The effect of protein oxidation on the formation of advanced glycation end products after chicken myofibrillar protein glycation

Investigation that protein oxidation to the formation of advanced glycation end products(AGEs)after chicken myofibrillar protein glycation is limited.Models of protein oxidation induced by different concentrations of hydroxyl radicals(·OH)were developed after the chicken myofibrillar protein mild glycation(MPG).Results exhibited that levels of AGEs and surface hydrophobicity(H_(0))steadily increased with the a ddition of h ydrogen peroxide(H_(2)O_(2))concentration.However,levels of s ulfhydryl group,free amino group,and particle size gradually decreased with the H_(2)O_(2)concentration.The protein carbonyl value increased in H_(2)O_(2)concentration until 10 mmol/L.Pearson's correlation indicated that MPG structure modification(unfolding and degradation)induced by protein oxidation were significantly positively correlated with AGEs concentration(P<0.05).Finally,a mechanism was proposed to hypothesize t he effect of protein oxidation on the formation of AGEs under MPG conditions.

Metformin promotes angiogenesis and functional recovery in aged mice after spinal cord injury by adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway

Treatment with metformin can lead to the recovery of pleiotropic biological activities after spinal cord injury.However,its effect on spinal cord injury in aged mice remains unclear.Considering the essential role of angiogenesis during the regeneration process,we hypothesized that metformin activates the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway in endothelial cells,thereby promoting microvascular regeneration in aged mice after spinal cord injury.In this study,we established young and aged mouse models of contusive spinal cord injury using a modified Allen method.We found that aging hindered the recovery of neurological function and the formation of blood vessels in the spinal cord.Treatment with metformin promoted spinal cord microvascular endothelial cell migration and blood vessel formation in vitro.Furthermore,intraperitoneal injection of metformin in an in vivo model promoted endothelial cell proliferation and increased the density of new blood vessels in the spinal cord,thereby improving neurological function.The role of metformin was reversed by compound C,an adenosine monophosphate-activated protein kinase inhibitor,both in vivo and in vitro,suggesting that the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway likely regulates metformin-mediated angiogenesis after spinal cord injury.These findings suggest that metformin promotes vascular regeneration in the injured spinal cord by activating the adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway,thereby improving the neurological function of aged mice after spinal cord injury.

Changes of protein oxidation,lipid oxidation and lipolysis in Chinese dry sausage with different sodium chloride curing salt content

The effect of sodium chloride(NaCl)curing salt content on protein oxidation,lipid oxidation and lipolysis of Chinese dry sausage was investigated.Two groups Chinese dry sausages with 2%and 4%(m/m)salt content were studied.The degree of protein oxidation increased during the processes in two groups sausages,while the content of phospholipids decreased,neutral lipids and free fatty acids increased.The degree of protein oxidation,lipid oxidation and lipolysis in 4%NaCl content group was higher than those in 2%NaCl content group,while 4%NaCl content group has higher lipase activity.In conclusion,4%NaCl may facilitate the protein oxidation,lipid hydrolysis and oxidation in Chinese dry sausage,and the protein oxidation had strong correlation with lipid oxidation and lipolysis.The results could provide a basis for improving the technology of industrial production.

Neuroprotective mechanisms of rutin for spinal cord injury through anti-oxidation and anti-inflammation and inhibition of p38 mitogen activated protein kinase pathway

Rutin has anti-inflammatory, antioxidant, anti-viral, anti-tumor and immune regulatory effects. However, the neuroprotective effects of rutin in spinal cord injury are unknown. The p38 mitogen activated protein kinase （p38 MAPK） pathway is the most important member of the MAPK family that controls inflammation. We assumed that the mechanism of rutin in the repair of spinal cord injury is associated with the inhibition of p38 MAPK pathway. Allen’s method was used to establish a rat model of spinal cord injury. The rat model was intraperitoneally injected with rutin （30 mg/kg） for 3 days. After treatment with rutin, Basso, Beattie and Bresnahan locomotor function scores increased. Water content, tumor necrosis factor alpha, interleukin 1 beta, and interleukin 6 levels, p38 MAPK protein expression and caspase-3 and -9 activities in T8–9 spinal cord decreased. Oxidative stress related markers superoxide dismutase and glutathione peroxidase levels increased in peripheral blood. Rutin exerts neuroprotective effect through anti-oxidation, anti-inflammation, anti-apoptosis and inhibition of p38 MAPK pathway.

