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Thioredoxin reductase-1 (TrxR1)-, glutathione reductase (Gsr)-, and Nrf2 transcription factor-driven antioxidant systems form an integrated network that combats potentially carcinogenic oxidative damage yet also protects cancer cells from oxidative death. Here we show that although unchallenged wild-type (WT), TrxR1-null, or Gsr-null mouse livers exhibited similarly low DNA damage indices, these were 100-fold higher in unchallenged TrxR1/Gsr-double-null livers. Notwithstanding, spontaneous cancer rates remained surprisingly low in TrxR1/Gsr-null livers. All genotypes, including TrxR1/Gsr-null, were susceptible to N-diethylnitrosamine (DEN)-induced liver cancer, indicating that loss of these antioxidant systems did not prevent cancer cell survival. Interestingly, however, following DEN treatment, TrxR1-null livers developed threefold fewer tumors compared with WT livers. Disruption of TrxR1 in a marked subset of DEN-initiated cancer cells had no effect on their subsequent contributions to tumors, suggesting that TrxR1-disruption does not affect cancer progression under normal care, but does decrease the frequency of DEN-induced cancer initiation. Consistent with this idea, TrxR1-null livers showed altered basal and DEN-exposed metabolomic profiles compared with WT livers. To examine how oxidative stress influenced cancer progression, we compared DEN-induced cancer malignancy under chronically low oxidative stress (TrxR1-null, standard care) vs. elevated oxidative stress (TrxR1/Gsr-null livers, standard care or phenobarbital-exposed TrxR1-null livers). In both cases, elevated oxidative stress was correlated with significantly increased malignancy. Finally, although TrxR1-null and TrxR1/Gsr-null livers showed strong Nrf2 activity in noncancerous hepatocytes, there was no correlation between malignancy and Nrf2 expression within tumors across genotypes. We conclude that TrxR1, Gsr, Nrf2, and oxidative stress are major determinants of liver cancer but in a complex, context-dependent manner.
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Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Glutationa Redutase/metabolismo , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Estresse Oxidativo/fisiologia , Tiorredoxina Redutase 1/metabolismo , Animais , Antioxidantes/metabolismo , Dano ao DNA/fisiologia , Progressão da Doença , Regulação da Expressão Gênica/fisiologia , Glutationa/metabolismo , Hepatócitos/metabolismo , Fígado/metabolismo , Fígado/patologia , Masculino , Metaboloma/fisiologia , Camundongos , Fator 2 Relacionado a NF-E2/metabolismo , OxirreduçãoRESUMO
New densitometer installation requires cross-calibration for accurate longitudinal assessment. When replacing a unit with the same model, the International Society for Clinical Densitometry recommends cross-calibrating by scanning phantoms 10 times on each instrument and states that spine bone mineral density (BMD) should be within 1%, whereas total body lean, fat, and %fat mass should be within 2% of the prior instrument. However, there is limited validation that these recommendations provide adequate total body cross-calibration. Here, we report a total body cross-calibration experience with phantoms and humans. Cross-calibration between an existing and new Lunar iDXA was performed using 3 encapsulated spine phantoms (GE [GE Lunar, Madison, WI], BioClinica [BioClinica Inc, Princeton, NJ], and Hologic [Hologic Inc, Bedford, MA]), 1 total body composition phantom (BioClinica), and 30 human volunteers. Thirty scans of each phantom and a total body scan of human volunteers were obtained on each instrument. All spine phantom BMD means were similar (within 1%; <-0.010 g/cm2 bias) between the existing and new dual-energy X-ray absorptiometry unit. The BioClinica body composition phantom (BBCP) BMD and bone mineral content (BMC) values were within 2% with biases of 0.005 g/cm2 and -3.4 g. However, lean and fat mass and %fat differed by 4.6%-7.7% with biases of +463 g, -496 g, and -2.8%, respectively. In vivo comparison supported BBCP data; BMD and BMC were within â¼2%, but lean and fat mass and %fat differed from 1.6% to 4.9% with biases of +833 g, -860 g, and -1.1%. As all body composition comparisons exceeded the recommended 2%, the new densitometer was recalibrated. After recalibration, in vivo bias was lower (<0.05%) for lean and fat; -23 and -5 g, respectively. Similarly, BBCP lean and fat agreement improved. In conclusion, the BBCP behaves similarly, but not identical, to human in vivo measurements for densitometer cross-calibration. Spine phantoms, despite good BMD and BMC agreement, did not detect substantial lean and fat differences observed using BBCP and in vivo assessments. Consequently, spine phantoms are inadequate for dual-energy X-ray absorptiometry whole body composition cross-calibration.
