Simpson's Paradox, Lord's Paradox, and Suppression Effects are the same phenomenon – the reversal paradox

This article discusses three statistical paradoxes that pervade epidemiological research: Simpson's paradox, Lord's paradox, and suppression. These paradoxes have important implications for the interpretation of evidence from observational studies. This article uses hypothetical scenarios to illustrate how the three paradoxes are different manifestations of one phenomenon – the reversal paradox – depending on whether the outcome and explanatory variables are categorical, continuous or a combination of both; this renders the issues and remedies for any one to be similar for all three. Although the three statistical paradoxes occur in different types of variables, they share the same characteristic: the association between two variables can be reversed, diminished, or enhanced when another variable is statistically controlled for. Understanding the concepts and theory behind these paradoxes provides insights into some controversial or contradictory research findings. These paradoxes show that prior knowledge and underlying causal theory play an important role in the statistical modelling of epidemiological data, where incorrect use of statistical models might produce consistent, replicable, yet erroneous results

T-Bet and Eomes Regulate the Balance between the Effector/Central Memory T Cells versus Memory Stem Like T Cells

Memory T cells are composed of effector, central, and memory stem cells. Previous studies have implicated that both T-bet and Eomes are involved in the generation of effector and central memory CD8 T cells. The exact role of these transcription factors in shaping the memory T cell pool is not well understood, particularly with memory stem T cells. Here, we demonstrate that both T-bet or Eomes are required for elimination of established tumors by adoptively transferred CD8 T cells. We also examined the role of T-bet and Eomes in the generation of tumor-specific memory T cell subsets upon adoptive transfer. We showed that combined T-bet and Eomes deficiency resulted in a severe reduction in the number of effector/central memory T cells but an increase in the percentage of CD62LhighCD44low Sca-1+ T cells which were similar to the phenotype of memory stem T cells. Despite preserving large numbers of phenotypic memory stem T cells, the lack of both of T-bet and Eomes resulted in a profound defect in antitumor memory responses, suggesting T-bet and Eomes are crucial for the antitumor function of these memory T cells. Our study establishes that T-bet and Eomes cooperate to promote the phenotype of effector/central memory CD8 T cell versus that of memory stem like T cells. © 2013 Li et al

Trastuzumab duocarmazine in locally advanced and metastatic solid tumours and HER2-expressing breast cancer: a phase 1 dose-escalation and dose-expansion study

Background: Trastuzumab duocarmazine is a novel HER2-targeting antibody-drug conjugate comprised of trastuzumab covalently bound to a linker drug containing duocarmycin. Preclinical studies showed promising antitumour activity in various models. In this first-in-human study, we assessed the safety and activity of trastuzumab duocarmazine in patients with advanced solid tumours. Methods: We did a phase 1 dose-escalation and dose-expansion study. The dose-escalation cohort comprised patients aged 18 years or older enrolled from three academic hospitals in Belgium, the Netherlands, and the UK with locally advanced or metastatic solid tumours with variable HER2 status who were refractory to standard cancer treatment. A separate cohort of patients were enrolled to the dose-expansion phase from 15 hospitals in Belgium, the Netherlands, Spain, and the UK. Dose-expansion cohorts included patients aged 18 years or older with breast, gastric, urothelial, or endometrial cancer with at least HER2 immunohistochemistry 1+ expression and measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST). Trastuzumab duocarmazine was administered intravenously on day 1 of each 3-week cycle. In the dose-escalation phase, trastuzumab duocarmazine was given at doses of 0.3 mg/kg to 2.4 mg/kg (3 + 3 design) until disease progression or unacceptable toxicity. The primary endpoint of the dose-escalation phase was to assess safety and ascertain the recommended phase 2 dose, which would be the dose used in the dose-expansion phase. The primary endpoint of the dose-expansion phase was the proportion of patients achieving an objective response (complete response or partial response), as assessed by the investigator using RECIST version 1.1. This ongoing study is registered with ClinicalTrials.gov, number NCT02277717, and is fully recruited. Findings: Between Oct 30, 2014, and April 2, 2018, 39 patients were enrolled and treated in the dose-escalation phase and 146 patients were enrolled and treated in the dose-expansion phase. One dose-limiting toxic effect (death from pneumonitis) occurred at the highest administered dose (2.4 mg/kg) in the dose-escalation phase. One further death occurred in the dose-escalation phase (1.5 mg/kg cohort) due to disease progression, which was attributed to general physical health decline. Grade 3-4 treatment-related adverse events reported more than once in the dose-escalation phase were keratitis (n=3) and fatigue (n=2). Based on all available data, the recommended phase 2 dose was set at 1.2 mg/kg. In the dose-expansion phase, treatment-related serious adverse events were reported in 16 (11%) of 146 patients, most commonly infusion-related reactions (two [1%]) and dyspnoea (two [1%]). The most common treatment-related adverse events (grades 1-4) were fatigue (48 [33%] of 146 patients), conjunctivitis (45 [31%]), and dry eye (45 [31%]). Most patients (104 [71%] of 146) had at least one ocular adverse event, with grade 3 events reported in ten (7%) of 146 patients. No patients died from treatment-related adverse events and four patients died due to disease progression, which were attributed to hepatic failure (n=1), upper gastrointestinal haemorrhage (n=1), neurological decompensation (n=1), and renal failure (n=1). In the breast cancer dose-expansion cohorts, 16 (33%, 95% CI 20.4-48.4) of 48 assessable patients with HER2-positive breast cancer achieved an objective response (all partial responses) according to RECIST. Nine (28%, 95% CI 13.8-46.8) of 32 patients with HER2-low, hormone receptor-positive breast cancer and six (40%, 16.3-67.6) of 15 patients with HER2-low, hormone receptor-negative breast cancer achieved an objective response (all partial responses). Partial responses were also observed in one (6%, 95% CI 0.2-30.2) of 16 patients with gastric cancer, four (25%, 7.3-52.4) of 16 patients with urothelial cancer, and five (39%, 13.9-68.4) of 13 patients with endometrial cancer. Interpretation: Trastuzumab duocarmazine shows notable clinical activity in heavily pretreated patients with HER2-expressing metastatic cancer, including HER2-positive trastuzumab emtansine-resistant and HER2-low breast cancer, with a manageable safety profile. Further investigation of trastuzumab duocarmazine for HER2-positive breast cancer is ongoing and trials for HER2-low breast cancer and other HER2-expressing cancers are in preparation. Copyright (C) 2019 Elsevier Ltd. All rights reserved

