RESUMO
Acute myeloid leukaemia (AML) is a heterogeneous disease characterized by transcriptional dysregulation that results in a block in differentiation and increased malignant self-renewal. Various epigenetic therapies aimed at reversing these hallmarks of AML have progressed into clinical trials, but most show only modest efficacy owing to an inability to effectively eradicate leukaemia stem cells (LSCs)1. Here, to specifically identify novel dependencies in LSCs, we screened a bespoke library of small hairpin RNAs that target chromatin regulators in a unique ex vivo mouse model of LSCs. We identify the MYST acetyltransferase HBO1 (also known as KAT7 or MYST2) and several known members of the HBO1 protein complex as critical regulators of LSC maintenance. Using CRISPR domain screening and quantitative mass spectrometry, we identified the histone acetyltransferase domain of HBO1 as being essential in the acetylation of histone H3 at K14. H3 acetylated at K14 (H3K14ac) facilitates the processivity of RNA polymerase II to maintain the high expression of key genes (including Hoxa9 and Hoxa10) that help to sustain the functional properties of LSCs. To leverage this dependency therapeutically, we developed a highly potent small-molecule inhibitor of HBO1 and demonstrate its mode of activity as a competitive analogue of acetyl-CoA. Inhibition of HBO1 phenocopied our genetic data and showed efficacy in a broad range of human cell lines and primary AML cells from patients. These biological, structural and chemical insights into a therapeutic target in AML will enable the clinical translation of these findings.
Assuntos
Histona Acetiltransferases/metabolismo , Leucemia Mieloide Aguda/metabolismo , Células-Tronco Neoplásicas/metabolismo , Animais , Linhagem Celular Tumoral , Histona Acetiltransferases/química , Histona Acetiltransferases/genética , Humanos , Leucemia Mieloide Aguda/genética , Camundongos , Camundongos Endogâmicos C57BL , Modelos Moleculares , Estrutura Terciária de ProteínaRESUMO
TP 53-mutant acute myeloid leukemia (AML) remains the ultimate therapeutic challenge. Epichaperomes, formed in malignant cells, consist of heat shock protein 90 (HSP90) and associated proteins that support the maturation, activity, and stability of oncogenic kinases and transcription factors including mutant p53. High-throughput drug screening identified HSP90 inhibitors as top hits in isogenic TP53-wild-type (WT) and -mutant AML cells. We detected epichaperomes in AML cells and stem/progenitor cells with TP53 mutations but not in healthy bone marrow (BM) cells. Hence, we investigated the therapeutic potential of specifically targeting epichaperomes with PU-H71 in TP53-mutant AML based on its preferred binding to HSP90 within epichaperomes. PU-H71 effectively suppressed cell intrinsic stress responses and killed AML cells, primarily by inducing apoptosis; targeted TP53-mutant stem/progenitor cells; and prolonged survival of TP53-mutant AML xenograft and patient-derived xenograft models, but it had minimal effects on healthy human BM CD34+ cells or on murine hematopoiesis. PU-H71 decreased MCL-1 and multiple signal proteins, increased proapoptotic Bcl-2-like protein 11 levels, and synergized with BCL-2 inhibitor venetoclax in TP53-mutant AML. Notably, PU-H71 effectively killed TP53-WT and -mutant cells in isogenic TP53-WT/TP53-R248W Molm13 cell mixtures, whereas MDM2 or BCL-2 inhibition only reduced TP53-WT but favored the outgrowth of TP53-mutant cells. Venetoclax enhanced the killing of both TP53-WT and -mutant cells by PU-H71 in a xenograft model. Our data suggest that epichaperome function is essential for TP53-mutant AML growth and survival and that its inhibition targets mutant AML and stem/progenitor cells, enhances venetoclax activity, and prevents the outgrowth of venetoclax-resistant TP53-mutant AML clones. These concepts warrant clinical evaluation.