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Composição Corporal , Densidade Óssea , Imagem Corporal Total , Absorciometria de Fóton/métodos , Absorciometria de Fóton/normas , Adulto , Calibragem , Feminino , Humanos , Masculino , Imagens de Fantasmas , Coluna Vertebral/diagnóstico por imagem , Imagem Corporal Total/instrumentação , Imagem Corporal Total/métodosRESUMO
Quantitative computed tomography (QCT) measurements have been used extensively to ascertain information about bone quality and density due to the 3-dimensional information provided and the ability to segment out trabecular and cortical bones. QCT imaging helps to improve our understanding of the role that each bone compartment plays in the pathogenesis and prognosis of fracture. This study was conducted to explore longitudinal changes in femoral neck (FN) cortical bone structure using both volumetric bone mineral density (vBMD) and cortical shell thickness assessments via QCT in a double-blind, randomized, multicenter clinical trial in postmenopausal women with type 2 diabetes mellitus. This study also examined whether treatment-associated changes in the cortical bone vBMD and thickness in femoral neck quadrants could be evaluated. Subjects were randomized to rosiglitazone (RSG) or metformin (MET) for 52 wk followed by 24 wk of open-label MET. A subset of 87 subjects underwent QCT scans of the hip at baseline, after 52 wk of double-blind treatment, and after 24 wk of treatment with MET using standard full-body computed tomography scanners. All scans were evaluated and analyzed centrally. Cortical vBMD at the FN was precisely segmented from trabecular bone and used to assess a possible therapeutic effect on this bone compartment. QCT analysis showed reductions in adjusted mean percentage change in vBMD and in absolute cortical thickness occurred with RSG treatment from baseline to week 52, whereas changes with MET were generally minimal. The reductions observed during RSG treatment for 1 yr appeared to partially reverse during the open-label MET phase from weeks 52 to 76. The femoral neck quadrant may provide utility as a potential endpoint in clinical trials for the understanding of the therapeutic effect of new entities on cortical bone vs trabecular bone; however, further clinical validation is needed. TRIAL REGISTRATION: The protocol (GSK study number AVD111179) was registered on ClinicalTrials.gov as NCT00679939.
Assuntos
Osso Cortical/diagnóstico por imagem , Diabetes Mellitus Tipo 2/tratamento farmacológico , Colo do Fêmur/diagnóstico por imagem , Hipoglicemiantes/uso terapêutico , Tiazolidinedionas/uso terapêutico , Tomografia Computadorizada por Raios X , Osso Cortical/efeitos dos fármacos , Diabetes Mellitus Tipo 2/diagnóstico por imagem , Diabetes Mellitus Tipo 2/fisiopatologia , Método Duplo-Cego , Feminino , Colo do Fêmur/efeitos dos fármacos , Fraturas Ósseas/diagnóstico , Humanos , Estudos Longitudinais , Pós-Menopausa , Fatores de Risco , RosiglitazonaRESUMO
OBJECTIVES: To evaluate if the mean smallest detectable change (SDC) of multiple time intervals using the Bland & Altman (B&A) levels of agreement (LoA) method is an appropriate surrogate for the generalisability analysis method for estimating the overall SDC of radiological progression in rheumatoid arthritis (RA) trials. Secondly, to compare the SDC based on 95% LoA with the SDC based on 80% LoA, and to investigate the association between SDC and baseline damage and progression. METHODS: Fifteen datasets from randomised controlled trials in RA were scored by 13 experienced readers as pairs according to the modified Sharp/van der Heijde method. The SDC using the 95% and 80% LoA and the generalisability methods was calculated. RESULTS: 21 295 radiographic time points from 7643 patients were included. The mean (range) SDC for the LoA and the generalisability methods was 3.1 (2.3-4.3) and 3.2 (2.3-4.6) units, respectively. The mean ± SD difference between the two methods was -0.13 ± 0.28. The mean SDC including all intervals (n=31) was 3.0 ± 0.7 for 95% LoA and 2.0 ± 0.4 for 80% LoA. No relationship was observed between baseline damage and the SDC, whereas the SDC increased with increasing radiological progression. CONCLUSIONS: The mean of the interval SDCs obtained by the simple LoA method is a valid surrogate for the SDC obtained by complex generalisability methods. The SDC depends on the level of radiographic progression rather than on the level of absolute damage. In addition, the use of an SDC based on 80% rather than on 95% LoA is proposed.
