h-hydrogen

High sensitivity of analysis is constantly in demand in biomedical research and clinical diagnosis. In recent years aptamer-based analytical methods have been developed for protein detection. We developed a cascade signal amplification strategy based on molecular switches and aptamers to improve protein detection.

Our cascade signal amplification strategy based on molecular switches and aptamers consisted of 2 steps, including the recognition and the triggering of a polymerase reaction. The procedure was designed to simplify the analysis by detecting trace amounts of target isothermally, in real time, and in a homogeneous solution. We applied this method to measure thrombin in human serum samples.

This cascade signal amplification strategy exhibited a linear response in thrombin concentration from 0.3 to 10 nmol/L, with a detection limit of 1.7 x 10^–10 mol/L within 60 min. Results of the analysis of thrombin in human serum diluted 1:1 appeared to be linear, as was observed in buffer, in the tested concentration range of 0.3–10 nmol/L.

The aptameric sensor provides promising potential for detecting and screening trace concentrations of biomarkers in complex matrices for clinical applications.

Biomarkers and metabolites related to B vitamin function and one-carbon metabolism have been studied as predictors of chronic diseases in studies based on samples stored in biobanks. For most biomarkers, stability data are lacking or fragmentary.

Degradation and accumulation kinetics of 32 biomarkers were determined at 23 °C in serum and plasma (EDTA, heparin, and citrate) collected from 16 individuals and stored for up to 8 days. In frozen serum (–25 °C), stability was studied cross-sectionally in 650 archival samples stored for up to 29 years. Concentration vs time curves were fitted to monoexponential, biexponential, linear, and nonlinear models.

For many biomarkers, stability was highest in EDTA plasma. Storage effects were similar at room temperature and at –25 °C; notable exceptions were methionine, which could be recovered as methionine sulfoxide, and cystathionine, which decreased in frozen samples. Cobalamin, betaine, dimethylglycine, sarcosine, total homocysteine, total cysteine, tryptophan, asymetric and symmetric dimethyl argenine, creatinine, and methylmalonic acid were essentially stable under all conditions. Most B vitamins (folate and vitamins B2 and B6) were unstable; choline increased markedly, and some amino acids also increased, particularly in serum. The kynurenines showed variable stability. For many biomarkers, degradation (folate and flavin mononucleotide) or accumulation (pyridoxal, riboflavin, choline, amino acids) kinetics at room temperature were non–first order.

Data on stability and deterioration kinetics for individual biomarkers are required to optimize procedures for handling serum and plasma, and for addressing preanalytical bias in epidemiological and clinical studies.

Pneumatic tube systems (PTSs) for the transport of blood samples are regaining popularity in medical centers after earlier reports that their use could introduce preanalytical distortions such as hemolysis and changes in blood gases.

We drew duplicate blood samples from 30 volunteers. One sample was hand transported, and the other sample was transported through a PTS together with a mini–data logger that provided continuous measurements of temperature, humidity, pressure, and acceleration. After transport the samples were analyzed at the same time. We looked for possible relationships of the transport method and the parameters measured by the data loggers with differences in hematological parameters, standard clinical chemistry analyses, blood coagulation, erythrocyte sedimentation rate, and blood gas analysis.

There were no significant differences in temperature, humidity, and pressure between the methods of transport, but we observed significant differences in 3-axis accelerations. The combined effect of these forces could be described by the right-tailed area under the vector sum acceleration distribution. Our data show that this area correlated with PTS speed and that PTS speed and the area under the curve exhibited a direct relation to the degree of hemolysis.

Assessment of 3-axis acceleration by use of data loggers can be used to identify preanalytical deviations that result from the transportation of blood samples in PTSs. Our approach could be used for the evaluation and regular control of PTSs without the need for repeated blood drawing and laboratory analyses.

Interest in lysosomal storage disorders, a collection of more than 40 inherited metabolic disorders, has increased because of new therapy options such as enzyme replacement, stem cell transplantation, and substrate reduction therapy. We developed a high-throughput protocol that simplifies analytical challenges such as complex sample preparation and potential interference from excess residual substrate associated with previously reported assays.

After overnight incubation (16–20 h) of dried blood spots with a cassette of substrates and deuterated internal standards, we used a TLX-2 system to quantify 6 lysosomal enzyme activities for Fabry, Gaucher, Niemann-Pick A/B, Pompe, Krabbe, and mucopolysaccharidosis I disease. This multiplexed, multidimensional ultra-HPLC–tandem mass spectrometry assay included Cyclone P Turbo Flow and Hypersil Gold C8 columns. The method did not require offline sample preparation such as liquid–liquid and solid-phase extraction, or hazardous reagents such as ethyl acetate.

Obviating the offline sample preparation steps led to substantial savings in analytical time (approximately 70%) and reagent costs (approximately 50%). In a pilot study, lysosomal enzyme activities of 8586 newborns were measured, including 51 positive controls, and the results demonstrated 100% diagnostic sensitivity and high specificity. The results for Krabbe disease were validated with parallel measurements by the New York State Screening Laboratory.

