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1.
Mil Med ; 2024 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-38491995

RESUMO

INTRODUCTION: There is a longstanding debate about whether health care is more efficiently provided by the public or private sector. The debate is particularly relevant to the Military Health System (MHS), which delivers care through a combination of publicly funded federal facilities and privately contracted providers. This study compares outcomes, treatments, and costs for MHS patients obtaining care for low back pain (LBP) from public versus private providers. MATERIALS AND METHODS: A retrospective cohort study was completed using TRICARE Prime claims data from April 2015 to December 2018. The cohort was identified using International Classification of Diseases Ninth Revision and Tenth Revision diagnostic codes and then followed for 12 months after the index diagnosis to assess treatments, outcomes, and costs. Claims were classified as originating from either public or private providers. The primary outcome measure was resolution of LBP, defined as an absence of LBP diagnoses during the 6-to-12-month window following the index event. Instrumental variable models were used to assess the impact of care setting (i.e., private versus public), conditioning on the covariates. A regional measure of the fraction of private care was used as an instrument. RESULTS: Resolution of LBP was achieved for 79.7% of 144,866 patients in the cohort. No significant association was found between resolution of LBP and fraction of privately provided care. Higher fraction of private care was associated with a greater likelihood of opioid treatments (odds ratio, 1.22; 95% CI, 1.02-1.46) and a lower likelihood of benzodiazepine (odds ratio, 0.56; 95% CI, 0.45-0.70) and physical therapy (odds ratio 0.55; 95% CI, 0.42-0.74) treatments; manual therapy was not significantly associated with the fraction of private care. There was a significant negative association between the fraction of private care and cost (coefficient -0.27; 95% CI, -0.44, -0.10). CONCLUSION: This study found that privately provided care was associated with significantly higher opioid prescribing, less use of benzodiazepines and physical therapy, and lower costs. No systematic differences in outcomes (as measured by resolved cases) were identified. The findings suggest that publicly funded health care within the MHS context can attain quality comparable to privately provided care, although differences in treatment choices and costs point to possibilities for improved care within both systems.

2.
Artigo em Inglês | MEDLINE | ID: mdl-38490619

RESUMO

PURPOSE: Disparities in access to a multidisciplinary cancer consultation (MDCc) persist, and the role of physician relationships remains understudied. This study examined the extent to which multilevel factors, including patient characteristics and patient-sharing network measures reflecting the structure of physician relationships, are associated with an MDCc and receipt of stereotactic body radiation therapy versus surgery among patients with early-stage non-small cell lung cancer (NSCLC). METHODS AND MATERIALS: In this cross-sectional study, we analyzed Surveillance, Epidemiology, and End Results (SEER)-Medicare data for patients diagnosed with stage I-IIA NSCLC from 2016 to 2017. We assembled patient-sharing networks and identified cancer specialists who were locally unique for their specialty, herein referred to as linchpins. The proportion of linchpin cancer specialists for each hospital referral region (HRR) was calculated as a network-based measure of specialist scarcity. We used multilevel multinomial logistic regression to estimate associations between study variables and receipt of an MDCc and multilevel logistic regression to examine the relationship between patient receipt of an MDCc and initial treatment. RESULTS: Our study included 6120 patients with stage I-IIA NSCLC, of whom 751 (12.3%) received an MDCc, 1729 (28.3%) consulted only a radiation oncologist, 2010 (32.8%) consulted only a surgeon, and 1630 (26.6%) consulted neither specialist within 2 months of diagnosis. Compared with patients residing in an HRR with a low proportion of linchpin surgeons, those residing in an HRR with a high proportion of linchpin surgeons had a 2.99 (95% CI, 1.87-4.78) greater relative risk of consulting only a radiation oncologist versus receiving an MDCc and a 2.70 (95% CI, 1.68-4.35) greater relative risk of consulting neither specialist versus receiving an MDCc. Patients who received an MDCc were 5.32 times (95% CI, 4.27-6.63) more likely to receive stereotactic body radiation therapy versus surgery. CONCLUSIONS: Physician networks are associated with receipt of an MDCc and treatment, underscoring the potential for leveraging patient-sharing network analysis to improve access to lung cancer care.