Assuntos
Antineoplásicos , Leucemia Mieloide Aguda , Humanos , Animais , Camundongos , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2 , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Apoptose , Células-Tronco/metabolismo , Linhagem Celular TumoralRESUMO
Singlet molecular oxygen (1O2) has well-established roles in photosynthetic plants, bacteria and fungi1-3, but not in mammals. Chemically generated 1O2 oxidizes the amino acid tryptophan to precursors of a key metabolite called N-formylkynurenine4, whereas enzymatic oxidation of tryptophan to N-formylkynurenine is catalysed by a family of dioxygenases, including indoleamine 2,3-dioxygenase 15. Under inflammatory conditions, this haem-containing enzyme is expressed in arterial endothelial cells, where it contributes to the regulation of blood pressure6. However, whether indoleamine 2,3-dioxygenase 1 forms 1O2 and whether this contributes to blood pressure control have remained unknown. Here we show that arterial indoleamine 2,3-dioxygenase 1 regulates blood pressure via formation of 1O2. We observed that in the presence of hydrogen peroxide, the enzyme generates 1O2 and that this is associated with the stereoselective oxidation of L-tryptophan to a tricyclic hydroperoxide via a previously unrecognized oxidative activation of the dioxygenase activity. The tryptophan-derived hydroperoxide acts in vivo as a signalling molecule, inducing arterial relaxation and decreasing blood pressure; this activity is dependent on Cys42 of protein kinase G1α. Our findings demonstrate a pathophysiological role for 1O2 in mammals through formation of an amino acid-derived hydroperoxide that regulates vascular tone and blood pressure under inflammatory conditions.
Assuntos
Pressão Sanguínea/fisiologia , Inflamação/sangue , Inflamação/fisiopatologia , Oxigênio Singlete/metabolismo , Vasodilatadores/metabolismo , Animais , Linhagem Celular , Proteína Quinase Dependente de GMP Cíclico Tipo I/antagonistas & inibidores , Proteína Quinase Dependente de GMP Cíclico Tipo I/química , Proteína Quinase Dependente de GMP Cíclico Tipo I/metabolismo , Cisteína/metabolismo , Ativação Enzimática/efeitos dos fármacos , Feminino , Humanos , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/farmacologia , Indolamina-Pirrol 2,3,-Dioxigenase/química , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Inflamação/enzimologia , Masculino , Oxirredução/efeitos dos fármacos , Ratos , Transdução de Sinais , Oxigênio Singlete/química , Triptofano/química , Triptofano/metabolismoRESUMO
Nature offers inspiration for developing technologies that integrate the capture, conversion, and storage of solar energy. In this review article, we highlight principles of natural photosynthesis and artificial photosynthesis, drawing comparisons between solar energy transduction in biology and emerging solar-to-fuel technologies. Key features of the biological approach include use of earth-abundant elements and molecular interfaces for driving photoinduced charge separation reactions that power chemical transformations at global scales. For the artificial systems described in this review, emphasis is placed on advancements involving hybrid photocathodes that power fuel-forming reactions using molecular catalysts interfaced with visible-light-absorbing semiconductors.
Assuntos
Fotossíntese , Energia Solar , Catálise , Luz , SemicondutoresRESUMO
Global challenges with treatment failures and/or widespread resistance in parasitic worms against commercially available anthelmintics lend impetus to the development of new anthelmintics with novel mechanism(s) of action. The free-living nematode Caenorhabditis elegans is an important model organism used for drug discovery, including the screening and structure-activity investigation of new compounds, and target deconvolution. Previously, we conducted a whole-organism phenotypic screen of the 'Pandemic Response Box' (from Medicines for Malaria Venture, MMV) and identified a hit compound, called ABX464, with activity against C. elegans and a related, parasitic nematode, Haemonchus contortus. Here, we tested a series of 44 synthesized analogues to explore the pharmacophore of activity on C. elegans and revealed five compounds whose potency was similar or greater than that of ABX464, but which were not toxic to human hepatoma (HepG2) cells. Subsequently, we employed thermal proteome profiling (TPP), protein structure prediction and an in silico-docking algorithm to predict ABX464-target candidates. Taken together, the findings from this study contribute significantly to the early-stage drug discovery of a new nematocide based on ABX464. Future work is aimed at validating the ABX464-protein interactions identified here, and at assessing ABX464 and associated analogues against a panel of parasitic nematodes, towards developing a new anthelmintic with a mechanism of action that is distinct from any of the compounds currently-available commercially.