The pathogenic mechanism of TAR DNA-binding protein 43(TDP-43)in amyotrophic lateral sclerosis

The onset of amyotrophic lateral sclerosis is usually characterized by focal death of both upper and/or lower motor neurons occurring in the motor cortex,basal ganglia,brainstem,and spinal cord,and commonly involves the muscles of the upper and/or lower extremities,and the muscles of the bulbar and/or respiratory regions.However,as the disease progresses,it affects the adjacent body regions,leading to generalized muscle weakness,occasionally along with memory,cognitive,behavioral,and language impairments;respiratory dysfunction occurs at the final stage of the disease.The disease has a complicated pathophysiology and currently,only riluzole,edaravone,and phenylbutyrate/taurursodiol are licensed to treat amyotrophic lateral sclerosis in many industrialized countries.The TAR DNA-binding protein 43 inclusions are observed in 97%of those diagnosed with amyotrophic lateral sclerosis.This review provides a preliminary overview of the potential effects of TAR DNAbinding protein 43 in the pathogenesis of amyotrophic lateral sclerosis,including the abnormalities in nucleoplasmic transport,RNA function,post-translational modification,liquid-liquid phase separation,stress granules,mitochondrial dysfunction,oxidative stress,axonal transport,protein quality control system,and non-cellular autonomous functions(e.g.,glial cell functions and prion-like propagation).

Biochanin A attenuates spinal cord injury in rats during early stages by inhibiting oxidative stress and inflammasome activation

Previous studies have shown that Biochanin A,a flavonoid compound with estrogenic effects,can serve as a neuroprotective agent in the context of cerebral ischemia/reperfusion injury;howeve r,its effect on spinal cord injury is still unclea r. In this study,a rat model of spinal cord injury was established using the heavy o bject impact method,and the rats were then treated with Biochanin A(40 mg/kg) via intrape ritoneal injection for 14 consecutive days.The res ults showed that Biochanin A effectively alleviated spinal cord neuronal injury and spinal co rd tissue injury,reduced inflammation and oxidative stress in spinal cord neuro ns,and reduced apoptosis and pyroptosis.In addition,Biochanin A inhibited the expression of inflammasome-related proteins(ASC,NLRP3,and GSDMD)and the Toll-like receptor 4/nuclear factor-κB pathway,activated the Nrf2/heme oxygenase 1 signaling pathway,and increased the expression of the autophagy markers LC3 Ⅱ,Beclin-1,and P62.Moreove r,the therapeutic effects of Biochanin A on early post-s pinal cord injury were similar to those of methylprednisolone.These findings suggest that Biochanin A protected neurons in the injured spinal cord through the Toll-like receptor 4/nuclear factor κB and Nrf2/heme oxygenase 1 signaling pathways.These findings suggest that Biochanin A can alleviate post-spinal cord injury at an early stage.

Evaluation of the Protein Requirement in Chinese Young Adults Using the Indicator Amino Acid Oxidation Technique

Objective To accurately calculate the protein requirements in Chinese young adults using the indicator amino acid oxidation technique. Methods Nine women and ten men received a restricted daily level of protein intake （0.75, 0.82, 0.89, 0.97, and 1.05 g/kg）, along with L-[1-13C]-Ieucine. Subjects＇ protein requirement was determined by a biphasic linear regression crossover analysis of F13C02 data. In doing so, a breakpoint at the minimal rate of appearance of 13C02 expiration specific to each level of dietary protein was identified. This trial was registered with the Chinese clinical trial registry as ChiCTR-ONC-11001407. Results The Estimated Average Requirement （EAR） and the Recommended Nutrient Intake （RNI） of protein for healthy Chinese young adults were determined to be 0.87 and 0.98 g/（kg.d）, respectively, based on the indicator amino acid oxidation technique. Conclusion The EAR and RNI of mixed protein are 5% and 16% that are lower than the current proposed EAR and RNI {0.92 and 1.16 g/（kg.d）, respectively）, as determined by the nitrogen balance method. The respective EAR and RNI recommendations of 0.87 and 0.98 g/（kg.d） of mixed protein are estimated to be reasonable and suitable for Chinese young adults.

