医用合成可降解生物材料的新进展

本文主要综述近五年来研究和应用较多的合成可降解聚合物材料。主要包括聚原酸酯、聚酸酐、聚ε－己内酯、聚三甲基碳酸酯、聚氨基酸、聚乙醇酸及聚乳酸等化学合成类可降解材料研究和应用的新进展。     

医用合成可降解生物材料的新进展

本主要综述近五年来研究和应用较多的合成可降解聚合物材料。主要包括聚原酸酯、聚酸酐、聚ε－己内酯、聚三甲基碳酸酯、聚氨基酸、聚乙醇酸及聚乳酸等化学合成类可降解材料研究和应用的新进展。     

Ⅰ型胶原修饰聚乳酸聚乙醇酸微球支架上骨髓间充质干细胞的黏附和成骨分化

背景：组织工程骨成骨功能终末细胞需要骨髓间充质干细胞在体外加以诱导或在体内以基因转染等技术加以诱导。 目的：研究Ⅰ型胶原修饰的聚乳酸聚乙醇酸微球支架上骨髓间充质干细胞黏附和成骨分化的能力。 方法：制备聚乳酸聚乙醇酸微球支架,分离纯化雌性SD大鼠骨髓间充质干细胞。将培养至第3代骨髓间充质干细胞与未经处理的聚乳酸聚乙醇酸微球及Ⅰ型胶原修饰的聚乳酸聚乙醇酸微球共同培养14 d,观察细胞在不同支架表面的黏附生长。 结果：扫描电镜及FDA-PI染色发现,骨髓间充质干细胞可在聚乳酸聚乙醇酸微球支架上生长,而与未修饰的聚乳酸聚乙醇酸微球相比骨髓间充质干细胞更容易在Ⅰ型胶原修饰的聚乳酸聚乙醇酸微球上黏附增殖。Ⅰ型胶原修饰的聚乳酸聚乙醇酸微球有利于骨髓间充质干细胞的黏附、增殖,并且有一定诱导干细胞成骨分化的能力。     

静电纺丝聚乳酸复合物纳米纤维材料与小鼠神经干细胞的生物相容性

背景:聚乳酸聚乙醇酸支架材料广泛应用于组织工程学领域,但其细胞黏附性较差、缺乏活性功能基团以及疏水性较强等缺点限制了其进一步的发展和应用。目的:观察小鼠神经干细胞与静电纺丝聚乳酸聚乙醇酸/聚乙二醇共聚物纳米纤维支架材料的体外相容性。方法:自孕15 d CD-1小鼠胚胎大脑皮质分离培养小鼠神经干细胞。静电纺丝法制备聚乳酸聚乙醇酸和聚乳酸聚乙醇酸/聚乙二醇纳米纤维支架材料,扫描电镜观察材料结构;取第5代神经干细胞分别接种于聚乳酸聚乙醇酸和静电纺丝聚乳酸聚乙醇酸/聚乙二醇纳米纤维支架材料上,进行体外培养。结果与结论:扫描电镜检测显示,两种支架材料呈现相互交联的多孔网状结构。聚乳酸聚乙醇酸组和静电纺丝聚乳酸聚乙醇酸/聚乙二醇组纤维直径和孔隙率差异无显著性意义(P0.05)。CCK-8检测显示,两种材料无明显细胞毒性。神经干细胞在支架材料中生长良好,两组吸光度值均随培养时间延长而增大,两组在培养1,3,5,7,9,11 d吸光度值差异均有显著性意义(P0.05)。两组材料培养3,6,9 h,静电纺丝聚乳酸聚乙醇酸/聚乙二醇组的细胞黏附率明显高于聚乳酸聚乙醇酸组(P0.05)。Hoechst染色显示两组细胞核质均染,形态正常,静电纺丝聚乳酸聚乙醇酸/聚乙二醇组细胞数量明显多于聚乳酸聚乙醇酸组(P0.05)。扫描电镜观察显示,与聚乳酸聚乙醇酸组相比,静电纺丝聚乳酸聚乙醇酸/聚乙二醇组神经干细胞在支架上的生长情况和基质分泌更好。结果说明,静电纺丝法制备的静电纺丝聚乳酸聚乙醇酸/聚乙二醇纳米纤维支架细胞生物相容性良好,安全无毒,具备合适的孔径和孔隙率,适宜神经干细胞生长,是一种适用于组织工程优质的支架载体。     

生物可降解材料在医学领域的应用

生物可降解材料包括天然可降解材料和人工合成可降解材料,由它们制成的产品应用于人体后可逐渐被降解吸收.本文综述了部分已应用于临床的生物可降解材料的特性、种类和应用现状,其中包括甲壳素、胶原蛋白、细菌纤维素、聚羟基丁酸酯、聚乳酸、聚乙醇酸、聚对二氧环己酮和聚丁二酸丁二醇酯及磷酸钙,并对相关的需要解决的问题进行了讨论.总之生物可降解材料所具有的理化结构和降解特性决定其运用于医用产品将会发挥有益的治疗作用,尽管目前只在有限范围应用,在实际应用时也存在一些问题,但生物可降解材料将会有广阔的应用前景.     

