Immunity transfer in mule foals fed with good IgG quality colostrum

While the passive transfer of immunity in horse and donkey foals has been extensively studied, there is limited information for mule foals. Immunoglobulin type G (IgG) and serum total protein concentration (TP) were assessed at different sampling times to evaluate the correlation between serum radial immunodiffusion (SRID) with electrophoresis, refractometry, and dry chemistry analyzer (Biuret), and to estimate serum IgG concentrations using serum TP in mule foals. We analyzed a total of 30 samples collected at birth, and at 6, 12, 24, and 48 h of life from 6 mule foals by SRID, electrophoresis TP, biuret TP, and refractometry TP. The SRID IgG concentration significantly increased from birth until T6 (p < 0.001). Serum TP analyzed with refractometry revealed differences between T0 and T12, T24 and T48 (p < 0.05), while a significant difference was observed with the biuret method between T0 and all the other sampling times (p < 0.001). A strong correlation was found between IgG SRID and biuret TP (r = 0.69, p < 0.001), and a good correlation existed between IgG SRID, refractometry TP, and electrophoresis TP (r = 0.44, p < 0.01 and r = 0.39, p < 0.05, respectively). All methods can be used to estimate the passive transfer of immunity in mule foals. TP refractometry and biuret TP values can be used to determine serum IgG concentrations in the blood of mule foals on their first day of life through the application of a specific equation.

Ultrathin porous graphitic carbon nitride from recrystallized precursor toward significantly enhanced photocatalytic water splitting

Structure regulation (including electronic structure and morphology) for graphitic carbon nitride (g-C₃N₄) is an effective way to promote the photocatalytic activity. Herein, an ultrathin porous g-C₃N₄ (BCN-HT100) was synthesized by calcination of biuret hydrate. Hydrothermal treatment induced biuret recrystallization to form biuret hydrate precursor with regular morphology and large crystal size, thus promoting the polymerization of melem to form g-C₃N₄ network. Accordingly, BCN-HT100 possessed ultrathin nanosheet structure, higher polymerization degree, larger surface area and more pores than biuret-derived g-C₃N₄. BCN-HT100 behaved high-efficiency photocatalytic H₂-productin activity with an apparent quantum yield (AQY) of 58.7% at 405 nm due to the enhanced utilization efficiency for photo-generated charge carriers and abundant reactive sites. Furthermore, Pt-NiCo₂O₄ dual cocatalysts were employed on BCN-HT100 for achieving photocatalytic overall water splitting, and the AQY reached 4.9% at 405 nm. This work provides a meaningful reference to designing g-C₃N₄ to achieve efficient solar energy conversion into hydrogen.

A Procedure for Removal of Cyanuric Acid in Swimming Pools Using a Cell-Free Thermostable Cyanuric Acid Hydrolase

Cyanuric acid (CYA) is used commercially for maintaining active chlorine to inactivate microbial and viral pathogens in swimming pools and hot tubs. Repeated CYA addition can cause a lack of available chlorine and adequate disinfection. Acceptable CYA levels can potentially be restored via cyanuric acid hydrolases (CAH), enzymes that hydrolyze CYA to biuret under mild conditions. Here we describe a previously unknown CAH enzyme from Pseudolabrys sp. Root1462 (CAH-PR), mined from public databases by bioinformatic analysis of potential CAH genes, which we show to be suitable in a cell-free form for industrial applications based upon favorable enzymatic and physical properties, combined with high-yield expression in aerobic cell culture. The kinetic parameters and modeled structure were similar to known CAH enzymes, but the new enzyme displayed a surprising thermal and storage stability. The new CAH enzyme was applied, following addition of inexpensive sodium sulfite, to hydrolyze CYA to biuret. At the desired endpoint, hypochlorite addition inactivated remaining enzyme and oxidized biuret to primarily dinitrogen and carbon dioxide gases. The mechanism of biuret oxidation with hypochlorite under conditions relevant to recreational pools is described.

Comparison of tests for failure of passive transfer in neonatal calf serum using total protein refractometry and the biuret method

Failure of passive transfer (FPT) is defined as failure to absorb colostral antibodies sufficient to achieve a serum Immunoglobulin G (IgG) concentration >10 g/L. Immunoglobulin G can be measured directly in calf serum using radial immunodiffusion (RID), or indirectly estimated by measuring total protein (TP). Indirect TP measures are usually favoured because of their relatively lower costs. The aim of this work was to compare TP measurements using refractometry and biuret methods against the reference RID test in neonatal dairy calves, and to assess agreement between these indirect measures. Neither the biuret nor the refractometer method provided a high sensitivity for detection of FPT, as defined by RID. There was no systematic difference between the methods in their estimation of TP, although the biuret method was more accurate than the refractometer method when tested against the reference RID test (accuracy = 83.1 % v 69.3 %) and the refractometer was more likely to overestimate the number of calves with FPT. Specificity for the biuret test was 93.9 % compared with the refractometer specificity of 74.4 %. Mean TP as estimated by the biuret method was higher than the mean TP estimated by the refractometer (6.25 g/dL versus 5.52 g/dL), and the Pearson correlation coefficient for the two assays was only moderate, at 0.58. This suggests that the biuret method is preferable to the refractometer for detecting FPT in calves, despite the superior convenience of the refractometer.

