to 2.8 and 2.7 Å resolution, respectively. A comparison of the multiple protein copies in the asymmetric units of these crystals reveals a common protein conformation and a conformation in which the relative orientation between the two major domains in the protein is altered.
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Structure determination of LpxA from the lipopolysaccharide-synthesis pathway of Acinetobacter baumannii. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:1477-81. [PMID: 23192027 PMCID: PMC3509968 DOI: 10.1107/s174430911204571x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Accepted: 11/05/2012] [Indexed: 05/18/2024]
Abstract
Acinetobacter baumannii is a Gram-negative pathogenic bacterium which is resistant to most currently available antibiotics and that poses a significant health threat to hospital patients. LpxA is a key enzyme in the biosynthetic pathway of the lipopolysaccharides that are components of the bacterial outer membrane. It is a potential target for antibacterial agents that might be used to fight A. baumannii infections. This paper describes the structure determination of the apo form of LpxA in space groups P2(1)2(1)2(1) and P6(3). These crystal forms contained three and one protein molecules in the asymmetric unit and diffracted to 1.8 and 1.4 Å resolution, respectively. A comparison of the conformations of the independent protein monomers within and between the two crystal asymmetric units revealed very little structural variation across this set of structures. In the P6(3) crystal form the enzymatic site is exposed and is available for the introduction of small molecules of the type used in fragment-based drug discovery and structure-based lead optimization.
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The influence of larval density, food stress, and parasitism on the bionomics of the dengue vector Aedes aegypti (Diptera: Culicidae): implications for integrated vector management. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2012; 37:221-229. [PMID: 22548557 DOI: 10.1111/j.1948-7134.2012.00220.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
New larval control strategies for integrated vector management of Aedes aegypti are in high demand, including the use of biological control agents. Exposure of Aedes aegypti to parasites, starvation, and overcrowded conditions during larval development reduces the probability of survival to eclosion, can directly affect fitness parameters such as adult size and fecundity, and can affect the size, provisioning, and viability of eggs produced by females. We compared these parameters after exposing larvae to 1) abundant food at low larval densities, 2) food deprivation and high larval density, and 2) infection with the endoparasite Plagiorchis elegans, an entomopathogenic digenean trematode. Female mosquitoes that eclosed from larval conditions of starvation and overcrowding were smaller and laid fewer and smaller eggs than controls. The proportion of females to complete an oviposition cycle was reduced in the P. elegans-infected treatment group. Parasite load was negatively correlated with wing length and egg size. Infection of Ae. aegypti with P. elegans has sublethal effects and may reduce population-level reproductive output, but one-time low-density P. elegans exposure does not have sufficient effect on Ae. aegypti fitness parameters to be considered a viable biocontrol option.
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The structure of LpxD from Pseudomonas aeruginosa at 1.3 Å resolution. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:749-52. [PMID: 21795786 PMCID: PMC3144788 DOI: 10.1107/s1744309111018811] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 05/17/2011] [Indexed: 11/11/2022]
Abstract
LpxD is a bacterial protein that is part of the biosynthesis pathway of lipid A and is responsible for transferring 3-hydroxymyristic acid from the R-3-hydroxymyristoyl-acyl carrier protein to the 2-OH group of UDP-3-O-(3-hydroxymyristoyl) glucosamine. The crystal structure of LpxD from Pseudomonas aeruginosa has been determined at high resolution (1.3 Å). The crystal belonged to space group H3, with unit-cell parameters a=b=106.19, c=93.38 Å, and contained one molecule in the asymmetric unit. The structure was solved by molecular replacement using the known structure of LpxD from Escherichia coli (PDB entry 3eh0) as a search model and was refined to Rwork=16.4% (Rfree=18.5%) using 91,655 reflections. The final protein model includes 355 amino-acid residues (including 16 amino acids from a 20 amino-acid N-terminal His tag), one chloride ion and two ethylene glycol molecules.