3.
J Natl Cancer Inst ; 116(2): 230-238, 2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-37676831

RESUMO

BACKGROUND: Patients with cancer frequently require multidisciplinary teams for optimal cancer outcomes. Network analysis can capture relationships among cancer specialists, and we developed a novel physician linchpin score to characterize "linchpin" physicians whose peers have fewer ties to other physicians of the same oncologic specialty. Our study examined whether being treated by a linchpin physician was associated with worse survival. METHODS: In this cross-sectional study, we analyzed Surveillance, Epidemiology, and End Results-Medicare data for patients diagnosed with stage I to III non-small cell lung cancer or colorectal cancer (CRC) in 2016-2017. We assembled patient-sharing networks and calculated linchpin scores for medical oncologists, radiation oncologists, and surgeons. Physicians were considered linchpins if their linchpin score was within the top 15% for their specialty. We used Cox proportional hazards models to examine associations between being treated by a linchpin physician and survival, with a 2-year follow-up period. RESULTS: The study cohort included 10 081 patients with non-small cell lung cancer and 9036 patients with CRC. Patients with lung cancer treated by a linchpin radiation oncologist had a 17% (95% confidence interval = 1.04 to 1.32) greater hazard of mortality, and similar trends were observed for linchpin medical oncologists. Patients with CRC treated by a linchpin surgeon had a 22% (95% confidence interval = 1.03 to 1.43) greater hazard of mortality. CONCLUSIONS: In an analysis of Medicare beneficiaries with nonmetastatic lung cancer or CRC, those treated by linchpin physicians often experienced worse survival. Efforts to improve outcomes can use network analysis to identify areas with reduced access to multidisciplinary specialists.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Médicos , Humanos , Idoso , Estados Unidos/epidemiologia , Carcinoma Pulmonar de Células não Pequenas/terapia , Estudos Transversais , Neoplasias Pulmonares/terapia , Programa de SEER , Medicare
4.
bioRxiv ; 2023 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-37961641

RESUMO

Human papillomavirus (HPV) integration has been implicated in transforming HPV infection into cancer, but its genomic consequences have been difficult to study using short-read technologies. To resolve the dysregulation associated with HPV integration, we performed long-read sequencing on 63 cervical cancer genomes. We identified six categories of integration events based on HPV-human genomic structures. Of all HPV integrants, defined as two HPV-human breakpoints bridged by an HPV sequence, 24% contained variable copies of HPV between the breakpoints, a phenomenon we termed heterologous integration. Analysis of DNA methylation within and in proximity to the HPV genome at individual integration events revealed relationships between methylation status of the integrant and its orientation and structure. Dysregulation of the human epigenome and neighboring gene expression in cis with the HPV-integrated allele was observed over megabase-ranges of the genome. By elucidating the structural, epigenetic, and allele-specific impacts of HPV integration, we provide insight into the role of integrated HPV in cervical cancer.

5.
J Pharmacol Exp Ther ; 369(2): 182-187, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30765424

RESUMO

Platelets are key mediators of thrombosis. Many agonists of platelet activation are known, but fewer endogenous inhibitors of platelets, such as prostacyclin and nitric oxide (NO), have been identified. Acetylcholinesterase inhibitors, such as donepezil, can cause bleeding in patients, but the underlying mechanisms are not well understood. We hypothesized that acetylcholine is an endogenous inhibitor of platelets. We measured the effect of acetylcholine or analogs of acetylcholine on human platelet activation ex vivo. Acetylcholine and analogs of acetylcholine inhibited platelet activation, as measured by P-selectin translocation and glycoprotein IIb IIIa conformational changes. Conversely, we found that antagonists of the acetylcholine receptor, such as pancuronium, enhance platelet activation. Furthermore, drugs inhibiting acetylcholinesterase, such as donepezil, also inhibit platelet activation, suggesting that platelets release acetylcholine. We found that NO mediates acetylcholine inhibition of platelets. Our data suggest that acetylcholine is an endogenous inhibitor of platelet activation. The cholinergic system may be a novel target for antithrombotic therapies.


