Effect of exogenous free N^(ε)-(carboxymethyl)lysine on diabetes-associated cognitive dysfunction:neuroinflammation,and metabolic disorders

Diabetes-associated cognitive dysfunction has already been attracted considerable attention.Advanced glycation end products(AGEs)from daily diets are thought to be a vital contributor to the development of this diseases.However,the effect of one of the best-characterized exogenous AGEs N^(ε)-(carboxymethyl)lysine(CML)on cognitive function is not fully reported.In the present study,diabetical Goto-Kakizaki(GK)rats were treated with free CML for 8-weeks.It was found that oral consumption of exogenous CML significantly aggravated diabetes-associated cognitive dysfunction in behavioral test.In details,exogenous CML increased levels of oxidative stress,promoted the activation of glial cells in the brain,up-regulated the release of inflammatory cytokines interleukin-6,inhibited the protein expression of the brain-derived neurotrophic factor and thus led to neuroinflammation.Furthermore,exogenous CML promoted the amyloidogenesis in the brain of GK rats,and inhibited the expression of GLUT4.Additionally,several tricarboxylic acid cycle and glutamate-glutamine/γ-aminobutyric acid cycle intermediates including pyruvate,succinic acid,glutamine,glutamate were significantly changed in brain of GK rats treated with exogenous free CML.In conclusion,exogenous free CML is a potentially noxious compounds led to aggravated diabetes-associated cognitive dysfunction which could be possibly explained by its effects on neuroinflammation,energy and neurotransmitter amino acid homeostasis.

Nε-(carboxymethyl)lysine promotes lipid uptake of macrophage via cluster of differentiation 36 and receptor for advanced glycation end products

BACKGROUND Advanced glycation end products(AGEs)are diabetic metabolic toxic products that cannot be ignored.Nε-(carboxymethyl)lysine(CML),a component of AGEs,could increase macrophage lipid uptake,promote foam cell formation,and thereby accelerate atherosclerosis.The receptor for AGEs(RAGE)and cluster of differentiation 36(CD36)were the receptors of CML.However,it is still unknown whether RAGE and CD36 play key roles in CML-promoted lipid uptake.AIM Our study aimed to explore the role of RAGE and CD36 in CML-induced macrophage lipid uptake.METHODS In this study,we examined the effect of CML on lipid uptake by Raw264.7 macrophages.After adding 10 mmol/L CML,the lipid accumulation in macrophages was confirmed by oil red O staining.Expression changes of CD36 and RAGE were detected with immunoblotting and quantitative real-time polymerase chain reaction.The interaction between CML with CD36 and RAGE was verified by immunoprecipitation.We synthesized a novel N-succinimidyl-4-18Ffluorobenzoate-CML radioactive probe.Radioactive receptor-ligand binding assays were performed to test the binding affinity between CML with CD36 and RAGE.The effects of blocking CD36 or RAGE on CML-promoting lipid uptake were also detected.RESULTS The study revealed that CML significantly promoted lipid uptake by macrophages.Immunoprecipitation and radioactive receptor-ligand binding assays indicated that CML could specifically bind to both CD36 and RAGE.CML had a higher affinity for CD36 than RAGE.ARG82,ASN71,and THR70 were the potential interacting amino acids that CD36 binds to CML Anti-CD36 and anti-RAGE could block the uptake of CML by macrophages.The lipid uptake promotion effect of CML was significantly attenuated after blocking CD36 or RAGE.CONCLUSION Our results suggest that the binding of CML with CD36 and RAGE promotes macrophage lipid uptake.

Advances in Toxicology of Nε-(carboxymethyl)-lysine(CML)

Advanced glycation end-products （AGEs） are products of non-enzymatic glycation of proteins, lipids or nucleic acids and other macromolecules. To be spe- cific, Nε-（carboxymethyl）-Iysine （CML） is one of the most important components of AGEs, which is wildly distributed in the body and can be formed in vivo or in food processing and heating processes. Previous studies have shown that CML is a ma- jor immunological epitope in AGEs and plays an important role in diabetes and its complications, as well as in the development and progression of aging. This review summarized recent advances in major source, toxicological hazard and control mea- sures of CML.

