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Rapid antigen detection tests (Ag-RDT) for SARS-CoV-2 with emergency use authorization generally include a condition of authorization to evaluate the test’s performance in asymptomatic individuals when used serially. We aim to describe a novel study design that was used to generate regulatory-quality data to evaluate the serial use of Ag-RDT in detecting SARS-CoV-2 virus among asymptomatic individuals.
This prospective cohort study used a siteless, digital approach to assess longitudinal performance of Ag-RDT. Individuals over 2 years old from across the USA with no reported COVID-19 symptoms in the 14 days prior to study enrollment were eligible to enroll in this study. Participants throughout the mainland USA were enrolled through a digital platform between October 18, 2021 and February 15, 2022. Participants were asked to test using Ag-RDT and molecular comparators every 48 hours for 15 days. Enrollment demographics, geographic distribution, and SARS-CoV-2 infection rates are reported.
A total of 7361 participants enrolled in the study, and 492 participants tested positive for SARS-CoV-2, including 154 who were asymptomatic and tested negative to start the study. This exceeded the initial enrollment goals of 60 positive participants. We enrolled participants from 44 US states, and geographic distribution of participants shifted in accordance with the changing COVID-19 prevalence nationwide.
The digital site-less approach employed in the “Test Us At Home” study enabled rapid, efficient, and rigorous evaluation of rapid diagnostics for COVID-19 and can be adapted across research disciplines to optimize study enrollment and accessibility.
Gray-level co-occurrence matrix (GLCM) analysis is a contemporary and innovative computational method for the assessment of textural patterns, applicable in almost any area of microscopy. The aim of our research was to perform the GLCM analysis of cell nuclei in Saccharomyces cerevisiae yeast cells after the induction of sublethal cell damage with ethyl alcohol, and to evaluate the performance of various machine learning (ML) models regarding their ability to separate damaged from intact cells. For each cell nucleus, five GLCM parameters were calculated: angular second moment, inverse difference moment, GLCM contrast, GLCM correlation, and textural variance. Based on the obtained GLCM data, we applied three ML approaches: neural network, random trees, and binomial logistic regression. Statistically significant differences in GLCM features were observed between treated and untreated cells. The multilayer perceptron neural network had the highest classification accuracy. The model also showed a relatively high level of sensitivity and specificity, as well as an excellent discriminatory power in the separation of treated from untreated cells. To the best of our knowledge, this is the first study to demonstrate that it is possible to create a relatively sensitive GLCM-based ML model for the detection of alcohol-induced damage in Saccharomyces cerevisiae cell nuclei.
Dual inhibition (2i) of Ras–MEK–ERK and GSK3β pathways enables the derivation of embryo stem cells (ESCs) from refractory mouse strains and, for permissive strains, allows ESC derivation with no external protein factor stimuli involvement. In addition, blocking of ERK signalling in 8-cell-stage mouse embryos leads to ablation of GATA4/6 expression in hypoblasts, suggesting fibroblast growth factor (FGF) dependence of hypoblast formation in the mouse. In human, bovine or porcine embryos, the hypoblast remains unaffected or displays slight-to-moderate reduction in cell number. In this study, we demonstrated that segregation of the hypoblast and the epiblast in rabbit embryos is FGF independent and 2i treatment elicits only a limited reinforcement in favour of OCT4-positive epiblast populations against the GATA4-/6-positive hypoblast population. It has been previously shown that TGFβ/Activin A inhibition overcomes the pervasive differentiation and inhomogeneity of rat iPSCs, rat ESCs and human iPSCs while prompting them to acquire naïve properties. However, TGFβ/Activin A inhibition, alone or together with Rho-associated, coiled-coil containing protein kinase (ROCK) inhibition, was not compatible with the viability of rabbit embryos according to the ultrastructural analysis of preimplantation rabbit embryos by electron microscopy. In rabbit models ovulation upon mating allows the precise timing of progression of the pregnancy. It produces several embryos of the desired stage in one pregnancy and a relatively short gestation period, making the rabbit embryo a suitable model to discover the cellular functions and mechanisms of maintenance of pluripotency in embryonic cells and the embryo-derived stem cells of other mammals.
Determining infectious cross-transmission events in healthcare settings involves manual surveillance of case clusters by infection control personnel, followed by strain typing of clinical/environmental isolates suspected in said clusters. Recent advances in genomic sequencing and cloud computing now allow for the rapid molecular typing of infecting isolates.
To facilitate rapid recognition of transmission clusters, we aimed to assess infection control surveillance using whole-genome sequencing (WGS) of microbial pathogens to identify cross-transmission events for epidemiologic review.
Clinical isolates of Staphylococcus aureus, Enterococcus faecium, Pseudomonas aeruginosa, and Klebsiella pneumoniae were obtained prospectively at an academic medical center, from September 1, 2016, to September 30, 2017. Isolate genomes were sequenced, followed by single-nucleotide variant analysis; a cloud-computing platform was used for whole-genome sequence analysis and cluster identification.