Assuntos
Acetilcolina/farmacologia , Ativação Plaquetária/efeitos dos fármacos , Acetilcolina/metabolismo , Plaquetas/efeitos dos fármacos , Plaquetas/fisiologia , Humanos , Óxido Nítrico/metabolismo , Receptores Colinérgicos/metabolismo
6.
Arterioscler Thromb Vasc Biol ; 38(7): 1594-1606, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29724818

RESUMO

OBJECTIVE: Reduced blood flow and tissue oxygen tension conditions result from thrombotic and vascular diseases such as myocardial infarction, stroke, and peripheral vascular disease. It is largely assumed that while platelet activation is increased by an acute vascular event, chronic vascular inflammation, and ischemia, the platelet activation pathways and responses are not themselves changed by the disease process. We, therefore, sought to determine whether the platelet phenotype is altered by hypoxic and ischemic conditions. APPROACH AND RESULTS: In a cohort of patients with metabolic and peripheral artery disease, platelet activity was enhanced, and inhibition with oral antiplatelet agents was impaired compared with platelets from control subjects, suggesting a difference in platelet phenotype caused by the disease. Isolated murine and human platelets exposed to reduced oxygen (hypoxia chamber, 5% O2) had increased expression of some proteins that augment platelet activation compared with platelets in normoxic conditions (21% O2). Using a murine model of critical limb ischemia, platelet activity was increased even 2 weeks postsurgery compared with sham surgery mice. This effect was partly inhibited in platelet-specific ERK5 (extracellular regulated protein kinase 5) knockout mice. CONCLUSIONS: These findings suggest that ischemic disease changes the platelet phenotype and alters platelet agonist responses because of changes in the expression of signal transduction pathway proteins. Platelet phenotype and function should, therefore, be better characterized in ischemic and hypoxic diseases to understand the benefits and limitations of antiplatelet therapy.


Assuntos
Plaquetas/metabolismo , Hipóxia/sangue , Isquemia/sangue , Oxigênio/sangue , Doença Arterial Periférica/sangue , Ativação Plaquetária , Animais , Plaquetas/efeitos dos fármacos , Estudos de Casos e Controles , Estado Terminal , Modelos Animais de Doenças , Humanos , Hipóxia/fisiopatologia , Isquemia/tratamento farmacológico , Isquemia/fisiopatologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Quinase 7 Ativada por Mitógeno/sangue , Proteína Quinase 7 Ativada por Mitógeno/genética , Doença Arterial Periférica/tratamento farmacológico , Doença Arterial Periférica/fisiopatologia , Fenótipo , Ativação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/uso terapêutico , Pneumonectomia , Transdução de Sinais
7.
Transl Res ; 195: 1-12, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29274308

RESUMO

It is assumed that platelets in diseased conditions share similar properties to platelets in healthy conditions, although this has never been examined in detail for myocardial infarction (MI). We examined platelets from patients with ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI) compared with platelets from healthy volunteers to evaluate for differences in platelet phenotype and function. Platelet activation was examined and postreceptor signal transduction pathways were assessed. Platelet-derived plasma biomarkers were evaluated by receiver operator characteristic curve analysis. Maximum platelet activation through the thromboxane receptor was greater in STEMI than in NSTEMI but less through protease-activated receptor 1. Extracellular-signal related-kinase 5 activation, which can activate platelets, was increased in platelets from subjects with STEMI and especially in platelets from patients with NSTEMI. Matrix metalloproteinase 9 (MMP9) protein content and enzymatic activity were several-fold greater in platelets with MI than in control. Mean plasma MMP9 concentration in patients with MI distinguished between STEMI and NSTEMI (area under curve [AUC] 75% [confidence interval (CI) 60-91], P = 0.006) which was superior to troponin T (AUC 66% [CI 48-85, P = 0.08), predicting STEMI with 80% sensitivity (95% CI 56-94), 90% specificity (CI 68-99), 70% AUC (CI 54-86, P < 0.0001), and NSTEMI with 50% sensitivity (CI 27-70), 90% specificity (CI 68-99), 70% AUC (CI 54-86, P = 0.03). Platelets from patients with STEMI and NSTEMI show differences in platelet surface receptor activation and postreceptor signal transduction, suggesting the healthy platelet phenotype in which antiplatelet agents are often evaluated in preclinical studies is different from platelets in patients with MI.


