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.

fFabrication of three-dimensional proteinaceous micro- and nano-structures by femtosecond laser cross-linking

Proteins are a class of biomaterials having a vast array of functions, including the catalysis of metabolic reactions, DNA replication, stimuli response and transportation of molecules. Recent progress in laser-based fabrication technologies has enabled the formation of three-dimensional （3D） proteinaceous micro- and nano-structures by femtosecond laser cross-linking, which has expanded the possible applications of proteins. This article reviews the current knowledge andrecent advancements in the femtosecond laser cross-linking of proteins. An overview of previous studies related to fabri-cation using a variety of proteins and detailed discussions of the associated mechanisms are provided. In addition, ad-vances and applications utilizing specific protein functions are introduced. This review thus provides a valuable summaryof the 3D micro- and nano-fabrication of proteins for biological and medical applications.

A Facile Route for the Large Scale Fabrication of Graphene Oxide Papers and Their Mechanical Enhancement by Cross-linking with Glutaraldehyde

A facile route for the large scale production of graphene oxide(GO) papers and their mechanical enhancement has been presented in this work. The novel paper-like GO made from individual GO sheets in aqueous suspension can be achieved in large scale by a simple drop casting method on hydrophobic substrates.Significant enhancement in mechanical stiffness(341%) and fracture strength(234%) of GO paper have been achieved upon modification with a small amount(less than 10 wt%) of glutaraldehyde(GA). The cross-linking reaction takes place between hydroxyl groups on the surface of GO and aldehyde groups of GA, through forming hemiacetal structure, which can result in distinct mechanical enhancement of the GO papers.

Oxidative mechanism of chicken wooden breast myofibrillar protein

To explore the oxidation mechanism of wooden breast myofibrillar protein(WBMP),oxidative breast MP(OBMP)was obtained from different doses(3,10,and 20 mmol/L)of H2O2 oxidized normal breast MP(NBMP).The results showed that the Zeta-potential,particle size,solubility,sulfhydryl,and carbonyl contents of OBMP-3(3 mmol/L,low-dose free radicals)and WBMP were similar.Fluorescence spectrum analysis showed that the oxidation of low-dose free radicals led to a significant increase in the surface hydrophobicity(from 214.03±10.03 to 393.50±10.33)and tryptophan fluorescence intensity(from 185.71 to 568.32).In addition,theα-helix content of WBMP decreased significantly from(37.46±1.15)%(NBMP)to(34.70±2.04)%,whileβ-sheet and random coil contents increased significantly(P<0.05)from(14.37±0.69)%and(22.24±0.78)%(NBMP)to(17.70±0.87)%and(25.20±1.47)%(WBMP).In summary,low-dose free radical oxidation attacks protein groups,inducing secondary and tertiary structural changes,leading to the formation of WBMP.This work will provide a theoretical basis at the molecular level for exploring the mechanism of functional degradation of WBMP.

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 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.

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).

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.

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.

Antagonistic Effects of N-acetylcysteine on Mitogen-activated Protein Kinase Pathway Activation, Oxidative Stress and Inflammatory Responses in Rats with PM2.5 Induced Lung Injuries