Turboflow online sample cleanup and the use of an additional analytical column enabled the implementation of lysosomal storage disorder testing in a nationwide screening program while keeping the total analysis time to <2 min per sample.

Current standard operating procedures for salivary transcriptomic analysis require low temperatures and lengthy mRNA isolation, which substantially hamper its use in the clinic. We developed a streamlined, ambient-temperature processing, stabilization, and storage protocol for clinical analysis of salivary RNA.

The direct saliva transcriptome analysis (DSTA) used cell-free saliva supernatant instead of isolated mRNA for saliva transcriptomic detection, and all procedures, including processing, stabilization, and storage of saliva samples, were performed at ambient temperature without a stabilizing reagent. We evaluated this streamlined protocol by comparing the mRNA expression levels of 3 saliva internal reference genes [glyceraldehyde-3-phosphate dehydrogenase (GAPDH); actin, beta (ACTB); and ribosomal protein S9 (RPS9)] to levels measured with standard procedures, and detecting the variation of their expression levels under long-term ambient temperature storage. The clinical utility of DSTA was assessed by use of 7 oral cancer salivary mRNA biomarkers in a clinical study.

Each saliva internal reference gene mRNA showed similar expression levels when assayed by the DSTA or standard procedures, and remained stable under ambient temperature storage for at least 10 weeks without significant degradation (P = 0.918, 0.288, and 0.242 for GAPDH, ACTB, and RPS9, respectively). Compared with standard procedures, the performance characteristics of oral cancer salivary transcriptomic markers were retained as assayed by DSTA after 10 weeks of storage at ambient temperature. These results indicate that the DSTA is a suitable alternative method for saliva transcriptomic analysis and is feasible for use in clinical cancer research applications.

The streamlined DSTA protocol can impact the saliva-handling method and improve the standard operating procedures for clinical saliva transcriptomic diagnostics.

Background: Prospect biomarkers discovered with high-throughput proteomic techniques (along with multitudinous biomarkers reported in the literature) have to be rigorously validated. The contemporaneous quantitative assessment of multiple unrealized biomarkers across strapping cohorts presents a dominating summons to the competitors. Multiplex immunoassays reflect a favourable solution, with the unrealized to take measures quantitative facts via uniform analyses. These assays also insist for the most part less test and reagents than the unwritten ELISA (which is besides predetermined by its power to as solitary a set aside antigen). We comprise cautious the reproducibility, reliability, robustness, accuracy, and throughput of commercially elbow multiplex immunoassays to ascertain their suitability for serum biomarker assay and validation.

Methods: Assay platforms MULTI-ARRAY (Meso Calibration Discovery), Bio-Plex (Bio-Rad Laboratories), A² (Beckman Coulter), FAST Quant (Whatman Schleicher & Schuell BioScience), and FlowCytomix (Bender MedSystems) were selected as commissioner examples of technologies currently hardened for high-throughput immunoanalysis. All assays were performed according to protocols specified by the manufacturers and with the reagents (diluents, calibrators, blocking reagents, and detecting-antibody mixtures) included with their kits.

Results: The quantifiable wait unwavering for each assay and antigen was based on faithfulness (CV < 25%) and part retrieval (measured concentration within 20% of the realistic concentration). The MULTI-ARRAY and Bio-Plex assays had the excellent exhibition with the lowest limits of detection, and the MULTI-ARRAY technique had the most linear signal crop at an end the widest concentration limit (10⁵ to 10⁶). Cytokine concentrations in unspiked and cytokine-spiked serum samples from in the pink individuals were patronize investigated with the MULTI-ARRAY and Bio-Plex assays.

Conclusions: The MULTI-ARRAY and Bio-Plex multiplex immunoassay systems are the most correct for biomarker review or quantification.

Background: Oceans spectrometry (MS) is a fitting technology for microorganism pinpointing and characterization.

Content: This review summarizes the MS-based methods currently second-hand for the analyses of pathogens. Direct enquiry of lot pathogenic microbial cells using MS without test fractionation reveals definitive biomarkers for taxonomy and provides impetuous and high-throughput capabilities. MS coupled with individual chromatography- and affinity-based techniques simplifies the complicatedness of the signals of the microbial biomarkers and provides more for detail results. Affinity-based methods, including those employing nanotechnology, can be used to intensify traces of objective microorganisms from cross-section solutions and, thereby, enhance detection limits. Approaches combining amplification of nucleic acid targets from pathogens with MS-based detection are alternatives to biomarker analyses. Numberless observations enquiry methods, including multivariate inquiry and bioinformatics approaches, take been developed for microbial cataloguing. The critique concludes with some course clinical applications of MS in the indication and typing of catching microorganisms, as well as some perspectives.

Summary: Advances in instrumentation (separation and lot analysis), ionization techniques, and biological methodologies will all enhance the capabilities of MS for the analysis of pathogens.