Assuntos
Plaquetas/fisiologia , Infarto do Miocárdio/sangue , Infarto do Miocárdio com Supradesnível do Segmento ST/sangue , Idoso , Feminino , Humanos , Masculino , Metaloproteinase 9 da Matriz/sangue , Pessoa de Meia-Idade , Fenótipo , Receptor PAR-1/fisiologia , Receptores Purinérgicos P2Y12/fisiologia
8.
Haematologica ; 102(2): 295-307, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27634200

RESUMO

Acquired aplastic anemia is an autoimmune-mediated bone marrow failure syndrome. The mechanism by which such an autoimmune reaction is initiated is unknown. Whether and how the genetic lesions detected in patients cause autoimmune bone marrow failure have not yet been determined. We found that mice with spontaneous deletion of the TGFß-activated kinase-1 gene in a small subset of hematopoietic cells developed bone marrow failure which resembled the clinical manifestations of acquired aplastic anemia patients. Bone marrow failure in such mice could be reversed by depletion of CD4+ T lymphocytes or blocked by knockout of interferon-γ, suggesting a Th1-cell-mediated autoimmune mechanism. The onset and progression of bone marrow failure in such mice were significantly accelerated by the inactivation of tumor necrosis factor-α signaling. Tumor necrosis factor-α restricts autoimmune bone marrow failure by inhibiting type-1 T-cell responses and maintaining the function of myeloid-derived suppressor cells. Furthermore, we determined that necroptosis among a small subset of mutant hematopoietic cells is the cause of autoimmune bone marrow failure because such bone marrow failure can be prevented by deletion of receptor interacting protein kinase-3 Our study suggests a novel mechanism to explain the pathogenesis of autoimmune bone marrow failure.


Assuntos
Apoptose , Autoimunidade , Células da Medula Óssea/imunologia , Células da Medula Óssea/metabolismo , Medula Óssea/imunologia , Medula Óssea/metabolismo , Mutação , Necrose , Anemia Aplástica/etiologia , Anemia Aplástica/metabolismo , Anemia Aplástica/mortalidade , Anemia Aplástica/patologia , Animais , Apoptose/genética , Apoptose/imunologia , Biomarcadores , Medula Óssea/patologia , Modelos Animais de Doenças , Progressão da Doença , Feminino , Hematopoese/genética , Hematopoese/imunologia , Células-Tronco Hematopoéticas/imunologia , Células-Tronco Hematopoéticas/metabolismo , Interferon gama/deficiência , Ativação Linfocitária , MAP Quinase Quinase Quinases/genética , Masculino , Camundongos , Camundongos Knockout , Necrose/genética , Necrose/imunologia , Proteína Serina-Treonina Quinases de Interação com Receptores/deficiência , Transdução de Sinais , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Fator de Necrose Tumoral alfa/metabolismo
9.
FEMS Microbiol Lett ; 363(9)2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-27030728

RESUMO

Several Gram-positive pathogens scavenge host-derived heme to satisfy their nutritional iron requirement. However, heme is a toxic molecule capable of damaging the bacterial cell. Gram-positive pathogens within the phylum Firmicutes overcome heme toxicity by sensing heme through HssRS, a two-component system that regulates the heme detoxification transporter HrtAB. Here we show that heme sensing by HssRS and heme detoxification by HrtAB occur in the insect pathogen Bacillus thuringiensis We find that in B. thuringiensis, HssRS directly regulates an operon, hrmXY, encoding hypothetical membrane proteins that are not found in other Firmicutes with characterized HssRS and HrtAB systems. This novel HssRS-regulated operon or its orthologs BMB171_c3178 and BMB171_c3330 are required for maximal heme resistance. Furthermore, the activity of HrmXY is not dependent on expression of HrtAB. These results suggest that B. thuringiensis senses heme through HssRS and induces expression of separate membrane-localized systems capable of overcoming different aspects of heme toxicity.


