Elucidation of potential relationship between endogenous proteases and key flavor substances in dry-cured pork coppa

Dry-cured meat products are considerably popular around the world due to unique flavor.Proteolysis is one of the enzymatic reactions from which flavor substances are derived,which is affected by endogenous proteases.The purpose aimed to reveal the potential relationship between endogenous proteases and key flavor substances in dry-cured pork coppa in this paper.The dynamic changes of endogenous proteases activity,free amino acids,and volatiles during dry-cured pork coppa processing were characterized.The results showed that 5 kinds of free amino acids,Glu,Lys,Val,Ala,and Leu,were identified as significant contributors to taste.Meanwhile,key volatiles,such as hexanal,nonanal,octanal,benzaldehyde,3-methyl butanoic acid,2-methyl propanoic acid,and ethyl octanoate,greatly contributed to the flavor characteristics of dry-cured pork coppa.Further partial correlation analysis was performed to better elucidate the relationship among parameters.The results revealed that close relationship between endogenous proteases and key substances.RAP not only significantly affected the accumulation of key active-amino acids,but also affected the accumulation of ethyl octanoate,2,3-pentanedione,and 2,3-octanedione by regulating the accumulation of octanoic acid and Leu.In addition,cathepsin B and D,DPP II,DPP IV and RAP notably affected accumulation of hexanal.

Edaravone-loaded poly(amino acid) nanogel inhibits ferroptosis for neuroprotection in cerebral ischemia injury

Neurological injury caused by ischemic stroke is a major cause of permanent disability and death. The currently available neuroprotective drugs fail to achieve desired therapeutic efficacy mainly due to short circulation half-life and poor blood−brain barrier (BBB) permeability. For that, an edaravone-loaded pH/glutathione (pH/GSH) dual-responsive poly(amino acid) nanogel (NG/EDA) was developed to improve the neuroprotection of EDA. The nanogel was triggered by acidic and EDA-induced high-level GSH microenvironments, which enabled the selective and sustained release of EDA at the site of ischemic injury. NG/EDA exhibited a uniform sub-spherical morphology with a mean hydrodynamic diameter of 112.3 ± 8.2 nm. NG/EDA efficiently accumulated at the cerebral ischemic injury site of permanent middle cerebral artery occlusion (pMCAO) mice, showing an efficient BBB crossing feature. Notably, NG/EDA with 50 µM EDA significantly increased neuron survival (29.3%) following oxygen and glucose deprivation by inhibiting ferroptosis. In addition, administering NG/EDA for 7 d significantly reduced infarct volume to 22.2% ± 7.2% and decreased neurobehavioral scores from 9.0 ± 0.6 to 2.0 ± 0.8. Such a pH/GSH dual-responsive nanoplatform might provide a unique and promising modality for neuroprotection in ischemic stroke and other central nervous system diseases.

Inhibitory effects of transfected Bcl-XL antisense oligodeoxynucleotide to proliferation and growth in esophageal carcinoma cell line and human esophageal carcinoma xenograft of nude mice

Objective： The aim of our study was to investigate the biological effects of Bcl-XL antisense oligodeoxynucleotide （ASODN） transfected into cultured esophageal carcinoma cells and human esophageal carcinoma xenograft in nude mice. Methods： Cationic liposome-mediated ASODN was used to transfect esophageal carcinoma cells. RT-PCR, Western blot, MTT assay, flow cytometry, and in situ apoptosis cells detection （TUNEL detection） were used to systematically study the biological effects of transfected cells both in vitro and in vivo. Results： In this study, the results showed that the proliferation of esophageal carcinoma cells in ASODN group decreased significantly when compared with the control group （P 〈 0.05）, at 57.3% Bcl-XL mRNA inhibitory rate, and a significant decreasing of Bcl-XL protein expression, at the apoptosis rates of （31.1 ＋ 5.8）% and 35.0% by flow cytometry and TUNEL assay respectively （P 〈 0.01, when compared with control groups）. It also showed that the growth of human esophageal carcinoma in nude mice of ASODN group was significantly inhibited （P 〈 0.05）, together with a significant decreased expression level of Bcl-XL mRNA and protein, and an induced tumor cell apoptosis in nude mice. Conclusion： Our result indicates BcI-XL ASODN can effectively inhibit the proliferation of esophageal carcinoma cells in vitro and tumor growth in vivo. The suppression of Bcl-XL expression by ASODN may offer both a therapeutic approach and an important theoretic foundation for gene therapy against esophageal carcinoma.

Expression of Vascular Endothelial Growth Factor C and Its Clinical Significance in Human Esophageal Squamous Cell Carcinoma

