Exploration of markers in oxidized rancidity walnut kernels based on lipidomics and volatolomics.

Walnut kernels are prone to oxidation and rancidity due to their rich lipid composition, but the existing evaluation indicators are not sensitive enough to promote their industrial development. This study aims to investigate the potential markers in oxidative rancidity walnut kernels using lipidomics and volatolomics. The results showed that the antioxidant capacity of walnut kernels significantly decreased after oxidation, with the decreasing of total phenolic content from 36276.34 mg GAE/kg to 31281.53 mg GAE/kg, the DPPH and ABTS free radical scavenging activity from 89.25% to 73.54%, and 61.69% to 43.73%, respectively. The activities of lipoxygenase (LOX) and lipase (LPS) increased by 6.08-fold and 0.33-fold, respectively. By combining volatolomics and chemometrics methods, it was found that significant differences existed in the content of hexanal, caproic acid, 1-pentanol, (E)-2-octenal, and 2-heptanenal before and after walnut kernel oxidation (VIP > 1). Based on the results of lipidomics, it can be concluded that the above five compounds can serve as characteristic markers for walnut kernel oxidative rancidity, mainly produced through glycerol phospholipid (GPL), glyceride, linoleic acid (LA), and α-linolenic acid (ALA) metabolism pathways. Possible mechanisms of lipid degradation in oxidized walnut kernels were also proposed, providing technical support for the storage, preservation, and high-value utilization of walnut kernels.

Exploring the oxidative rancidity mechanism and changes in volatile flavors of watermelon seed kernels based on lipidomics.

Watermelon seed kernels (WSK) are prone to oxidative rancidity, while their evaluation biomarkers and changes in volatile flavor are still unknown. The research tracked the changes in volatile compounds and lipid components before and after rancidity using HS-SPME-GC-O-MS and lipidomic techniques. The results showed the flavor of watermelon seed kernels changed significantly before and after rancidity, from mild aroma to rancidity. A total of 42 volatile compounds were detected via GC-O-MS, and a total of 220 lipid molecules were detected via lipidomic technology. 55 lipids with significant differences were screened via multivariate statistical analysis. Combining the above analysis, it found that glycerol phospholipid and glyceride pathways were the most important metabolic pathways and 1-Pentanol and styrene could be used as potential biomarkers to judge the rancidity process of watermelon seed kernels. The research could provide powerful technical support for the storage, transportation and freshness preservation of watermelon seed kernels.

Walnut Protein Isolate-κ-Carrageenan Composite Gels Improved with Synergetic Ultrasound-Transglutaminase: Gelation Properties and Structure.

Walnut protein is a kind of natural, high-quality plant protein resource. However, its high content of gluten, strong hydrophobicity and poor gelation ability have greatly limited its development and utilization in gel products. It was found in this experiment that ultrasonic power combined with transglutaminase (TGase) had a significant effect on the gel properties of the walnut protein isolate (WNPI)-κ-carrageenan (KC) complex. The results showed that the gel strength of the WNPI-KC complex first increased and then decreased with the increase in ultrasonic power (0-400 W). WNPI-KC composite gel had the best texture properties, rheological properties, water-holding capacity (99.41 ± 0.76%), swelling ratio (2.31 ± 0.29%) and thermal stability (83.22 °C) following 200 W ultrasonic pretreatment. At this time, the gel network was more uniform and much denser, and the water molecules were more tightly bound. Further, 200 W ultrasonic pretreatment could promote the transformation of α-helices to ß-folds in protein molecules, improve the fluorescence intensity, increase the content of free sulfhydryl groups and enhance the intermolecular forces. The experimental results could provide technical support for the development of walnut protein gel food.

Effect of NaCl on the Rheological, Structural, and Gelling Properties of Walnut Protein Isolate-κ-Carrageenan Composite Gels.