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Artrite Reumatoide/diagnóstico por imagem , Limite de Detecção , Análise de Variância , Artrite Reumatoide/terapia , Bases de Dados Factuais , Progressão da Doença , Humanos , Radiografia , Ensaios Clínicos Controlados Aleatórios como Assunto , Reprodutibilidade dos Testes , Resultado do TratamentoRESUMO
OBJECTIVE: To determine if inhibition of inducible nitric oxide synthase (iNOS) with cindunistat hydrochloride maleate slows progression of osteoarthritis (OA) METHODS: This 2-year, multinational, double-blind, placebo-controlled trial enrolled patients with symptomatic knee OA (Kellgren and Lawrence Grade (KLG) 2 or 3). Standard OA therapies were permitted throughout. Patients were randomly assigned to cindunistat (50 or 200 mg/day) or placebo. Randomisation was stratified by KLG. Radiographs to assess joint space narrowing (JSN) were acquired using the modified Lyon-schuss protocol at baseline, week 48 and 96. RESULTS: Of 1457 patients (50 mg/day, n=485; 200 mg/day, n=486; placebo, n=486), 1048 (71.9%) completed the study. Patients were predominantly women; 56% had KLG3. The primary analysis did not demonstrate superiority of cindunistat versus placebo for rate of change in JSN. In KLG2 patients, JSN after 48 weeks was lower with cindunistat 50 mg/day versus placebo (p=0.032). Least-squares mean±SE JSN with cindunistat 50 mg/day ( -0.048±0.028 mm) and 200 mg/day (-0.062±0.028 mm) were 59.9% (95% CI 6.8% to 106.9%) and 48.7% (95% CI -8.4% to 93.9%) of placebo, improvement was not maintained at 96 weeks. No improvement was observed for KLG3 patients at either time-point. Cindunistat did not improve joint pain or function, but was generally well tolerated. CONCLUSIONS: Cindunistat (50 or 200 mg/day) did not slow the rate of JSN versus placebo. After 48-weeks, KLG2 patients showed less JSN; however, the improvement was not sustained at 96-weeks. iNOS inhibition did not slow OA progression in KLG3 patients. CLINICAL TRIAL LISTING: NCT00565812.
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Amidinas/uso terapêutico , Cisteína/análogos & derivados , Inibidores Enzimáticos/uso terapêutico , Óxido Nítrico Sintase Tipo II/antagonistas & inibidores , Osteoartrite do Joelho/tratamento farmacológico , Adulto , Idoso , Idoso de 80 Anos ou mais , Cisteína/uso terapêutico , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Osteoartrite do Joelho/diagnóstico por imagem , Placebos , Radiografia , Resultado do TratamentoRESUMO
OBJECTIVE: The aim of this study is to provide data on the adjudication rate for a predetermined threshold of difference in change score between two readers in randomized controlled trials (RCTs). METHODS: Fifteen datasets from RCTs in RA were scored by 13 experienced readers as pairs according to the modified Sharp-van der Heijde method. The theoretical adjudication rates for thresholds of between 3 and 20 units were calculated. We investigated the influence of the number of time points within the same session, the length of the interval and disease duration on the adjudication rates. RESULTS: A total of 21,295 time points from 7643 patients from 15 databases were included in the analysis. The adjudication rate was inversely related to the threshold. Higher adjudication rates were observed with a higher number of time points, longer time intervals and in early versus established RA. The adjudication rates ranged from 0% to 22% depending on the scenario. CONCLUSION: With trained and experienced readers, the adjudication rate in RA RCTs is low even with very conservative adjudication thresholds.
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Artrite Reumatoide/diagnóstico por imagem , Progressão da Doença , Ensaios Clínicos Controlados Aleatórios como Assunto/estatística & dados numéricos , Adulto , Artrografia/métodos , Bases de Dados Factuais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Reumatologia/legislação & jurisprudência , Índice de Gravidade de DoençaRESUMO
Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is known to contain an active-site cysteine residue undergoing oxidation in response to hydrogen peroxide, leading to rapid inactivation of the enzyme. Here we show that human and mouse cells expressing a GAPDH mutant lacking this redox switch retain catalytic activity but are unable to stimulate the oxidative pentose phosphate pathway and enhance their reductive capacity. Specifically, we find that anchorage-independent growth of cells and spheroids is limited by an elevation of endogenous peroxide levels and is largely dependent on a functional GAPDH redox switch. Likewise, tumour growth in vivo is limited by peroxide stress and suppressed when the GAPDH redox switch is disabled in tumour cells. The induction of additional intratumoural oxidative stress by chemo- or radiotherapy synergized with the deactivation of the GAPDH redox switch. Mice lacking the GAPDH redox switch exhibit altered fatty acid metabolism in kidney and heart, apparently in compensation for the lack of the redox switch. Together, our findings demonstrate the physiological and pathophysiological relevance of oxidative GAPDH inactivation in mammals.