Assuntos
Anti-Helmínticos , Nematoides , Quinolinas , Animais , Humanos , Caenorhabditis elegans , Anti-Helmínticos/farmacologia , Anti-Helmínticos/química , Relação Estrutura-AtividadeRESUMO
Acetylation of histones by lysine acetyltransferases (KATs) is essential for chromatin organization and function1. Among the genes coding for the MYST family of KATs (KAT5-KAT8) are the oncogenes KAT6A (also known as MOZ) and KAT6B (also known as MORF and QKF)2,3. KAT6A has essential roles in normal haematopoietic stem cells4-6 and is the target of recurrent chromosomal translocations, causing acute myeloid leukaemia7,8. Similarly, chromosomal translocations in KAT6B have been identified in diverse cancers8. KAT6A suppresses cellular senescence through the regulation of suppressors of the CDKN2A locus9,10, a function that requires its KAT activity10. Loss of one allele of KAT6A extends the median survival of mice with MYC-induced lymphoma from 105 to 413 days11. These findings suggest that inhibition of KAT6A and KAT6B may provide a therapeutic benefit in cancer. Here we present highly potent, selective inhibitors of KAT6A and KAT6B, denoted WM-8014 and WM-1119. Biochemical and structural studies demonstrate that these compounds are reversible competitors of acetyl coenzyme A and inhibit MYST-catalysed histone acetylation. WM-8014 and WM-1119 induce cell cycle exit and cellular senescence without causing DNA damage. Senescence is INK4A/ARF-dependent and is accompanied by changes in gene expression that are typical of loss of KAT6A function. WM-8014 potentiates oncogene-induced senescence in vitro and in a zebrafish model of hepatocellular carcinoma. WM-1119, which has increased bioavailability, arrests the progression of lymphoma in mice. We anticipate that this class of inhibitors will help to accelerate the development of therapeutics that target gene transcription regulated by histone acetylation.
Assuntos
Benzenossulfonatos/farmacologia , Senescência Celular/efeitos dos fármacos , Histona Acetiltransferases/antagonistas & inibidores , Hidrazinas/farmacologia , Linfoma/tratamento farmacológico , Linfoma/patologia , Sulfonamidas/farmacologia , Acetilação/efeitos dos fármacos , Animais , Benzenossulfonatos/uso terapêutico , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Desenvolvimento de Medicamentos , Fibroblastos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Histona Acetiltransferases/deficiência , Histona Acetiltransferases/genética , Histonas/química , Histonas/metabolismo , Hidrazinas/uso terapêutico , Linfoma/enzimologia , Linfoma/genética , Lisina/química , Lisina/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Moleculares , Sulfonamidas/uso terapêuticoRESUMO
The breeding of disease-resistant soybeans cultivars to manage Phytophthora root and stem rot caused by the pathogen Phytophthora sojae involves combining quantitative disease resistance (QDR) and Rps gene-mediated resistance. To identify and confirm potential mechanisms of QDR toward P. sojae, we conducted a time course study comparing changes in gene expression among Conrad and M92-220 with high QDR to susceptible genotypes, Sloan, and three mutants derived from fast neutron irradiation of M92-220. Differentially expressed genes from Conrad and M92-220 indicated several shared defense-related pathways at the transcriptomic level but also defense pathways unique to each cultivar, such as stilbenoid, diarylheptanoid, and gingerol biosynthesis and monobactam biosynthesis. Gene Ontology pathway analysis showed that the susceptible fast neutron mutants lacked enrichment of three terpenoid-related pathways and two cell wall-related pathways at either one or both time points, in contrast to M92-220. The susceptible mutants also lacked enrichment of potentially important Kyoto Encyclopedia of Genes and Genomes pathways at either one or both time points, including sesquiterpenoid and triterpenoid biosynthesis; thiamine metabolism; arachidonic acid; stilbenoid, diarylheptanoid, and gingerol biosynthesis; and monobactam biosynthesis. Additionally, 31 genes that were differentially expressed in M92-220 following P. sojae infection were not expressed in the mutants. These 31 genes have annotations related to unknown proteins; valine, leucine, and isoleucine biosynthesis; and protein and lipid metabolic processes. The results of this study confirm previously proposed mechanisms of QDR, provide evidence for potential novel QDR pathways in M92-220, and further our understanding of the complex network associated with QDR mechanisms in soybean toward P. sojae.
Assuntos
Resistência à Doença , Genótipo , Glycine max , Phytophthora , Doenças das Plantas , Transcriptoma , Glycine max/genética , Glycine max/microbiologia , Glycine max/imunologia , Phytophthora/fisiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/imunologia , Resistência à Doença/genética , Mutação , Regulação da Expressão Gênica de Plantas , Perfilação da Expressão GênicaRESUMO
The AP1 transcription factor ΔFOSB, a splice variant of FOSB, accumulates in the brain in response to chronic insults such as exposure to drugs of abuse, depression, Alzheimer's disease and tardive dyskinesias, and mediates subsequent long-term neuroadaptations. ΔFOSB forms heterodimers with other AP1 transcription factors, e.g. JUND, that bind DNA under control of a putative cysteine-based redox switch. Here, we reveal the structural basis of the redox switch by determining a key missing crystal structure in a trio, the ΔFOSB/JUND bZIP domains in the reduced, DNA-free form. Screening a cysteine-focused library containing 3200 thiol-reactive compounds, we identify specific compounds that target the redox switch, validate their activity biochemically and in cell-based assays, and show that they are well tolerated in different cell lines despite their general potential to bind to cysteines covalently. A crystal structure of the ΔFOSB/JUND bZIP domains in complex with a redox-switch-targeting compound reveals a deep compound-binding pocket near the DNA-binding site. We demonstrate that ΔFOSB, and potentially other, related AP1 transcription factors, can be targeted specifically and discriminately by exploiting unique structural features such as the redox switch and the binding partner to modulate biological function despite these proteins previously being thought to be undruggable.
