高相对分子质量甲壳素、壳聚糖的制备

采用红外光谱分析甲壳素、壳聚糖的主要性能指标，研究了EDTA和HCI用于制备甲壳素的脱钙工艺，其结果为：EDTA可替代HCI用于制备甲壳素的脱钙工艺，特别是由于其所特有的脱钙机理，脱钙时对甲壳素碳骨架基本无损伤，因此其产品的分子质量较HCI法的大，在同等条件下，可制得高相对分子质量的甲壳素和壳聚糖。其它性能指标如产率，脱乙酰度，颜色等均优于采用HCI法制得的产品。此外，EDTA法还可减少环境污染，而不增加成本。     

甲壳素及壳聚糖的医药应用

甲壳素是广泛存在于自然界的一种天然高分子材料，壳聚糖为其脱乙酰基衍生物。本文着重介绍甲壳素及壳聚糖在医药学上的应用。     

掸子虫壳聚糖的制备及其性能研究

从掸子虫壳中分离出甲壳素,并与蟹壳甲壳素进行了脱乙酰化的比较。掸子虫甲壳素有相对较高的脱乙酰度。红外光谱和Ｘ衍射表明,掸子虫甲壳素和壳聚糖有相对弱的分子间作用力及较低的结晶性,因而在理化性质上表现出了较高的亲水性和保湿性,更适宜作医用缓解辅料。     

甲壳化学的研究进展与应用概况

本文对甲壳素化学的基本框架以及3种关键物质——甲壳素、壳聚糖和寡聚糖的研究与应用进展作一综述.主要内容包括甲壳素的来源及提取、甲壳素脱乙酰化制备壳聚糖、通过壳聚糖降解和改性两种途径制备水溶性壳聚糖以及壳寡糖在医药、食品、化妆品和农业领域的应用.     

甲壳素及壳聚糖制备方法的改进

目的优化甲壳素及壳聚糖的制备方法。方法采用分步浸酸、浸碱法制备甲壳素及壳聚糖。结果蟹壳中甲壳素提取率为18.56%;壳聚糖脱乙酰度为91.25%,黏均分子量为8.29×105。结论分步法较一步法更能制备出高质量的甲壳素及壳聚糖。     

甲壳素及其衍生物在医药敷料中的应用进展

甲壳素，又称甲壳质、几丁质，是天然多糖类高分子物质，化学名为β-1，4-2-乙酰氨基-2-脱氧-D-葡萄糖，分子式（C8H13NO5）a，不溶于水、稀酸、稀碱和一般有机溶剂，具有α、β、γ三种晶型，广泛存在于虾蟹壳、昆虫外壳、真菌细胞壁、植物细胞壁中。甲壳素经脱乙酰基后的产物称为壳聚糖，也称几丁聚糖、脱乙酰甲壳素、可溶性甲壳素、甲壳胺等。     

甲壳素制备工艺改进——天然甲壳素的提取

甲壳素制备工艺改进为统一常温进行,操作简便,产品相对收率提高5～10％,同时降低了能耗、机械要求强度、劳动保护条件和生产成本,并经热分析说明产品维持了甲壳素的天然特性,即分子中每结构单元含有1/2分子缔合水,是天然的甲壳素产品并有益于其脱乙酰化物──壳聚糖质量的提高。     

甲壳素及其衍生物在烧伤、烫伤方面的药理作用及其应用

甲壳素(chitin)又名几丁质、甲壳质、壳多糖等,广泛存在于甲壳纲动物如蟹、虾、昆虫及真菌中,其资源丰富,产量仅次于纤维素,是自然界第二大有机物质.壳聚糖(chitosan)是甲壳素最重要的衍生物,是甲壳素部分或全部脱乙酰基的产物.自1811年Braconnol发现甲壳素和1894年Hoppe将甲壳素与KOH在180℃下熔融得到壳聚糖以来,人们对此类化合物进行了大量的基础和应用研究,揭示了其在食品、美容、纺织、环境保护、农业、生物等一系列领域的应用价值.近年来,随着高分子科学和生物医学工程的发展,甲壳素及其衍生物在医药方面的应用研究也日益增多.国内、外多项实验已经证明,甲壳素及其衍生物具有多种药理作用,临床用于治疗相关病症收到了良好的效果.本文中,笔者将对甲壳素及其衍生物在烧伤、烫伤方面的药理作用及其应用做一综述.     