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Wnt signaling and stem cell control. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2008; 73:59-66. [PMID: 19028988 DOI: 10.1101/sqb.2008.73.035] [Citation(s) in RCA: 186] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In many contexts, self-renewal and differentiation of stem cells are influenced by signals from their environment, constituting a niche. It is postulated that stem cells compete for local growth factors in the niche, thereby maintaining a balance between the numbers of self-renewing and differentiated cells. A critical aspect of the niche model for stem cell regulation is that the availability of self-renewing factors is limited and that stem cells compete for these factors (Fig. 1). Consequently, the range and concentrations of the niche factors are of critical importance. Now that some of the few self-renewing factors have become identified, aspects of the niche models can be tested experimentally. In this chapter, we address mechanisms of signal regulation that take place at the level of signal-producing cells, constituting a niche for stem cells. We emphasize the biochemical properties and posttranslational modifications of the signals, all in the context of Wnt signaling. We propose that these modifications control the range of Wnt signaling and have critical roles in establishing niches for stem cells in various tissues.
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Abstract
1501 Background: Tamoxifen and raloxifen reduce the risk of estrogen receptor (ER) positive breast cancer. Acceptance of SERMs is low due to toxicities. New agents with a better toxicity profile which also will prevent ER-negative breast cancer are needed. The cyclooxygenase II inhibitor celecoxib has antiproliferative, and antiangiogenetic properties and is a putative breast cancer prevention agent. Our objective in this prospective short-term prevention study was to evaluate the effect of celecoxib on biomarkers in breast tissue and serum of high risk women. Methods: High risk individuals with a history of atypical hyperplasia, or lobular carcinoma insitu, or Gail risk greater than 1.67%, or previous history of ER negative breast cancer were eligible. After signing informed consent subjects underwent baseline fine needle aspiration (FNA) of the breast and serum collection for biomarker analysis. Subjects started celecoxib at 400 mg po BID for 6 months and underwent repeat FNA and serum collection. Biomarker endpoints included changes in ER and KI-67 expression in breast tissue analyzed by immunohistochemistry and insulin like growth factor binding protein (IGFBP-1) in serum analyzed by ELISA. The difference in biomarkers before and after treatment was assessed using a Wilcoxon signed rank test. Results: 49 patients were enrolled and accrual has been completed. Median age was 51 years and 57% of women were postmenopausal. The mean pre- and post treatment ER expression was 35.5% and 31%, respectively. The difference in ER expression was not significant (p = 0.1). The mean pre- and post treatment KI-67 expression was 1.68% and 1.60%, respectively. The difference was not significant (p = 0.8). However, there was a statistically significant difference in pre- and post treatment IGFBP-1 levels (p=0.023), with pre-and post treatment levels being 6.81ng/ml and 11.51ng/ml, respectively. No grade 3 or 4 toxicities were observed and there was no drop-out from the study. Conclusions: We have found a significant modulation of IGFBP-1 levels with 6 months celecoxib treatment in women who are at increased risk of developing breast cancer. The acceptable side effect profile and modulation of the biomarker (IGFBP-1) provides support for continued evaluation of celecoxib as a breast cancer prevention agent. No significant financial relationships to disclose.
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[P200]: Role of ephrin B1 reverse signaling in development of the chick neural tube. Int J Dev Neurosci 2006. [DOI: 10.1016/j.ijdevneu.2006.09.260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Interleukin 17 induces cartilage collagen breakdown: novel synergistic effects in combination with proinflammatory cytokines. Ann Rheum Dis 2002; 61:704-13. [PMID: 12117676 PMCID: PMC1754191 DOI: 10.1136/ard.61.8.704] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To investigate whether interleukin 17 (IL17), derived specifically from T cells, can promote type II collagen release from cartilage. The ability of IL17 to synergise with other proinflammatory mediators to induce collagen release from cartilage, and what effect anti-inflammatory agents had on this process, was also assessed. METHODS IL17 alone, or in combination with IL1, IL6, oncostatin M (OSM), or tumour necrosis factor alpha (TNFalpha), was added to bovine nasal cartilage explant cultures. Proteoglycan and collagen release were determined. Collagenolytic activity was determined by bioassay. Chondroprotective effects of IL4, IL13, transforming growth factor beta1 (TGFbeta1) and insulin-like growth factor-1 (IGF1) were assessed by inclusion in the explant cultures. RESULTS IL17 alone stimulated a dose dependent release of proteoglycan and type II collagen from bovine nasal cartilage explants. Suboptimal doses of IL17 synergised potently with TNFalpha, IL1, OSM, and IL6 to promote collagen degradation. This collagen release was completely inhibited by tissue inhibitor of metalloproteinase-1 and BB-94 (a synthetic metalloproteinase inhibitor), and was significantly reduced by IL4, IL13, TGFbeta1, and IGF1. In IL17 treated chondrocytes, mRNA expression for matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13 was detected. Moreover, a synergistic induction of these MMPs was seen when IL17 was combined with other proinflammatory cytokines. CONCLUSIONS IL17 can, alone and synergistically in combination with other proinflammatory cytokines, promote chondrocyte mediated MMP dependent type II collagen release from cartilage. Because levels of all these proinflammatory cytokines are raised in rheumatoid synovial fluids, this study suggests that IL17 may act as a potent upstream mediator of cartilage collagen breakdown in inflammatory joint diseases.