Assuntos
Cisteína , Proteínas Proto-Oncogênicas c-fos , Proteínas Proto-Oncogênicas c-fos/metabolismo , Cisteína/genética , Cisteína/metabolismo , Regulação da Expressão Gênica , DNA/genética , DNA/metabolismo , Oxirredução , Fator de Transcrição AP-1/genética , Fator de Transcrição AP-1/metabolismoRESUMO
Endometrial cancer is the most frequent malignant tumor of the female reproductive tract but lacks effective therapy. EphA2, a receptor tyrosine kinase, is overexpressed by various cancers including endometrial cancer and is associated with poor clinical outcomes. In preclinical models, EphA2-targeted drugs had modest efficacy. To discover potential synergistic partners for EphA2-targeted drugs, we performed a high-throughput drug screen and identified panobinostat, a histone deacetylase inhibitor, as a candidate. We hypothesized that combination therapy with an EphA2 inhibitor and panobinostat leads to synergistic cell death. Indeed, we found that the combination enhanced DNA damage, increased apoptosis, and decreased clonogenic survival in Ishikawa and Hec1A endometrial cancer cells and significantly reduced tumor burden in mouse models of endometrial carcinoma. Upon RNA sequencing, the combination was associated with downregulation of cell survival pathways, including senescence, cyclins, and cell cycle regulators. The Axl-PI3K-Akt-mTOR pathway was also decreased by combination therapy. Together, our results highlight EphA2 and histone deacetylase as promising therapeutic targets for endometrial cancer.
Assuntos
Neoplasias do Endométrio , Inibidores de Histona Desacetilases , Receptor EphA2 , Animais , Feminino , Humanos , Camundongos , Apoptose , Linhagem Celular Tumoral , Neoplasias do Endométrio/tratamento farmacológico , Neoplasias do Endométrio/genética , Neoplasias do Endométrio/patologia , Inibidores de Histona Desacetilases/uso terapêutico , Panobinostat/farmacologia , Panobinostat/uso terapêutico , Fosfatidilinositol 3-Quinases , Terapia de Alvo Molecular , Receptor EphA2/antagonistas & inibidoresRESUMO
EphA2 tyrosine kinase is upregulated in many cancers and correlated with poor survival of patients, including those with endometrial cancer. EphA2-targeted drugs have shown modest clinical benefit. To improve the therapeutic response to such drugs, we performed a high-throughput chemical screen to discover novel synergistic partners for EphA2-targeted therapeutics. Our screen identified the Wee1 kinase inhibitor, MK1775, as a synergistic partner to EphA2, and this finding was confirmed using both in vitro and in vivo experiments. We hypothesized that Wee1 inhibition would sensitize cells to EphA2-targeted therapy. Combination treatment decreased cell viability, induced apoptosis, and reduced clonogenic potential in endometrial cancer cell lines. In vivo Hec1A and Ishikawa-Luc orthotopic mouse models of endometrial cancer showed greater anti-tumor responses to combination treatment than to either monotherapy. RNASeq analysis highlighted reduced cell proliferation and defective DNA damage response pathways as potential mediators of the combination's effects. In conclusion, our preclinical findings indicate that Wee1 inhibition can enhance the response to EphA2-targeted therapeutics in endometrial cancer; this strategy thus warrants further development.