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Cisteína , Gliceraldeído-3-Fosfato Desidrogenases , Humanos , Animais , Camundongos , Gliceraldeído-3-Fosfato Desidrogenases/genética , Gliceraldeído-3-Fosfato Desidrogenases/química , Gliceraldeído-3-Fosfato Desidrogenases/metabolismo , Oxirredução , Cisteína/metabolismo , Estresse Oxidativo , Peróxido de Hidrogênio/farmacologia , Mamíferos/metabolismoRESUMO
BACKGROUND AND AIMS: Cholestatic liver diseases, including primary sclerosing cholangitis, are characterized by periportal inflammation with progression to hepatic fibrosis and ultimately cirrhosis. We recently reported that the thioredoxin antioxidant response is dysregulated during primary sclerosing cholangitis. The objective of this study was to examine the impact of genetic and pharmacological targeting of thioredoxin reductase 1 (TrxR1) on hepatic inflammation and liver injury during acute cholestatic injury. APPROACH AND RESULTS: Primary mouse hepatocytes and intrahepatic macrophages were isolated from 3-day bile duct ligated (BDL) mice and controls. Using wildtype and mice with a liver-specific deletion of TrxR1 (TrxR1LKO), we analyzed the effect of inhibition or ablation of TrxR1 signaling on liver injury and inflammation. Immunohistochemical analysis of livers from BDL mice and human cholestatic patients revealed increased TrxR1 staining in periportal macrophages and hepatocytes surrounding fibrosis. qPCR analysis of primary hepatocytes and intrahepatic macrophages revealed increased TrxR1 mRNA expression following BDL. Compared with sham controls, BDL mice exhibited increased inflammation, necrosis, and increased mRNA expression of pro-inflammatory cytokines, fibrogenesis, the NLRP3 inflammatory complex, and increased activation of NFkB, all of which were ameliorated in TrxR1LKO mice. Importantly, following BDL, TrxR1LKO induced periportal hepatocyte expression of Nrf2-dependent antioxidant proteins and increased mRNA expression of basolateral bile acid transporters with reduced expression of bile acid synthesis genes. In the acute BDL model, the TrxR1 inhibitor auranofin (10 mg/kg/1 d preincubation, 3 d BDL) ameliorated BDL-dependent increases in Nlrp3, GsdmD, Il1ß, and TNFα mRNA expression despite increasing serum alanine aminotransferase, aspartate aminotransferase, bile acids, and bilirubin. CONCLUSIONS: These data implicate TrxR1-signaling as an important regulator of inflammation and bile acid homeostasis in cholestatic liver injury.
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Colangite Esclerosante , Colestase , Animais , Humanos , Camundongos , Antioxidantes , Ácidos e Sais Biliares , Inflamação , Cirrose Hepática/genética , Cirrose Hepática/metabolismo , Ativação de Macrófagos , Proteína 3 que Contém Domínio de Pirina da Família NLR , RNA Mensageiro , Tiorredoxina Redutase 1/genéticaRESUMO
Inflammatory cholestatic liver diseases, including Primary Sclerosing Cholangitis (PSC), are characterized by periportal inflammation with progression to cirrhosis. The objective of this study was to examine interactions between oxidative stress and autophagy in cholestasis. Using hepatic tissue from male acute cholestatic (bile duct ligated) as well as chronic cholestatic (Mdr2KO) mice, localization of oxidative stress, the antioxidant response and induction of autophagy were analyzed and compared to human PSC liver. Concurrently, the ability of reactive aldehydes to post-translationally modify the autophagosome marker p62 was assessed in PSC liver tissue and in cell culture. Expression of autophagy markers was upregulated in human and mouse cholestatic liver. Whereas mRNA expression of Atg12, Lamp1, Sqstm1 and Map1lc3 was increased in acute cholestasis in mice, it was either suppressed or not significantly changed in chronic cholestasis. In human and murine cholestasis, periportal hepatocytes showed increased IHC staining of ubiquitin, 4-HNE, p62, and selected antioxidant proteins. Increased p62 staining colocalized with accumulation of 4-HNE-modified proteins in periportal parenchymal cells as well as with periportal macrophages in both human and mouse liver. Mechanistically, p62 was identified as a direct target of lipid aldehyde adduction in PSC hepatic tissue and in vitro cell culture. In vitro LS-MS/MS analysis of 4-HNE treated recombinant p62 identified carbonylation of His123, Cys128, His174, His181, Lys238, Cys290, His340, Lys341 and His385. These data indicate that dysregulation of autophagy and oxidative stress/protein damage are present in the same periportal hepatocyte compartment of both human and murine cholestasis. Thus, our results suggest that both increased expression as well as ineffective autophagic degradation of oxidatively-modified proteins contributes to injury in periportal parenchymal cells and that direct modification of p62 by reactive aldehydes may contribute to autophagic dysfunction.
