Effects of Maillard reaction of different monosaccharide-modified on some functional properties of fish gelatin.

In this work, the effects of Maillard reaction of different monosaccharide-modified fish gelatin were studied. The changes of gel properties, rheology and structure of fish gelatin before and after modification were compared and analyzed, and oil-in-woter emulsions were prepared. The results showed that the five-carbon monosaccharide had stronger modification ability than the six-carbon monosaccharide, which was mainly due to the different steric hindrance of the amino acids in the nuclear layer and the outer layer to the glycosylation reaction. With the progress of the Maillard reaction, the color of fish gelatin gradually became darker. The attachment of sugar chains inhibited the gelation process of fish gelatin, decreased the gelation rate, changed the secondary structure, increased the content of ß-turn or α-helix, increased the degree of fluorescence quenching, and enhanced the emulsifying properties and emulsion stability. This study provides useful information for the preparation of different types of monosaccharide-modified proteins and emulsions.

Fibulin-2: A potential regulator of immune dysfunction after bone trauma.

OBJECTIVES: To reveal the relationship between the fibulin-2 protein and immune dysfunction after bone trauma. METHODS: Individuals who were admitted to the study were divided into a bone trauma group, a recovered from bone trauma group and a volunteer without bone trauma group based on the reason for admission. Fibulin-2 levels in the three groups were compared. Fibulin-2-knockout (fibulin-2-/- ) mice and wild-type (WT) mice were used to detect susceptibility to infection. Hematoxylin and eosin (HE) staining and immunohistochemical staining were employed to observe pathological changes in each organ from fibulin-2-/- mice and WT mice. RESULTS: In total, 132 patients were enrolled in this study. The fibulin-2 level in the bone trauma group was lower than that in the recovered bone trauma group (3.39 ± 1.41 vs. 4.30 ± 1.38 ng/mL, t = 2.948, p < .05) and also lower than that in the volunteers without bone trauma group (3.39 ± 1.41 vs. 4.73 ± 1.67 ng/mL, t = 4.135, p < .05). Fibulin-2-/- mice are more prone to infection. Compared with those in WT mice, spleen function and thymus function in fibulin-2-/- mice were impaired. Immunohistochemical staining revealed that compared with those in WT mice, significantly fewer CD4+ T cells, CD8+ T cells, and CD19+ B cells were noted in the spleen and thymus of fibulin-2-/- mice. CONCLUSIONS: The plasma fibulin-2 level was lower in patients with bone trauma. Decreased fibulin-2 is associated with immune dysfunction after bone trauma.

Fibulin2: a negative regulator of BMSC osteogenic differentiation in infected bone fracture healing.

Bone fracture remains a common occurrence, with a population-weighted incidence of approximately 3.21 per 1000. In addition, approximately 2% to 50% of patients with skeletal fractures will develop an infection, one of the causes of disordered bone healing. Dysfunction of bone marrow mesenchymal stem cells (BMSCs) plays a key role in disordered bone repair. However, the specific mechanisms underlying BMSC dysfunction caused by bone infection are largely unknown. In this study, we discovered that Fibulin2 expression was upregulated in infected bone tissues and that BMSCs were the source of infection-induced Fibulin2. Importantly, Fibulin2 knockout accelerated mineralized bone formation during skeletal development and inhibited inflammatory bone resorption. We demonstrated that Fibulin2 suppressed BMSC osteogenic differentiation by binding to Notch2 and inactivating the Notch2 signaling pathway. Moreover, Fibulin2 knockdown restored Notch2 pathway activation and promoted BMSC osteogenesis; these outcomes were abolished by DAPT, a Notch inhibitor. Furthermore, transplanted Fibulin2 knockdown BMSCs displayed better bone repair potential in vivo. Altogether, Fibulin2 is a negative regulator of BMSC osteogenic differentiation that inhibits osteogenesis by inactivating the Notch2 signaling pathway in infected bone.

Sensitive immunoassays based on a monoclonal antibody for detection of marbofloxacin in milk.