Development and Validation of a HPLC-UV Method for Urea and Related Impurities

Urea is used in biopharmaceutical manufacturing processes for the purification of therapeutic proteins, for cleaning columns, and for refolding proteins after purification. The urea used for such purposes is typically USP grade material obtained from commercial sources and further characterization is required prior to use, such as determination of purity and identity. For this purpose, a robust analytical method is needed that can characterize the known organic impurities of urea. However, the existing methods show high assay variability and are not able to resolve all known organic impurities as desired for accurate quantification. In the present manuscript we developed a new high-performance liquid chromatography method with UV detection for the separation of urea and its impurities (biuret, cyanuric acid, and triuret). The method performance characteristics evaluated for urea and biuret were specificity, linearity, accuracy, identity, precision, and robustness and the newly developed method met all predefined performance acceptance criteria.

Deactivation of Cu-SAPO-34 by urea-related deposits at low temperatures and the regeneration

Selective catalytic reduction (SCR) with urea catalyzed by Cu-SAPO-34 is an effective method to eliminate NO_x from diesel exhaust. However, urea-related deposits may form during cold-start and urban driving due to low exhaust temperatures. The activity of Cu-SAPO-34 at 175°C is significantly degraded by urea exposure, and 300°C is required for regeneration. Through in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed hydrolysis studies, the dominant stable deposit at 175°C is identified as biuret, which can be eliminated at 300°C. The urea-derived deactivation and regeneration mechanisms of Cu-SAPO-34 were compared with those of anatase-supported catalysts.

Clinical performance evaluation of total protein measurement by digital refractometry and characterization of non-protein solute interferences

OBJECTIVES

Refractometric methods to measure total protein (TP) in serum and plasma specimens have been replaced by automated biuret methods in virtually all routine clinical testing. A subset of laboratories, however, still report using refractometry to measure TP in conjunction with serum protein electrophoresis. The objective of this study was therefore to conduct a modern performance evaluation of a digital refractometer for TP measurement.

DESIGN AND METHODS

Performance evaluation of a MISCO Palm Abbe™ digital refractometer was conducted through device familiarization, carryover, precision, accuracy, linearity, analytical sensitivity, analytical specificity, and reference interval verification. Comparison assays included a manual refractometer and an automated biuret assay.

RESULTS

Carryover risk was eliminated using a demineralized distilled water (ddH₂O) wash step. Precision studies demonstrated overall imprecision of 2.2% CV (low TP pool) and 0.5% CV (high TP pool). Accuracy studies demonstrated correlation to both manual refractometry and the biuret method. An overall positive bias (+5.0%) was observed versus the biuret method. On average, outlier specimens had an increased triglyceride concentration. Linearity was verified using mixed dilutions of: a) low and high concentration patient pools, or b) albumin-spiked ddH₂O and high concentration patient pool. Decreased recovery was observed using ddH₂O dilutions at low TP concentrations. Significant interference was detected at high concentrations of glucose (>267 mg/dL) and triglycerides (>580 mg/dL). Current laboratory reference intervals for TP were verified.

CONCLUSIONS

Performance characteristics of this digital refractometer were validated in a clinical laboratory setting. Biuret method remains the preferred assay for TP measurement in routine clinical analyses.

Development and Validation of a High-Performance Liquid Chromatography Method With UV Detection for Determination of 1-(2-phenylethyl)-5- (quinaldin-4-yl) Biuret in Rat Plasma

BACKGROUND

Recently, biuret derivatives have been reported as showing moderate to good cytotoxic effect against certain cancer cell lines. In this study, a high-performance liquid chromatography method was developed for determination of 1-(2-phenylethyl)-5-(quinaldin-4-yl) biuret (PEQB) in rat plasma to use in future studies on this compound and related derivatives.

OBJECTIVES

In this study, we describe a simple and sensitive high-performance liquid chromatography method with UV detection for determination of 1-(2-phenylethyl)-6-(quinaldin-4-yl) biuret (PEQB) in rat plasma.

MATERIALS AND METHODS

Separations were performed on a Nucleosil-100 CN HPLC column (125 × 4.0 mm) (5 µm), using a mixture of acetonitrile: methanol: potassium dihydrogen phosphate buffer (0.05 M, pH 3.5) (10:10:80) as mobile phase delivered at a flow rate of 1 mL/minute. Detection of PEQB and internal standard (1-([[3-(1,3-benzothiazol-2-ylsulfanyl)propyl]carbamoyl]amino)-N-phenylformamide) was performed at 235 nm and ambient temperature. Plasma samples (200 µL) were prepared by addition of 40 µL internal standard (100 µg/mL), and 400 µL acetonitrile. After vortex mixing and centrifugation at 10000 g, 50 µL of the clear supernatant was directly injected onto the chromatography column. Calibration curves were constructed by fitting the peak area ratio of the biuret to internal standard against concentration of biuret to a power model using generalized least squares nonlinear regression method.

RESULTS

Under the above chromatography condition, biuret compound (PEQB) and the internal standard were detected at 4.5 and 13.5 minutes, respectively. Limit of quantitation of the PEQB was 0.1 µg/mL. Accuracy of the method over the concentration range of 0.1-100 µg/mL was between 88-109%. Inter- and intraday precisions were 4-19% and 6-8%, respectively. A good relationship in the form of a power model was found for two separate concentration ranges of 0.1-1 and 2.5-100 µg/mL (R (2)> 0.99).

CONCLUSIONS

The presented simple HPLC method is sufficiently accurate, precise and sensitive for the quantitation of 1-(2-phenylethyl)-5-(quinaldin-4-yl) biuret in rat plasma.