Purification and identification of xanthine oxidase inhibitory peptides from enzymatic hydrolysate of α-lactalbumin and bovine colostrum casein

The development of food-derived Xanthine Oxidase (XO) inhibitors is critical to the treatment of hyperuricemia and oxidative stress-related disease. Few studies report on milk protein hydrolysates' XO inhibitory activity, with the mechanism of their interaction remaining elusive. Here, different commercial enzymes were used to hydrolyze α-lactalbumin and bovine colostrum casein. The two proteins hydrolyzed by alkaline protease exhibited the most potent XO inhibitory activity (bovine casein: IC₅₀ = 0.13 mg mL^-1; α-lactalbumin: IC₅₀ = 0.28 mg mL^-1). Eight potential XO inhibitory peptides including VYPFPGPI, GPVRGPFPIIV, VYPFPGPIPN, VYPFPGPIHN, QLKRFSFRSFIWR, LVYPFPGPIHN, AVFPSIVGR, and GFININSLR (IC₅₀ of 4.67-8.02 mM) were purified and identified from alkaline protease hydrolysates by using gel filtration, LC-MS/MS and PeptideRanker. The most important role of inhibiting activity of peptides is linked to hydrophobic interactions and hydrogen bonding based on the results of molecular docking and molecular dynamics simulation. The enzymatic hydrolysate of α-lactalbumin and bovine colostrum casein could be a competitive candidates for hyperuricemia-resisting functional food.

[Effects of Straw Returning and Biochar Application on Summer Maize Yield and Soil N2O Emission in Guanzhong Plain]

Here, we investigated the effects of straw returning combined with biochar application on summer maize yield and soil nitrous oxide (N₂O) emissions, based on a field location trial in the Guanzhong Plain from 2019 to 2020. The soil N₂O emission rates were monitored using the static chamber-chromatography method. A comprehensive analysis of summer maize yields, soil N₂O emissions, and soil labile nitrogen components was conducted to clarify the effects of straw returning combined with biochar application on improving soil fertility, increasing summer maize yield, and reducing greenhouse gas emissions. The three treatments were no straw returning (S₀), straw returning (S), and straw returning combined with biochar application (SB). The results showed that the peak of N₂O emissions from each treatment occurred 10 d after the straw return, and the rate of soil N₂O emissions remained at a low level after 30 d of straw return. The rate of soil N₂O emissions showed highly significant positive correlations (P<0.05) with ammonium nitrogen (NH₄⁺-N), inorganic nitrogen (SIN), microbial nitrogen (MBN), and dissolved organic nitrogen (DON) contents. S significantly increased summer maize yield, cumulative N₂O emissions, yield-scaled N₂O intensity, and total nitrogen (TN) content by 7.4%-13%, 65.8%-132.2%, 54.6%-103%, and 27.8%-33%, respectively, compared to those in S₀. Although the trend for SB to increase summer maize yield (2.5%-3.3%) compared to that in S was not significant (P>0.05), SB significantly reduced cumulative N₂O emissions and yield-scaled N₂O intensity by 24.0%-27.3% and 26.4%-29.2%, respectively, compared to that in S. SB significantly reduced the rate of soil N₂O emissions by 45.1%-69.6% at the peak of N₂O emissions compared to that in S. Biochar application mitigated soil N₂O emissions induced by straw return and had a peak-shaving effect. SB significantly increased soil total N by 9.1%-12.2% compared to that in S. Combining summer maize yield, soil N₂O emissions, and TN content, SB not only improved soil fertility and summer maize yield but also reduced yield-scaled N₂O intensity, making it a suitable management practice that can be replicated to balance crop yield and environmental friendliness.

Acetazolamide Alleviate Cerebral Edema Induced by Ischemic Stroke Through Inhibiting the Expression of AQP4 mRNA

OBJECTIVE

We want to investigate the effect of aquaporin-4 (AQP4) on cerebral edema induced by ischemic stroke in rats and explore whether inhibiting the expression of AQP4 through acetazolamide (AZA) could attenuate brain edema and protect cerebral function.

