Uncertainty Estimation for Quantitative Agarose Gel Electrophoresis of Nucleic Acids.

This paper considers the evaluation of uncertainty of quantitative gel electrophoresis. To date, such uncertainty estimation presented in the literature are based on the multiple measurements performed for assessing the intra- and interlaboratory reproducibility using standard samples. This paper shows how to estimate the uncertainty in cases where we cannot study scattering components of the results. The first point is dedicated to a case where we have standard samples (the direct expressions are shown). The second point considers the situation when standard samples are absent (the algorithm for estimating the lower bound for uncertainty is discussed). The role of the data processing algorithm is demonstrated.

A novel method for multiplex protein biomarker analysis of human serum using quantitative MALDI mass spectrometry.

In this work, we have extended our previously proposed approach for determining protein concentrations in human serum (using MALDI-TOF mass spectrometry) to include simultaneous analysis of several proteins associated with acute inflammation (alpha-2-macroglobulin, fetuin-A, serum amyloid A1). This technique can be used to diagnose systemic inflammation and provides results in 4-5 h. The developed approach was verified using standard immunological methods (ELISA). Samples from 87 individuals, in specific groups, were used for testing and validation: control; inflammatory soft tissue disease accompanied by sepsis; influenza A infection; or COVID-19. The feasibility of differentiating patient groups with the aforementioned conditions was analyzed using a combination of the inflammatory markers described. For fetuin-A and serum amyloid A1, diagnostically significant concentration ranges were established.

Clean and folded: Production of active, high quality recombinant human interferon-λ1.

Type III interferons exhibit antiviral activity against influenza viruses, coronaviruses, rotaviruses, and others. In addition, this type of interferon theoretically has therapeutic advantages, in comparison with type I interferons, due to its ability to activate a narrower group of genes in a relatively small group of target cells. Hence, it can elicit more targeted antiviral or immunomodulatory responses. Obtaining biologically-active interferon lambda (hIFN-λ1) is fraught with difficulties at the stage of expression in soluble form or, in the case of expression in the form of inclusion bodies, at the stage of refolding. In this work, hIFN-λ1 was expressed in the form of inclusion bodies, and a simple, effective refolding method was developed. Efficient and scalable methods for chromatographic purification of recombinant hIFN-λ1 were also developed. High-yield, high-purity product was obtained through optimization of several processes including: recombinant protein expression; metal affinity chromatography; cation exchange chromatography; and an intermediate protein refolding stage. The obtained protein was shown to feature expected specific biological activity in line with published effects: induction of MxA gene expression in A549 cells and antiviral activity against influenza A virus.

Quench me if you can: Alpha-2-macroglobulin trypsin complexes enable serum biomarker analysis by MALDI mass spectrometry.

One of the main functions of alpha-2-macroglobulin (A2M) in human blood serum is the binding of all classes of protease. It is known that trypsin, after such interaction, possesses modified proteolytic activity. Trypsin first hydrolyzes two bonds in A2M's 'bait region', and the peptide 705VGFYESDVMGR715 is released from A2M. In this work, specifics of the A2M-trypsin interaction were used to determine A2M concentration directly in human blood serum using MALDI mass-spectrometry. Following exogenous addition of trypsin to human blood serum in vitro, the concentration of the VGFYESDVMGR peptide was measured, using its isotopically-labeled analogue (18O), and A2M concentration was calculated. The optimized mass spectrometric approach was verified using a standard method for A2M concentration determination (ELISA) and the relevant statistical analysis methods. It was also shown that trypsin's modified proteolytic activity in the presence of serum A2M can be used to analyze other serum proteins, including potential biomarkers of pathological processes. Thus, this work describes a promising approach to serum biomarker analysis that can be technically extended in several useful directions.

Antibody microarray immunoassay for screening and differential diagnosis of upper respiratory tract viral pathogens.

Upper respiratory tract infections are the world's most common infectious disease. The etiologic agents behind upper respiratory tract infections (URTIs) are, in fact, a diverse set of pathogens such as influenza, parainfluenza, adenovirus, rhinovirus, and others. More than 200 pathogens are known to be involved. Differential diagnosis of viral infections is sometimes complicated by their diversity or similarity of clinical presentation. This work is devoted to the development of a method which enables simultaneous detection of six common viral URTI pathogens: IAV; IBV; RSV; hAdV; hPIV2; and hPIV3. Antibody microarray technology is utilized to accomplish the analysis. In preparation for protein microchip creation, we produced, characterized, and selected approximately 50 monoclonal antibodies; for each of the aforementioned pathogens, an optimal monoclonal antibody pair was selected. A protein microchip was created, and its core working conditions were optimized. With a balance between convenience and maximal assay sensitivity in mind, a one-step analysis approach was developed for accomplishing the ELISA-like "sandwich" interaction on the manufactured microchip (antibody microarray). Reference viral strains were used to establish the lower limits of detection (LoD) for the assay. For IAV, the LoD was 0.25 ng/ml total viral protein. For other viruses, the LoD ranged from 1 to 2 ng/ml total protein. These sensitivity limits are slightly better than those of standard ELISA, but inferior to those of PCR. Overall, we believe that the developed microchip is a good alternative to existing methods, allowing relatively quick (overnight), inexpensive, simultaneous screening of several pathogens. The design of the antibody microarray is conducive to further development, and the panel of analyzed pathogens can be expanded to include approximately 50 members.