In this study, we discovered that a certain concentration of Na+ (15 mM) significantly improved the bond strength (12.94 ± 0.93 MPa), thermal stability (72.68 °C), rheological properties, and textural attributes of walnut protein isolate (WNPI)-κ-carrageenan (KC) composite gel. Electrostatic force, hydrophobic interaction, hydrogen bond, and disulfide bond were also significantly strengthened; the α-helix decreased, and the ß-sheet increased in the secondary structure, indicating that the protein molecules in the gel system aggregated in an orderly manner, which led to a much denser and more uniform gel network as well as improved water-holding capacity. In this experimental research, we developed a new type of walnut protein gel that could provide technical support for the high-value utilization and quality control of walnut protein.

Physicochemical, structural and adhesion properties of walnut protein isolate-xanthan gum composite adhesives using walnut protein modified by ethanol.

Low-sugar and high-protein adhesives have broad market application prospects, while natural plant proteins have confronted technical bottlenecks due to their poor adhesion. In this study, the effects of ethanol with different concentrations (0-80%) on the adhesion properties of walnut protein isolate-xanthan gum (WNPI-XG) composite adhesives were investigated. Results showed the bonding strength of WNPI-XG treated with 40% ethanol reached 12.55 MPa, the denaturation temperature and the surface hydrophobicity increased to 87.91 and 185.07 respectively, displaying the best rheological and texture properties. It also indicated appropriate concentration of ethanol (40%) didn't change the molecular weight of WNPI-XG, but greatly strengthened the fluorescence intensity, leading changes in contents of reactive sulfhydryl groups, electrostatic forces, hydrophobic interactions, hydrogen bonds and disulfide bonds. Furthermore, the treatment also facilitated a conformation conversion of the secondary structures from ß-sheet to α-helix, promoting the full unfolding of protein molecules. The microstructure analysis showed after 40% ethanol treatment, the WNPI structure was uniform, the surface of WNPI-XG adhesive was flat and smooth, combined more closely with water molecules. By analyzing the influence of ethanol treatment on adhesion of WNPI-XG, the research laid a theoretical foundation for protein modification, providing good technical references for its development and utilization.

Study on the emulsification and oxidative stability of ovalbumin-pectin-pumpkin seed oil emulsions using ovalbumin solution prepared by ultrasound.

Pumpkin seed oil (PSO), which is a valuable compound with high nutritional value used for the prevention of various chronic diseases, is prone to oxidation. In this work, small and uniform (su) ovalbumin (OVA) and pectin (PEC) were used to stabilize PSO in the form of an emulsion. The results showed that suOVA-PEC-PSO emulsion with a droplet size of 9.82 ± 0.05 µm was successfully self-assembled from PSO, PEC, and suOVA solution (with a droplet size of 230.13 ± 14.10 nm) treated with 300 W ultrasound, owing to the formation of a more stable interfacial film on the surface of droplets. The interfacial, rheological, emulsifying, and antioxidant properties of the suOVA-PES-PSO emulsions were excellent, owing to the synergistic effects between PEC and suOVA solution. Moreover, the physical stability of the suOVA-PEC-PSO emulsions to salt stress, a freeze-thaw cycle, and heat treatment was also increased and the oxidation of linolenic acid was notably delayed. These results have extended the food-related applications of OVA and PSO, and provide a promising foundation for further exploration of the self-assembly of composite emulsions by small and uniform proteins.

Effects of irradiation treatment on protein structure and digestion characteristics of seed-watermelon (Citrullus lanatus var.) kernel protein.

This study examined the effects of different doses of irradiation treatments on protein structure and digestion characteristic of seed-watermelon seed kernel protein. The results showed that, the molecular structure of seed-watermelon kernel protein was unfolded after the irradiation treatment, the content of ß-sheet structure in the secondary structure was decreased, while the content of random coil structure increased. The average particle size of the protein increased, and the hydrophobic group buried in the ß-sheet structure was exposed hence the surface hydrophobicity increased. Besides, the surface morphology of seed-watermelon protein changed from smooth and flat to coarse and concave, the specific surface area in contact with the aqueous medium increased and its solubility increased, the distribution of peptides in the digesta became wider, and the small molecular weight peptides gradually increased.

Study on the Emulsifying Properties of Pomegranate Peel Pectin from Different Cultivation Areas.

