Effect of combination of high-intensity ultrasound treatment and dextran glycosylation on structural and interfacial properties of buckwheat protein isolates

This study investigated the effects of high-intensity ultrasound and glycosylation on the structural and interfacial properties of the Maillard reaction conjugates of buckwheat protein isolate (BPI). The covalent attachment of dextran to BPI was confirmed by examination of the Fourier-transform infrared spectra. Emulsifying properties of the conjugates obtained by ultrasound treatment were improved as compared to those obtained by classical heating. Structural feature analyses suggested that conjugates obtained by ultrasound treatment had less α-helix and more random coil, higher surface hydrophobicity and less compact tertiary structure as compared to those obtained by classical heating. The surface activity measurement revealed that the BPI–dextran conjugates obtained by ultrasound treatment were closely packed and that each molecule occupied a small area of the interface. Combination of ultrasonic treatment and glycosylation was proved to be an efficient way to develop new stabilizers and thickening agents for food in this study.     

Statistical Inference Methods for Two Crossing Survival Curves: A Comparison of Methods

A common problem that is encountered in medical applications is the overall homogeneity of survival distributions when two survival curves cross each other. A survey demonstrated that under this condition, which was an obvious violation of the assumption of proportional hazard rates, the log-rank test was still used in 70% of studies. Several statistical methods have been proposed to solve this problem. However, in many applications, it is difficult to specify the types of survival differences and choose an appropriate method prior to analysis. Thus, we conducted an extensive series of Monte Carlo simulations to investigate the power and type I error rate of these procedures under various patterns of crossing survival curves with different censoring rates and distribution parameters. Our objective was to evaluate the strengths and weaknesses of tests in different situations and for various censoring rates and to recommend an appropriate test that will not fail for a wide range of applications. Simulation studies demonstrated that adaptive Neyman’s smooth tests and the two-stage procedure offer higher power and greater stability than other methods when the survival distributions cross at early, middle or late times. Even for proportional hazards, both methods maintain acceptable power compared with the log-rank test. In terms of the type I error rate, Renyi and Cramér—von Mises tests are relatively conservative, whereas the statistics of the Lin-Xu test exhibit apparent inflation as the censoring rate increases. Other tests produce results close to the nominal 0.05 level. In conclusion, adaptive Neyman’s smooth tests and the two-stage procedure are found to be the most stable and feasible approaches for a variety of situations and censoring rates. Therefore, they are applicable to a wider spectrum of alternatives compared with other tests.     

Characterization of Cre recombinase mouse lines enabling cell type-specific targeting of postnatal intervertebral discs

Cre/loxP technology is an important tool for studying cell type-specific gene functions. Cre recombinase mouse lines, including Agc1-CreER^T2, Col2a1-Cre; Col2a1-CreER^T2, Shh-Cre, Shh-CreER^T2, and Osx-Cre, have been proven to be valuable tools to elucidate the biology of long bones, yet the information for their activity in postnatal intervertebral disc (IVD) tissues was very limited. In this study, we used R26-mTmG fluorescent reporter to systematically analyze cell specificity and targeting efficiency of these six mouse lines in IVD tissues at postnatal growing and adult stages. We found that Agc1-CreER^T2 is effective to direct recombination in all components of IVDs, including annulus fibrosus (AF), nucleus pulposus (NP), and cartilaginous endplate (CEP), upon tamoxifen induction at either 2 weeks or 2 months of ages. Moreover, Col2a1-Cre targets most of the cells in IVDs, except for some cells in the outer AF (OAF) and NP. In contrast, the activity of Col2a1-CreER^T2 is mainly limited to the IAF of IVD tissues at either stage of tamoxifen injection. Similarly, Shh-Cre directs recombination specifically in all NP cells, whereas Shh-CreER^T2 is active only in a few NP cells when tamoxifen is administered at either stage. Finally, Osx-Cre targets cells in the CEP, but not in the NP or AF of IVDs tissues at these two stages. Thus, our data demonstrated that all these Cre lines can direct recombination in IVD tissues at postnatal stages with different cell type specificity and/or targeting efficiency, and can, therefore, serve as valuable tools to dissect cell type-specific gene functions in IVD development and homeostasis.     