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Antioxidantes , Colestase , Humanos , Camundongos , Masculino , Animais , Antioxidantes/metabolismo , Aldeídos/metabolismo , Espectrometria de Massas em Tandem , Colestase/metabolismo , Fígado/metabolismo , Autofagia , Cirrose Hepática/patologiaRESUMO
68Ga-satoreotide trizoxetan is a novel somatostatin receptor antagonist associated with high sensitivity and reproducibility in neuroendocrine tumor (NET) detection and localization. However, the optimal peptide mass and radioactivity ranges for 68Ga-satoreotide trizoxetan have not yet been established. We therefore aimed to determine its optimal dosing regimen in patients with metastatic gastroenteropancreatic NETs in a prospective, randomized, 2 × 3 factorial, multicenter phase II study. Methods: Patients received 68Ga-satoreotide trizoxetan at a peptide mass of 5-20 µg on day 1 of the study and of 30-45 µg on days 16-22, at 1 of 3 68Ga radioactivity ranges (40-80, 100-140, or 160-200 MBq). Whole-body PET/CT imaging was performed 50-70 min after each injection. The primary endpoint was the detection rate of NET lesions imaged by 68Ga-satoreotide trizoxetan relative to contrast-enhanced CT (for each of the 6 peptide mass and radioactivity range combinations). Results: Twenty-four patients were evaluated in the per-protocol analysis. The median number of lesions detected by 68Ga-satoreotide trizoxetan PET/CT or PET alone was at least twice as high as the number detected by contrast-enhanced CT across the 6 studied peptide mass and radioactivity range combinations. There were no differences between the 2 peptide mass ranges or between the 3 radioactivity ranges in the number of identified lesions. However, a trend toward a lower relative lesion count was noted in the liver for the 40- to 80-MBq range. No relationship was observed between the radioactivity range per patient's body weight (MBq/kg) and the number of lesions detected by 68Ga-satoreotide trizoxetan. The median diagnostic sensitivity of 68Ga-satoreotide trizoxetan PET/CT, based on the number of lesions per patient, ranged from 85% to 87% across the different peptide mass and radioactivity ranges. Almost all reported adverse events were mild and self-limiting. Conclusion: A radioactivity of 100-200 MBq with a peptide mass of up to 50 µg was confirmed as the optimal dosing regimen for 68Ga-satoreotide trizoxetan to be used in future phase III studies.
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Tumores Neuroendócrinos , Compostos Organometálicos , Radioisótopos de Gálio , Humanos , Neoplasias Intestinais , Tumores Neuroendócrinos/patologia , Octreotida , Compostos Organometálicos/efeitos adversos , Neoplasias Pancreáticas , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Estudos Prospectivos , Compostos Radiofarmacêuticos , Reprodutibilidade dos Testes , Neoplasias GástricasRESUMO
UNLABELLED: Quantitative imaging biomarkers could speed the development of new treatments for unmet medical needs and improve routine clinical care. However, it is not clear how the various regulatory and nonregulatory (eg, reimbursement) processes (often referred to as pathways) relate, nor is it clear which data need to be collected to support these different pathways most efficiently, given the time- and cost-intensive nature of doing so. The purpose of this article is to describe current thinking regarding these pathways emerging from diverse stakeholders interested and active in the definition, validation, and qualification of quantitative imaging biomarkers and to propose processes to facilitate the development and use of quantitative imaging biomarkers. A flexible framework is described that may be adapted for each imaging application, providing mechanisms that can be used to develop, assess, and evaluate relevant biomarkers. From this framework, processes can be mapped that would be applicable to both imaging product development and to quantitative imaging biomarker development aimed at increasing the effectiveness and availability of quantitative imaging. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100800/-/DC1.
