Capillary blood stability and analytical accuracy of 12 analytes stored in Microtainers®.

Objectives: The aim of this study was to determine feasibility of collecting capillary blood by traditional fingerstick and next day analysis after transport in Microtainers® at ambient temperature with no plasma separation. This study is pursuing an acceptable alternative to venipuncture for measuring 12 analytes important for health risk assessment. Design: and Methods: Performance standards of a 12-assay chemistry panel were assessed using a set of paralleled serum and capillary microsamples. The panel included Hemoglobin A1c (HbA1c), Total Cholesterol, Triglycerides, HDL-C, Creatinine, Urea Nitrogen (BUN), Uric Acid, alkaline phosphatase (ALP), ALT (GPT), AST (GOT), gamma-glutamyltransferase (GGT), and total protein. Correlation studies were performed using 31 simultaneous venous and capillary blood collections. Analytical bias, correlation, and medical decision points were calculated to determine equivalency of sample type and the impact of transport conditions. Clinical sensitivity, specificity, and predictive values were evaluated at calculated medical decision points for their usability in health screening initiatives. Results: Laboratory test results using capillary blood samples stored in Microtainers® under conditions of delayed centrifugation, and mail transport at ambient temperature, showed an acceptable agreement with results obtained using their paired serum samples analyzed using standard methods, except AST. Conclusions: Capillary blood samples can be self-collected at remote locations using Microtainers® and transported at ambient temperature for 24 h for successful performance of several medical tests important in large-scale health screenings programs.

Analysis of SARS-CoV-2 antibodies from dried blood spot samples with the Roche Elecsys Immunochemistry method.

OBJECTIVES: The aim of this study was to evaluate the application of the Roche Elecsys anti-SARS-CoV-2 assay to capillary dried blood samples for high throughput analyses on Roche COBAS 6000 systems. DESIGN AND METHODS: The performance of the of the Elecsys anti-SARS-CoV-2 assay was assessed using three sets of dried blood spot samples. Method correlation was performed using spiked blood samples. Sensitivity and specificity were calculated using paired donor samples. An additional cohort of 50 individuals, including COVID-19 convalescent cases, was used for the evaluation of at-home collection for mail transport, and stability studies. RESULTS: The Elecsys anti-SARS-CoV-2 assay using dried blood spot samples showed an excellent agreement of 98.9% with results obtained using their paired serum samples, and 86.7% accuracy with dried blood spots collected after 9 days from diagnostic (PCR) tests. CONCLUSIONS: Capillary dried blood spot samples can be confidently used on Roche COBAS automated analyzers to monitor the epidemiology of COVID-19, and are suitable for use in large-scale screening programs.

Gene regulatory networks controlling vertebrate retinal regeneration.

Injury induces retinal Müller glia of certain cold-blooded vertebrates, but not those of mammals, to regenerate neurons. To identify gene regulatory networks that reprogram Müller glia into progenitor cells, we profiled changes in gene expression and chromatin accessibility in Müller glia from zebrafish, chick, and mice in response to different stimuli. We identified evolutionarily conserved and species-specific gene networks controlling glial quiescence, reactivity, and neurogenesis. In zebrafish and chick, the transition from quiescence to reactivity is essential for retinal regeneration, whereas in mice, a dedicated network suppresses neurogenic competence and restores quiescence. Disruption of nuclear factor I transcription factors, which maintain and restore quiescence, induces Müller glia to proliferate and generate neurons in adult mice after injury. These findings may aid in designing therapies to restore retinal neurons lost to degenerative diseases.

Analysis of MinD mutations reveals residues required for MinE stimulation of the MinD ATPase and residues required for MinC interaction.

The MinD ATPase is critical to the oscillation of the Min proteins, which limits formation of the Z ring to midcell. In the presence of ATP, MinD binds to the membrane and recruits MinC, forming a complex that can destabilize the cytokinetic Z ring. MinE, which is also recruited to the membrane by MinD, displaces MinC and stimulates the MinD ATPase, resulting in the oscillation of the Min proteins. In this study we have investigated the role of lysine 11, present in the deviant Walker A motif of MinD, and the three residues in helix 7 (E146, S148, and D152) that interact electrostatically with lysine 11. Lysine 11 is required for interaction of MinD with the membrane, MinC, MinE, and itself. In contrast, the three residues in helix 7 that interact with lysine 11 are not required for binding to the membrane or activation of MinC. They are also not required for MinE binding; however, they are required for MinE to stimulate the MinD ATPase. Interestingly, the D152A mutant self-interacts, binds to the membrane, and recruits MinC and MinE in the presence of ADP as well as ATP. This mutant provides evidence that dimerization of MinD is sufficient for MinD to bind the membrane and recruit its partners.

Recruitment of MinC, an inhibitor of Z-ring formation, to the membrane in Escherichia coli: role of MinD and MinE.

In Escherichia coli, the min system prevents division away from midcell through topological regulation of MinC, an inhibitor of Z-ring formation. The topological regulation involves oscillation of MinC between the poles of the cell under the direction of the MinDE oscillator. Since the mechanism of MinC involvement in the oscillation is unknown, we investigated the interaction of MinC with the other Min proteins. We observed that MinD dimerized in the presence of ATP and interacted with MinC. In the presence of a phospholipid bilayer, MinD bound to the bilayer and recruited MinC in an ATP-dependent manner. Addition of MinE to the MinCD-bilayer complex resulted in release of both MinC and MinD. The release of MinC did not require ATP hydrolysis, indicating that MinE could displace MinC from the MinD-bilayer complex. In contrast, MinC was unable to displace MinE bound to the MinD-bilayer complex. These results suggest that MinE induces a conformational change in MinD bound to the bilayer that results in the release of MinC. Also, it is argued that binding of MinD to the membrane activates MinC.

Bioadhesives: a biotechnological opportunity

Marine mussels secrete the byssus in order to attach to solid surfaces and to servive under the turbulent effects of waves. The adhesive responsable for this atachment is the polyphenolic protein secreted by the phenol gland in the foot of the animal To purify this adhesive protein form the chilean mussel Mylilus chilensis, a modification of previous procedures has been developed. Accordingly, the protein is differentially precipitated with acetone in the presence of 0.25 N HCl. The purified protein is rich in the amino acids lysine, 3,4-dihydroxyphenylalanine, serine, threonine, proline and hydrozyproline. The protein exhibited strong adhesion to glass and other solid supports. Moreover, its has been found that the adhesive protein can mediate the immobilization of ß-galactosidase to glass. About 75% of the enzyme activity was immobilized under the experimental conditions described. This is the first study reporting the use of the polyphenolic protein to immobilize enzymes