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Cloning, overexpression, and characterization of peroxiredoxin and NADH peroxiredoxin reductase from Thermus aquaticus. J Biol Chem 2000; 275:30019-28. [PMID: 10862622 DOI: 10.1074/jbc.m004161200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The genes for peroxiredoxin (Prx) and NADH:peroxiredoxin oxidoreductase (PrxR) have been cloned from the thermophilic bacterium Thermus aquaticus. prx is located upstream from prxR, the two genes being separated by 13 bases. The amino acid sequences show that Prx is related to two-cysteine peroxiredoxins from a range of organisms and that PrxR resembles NADH-dependent flavoenzymes that catalyze the reduction of peroxiredoxins in mesophilic bacteria. The sequence of PrxR also resembles those of thioredoxin reductases (TrxR) from thermophiles but with an N-terminal extension of about 200 residues. PrxR has motifs for two redox-active disulfides, one in the FAD-binding site, as occurs in TrxR, and the other in the N-terminal extension. The molecular masses of the monomers of Prx and PrxR are 21.0 and 54.9 kDa, respectively; both enzymes exist as multimers. The recombinant flavoenzyme requires 3 mol equivalents of dithionite for full reduction, as is consistent with 1 FAD and 2 disulfides per monomer. PrxR and Prx together catalyze the anaerobic reduction of hydrogen peroxide. The activity of Prx is much less than has been observed with homologous proteins. Prx appears to be inactivated by cumene hydroperoxide. PrxR itself has low peroxidase activity.
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Eph receptors and ephrins in the developing chick cerebellum: relationship to sagittal patterning and granule cell migration. J Neurosci 2000; 20:6488-500. [PMID: 10964955 PMCID: PMC6772988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/1999] [Revised: 05/03/2000] [Accepted: 06/12/2000] [Indexed: 02/17/2023] Open
Abstract
Spatiotemporal expression patterns of six members of the Eph gene family (EphA4, EphA3, EphB2, ephrin-B1, ephrin-A2, and ephrin-A5) were characterized immunocytochemically at various stages of chick cerebellar development. EphA4 expression is observed in the cerebellar anlage as early as embryonic day 5 (E5) and continues in the posthatch cerebellum. During the early period of cerebellar development (E3-E8), complementarity is observed between EphA4 and ephrin-A5 expression within the cerebellar-isthmal region. By E8, differential expression of EphA4 in parasagittal Purkinje cell bands is evident, and the expression remains banded in the posthatch cerebellum. Banded expression of the ephrin-A5 ligand complements EphA4 expression during the middle period (E9-E15). During this period, ephrin-A2 and EphA3 are coexpressed in a banded pattern and with variable correlation to EphA4. Variability in the banding expression is observed for EphA4, EphA3, ephrin-A5, and ephrin-A2 across different lobes, and graded complementarity in the expression pattern of EphA3 and ephrin-A5 is observed in the external granular layer between the posterior and anterior lobes. Analysis of Purkinje cell birth date in correlation with Eph-ephrin expression during the middle period reveals that early-born cells express EphA4, whereas late-born cells express ephrin-A5. Finally, EphA4 expression domains are respected by migrating granule cell ribbons, which express both ephrin-B1 and EphB2. These expression patterns suggest multiple roles for the Eph-ephrin system in cerebellar development, including demarcation/enforcement of boundaries of the cerebellar anlage, formation/maintenance of Purkinje cell compartments, and restriction of the early phase of granule cell migration to ribbons.
