Electrochemical Biosensor Using Nitrogen-Doped Graphene/Au Nanoparticles/DNAzyme for Ca2+ Determination

An electrochemical biosensor for detecting Ca2+ concentration was proposed using glass carbon electrodes (GCEs) modified with nitrogen-doped graphene (NGR), gold nanoparticles (AuNPs) and DNAzyme. The resistance signal was amplified through two methods: electrochemical reduction of AuNPs on the NGR surface to increase the specific surface area of the electrode and strengthen the adsorption of DNAzyme; and increasement of the DNAzyme base sequence. The process of electrode modification was characterized by scanning electron microscopy, Raman spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Experimental parameters’ influence, such as the deposition time of gold nanoparticles and the detection time, were assessed by electrochemical methods. The linear ranges of the electrochemical biosensor were in the range from 5 × 10−6 to 5 × 10−5 and 5 × 10−5 to 4 × 10−4 M, with a detection limit of 3.8 × 10−6 M. The concentration of Ca2+ in the serum of dairy cows was determined by the biosensor with satisfactory results, which could be potentially used to diagnose subclinical hypocalcemia

Superhydrophobic Paper-Based Microfluidic Field-Effect Transistor Biosensor Functionalized with Semiconducting Single-Walled Carbon Nanotube and DNAzyme for Hypocalcemia Diagnosis

Hypocalcemia is caused by a sharp decline in blood calcium concentration after dairy cow calving, which can lead to various diseases or even death. It is necessary to develop an inexpensive, easy-to-operate, reliable sensor to diagnose hypocalcemia. The cellulose-paper-based microfluidic field-effect biosensor is promising for point-of-care, but it has poor mechanical strength and a short service life after exposure to an aqueous solution. Octadecyltrichlorosilane (OTS), as a popular organosilane derivative, can improve the hydrophobicity of cellulose paper to overcome the shortage of cellulose paper. In this work, OTS was used to produce the superhydrophobic cellulose paper that enhances the mechanical strength and short service life of MFB, and a microfluidic field-effect biosensor (MFB) with semiconducting single-walled carbon nanotubes (SWNTs) and DNAzyme was then developed for the Ca2+ determination. Pyrene carboxylic acid (PCA) attached to SWNTs through a non-covalent π-π stacking interaction provided a carboxyl group that can bond with an amino group of DNAzyme. Two DNAzymes with different sensitivities were designed by changing the sequence length and cleavage site, which were functionalized with SPFET/SWNTs-PCA to form Dual-MFB, decreasing the interference of impurities in cow blood. After optimizing the detecting parameters, Dual-MFB could determine the Ca2+ concentration in the range of 25 μM to 5 mM, with a detection limit of 10.7 μM. The proposed Dual-MFB was applied to measure Ca2+ concentration in cow blood, which provided a new method to diagnose hypocalcemia after dairy cow calving

Expression of Nrf2 Promotes Schwann Cell-Mediated Sciatic Nerve Recovery in Diabetic Peripheral Neuropathy

Background/Aims: High glucose-induced oxidative stress and inflammatory responses play an important role in painful diabetic neuropathy by activating the TLR4/NFκB signal pathway. Schwann cells (SCs) are integral to peripheral nerve biology, contributing to saltatory conduction along axons, nerve and axon development, and axonal regeneration. SCs provide a microenvironment favoring vascular regeneration but their low survival ratio in hyperglycemic conditions suppress the function to promote nerve growth. Nuclear factor erythroid 2-related factor 2 (Nrf2) promotes remyelination after peripheral nerve injury. The aim of this study was to identify the role of Nrf2 in SC-mediated functional recovery after sciatic nerve injury. Methods: We compared plasma inflammatory factors in diabetic patients (DN) with/without diabetic peripheral neuropathy (DPN) and assessed whether Nrf2 expression in SCs could repair peripheral nerve injury in a rat model. Nrf2, TLR4/NFκB signal pathway and apoptosis relative protein expression were detected by western blot. Apoptosis and angiogenesis were determined by immunofluorescence and tubule formation assay, respectively. Regenerated nerves were determined by transmission electron microscope. Results: Higher levels of inflammatory factors and VEGF expression were found in DPN patients. Cellular experiments indicate that Nrf2 expression inhibits hyperglycemia-induced apoptosis and promotes angiogenesis by regulating the TLR4/NFκB signal pathway. Animal experiments show that nerve conduction velocity, myelin sheath thickness, and sciatic vasa nervorum are restored with transplantation of SCs overexpressing Nrf2. Conclusions: Taken together, the high survival ratio of SCs in a DPN rat model indicates that overexpression of Nrf2 restores nerve injury