Assuntos
Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Regulação Bacteriana da Expressão Gênica , Heme/metabolismo , Bacillus thuringiensis/patogenicidade , Bacillus thuringiensis/fisiologia , Proteínas de Bactérias/genética , Transporte Biológico , Ferro/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Mutação , Óperon , Regiões Promotoras Genéticas
10.
Int J Radiat Oncol Biol Phys ; 92(2): 228-35, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25847605

RESUMO

PURPOSE: The purpose of this study was to quantify the frequency and clinical severity of quality deficiencies in intensity modulated radiation therapy (IMRT) planning in the Radiation Therapy Oncology Group 0126 protocol. METHODS AND MATERIALS: A total of 219 IMRT patients from the high-dose arm (79.2 Gy) of RTOG 0126 were analyzed. To quantify plan quality, we used established knowledge-based methods for patient-specific dose-volume histogram (DVH) prediction of organs at risk and a Lyman-Kutcher-Burman (LKB) model for grade ≥2 rectal complications to convert DVHs into normal tissue complication probabilities (NTCPs). The LKB model was validated by fitting dose-response parameters relative to observed toxicities. The 90th percentile (22 of 219) of plans with the lowest excess risk (difference between clinical and model-predicted NTCP) were used to create a model for the presumed best practices in the protocol (pDVH0126,top10%). Applying the resultant model to the entire sample enabled comparisons between DVHs that patients could have received to DVHs they actually received. Excess risk quantified the clinical impact of suboptimal planning. Accuracy of pDVH predictions was validated by replanning 30 of 219 patients (13.7%), including equal numbers of presumed "high-quality," "low-quality," and randomly sampled plans. NTCP-predicted toxicities were compared to adverse events on protocol. RESULTS: Existing models showed that bladder-sparing variations were less prevalent than rectum quality variations and that increased rectal sparing was not correlated with target metrics (dose received by 98% and 2% of the PTV, respectively). Observed toxicities were consistent with current LKB parameters. Converting DVH and pDVH0126,top10% to rectal NTCPs, we observed 94 of 219 patients (42.9%) with ≥5% excess risk, 20 of 219 patients (9.1%) with ≥10% excess risk, and 2 of 219 patients (0.9%) with ≥15% excess risk. Replanning demonstrated the predicted NTCP reductions while maintaining the volume of the PTV receiving prescription dose. An equivalent sample of high-quality plans showed fewer toxicities than low-quality plans, 6 of 73 versus 10 of 73 respectively, although these differences were not significant (P=.21) due to insufficient statistical power in this retrospective study. CONCLUSIONS: Plan quality deficiencies in RTOG 0126 exposed patients to substantial excess risk for rectal complications.


Assuntos
Benchmarking/normas , Órgãos em Risco/efeitos da radiação , Neoplasias da Próstata/radioterapia , Lesões por Radiação/diagnóstico , Planejamento da Radioterapia Assistida por Computador/efeitos adversos , Radioterapia de Intensidade Modulada/efeitos adversos , Reto/efeitos da radiação , Benchmarking/métodos , Relação Dose-Resposta à Radiação , Humanos , Masculino , Modelos Estatísticos , Tratamentos com Preservação do Órgão/normas , Qualidade da Assistência à Saúde , Lesões por Radiação/etiologia , Planejamento da Radioterapia Assistida por Computador/normas , Radioterapia de Intensidade Modulada/métodos , Radioterapia de Intensidade Modulada/normas , Medição de Risco
11.
Cell Rep ; 10(12): 2055-68, 2015 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-25801032

RESUMO

Mutations and inactivation of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) are observed in 15%-25% of cases of human T cell acute lymphoblastic leukemia (T-ALL). Pten deletion induces myeloproliferative disorders (MPDs), acute myeloid leukemia (AML), and/or T-ALL in mice. Previous studies attributed Pten-loss-related hematopoietic defects and leukemogenesis to excessive activation of phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling. Although inhibition of this signal dramatically suppresses the growth of PTEN-null T-ALL cells in vitro, treatment with inhibitors of this pathway does not cause a complete remission in vivo. Here, we report that focal adhesion kinase (Fak), a protein substrate of Pten, also contributes to T-ALL development in Pten-null mice. Inactivation of the FAK signaling pathway by either genetic or pharmacologic methods significantly sensitizes both murine and human PTEN-null T-ALL cells to PI3K/AKT/mTOR inhibition when cultured in vitro on feeder layer cells or a matrix and in vivo.


