High-throughput quantitation of SARS-CoV-2 antibodies in a single-dilution homogeneous assay.

SARS-CoV-2 emerged in late 2019 and has since spread around the world, causing a pandemic of the respiratory disease COVID-19. Detecting antibodies against the virus is an essential tool for tracking infections and developing vaccines. Such tests, primarily utilizing the enzyme-linked immunosorbent assay (ELISA) principle, can be either qualitative (reporting positive/negative results) or quantitative (reporting a value representing the quantity of specific antibodies). Quantitation is vital for determining stability or decline of antibody titers in convalescence, efficacy of different vaccination regimens, and detection of asymptomatic infections. Quantitation typically requires two-step ELISA testing, in which samples are first screened in a qualitative assay and positive samples are subsequently analyzed as a dilution series. To overcome the throughput limitations of this approach, we developed a simpler and faster system that is highly automatable and achieves quantitation in a single-dilution screening format with sensitivity and specificity comparable to those of ELISA.

Assessment of Inhibitors of Pathogenic Crimean-Congo Hemorrhagic Fever Virus Strains Using Virus-Like Particles.

Crimean-Congo hemorrhagic fever (CCHF) is an often lethal, acute inflammatory illness that affects a large geographic area. The disease is caused by infection with CCHF virus (CCHFV), a nairovirus from the Bunyaviridae family. Basic research on CCHFV has been severely hampered by biosafety requirements and lack of available strains and molecular tools. We report the development of a CCHF transcription- and entry-competent virus-like particle (tecVLP) system that can be used to study cell entry and viral transcription/replication over a broad dynamic range (~4 orders of magnitude). The tecVLPs are morphologically similar to authentic CCHFV. Incubation of immortalized and primary human cells with tecVLPs results in a strong reporter signal that is sensitive to treatment with neutralizing monoclonal antibodies and by small molecule inhibitors of CCHFV. We used glycoproteins and minigenomes from divergent CCHFV strains to generate tecVLPs, and in doing so, we identified a monoclonal antibody that can prevent cell entry of tecVLPs containing glycoproteins from 3 pathogenic CCHFV strains. In addition, our data suggest that different glycoprotein moieties confer different cellular entry efficiencies, and that glycoproteins from the commonly used strain IbAr10200 have up to 100-fold lower ability to enter primary human cells compared to glycoproteins from pathogenic CCHFV strains.

A simple fall in the elderly: not so simple.

BACKGROUND: The goal of this study was to evaluate the burden of falls in the elderly in a Canadian tertiary trauma center. METHODS: Patients admitted to Charles-LeMoyne Hospital with a low velocity fall (LVF) from April 1, 1993 to March 31, 2000 were individually reviewed. Elderly was defined as age 65 years and older. A region was considered to be injured if Abbreviated Injury Scale was greater than or equal to 2. RESULTS: There were 2,333 patients with LVF, 41.4% of all blunt trauma admissions. Median Injury Severity Score was 9 for elderly compared with 5 for young (p < 0.001). Injuries were significantly more frequent to head, face, thorax, and lower limbs in the elderly. Mortality (13.4% versus 0.9%; p < 0.001), length of stay (median = 15 versus 3 days; p < 0.001) and long-term care facility reference (19.3% versus 1.1%, p < 0.001) were significantly higher in the elderly. CONCLUSIONS: LVF is a frequent cause of admission for trauma in the elderly. Despite the apparent benign nature of the mechanism, LVF is associated with more severe injuries and worse outcome.

Spill your guts! Perceptions of Trauma Association of Canada member surgeons regarding the open abdomen and the abdominal compartment syndrome.

BACKGROUND: To survey surgeon opinion regarding the management of the open abdomen (OA) and abdominal compartment syndrome (ACS) to assess current practice and direct future prospective clinical studies. METHODS: Opinions of self-designated trauma, general, pediatric, and vascular surgeons belonging to the Trauma Association of Canada (TAC), were surveyed through a mixed-mode (mail and Web based) questionnaire. RESULTS: Among 102 eligible candidates, 86 (84%) responded; 83% did regular trauma call, 45% regular critical care call being a separate call 79% of the time; 79% worked in centers serving >500,000 people; the median year of practice entry was 1997. There was no standard definition of what constituted an "open abdomen", preferred time for re-operation, or preferred method for alternate fascial closure, although 90% reported having not closing the fascia after a trauma laparotomy. Being "physically unable" was reported as an indication twice as often as objective measures of airway or bladder pressures. The decision to proceed with OA was reported as rarely or never being made preoperatively by 78% of respondents. None reported an institutional policy regarding OA. Eighty-four percent reported (re)opening an abdomen for primary ACS, 46% for secondary ACS, 28% for tertiary ACS. Self-assessed familiarity for the ACS was 6/7 on a Likert scale. Physical examination was reported as a diagnostic criterion for ACS by 66%, and used to screen by 21% of respondents. CONCLUSIONS: There is no consensus regarding definition, functional indications, or management of an open abdomen in the perceptions of Canadian trauma providers despite a high self reported level of familiarity with the abdominal compartment syndrome. This is an area of practice with potential and requirements for further multi-center study.