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Biomarcadores , Diagnóstico por Imagem , Difusão de Inovações , Avaliação da Tecnologia Biomédica/normas , Pesquisa Biomédica/organização & administração , Conflito de Interesses , Aprovação de Equipamentos , Europa (Continente) , Humanos , Valor Preditivo dos Testes , Estados Unidos , United States Food and Drug AdministrationRESUMO
BACKGROUND: 68Ga-satoreotide trizoxetan is a novel somatostatin receptor antagonist exhibiting higher tumour-to-background ratios and sensitivity compared to 68Ga-DOTATOC. This randomised, 2 × 3 factorial, phase II study aimed to confirm the optimal peptide mass and radioactivity ranges for 68Ga-satoreotide trizoxetan, using binary visual reading. To that end, 24 patients with metastatic gastroenteropancreatic neuroendocrine tumours received 5-20 µg of 68Ga-satoreotide trizoxetan on day 1 of the study and 30-45 µg on day 16-22, with one of three gallium-68 radioactivity ranges (40-80, 100-140, or 160-200 MBq) per visit. Two 68Ga-satoreotide trizoxetan PET/CT scans were acquired from each patient post-injection, and were scored by experienced independent blinded readers using a binary system (0 for non-optimal image quality and 1 for optimal image quality). For each patient pair of 68Ga-satoreotide trizoxetan scans, one or both images could score 1. RESULTS: Total image quality score for 68Ga-satoreotide trizoxetan PET scans was lower in the 40-80 MBq radioactivity range (56.3%) compared to 100-140 MBq (90.6%) and 160-200 MBq (81.3%). Both qualitative and semi-quantitative analysis showed that peptide mass (5-20 or 30-45 µg) did not influence 68Ga-satoreotide trizoxetan imaging. There was only one reading where readers diverged on scoring; one reader preferred one image because of higher lesion conspicuity, and the other reader preferred the alternative image because of the ability to identify more lesions. CONCLUSIONS: Binary visual reading, which was associated with a low inter-reader variability, has further supported that the optimal administered radioactivity of 68Ga-satoreotide trizoxetan was 100-200 MBq with a peptide mass up to 50 µg. Trial registration ClinicalTrials.gov, NCT03220217. Registered 18 July 2017, https://clinicaltrials.gov/ct2/show/NCT03220217.
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The debate over human visual perception and how medical images should be interpreted have persisted since X-rays were the only imaging technique available. Concerns over rates of disagreement between expert image readers are associated with much of the clinical research and at times driven by the belief that any image endpoint variability is problematic. The deeper understanding of the reasons, value, and risk of disagreement are somewhat siloed, leading, at times, to costly and risky approaches, especially in clinical trials. Although artificial intelligence promises some relief from mistakes, its routine application for assessing tumors within cancer trials is still an aspiration. Our consortium of international experts in medical imaging for drug development research, the Pharma Imaging Network for Therapeutics and Diagnostics (PINTAD), tapped the collective knowledge of its members to ground expectations, summarize common reasons for reader discordance, identify what factors can be controlled and which actions are likely to be effective in reducing discordance. Reinforced by an exhaustive literature review, our work defines the forces that shape reader variability. This review article aims to produce a singular authoritative resource outlining reader performance's practical realities within cancer trials, whether they occur within a clinical or an independent central review.
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Inteligência Artificial , Radiologistas , HumanosRESUMO
Though many clinical trials rely on medical image evaluations for primary or key secondary endpoints, the methods to monitor reader performance are all too often mired in the legacy use of adjudication rates. If misused, this simple metric can be misleading and sometimes entirely contradictory. Furthermore, attempts to overcome the limitations of adjudication rates using de novo or ad hoc methods often ignore well-established research conducted over the last half-century and can lead to inaccurate conclusions or variable interpretations. Underperforming readers can be missed, expert readers retrained, or worse, replaced. This paper aims to standardize reader performance evaluations using proven statistical methods. Additionally, these methods will describe how to discriminate between scenarios of concern and normal medical interpretation variability. Statistical methods are provided for inter-reader and intra-reader variability and bias, including the adjudicator's bias. Finally, we have compiled guidelines for calculating correct sample sizes, considerations for intra-reader memory recall, and applying alternative designs for independent readers.