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Engrailed-1 misexpression in chick embryos prevents apical ridge formation but preserves segregation of dorsal and ventral ectodermal compartments. Dev Biol 2000; 222:307-16. [PMID: 10837120 DOI: 10.1006/dbio.2000.9659] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using lineage tracers, we recently showed dorsal and ventral ectodermal compartments along the sides of the body in chick embryos. The compartments are formed both in presumptive limb-forming regions where they position the apical ridge and also in presumptive interlimb (flank). Here we show, using a novel technique combining fate mapping and in situ hybridisation, that the ventral compartment coincides with the Engrailed-1 (En-1) domain of expression. This coincidence suggests that En-1 could maintain the ventral compartment and be necessary for apical ridge formation. To test this hypothesis, we ectopically expressed En-1 via retroviral transfer and then examined limb development and cell lineage restriction in the ectoderm. En-1 misexpression can completely prevent formation of both normal limbs and ectopic limbs induced in the flank by application of FGF-2. In both cases, there are no morphological signs of apical ectodermal ridge formation and expression of ridge-associated genes is undetectable. In striking contrast, the lineage restriction between dorsal and ventral ectoderm is not altered. Therefore, En-1 is involved in the regulation of ridge formation but not compartment maintenance.
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Abstract
The Eph family is thought to exert its function through the complementary expression of receptors and ligands. Here, we show that EphA receptors colocalize on retinal ganglion cell (RGC) axons with EphA ligands, which are expressed in a high-nasal-to-low-temporal pattern. In the stripe assay, only temporal axons are normally sensitive for repellent axon guidance cues of the caudal tectum. However, overexpression of ephrinA ligands on temporal axons abolishes this sensitivity, whereas treatment with PI-PLC both removes ephrinA ligands from retinal axons and induces a striped outgrowth of formerly insensitive nasal axons. In vivo, retinal overexpression of ephrinA2 leads to topographic targeting errors of temporal axons. These data suggest that differential ligand expression on retinal axons is a major determinant of topographic targeting in the retinotectal projection.
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Abstract
We describe here how the early limb bud of the quail embryo develops in the absence of retinoids, including retinoic acid. Retinoid-deficient embryos develop to about stage 20/21, thus allowing patterns of early gene activity in the limb bud to be readily examined. Genes representing different aspects of limb polarity were analysed. Concerning the anteroposterior axis, Hoxb-8 was up-regulated and its border was shifted anteriorly whereas shh and the mesodermal expression of bmp-2 were down-regulated in the absence of retinoids. Concerning the apical ectodermal genes, fgf-4 was down-regulated whereas fgf-8 and the ectodermal domain of bmp-2 were unaffected. Genes involved in dorsoventral polarity were all disrupted. Wnt-7a, normally confined to the dorsal ectoderm, was ectopically expressed in the ventral ectoderm and the corresponding dorsal mesodermal gene Lmx-1 spread into the ventral mesoderm. En-1 was partially or completely absent from the ventral ectoderm. These dorsoventral patterns of expression resemble those seen in En-1 knockout mouse limb buds. Overall, the patterns of gene expression are also similar to the Japanese limbless mutant. These experiments demonstrate that the retinoid-deficient embryo is a valuable tool for dissecting pathways of gene activity in the limb bud and reveal for the first time a role for retinoic acid in the organisation of the dorsoventral axis.
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Effects of paired and unpaired eye-blink conditioning on Purkinje cell morphology. Learn Mem 1999; 6:128-37. [PMID: 10327238 PMCID: PMC311285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
This experiment addressed (1) the importance of conjunctive stimulus presentation for morphological plasticity of cerebellar Purkinje cells and inhibitory interneurons and (2) whether plasticity is restricted to the spiny branches of Purkinje cells, which receive parallel fiber input. These issues were investigated in naive rabbits and in rabbits that received paired or unpaired presentations of the conditioned stimulus (CS) and unconditioned stimulus (US). To direct CS input to the cerebellar cortex, pontine stimulation served as the CS. Air puffs to the cornea served as the US. Paired condition rabbits received pontine stimulation for 350 msec paired with a coterminating 100-msec air puff. Unpaired condition rabbits received the same stimuli in a pseudorandom order at 1- to 32-sec intervals. Rabbits were trained for a mean of 12 days. Naive rabbits received no treatment. In Golgi-stained Purkinje neurons in lobule HVI, total dendritic length, main branch length, total spiny branch length, and number of spiny branch arbors were all greater in the naive group than in the paired and unpaired groups, which did not differ. No differences were found between the hemispheres ipsilateral and contralateral to the trained eye. The dendritic length and number of branches for inhibitory interneurons did not differ across groups. The Purkinje cell morphological changes detected with these methods do not appear to be uniquely related to the conjunctive activation of the CS and US in the paired condition.