Assuntos
Antineoplásicos , Neoplasias do Endométrio , Terapia de Alvo Molecular , Inibidores de Proteínas Quinases , Proteínas Tirosina Quinases , Receptor EphA2 , Animais , Feminino , Humanos , Camundongos , Antineoplásicos/uso terapêutico , Apoptose , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Neoplasias do Endométrio/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Tirosina Quinases/antagonistas & inibidores , Receptor EphA2/antagonistas & inibidoresRESUMO
Photoelectrosynthetic materials provide a bioinspired approach for using the power of the sun to produce fuels and other value-added chemical products. However, there remains an incomplete understanding of the operating principles governing their performance and thereby effective methods for their assembly. Herein we report the application of metalloporphyrins, several of which are known to catalyze the hydrogen evolution reaction, in forming surface coatings to assemble hybrid photoelectrosynthetic materials featuring an underlying gallium phosphide (GaP) semiconductor as a light capture and conversion component. The metalloporphyrin reagents used in this work contain a 4-vinylphenyl surface-attachment group at the ß-position of the porphyrin ring and a first-row transition metal ion (Fe, Co, Ni, Cu, or Zn) coordinated at the core of the macrocycle. In addition to describing the synthesis, optical, and electrochemical properties of the homogeneous porphyrin complexes, we also report on the photoelectrochemistry of the heterogeneous metalloporphyrin-modified GaP semiconductor electrodes. These hybrid, heterogeneous-homogeneous electrodes are prepared via UV-induced grafting of the homogeneous metalloporphyrin reagents onto the heterogeneous gallium phosphide surfaces. Three-electrode voltammetry measurements performed under controlled lighting conditions enable determination of the open-circuit photovoltages, fill factors, and overall current-voltage responses associated with these composite materials, setting the stage for better understanding charge-transfer and carrier-recombination kinetics at semiconductor|catalyst|liquid interfaces.
Assuntos
Gálio , Metaloporfirinas , Catálise , Metaloporfirinas/química , Fosfinas , SemicondutoresRESUMO
The intensive use of anesthetic and sedative agents in the neonatal intensive care unit (NICU) has raised controversial concerns about the potential neurodevelopmental risks. This study focused on midazolam (MDZ), a common benzodiazepine regularly used as a sedative on neonates in the NICU. Mounting evidence suggests a single exposure to MDZ during the neonatal period leads to learning disturbances. However, a knowledge gap that remains is how long-term exposure to MDZ during very early stages of life impacts synaptic alterations. Using a preclinical rodent model system, we mimicked a dose-escalation regimen on postnatal day 3 (P3) pups until day 21. Next, purified synaptosomes from P21 control and MDZ animals were subjected to quantitative mass-spectrometry-based proteomics, to identify potential proteomic signatures. Further analysis by ClueGO identified enrichment of proteins associated with actin-binding and protein depolymerization process. One potential hit identified was alpha adducin (ADD1), belonging to the family of cytoskeleton proteins, which was upregulated in the MDZ group and whose expression was further validated by Western blot. In summary, this study sheds new information on the long-term exposure of MDZ during the early stages of development impacts synaptic function, which could subsequently perturb neurobehavioral outcomes at later stages of life.
Assuntos
Midazolam , Proteoma , Animais , Hipnóticos e Sedativos/efeitos adversos , Midazolam/efeitos adversos , Proteômica , RatosRESUMO
Malaria is a devastating disease caused by Plasmodium parasites. Emerging resistance against current antimalarial therapeutics has engendered the need to develop antimalarials with novel structural classes. We recently described the identification and initial optimization of the 2-anilino quinazoline antimalarial class. Here, we refine the physicochemical properties of this antimalarial class with the aim to improve aqueous solubility and metabolism and to reduce adverse promiscuity. We show the physicochemical properties of this class are intricately balanced with asexual parasite activity and human cell cytotoxicity. Structural modifications we have implemented improved LipE, aqueous solubility and in vitro metabolism while preserving fast acting P. falciparum asexual stage activity. The lead compounds demonstrated equipotent activity against P. knowlesi parasites and were not predisposed to resistance mechanisms of clinically used antimalarials. The optimized compounds exhibited modest activity against early-stage gametocytes, but no activity against pre-erythrocytic liver parasites. Confoundingly, the refined physicochemical properties installed in the compounds did not engender improved oral efficacy in a P. berghei mouse model of malaria compared to earlier studies on the 2-anilino quinazoline class. This study provides the framework for further development of this antimalarial class.