OBJECTIVE To examine the expression of vascular endothelial growth factor C （VEGF-C） in human esophageal squamous cell carcinoma （ESCC）, and to clarify its role in lymphatic metastasis in ESCC patients.METHODS Esophageal carcinoma EC9706 cells and samples from 49 patients with primary ESCC were investigated by using S-P immunohistochemistry （IHC）, the semi-quantitative reverse transcriptase-polymerase chain reaction （RT-PCR） and in situ hybridization （ISH） methods for VEGF-C expression. RESULTS VEGF-C positive expression was found in EC9706 cells through IHC, ISH and RT-PCR. Positive IHC for VEGF-C was observed in 36 of 49 cases of ESCC. There was a significant difference between the expression of VEGF-C in a lymph-node-positive group compared to a node-negative group （χ^2=4.7, P〈0.05）. Positive ISH for VEGF-C mRNA was observed in 23 of 49 cases of ESCC. There was a significant difference between the expression of VEGF-C in the lymph-node-positive group and node-negative group （χ^2=31.3, P〈0.01）. The expression of VEGF-C was significantly higher in the lymph-node-positive group compared to the node-negative group. Of 49 ESCC tissues, RT-PCR for VEGF-C mRNA was observed positively in 29 cases. There was a significant difference between the expression of VEGF-C in the lymph-node-positive group and node-negative group （χ^2=23.3, P〈0.01）. The expression of VEGF-C was significantly higher in the lymphnode-positive group compared to the node-negative group. Expressions of VEGF-C were not significantly associated with age, gender, and pathological grade. There was a relationship between VEGF-C mRNA expressions by RT-PCR and ISH （χ^2=18.5, P〈0.01） in ESCC cases, but with no significant difference between the two methods. CONCLUSION VEGF-C expression may induce lymphangiogenesis in human ESCC. There was a close correlation between VEGF-C expression and lymph node metastasis. VEGF-C can serve as a useful prognostic factor for ESCC patients.

Effects of ammonia concentration in hydrothermal treatment on structure and redox properties of cerium zirconium solid solution

Cerium zirconium solid solution is a key washcoat material for automotive three-way catalysts(TWCs).However,improving the redox ability and high temperature thermal stability of cerium zirconium solid solution is still a challenge.In this paper,the cerium zirconium solid solution was prepared by a coprecipitation-hydrothermal method,and the effects of the ammonia concentration on their structures and redox properties were investigated.The results show that when the ammonia concentration is 0.8 mol/L,the aged sample(1100℃/10 h)of cerium zirconium solid solution has the highest specific surface area of 23.01 m^(2)/g.Additionally,the increase of ammonia concentration improves the uniformity of phase compositions and increases the oxygen vacancies.When the ammonia concentration reaches 0.4 mol/L,the cerium zirconium solid solution exhibits the best redox activity,with the lowest reduction temperature of 565℃.Therefore,increasing ammonia concentration in the hydrothermal treatment is beneficial to the thermal stability and redox performance of cerium zirconium solid solution.

Simultaneous recovery of rare earth elements and phosphorus from phosphate rock by phosphoric acid leaching and selective precipitation:Towards green process

Phosphate rock has been considered as one of the potential promising resources for rare earth elements(REEs). But the cost issues and the technical challenges caused by the low content of REEs in ores did hinder the further development of REEs recovery technologies. In order to explore a green process for the recovery of REEs from phosphate rock, this study investigates the effects of phosphoric acid concentration, liquid-to-solid ratio(L/S ratio), leaching time and temperature on the leaching efficiencies of the major components from phosphate rock. A REEs recovery of 94.3% and a phosphorus recovery of 95.3%are achieved under the optimal conditions of attacking phosphate rock using 30%P_2 O_5 acid with an L/S ratio of 10:1 and a stirring speed of 250 r/min at 25 ℃ for 4 h. Then,the selective precipitation of REEs with 81.3% REEs recovery is realized by heating up the leaching solution from 25 to 90 ℃ and keeping for4 h. Thereafter, more than 95% phosphoric acid is recovered by H_2 SO_4 and high purity gypsum, more than95% CaSO_4(tested by XRF), is also produced at the same time. Ultimately, a green process that leaches phosphate rock with H_3 PO_4, selectively precipitates REEs from leaching solution by heating up, recovers H_3 PO_4 with H2 SO4 is proposed. Compared with REE recovery in traditional processes, this process owns the merits of simple operation, energy saving and minimum wastes.

Precipitation-dissolution behaviors of rare earth ions in H_3PO_4-Ca(H_2PO_4)_2 solutions

In order to achieve deeper understanding of rare earth elements(REEs) behaviors during phosphate rock processing with H_3PO_4. The solubility of REEs in Ca(H_2PO_4)_2-H_3PO_4 solutions with various concentrations of Ca(H_2PO_4)_2 at different temperatures were tested. The results demonstrate that REEs solubility decreases sharply with the increasing concentration of Ca(H_2PO_4)_2. Equations between [REE^(3+)] and [H^+],[H^+] and [Ca^(2+)] in Ca(H_2PO_4)_2-H_3PO_4 solutions were built based on the precipitation-dissolution equilibrium of rare earth phosphates and the ionization equilibrium of H_3PO_4. According to the equations, the decreasing mechanism of REEs solubility caused by elevated concentration of Ca(H_2PO_4)_2 was determined. The mechanism can be illustrated as that the elevated concentration of [H_2 PO_4^-] decreases the concentration of hydrogen ion by retarding the ionization process of H_3PO_4 and directly promotes the precipitation of rare earth phosphates. Furthermore, it can be easy deduced that similar effect would be caused by the other cation impurities(Fe^(3+), Al^(3+), etc.) on REEs solubility based on the mechanism. In addition, superimposed reduction effect on REEs solubility caused by the elevated concentration of Ca(H_2PO_4)_2 and the elevated temperature is found. This superimposed effect leads to a super low solubility of REEs in Ca(H_2PO_4)_2-H_3PO_4 solution. On the basis of the experimental study, outlooks and suggestions for further development of REEs recovery method are given.