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Radiologistas , Humanos , Variações Dependentes do Observador , Reprodutibilidade dos TestesRESUMO
Cellular oxidants are primarily managed by the thioredoxin reductase-1 (TrxR1)- and glutathione reductase (Gsr)-driven antioxidant systems. In mice having hepatocyte-specific co-disruption of TrxR1 and Gsr (TrxR1/Gsr-null livers), methionine catabolism sustains hepatic levels of reduced glutathione (GSH). Although most mice with TrxR1/Gsr-null livers exhibit long-term survival, ~25% die from spontaneous liver failure between 4- and 7-weeks of age. Here we tested whether liver failure was ameliorated by ascorbate supplementation. Following ascorbate, dehydroascorbate, or mock treatment, we assessed survival, liver histology, or hepatic redox markers including GSH and GSSG, redox enzyme activities, and oxidative damage markers. Unexpectedly, rather than providing protection, ascorbate (5 mg/mL, drinking water) increased the death-rate to 43%. In adults, ascorbate (4 mg/g × 3 days i.p.) caused hepatocyte necrosis and loss of hepatic GSH in TrxR1/Gsr-null livers but not in wildtype controls. Dehydroascorbate (0.3 mg/g i.p.) also depleted hepatic GSH in TrxR1/Gsr-null livers, whereas GSH levels were not significantly affected by either treatment in wildtype livers. Curiously, however, despite depleting GSH, ascorbate treatment diminished basal DNA damage and oxidative stress markers in TrxR1/Gsr-null livers. This suggests that, although ascorbate supplementation can prevent oxidative damage, it also can deplete GSH and compromise already stressed livers.
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Significance: In humans, imbalances in the reduction-oxidation (redox) status of cells are associated with many pathological states. In addition, many therapeutics and prophylactics used as interventions for diverse pathologies either directly modulate oxidant levels or otherwise influence endogenous cellular redox systems. Recent Advances: The cellular machineries that maintain redox homeostasis or that function within antioxidant defense systems rely heavily on the regulated reactivities of sulfur atoms either within or derived from the amino acids cysteine and methionine. Recent advances have substantially advanced our understanding of the complex and essential chemistry of biological sulfur-containing molecules. Critical Issues: The redox machineries that maintain cellular homeostasis under diverse stresses can consume large amounts of energy to generate reducing power and/or large amounts of sulfur-containing nutrients to replenish or sustain intracellular stores. By understanding the metabolic pathways underlying these responses, one can better predict how to protect cells from specific stresses. Future Directions: Here, we summarize the current state of knowledge about the impacts of different stresses on cellular metabolism of sulfur-containing molecules. This analysis suggests that there remains more to be learned about how cells use sulfur chemistry to respond to stresses, which could in turn lead to advances in therapeutic interventions for some exposures or conditions.
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Redes e Vias Metabólicas , Estresse Fisiológico , Enxofre/metabolismo , Antioxidantes/metabolismo , Transformação Celular Neoplásica , Cisteína/metabolismo , Suscetibilidade a Doenças , Homeostase , Humanos , Metionina/metabolismo , Oxirredução , Estresse OxidativoRESUMO
Intermediary metabolism and detoxification place high demands on the disulfide reductase systems in most hepatocyte subcellular compartments. Biosynthetic, metabolic, cytoprotective and signalling activities in the cytosol; regulation of transcription in nuclei; respiration in mitochondria; and protein folding in endoplasmic reticulum all require resident disulfide reductase activities. In the cytosol, two NADPH-dependent enzymes, glutathione reductase and thioredoxin reductase, as well as a recently identified NADPH-independent system that uses catabolism of methionine to maintain pools of reduced glutathione, supply disulfide reducing power. However the necessary discontinuity between the cytosol and the interior of organelles restricts the ability of the cytosolic systems to support needs in other compartments. Maintenance of molecular- and charge-gradients across the inner-mitochondrial membrane, which is needed for oxidative phosphorylation, mandates that the matrix maintain an autonomous set of NADPH-dependent disulfide reductase systems. Elsewhere, complex mechanisms mediate the transfer of cytosolic reducing power into specific compartments. The redox needs in each compartment also differ, with the lumen of the endoplasmic reticulum, the mitochondrial inter-membrane space and some signalling proteins in the cytosol each requiring different levels of protein oxidation. Here, we present an overview of the current understanding of the disulfide reductase systems in major subcellular compartments of hepatocytes, integrating knowledge obtained from direct analyses on liver with inferences from other model systems. Additionally, we discuss relevant advances in the expanding field of redox signalling. LINKED ARTICLES: This article is part of a themed section on Chemical Biology of Reactive Sulfur Species. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.4/issuetoc.