The Inhibiting Effect of Bone Protein Hydrolysates on Lipid Oxidation in Pork Patties

Bone protein hydrolysates were prepared by limited alcalase hydrolysis （5 h）. The hydrolysates were formulated （0-3%, w/w） into pork patties to determine the antioxidant efficacy. 0.02% BHA （butylated hydroxyanisole） was used as a positive control. Lipid oxidation in patties during storage was analyzed by measuring the TBARS and protein carbonyl content. The results showed that bone protein hydrolysates possessed significant antioxidant activity, and antioxidant activity increased with the increasing hydrolysates concentration. Sensory evaluation indicated that bone protein hydrolysates improved the color and decreased lipid oxidation flavor of pork patties. The 2% bone hydrolysates possessed the highest antioxidant activity and better sensory quality, and its effect was closed to 0.02% BHA.

Effect of AAPH oxidation on digestion characteristics of seed watermelon(Citrullus lanatus var)kernels protein isolates

Seed watermelon kernel is a typical complex food with high fat and protein contents.During storage and processing,it is often affected by various factors to undergo interactions between components,which lead to its quality change.In this experiment,seed watermelon kernels were used as research objects,and the effects of 2-Azobis(2-amidinopropane)dihydrochloride(AAPH)on seed watermelon kernel protein isolates(WMP)were investigated.The structure and digestion characteristics of WMP after oxidation were studied.The results showed that with the increase of AAPH concentration(0.05−5 mol/L),WMP showed obvious aggregation,and its solubility decreased from 6.76 mg/mL to 9.59 mg/mL.The free sulfhydryl content of WMP was 18.24 mmol/g decreased to 11.25 mmol/g,α-helix decreased andβ-sheet decreased in secondary structure,and its disulfide bond increased by 43.06 mmol/g from 39.57 mmol/g,enthalpy(H)and denaturation temperature increased(Td)(P<0.05).By mass spectrometry results of simulated gastric digestion products,it was found that oxidation adversely affected the digestion characteristics of WMP.It can be seen that the lipid oxidation product APPH of seed watermelon kernel can significantly affect the structure and function of the protein extracted from the seed kernel.

Protein adsorption, cell viability and corrosion properties of Ti6Al4V alloy treated by plasma oxidation and anodic oxidation

The hardness,wettability,and electrochemical properties of Ti6Al4V alloy surfaces treated with anodic oxidation and plasma oxidation as well as the viabilities of the different cell lines on the obtained surfaces were investigated.The anodic oxidation was performed for 10 min under 100 V potential,and it resulted in a 0.95μm thick nanoporous anatase-TiO2 structure.On the other hand,plasma oxidation was carried out at 650℃ for 1 h and resulted in a dense rutile-TiO2 structure with a thickness of 1.2μm.While a hardness of HV0.025823 and roughness of^220 nm were obtained by plasma oxidation,those obtained by anodic oxidation were HV0.025512 and^130 nm,respectively.The anodic oxidation process created a more hydrophilic surface with a contact angle of 87.2°.Both oxidation processes produced similar properties in terms of corrosion behavior and showed better resistance than the as-received state in a certain range of potential.Moreover,the surface treatments led to no significant change in the protein adsorption levels,which indicates that the difference in viability between the osteoblast and fibroblast cells was not due to the difference in surface protein adsorption.Given all the factors,the surfaces obtained by anodic oxidation treatment revealed higher cell viability than those obtained by plasma oxidation(p=0.05).

13C Protein Oxidation in Breath: Is It Relevant for the Whole Body Protein Status?