Dietary Nε-(carboxymethyl)lysine affects cardiac glucose metabolism and myocardial remodeling in mice

BACKGROUND Myocardial remodeling is a key factor in the progression of cardiovascular disease to the end stage.In addition to myocardial infarction or stress overload,dietary factors have recently been considered associated with myocardial remodeling.Nε-(carboxymethyl)lysine(CML)is a representative foodborne toxic product,which can be ingested via daily diet.Therefore,there is a marked need to explore the effects of dietary CML on the myocardium.AIM To explore the effects of dietary CML(dCML)on the heart.METHODS C57 BL/6 mice were divided into a control group and a dCML group.The control group and the dCML group were respectively fed a normal diet or diet supplemented with CML for 20 wk.Body weight and blood glucose were recorded every 4 wk.^(18)F-fluorodeoxyglucose(FDG)was used to trace the glucose uptake in mouse myocardium,followed by visualizing with micro-positron emission tomography(PET).Myocardial remodeling and glucose metabolism were also detected.In vitro,H9C2 cardiomyocytes were added to exogenous CML and cultured for 24 h.The effects of exogenous CML on glucose metabolism,collagen I expression,hypertrophy,and apoptosis of cardiomyocytes were analyzed.RESULTS Our results suggest that the levels of fasting blood glucose,fasting insulin,and serum CML were significantly increased after 20 wk of dCML.Micro-PET showed that ^(18)F-FDG accumulated more in the myocardium of the dCML group than in the control group.Histological staining revealed that dCML could lead to myocardial fibrosis and hypertrophy.The indexes of myocardial fibrosis,apoptosis,and hypertrophy were also increased in the dCML group,whereas the activities of glucose metabolism-related pathways and citrate synthase(CS)were significantly inhibited.In cardiomyocytes,collagen I expression and cellular size were significantly increased after the addition of exogenous CML.CML significantly promoted cellular hypertrophy and apoptosis,while pathways involved in glucose metabolism and level of Cs mRNA were significantly inhibited.CONCLUSION This study reveals that dCML alters myocardial glucose metabolism and promotes myocardial remodeling.

Assessing Lysine Requirement of Growing Chicken by Direct Comparison between Supplementation Technique and “Goettingen Approach”

Validated procedures play an important role to obtain accurate information about individual amino acid requirement data. The aim of the present study was to assess lysine (Lys) requirement of growing chicken both by classical supplementation technique and principles of diet dilution technique as applied with “Goettingen approach”. During the starter period (1 - 21 d), a growth study with male meat type chicken (Ross 308) was conducted making use of five graded dietary Lys-levels (3 repetition boxes with 3 birds/box). L-Lys×HCl was gradually added to a diet based on wheat, soybean protein concentrate, wheat gluten and fishmeal to yield 80%, 87.5%, 95%, 102.5% and 110% of the expected requirement level (13 g Lys/kg as fed). Diets were iso-energetic (12.8 MJME/kg) and iso-nitrogenous (21.65% crude protein). Birds were fed on free choice level also to assess the feed intake (FI) effects as important factor on traditional response criteria. Analyzed body composition at start and end of the growth study yielded N deposition (ND) data for further data assessment using exponential approximations depending on dietary Lys content or observed Lys intake. The results indicated significant differences (p < 0.05) in response on body weight gain (BWG) and observed dietary protein quality with unexpected consequences for the derived Lys requirement data. According to the independent variable (Lys in % of diet versus daily Lys intake) and aimed level of daily ND, the needed in-feed content of Lys varied between 1.24% and 1.46%. Application of the exponential modelling by “Goettingen approach” overcame these misleading conclusions by modelling the relationship between required Lys intake and observed response data (BWG, ND) taking also into account the expected real feed intake to formulate the needed in-feed concentration.