载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒抑制人肝癌细胞HepG2的作用

背景：临床上应用的紫杉醇注射剂毒性大,过敏反应发生率高。 目的：研制载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒,观察其对人肝癌细胞HepG2的抑制及诱导细胞凋亡的作用。 方法：采用MTT法检测0,3.125,6.25,12.5,25,50,100 mg/L载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒子或紫杉醇作用后人肝癌细胞HepG2的生长;观察25 mg/L载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒子或紫杉醇作用后人肝癌细胞HepG2的形态变化,并观察0,12.5,25,50 mg/L载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒子作用后细胞的凋亡情况。 结果与结论：在3.125-100 mg/L质量浓度范围内,载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒子与紫杉醇均能明显抑制HepG2细胞的生长,且载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒子显示出明显的缓释作用,随着作用时间的增加其抑制率显著增加,72 h时抑制效果最好,但紫杉醇此现象不明显。载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒子或紫杉醇作用后,细胞出现典型的凋亡形态,且随着载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒子作用时间的增加这一现象更加典型;12.5,25,50 mg/L载紫杉醇聚乳酸聚乙醇酸共聚物纳米粒子可明显诱导细胞凋亡,且有明显的量效和时效关系,质量浓度越高、时间越长效果越明显。     

聚原酸酯抗癌药物毫微囊的制备及体外释药研究

采用Ｗ／Ｏ／Ｗ型复乳制备聚原酸酯载甲氨喋呤（ＭＴＸ）毫微囊微球,通过多种条件实验,制备了聚原酸酯载药毫微囊,并对药物体外释放动力学进行研究。结果表明有机溶剂组成、内部水相药物浓度、溶剂挥发温度等均对毫微囊的结构与性能产生影响,经优化所制备毫微囊粒径在５００～８００ｎｍ之间,药物包封率高。     

壳聚糖海绵体的不同制备方法对人胎儿皮肤 成纤维细胞相容性的影响

1　前　言组织工程是当今生物医学领域最活跃的研究领域之一,其中重要的一个方面是通过细胞在生物降解材料构成的三维支架中培养以制备生物活性人工器官。生物降解材料的选择与成孔加工,对一项具体研究的成败起着关键作用。目前组织工程采用的支架材料有聚乙醇酸或聚乙丙交酯[1]、胶原蛋白[2]、胶原/粘多糖复合物[3]等。研究发现,聚乙醇酸或聚乙丙交酯用作支架材料,有时会造成非细菌性炎症,原因在于酸性降解产物的局部积蓄。来自动物的胶原存在免疫原性、病毒疾病的传染、降解速度过快等缺点,而且成本较高。壳聚糖及其衍生物来源丰富,成本低…     

新型骨材料填充器的研制及其生物相容性研究*

目的探讨采用聚对苯二甲酸乙二醇酯（PET）为基质的新型骨材料填充器的研制及其生物相容性。方法将聚对苯二甲酸乙二醇酯制成网孔状的填充料袋,结合输送器械,获得可膨胀性的骨材料扩张及填充系统。按照GB／T16886标准通过急性全身毒性试验、溶血试验和致敏试验系统评价聚对苯二甲酸乙二醇酯注射聚甲基丙烯酸甲脂（PMMA）复合材料（PET／PMMA）的生物相容性。结果PET／PMMA复合材料急性毒性试验实验组及阴性对照组小鼠活动、体重及呼吸均无明显差异;致敏豚鼠试验组无红斑及水肿;溶血率为1．24％,无溶血性。结论本课题组研制的新型骨材料填充器,经检验其具有良好的生物相容性。     