Most strains of the 4 studied pathogens were unrelated, and 34 potential transmission clusters were present. The characteristics of the potential clusters were complex and likely not identifiable by traditional surveillance alone. Notably, only 1 cluster had been suspected by routine manual surveillance.
Our work supports the assertion that integration of genomic and clinical epidemiologic data can augment infection control surveillance for both the identification of cross-transmission events and the inclusion of missed and exclusion of misidentified outbreaks (ie, false alarms). The integration of clinical data is essential to prioritize suspect clusters for investigation, and for existing infections, a timely review of both the clinical and WGS results can hold promise to reduce HAIs. A richer understanding of cross-transmission events within healthcare settings will require the expansion of current surveillance approaches.
Red fox (Vulpes vulpes) is the most abundant wild canid species in Austria, and it is a well-known carrier of many pathogens of medical and veterinary concern. The main aim of the present study was to investigate the occurrence and diversity of protozoan, bacterial and filarial parasites transmitted by blood-feeding arthropods in a red fox population in western Austria. Blood (n = 351) and spleen (n = 506) samples from foxes were examined by PCR and sequencing and the following pathogens were identified: Babesia canis, Babesia cf. microti (syn. Theileria annae), Hepatozoon canis, Anaplasma phagocytophilum, Candidatus Neoehrlichia sp. and Bartonella rochalimae. Blood was shown to be more suitable for detection of Babesia cf. microti, whilst the spleen tissue was better for detection of H. canis than blood. Moreover, extremely low genetic variability of H. canis and its relatively low prevalence rate observed in this study may suggest that the parasite has only recently been introduced in the sampled area. Furthermore, the data presented here demonstrates, for the first time, the possible vertical transmission of H. canis from an infected vixen to the offspring, and this could explain the very high prevalence in areas considered free of its main tick vector(s).
This investigation tested the hypothesis that the effects of nitric oxide synthase on myocardial capillary perfusion were reduced during myocardial stunning. Anaesthetized open-chest rabbits were assigned to either a control group or a group treated with a nitric oxide synthase inhibitor. To induce myocardial stunning, a coronary artery was occluded (for 15 min) and then reperfused (for 15 min) twice. During reperfusion, rabbits were given either saline or NG-nitro-L-arginine methyl ester (L-NAME, 30 mg kg-1) followed by I.V. injection of 150 mg kg-1 fluorescein isothiocyanate (FITC)-labelled dextran (molecular weight, 150 000) for 14 s. Fluorescence microscopy was used to identify the perfused vessels and an alkaline phosphatase stain was used to locate the total microvasculature. The 'closest-individual' method was used to estimate the geometric distribution of capillaries. No significant differences were observed in the total volume fraction (mm3 of capillaries per mm3 of tissue) between the control and stunned regions in either the saline- (0.045 ± 0.008 and 0.042 ± 0.009, respectively) or the L-NAME-treated hearts (0.060 ± 0.010 and 0.049 ± 0.005, respectively). There were no significant differences in the percentage volume fraction of perfused capillaries between the control and the stunned regions (49 ± 4 % and 54 ± 4 %, respectively) in saline-treated hearts. In hearts treated with L-NAME, the percentage of perfused capillaries was significantly reduced. The reduction was significantly greater in the control region (~27 %) than the stunned region (~17 %). Closest-individual analysis of the perfused capillary distribution in both groups demonstrated a similar unchanged distribution. Thus, nitric oxide synthase is an important regulator of basal coronary capillary perfusion, and its effects are significantly reduced by myocardial stunning. Experimental Physiology (2002) 87.3, 335-342.
Between 1987 and 1990 a large series of at-risk individuals has been referred to our Huntington's disease (HD) presymptomatic testing programme. A detailed protocol for assessment and counselling has been followed. Out of 238 serious inquiries, 36% were potentially suitable for the testing programme, but 19% chose not to continue. Reasons for exclusion included the presence of clinical features of HD and being under the age of 18 years. Out of 40 final results given to 38 individuals, 23 indicated a lowered risk, 11 an increased risk, while five results were uninformative, two of these becoming informative on repeat testing. This series contained more women than men, and was disproportionately from the higher socio-economic groups. Motives for requesting a test principally related to child-bearing, informing existing children, and planning for the future. No significant psychiatric symptoms have been reported in the short term, but difficult counselling problems were presented by the high proportion of applicants who already showed clinical signs of HD. It is concluded that a detailed counselling protocol is essential in testing for HD, as many applicants are ill-prepared; this will assume even greater importance when the HD gene is identified and a test for specific mutations is available. The experience of presymptomatic testing for HD provides important general lessons which are likely to be applicable to other inherited neurological and psychiatric disorders.
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