Interobserver variation in the classification of tumor deposits in rectal cancer-is the use of histopathological characteristics the way to go?

The focus on lymph node metastases (LNM) as the most important prognostic marker in colorectal cancer (CRC) has been challenged by the finding that other types of locoregional spread, including tumor deposits (TDs), extramural venous invasion (EMVI), and perineural invasion (PNI), also have significant impact. However, there are concerns about interobserver variation when differentiating between these features. Therefore, this study analyzed interobserver agreement between pathologists when assessing routine tumor nodules based on TNM 8. Electronic slides of 50 tumor nodules that were not treated with neoadjuvant therapy were reviewed by 8 gastrointestinal pathologists. They were asked to classify each nodule as TD, LNM, EMVI, or PNI, and to list which histological discriminatory features were present. There was overall agreement of 73.5% (κ 0.38, 95%-CI 0.33–0.43) if a nodal versus non-nodal classification was used, and 52.2% (κ 0.27, 95%-CI 0.23–0.31) if EMVI and PNI were classified separately. The interobserver agreement varied significantly between discriminatory features from κ 0.64 (95%-CI 0.58–0.70) for roundness to κ 0.26 (95%-CI 0.12–0.41) for a lone arteriole sign, and the presence of discriminatory features did not always correlate with the final classification. Since extranodal pathways of spread are prognostically relevant, classification of tumor nodules is important. There is currently no evidence for the prognostic relevance of the origin of TD, and although some histopathological characteristics showed good interobserver agreement, these are often non-specific. To optimize interobserver agreement, we recommend a binary classification of nodal versus extranodal tumor nodules which is based on prognostic evidence and yields good overall agreement

Interobserver variation in the classification of tumor deposits in rectal cancer – is the use of histopathological characteristics the way to go?

The focus on lymph node metastases (LNM) as the most important prognostic marker in colorectal cancer (CRC) has been challenged by the finding that other types of locoregional spread, including tumor deposits (TDs), extramural venous invasion (EMVI), and perineural invasion (PNI), also have significant impact. However, there are concerns about interobserver variation when differentiating between these features. Therefore, this study analyzed interobserver agreement between pathologists when assessing routine tumor nodules based on TNM 8. Electronic slides of 50 tumor nodules that were not treated with neoadjuvant therapy were reviewed by 8 gastrointestinal pathologists. They were asked to classify each nodule as TD, LNM, EMVI, or PNI, and to list which histological discriminatory features were present. There was overall agreement of 73.5% (κ 0.38, 95%-CI 0.33–0.43) if a nodal versus non-nodal classification was used, and 52.2% (κ 0.27, 95%-CI 0.23–0.31) if EMVI and PNI were classified separately. The interobserver agreement varied significantly between discriminatory features from κ 0.64 (95%-CI 0.58–0.70) for roundness to κ 0.26 (95%-CI 0.12–0.41) for a lone arteriole sign, and the presence of discriminatory features did not always correlate with the final classification. Since extranodal pathways of spread are prognostically relevant, classification of tumor nodules is important. There is currently no evidence for the prognostic relevance of the origin of TD, and although some histopathological characteristics showed good interobserver agreement, these are often non-specific. To optimize interobserver agreement, we recommend a binary classification of nodal versus extranodal tumor nodules which is based on prognostic evidence and yields good overall agreement