Identification and characterization of a chondroitin synthase from Avibacterium paragallinarum

Applied Microbiology and Biotechnology - Avibacterium paragallinarum is a Gram-negative bacterium that causes infectious coryza in chicken. It was reported that the capsule polysaccharides...     

Biotransformation of menadione to its prenylated derivative MK-3 using recombinant <Emphasis Type="Italic">Pichia pastoris</Emphasis>

Prenylated quinones, especially menaquinones, have significant physiological activities, but are arduous to synthesize efficiently. Due to the relaxed aromatic substrate specificity and prenylation regiospecificity at the ortho- site of the phenolic hydroxyl group, the aromatic prenyltransferase NovQ from Streptomyces may be useful in menaquinone synthesis from menadione. In this study, NovQ was overexpressed in Pichia pastoris. After fermentation optimization, NovQ production increased by 1617%. Then the different effects of metal ions, detergents and pH on the activity of purified NovQ were investigated to optimize the prenylation reaction. Finally, purified NovQ and cells containing NovQ were used for menadione prenylation in vitro and in vivo, respectively. Menaquinone-1 (MK-1) was detected as the only product in vitro with γ,γ-dimethylallyl pyrophosphate and menadione hydroquinol substrates. MK-3 at a concentration of 90.53 mg/L was detected as the major product of whole cell catalysis with 3-methyl-2-buten-1-ol and menadione hydroquinol substrates. This study realized whole cell catalysis converting menadione to menaquinones.     

Enhancing Fusarium crown rot resistance by pyramiding large-effect QTL in common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Fusarium crown rot (FCR) has become one of the most damaging cereal diseases in semi-arid regions worldwide. Targeting three large-effect QTL (located on the chromosome arm 3BL, 5DS and 2DL, respectively), we investigated the feasibility of enhancing FCR resistance by gene pyramiding. Significant effects were detected for each of the three QTL in both populations assessed. Lines with any combination of two resistant alleles gave significantly better resistance than those with a single resistant allele only and those without any allele, and lines possessing all three resistant alleles showed the best resistance. These results demonstrated that gene pyramiding can be an effective approach in improving FCR resistance. Those lines with resistant alleles from all three QTL could be valuable genetic stocks for breeding programs.     

18F-EF5 PET Is Predictive of Response to Fractionated Radiotherapy in Preclinical Tumor Models

We evaluated the relationship between pre-treatment positron emission tomography (PET) using the hypoxic tracer ¹⁸F-[2-(2-nitro-1-H-imidazol-1-yl)-N-(2,2,3,3,3- pentafluoropropyl) acetamide] (¹⁸F-EF5) and the response of preclinical tumor models to a range of fractionated radiotherapies. Subcutaneous HT29, A549 and RKO tumors grown in nude mice were imaged using ¹⁸F-EF5 positron emission tomography (PET) in order to characterize the extent and heterogeneity of hypoxia in these systems. Based on these results, 80 A549 tumors were subsequently grown and imaged using ¹⁸F-EF5 PET, and then treated with one, two, or four fraction radiation treatments to a total dose of 10–40 Gy. Response was monitored by serial caliper measurements of tumor volume. Longitudinal post-treatment ¹⁸F-EF5 PET imaging was performed on a subset of tumors. Terminal histologic analysis was performed to validate ¹⁸F-EF5 PET measures of hypoxia. EF5-positive tumors responded more poorly to low dose single fraction irradiation relative to EF5-negative tumors, however both groups responded similarly to larger single fraction doses. Irradiated tumors exhibited reduced ¹⁸F-EF5 uptake one month after treatment compared to control tumors. These findings indicate that pre- treatment ¹⁸F-EF5 PET can predict the response of tumors to single fraction radiation treatment. However, increasing the number of fractions delivered abrogates the difference in response between tumors with high and low EF5 uptake pre-treatment, in agreement with traditional radiobiology.     