METHODS

The Sprague Dawley (SD) rats were randomly divided into four groups: sham + saline group, sham + AZA group, AZA intervention group, and nonintervention group. Each group was divided into five subgroups according to the time of cerebral ischemia (6 h, 1 day, 3 days, 5 days, and 7 days). The model of cerebral infarction in rats was adopted by means of the bilateral carotid arteries ligation (2-VO) method. The rats in intervention group were given intraperitoneal injection of AZA (35 mg/kg/day). Hematoxylin-eosin staining was performed for pathological analysis of the infarcted area. The brain water content was calculated to evaluate the degree of brain edema. The messenger RNA (mRNA) and protein expressions of AQP4 in the brain were measured by quantitative real-time polymerase chain reaction and immunohistochemistry, respectively.

RESULTS

Significant cerebral pathological damages were found in ischemic stroke rats. The brain water content, protein, and mRNA expression of AQP4 of the intervention and nonintervention groups were markedly higher than those of the sham groups. By contrast, AZA administration reduced the brain water content, whereas improved cerebral dysfunction was induced by ischemic stroke. Moreover, AZA obviously reduced the protein and mRNA expression of AQP4 after ischemic stroke in rats' brains.

CONCLUSIONS

The expression of AQP4 was closely related to cerebral edema induced by ischemic stroke. Decreasing the expression of AQP4 mRNA by AZA administration can effectively relieve cerebral edema and decrease cerebral pathological damage.

Icariin ameliorates streptozocin-induced diabetic nephropathy through suppressing the TLR4/NF-κB signal pathway

Diabetic nephropathy (DN) is one of the complex and severe complications of diabetes mellitus (DM). Icariin (ICA) is a flavonoid extracted from the leaves and stems of Herba epimedii with a wide range of pharmacological effects, such as anti-osteoporosis, anti-fibrosis, anti-aging, anti-inflammation and antioxidation. The purpose of our study was to explore the renal protective effect of ICA on DN in mice and its possible mechanisms. ICR mice were exposed to STZ-induced DN. The kidney organ coefficient of mice was computed. 24 h UP in urine was measured. Serum FBG, Cr and BUN were detected. The content of MDA and the activities of SOD, CAT and GSH-Px in renal tissues were tested. HE staining, PAS staining, PASM staining and transmission electron microscopy were used to observe renal pathological changes. Furthermore, TLR4, p-NF-κB p65, TNF-α and IL-6 of renal tissues were assayed by immunohistochemistry and western blotting. Our results indicated that ICA observably optimized the renal organ coefficient, reduced the level of 24 h UP in urine, decreased the content of Cr, BUN in serum and MDA in renal tissues, promoted the activities of SOD, CAT and GSH-Px in renal tissues, and ameliorated pathological lesions of kidneys noticeably. Besides, ICA inhibited the expressions of TLR4, p-NF-κB p65, TNF-α and IL-6 remarkably in renal tissues. ICA, which might lighten the renal inflammatory response by suppressing the TLR4/NF-κB signal pathway, played a protective role in kidneys of STZ-induced DN mice.

[Effects of Nitrogen Fertilizer and Straw Returning Methods on N2O Emissions in Wheat-Maize Rotational Soils]

In order to explore the impacts of nitrogen fertilizer and straw returning methods on N₂O emissions, a two-factor split-zone design was adopted for experimentation under the winter wheat-summer maize rotation model in the Guanzhong area of Shanxi, China. The main areas of interest were conventional nitrogen (G) and reduced nitrogen (70% G); the sub-areas were straw no return (N), straw return (S), and straw return + biochar (SB); we analyzed their impacts on N₂O emissions and crop yield, and the relationships with related impact factors. The results showed that the N₂O emissions peaks appeared in the wheat season and maize season treatments within 5-16 days after fertilization, and also appeared after rainfall. The N₂O flux was significantly and positively correlated with soil temperature and NH₄⁺-N content. Regardless of the wheat season, maize season, or annual total N₂O emissions, the 70% GSB treatment was the lowest and the GS treatment was the highest. At the same level of nitrogen application, S treatment increased N₂O emissions, SB treatment could reduce N₂O emissions, both S and SB treatments could significantly increase crop yields, and SB production increased more; 70%G-level annual N₂O emissions, when compared with the G level, had been reduced by 40% to 48%, while the yield has not decreased significantly. Through comprehensive consideration, a reduction of nitrogen by 30% was achieved through the combination of straw + biochar on the basis of conventional nitrogen application, while ensuring high crop yields and the best N₂O emissions reduction.