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Abstract
Experiments involving tissue recombinations have implicated both early vertical and later planar signals in the specification and polarisation of the midbrain. Here we investigate the role of fibroblast growth factors in regulating these processes in the avian embryo. We show that Fgf4 is expressed in the notochord anterior to Hensen's node before transcripts for the earliest molecular marker of midbrain tissue in the avian embryo, En1, are detected. The presence of notochord is required for the expression of En1 in neural plate explants in vitro and FGF4 mimics this effect of notochord tissue. Subsequently, a second member of the fibroblast growth factor family, Fgf8, is expressed in the isthmus in a manner consistent with it providing a polarising signal for the developing midbrain. Using a retroviral vector to express En1 ectopically, we show that En1 can induce Fgf8 expression in midbrain and posterior diencephalon. Results of the introduction of FGF8 protein into the anterior midbrain or posterior diencephalon are consistent with it being at least part of the isthmic activity which can repolarise the former tissue and respecify the latter to a midbrain fate. However, the ability of FGF8 to induce expression of genes which have earlier onsets of expression than Fgf8 itself, namely En1 and Pax2, strongly suggests that the normal function of FGF8 is in maintaining patterns of gene expression in posterior midbrain. Finally, we provide evidence that FGF8 also provides mitogenic stimulation during avian midbrain development.
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Tlx-1 and Tlx-3 homeobox gene expression in cranial sensory ganglia and hindbrain of the chick embryo: markers of patterned connectivity. J Neurosci 1998; 18:5389-402. [PMID: 9651221 PMCID: PMC6793508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/1998] [Revised: 04/28/1998] [Accepted: 05/06/1998] [Indexed: 02/08/2023] Open
Abstract
Recent evidence suggests that in vertebrates the formation of distinct neuronal cell types is controlled by specific families of homeodomain transcription factors. Furthermore, the expression domains of a number of these genes correlates with functionally integrated neuronal populations. We have isolated two members of the divergent T-cell leukemia translocation (HOX11/Tlx) homeobox gene family from chick, Tlx-1 and Tlx-3, and show that they are expressed in differentiating neurons of both the peripheral and central nervous systems. In the peripheral nervous system, Tlx-1 and Tlx-3 are expressed in overlapping domains within the placodally derived components of a number of cranial sensory ganglia. Tlx-3, unlike Tlx-1, is also expressed in neural crest-derived dorsal root and sympathetic ganglia. In the CNS, both genes are expressed in longitudinal columns of neurons at specific dorsoventral levels of the hindbrain. Each column has distinct anterior and/or posterior limits that respect inter-rhombomeric boundaries. Tlx-3 is also expressed in D2 and D3 neurons of the spinal cord. Tlx-1 and Tlx-3 expression patterns within the peripheral and central nervous systems suggest that Tlx proteins may be involved not only in the differentiation and/or survival of specific neuronal populations but also in the establishment of neuronal circuitry. Furthermore, by analogy with the LIM genes, Tlx family members potentially define sensory columns early within the developing hindbrain in a combinatorial manner.
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Malicious paraquat poisoning in Oklahoma dogs. VETERINARY AND HUMAN TOXICOLOGY 1998; 40:151-3. [PMID: 9610494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Paraquat is a restricted use herbicide which is extremely toxic to companion animals when ingested. This report details one incident of malicious poisoning involving 6 dogs. All dogs were from the same geographic area, and 5 had pulmonary and renal lesions consistent with paraquat toxicosis. Diagnosis was initiated by a modified dithionite spot test on vomitus from 1 dog. Subsequent tissue paraquat levels ranged from non-detectable to 1 ppm.