MiR‐122 modification enhances the therapeutic efficacy of adipose tissue‐derived mesenchymal stem cells against liver fibrosis

Mesenchymal stem cell (MSC) transplantation alone may be insufficient for treatment of liver fibrosis because of complicated histopathological changes in the liver. Given that miR‐122 plays an essential role in liver fibrosis by negatively regulating the proliferation and transactivation of hepatic stellate cells (HSCs), this study investigated whether miR‐122 modification can improve the therapeutic efficacy of adipose tissue‐derived MSCs in treating liver fibrosis. MiR‐122‐modified AMSCs (AMSC‐122) were constructed through lentivirus‐mediated transfer of pre‐miR‐122. MiR‐122‐modified AMSCs expressed high level of miR‐122, while they retained their phenotype and differentiation potential as naïve AMSCs. AMSC‐122 more effectively suppressed the proliferation of and collagen maturation in HSCs than scramble miRNA‐modified AMSCs. In addition, AMSC‐derived exosomes mediated the miR‐122 communication between AMSCs and HSCs, further affecting the expression levels of miR‐122 target genes, such as insulin‐like growth factor receptor 1 (IGF1R), Cyclin G(1) (CCNG1) and prolyl‐4‐hydroxylase α1 (P4HA1), which are involved in proliferation of and collagen maturation in HSCs. Moreover, miR‐122 modification enhanced the therapeutic efficacy of AMSCs in the treatment of carbon tetrachloride (CCl₄)‐induced liver fibrosis by suppressing the activation of HSCs and alleviating collagen deposition. Results demonstrate that miR‐122 modification improves the therapeutic efficacy of AMSCs through exosome‐mediated miR‐122 communication; thus, miR‐122 modification is a new potential strategy for treatment of liver fibrosis.     

Effects of dietary protein intake on the oxidation of glutamate,glutamine, glucose and palmitate in tissues of largemouth bass (Micropterus salmoides)

Largemouth bass (Micropterus salmoides, a carnivorous fish native to North America) prefers to utilize amino acids as energy sources rather than glucose and fatty acids. However, little is known about the nutritional regulation of substrate oxidation in the fish. Therefore, this study was conducted to determine whether the oxidation of glutamate, glutamine, glucose and palmitate in its tissues might be influenced by dietary protein intake. Juvenile largemouth bass (initial weight 18.3 ± 0.1 g) were fed three isocaloric diets containing 40%, 45% and 50% protein for 8 weeks. The growth performance, energy retention, and lipid retention of juvenile fish increased with increasing dietary protein levels. The rate of oxidation of glutamate by the intestine was much greater than that of glutamine, explaining why increasing the dietary protein content from 40% to 50% had no effect on the serum concentration of glutamate but increased that of glutamine in the fish. The liver of fish fed the 50% protein diet had a higher (P < 0.05) rate of glutamine oxidation than that in the 40% and 45% protein groups. In contrast, augmenting dietary protein content from 40% to 45% increased (P < 0.05) both glutamine and glutamate oxidation in the proximal intestine of the fish and renal glutamine oxidation, without changes in intestinal or renal AA oxidation between the 45% and 50% protein groups. Furthermore, the rates of glucose oxidation in the liver, kidney, and intestine of largemouth bass were decreased in response to an  increase in dietary  protein content   from 40% to 45% and a concomitant decrease in dietary starch content from 22.3% to 15.78%, but did not differ between the 45% and 50% protein groups.   The rates of oxidation of glucose in skeletal muscle and those of palmitate in all tissues (except for the  kidney) were not affected by the diets. Collectively, these results indicate that the largemouth bass can regulate substrate metabolism in a  tissue-specific manner to favor protein and lipid gains as dietary protein content increases from 40% to 50% and have a lower ability to oxidize fatty acids and glucose than amino acids regardless of the dietary protein intake.