Pomegranate peel pectin is an important acidic anionic plant polysaccharide which can be used as a natural emulsifier. In order to study its emulsifying properties, this paper systematically analyses pomegranate peel pectin samples from Chinese Xinjiang, Sichuan and Yunnan provinces, through rheometer, interfacial rheometer, Zetasizer Nano-ZS and mastersizer. It is shown that pomegranate peel pectin can effectively reduce the oil-water interfacial tension, reaching an emulsion droplet size of only 0.507 µm, 0.669 µm and 0.569 µm, respectively, while the pectin concentration is 1.5% and the oil phase (MCT) is 10%. It has also shown that the extreme conditions of pH and ion strength can not significantly change its emulsion stability. However, freeze-thaw cycles can cause the pomegranate peel pectin emulsion to become less stable. Furthermore, the effects of decolourization, protein removal and dialysis on the emulsifying properties of pomegranate peel pectin are investigated using mastersizer rheometer and interfacial rheometer. It is found that the protein and pigment in pomegranate peel pectin have little effect on its emulsifying properties, while the results from dialyzed pectin show that the small molecule substances can reduce the emulsion particle size and increase the emulsion stability. The research outcomes of this study provide technical support for the further application of pomegranate peel pectin in the food industry.

Effect of SGLT2 inhibitor on renal function in patients with type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: This study summarizes the evidence from randomized controlled trials (RCTs) to assess the effects of SGLT2 inhibitors on renal function and albuminuria in patients with type 2 diabetes. MATERIALS/METHODS: We searched PubMed, Web of Science, Cochrane Library and EMBASE for reports published up to March 2018 and included RCTs reporting estimated glomerular filtration rate (eGFR) and/or urine albumin/creatinine ratio (UACR) changes. Data extraction and assessment of research quality based on Cochrane risk biasing tools. Data were calculated to represent the standardized mean difference (SMD) for each study, and the SMDs with 95% confidence intervals (CIs) were pooled using a random effects model. RESULTS: Fifty-one studies were included that evaluated eGFR levels, and 17 studies were included that evaluated UACR levels. A meta-analysis showed that SGLT2 inhibitors had no significant effect on eGFR levels (SMD - 0.02, 95% CI - 0.06, 0.03, p = 0.45), and eGFR reduction was observed in the subsets of the duration of the trial 12 < duration ≤ 26 weeks (SMD - 0.08, 95% CI - 0.13, - 0.02, p = 0.005) and mean baseline eGFR < 60 ml/min per 1.73 square meters (SMD - 0.22, 95% CI - 0.37, - 0.07, p = 0.004). We found that SGLT2 inhibitors reduced UACR levels in patients with type 2 diabetes (SMD - 0.11, 95% CI - 0.17, - 0.05, p = 0.0001). Compared with monotherapy, the combination with other hypoglycemic agents can reduce albuminuria levels (SMD - 0.13, 95% CI - 0.19, - 0.06, p < 0.0001). CONCLUSIONS: The effect of SGLT2 inhibitor on eGFR in patients with T2DM was not statistically significant, but it was effective in reducing albuminuria levels.

Upregulation of Heme Oxygenase-1 by Hemin Alleviates Sepsis-Induced Muscle Wasting in Mice.

Hemin, an inducer of heme oxygenase-1 (HO-1), can enhance the activation of HO-1. HO-1 exhibits a variety of activities, such as anti-inflammatory, antioxidative, and antiapoptotic functions. The objective of this study was to investigate the effects of hemin on sepsis-induced skeletal muscle wasting and to explore the mechanisms by which hemin exerts its effects. Cecal ligation and perforation (CLP) was performed to create a sepsis mouse model. Mice were randomly divided into four groups: control, CLP, CLP plus group, and CLP-hemin-ZnPP (a HO-1 inhibitor). The weight of the solei from the mice was measured, and histopathology was examined. Cytokines were measured by enzyme-linked immunosorbent assay (ELISA). Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blotting were used to assess the expression levels of HO-1 and atrogin-1. Furthermore, we investigated the antioxidative effects of HO-1 by detecting malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity. CLP led to dramatic skeletal muscle weakness and atrophy, but pretreatment with hemin protected mice against CLP-mediated muscle atrophy. Hemin also induced high HO-1 expression, which resulted in suppressed proinflammatory cytokine and reactive oxygen species (ROS) production. The expression of MuRF1 and atrogin-1, two ubiquitin ligases of the ubiquitin-proteasome system- (UPS-) mediated proteolysis, was also inhibited by increased HO-1 levels. Hemin-mediated increases in HO-1 expression exert protective effects on sepsis-induced skeletal muscle atrophy at least partly by inhibiting the expression of proinflammatory cytokines, UPS-mediated proteolysis, and ROS activation. Therefore, hemin might be a new treatment target against sepsis-induced skeletal muscle atrophy.