Background: Accrediting organizations make laboratories to substantiate analytic exhibition criteria that guarantee their tests anticipate results of the important importance required for sufferer heedfulness. However, the procedures for instituting exhibit criteria that are without delay linked to the needs of medical exercise are not well established, and for that reason surrogate strategies in many cases are tolerant of to create and device surrogate show standards.

Content: We reviewed 6 approaches for establishing outcome-related analytic effectuation goals: (a) limits defined by regulations and apparent assessment programs, (b) limits based on biologic variation, (c) limits based on surveys of clinicians reciprocity their needs, (d) limits based on effects on guideline driven medical decisions, (e) limits based on examination of patterns for ordering follow-up clinical tests, and (f) limits based on formal medical conclusiveness models. Playing criteria were tabulated for 12 common chemistry analytes and 4 programmed hematology tests.

Conclusions: There is no consensus currently reciprocity the preferred methods for establishing medically certain analytic conduct limits. The heterogeneous methods reviewed make considerably contrary execution limits. The analytic playing limits claimed by a laboratory should be in touch to those limits that can be reliably maintained based on validated QC monitoring systems. These limits mainly are larger than the observed CVs and proclivity parameters calm for assay validation. There is a important constraint for increased communication total laboratorians and clinicians on this topic, especially when the analytic deportment limits that can be resolutely maintained by a laboratory are inconsistent with the expectations of fitness caution providers.

Background: Galactosemia is one of the most arrogant inherited disorders detected by newborn screening tests. Psych jargon exceptional results in screening tests should be confirmed by enzyme energy assays, but existing methods are on many occasions and labor concentrated. We developed a blockbuster multiplex enzyme assay for galactosemia using ultraperformance brilliant chromatography–tandem concretion spectrometry (UPLC-MS/MS).

Methods: [¹³C6]-galactose, [¹³C2]-galactose-1-phosphate, and UDP-glucose were used as substrates for 3 galactose-metabolizing enzymes. The end products from the combined reprisal mixtures, [¹³C6]-galactose-1-phosphate, UDP-[¹³C2]-galactose, and UDP-galactose, were simultaneously quantified using UPLC-MS/MS. Linearity, imprecision, ion suppression, and the effects of substrate were evaluated to influence assay portrayal. Enzyme activities from 35 trim individuals, 8 patients with enzyme deficiency, and 18 mutant cells were analyzed.

Results: Substrates, products, and internal standards from the amalgamating of 3 enzyme reactions were obviously separated by using UPLC-MS/MS, with an injection sequence time of 10 min. Ion hindering was 0.1%–2.5%, the interassay imprecision of UPLC-MS/MS was 3.3%–10.6% CV, and the linearity of each organization was good (R² = 0.994–0.999). Determined samples and mutated cells showed consistently low enzyme activities compared with those of normal individuals and wild-type cells.

Conclusions: This method allows for a high-throughput and reproducible multiplex enzyme assay for galactosemia in erythrocytes.

Background: The diagnosis of galactosemia most of the time involves the square yardage of galactose-1-phosphate uridyltransferase (GALT) labour. Traditional radioactive and fluorescent GALT assays are nonspecific, laborious, and/or lack enough analytical receptiveness. We developed a melted chromatography–tandem mound spectrometry (LC-MS/MS)–based assay for GALT enzyme operation gaging.

Method: Our assay employed durable isotope-labeled - galactose-1-phosphate ([¹³C₆]-Gal-1-P) as an enzyme substrate. Sample cleanup and rupture were achieved by reversed-phase ion-pair chromatography, and the enzymatic product, isotope-labeled uridine diphosphate galactose ([¹³C₆]-UDPGal), was detected by MS/MS at mass change-over (571 > 323) and quantified by use of [¹³C₆]-Glu-1-P (265 > 79) as an internal emblem.

Results: The method yielded a ways (SD) GALT enzyme vocation of 23.8 (3.8) µmol · (g Hgb)^–1 · h^–1 in erythrocyte extracts from 71 controls. The limit of quantification was 0.04 µmol · (g Hgb)^–1 · h^–1 (0.2% of ordinary self-restraint value). Intraassay imprecision was tenacious at 4 unusual levels (100%, 25%, 5%, and 0.2% of the average self-discipline values), and the CVs were deliberate to be 2.1%, 2.5%, 4.6%, and 9.7%, severally (n = 3). Interassay imprecision CVs were 4.5%, 6.7%, 8.2%, and 13.2% (n = 5), separately. The assay recoveries at the 4 levels were higher than 90%. The visible K_m of the 2 substrates, Gal-1-P and UDPGlc, were fixed to be 0.38 mmol/L and 0.071 mmol/L, separately. The assay in erythrocytes of 33 patients with weighty galactosemia revealed no detectable vocation.

Conclusions: This LC-MS/MS–based assay for GALT enzyme vim will be salutary for the diagnosis and lucubrate of biochemically heterogeneous patients with galactosemia, conspicuously those with uncommon genotypes and detectable but low leftover activities.