Introduction: The kinetics of protein oxidation, monitored in breath, and its contribution to the whole body protein status is not well established. Objectives: To analyze protein oxidation in various metabolic conditions we developed/validated a 13C-protein oxidation breath test using low enriched milk proteins. Method/Design: 30 g of naturally labeled 13C-milk proteins were consumed by young healthy volunteers. Breath samples were taken every 10 min and 13CO2 was measured by Isotope Ratio Mass Spectrometry. To calculate the amount of oxidized substrate we used: substrate dose, molecular weight and 13C enrichment of the substrate, number of carbon atoms in a substrate molecule, and estimated CO2-production of the subject based on body surface area. Results: We demonstrated that in 255 min 20% ± 3% (mean ± SD) of the milk protein was oxidized compared to 18% ± 1% of 30 g glucose. Postprandial kinetics of oxidation of whey (rapidly digestible protein) and casein (slowly digestible protein) derived from our breath test were comparable to literature data regarding the kinetics of appearance of amino acids in blood. Oxidation of milk proteins was faster than that of milk lipids (peak oxidation 120 and 290 minutes, respectively). After a 3-day protein restricted diet (~10 g of protein/day) a decrease of 31% ± 18% in milk protein oxidation was observed compared to a normal diet. Conclusions: Protein oxidation, which can be easily monitored in breath, is a significant factor in protein metabolism. With our technique we are able to characterize changes in overall protein oxidation under various meta-bolic conditions such as a protein restricted diet, which could be relevant for defining optimal protein intake under various conditions. Measuring protein oxidation in new-born might be relevant to establish its contribution to the protein status and its age-dependent development.

Effect of low protein diet combined with drug therapy on renal function and oxidation - anti-oxidation balance in patients with diabetic nephropathy

Objective:To study the effect of low protein diet combined with drug therapy on renal function and oxidation - anti-oxidation balance in patients with diabetic nephropathy.Methods: Patients with diabetic nephropathy who were treated in the Second People's Hospital of Deyang City between July 2014 and March 2017 were collected, retrospectively analyzed and then divided into two groups according to the application of low protein diet intervention or not, observation group received low protein diet combined with drug therapy, and control group accepted routine drug therapy. The contents of renal function indexes, oxidative products and antioxidant indexes in serum as well as the expression of podocyte injury markers in urine were measured before treatment and 3 months after treatment.Results: 3 months after treatment, BUN, Scr, CysC, Hcy, MDA and AOPP contents in serum as well asα-actinin-4, ZO-1, nephrin and podocinde mRNA expression in urine of both groups were lower than those before treatment whereas CAT, SOD and T-AOC contents in serum were higher than those before treatment, and BUN, Scr, CysC, Hcy, MDA and AOPP contents in serum as well asα-actinin-4, ZO-1, nephrin and podocinde mRNA expression in urine of observation group were lower than those of control group whereas CAT, SOD and T-AOC contents in serum were higher than those of control group.Conclusion:Low protein diet combined with drug therapy can improve the renal function and the oxidation - anti-oxidation balance in patients with diabetic nephropathy.

Relationship between the state of reduction-oxidation and protein degradation in the soleus muscle after scalding in rats

One hind leg(about 7% TBSA)of a rat was scalded and the changes of thereduction-oxidation state and protein degradation in the soleus muscle were observed inthe 72nd h after scalding both in vitro and in vivo.It was found that the lactate/pyruvate(L/P)and malate/pyruvate(M/P)ratios in the soleus muscle were significantly lower andthe protein degradation rate significantly higher in the scalded rats than those in the controland in the unscalded legs.After the addition of insulin to the medium,significant eleva-tion of L/P and M/P ratios and reduction of the protein degradation rate were observedin the soleus muscle.These findings suggest that there is a good correlation between thechanges of the reduction-oxidation and the protein degradation rate in the cytosol of thesoleus muscle after scalding in rats.

5-Hexylidene-4-propylamino-1,5-dihydroimidazol-2-one formed from Cu-catalyzed oxidation with implication for the structure of a His-Lys cross-link

Cu-catalyzed oxidation of 5-hexyl-1,3-dihydroimidazo-2-one (1) in the presence of propylamine, as surrogates for the oxidized His side chain and Lys side chain, was investigated. 5-Hexylidene-4-propylamino-1,5-dihydroimidazol-2-one (2), a model His-Lys cross-link product, was isolated and structurally characterized by NMR and mass spectrometry.