纤维蛋白胶复合重组人骨形态发生蛋白2微球对犬骨髓基质细胞增殖与分化的影响

背景：前期实验证实聚乳酸-聚乙醇酸微球/纤维蛋白胶能作为重组人骨形态发生蛋白2的良好可注射性缓释载体。 目的：观察可注射性骨形态发生蛋白缓释体系对犬骨髓基质细胞增殖与分化的影响。 方法：采用复乳-溶剂挥发法制备重组人骨形态发生蛋白2/聚乳酸-聚乙醇酸共聚物载药微球,然后将微球与纤维蛋白胶复合制备出重组人骨形态发生蛋白2/聚乳酸-聚乙醇酸共聚物/纤维蛋白胶复合材料,采用细胞培养及组织化学等方法观察微球对犬骨髓基质细胞的增殖与分化的影响。 结果与结论：重组人骨形态发生蛋白2/聚乳酸-聚乙醇酸共聚物/纤维蛋白胶微球对骨髓基质细胞的增殖无明显影响,但对细胞的分化功能有明显的促进作用。说明纤维蛋白胶复合重组人骨形态发生蛋白2微球能够提高骨髓基质细胞的体外成骨能力,可作为骨形态发生蛋白的良好载体。     

Fatty acids modulate excitability in guinea-pig hippocampal slices.

A variety of fatty acids produced sustained changes in excitability in the guinea-pig hippocampal slice. Although each fatty acid was unique, a general pattern was evident. During a 30-min exposure, the synaptic potential was minimally affected, although population spike amplitude showed significant increases. With wash, synaptic efficacy increased. The increase in the synaptic potential was significant with arachidonic acid (100 microM), oleic acid (100 microM), myristic acid (250 microM) and capric acid (250 microM). Also with wash, the coupling between the synaptic potential and the population spike was reduced significantly for most of the fatty acids tested: arachidonic acid (50 microM, 100 microM), linoleic acid (100 microM) oleic acid (100 microM), stearic acid (100 microM), myristic acid (250 microM) and capric acid (250 microM, 500 microM). The fatty acids may influence neuronal excitability, in part, through a direct membrane action. The observed synaptic enhancement is consistent with a role for a fatty acid in long-term potentiation. In addition, fatty acid exposure mimics the effects of X-radiation. We suggest that free radical-induced release of fatty acids contributes to electrophysiological damage in a number of pathological states.     

乙酸消融胆道的实验研究

目的探讨乙酸消融家兔胆道后病理及肝功改变,为临床应用消融栓塞胆道治疗肝内胆管结石提供实验依据。方法观察家兔右外叶胆道于25%至5%浓度乙酸消融后肝脏功能状态、肝组织病理改变和术后存活情况。结果25%乙酸胆道消融造成右外叶肝脏大块坏死,仅肝叶边缘有少量存活肝组织。20%乙酸胆道消融后近肝门部肝实质以汇管区为中心的坏死,肝叶中部见汇管区及周围少量肝细胞坏死,肝叶边缘见汇管区点状坏死。15%乙酸胆道消融后近肝门部见汇管区及周围少量组织坏死,肝叶中部及边缘组织见胆管无明显改变,周围组织点状坏死。10%乙酸胆道消融后近肝门部汇管区胆管坏死,周围充血,肝叶中部胆管上皮完整,周围组织充血,肝叶边缘胆管完整,周围少量肝细胞肿胀。5%乙酸胆道消融后近肝门部胆管上皮坏死,肝叶中部胆管上皮完整,仅充血或少量肝细胞肿胀。结论20%为乙酸消融胆道较理想的浓度。     

血尿酸与糖尿病肾病患者肾脏功能减退的相关性分析

目的探讨尿酸与糖尿病肾病(diabetic nephropathy,DN)患者肾脏功能减退的相关性。方法纳入670例就诊于四川大学华西医院,并且诊断为糖尿病肾病的患者为研究对象,记录其年龄、性别,检测尿酸(uric acid,UA)、肌酐(creatinine,CREA)、三酰甘油(triglyceride,TG)、总胆固醇(total cholesterol,TC)、高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C)、低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL-C)、尿素(urea,UREA)和糖化血红蛋白(glycated hemoglobin,HbA1c)水平。根据尿酸水平分为高尿酸血症组和正常尿酸组。对各检测指标进行组间比较,并进行相关性分析,分析尿酸与糖尿病肾病患者肾脏进展的相关性。结果研究人群中,高尿酸组有334例,正常尿酸组有336例。高尿酸组的肌酐、尿素高于正常尿酸组,肾小球滤过率和糖化血红蛋白低于正常尿酸组,差异有统计学意义(P<0.05);尿酸水平与糖尿病肾病患者的肾小球滤过率成负相关(P<0.05)。结论糖尿病肾病患者的尿酸水平与eGFR水平成负相关,即尿酸水平越高,肾脏功能越差。糖尿病肾病患者的日常管理中,应重视尿酸水平的检测。     

Effects of dietary fatty acids on the early stages of neoplastic induction in the rat pancreas. Changes in fatty acid composition and development of atypical acinar cell nodules.