Validation of the Lysine Requirement as Reference Amino Acid for Ideal In-Feed Amino Acid Ratios in Modern Fast Growing Meat-Type Chickens

Nitrogen (N) balance studies were conducted with male growing broiler chickens to reevaluate the lysine (Lys) requirement of a modern broiler strain (Ross 308), making use of eight diets with graded crude protein (CP) supply (6% - 34% CP as-fed). Wheat, soy protein concentrate, wheat gluten, fishmeal and crystalline amino acids (AAs) were the protein sources in the experimental diets with Lys as limiting AA. Following an adaptation period of five days, two consecutive excreta collection periods (2 × 5 d) were conducted: 10 - 20 d of age (starter period) and 25 - 35 d of age (grower period). Statistical evaluation of N balance data utilized an exponential modelling approach. Based on different dietary Lys efficiency, Lys requirement data were derived by modelling depending on average body weight (BW) during starter and grower period and targeted body protein deposition (PD), respectively. In addition, the influence of graded feed intake was taken into account. For the starter period at 600 g BW and assumed 10 g daily body PD, Lys requirement data between 741 mg and 823 mg per day were observed. The corresponding Lys in-feed concentration was 1.06% and 1.18%, dependent on supposed Lys efficiency at 70 g daily feed intake. For the grower period (average BW 1800 g), 1272 mg to 1473 mg Lys per day was needed to yield 16.5 g daily PD. The corresponding required Lys in-feed concentration was between 0.85% and 0.94% Lys for 150 g daily feed intake.

An Elevated Dietary Cysteine to Methionine Ratio Does Not Impact on Dietary Methionine Efficiency and the Derived Optimal Methionine to Lysine Ratio in Diets for Meat Type Chicken

Optimal dietary methionine (Met) to lysine (Lys) ratio in presence of elevated dietary cysteine (Cys) levels was derived for meat type growing chicken. Twelve averaged weighed Ross 308 birds (each 50% of male and female per dietary treatment) were utilized in N balance trials. During starter (d10 - 20) and grower period (d25 - 35) five dietary treatments were used. Diets based on uniform mixtures of maize, wheat, soybean meal, potato protein and fish meal were supplemented with crystalline amino acids (AA). In diets 1 - 3, the dietary Cys to Met ratio was set as 85, 95 and 105 to 100, respectively. Diet 4, at a Cys to Met ratio of 105 to 100, was additionally supplemented with betaine (BET) as methyl group donor. Diets 1 - 4 were limiting in Met, diet 5 without L-Lys·HCl addition was limiting in Lys. Individual N-balance data per treatment were utilized for assessing protein quality and efficiency of dietary Met (Diets 1 - 4) or Lys (Diet 5) based on “Goettingen approach”. Elevated dietary Cys supply and supplemented BET failed to improve both dietary protein quality and Met efficiency. The established optimal Met to Lys ratio was on average 34 to 100 for growing chicken during starter and grower period, respectively.

PNIPAm@CMCS生物基水凝胶吸附染料研究

针对目前皮革废水处理剂难回收问题,以羧甲基壳聚糖(CMCS)和聚N-异丙基丙烯酰胺(PNIPAm)为原料,合成一种兼具优异吸附性和可重复利用且易回收的生物基水凝胶(PNIPAm@CMCS),并对该水凝胶的抗疲、亲水、溶胀、吸附及抗菌等性能进行了研究。结果表明,所制备的生物基水凝胶具有出色的抗疲性(耐循环压缩15次)、溶胀率(2034%)、吸附性(伊红Y=587 mg/g,罗丹明=444 mg/g,甲基橙=621 mg/g)和抗菌性能(抗菌率=100%)。该生物基水凝胶作为一类高效、环保的染料废水处理剂,展现了广阔的应用前景,有望为制革工业处理含染料污水提供新的思路。

Blood Compatibility of Amphiphilic Poly(N-α-acrylamide-L-lysine-<i>b</i>-dimethylsiloxane) Block Copolymers