Assuntos
Compostos de Anilina/química , Compostos de Anilina/farmacologia , Antimaláricos/química , Antimaláricos/farmacologia , Malária/tratamento farmacológico , Plasmodium/efeitos dos fármacos , Quinazolinas/química , Quinazolinas/farmacologia , Aminação , Compostos de Anilina/uso terapêutico , Animais , Antimaláricos/uso terapêutico , Feminino , Humanos , Malária/parasitologia , Camundongos , Plasmodium/fisiologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/fisiologia , Quinazolinas/uso terapêuticoRESUMO
Background Increased cerebral signal intensity (SI) has been reported in patients undergoing MRI with gadolinium-based contrast agents (GBCAs). Published data on gadobenate dimeglumine have been somewhat contradictory. Purpose To evaluate the relationship between dosage of gadobenate dimeglumine and SI change at MRI following multiple gadobenate dimeglumine administrations. Materials and Methods In this retrospective study, patients referred for clinically indicated brain MRI from January 2006 through May 2016 were evaluated for inclusion. Eligible patients were between 18 and 90 years old at their baseline brain MRI and had never received a GBCA, had undergone three or more MRI examinations with gadobenate dimeglumine, and had the baseline scan and another brain MRI scan available for comparison. The primary group consisted of patients with four or fewer supratentorial lesions smaller than 3 cm who underwent axial T1-weighted MRI at 1.5 T. One patient had also undergone prior radiation therapy. The secondary group consisted of patients with a history of brain radiation therapy or craniotomy who underwent 1.5-T and 3-T same-plane T1-weighted MRI (in any order). The SI for up to eight brain MRI examinations per patient was measured, and relative SI changes from baseline to interval scans were calculated. A subgroup analysis was performed to assess the gadobenate dimeglumine washout since the last gadolinium exposure. All patients had normal renal and liver functions. Linear mixed regression analyses were performed for variables with P < .05. Results In 43 patients (14 men, 29 women; median age, 49 years; age range, 25-73 years), the dentate nucleus (DN)-to-middle cerebral peduncle (MCP) SI ratio showed a mean increase of 6.7% ± 3.9 in the primary group and 4.0% ± 2.7 in the secondary group (both P < .001) following the administration of 134 mL ± 141 gadobenate dimeglumine over 55 months ± 35.2. The DN/MCP SI ratio increased linearly with the amount of gadobenate dimeglumine, with a mean increase of 0.015% ± 0.004 per 1 mL of gadobenate dimeglumine (R2 = 0.3, P < .001). Conclusion In patients receiving multiple doses of gadobenate dimeglumine, a linear relationship existed between gadobenate dimeglumine administrations and an increase in the dentate nucleus-to-middle cerebral peduncle signal intensity ratio at MRI. © RSNA, 2020 See also the editorial by McDonald and Kallmes in this issue.
Assuntos
Núcleos Cerebelares/diagnóstico por imagem , Meios de Contraste , Gadolínio DTPA , Aumento da Imagem/métodos , Imageamento por Ressonância Magnética/métodos , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
Sympathetically mediated contractions of smooth muscle cells in the vasa deferentia are mediated by neuronally released adenosine 5'-triphosphate (ATP) and noradrenaline, which stimulate P2X1-purinoceptors and α1A-adrenoceptors, respectively. This process is crucial for sperm transport, as demonstrated in knockout mouse studies where simultaneous genetic deletion of P2X1-purinoceptors and α1A-adrenoceptors resulted in male infertility. We hypothesize that dual pharmacological antagonism of these two receptors could inhibit sperm transport sufficiently to provide a novel nonhormonal method of male contraception. To generate a suitable P2X1-purinoceptor antagonist, substituents were introduced on the phenyl moiety of 2-phenyl-5,6,7,8-tetrahydroquinoxaline to create a series of analogues that were tested for P2X1-purinoceptor antagonism in isolated preparations of rat vas deferens. Novel compounds were initially screened for their ability to attenuate contractile responses to electrical field stimulation (EFS: 60 V, 0.5 ms, 0.2 Hz). The addition of polar substituents to the meta, but not ortho, position markedly increased the inhibition of contractions, as did the addition of both polar and aliphatic substituents to the para position. Di-substituted compounds were also synthesized and tested, resulting in a compound 31 (2-hydroxy, 4-fluoro), which exhibited the greatest potency, with an IC50 of 14 µM (95% confidence limits: 12-16 µM). Additionally, compound 31 noncompetitively antagonized contractions mediated by exogenously administered αß-methylene ATP (10 nM-30 µM) but had no inhibitory effect on contractions mediated by exogenously administered noradrenaline (30 nM-100 µM) or acetylcholine (30 nM-100 µM). These results have contributed to a structure-activity relationship profile for the P2X1-purinoceptor that will inform future designs of more potent antagonists.