Assuntos
Proteína-Tirosina Quinases de Adesão Focal/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Animais , Humanos , Leucemia/metabolismo , Camundongos , Camundongos Knockout , Transdução de Sinais/efeitos dos fármacos
12.
J Exp Med ; 211(6): 1093-108, 2014 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-24842373

RESUMO

Leukemic stem cells (LSCs) isolated from acute myeloid leukemia (AML) patients are more sensitive to nuclear factor κB (NF-κB) inhibition-induced cell death when compared with hematopoietic stem and progenitor cells (HSPCs) in in vitro culture. However, inadequate anti-leukemic activity of NF-κB inhibition in vivo suggests the presence of additional survival/proliferative signals that can compensate for NF-κB inhibition. AML subtypes M3, M4, and M5 cells produce endogenous tumor necrosis factor α (TNF). Although stimulating HSPC with TNF promotes necroptosis and apoptosis, similar treatment with AML cells (leukemic cells, LCs) results in an increase in survival and proliferation. We determined that TNF stimulation drives the JNK-AP1 pathway in a manner parallel to NF-κB, leading to the up-regulation of anti-apoptotic genes in LC. We found that we can significantly sensitize LC to NF-κB inhibitor treatment by blocking the TNF-JNK-AP1 signaling pathway. Our data suggest that co-inhibition of both TNF-JNK-AP1 and NF-κB signals may provide a more comprehensive treatment paradigm for AML patients with TNF-expressing LC.


Assuntos
Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Leucemia Mieloide Aguda/metabolismo , NF-kappa B/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Antracenos/farmacologia , Western Blotting , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Células Cultivadas , Regulação Leucêmica da Expressão Gênica/efeitos dos fármacos , Células HL-60 , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases JNK Ativadas por Mitógeno/genética , Células K562 , Leucemia Monocítica Aguda/genética , Leucemia Monocítica Aguda/metabolismo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Leucemia Mielomonocítica Aguda/genética , Leucemia Mielomonocítica Aguda/metabolismo , Leucemia Promielocítica Aguda/genética , Leucemia Promielocítica Aguda/metabolismo , Camundongos , Camundongos Knockout , NF-kappa B/antagonistas & inibidores , NF-kappa B/genética , Nitrilas/farmacologia , Receptores do Fator de Necrose Tumoral/genética , Receptores do Fator de Necrose Tumoral/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Sulfonas/farmacologia , Fator de Transcrição AP-1/genética , Fator de Transcrição AP-1/metabolismo , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/farmacologia , Células U937
13.
J Med Chem ; 57(5): 1902-13, 2014 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-23672667

RESUMO

A boronic acid moiety was found to be a critical pharmacophore for enhanced in vitro potency against wild-type hepatitis C replicons and known clinical polymorphic and resistant HCV mutant replicons. The synthesis, optimization, and structure-activity relationships associated with inhibition of HCV replication in a subgenomic replication system for a series of non-nucleoside boron-containing HCV RNA-dependent RNA polymerase (NS5B) inhibitors are described. A summary of the discovery of 3 (GSK5852), a molecule which entered clinical trials in subjects infected with HCV in 2011, is included.


Assuntos
Antivirais/farmacologia , Ácidos Borônicos/química , Inibidores Enzimáticos/farmacologia , Hepacivirus/efeitos dos fármacos , RNA Polimerase Dependente de RNA/antagonistas & inibidores , Antivirais/química , Descoberta de Drogas , Farmacorresistência Viral/genética , Hepacivirus/enzimologia , Hepacivirus/genética , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Relação Estrutura-Atividade , Proteínas não Estruturais Virais/antagonistas & inibidores
14.
Chemistry ; 19(47): 15872-8, 2013 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-24127424