Endogenously synthesized n-3 fatty acids in fat-1 transgenic mice prevent melanoma progression by increasing E-cadherin expression and inhibiting ß-catenin signaling.

Malignant melanoma is the most lethal form of skin cancer. Although preclinical studies have shown that n-3 polyunsaturated fatty acids (PUFAs) are beneficial for prevention of melanoma, the molecular mechanisms underlying the protective effects of n­3 PUFAs on melanoma remain largely unknown. In the present study, endogenously increased levels of n-3 PUFAs in the tumor tissues of omega­3 fatty acid desaturase (fat­1) transgenic mice was associated with a reduction in the growth rate of melanoma xenografts. This reduction in tumor growth in fat­1 mice compared with wild­type controls may have been associated, in part, to the: i) Increased expression of E­cadherin and the reduced expression of its transcriptional repressors, the zinc finger E­box binding homeobox 1 and snail family transcriptional repressor 1; ii) significant repression of the epidermal growth factor receptor/Akt/ß­catenin signaling pathway; and iii) formation of significant levels of n­3 PUFA­derived lipid mediators, particularly resolvin D2 and E1, maresin 1 and 15­hydroxyeicosapentaenoic acid. In addition, vitamin E administration counteracted n­3 PUFA­induced lipid peroxidation and enhanced the antitumor effect of n­3 PUFAs, which suggests that the protective role of n­3 PUFAs against melanoma is not mediated by n­3 PUFAs­induced lipid peroxidation. These results highlight a potential role of n­3 PUFAs supplementation for the chemoprevention of melanoma in high­risk individuals, and as a putative adjuvant agent in the treatment of malignant melanoma.

[High glucose dialysate enhances peritoneal fibrosis through upregulating glucose transporters GLUT1 and SGLT1].

Objective: To investigate the role of glucose transporter 1 (GLUT1) and sodium-glucose cotransporter 1 (SGLT1) in high glucose dialysate-induced peritoneal fibrosis. Methods: Thirty six male SD rats were randomly divided into 6 groups (6 in each):normal control group, sham operation group, peritoneal dialysis group (PD group), PD+phloretin group (PD+T group), PD+phlorizin group (PD+Z group), PD+phloretin+phlorizin group (PD+T+Z group). Rat model of uraemia was established using 5/6 nephrotomy, and 2.5% dextrose peritoneal dialysis solution was used in peritoneal dialysis. Peritoneal equilibration test was performed 24 h after dialysis to evaluate transport function of peritoneum in rats; HE staining was used to observe the morphology of peritoneal tissue; and immunohistochemistry was used to detect the expression of GLUT1, SGLT1, TGF-ß1 and connective tissue growth factor (CTGF) in peritoneum. Human peritoneal microvascular endothelial cells (HPECs) were divided into 5 groups:normal control group, peritoneal dialysis group (PD group), PD+phloretin group (PD+T group), PD+phlorezin group (PD+Z group), and PD+phloretin+phlorezin group (PD+T+Z group). Real time PCR and Western blotting were used to detect mRNA and protein expressions of GLUT1, SGLT1, TGF-ß1, CTGF in peritoneal membrane and HPECs. Results:In vivo, compared with sham operation group, rats in PD group had thickened peritoneum, higher ultrafiltration volume, and the mRNA and protein expressions of GLUT1, SGLT1, CTGF, TGF-ß1 were significantly increased (all P<0.05); compared with PD group, thickened peritoneum was attenuated, and the mRNA and protein expressions of GLUT1, SGLT1, CTGF, TGF-ß1 were significantly decreased in PD+T, PD+Z and PD+T+Z groups (all P<0.05). Pearson's correlation analysis showed that the expressions of GLUT1, SGLT1 in peritoneum were positively correlated with the expressions of TGF-ß1 and CTGF (all P<0.05). In vitro, the mRNA and protein expressions of GLUT1, SGLT1, TGF-ß1, CTGF were significantly increased in HPECs of peritoneal dialysis group (all P<0.05), and those in PD+T, PD+Z, and PD+T+Z groups were decreased (all P<0.05). Pearson's correlation analysis showed that the expressions of GLUT1, SGLT1 in HPECs were positively correlated with the expressions of TGF-ß1 and CTGF (all P<0.05). Conclusion: High glucose peritoneal dialysis fluid may promote peritoneal fibrosis by upregulating the expressions of GLUT1 and SGLT1.