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Abstract
Expression and mutation analyses in mice suggest that the homeobox-containing gene Engrailed (En) plays a role in dorsoventral patterning of the limb. During the initial stages of limb bud outgrowth, En-1 mRNA and protein are uniformly distributed throughout the ventral limb bud ectoderm. Limbs of En-1(−/−) mice display a double dorsal phenotype suggesting that normal expression of En-1 in the ventral ectoderm is required to establish and/or maintain ventral limb characteristics. Loss of En-1 function also results in ventral expansion of the apical ectodermal ridge (AER), suggesting that En-1 is also required for proper formation of the AER. To further investigate the role En plays in dorsoventral patterning and AER formation, we have used the replication competent retroviral vector, RCAS, to mis-express mouse En-1 in the early chick limb bud. We show that ectopic En-1 expression in dorsal ectoderm is sufficient to repress the endogenous expression of the dorsal ectodermal marker Wnt7a, with a resultant decrease in Lmx1 expression in underlying dorsal mesenchyme. Furthermore, the AER is disrupted morphologically and the expression patterns of the AER signalling molecules Fgf-8 and Fgf-4 are altered. Consistent with recent evidence that there is a reciprocal interaction between signalling molecules in the dorsal ectoderm, AER, and zone of polarising activity (ZPA), loss of Wnt7a, Fgf-8 and Fgf-4 expression leads to a decrease in expression of the signalling molecule Shh in the ZPA. These results strongly support the idea that, in its normal domain of expression, En-1 represses Wnt7a-mediated dorsal differentiation by limiting the expression of Wnt7a to the dorsal ectoderm. Furthermore, our results provide additional evidence that En-1 is involved in AER formation and suggest that En-1 may act to define ventral ectodermal identity.
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Inaugural address. Ethics in the third millennium. THE JOURNAL OF THE ARKANSAS MEDICAL SOCIETY 1997; 94:9-18. [PMID: 9229582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Abstract
BACKGROUND Expression of the homeobox-containing gene Engrailed (En) in an increasing rostral-to-caudal gradient in the dorsal mesencephalon is the earliest known marker for polarity of the chick optic tectum. In heterotopic transplantation experiments, En protein expression correlates well with the subsequent gradient of cytoarchitecture as well as the pattern of retinotectal projections. The En gradient also correlates with the expression of two putative retinal axon-guidance molecules, RAGS and ELF-1, which are Eph-like receptor tyrosine kinase ligands that may function in the establishment of retinotopic projections by excluding temporal axons from the caudal tectum. RESULTS To examine the function of En in determining tectal polarity, we used the replication-competent retroviral vector RCAS to misexpress mouse En-1 throughout the chick tectal primordium. Our results show that the rostral portion of the tectum adopts a caudal phenotype: the gradient of cytoarchitectonic differentiation is abolished, and the molecular markers RAGS and ELF-1 are strongly expressed rostrally. In addition, cell membranes from rostral tectum of RCAS En-1-infected embryos preferentially repel temporal axons in in vitro membrane stripe assays. CONCLUSIONS These results are consistent with a role for En in determining rostrocaudal polarity of the developing tectum. The demonstration that both RAGS and ELF-1 are upregulated following En misexpression provides a molecular basis for understanding the previous observation, also based on retrovirus-mediated En misexpression, that nasal axons form ectopic connections in rostral tectum, from which temporal axons are excluded.