Towards enhancing national capacity for evidence informed policy and practice in falls management: a role for a "Translation Task Group"?

There has been a growing interest over recent years, both within Australia and overseas, in enhancing the translation of research into policy and practice. As one mechanism to improve the dissemination and uptake of falls research into policy and practice and to foster the development of policy-appropriate research, a Falls Translation Task Group has formed to facilitate linkage and exchange. There has been a growing interest over recent years, both within Australia and overseas, in enhancing the translation of research into policy and practice. As one mechanism to improve the dissemination and uptake of falls research into policy and practice and to foster the development of policy-appropriate research, a Falls Translation Task Group was formed as part of an NHMRC Population Health Capacity Building grant. This paper reports on the group\u27s first initiative to address issues around the research to policy and practice interface, and identifies a continuing role for such a group. MethodA one day forum brought together falls researchers and decision-makers from across the nation to facilitate linkage and exchange. Observations of the day\u27s proceedings were made by the authors. Participants were asked to complete a questionnaire at the commencement of the forum (to ascertain expectations) and at its completion (to evaluate the event). Observer notes and the questionnaire responses form the basis of analysis. Results: Both researchers and decision-makers have a desire to bridge the gap between research and policy and practice. Significant barriers to research uptake were highlighted and included both health system barriers (for example, a lack of financial and human resources) as well as evidence barriers (such as insufficient economic data and implementation research). Solutions to some of these barriers included the identification of clinical champions within the health sector to enhance evidence uptake, and the sourcing of alternative funding to support implementation research and encourage partnerships between researchers, decision-makers and other stakeholders. Conclusion: Participants sought opportunities for ongoing networking and collaboration. Two activities have been identified as priorities: establishing a policy-sensitive research agenda and partnering researchers and decision-makers in the process; and establishing a National Translation Task Group with a broad membership

Mechanism of nitrogen metabolism-related parameters and enzyme activities in the pathophysiology of autism

<p>Abstract</p> <p>Background</p> <p>There is evidence that impaired metabolism play an important role in the etiology of many neuropsychiatric disorders. Although this has not been investigated to date, several recent studies proposed that nitrogen metabolism-related parameters may have a pathophysiological role in autism.</p> <p>Methods</p> <p>The study enrolled 20 Saudi boys with autism aged 4 to 12 years and 20 healthy controls matched for age and gender. Levels of creatine, urea, ammonia, gamma-aminobutyric acid (GABA), glutamate:glutamine (Glu:Gln) ratio, and enzymatic activities of glutamate dehydrogenase, 5'-nucleotidase, and adenosine deaminase (ADA) were determined in plasma samples from both groups.</p> <p>Results</p> <p>We found a significant elevation of creatine, 5'-nucleotidase, GABA, and glutamic acid and a significant decrease in the enzymatic activity of ADA and glutamine level in patients with autism compared with healthy controls. The most significant variation between the two groups was found in the Glu:Gln ratio.</p> <p>Conclusion</p> <p>A raised Glu:Gln ratio together with positive correlations in creatine, GABA, and 5'-nucleotidase levels could contribute to the pathophysiology of autism, and might be useful diagnostic markers. The mechanism through which these parameters might be related to autism is discussed in detail.</p

Modeling of Electromagnetic NDE of Civil Structures

The inspection of civil structures, such as bridge decks, roadways and masonry is becoming an increasingly important area for the application of NDE methodologies. A variety of methods have been used for detecting flaws, cracks and voids as well as locating structural features such as reinforcing bars and tensioning cables. The large size of civil structures necessitates the use of an NDE technique that is capable of rapid inspection of large areas with good penetration. A candidate approach for such inspection is the microwave NDT method. Microwave energy penetrates dielectric materials such as those encountered in civil structures and consequently inspection can be accomplished using noncontact devices mounted on a fast scanning mechanism. The paper presents a numerical model for simulating electromagnetic scattering from two and three dimensional objects embedded in large structures. Such models are useful in the design and development of systems required for microwave imaging of civil structures.</p