甲壳素的理化研究 Ⅰ.分子量的测定

为测定甲壳素的分子量,本文首先在温和条件下将其脱乙酸化制得壳聚糖,然后用粘度法测定壳果糖的分子量,基于二者聚合度基本一致,推导出甲壳素分子量约为1×10~6。     

甲壳素及其衍生物壳聚糖的应用进展

甲壳素(Chitin)是自然界中含氨基的均态多糖之一,广泛存在于甲壳类动物中,是仅次于纤维素的天然高分子化合物.壳聚糖(Chitosan)是甲壳素脱乙酰基产生的主要衍生物.甲壳素结构中含有多种官能团,壳聚糖分子中存在许多游离胺基,因而具有许多独特的性质.同时,二者具有很好的生物相容性,可降解性等特点,因而在许多领域具有广泛的应用.     

CDA deficiency as a possible culprit for life-threatening toxicities after cytarabine plus 6-mercaptopurine therapy: pharmacogenetic investigations

We describe here the case of a 7-year old girl with lymphoma who developed life-threatening toxicities upon cytarabine plus mercaptopurine. Surprisingly, initial investigations on canonical thiopurine methyltransferase genetic polymorphism proved to be negative. We focused next on deregulations affecting the CDA gene implicated in the liver disposition of cytarabine. This patient was homozygous for both the 79A>C and the -31delC polymorphisms on the CDA gene and promoter, two genotypes with reported opposite effects on CDA phenotype. To determine the CDA status of this patient, additional functional testing was performed and eventually demonstrated that this patient was a poor metabolizer. This case demonstrates that besides affecting thiopurine methyltransferase, dysregulations with CDA should be screened to anticipate toxicities with the cytarabine plus mercaptopurine combination.     

Block of peripheral nerve sodium channels selectively inhibits features of neuropathic pain in rats

Several sodium channel blockers are used clinically to treat neuropathic pain. However, many patients fail to achieve adequate pain relief from these highly brain-penetrant drugs because of dose-limiting central nervous system side effects. Here, we describe the functional properties of trans-N-{[2'-(aminosulfonyl)biphenyl-4-yl]methyl}-N-methyl-N'-[4-(trifluoromethoxy)benzyl]cyclopentane-1,2-dicarboxamide (CDA54), a peripherally acting sodium channel blocker. In whole-cell electrophysiological assays, CDA54 blocked the inactivated states of hNa(V)1.7 and hNa(V)1.8, two channels of the peripheral nervous system implicated in nociceptive transmission, with affinities of 0.25 and 0.18 microM, respectively. CDA54 displayed similar affinities for the tetrodotoxin-resistant Na+ current in small-diameter mouse dorsal root ganglion neurons. Peripheral nerve injury causes spontaneous electrical activity in normally silent sensory neurons. CDA54 inhibited these injury-induced spontaneous action potentials at concentrations 10-fold lower than those required to block normal A- and C-fiber conduction. Consistent with the selective inhibition of injury-induced firing, CDA54 (10 mg/kg p.o.) significantly reduced behavioral signs of neuropathic pain in two nerve injury models, whereas the same dose of CDA54 did not affect acute nociception or motor coordination. In anesthetized dogs, CDA54, at plasma concentrations of 6.7 microM, had no effect on cardiac electrophysiological parameters including conduction. Thus, the peripheral nerve sodium channel blocker CDA54 selectively inhibits sensory nerve signaling associated with neuropathic pain.     

几丁质脱乙酰酶(CDA)的研究进展

从多种真菌可分离纯化得到几丁质脱乙酰酶(CDA),CDA催化水解几丁质分子中的乙酰基生成壳聚糖,CDA与传统的浓碱热化学法生产壳聚糖相比,酶法催化提供了一种脱乙酰位点可控的、几丁质主链不被降解的和对环境友好的反应过程,从而得到优质的壳聚糖或壳寡糖。CDA具有重要的生物物理功能和广阔的潜在应用价值,该综述着重介绍了真菌CDA的研究进展,包括CDA的来源、CDA的生理生化性质、底物特异性、生物学功能和潜在应用价值。     