The significance of Siglec-15 expression in resectable non-small cell lung cancer

Siglec-15 (S15) is another important mechanism of tumor immune escape besides the PD-L1/PD-1 pathway and represents a new kind of immune checkpoint inhibitor. However, the associations of tumor Siglec-15 expression with clinicopathological characteristics and outcomes of non-small cell lung cancer (NSCLC), and tumor-infiltrating lymphocytes (TILs) in a tumor microenvironment (TME) have so far been unclear. A total of 324 NSCLC surgical samples on tumor microarray were used in this study for investigating the association of S15 expression with clinicopathological characteristics and overall survival (OS) as well as correlation with TILs using multiplex immunofluorescence staining and PD-L1. Results showed that the expression of S15 in adenocarcinoma was significantly higher than that in squamous cell carcinoma. S15 expression was positively correlated with CD8+ T cell density in the stroma. The expression rate of PD-L1 in lung squamous cell carcinoma was higher than that in lung adenocarcinoma. S15 expression was not associated with the prognosis of early NSCLC. The pathological mechanism of the co-expression of S15 and PD-L1 in resectable NSCLC remains to be further studied.

Selecting the optimum conditions for two-dimensional difference gel electrophoresis of proteins expressed in Populus euphratica

We selected the optimum conditions for two-dimensional difference gel electrophoresis (2D-DIGE) of proteins expressed in the heteromorphic leaves of Populus euphratica Oliv. by adjusting the isoelectric focusing, the loading quantity, the concentration of the electrophoretic gel, and other parameters. The results of our study showed that protein separation was improved with many clear protein spots observed, and the differentiations were obvious. The findings of this study will be useful for future studies of protein expression in the heteromorphic leaves of P. euphratica.

Long-term outcomes after radical gastrectomy in gastric cancer patients with overt bleeding

AIM: To investigate the difference in long-term outcomes between gastric cancer patients with and without a primary symptom of overt bleeding (OB).

METHODS: Consecutive patients between January 1, 2007 and March 1, 2012 were identified retrospectively by reviewing a gastric cancer database at Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine. A follow-up examination was performed on patients who underwent a radical gastrectomy. OB due to gastric cancer included hematemesis, melena or hematochezia, and gastric cancer was confirmed as the source of bleeding by endoscopy. Patients without OB were defined as cases with occult bleeding and those with other initial presentations, including epigastric pain, weakness, weight loss and obstruction. The 3-year overall survival (OS) rate, age, gender, AJCC T stage, AJCC N stage, overall AJCC stage, tumor size, histological type, macroscopic (Borrmann) type, lymphovascular invasion and R status were compared between patients with and without OB. Moreover, we carried out a subgroup analysis based on tumor location (upper, middle and lower).

RESULTS: We identified 939 patients. Of these, 695 (74.0%) were hospitalized for potential radical gastrectomy and another 244 received palliative resection, rerouting of the gastrointestinal tract, chemotherapy, radiotherapy or no treatment due to the presence of unresectable tumors. Notably, there was no significant difference in the percentage of OB patients between resectable cases and unresectable cases (20.3% vs 22.1%, P = 0.541). Follow-up examination was performed on 653 patients (94%) who underwent radical gastrectomy. We found no significant difference in 3-year OS rate (68.2% vs 61.2%, P = 0.143) or clinicopathological characteristics (P > 0.05) between these patients with and without OB. Subgroup analysis based on tumor location showed that the 3-year OS rate of upper gastric cancer was significantly higher in patients with OB (84.6%) than in those without OB (48.1%, P < 0.01) and that AJCC stages I-II (56.4% vs 35.1%, P = 0.017) and T1-T2 category tumors (30.8% vs 13%, P = 0.010) were more frequent in patients with OB than in those without OB. There was no significant difference in 3-year OS rate or clinicopathological characteristics between patients with and without OB (P > 0.05) for middle or lower gastric cancer.

CONCLUSION: Upper gastric cancer patients with OB exhibited tumors at less advanced pathological stages and had a better prognosis than upper gastric cancer patients without OB.