Assuntos
Anticoncepcionais Masculinos , Indolizinas/química , Antagonistas do Receptor Purinérgico P2X/farmacologia , Ducto Deferente/efeitos dos fármacos , Animais , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Ratos , Receptores Purinérgicos P2X1/metabolismo , Pesquisa Translacional BiomédicaRESUMO
Kava extract, an aqueous rhizome emulsion of the plant Piper methysticum, has been used for centuries by Pacific Islanders as a ceremonial beverage, and has been sold as an anxiolytic agent for some decades. Kavalactones are a major constituent of kava extract. In a previous investigation, we had identified three kavalactones that inhibit larval development of Haemonchus contortus in an in vitro-bioassay. In the present study, we synthesized two kavalactones, desmethoxyyangonin and yangonin, as well as 17 analogues thereof, and evaluated their anthelmintic activities using the same bioassay as employed previously. Structure activity relationship (SAR) studies showed that a 4-substituent on the pendant aryl ring was required for activity. In particular, compounds with 4-trifluoromethoxy, 4-difluoromethoxy, 4-phenoxy, and 4-N-morpholine substitutions had anthelmintic activities (IC50 values in the range of 1.9 to 8.9 µM) that were greater than either of the parent natural products-desmethoxyyangonin (IC50 of 37.1 µM) and yangonin (IC50 of 15.0 µM). The synthesized analogues did not exhibit toxicity on HepG2 human hepatoma cells in vitro at concentrations of up to 40 µM. These findings confirm the previously-identified kavalactone scaffold as a promising chemotype for new anthelmintics and provide a basis for a detailed SAR investigation focused on developing a novel anthelmintic agent.
Assuntos
Anti-Helmínticos/síntese química , Anti-Helmínticos/farmacologia , Haemonchus/efeitos dos fármacos , Kava/química , Animais , Relação Dose-Resposta a Droga , Larva/efeitos dos fármacos , Estrutura Molecular , Testes de Sensibilidade ParasitáriaRESUMO
BACKGROUND: Functional Toll-like receptor 4 (TLR4) has been characterized in human and murine platelets indicating that platelets play a role in inflammation and hemostasis during sepsis. It is unclear whether canine platelets could express functional TLR4 by responding to its ligand, lipopolysaccharide (LPS). We sought to determine if dogs express functional TLR4 and if LPS-induced platelet activation requires co-stimulation with ADP or thromboxane A2 (TxA2). Canine platelets were unstimulated (resting) or activated with thrombin or ADP prior to flow cytometric or microscopic analyses for TLR4 expression. We treated resting or ADP-primed platelets with LPS in the absence or presence of acetylsalicylic acid (ASA) and inhibited TLR4 with function blocking antibody or LPS from Rhodobacter sphaeroides (LPS-RS). RESULTS: We discovered that dog platelets have variable TLR4 expression, which was upregulated following thrombin or ADP activation. LPS augmented P-selectin expression and thromboxane B2 secretion in ADP-primed platelets via TLR4. Inhibition of cyclooxygenase by ASA attenuated LPS-mediated P-selectin expression demonstrating that TLR4 signaling in platelets is partially dependent on TxA2 pathway. CONCLUSION: Expression of functional TLR4 on canine platelets may contribute to hypercoagulability in clinical septic dogs. Cyclooxygenase and TxA2 pathways in TLR4-mediated platelet activation may present novel therapeutic targets in dogs with sepsis.
Assuntos
Plaquetas/efeitos dos fármacos , Cães , Ativação Plaquetária/efeitos dos fármacos , Receptor 4 Toll-Like/metabolismo , Difosfato de Adenosina/farmacologia , Animais , Aspirina/farmacologia , Plaquetas/metabolismo , Lipopolissacarídeos/farmacologia , Rhodobacter sphaeroides/química , Tromboxano A2/farmacologiaRESUMO
OBJECTIVE: Measles is still common in many developing countries, and its outbreaks have been on the rise since 2009 even though the disease is almost entirely preventable through safe and effective vaccination. This paper aims to provide evidence about the systematic review of the cost-effectiveness of measles treatment in different regions worldwide. METHODS: The methodical search began on 10th January 2019 to look for all articles on the cost-effectiveness of measles treatment published from January 2019 to April 2019 in SCOPUS, Pubmed (www.ncbi.nlm.nih.gov) and Cochrane (www.cochrane.org).We summarised the articles by using a data table to extract all information using health economic evaluation methods. RESULTS: We identified 14 articles from the 69 total articles searched. These articles showed favourable costeffectiveness or cost-benefit ratios in high- and middle-income countries based on data organised by World Bank Income Level in 2018: the United States, Canada, Japan, India and Zambia. However, research is still limited in lowincome countries and thus the effectiveness of vaccination programmes cannot be conclusively identified. CONCLUSIONS: This review shows the overview of the research in health economic evaluations of measles in different places, years and using different methods of intervention. Overall, it evaluates the cost-effectiveness of measles treatment.