Amphiphilic block copolymers poly(LysAA-b-DMS) consisting of a hydrophilic poly(N-α-acrylamide-L-lysine) [poly(LysAA)] segment with different molecular weights and a hydrophobic polydimethylsiloxane (PDMS) segment were prepared as follows. The precursor copolymer poly(Boc-LysAA-OtBu-b-PDMS) was obtained from radical polymerization of N-α-acrylamide-N-ε-tert-butoxycarbonyl-L-lysine-tert-butylester (Boc-LysAA-OtBu) initiated with 4,4’-azobis(polydimethylsiloxane 4-cyanopentanoate) (azo-PDMS) with the molecular weight of PDMS Mw = 4.3 × 103 in the presence of 2-mercaptoethanol (2-ME) as a chain-transfer agent. Removal of the protecting groups of the precursor copolymer was carried out in 80% trifluoroacetic acid aqueous solution to give poly(LysAA-b-DMS)-1-3. The weight average molecular weight of poly(LysAA-b-DMS)-1-3 was Mw = 1.02 × 104 – 2.52 × 104. From the 1H-NMR and fluorescence spectra measurements, poly(LysAA-b-DMS)-1-3 was determined to self-organize and form core-shell micelles in water. The critical micelle concentration (CMC) increased to 1000 - 4000 mg·L–1 with increasing molar ratio of the poly(LysAA) segment from 0.42 to 0.65. From morphological analysis with a scanning probe microscope (SPM), poly(LysAA-b-DMS) has microphase-separated structures made up of hydrophilic and hydrophobic regions with the domain size ranging from several tens to several hundreds of nanometers. Inhibition of thrombin activity of poly(LysAA-b-DMS) was evaluated from the Michaelis constant (KM) and catalytic activity (kcat) for the enzymatic reaction of thrombin and synthetic substrate S-2238 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.10 - 0.11 mM and 4.04 × 105 – 4.26 × 105 min–1, respectively. Fibrinolytic activity was also verified from the transformation of plasminogen to plasmin by tissue plasminogen activator (t-PA) using synthetic substrate S-2251 in the presence of poly(LysAA-b-DMS). The KM and kcat were 0.07 mM and 5.73 × 106 –5.95 × 106 min–1, respectively.

Absorption Capability Comparison of Two Kinds of Super Absorbent Resins from Carboxymethyl Cellulose

The two kinds of super absorbent resins from carboxymethyl cellulose were synthesized with the potassium persulphate and methylenebisacrylamide as initiator and cross linker respectively by radical polymerization in aqueous solution. Thestructures of the two resins were characterized with Fourier transform infrared spectroscopy FTIR, scanning electron miscroscopy （SEM）, and environment scanning electron miscroscopy （ESEM）, the results indicate that the fibriform of the carboxymethyl cellulose （CMC） is disappeared and the crusslink networks in eopolymer of carboxymethyl cellulose-graft-polyacrylic acid（CMC-g-PAA） are denser than that of eopolymer of carboxymethyl cellulose-graft-poly （acrylic acid-co-N-vinyl Pyrrolidone） （CMC-g- PAA-co-PVP）. The comparison between the two resins in absorption capacities is that CMC-g-PAA is better in the water-keep capability being heated, while CMC-g-PAA-co-PVP is better in the water absorbency and salt resistance.

Preparation and Compressive Strength of Calcium Phosphate Bone Cement Containing N,O-carboxymethyl Chitosan

N, O-carboxymethyl chitosan （ CMCTS ）, a kind of biodegradable organic substance, was added to calcium phosphate bone cement （CPC） to prodnce a composite more similar in composition to human bone. The compressive strength of the new material was inereased by 10 times compared with conventional CPC.

Preparation and characterization of N-isopropylacrylamide/carboxymethylated chitosan hydrogel

Poly （N-isopropylacrylamide） （PNIPAAm）/carboxymethylated chitosan （CMCH） hydrogels were prepared by irradiating the aqueous solution mixture of NIPAAm and CMCH by 60 Co γ-ray.The effects of feed ratio of NIPAAm and CMCH,temperature,pH and ionic strength on the swelling ratio of PNIPAAm/CMCH hydrogels were studied.The results show that the addition of CMCH shifts the lower critical solution temperature （LCST） of the PNIPAAm hydrogel to higher temperature.The PNIPAAm/CMCH hydrogel displays not only pH-and thermo-sensitivity,but also ion-sensitivity.Differential scanning calorimetry （DSC） was applied for the determination of the LCST of the hydrogel.