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A poor performance. Br Dent J 1994; 177:155. [PMID: 7917588 DOI: 10.1038/sj.bdj.4808531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Cloning and sequence comparison of the mouse, human, and chicken engrailed genes reveal potential functional domains and regulatory regions. ACTA ACUST UNITED AC 1993; 13:345-58. [PMID: 1363401 DOI: 10.1002/dvg.1020130505] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have isolated and characterized genomic DNA clones for the human and chicken homologues of the mouse En-1 and En-2 genes and determined the genomic structure and predicted protein sequences of both En genes in all three species. Comparison of these vertebrate En sequences with the Xenopus En-2 [Hemmati-Brivanlou et al., 1991) and invertebrate engrailed-like genes showed that the two previously identified highly conserved regions within the En protein ]reviewed in Joyner and Hanks, 1991] can be divided into five distinct subregions, designated EH1 to EH5. Sequences 5' and 3' to the predicted coding regions of the vertebrate En genes were also analyzed in an attempt to identify cis-acting DNA sequences important for the regulation of En gene expression. Considerable sequence similarity was found between the mouse and human homologues both within the putative 5' and 3' untranslated as well as 5' flanking regions. Between the mouse and Xenopus En-2 genes, shorter stretches of sequence similarity were found within the 3' untranslated region. The 5' untranslated regions of the mouse, chicken and Xenopus En-2 genes, however, showed no similarly conserved stretches. In a preliminary analysis of the expression pattern of the human En genes, En-2 protein and RNA were detected in the embryonic and adult cerebellum respectively and not in other tissues tested. These patterns are analogous to those seen in other vertebrates. Taken together these results further strengthen the suggestion that En gene function and regulation has been conserved throughout vertebrate evolution and, along with the five highly conserved regions within the En protein, raise an interesting question about the presence of conserved genetic pathways.
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Two enhancer regions in the mouse En-2 locus direct expression to the mid/hindbrain region and mandibular myoblasts. Development 1993; 117:905-16. [PMID: 8100765 DOI: 10.1242/dev.117.3.905] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
An En-2/lacZ gene fusion containing 9.5 kb of En-2 genomic DNA was capable of directing lacZ expression in an En-2-specific manner both temporally and spatially during embryogenesis and in the adult. lacZ expression was confined in the embryo to cells within the mid/hindbrain and mandibular arch regions and in the adult to cells of the molecular and granular layers of the cerebellum, and within the pons and colliculi regions. Interestingly, in the adult, transgene expression patterns within the cerebellum in two lines appeared to mark distinct anterior-posterior compartments. Analysis of the expression pattern of this transgene, in fetal and adult mice lacking a functional En-2 protein, provided evidence that the En-2 gene in mouse is not autoregulated. Deletion analysis of the En-2 genomic region and the use of a heterologous promoter identified two enhancer-containing regions of 1.5 and 1.0 kb in length, 5′ of the transcribed sequences, which independently directed expression in the embryo to either the mid/hindbrain region or mandibular myoblasts, respectively. The 1.5 kb fragment contains the most anterior neural enhancer and the 1.0 kb fragment, the earliest myogenic enhancer thus far characterized. These En-2-specific regulatory regions can now be used in a biochemical analysis to identify proteins important in anterior-posterior patterning of the vertebrate CNS and in the specification of muscle identity as well as in a mutational analysis to direct expression of other developmentally important genes to these regions.
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Abstract
The human homeobox-containing genes EN1 and EN2 are closely related to the Drosophila pattern formation gene engrailed (en), which may be important in brain development, as shown by gene expression studies during mouse embryogenesis. Here, we have refined the localization of EN1 to human chromosome 2q13-q21 using a mapping panel of rodent/human cell hybrids containing different regions of chromosome 2 and a lymphoblastoid cell line with an interstitial deletion, del(2)(q21-q23.2). This regional assignment of EN1 increases to 22 the number of currently known genes on human chromosome 2q that have homologs on the proximal region of mouse chromosome 1.
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Abstract
The object of this study was to determine if a strong association between soft drink (soda) consumption and recurrence of urinary stone disease, found in an earlier case-control study of adult males, had a causal component. The study sample consisted of 1009 male subjects, who completed an episode of urinary stone disease, who were aged 18-75 at that time, and who reported consuming at least 160 ml per day of soft drinks. Half of the subjects were randomized to refrain from consuming soft drinks, while the remaining subjects served as controls. The intervention group had an observed 6.4% advantage in actuarial 3 yr freedom from recurrence (p = 0.023 one-sided) over the control group. One important secondary finding was that for those who reported at the time of the index stone that their most consumed drink was acidified by phosphoric acid but not citric acid, the experimental group had a 15% higher 3 yr recurrence-free rate than the controls, p = 0.002, while for those who reported at the time of the index stone that their most consumed drink was acidified by citric acid with or without phosphoric acid, the experimental group had a similar 3 yr recurrence-free rate to the controls, p = 0.55. This interaction was significant, p = 0.019.
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Support for suspended surgeon. West J Med 1992. [DOI: 10.1136/bmj.304.6831.918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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