Diets enriched with fat, especially unsaturated fat, promote experimental pancreatic carcinogenesis, but little is known of the effects of individual fatty acids. The effect of stearic and oleic acid on pancreatic fatty acids and atypical acinar cell nodules (preneoplastic lesions) was studied in 14-day-old weanling male Leeds strain rats (n = 60) given the carcinogen azaserine. Rats were allocated to one of six groups: untreated controls (n = 10), 20% stearic acid diet (n = 10), 20% oleic acid diet (n = 10), carcinogen alone (n = 10), carcinogen plus 20% stearic acid diet (n = 10) or carcinogen plus 20% oleic acid diet (n = 10). Azaserine was administered by intraperitoneal injection in a dose of 30 mg/kg at 2, 3 and 4 weeks of age. When total lipid extracts of pancreas were examined, there was an increase in stearic acid in the stearic acid fed group and an increase in oleic acid in the oleic acid fed group, irrespective of carcinogen treatment. The relative content of all other pancreatic fatty acids was suppressed by feeding oleic acid. At 26 weeks, the number and volumetric indices of pancreatic atypical acinar cell nodules was increased only in rats given azaserine and oleic acid. The enhancing effect of oleic acid on pancreatic carcinogenesis may be associated with pancreatic fatty acid changes.     

Low-molecular-weight copolymers composed of L-lactic acid and various DL-hydroxy acids as biodegradable carriers

Biodegradable copolymers of L -lactic acid (L -LA) and DL -α-hydroxy acids with relatively low molecular weights, for example L -LA/DL -lactic acid (DL -LA), L -LA/DL -α-hydroxybutyric acid (DL -HBA), L -LA/DL -α-hydroxyisovaleric acid (DL -HIVA), and L -LA/DL -α-hydroxyisocaproic acid (DL -HICA), were synthesized by quantitative direct copolycondensation without catalysts at 200°C. The in vitro degradation, which was evaluated by measuring the weight loss of these copolymers in M/15 phosphate buffer solution (pH 7,2) without enzymes at 37°C, is strongly dependent on the kind and molecular weight of these copolymers, resulting in the formation of different degradation patterns such as parabola type (L -LA/DL -HBA system), linear type (L -LA/DL -LA system), and S type (L -LA/DL -HIVA and L -LA/DL -HICA systems).     

尿素酶预处理-气相色谱-质谱法诊断琥珀酸半醛脱氢酶缺陷病

本文探讨琥珀酸半醛脱氢酶(succinic semialdehyde dehydrogenase，SSADH)缺陷病各尿液标志物的气相色谱-质谱法(Gas Chromatography-Mass Spectrometry，GC-MS)分析特征。收集SSADH患儿的尿液标本，经去尿素、加内标(正十七酸)、除蛋白、真空干燥处理，残余物进行三甲基硅烷化衍生后进样行GC-MS法分析。尿液中可检测到明显的4-羟基丁酸、2，4-二羟基丁酸、3，4-二羟基丁酸和4，5-二羟基己酸信号。在TIC图上，其绝对保留时间(相对保留时间)分别是6．32min(0．434)，7．80min(0．536)，7．94min(0．546)，8．80min，8．90min(0．605，0．612)。在质谱图上，其特征离子(m／z，TMS)分别是M-15(233，2)，M-15(321，3)，M-15(321，3)，M-15(349，3)。GC-MS法分离鉴定尿液代谢成分，可作为诊断该病的一种可靠手段。     

Conformational studies on polypeptides containing L-alanine and ω-amino acids

The synthesis and the conformational studies of the following sequential polypeptides are reported: poly(alanyl-3-aminopropanoic acid), poly(alanyl-4-aminobutanoic acid), poly(alanyl-5-aminopentanoic acid), and poly(alanyl-6-aminohexanoic acid). These compounds were examined in the solid state by X-ray diffraction and in solution by circular dichroism spectroscopy. X-ray diffraction patterns indicate that all copolymers assume an antiparallel pleated-sheet conformation. The results in solution suggest that the synthetic polypeptides, in 2,2,2-trifluoroethanol (TFE)/methanol exhibit a β-conformation. The addition of water to a solution of copolymers in TFE destabilize this ordered structure except in the case of poly(alanyl-6-aminohexanoic acid).     