Combined effects of vitamin B12 and fumarate on rumen propionate production and methanogenesis in dairy cow in vitro

Abstract This study explored the combined effects of vitamin B12 and fumarate supplementation on methane (CH4) emission and propionate synthesis in dairy cows through simulated rumen fermentation in vitro. The experimental animals were 3 cows with an average milk yield of 23 ± 2.8 kg/d, a body weight of 618 ± 100 kg, and a parity of 3 ± 1 that were selected as rumen fluid donors. The TMR diet fed to cows is a fermentation substrate. Experiments adopted 2 × 2 factorial design, including control group, vitamin group (1 mg/g DM vitamin B12), fumarate group (100 mg/g DM), and combined addition group (1 mg/g DM vitamin B12 and 100 mg/g DM). All treatments had no effect on the dry matter degradation (DMD). Both vitamin B12 and fumarate reduced CH4 emission, increased the propionate concentration, and reduced the acetate/propionate ratio without any observed interaction. Vitamin B12 made Prevotella and Prevotellaceae_ UCG‐003 increase in quantity, and fumarate increased the abundance of Succinivibrionaceae_UCG‐002 and Selenomonas, both of which are propionate‐producing bacteria. At the species level, the supplementation of vitamin B12 and fumarate slightly changed the abundance of some strains, but it was not statistically significant. Shifts in the abundance of propionate‐producing bacteria and methanogenic archaea species suggest an increase in propionate production and a decrease in CH4 emission. In conclusion, the addition of vitamin B12 and fumarate changed the fermentation mode of the rumen and reduced the emission of CH4 by affecting the structure of the rumen microbial community, but no obvious interaction was found between the two

High Concentrations of Atmospheric Ammonia Induce Alterations in the Hepatic Proteome of Broilers (<i>Gallus gallus</i>): An iTRAQ-Based Quantitative Proteomic Analysis

<div><p>With the development of the poultry industry, ammonia, as a main contaminant in the air, is causing increasing problems with broiler health. To date, most studies of ammonia toxicity have focused on the nervous system and the gastrointestinal tract in mammals. However, few detailed studies have been conducted on the hepatic response to ammonia toxicity in poultry. The molecular mechanisms that underlie these effects remain unclear. In the present study, our group applied isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomic analysis to investigate changes in the protein profile change in hepatic tissue of broilers exposed to high concentrations of atmospheric ammonia, with the goal of characterizing the molecular mechanisms of chronic liver injury from exposure to high ambient levels of ammonia. Overall, 30 differentially expressed proteins that are involved in nutrient metabolism (energy, lipid, and amino acid), immune response, transcriptional and translational regulation, stress response, and detoxification were identified. In particular, two of these proteins, beta-1 galactosidase (GLB1) and a kinase (PRKA) anchor protein 8-like (AKAP8 L), were previously suggested to be potential biomarkers of chronic liver injury. In addition to the changes in the protein profile, serum parameters and histochemical analyses of hepatic tissue also showed extensive hepatic damage in ammonia-exposed broilers. Altogether, these findings suggest that longtime exposure to high concentrations of atmospheric ammonia can trigger chronic hepatic injury in broilers via different mechanisms, providing new information that can be used for intervention using nutritional strategies in the future.</p></div

List of differentially expressed nutrients metabolic proteins in hepatic samples from treatment group and control group.

<p>A total of 30 proteins of differential abundance were grouped into eight classes based on putative functions. Protein expressions are represented as log₂ fold change relative to the control</p><p>List of differentially expressed nutrients metabolic proteins in hepatic samples from treatment group and control group.</p

qPCR validation of eight proteins of differential abundance from the hepatic tissues of 42-day-old AA broilers at the mRNA level (A, B, C, D, E, F, G and H).

<p>Samples were normalized with the reference gene β-actin. Data are presented as means ± S.D (n = 6 per group). Mean values with different superscript letters (^{a, b}) are significantly different (<i>P</i> < 0.05).</p