Salidroside rescued mice from experimental sepsis through anti-inflammatory and anti-apoptosis effects.

BACKGROUND: Salidroside (SDS) is the main effective component of Rhodiola rosea L with a variety of pharmacologic properties. The objective of this study was to investigate the efficacy of SDS in the treatment of experimental sepsis in mice and explore the possible underlying action mechanisms. METHODS: Sepsis was induced in C57BL/6 male mice via cecal ligation and puncture (CLP). The animals were divided into three groups as follows: sham, CLP, and CLP plus SDS. SDS (50 mg/kg) was injected intraperitoneally 1 h after operation. Postoperative survival of the mice, bacterial clearance in blood and peritoneal lavage fluid, cytokine secretion in blood, and histology of lung were evaluated. In addition, apoptosis of immune cells in the spleen and thymus were examined, respectively. RESULTS: SDS administration prolonged the survival of the septic mice, inhibited the proinflammatory responses, and enhanced bacterial clearance. It also alleviated the pathologic changes in the lung and inhibited the apoptosis of immune cells in the spleen and thymus after CLP challenge. CONCLUSIONS: SDS exerts a protective effect in CLP-induced sepsis by attenuating the proinflammatory responses, enhancing bacterial clearance, and preserving adaptive immunity. SDS may be a promising therapeutic strategy for the treatment of sepsis.

The size of endotracheal tube and sore throat after surgery: a systematic review and meta-analysis.

BACKGROUND: Recent studies showed that sore throat following endotracheal intubation was a common problem following surgery. The objective of this systematic review and meta-analysis of published randomized controlled trials (RCTs) or cohort studies was to estimate whether the size of endotracheal tube (ETT) affects the incidence of postoperative sore throat (POST) after general anesthesia. METHODS: The following databases were searched electronically: PubMed (updated to Dec 2012), EMBASE (updated to 15 Dec 2012), Google scholar, World Health Organization International Clinical Trials Registry Platform (Jul 2011), Chinese BioMedical Literature Database (1978 to Jul 2011), and China National Knowledge Infrastructure (1994 to Jul 2011). Studies comparing the size of endotracheal tube for elective surgery were included. RESULTS: Three trials with a total of 509 female patients were included in the current analysis. The size of ETT used were 6.0 mm and 7.0 mm. Pooled studies from these trials showed that the smaller size of ETT (6.0 mm) significantly decreased the incidence of POST in post-anesthesia care unit (PACU) (RR = 0.56, 95% CI 0.42-0.75, P<0.01) and at 24 h after surgery (RR = 0.69, 95% CI 0.48-0.99, P<0.05). A smaller size of ETT (6.0 mm) was associated with a lower incidence of PH in PACU (RR = 0.69, 95% CI 0.55-0.87, P<0.01), but did not affect the incidence of PH at 24 h after surgery (RR = 0.73, 95% CI 0.46-1.15, P>0.05). CONCLUSION: Our meta-analysis suggests that patients under general anesthesia with a smaller size of ETT (6.0 mm) were associated with a lower incidence of POST in female patients. More studies with adequate numbers of patients were warranted to evaluate other size of ETT on the incidence of PH and POST after general surgery among different populations.