Multicenter Evaluation of the Clinical Performance and the Neutralizing Antibody Activity Prediction Properties of 10 High-Throughput Serological Assays Used in Clinical Laboratories.

As the coronavirus disease 2019 (COVID-19) pandemic second wave is emerging, it is of the upmost importance to screen the population immunity in order to keep track of infected individuals. Consequently, immunoassays for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with high specificity and positive predictive values are needed to obtain an accurate epidemiological picture. As more data accumulate about the immune responses and the kinetics of neutralizing-antibody (nAb) production in SARS-CoV-2-infected individuals, new applications are forecast for serological assays such as nAb activity prediction in convalescent-phase plasma from recovered patients. This multicenter study, involving six hospital centers, determined the baseline clinical performances, reproducibility, and nAb level correlations of 10 commercially available immunoassays. In addition, three lateral-flow chromatography assays were evaluated, as these devices can be used in logistically challenged areas. All assays were evaluated using the same patient panels in duplicate, thus enabling accurate comparison of the tests. Seven immunoassays examined in this study were shown to have excellent specificity (98 to 100%) and good to excellent positive predictive values (82 to 100%) when used in a low (5%)-seroprevalence setting. We observed sensitivities as low as 74% and as high as 95% at ≥15 days after symptom onset. The determination of optimized cutoff values through receiver operating characteristic (ROC) curve analyses had a significant impact on the diagnostic resolution of several enzyme immunoassays by increasing the sensitivity significantly without a large trade-off in specificity. We found that spike-based immunoassays seem to be better correlates of nAb activity. Finally, the results reported here will add to the general knowledge of the interlaboratory reproducibility of clinical performance parameters of immunoassays and provide new evidence about nAb activity prediction.

Comparative proteome and lipid profiles of bovine epididymosomes collected in the intraluminal compartment of the caput and cauda epididymidis.

During the epididymal maturation, spermatozoa interact with different populations of epididymosomes and sequentially acquire some epididymosome-associated proteins critical to sperm functions. Although very few proteins associated with epididymosomes have been identified, the physiological importance of these vesicles in the sperm maturation remains unclear. To document these relevant issues, lipid and protein analysis of epididymosomes from caput and cauda epididymal fluids was determined. Lipid analysis revealed a particular composition of specific phospholipids in these vesicles; the levels of phosphatidyl-ethanolamine, phosphatidyl-inositol and phosphatidyl-choline being higher in caput epididymosomes. From the 555 and 438 proteins identified in caput- and cauda-derived epididymosomes, respectively, 231 proteins were identified in both types of epididymosome. Proteins exclusively identified in caput and cauda epididymosomes are mainly enzymes and transporter molecules. The presence of several glycan-modifying enzymes is the hallmark of the caput epididymosomes proteome. Among the common proteins in both types of epididymosome, a subset of Rab and SNARE proteins implicated in vesicle trafficking and membrane fusion were identified. Together, these data suggest that epididymosome-associated proteins are involved in various molecular functions suggesting that during the epididymal transit, spermatozoa interact with different populations of epididymosomes, which could modify the male gamete in a sequential manner.

Multicenter evaluation of the Glucometer Elite XL meter, an instrument specifically designed for use with neonates.

OBJECTIVE: To evaluate the clinical performance of the Glucometer Elite XL Diabetes Care System in neonatal settings using a multicenter study RESEARCH DESIGN AND METHODS: A total of 388 blood specimens from 333 neonates were included in the study. A capillary or arterial sample was analyzed for determination of glucose with the Glucometer Elite XL system by an attending trained nurse. Through the same sampling site, a specimen was collected and sent to the laboratory for measurement of plasma glucose, bilirubin, and hematocrit. RESULTS: The regression analysis between the results of the Glucometer Elite XL system and comparative methods resulted in the following: Glucometer Elite XL meter = 1.01 x laboratory method + 0.02 mmol/l (n = 388). For the 1.1-4.0 mmol/l plasma glucose range, the regression was Glucometer Elite XL meter = 1.07 x laboratory method + 0.12 mmol/l (n = 150). A difference plot indicated a mean bias of 0.04 mmol/l (95% CI -0.01 to 0.10). No relationship was found between meter glucose biases and hematocrit levels (r = 0.10, P = 0.14). Although a statistically significant correlation existed between bilirubin levels and the glucose meter biases (r = 0.14, P = 0.005), the predicted mean biases were of little clinical significance. CONCLUSIONS: The Glucometer Elite XL system showed a good performance when used in neonatal settings.