Significance of Fractional Exhaled Nitric Oxide Combined with Serum Procalcitonin and C-Reactive Protein in Evaluation of Elderly Asthma

Bronchial asthma is a common chronic airway inflammatory disease. Asthma is associated with high mortality, especially in the elderly patients. Repeated exacerbations cause disease progression. Therefore, identifying the onset of acute elderly asthma as soon as possible and giving the effective treatment is crucial to improve the prognosis. This study was to investigate the significance of fractional exhaled nitric oxide （FeNO） combined with serum procalcitonin （PCT） and C-reactive protein （CRP） in the evaluation of elderly asthma. A total of 120 elderly patients with an acute attack of asthma from July, 2010 to May, 2012 were studied. On presentation, FeNO, serum PCT and CRP concentrations were measured and sputum culture was also performed. The elderly patients were re-evaluated when they had returned to their stable clinical state. The elderly patients were classified into two groups： positive bac- terial culture group （A） and negative bacterial culture group （B）. The results showed that： （1） In patients with an acute exacerbation of asthma, 48 （40%） patients had positive sputum bacterial culture and 72 （60%） had negative sputum bacterial culture. （2） The levels of FeNO in patients with acute exacerbation of asthma were significantly higher than in those with no acute exacerbation state （63.8±24.6 vs. 19±6.5 ppb, P〈0.05）. There was no significant difference in FeNO between group A and group B （P〉0.05）. （3） The levels of PCT and CRP in group A patients with an acute exacerbation of asthma were significantly higher （P〈0.05） than in group B （for PCT： 27.46±9.32 vs. 7.85±3.52 ng/mL; for CRP： 51.25±11.46 vs. 17.11±5.87 mg/L, respectively）. When they had returned to stable clinical state, the levels of PCT and CRP in group A were decreased significantly （P〈0.05）, and those in group B had no significant change （P〉0.05） when compared with the exacerbation group. There were no significant differences in the levels of PCT and CRP between the two groups in non-acute exacerbation state （/9〉0.05）. These results suggest that the increase in FeNO indicates the acute exacerbation of asthma, and the elevation of serum PCT and CRP levels may be associated with bacterial infection.

Effect of Triptolide on Expression of Oxidative Carbonyl Protein in Renal Cortex of Rats with Diabetic Nephropathy

The traditional Chinese medicine（Tripterygium wilfordii Hook.f., TWH） has been clinically used to treat primary and secondary renal diseases and proteinuria for nearly 40 years. However, there is a rare literature about the effect of triptolide（the main active ingredient of TWH） on the expression of oxidative carbonyl protein（OCP） in diabetic nephropathy（DN）. This study aimed to provide experimental evidence for triptolide treatment on DN through its effect on the expression of OCP, in order to investigate the effects of triptolide on the expression of OCP in rats with DN. Sixty SD rats were randomly divided into five groups： control group, high-dose triptolide（Th） group, low-dose triptolide（Tl） group, DN model group, and positive control（benazepril） group. The DN model was established using streptozotocin. Urinary protein excretion, fasting blood glucose（FBG）, superoxide dismutase（SOD） in renal homogenate, malondialdehyde（MDA） in renal homogenate and renal nitrotyrosine by immunohistochemistry, and the expression of OCP by oxyblotimmune blotting were detected. In the DN model group, rat urinary protein excretion and renal MDA were significantly increased, while renal SOD significantly decreased and nitrotyrosine expression was obviously upregulated in the kidney. After triptolide treatment, 24-h urinary protein excretion（61.96±19.00 vs. 18.32±4.78 mg/day, P〈0.001）, renal MDA（8.09±0.79 vs. 5.45±0.68 nmol/L, P〈0.001）, and nitrotyrosine expression were decreased. Furthermore, renal OCP significantly decreased, while renal SOD（82.50±19.10 vs. 124.00±20.52 U/L, P〈0.001） was elevated. This study revealed that triptolide can down-regulate the expression of OCP in the renal cortex of DN rats.

Thioredoxin interacting protein,a key molecular switch between oxidative stress and sterile inflammation in cellular response

Tissue and systemic inflammation have been the main culprit behind the cellular response to multiple insults and maintaining homeostasis.Obesity is an independent disease state that has been reported as a common risk factor for multiple metabolic and microvascular diseases including nonalcoholic fatty liver disease(NAFLD),retinopathy,critical limb ischemia,and impaired angiogenesis.Sterile inflammation driven by high-fat diet,increased formation of reactive oxygen species,alteration of intracellular calcium level and associated release of inflammatory mediators,are the main common underlying forces in the pathophysiology of NAFLD,ischemic retinopathy,stroke,and aging brain.This work aims to examine the contribution of the pro-oxidative and pro-inflammatory thioredoxin interacting protein(TXNIP)to the expression and activation of NLRP3-inflammasome resulting in initiation or exacerbation of sterile inflammation in these disease states.Finally,the potential for TXNIP as a therapeutic target and whether TXNIP expression can be modulated using natural antioxidants or repurposing other drugs will be discussed.