Adsorption of Pharmaceutical Contaminants from Aqueous Solutions Using N,O-Carboxymethyl Chitosan/Polyethylene Oxide (PEO) Electrospun Nanofibers

Residues of pharmaceutical and direct metabolites discharged into the aquatic environment have become a challenge for wastewater treatment facilities due to their increase in concentration and their different physicochemical properties. These emerging contaminants are daily detected in surface water and wastewater discharged by municipalities. To remediate the contaminated water, various methods are currently used including primary, secondary, and tertiary advanced treatments. However, some economic and environmental limitations have forced the scientific community to develop alternative disinfection processes to purify wastewater. As such, the adsorption strategy represents a “green” low-cost and effective solution to remove pollutants from water. In this study, a nanomaterial made of N,O-carboxymethyl chitosan (N,O-CMCS) was prepared using chitosan (CS) and monochloroacetic acid under various conditions. N,O-CMCS electrospun was synthetized with the copolymer polyethylene oxide (PEO) to create nanofiber membranes showing a better specificity toward diversified contaminants depending on the pH of medium. The developed adsorbent was used to remove fluoxetine (FLX) from aqueous solutions. The new nanomaterial was characterised using FTIR, NMR, and SEM techniques. Sorption batch tests were carried out using high-performance liquid chromatography and ultraviolet diode array detector (HPLC-UV DAD) under controlled pH experimental conditions to determine the contaminant removal capacity of the nanomaterial. The promising adsorption results obtained with N,O-CMCS/PEO nanofibers are among the best ones obtained so far in comparison to other commercial and synthetized adsorbents tested for FLX’s adsorption. Kinetic experiments were also performed to investigate effects of contact times on the FLX adsorption. Experimental results were fitted to both common kinetic models pseudo-first and second order. The latter kinetic model described the best the sorption on surface. It revealed a possible chemisorption mechanism with electrostatic bounding for N,O-CMCS/PEO nanofibers.

多酚对热加工食品中羧甲基赖氨酸的抑制机理研究进展

食品中的羧甲基赖氨酸是还原糖与蛋白质、氨基酸等通过美拉德反应产生的晚期糖基化终末产物中的一种主要成分,与人体许多疾病的发生密切相关。天然多酚的使用是控制食品中CML的主要手段。简要综述了食品中羧甲基赖氨酸的普遍存在性,从抗氧化性和抓捕性能来讨论多酚抑制CML形成的研究进展,在此基础上提出未来研究的展望。

基于生信分析探讨KMT2家族调节肝癌微环境免疫细胞浸润特性研究

目的探讨组蛋白赖氨酸N-甲基转移酶2(KMT2)家族在肝癌微环境免疫细胞浸润中的作用。方法利用多种数据库探究KMT2家族在肝癌中的表达水平、预后价值及与微环境免疫细胞浸润的相关性。结果KMT2家族在肝癌组织中的表达水平显著上调,并与患者不良预后相关。KMT2家族与肿瘤微环境(TME)免疫细胞浸润水平及几乎所有免疫检查点(ICP)基因密切相关。结论KMT2家族在肝癌中的表达水平显著上调,且在TME免疫细胞浸润中发挥重要作用,具有成为肝癌免疫治疗候选靶点的潜在价值。

杏鲍菇空气煎炸过程品质变化与羧甲基赖氨酸、羧乙基赖氨酸生成研究

本文以杏鲍菇脆片为研究对象,分别采用荧光光谱法和超高效液相色谱-三重四极杆串联质谱法测定脆片中荧光性晚期糖基化终末产物(Advanced glycation end products,AGEs)以及2种极具代表性的典型晚期糖基化终末产物羧甲基赖氨酸(N^(ε)-carboxymethyl-lysine,CML)和羧乙基赖氨酸(N^(ε)-carboxyethyl-lysine,CEL)的含量,并研究不同煎炸温度、时间对杏鲍菇品质的影响。结果表明:杏鲍菇脆片在煎炸过程中发生了褐变,色泽开始由白色变成金黄色,时间越长、温度越高,颜色越深。脆片的水分含量显著(P<0.05)减少,硬度变化趋势为先减小后增大,且在煎炸过程中,煎炸时间和温度对杏鲍菇中CML和CEL的形成均具有显著(P<0.05)的影响,其含量随着煎炸温度和煎炸时间的增加而不断增加。在180℃、20 min下,CML和CEL的含量达到了最高,分别是13.75和70.63μg/g。但荧光AGEs的生成量在180℃、10 min要比160℃、10 min高4.5 AU。在160℃、10 min下,CML和CEL的含量分别是4.54和8.34μg/g,相比于160℃、20 min下,分别减少了46.65%和62.48%,且在此条件下感官评定较好,与180℃、10 min差异不显著,同时生成的AGE较少。因此结合各个指标的测定结果和感官评价,最终确定杏鲍菇脆片最佳煎炸条件为160℃、10 min。