Inhibition of GABAA receptor (GABAR) currents by arachidonic acid in HEK 293 cells stably transfected with α1β2γ2 GABAR subunits

Agonist-stimulated liberation of arachidonic acid and subsequent generation of active metabolites are established components of several signal transduction pathways including pathways that regulate ion channels. We evaluated the role of arachidonic acid and some related unsaturated and saturated fatty acids in the modulation of a stably expressed recombinant gamma-aminobutyric acidA receptor (GABAR) isoform, the alpha1beta2gamma2 isoform. Whole-cell currents evoked by 10 microM GABA were inhibited in a concentration-dependent manner by arachidonic acid (0.1-100 microM). This effect of arachidonic acid to inhibit GABAR currents was not reproduced by the non-metabolizable analog of arachidonic acid, 5,8,11,14-eicosatetraynoic acid (ETYA) or by other monounsaturated or saturated fatty acids. However, another polyunsaturated fatty acid, linoleic acid, which is an essential fatty acid and an effective reductant like arachidonic acid, inhibited GABAR currents in a manner similar to arachidonic acid. Nordihydroguaiaretic acid (NDGA), indomethacin and 1-amonibenzotriazole (1-ABT) did not block the inhibitory effect of arachidonic acid, suggesting that arachidonic acid metabolites of the lipoxygenase, cyclooxygenase or P-450 pathways are unlikely to play a major role in the inhibitory effect of arachidonic acid on GABAR currents. However, the antioxidant N-acetyl cysteine (NAC), a scavenger of active oxygen radicals, reduced the inhibitory effect of arachidonic acid on GABAR currents significantly (P<0.01), suggesting that active oxygen radicals might mediate inhibition of GABAR currents by arachidonic acid.     

Catabolism of L-phenylalanine and L-tyrosine by Rhodobacter sphaeroides OU5 occurs through 3,4-dihydroxyphenylalanine

Rhodobacter sphaeroides OU5 utilized l-phenylalanine as sole source of nitrogen for growth. The metabolites of l-phenylalanine catabolism, i.e. 4-hydroxy phenylalanine (l-tyrosine), 3,4-dihydroxyphenylalanine (DOPA), 3,4-dihydroxyphenyl-pyruvic acid (DOPP), 3,4-dihydroxyphenyllactic acid (DOPLA), 3,4-dihydroxyphenyl-acetic acid (DOPAc) and 3,4-dihydroxybenzoic acid (PC), were identified using liquid chromatography-mass spectroscopy (LC-MS). With 2-oxoglutarate as an amino acceptor, DOPA aminotransferase activity was observed with cell-free extracts and the product DOPP was confirmed through mass analysis. Reductive deamination of DOPA also occurred in the absence of 2-oxoglutarate, whose products were 3,4-dihydroxyphenylpropionic acid (DPPA) and ammonia. The enzyme DOPA-reductive deaminase (DOPARDA) was purified to its homogeneity and characterized. DOPARDA has an obligate requirement for NADH and is functional at low concentrations of the substrate (<150 microM). The molecular mass of the purified enzyme was approximately 274kD and the enzyme could be a heterotetramer of 110, 82, 43 and 39kD subunits as determined by SDS-PAGE.     

大鼠脑缺血再灌注损伤期间脑组织间质各种氨基酸递质水平的变化

目的: 研究清醒大鼠脑缺血再灌注损伤期间海马、纹状体和新皮质细胞外多种氨基酸递质水平的变化。方法: 复制清醒大鼠前脑缺血模型,利用微透析技术,于缺血前、缺血15 min、再灌注15 min、30 min、60 min、120 min及180 min时所收集透析液,测定谷氨酸、天门冬氨酸、γ-氨基丁酸、甘氨酸、牛磺酸、丙氨酸、谷氨酰胺、丝氨酸、苏氨酸等9种氨基酸含量;并计算缺血再灌注期间不同脑区兴奋毒性指数(EI)的变化。结果: 缺血期间细胞外液中不仅兴奋性氨基酸如谷氨酸、天门冬氨酸等以及兴奋性氨基酸受体调质如甘氨酸显著增高,而且抑制性氨基酸如γ-氨基丁酸及抑制性氨基酸受体调质如牛磺酸和丙氨酸亦明显升高;但是反映兴奋性神经递质与抑制性神经递质平衡综合指数的EI值在缺血期间明显升高。结论: 脑缺血期间单纯谷氨酸、天门冬氨酸等升高可能不足以造成缺血性损伤,其它神经递质或其它因素协同兴奋性氨基酸在介导神经细胞内一系列病理生化反应而引起延迟性神经细胞损伤的过程中可能起重要作用。