RESUMO

The twenty first amino acid, selenocysteine (Sec), is the only amino acid that is synthesized on its cognate transfer RNA (tRNA(Sec)) in all domains of life. The multistep pathway involves O-phosphoseryl-tRNA:selenocysteinyl-tRNA synthase (SepSecS), an enzyme that catalyzes the terminal chemical reaction during which the phosphoseryl-tRNA(Sec) intermediate is converted into selenocysteinyl-tRNA(Sec). The SepSecS architecture and the mode of tRNA(Sec) recognition have been recently determined at atomic resolution. The crystal structure provided valuable insights that gave rise to mechanistic proposals that could not be validated because of the lack of appropriate molecular probes. To further improve our understanding of the mechanism of the biosynthesis of selenocysteine in general and the mechanism of SepSecS in particular, stable tRNA(Sec) substrates carrying aminoacyl moieties that mimic particular reaction intermediates are needed. Here, we report on the accurate synthesis of methylated, phosphorylated, and phosphonated serinyl-derived tRNA(Sec) mimics that contain a hydrolysis-resistant ribose 3'-amide linkage instead of the natural ester bond. The procedures introduced allow for efficient site-specific methylation and/or phosphorylation directly on the solid support utilized in the automated RNA synthesis. For the preparation of (S)-2-amino-4-phosphonobutyric acid-oligoribonucleotide conjugates, a separate solid support was generated. Furthermore, we developed a three-strand enzymatic ligation protocol to obtain the corresponding full-length tRNA(Sec) derivatives. Finally, we developed an electrophoretic mobility shift assay (EMSA) for rapid, qualitative characterization of the SepSecS-tRNA interactions. The novel tRNA(Sec) mimics are promising candidates for further elucidation of the biosynthesis of selenocysteine by X-ray crystallography and other biochemical approaches, and could be attractive for similar studies on other tRNA-dependent enzymes.


Assuntos
Materiais Biocompatíveis/síntese química , Ácidos Fosforosos/química , RNA de Transferência Aminoácido-Específico/química , Aminobutiratos/química , Sequência de Bases , Materiais Biocompatíveis/química , Metilação , Conformação de Ácido Nucleico , Fosforilação , RNA de Transferência Aminoácido-Específico/síntese química , Técnicas de Síntese em Fase Sólida
15.
J Bacteriol ; 195(14): 3252-9, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23687267

RESUMO

The majority of outer membrane (OM) lipoproteins in Gram-negative bacteria are tethered to the membrane via an attached lipid moiety and oriented facing in toward the periplasmic space; a few lipoproteins have been shown to be surface exposed. The outer membrane lipoprotein P6 from the Gram-negative pathogenic bacterium nontypeable Haemophilus influenzae (NTHi) is surface exposed and a leading vaccine candidate for prevention of NTHi infections. However, we recently found that P6 is not a transmembrane protein as previously thought (L. V. Michel, B. Kalmeta, M. McCreary, J. Snyder, P. Craig, M. E. Pichichero, Vaccine 29:1624-1627, 2011). Here we pursued studies to show that P6 has a dual orientation, existing infrequently as surface exposed and predominantly as internally oriented toward the periplasmic space. Flow cytometry using three monoclonal antibodies with specificity for P6 showed surface staining of whole NTHi cells. Confocal microscopy imaging confirmed that antibodies targeted surface-exposed P6 of intact NTHi cells and not internal P6 in membrane-compromised or dead cells. Western blots of two wild-type NTHi strains and a mutant NTHi strain that does not express P6 showed that P6 antibodies do not detect a promiscuous epitope on NTHi. Depletion of targets to nonlipidated P6 significantly decreased bactericidal activity of human serum. Protease digestion of surface-exposed P6 demonstrated that P6 is predominantly internally localized in a manner similar to its homologue Pal in Escherichia coli. We conclude that P6 of NTHi is likely inserted into the OM in two distinct orientations, with the predominant orientation facing in toward the periplasm.