Objective To evaluate the antagonistic effects of N-acetylcysteine(NAC)on mitogen-activated protein kinases(MAPK)pathway activation,oxidative stress and inflammatory responses in rats with lung injury induced by fine particulate matter(PM2.5).Methods Forty eight male Wistar rats were randomly divided into six groups:blank control group(C1),water drip control group(C2),PM2.5 exposed group(P),low-dose NAC treated and PM2.5 exposed group(L),middle-dose NAC treated and PM2.5 exposed group(M),and high-dose NAC treated and PM2.5 exposed group(H).PM2.5 suspension(7.5 mg/kg)was administered tracheally once a week for four times.NAC of 125 mg/kg,250 mg/kg and 500 mg/kg was delivered intragastrically to L,M and H group respectively by gavage(10 ml/kg)for six days before PM2.5 exposure.The histopathological changes and human mucin 5 subtype AC(MUC5AC)content in lung tissue of rats were evaluated.We investigated IL-6 in serum and bronchoalveolar lavage fluid(BALF)by Enzyme-linked immunosorbent assay(ELISA),MUC5AC in lung tissue homogenate by ELISA,glutathione peroxidase(GSH-PX)in serum and BALF by spectrophotometry,and the expression of p-ERK1/2,p-JNK1/2 and p-p38 proteins by Western blot.All the measurements were analyzed and compared statistically.Results Lung tissue of rats exposed to PM2.5 showed histological destruction and increased mucus secretion of bronchial epithelial cells.Rats receiving NAC treatment showed less histological destruction and mucus secretion.Of P,L,M and H group,MUC5AC in lung tissue,IL-6 in serum and BALF were higher than controls(C1 and C2)(all P<0.05),with the highest levels found in the P group and a decreasing trend with increase of NAC dose.The activity of GSH-PX in serum and BALF of PM2.5 exposed rats(P,L,M and H)was lower than that of controls(all P<0.05),with higher activities found in NAC treated rats(L,M,and H),and an increasing trend with increase of NAC dose.The expressions of p-ERK1/2,p-JNK1/2 and p-p38 proteins in PM2.5 exposed lung tissue(P,L,M and H)was higher than controls(all P<0.05),with decreased levels and dose dependent downregulation found in NAC treated rats.Conclusion NAC can antagonize major MAPK pathway activation,lung oxidative stress and inflammatory injury induced by PM2.5 in rats.

Comparison of Adsorption of Proteins at Different Sizes on Pristine Graphene and Graphene Oxide

Using all-atom molecular dynamics （MD） simulations, we have investigated the adsorption stability and conformation change of different proteins on the surface of pristine graphene （PG） and graphene oxide （GO）. We find that： （i） with the cooperation of the electrostatic interactions between proteins and oxygen-containing groups, GO shows better adsorption stability than PG; （ii） the peptide loses its secondary structure on both PG and GO surface, and the a-helix structure of the protein fragment is partially broken on PG surface, but is well preserved on GO surface, while the secondary structure of globular protein has no distinct change on both PG and GO surface. In general, GO presents better biocompatibility than PG. Our results are of significant importance to understand the interactions between proteins and PG/GO and the applications of PG/GO in biotechnology and biomedicine.

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.

C-reactive protein,procalcitonin,interleukin-6,vascular endothelial growth factor and oxidative metabolites in diagnosis of infection and staging in patients with gastric cancer

AIM:The current study was to determine the serum/pLasma levels of VEGF,IL-6,malondialdehyde (MDA),nitric oxide (NO),PCT and CRP in gastric carcinoma and correlation with the stages of the disease and accompanying infection. METHODS:We examined the levels of serum VEGF,IL-6, PCT,CRP and plasma MDA,NO in 42 preoperative gastric cancer patients and 23 healthy subjects.There were infection anamneses that had no definite origin in 19 cancer patients. RESULTS:The VEGF levels (mean±SD; pg/mL) were 478.05±178.29 and 473.85±131.24 in gastric cancer patients with and without infection,respectively,and these values were not significantly different (P>0.05).The levels of VEGF, CRP,PCT,It-6,MDA and NO in cancer patients were significantly higher than those in healthy controls and the levels of CRP,PCT,It-6,MDA and NO were statistically increased in infection group when compared with non- infection group (P<0.001). CONCLUSION:Although serum VEGF concentrations were increased in gastric cancer,this increase might not be related to infection.CRP,PCT,IL-6,MDA and NO have obvious drawbacks in the diagnosis of infections in cancer patients. These markers may not help to identify infections in the primary evaluation of cancer patients and hence to avoid unnecessary antibiotic treatments as well as hospitalization. According to the results of this study,IL-6,MDA,NO and especially VEGF can be used as useful parameters to diagnose and grade gastric cancer.

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.

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 （H202） in human colon CaCo2 cells. METHODS： CaCo2 cells were treated with polaprezinc （10-100 pmol/L） for 6 h. After polaprezinc treatment, the cells were incubated with H202 （20μmol/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 synthesis, 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 pmol/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 polaprezinc and diminished the protective effect of polaprezinc 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.