Marbofloxacin (MBF) is a key class of synthetic fluoroquinolone antibiotic that is commonly used as a veterinary drug. However, excess residue of MBF in animal-derived food samples, such as milk, is harmful to consumers. In this study, 4 mAb against MBF, namely, M4E3, M7A6, M3C7, and M5C6, were produced. Indirect competitive (ic) ELISA revealed that the M4E3 exhibited the highest sensitivity with a half-maximal inhibitory concentration (IC50) of 0.07 ng/mL and a limit of detection of 0.01 ng/mL for detection of MBF. The results of the cross-reactivity experiment revealed that the M4E3 could detect lomefloxacin, ofloxacin, fleroxacin, pefloxacin, danofloxacin, and enrofloxacin sensitively with IC50 of 0.02, 0.07, 0.18, 0.27, 0.30, and 0.32 ng/mL, respectively. Meanwhile, a cross-reactivity experiment showed that the M4E3 had a crossover rate of more than 20% with these fluoroquinolone analogs. A weak crossover rate below 1.11% was observed with 14 other fluoroquinolone analogs. The recovery rate of MBF in milk ranged from 72.28% to 129.19%, which showed that the developed indirect competitive ELISA was effective in detecting MBF in milk. Furthermore, a visual colloidal gold-based immunochromatographic assay was developed for detecting MBF with a cut-off value of 1 ng/mL in both phosphate-buffered saline and a milk sample by using this mAb. Given this sensitive mAb, both indirect competitive ELISA and colloidal gold-based immunochromatographic assay could be effective screening tools for detection of MBF in milk.

Preparation of an Antidanofloxacin Monoclonal Antibody and Development of Immunoassays for Detecting Danofloxacin in Meat.

Danofloxacin (DAF), a third-generation fluroquinolone (FQ), is widely used as a broad-spectrum antibacterial drug to prevent diseases in livestock and poultry. In this study, a highly specific and sensitive monoclonal antibody (mAb) against DAF was prepared. Also, the mAb was used for the indirect competitive enzyme-linked immunosorbent assay (icELISA) and immunochromatographic strip for the detection of DAF residues in meat. The IC50 of the icELISA based on this mAb was 1.39 ng/mL, and the limit of detection was 0.2 ng/mL. According to the cross-reactivity (CR) experiment, the ELISA that we developed was highly specific and had low CR with other FQ analogues. Moreover, the cut-off of the immunochromatographic strip developed for detecting DAF in meat was 5 ng/mL. Overall, the developed ELISA and immunochromatographic strip based on the prepared mAb were proved reliable for the rapid detection of DAF in meat and can be considered as effective screening methods for food safety and quality management.

Efficacy and mechanisms underlying the effects of allogeneic umbilical cord mesenchymal stem cell transplantation on acute radiation injury in tree shrews.

Umbilical cord mesenchymal stem cells (UC-MSCs) exert strong immunomodulatory effects and can repair organs. However, their roles in radiation injury remain unclear. We show that in tree shrews with acute radiation injury, injected UC-MSCs significantly improved survival rates, reduced lung inflammation and apoptosis, prevented pulmonary fibrotic processes, recovered hematopoiesis, and increased blood counts. A protein microarray analysis showed that serum levels of the anti-inflammatory cytokines IL-10 and IL-13 and the growth factors BMP-5, BMP-7, HGF, insulin, NT-4, VEGFR3, and SCF were significantly higher, while those of the inflammatory cytokines IL-2, TIMP-2, TNF-α, IFN-γ, IL-1ra, and IL-8 and the fibrosis-related factors PDGF-BB, PDGF-AA, TGF-ß1, IGFBP-2, and IGFBP-4 were significantly lower in UC-MSC-injected animals. A transcriptome analysis of PBMCs showed that the mRNA expression of C1q was upregulated, while that of HLA-DP was downregulated after UC-MSC injection. These results confirm the immunohistochemistry results. eGFP-labeled UC-MSCs were traced in vivo and found in the heart, liver, spleen, lungs, kidneys, thymus, small intestine and bone marrow. Our findings suggest that UC-MSC transplantation may be a novel therapeutic approach for treating acute radiation injury.