Assuntos
Proteínas da Membrana Bacteriana Externa/análise , Membrana Celular/química , Vacinas Anti-Haemophilus/análise , Haemophilus influenzae/química , Lipoproteínas/análise , Anticorpos Antibacterianos/metabolismo , Anticorpos Monoclonais/metabolismo , Western Blotting , Citometria de Fluxo , Microscopia Confocal , Coloração e Rotulagem
16.
Croat Med J ; 53(6): 535-50, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23275319

RESUMO

Selenocysteine, the 21st amino acid, has been found in 25 human selenoproteins and selenoenzymes important for fundamental cellular processes ranging from selenium homeostasis maintenance to the regulation of the overall metabolic rate. In all organisms that contain selenocysteine, both the synthesis of selenocysteine and its incorporation into a selenoprotein requires an elaborate synthetic and translational apparatus, which does not resemble the canonical enzymatic system employed for the 20 standard amino acids. In humans, three synthetic enzymes, a specialized elongation factor, an accessory protein factor, two catabolic enzymes, a tRNA, and a stem-loop structure in the selenoprotein mRNA are critical for ensuring that only selenocysteine is attached to selenocysteine tRNA and that only selenocysteine is inserted into the nascent polypeptide in response to a context-dependent UGA codon. The abnormal selenium homeostasis and mutations in selenoprotein genes have been causatively linked to a variety of human diseases, which, in turn, sparked a renewed interest in utilizing selenium as the dietary supplement to either prevent or remedy pathologic conditions. In contrast, the importance of the components of the selenocysteine-synthetic machinery for human health is less clear. Emerging evidence suggests that enzymes responsible for selenocysteine formation and decoding the selenocysteine UGA codon, which by extension are critical for synthesis of the entire selenoproteome, are essential for the development and health of the human organism.


Assuntos
Selenocisteína/biossíntese , Selenoproteínas/metabolismo , Saúde , Humanos , Selênio/metabolismo , Selenocisteína/fisiologia
18.
Am J Surg Pathol ; 33(6): 886-93, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19194279

RESUMO

Rarely, dysplasia in Barrett's esophagus (BE) is composed of crypts lined by cuboidal-shaped cells that contain a centrally located nucleus, markedly increased nuclear/cytoplasmic ratio, but without nuclear stratification characteristic of conventional "adenomatous" dysplasia. The aim of this study was to evaluate the clinical and pathologic features, natural history, and DNA content flow cytometric abnormalities of BE patients with non-adenomatous dysplasia (NAD) in a cohort of BE patients enrolled in a prospective surveillance program. Eighteen patients with NAD identified over a 6 year period, in a cohort of 270 consecutive patients with BE and without esophageal adenocarcinoma (EA) at baseline, were evaluated for clinical and pathologic features, including association with conventional adenomatous dysplasia and EA, DNA content flow cytometric abnormalities (tetraploidy and aneuploidy) and outcome, over a mean follow-up period of 4.1 years. The findings in the 18 study patients were compared to those in the 252 remaining (control) patients without NAD. Control patients included 228 with metaplasia/indefinite for dysplasia, and 24 with conventional adenomatous dysplasia (13 low-grade, 11 high-grade). The prevalence rate of NAD in our BE cohort was 6.7% Of the 18 study patients, there were 17 were males and 1 female of mean age 66.7 years. The mean length of BE was 3.9 cm NAD foci were associated with goblet or non-goblet epithelium in 62% and 38% of cases, respectively. Ninety-four percent of patients with NAD (17/18) also had conventional adenomatous dysplasia (four with low-grade, 13 with high-grade) elsewhere in the esophagus at the same endoscopic procedure as the one that detected NAD. Patients with NAD had a significantly shorter length of BE compared to control patients with conventional adenomatous dysplasia (N=24) (p=0.03). Patients with NAD also showed a significantly higher rate of DNA content flow cytometric abnormalities compared to the entire cohort of control patients (38% vs. 11%, p=0.05). However, no significant differences regarding either flow cytometric abnormalities or progression to EA were found when the NAD patients were compared only to the 24 controls with conventional adenomatous dysplasia. NAD is a high grade histologic variant of intraepithelial neoplasia that is episodic in nature, and shows a high association with conventional adenomatous high-grade dysplasia.


Assuntos
Esôfago de Barrett/genética , Esôfago de Barrett/patologia , Adenocarcinoma/epidemiologia , Adenocarcinoma/patologia , Idoso , Progressão da Doença , Neoplasias Esofágicas/epidemiologia , Neoplasias Esofágicas/patologia , Feminino , Citometria de Fluxo , Humanos , Masculino , Metaplasia/epidemiologia , Metaplasia/patologia , Prevalência , Fatores de Risco
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