Hyperammonemia induced oxidative stress in cirrhotic rats without promoting differential protein expression in the brain cortex: A 2D-DIGE analysis

Oxidative stress induced by a high ammonia concentration could modify protein expression in the brain. This study was undertaken in order to investigate the impact of hyperammonemia, caused by thioacetmide (TAA) in rats, on brain cortex protein expression using 2D-DIGE, and analyzing its role in the pathogenesis of HE. Hyperammonemia was induced with TAA. Ammonia and active oxidants were measured by L-glutamate dehydrogenase and dichlorodihydrofluorescein diacetate methods, respectively. Lipid peroxidation and protein oxidation biomarkers were also studied. Differential protein expression in the cortex of TAA- and control-rats was studied by 2D-DIGE. Image analysis was performed using the DeCyder? Software. Ammonia concentration in plasma and brain tissue was higher in TAA-rats compared to control-rats, 3.12 and 2.43 fold higher, respectively. Active oxidants production in TAA-rats was increased by 2.7 fold compared to control-rats. Measurements of MDA, HNE and carbonyl groups, biomarkers of lipid peroxidation and protein oxidation respectively, were found to be statistically significantly increased in TAA-rats compared to control-rats (3.16-, 2.44- and 1.95-fold, respectively), reflecting the presence of oxidative stress in the brain of TAA-rats. 2D-DIGE analysis of brain cortex protein allowed the detection of 2896 spots, however, image analysis showed no statistically significant differential protein expression between the proteins expressed in TAA- and control-rats. No statistical significant differential protein expression in the cortex of TAA-rats was observed, although oxidative stress biomarkers for lipid and proteins were higher in the brain of TAA-rats than in control-rats. These results support the idea that oxidative post-translational modifications are implicated in HE physiopathology.

C1q/TNF-related protein 1 promotes vasodilatory dysfunctions by increasing arginase 1 activity and uncoupling of endothelial nitric oxide synthase

Objective C1q/TNF-related protein(CTRP)1 was initiallyidentified as a paralog of adiponectin based on the similarity in C1q domain of these two proteins.Previously,we showed that CTRP1promotes the development of atherosclerosis by increasing endothelial adhesiveness.Here,we sought to investigate whether CTRP1 also influences vascular dilatory functions.

Polaprezinc protects human colon cells from oxidative injury induced by hydrogen peroxide:Relevant to cytoprotective heat shock proteins

AIM: To investigate the effect of polaprezinc on cellular damage induced by hydrogen peroxide (H2O2) in human colon CaCo2 cells. METHODS: CaCo2 cells were treated with polaprezinc (10-100 μmol/L) for 6 h. After polaprezinc treatment, the cells were incubated with H2O2 (20 μmol/L) for 1 h. Cell viability was measured by MTT assay. Western blot analysis for heat shock protein (HSP) 27 and HSP72 in the cells was performed. Moreover, cells were pretreated with quercetin (200 μmol/L), an inhibitor of HSP synthe- sis, 2 h before polaprezinc treatment, and cell viability and the expression of HSP27 and 72 were assessed in these cells. RESULTS: Polaprezinc significantly protected CaCo2 cells from cell damage induced by H2O2, and up-regulated the expressions of HSP27 and HSP72 in the cells (10, 30 and 100 μmol/L of polaprezinc; 35.0% ± 7.7%, 58.3% ± 14.6% and 64.2% ± 8.2%, respectively. P < 0.01 versus polaprezinc-nontreated cells; 6.0% ± 4.4%). Quercetin inhibited the up-regulation of HSP27 and HSP72 by pola- prezinc and diminished the protective effect of polaprez- inc against H2O2-caused injury in the cells. CONCLUSION: Polaprezinc is a useful therapeutic agent for treatment of colitis and its effects depend on the function of cytoprotective HSP in colon.