Assuntos
Vacina contra Sarampo/uso terapêutico , Sarampo/prevenção & controle , Análise Custo-Benefício , Humanos , Programas de Imunização/economia , Sarampo/economia , Vacina contra Sarampo/economia , Vacina contra Sarampo-Caxumba-Rubéola/economia , Vacina contra Sarampo-Caxumba-Rubéola/uso terapêuticoRESUMO
Field trials were conducted at two locations in Florida to evaluate transgenic tomato expressing the ELONGATION FACTOR TU RECEPTOR (EFR) gene from Arabidopsis thaliana, the Bs2 gene from pepper, or both Bs2 and EFR (Bs2/EFR) for managing bacterial wilt caused by Ralstonia solanacearum and bacterial spot caused by Xanthomonas perforans. Expression of EFR or Bs2/EFR in the susceptible genotype Fla. 8000 significantly reduced bacterial wilt incidence (50 to 100%) and increased total yield (57 to 114%) relative to lines expressing only Bs2 or the nontransformed Fla. 8000 control, although the marketable yield was not significantly affected. Following harvest, surviving symptomatic and nonsymptomatic plants were assessed for colonization by R. solanacearum. There were no significant differences in the population at the lower stem. Interestingly, in the middle stem, no bacteria could be recovered from EFR or Bs2/EFR lines but viable bacterial populations were recovered from Bs2 and nontransformed control lines at 102 to 105 CFU/g of stem tissue. In growth-chamber experiments, the EFR transgenic tomato lines were found to be effective against seven different R. solanacearum strains isolated from the southeastern United States, indicating utility across the southeastern United States. In all of the bacterial spot trials, EFR and Bs2/EFR lines had significantly reduced disease severity (22 to 98%) compared with the Fla. 8000 control. The marketable and total yield of Bs2/EFR were significantly higher (43 to 170%) than Fla. 8000 control in three of four field trials. These results demonstrate for the first time the potential of using the EFR gene for field management of bacterial wilt and bacterial spot diseases of tomato.
Assuntos
Proteínas de Arabidopsis/metabolismo , Doenças das Plantas/prevenção & controle , Proteínas de Plantas/metabolismo , Ralstonia solanacearum/fisiologia , Receptores de Reconhecimento de Padrão/metabolismo , Solanum lycopersicum/genética , Xanthomonas/fisiologia , Proteínas de Arabidopsis/genética , Florida , Expressão Gênica , Solanum lycopersicum/imunologia , Solanum lycopersicum/microbiologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Receptores de Reconhecimento de Padrão/genéticaRESUMO
PURPOSE: We report our initial clinical experience from a pilot study to compare the diagnostic accuracy of hybrid PET/MRI with PET/CT in colorectal cancer and discuss potential PET/MRI workflow solutions for colorectal cancer. METHODS: Patients underwent both FDG PET/CT and PET/MRI (Ingenuity TF PET/MRI, Philips Healthcare) for rectal cancer staging or colorectal cancer restaging. The PET acquisition of PET/MRI was similar to that of PET/CT whereas the MRI protocol was selected individually based on the patient's medical history. One nuclear medicine physician reviewed the PET/CT studies and one radiologist reviewed the PET/MRI studies independently. The diagnostic accuracy of each modality was determined in consensus, using available medical records as a reference. RESULTS: Of the 12 patients enrolled, two were for initial staging and ten for restaging. The median scan delay between the two modalities was 60 min. The initial imaging was PET/CT in nine patients and PET/MRI in three patients. When PET/CT was performed first, the SUV values of the 16 FDG avid lesions were greater at PET/MRI than at PET/CT. In contrast, when PET/MRI was performed first, the SUV values of the seven FDG avid lesions were greater at PET/CT than at PET/MRI. PET/MRI provided more detailed T staging than PET/CT. On a per-patient basis, with both patient groups combined for the evaluation of N and M staging/restaging, the true positive rate was 5/7 (71%) for PET/CT and 6/7 (86%) for PET/MRI, and true negative rate was 5/5 (100%) for both modalities. On a per-lesion basis, PET/CT identified 26 of 29 (90%) tumor lesions that were correctly detected by PET/MRI. Our proposed workflow allows for comprehensive cancer staging including integrated local and whole-body assessment. CONCLUSIONS: Our initial experience shows a high diagnostic accuracy of PET/MRI in T staging of rectal cancer compared with PET/CT. In addition, PET/MRI shows at least comparable accuracy in N and M staging as well as restaging to PET/CT. However, the small sample size limits the generalizability of the results. It is expected that PET/MRI would yield higher diagnostic accuracy than PET/CT considering the high soft tissue contrast provided by MRI compared with CT, but larger studies are necessary to fully assess the benefit of PET/MRI in colorectal cancer.