Assuntos
Dissulfetos/metabolismo , Fígado/metabolismo , Oxirredutases/metabolismo , Animais , Humanos , NADP/metabolismo , Organelas/metabolismo , Oxirredução , Frações Subcelulares/metabolismoRESUMO
Over the past seven decades, research on autotrophic and heterotrophic model organisms has defined how the flow of electrons ("reducing power") from high-energy inorganic sources, through biological systems, to low-energy inorganic products like water, powers all of Life's processes. Universally, an initial major biological recipient of these electrons is nicotinamide adenine dinucleotide-phosphate, which thereby transits from an oxidized state (NADP+) to a reduced state (NADPH). A portion of this reducing power is then distributed via the cellular NADPH-dependent disulfide reductase systems as sequential reductions of disulfide bonds. Along the disulfide reduction pathways, some enzymes have active sites that use the selenium-containing amino acid, selenocysteine, in place of the common but less reactive sulfur-containing cysteine. In particular, the mammalian/metazoan thioredoxin systems are usually selenium-dependent as, across metazoan phyla, most thioredoxin reductases are selenoproteins. Among the roles of the NADPH-dependent disulfide reductase systems, the most universal is that they provide the reducing power for the production of DNA precursors by ribonucleotide reductase (RNR). Some studies, however, have uncovered examples of NADPH-independent disulfide reductase systems that can also support RNR. These systems are summarized here and their implications are discussed.
Assuntos
NADH NADPH Oxirredutases/metabolismo , NADP/metabolismo , Ribonucleotídeo Redutases/metabolismo , Animais , Humanos , OxirreduçãoRESUMO
OBJECTIVE: Nerve growth factor antibodies (NGF-ab) have shown promising analgesic efficacy. Aim was to describe reader training efforts and present reliability data focusing on radiographic eligibility in the tanezumab program. METHODS: A multi-step process was used for reader calibration and reliability testing. First, a reference standard set of cases was created and diagnostic performance was evaluated. A second exercise focused on agreement of ordinal assessment (Kellgren-Lawrence grading) of radiographic osteoarthritis. Subsequently, 11 readers were trained and read a test set of 100 cases focused on eligibility assessments. Additional reliability testing and calibration of five core readers assessing eligibility of 30 cases was performed 3 and 6 months after study start. RESULTS: Sensitivity for the reference standard readings ranged from 0.50 to 0.90 and specificity from 0.40 to 0.83. Overall agreement for Kellgren-Lawrence grading ranged from 71.4% to 82.9%. For the 11 reader exercise, in 76% of cases at least 8 of 11 readers agreed on eligibility status. For the reliability testing 3 months after study start, in 80.0% of cases at least 4 of 5 readers agreed on eligibility with a κ = 0.43 (95% CI: 0.32-0.54). For the reliability testing after 6 months, in 83.3% of cases at least 4 of 5 readers agreed on eligibility with a κ = 0.52 (95% CI: 0.41-0.63). CONCLUSIONS: After intense efforts spent in the development of an imaging program for an NGF-ab clinical program, the achieved reliability for eligibility assessment is substantial but not perfect. Ongoing efforts of calibration prior to including additional readers to the program and during study conduct between current readers will be needed to ensure agreement on potential adverse events and radiographic disease severity.
Assuntos
Ensaios Clínicos como Assunto , Osteoartrite/diagnóstico por imagem , Radiografia/normas , Analgésicos/uso terapêutico , Anticorpos Monoclonais Humanizados/uso terapêutico , Humanos , Variações Dependentes do Observador , Osteoartrite/tratamento farmacológico , Osteonecrose/diagnóstico por imagem , Seleção de Pacientes , Padrões de Referência , Reprodutibilidade dos Testes , Índice de Gravidade de DoençaRESUMO
Energetic nutrients are oxidized to sustain high intracellular NADPH/NADP+ ratios. NADPH-dependent reduction of thioredoxin-1 (Trx1) disulfide and glutathione disulfide by thioredoxin reductase-1 (TrxR1) and glutathione reductase (Gsr), respectively, fuels antioxidant systems and deoxyribonucleotide synthesis. Mouse livers lacking both TrxR1 and Gsr sustain these essential activities using an NADPH-independent methionine-consuming pathway; however, it remains unclear how this reducing power is distributed. Here, we show that liver-specific co-disruption of the genes encoding Trx1, TrxR1, and Gsr (triple-null) causes dramatic hepatocyte hyperproliferation. Thus, even in the absence of Trx1, methionine-fueled glutathione production supports hepatocyte S phase deoxyribonucleotide production. Also, Trx1 in the absence of TrxR1 provides a survival advantage to cells under hyperglycemic stress, suggesting that glutathione, likely via glutaredoxins, can reduce Trx1 disulfide in vivo. In triple-null livers like in many cancers, deoxyribonucleotide synthesis places a critical yet relatively low-volume demand on these reductase systems, thereby favoring high hepatocyte turnover over sustained hepatocyte integrity.