Paying the price of excluding patients from a trauma registry.

BACKGROUND: The goal of this study was to evaluate the impact of different trauma registry exclusion criteria on the assessment of trauma populations and outcome. METHODS: All patients admitted to a Canadian regional trauma center from April 1, 1993 to March 31, 2002 with a diagnosis of trauma (ICD-9 codes 800 to 959) were reviewed. TOTAL included everyone. REGISTRY included only patients meeting any of four criteria: death during hospital stay, transfer received from another hospital, admission to the intensive care unit, or hospital stay of 3 days or more. NOHIP excluded patients with isolated hip fracture. REG/NOHIP combined both. ISS12 and ISS15 excluded patients with ISS <12 and 15, respectively. RESULTS: There were 6,839 trauma patients. The percentage of excluded patients by group was: REGISTRY, 21.2%; NOHIP, 14.7%; REG/NOHIP, 34.9%; ISS12, 75%; and ISS15, 80.3%. Median length of stay was 7 days. Exclusions represented a total number of hospitalization days varying from 1.9% to 65.5% of TOTAL. Mortality was 6.9% for TOTAL, 8.6% for REGISTRY (p < 0.001), 5.7% for NOHIP (p = 0.009), 7.5% for REG/NOHIP (p=NS), 16.1% for ISS12 (p < 0.001), and 20.4% for ISS15 (p < 0.001). In groups with exclusions, transfer to long-term care varied from 0.14% to 23.5% in the excluded patients. For rehabilitation, these percentages varied from 0.14% to 17.6%. CONCLUSIONS: Registry exclusion criteria significantly alter the apparent severity of injury and resource utilization. The use of divergent exclusion criteria in the analysis of trauma registry data may be misleading.

Statistical validation of the Revised Trauma Score.

BACKGROUND: To validate the accuracy of the Revised Trauma Score (RTS) and its components for predicting in-hospital mortality. METHODS: Analyses were based on 22,388 patients from the trauma registries of three urban Level I trauma centers in the province of Quebec, Canada. The accuracy of RTS coded variables for the Glasgow Coma Score (GCSc), Systolic Blood Pressure (SBPc), and Respiratory Rate (RRc) for predicting mortality was evaluated in logistic regression models with measures of discrimination and model fit and compared with Fractional Polynomial (FP) transformations of each component. RESULTS: RTS coded variables were associated with sparse data distributions and did not accurately represent the relation of GCS, SBP, and RR to mortality. FP models were always associated with significantly better discrimination (all p < 0.00001) and model fit. Survival probability estimates generated by the model with FP transformations were significantly different to those generated by the model with RTS-coded variables. CONCLUSIONS: The RTS in its present form does not accurately describe the relation of GCS, SBP, and RR to mortality. FP transformation would improve the accuracy of predicted survival probabilities used for performance evaluation and may improve control of confounding caused by of physiologic severity case mix in trauma research.

Multiple imputation of the Glasgow Coma Score.

BACKGROUND: To investigate whether multiple imputation (MI) of missing Glasgow Coma Scale (GCS) values generates more accurate GCS frequency distributions and less biased parameter estimates in logistic regression models predicting mortality than the standard procedure of excluding observations with missing GCS values. METHODS: The study population consisted of 5,065 patients with complete GCS information from the trauma registry of a Level 1 trauma center. Missing GCS values were imposed on the data set, and the performance of MI (extrapolating missing GCS from a data prediction model) and of deleting all data observations with missing GCS (list-wise deletion) were evaluated. GCS and Trauma and Injury Severity Score (TRISS) frequency distributions and parameter estimates were compared with true values from the original data set. RESULTS: GCS and TRISS frequency values generated by MI were much more accurate than those generated by list-wise deletion. GCS and TRISS parameter estimates generated by MI all had acceptable bias and coverage rates when compared with true values. List-wise deletion provided biased parameter estimates for the GCS, the Revised Trauma Score, and the Injury Severity Score. CONCLUSION: MI is a valid solution to the problem of missing GCS data in trauma research. It allows the conservation of precious data observations and leads to unbiased estimates in consequent analyses. Analyses, which exclude observations with missing GCS data, provide biased results.