吉西他滨联合奈达铂治疗的非小细胞肺癌患者血清CDA水平变化及意义

目的：探讨吉西他滨联合奈达铂治疗的非小细胞肺癌（NSCLC）患者血清胞苷脱氨酶（CDA）水平变化及意义。方法：选取2013年3月-2015年4月我院收治的93例NSCLC患者为研究对象。二辛可宁比色测定法检测治疗前后NSCLC患者血清CDA水平。记录治疗后NSCLC患者3年总生存率及无瘤生存率。分析血清CDA水平与NSCLC患者总生存期及无瘤生存期的关系。结果：NSCLS患者治疗前血清CDA及IGF-1水平明显高于吉西他滨联合奈达铂治疗后NSCLC患者血清CDA水平[（7.37±2.04） U·mg^-1 vs（5.33±1.45） U·mg^-1;（346.32±82.76）μg·L^-1 vs（105.84±33.02）μg·L^-1,P<0.05]。相关性分析显示血清CDA与IGF-1呈正相关。吉西他滨联合奈达铂治疗后NSCLC患者1年、2年、3年生存率分别为64.52%（60/93）、41.94%（39/93）、22.58%（21/93）;吉西他滨联合奈达铂治疗后NSCLC患者1年、2年、3年无瘤生存率为56.99%（53/93）、33.33%（31/93）、12.90%（12/93）。死亡组患者血清CDA水平明显高于生存组患者[（5.64±1.43） U·mg^-1 vs（4.27±0.84） U·mg^-1,P<0.05]。Cox单因素及多因素分析显示临床分期、ECOG-PS、淋巴结转移、肿瘤直径、IGF-1、CDA与NSCLC患者总生存期关系密切。Cox单因素及多因素分析显示临床分期、IGF-1及CDA与NSCLC无瘤生存期关系密切。结论：吉西他滨联合奈达铂治疗后NSCLC患者血清CDA、IGF-1水平降低,且血清CDA、IGF-1水平及TNM分期与吉西他滨联合奈达铂治疗的NSCLC患者生存预后密切相关。     

Effects of antiinflammatory drugs on the release from porcine synovial tissue in vitro of interleukin 1 like cartilage degrading activity

The effects were studied of antiinflammatory drugs possessing inhibitory effects on (a) cyclooxygenase (CO), (b) cyclooxygenase plus 5-lipoxygenase (CO-LO), (c) 5-lipoxygenase (5-LO) and (d) phospholipase A2 (PLA2) activities, for their actions on the release from porcine synovial tissue in culture of cartilage-degrading ("catabolin" or interleukin-1 like) activity (= CDA). CDA was reduced by CO inhibitors, enhanced by CO-LO and PLA2 inhibitors, and unaffected by 5-LO inhibitors. These results suggest that (a) antiinflammatory drugs may affect synovial production of CDA ascribable to IL-1, according to their properties as inhibitors of arachidonate metabolism, and (b) products of arachidonic acid metabolism may influence production of synovial CDA.     

The fate of 4-cyanoacetanilide in rats and mice; mechanism of formation of a novel electrophilic metabolite

1. The metabolic fate of 4-cyanoacetanilide (CAA), labelled with 14C and 13C in the N-acetyl group, was studied in rats (oral dose, 22.5 mg/kg) and mice (oral dose 21.7 mg/kg). 2. The metabolic profile in the urine of rats was compared with that obtained previously with 4-cyano-N,N-dimethylaniline (CDA) and confirms the intermediacy of CAA in the metabolism of CDA. 3. The precursor of a major metabolite of CDA and CAA (the mercapturic acid N-acetyl-S-[2-keto-2-(4-cyanoanilino)ethyl]cysteine, metabolite C) was identified in the urine of CAA-dosed rats as the O-sulphate conjugate of N-(4-cyanophenyl)glycolamide. 4. Pretreatment of rats with the sulphotransferase inhibitor pentachlorophenol reduced the yield of the mercapturic acid metabolite C, further indicating the intermediacy of a sulphate conjugate. 5. Metabolite C was not formed from CAA by mice; thus, this species difference, also observed with CDA, occurs at the level side-chain (acetyl) hydroxylation as well as at N-acetylation of 4-cyanoaniline as previously proposed. 6. The significance of this pathway as a bioactivation reaction of CDA, CAA and other acetanilides is discussed.     

Toxic death case in a patient undergoing gemcitabine-based chemotherapy in relation with cytidine deaminase downregulation

Gemcitabine is an antimetabolite drug used in the treatment of various solid tumours, including lung, pancreatic or gynaecological cancers. Innovative combinational strategies (e.g. gemcitabine+capecitabine or gemcitabine+oxaliplatin) make gemcitabine an extensively prescribed drug now. Gemcitabine is characterized by a narrow therapeutic index, and its liver elimination depends upon a key enzymatic step, driven by cytidine deaminase (CDA). CDA is prone to gene polymorphism, including the 208A>G mutation, which can result in marked enzymatic deficiency with subsequent impact on drug exposure levels and related toxicities. We have developed a simple and inexpensive method to determine phenotypically CDA status in cancer patients, as an attempt to detect those at risk upon gemcitabine intake. Conjointly to genotypic investigations, this method was used to phenotype, in a retrospective setting, a female patient displaying extremely severe, and eventually lethal, toxicities after administration of a standard gemcitabine/carboplatin protocol. Phenotypic investigation showed a marked CDA deficiency (-75%) in this patient when compared with a reference, nontoxic population. Genetic studies undertaken next to screen mutations, possibly at the origin of this deficiency, showed heterozygosity for the 79A>C single-point mutation, whereas surprisingly the canonical CDA 208A>G polymorphism was not found. Taken together, this case report demonstrates, for the first time, that CDA downregulation can lead to toxic-death in patients exposed to gemcitabine. Besides, we showed here that our cost-effective and simple phenotypic approach should enable, in the future, the detection of deficient patients at risk upon gemcitabine administration.     