羧甲基壳聚糖(NCMC)对玉米幼苗氮代谢有关酶活性的影响

用０．２％的羧甲基壳聚糖（ＮＣＭＣ）水溶液处理玉米种子和幼苗，其幼苗中硝酸还原酶活性比对照提高３０％～６０％；谷氨酸脱氢酶活性比对照普遍提高；而蛋白水解酶活性比对照降低１５％～３４％。

高取代度N,O-羧甲基壳聚糖的合成及其对水中Cu^(2+)的螯合絮凝性能

以壳聚糖为原料 ,通过两段加碱法制备出取代度 1.0以上的 N,O-羧甲基壳聚糖 ,对其螯合 Cu2 + 机理进行了研究 ;考察了取代度、脱乙酰度、样品用量、溶液初始 Cu2 + 浓度及 p H值等因素对螯合能力的影响 ,以及螯合物的解附 .结果表明 ,取代度直接影响螯合能力 ,高取代度羧甲基壳聚糖对 Cu2 +螯合能力很强 ,其螯合反应在几 min内便接近平衡 ,且取代度为1.63时 ,在 Cu2 +初始浓度 4 .82 66× 10 - 4mol/ L 的稀溶液中 ,螯合容量可达 189mg/ g样品 .

空气煎炸温度和时间对香菇品质和晚期糖基化终末产物形成的影响

研究空气煎炸温度和时间对香菇(Lentinulaedodes)品质和晚期糖基化终末产物(advanced glycation end products, AGEs)形成的影响。以香菇为原料,通过不同温度(160、180℃)和时间(0、5、10、15、20min)的空气煎炸,测定香菇含水量、色泽、硬度,进行感官评定,并分析香菇中荧光性AGEs和非荧光性AEGs——羧甲基赖氨酸(Nε-(carboxymethyl)-lysine, CML)和羧乙基赖氨酸(Nε-(carboxyethyl)-lysine, CEL)3种美拉德反应产物的含量。结果表明:空气煎炸10、15、20 min时,180℃处理香菇的含水量显著低于160℃;其中180℃,空气煎炸20 min时,香菇含水量最低。与新鲜香菇相比,180℃空气煎炸20 min时亮度值L*最低,红度值a*、黄度值b*、色泽总差值ΔE和硬度最高。160、180℃时,与空气煎炸5 min相比,20 min时形态得分、色泽得分、香味得分、综合得分最低;180℃空气煎炸10 min的酥脆度最高。与新鲜香菇相比,180、160℃空气煎炸10 min时荧光性AGEs含量差异不显著,180℃时空气煎炸20 min时,荧光性AGEs含量最高;160℃空气煎炸20 min的CML含量最高;180℃空气煎炸20 min的CEL含量最高;160、180℃空气煎炸10 min时CML和CEL含量差异不显著。综上,180℃、10min为空气煎炸香菇的良好条件,此时香菇的色泽风味及口感均良好且荧光性AGEs、CEL及CML含量较低。

N,O-羧甲基壳聚糖与磷酸三钙复合体的理化性能研究

目的:研究N,O-羧甲基壳聚糖(N,O-carboxymethyl chitosan,N,O-CMCS)/磷酸三钙(tricalcium phosphate,TCP)以不同质量比例复合制作骨支架材料的理化性能。方法:N,O-CMCS与TCP分别以质量比2∶1、1∶1和1∶2混合,以同体积的水将材料调匀,制成复合体,应用红外光谱仪测试复合材料的特征谱带,扫描电镜观察复合材料的微观特征,万能材料实验机测试材料复合后15min和12h时的抗压强度和弹性模量。结果:3种复合材料中,N,O-CMCS的-COO-和-NH2的特征峰渐向低波数方向明显位移,-COO-和-NH2与TCP的Ca2+发生了络合反应。N,O-CMCS/TCP呈三维结晶多孔结构,N,O-CMCS含量增多,复合材料孔隙增加,抗压强度变大;而TCP含量增多,其孔隙减少,弹性模量变大,刚性加强。结论:N,O-CMCS具有络合钙粒子的特性,与TCP复合后形成的复合材料具有良好的可塑性、三维多孔结构和力学性能,有望成为一种有应用前景的骨修复材料。