Statistical methods for assays with limits of detection: Serum bile acid as a differentiator between patients with normal colons, adenomas, and colorectal cancer

In analytic chemistry a detection limit (DL) is the lowest measurable amount of an analyte that can be distinguished from a blank; many biomedical measurement technologies exhibit this property. From a statistical perspective, these data present inferential challenges because instead of precise measures, one only has information that the value is somewhere between 0 and the DL (below detection limit, BDL). Substitution of BDL values, with 0 or the DL can lead to biased parameter estimates and a loss of statistical power. Statistical methods that make adjustments when dealing with these types of data, often called left-censored data, are available in many commercial statistical packages. Despite this availability, the use of these methods is still not widespread in biomedical literature. We have reviewed the statistical approaches of dealing with BDL values, and used simulations to examine the performance of the commonly used substitution methods and the most widely available statistical methods. We have illustrated these methods using a study undertaken at the Vanderbilt-Ingram Cancer Center, to examine the serum bile acid levels in patients with colorectal cancer and adenoma. We have found that the modern methods for BDL values identify disease-related differences that are often missed, with statistically naive approaches

Delayed viral clearance despite high number of activated T cells during the acute phase in Argentinean patients with hantavirus pulmonary syndrome

Background: The hallmarks of HPS are increase of vascular permeability and endothelial dysfunction. Although an exacerbated immune response is thought to be implicated in pathogenesis, clear evidence is still elusive. As orthohantaviruses are not cytopathic CD8+ T cells are believed to be the central players involved in pathogenesis. Methods: Serum and blood samples from Argentinean HPS patients were collected from 2014 to 2019. Routine white blood cell analyses, quantification and characterization of T-cell phenotypic profile, viral load, neutralizing antibody response and quantification of inflammatory mediators were performed. Findings: High numbers of activated CD4+ and CD8+ T cells were found in all HPS cases independently of disease severity. We found increased levels of some proinflammatory mediators during the acute phase of illness. Nonetheless, viral RNA remained high, showing a delay in clearance from blood up to late convalescence, when titers of neutralizing antibodies reached a high level. Interpretation: The high activated phenotypic profile of T cells seems to be unable to resolve infection during the acute and early convalescent phases, and it was not associated with the severity of the disease. Thus, at least part of the activated T cells could be induced by the dysregulated inflammatory response in an unspecific manner. Viral clearance seems to have been more related to high titers of neutralizing antibodies than to the T-cell response. Funding: This work was supported mainly by the Administración Nacional de Laboratorios e Institutos de Salud (ANLIS) “Dr. Carlos Malbrán”. Further details of fundings sources is included in the appendix.Fil: Iglesias, Ayelén Aluminé. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; ArgentinaFil: Periolo, Natalia. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bellomo, Carla María. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; ArgentinaFil: Lewis, Lorena Cecilia. Provincia del Chubut. Servicio de Salud Mental. Hospital Zonal de Esquel; ArgentinaFil: Olivera, Camila Paula. Provincia del Chubut. Servicio de Salud Mental. Hospital Zonal de Esquel; ArgentinaFil: Rosario Anselmo, Constanza. Provincia del Chubut. Servicio de Salud Mental. Hospital Zonal de Esquel; ArgentinaFil: García, Marina. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Coelho, Rocío María. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; ArgentinaFil: Alonso, Daniel Oscar. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; ArgentinaFil: Dighero Kemp, Bonnie. National Institute Of Allergy And Infectious Diseases; Estados UnidosFil: Sharma, Heema. National Institute Of Allergy And Infectious Diseases; Estados UnidosFil: Kuhn, Jens H.. National Institute Of Allergy And Infectious Diseases; Estados UnidosFil: Di Paola, Nicholas. Center For Genome Sciences, U.s. Army Medical Research; Estados UnidosFil: Sanchez Lockhart, Mariano. Center For Genome Sciences, U.s. Army Medical Research; Estados UnidosFil: Palacios, Gustavo. Center For Genome Sciences, U.s. Army Medical Research; Estados UnidosFil: Schierloh, Luis Pablo. Universidad Nacional de Entre Ríos. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigación y Desarrollo en Bioingeniería y Bioinformática; ArgentinaFil: Martinez, Valeria Paula. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentin

Dual blockade of the EGFR and COX-2 pathways: A phase II trial of cetuximab and celecoxib in patients with chemotherapy refractory metastatic colorectal cancer

OBJECTIVES: The epidermal growth factor receptor and cyclooxygenase-2 pathways play key and often complementary roles in the pathogenesis of colorectal cancer (CRC). This study explores the clinical and biological effects of combined blockade of these pathways METHODS: Cetuximab-naive patients with refractory CRC were treated with cetuximab (400 mg/m(2) loading dose followed by weekly cetuximab at 250 mg/m(2)) and celecoxib (200 mg orally twice daily). Urinary PGE-M, a stable metabolite of PGE-2 that correlates with in vivo COX-2 activity, and serum TGF-α, a ligand that binds to EGFR, were measured serially to assess the biological effect of COX-2 and EGFR blockade. RESULTS: Seventeen patients accrued on this study. Of the thirteen patients evaluable for response, there were two (15.4%) with confirmed partial responses, 4 (30.8%) with stable disease, and 7 (53.8%) with progressive disease. The median PFS for all evaluable patients was 55 days (95% CI [45, 112]; range 10-295 days). This study was terminated early due to lack of sufficient clinical activity. There were no statistically significant differences in serum TGF-α or urinary PGE-M between cycles in responders or nonresponders. CONCLUSIONS: This regimen resulted in response rates similar to those published for cetuximab monotherapy in patients with recurrent CRC. Aside from a higher than expected rate of infusion reactions, no other unexpected toxicities were observed. No differences in serum TGF-α or urinary PGE-M between cycles were seen, suggesting that the appropriate targets may not have been hit

Cognitive status, brain amyloid pathology, and neurodegeneration are associated with altered white matter microstructure

Background Brain amyloid (AB) and neurodegeneration (assessed using PET and MRI) are key AD pathology biomarkers, particularly during transitions from cognitively unimpaired (CU) to cognitively impaired (CI) states. Importantly, the role of brain white matter microstructural measures in these changes, such as those derived from neurite orientation dispersion and density imaging (NODDI), are poorly understood. We explored roles of cognitive status, brain amyloid pathology, and neurodegeneration on NODDI Free Water (FW), a potential neuroinflammation biomarker. Method Participants enrolled in the Wake Forest Alzheimer’s Disease Research Center (ADRC) Clinical Core cohort (N=74, Table 1) underwent neuropsychological assessment, T1/NODDI MRI, and PiB PET. Participants were adjudicated as cognitively impaired (MCI or AD) or unimpaired using NIA‐AA criteria. T1 MRI were processed (FreeSurfer v5.3) to generate regions of interest (ROIs). An “AD‐signature” cortical thickness value was calculated, and thresholded to classify participants as neurodegeneration‐positive (N+) or ‐negative (N‐). A set of AD‐sensitive cortical ROIs was used to extract mean PET signal, which was thresholded to adjudicate AB positivity (AB‐/AB+). NODDI was processed to yield parameter maps using AMICO; mean isotropic volume fraction (FW) was calculated over a set of white matter tract ROIs. A two‐way ANOVA/ANCOVA (covariates: age, sex, education) assessed effects of neurodegeneration and AB on FW (N+/N‐ x AB+/AB‐), and a two‐way ANOVA/ANCOVA assessed effects of cognitive impairment and AB on FW (CU/CI x AB+/AB‐). Result We first examined effects of neurodegeneration and AB on NODDI FW. We found a significant main effect of neurodegeneration (p=.042), such that N+ had higher FW; this was marginal after adjustment (p=.07). We also observed a significant main effect of AB (p<.001; adjusted p=.012), with AB+ having higher FW. There was no significant interaction. We next explored how cognitive status and AB interacted on FW. We found a significant main effect of cognitive impairment, with CI having higher FW (p=.018; adjusted p=.013). We also found an interaction between diagnosis and AB (p=.037; adjusted p=.044) such that among AB+ individuals, presence of CI related to increased FW (Figure 1). Conclusion NODDI FW increases were significantly affected by the presence of neurodegeneration, AB positivity, and cognitive impairment