Variantes genéticas y actividad enzimática de la citidin desaminasa: relación con la toxicidad a la capecitabina y recomendación de ajuste de las dosis

ObjectiveCapecitabine, an antineoplastic drug used in the treatment of breast and colon cancer, can cause severe, even fatal toxicity in some patients. The interindividual variability of this toxicity is largely due to genetic variations in target genes and enzymes of metabolism of this drug, such as thymidylate synthase and dihydropyrimidine dehydrogenase. The enzyme cytidine deaminase (CDA), involved in the activation of capecitabine, also has several variants associated with an increased risk of toxicity to treatment, although its role as a biomarker is not yet clearly defined.Therefore, our main objective is to study the association between the presence of genetic variants in CDA gen, CDA enzymatic activity and the development of severe toxicity in patients treated with capecitabine whose initial dose was adjusted based on the genetic profile of the dihydropyrimidine dehydrogenase gen (DPYD).MethodProspective multicenter observational cohort study, focused on the analysis of the genotype-phenotype association of the CDA enzyme.After the experimental phase, an algorithm will be developed to determine the dose adjustment needed to reduce the risk of treatment toxicity according to CDA genotype, developing a clinical guide for capecitabine dosing according to genetic variants in DPYD and CDA. Based on this guide, a Bioinformatics Tool will be created to generate the pharmacotherapeutic report automatically, facilitating the implementation of pharmacogenetic advice in clinical practice. This tool will be a great support in making pharmacotherapeutic decisions based on the patient's genetic profile, incorporating precision medicine into clinical routine. Once the usefulness of this tool has been validated, it will be offered free of charge to facilitate the implementation of pharmacogenetics in hospital centers and equitably benefit all patients on capecitabine treatment.     

The fate of 4-cyano-N,N-dimethylaniline in rats; a novel involvement of glutathione in the metabolism of anilines

4-Cyano-N,N-dimethylaniline (CDA), when administered to rats as a single oral dose (18.5 mg/kg), was rapidly absorbed and eliminated as a mixture of metabolites in the urine (86% dose after 24 h). Residues in tissues after 48 h, expressed as microgram equiv. of CDA, were: liver, 0.35; kidney, 0.28; testes, 0.08; fat, 0.06; bone marrow, 0.15 and blood, 0.32. Absorption, metabolism and elimination following four consecutive daily doses of CDA (65 mg/kg) were similar to those at the lower dose. The major metabolite was 2-amino-5-cyanophenyl sulphate with its mono- and di-N-methyl analogues as minor metabolites. 4-Cyanoaniline, its N-acetyl derivative and an unstable derivative were also found as metabolites. Three sulphur-containing metabolites with methylsulphinyl-, methylsulphonyl-, and N-acetylcysteinyl-groups attached to the C2 atom of an N-acetyl group were identified, the latter accounting for 10.3% and 4.1% of the low and high doses, respectively. The sulphur-containing metabolites indicate the involvement of glutathione in metabolism at the N-acetyl group. This implies the generation of an electrophilic intermediate, possibly the sulphate conjugate of an N-glycolylaniline, in the metabolism of CDA.     

The fate of 4-cyano-N,N-dimethylaniline in mice: the occurrence of a novel metabolite during N-demethylation of an aromatic amine

4-Cyano-N,N-dimethylaniline (CDA), when administered as a single oral dose to mice (18.5 mg/kg), was rapidly absorbed and eliminated. The major route of elimination was the urine (78% dose in 24h). The residues in the tissues 48 h after dosing, as microgram equiv. of CDA/g, were: liver, 0.19; kidney, 0.10; testes, 0.01; fat, 0.10; blood, 0.02. The major metabolite was 2-amino-5-cyanophenyl sulphate, with the N-methyl analogue as a minor metabolite. A novel metabolite, N-acetyl-S-(4-cyanoanilinomethyl)cysteine, was also a significant urinary metabolite, indicating that an electrophilic intermediate is generated during the N-demethylation of CDA. The implications are that N-demethylation may have important toxicological consequences.