聚乳酸/壳聚糖纤维复合支架的制备与性能

背景:聚乳酸/壳聚糖纤维复合支架材料既可提高支架的力学性能,又可中和聚乳酸的酸性降解产物,提高生物相容性,从而满足组织工程支架的要求。目的:制备用于组织工程的聚乳酸/壳聚糖纤维复合支架。方法:采用热致相分离法制备了聚乳酸/壳聚糖纤维复合支架。测定了复合支架的微观形貌、孔隙率、压缩模量、降解特性、蛋白质吸附特性。结果与结论:复合支架具有纳米微米共存的亚微观结构。在聚乳酸纳米纤维网络中引入壳聚糖纤维,有效地增强了复合支架的压缩模量和蛋白质吸附能力,复合支架压缩模量为纯聚乳酸纳米支架的3.75倍,蛋白质吸附能力比纯聚乳酸纳米支架提高了112%。体外降解实验表明复合支架降解液的pH值随时间的下降明显变缓。提示,在聚乳酸纳米纤维网络中引入壳聚糖纤维,可有效增强支架的压缩模量,提高蛋白质吸附能力,并可有效减缓聚乳酸降解过程中pH值的下降,克服酸性产物引发的无痛性炎症问题。     

基于琼脂糖/壳聚糖共混凝胶模型的壳聚糖生物相容性的机理研究

目的 以琼脂糖/壳聚糖共混凝胶为模型,研究壳聚糖材料生物相容性的可能机理.方法 通过共混法,制备出一系列不同壳聚糖含量的琼脂糖/壳聚糖共混凝胶.利用傅里叶变换红外光谱(FTIR)分析共混凝胶的化学基团,利用荧光素-4-异硫氰酸酯(FITC)标记法观察琼脂糖和壳聚糖之间的可共混性.通过Zeta电势测量共混凝胶的电荷,利用二喹啉甲酸(BCA)法分别测定胎牛血清(FBS)总蛋白和牛血清白蛋白(RSA)在共混凝胶上的吸附,利用酶联免疫吸附(ELISA)法测定纤黏连蛋白(FN)在共混凝胶上的吸附.细胞实验以人微血管内皮细胞系(HMEC-1)为模型,通过观测细胞的黏附、增殖和形态来评价共混凝胶的细胞相容性.结果 琼脂糖/壳聚糖共混凝胶含有壳聚糖特征性的化学基团.琼脂糖和壳聚糖之间存在着良好的可共混性,壳聚糖的氨基基团在共混凝胶中呈均匀分布.在pH酸性条件下(pH 3.0)共混凝胶带有较强的正电荷,然而在pH中性条件下(pH 7.4)所有共混凝胶的Zeta电势均降低至0 mV附近.各组共混凝胶之间对FBS总蛋白以及BSA的吸附差异无统计学意义,但是共混凝胶对FN的吸附却随着壳聚糖含量的升高而显著升高.细胞实验结果显示:随着壳聚糖含量的提高,共混凝胶的细胞相容性有明显改善,HMECs在壳聚糖含量较高的凝胶上表现出良好的黏附、铺展和增殖.结论 相对于血清中的其他蛋白,壳聚糖组分对FN存在优先吸附,从而能够促进细胞在共混凝胶表面的黏附铺展.与传统观点不同,本研究发现壳聚糖的生物相容性与其所携带的正电荷无关.     

等离子体表面改性涤纶材料的血浆蛋白吸附与血小板黏附行为研究

采用等离子体表面接枝改性技术在涤纶 (聚对苯二甲酸乙二醇酯 ,PET)材料表面接枝不同分子量的聚乙二醇 (PEG) ,从表面能与界面自由能的角度分析了血浆蛋白 (纤维蛋白原和白蛋白 )在材料表面的竞争吸附关系 ,结果表明接枝了 PEG长链分子的 PET材料具有优先吸附白蛋白的性质 ,其中接枝 PEG6 0 0 0的 PET优先吸附倾向最明显。预接触白蛋白和纤维蛋白原的 PET材料表面的血小板黏附实验表明 :吸附白蛋白的表面能够显著抑制血小板的黏附和聚集 ,表现出好的血液相容性 ,而吸附了纤维蛋白原的材料表面具有降低血液相容性的性质。     

磺化聚醚砜对光敏剂-亚甲蓝的吸附去除研究Ⅱ.磺化聚醚砜对血浆中亚甲蓝的吸附去除研究

研究了磺化聚醚砜吸附柱对血浆中亚甲蓝的吸附效果,并检测了流经吸附柱的牛血清白蛋白随时间变化的规律以及过柱前后血浆中主要生化指标的变化情况.结果:磺化聚醚砜对亚甲蓝的吸附效果明显优于聚醚砜对亚甲蓝的吸附效果;其对白蛋白的吸附较小;对血浆中主要生化指标的影响可以忽略不计.     

氢氧化铝佐剂对重组大肠杆菌表达的戊型肝炎239抗原的吸附研究

目的:探索氢氧化铝佐剂对重组大肠杆菌表达的戊型肝炎239抗原(HEV239)的吸附力种类以及在戊肝疫苗制备研究中的应用。方法:用兰格缪尔吸附方程计算在不同浓度氯化钠(NaCl)或乙二烯乙二醇(EG)条件下,HEV239在氢氧化铝佐剂表面的最大吸附量(Γm),根据Γm随NaCl或EG浓度变化趋势判断吸附作用力的种类。配制添加多羟基化合物且含不同浓度磷酸盐的试验疫苗,计算Γm并绘制其随磷浓度变化的曲线。ELISA法定量检测并计算含不同浓度磷的试验疫苗与羊淋巴液作用12h后抗原的吸附率。结果:HEV239的Γm随离子强度(NaCl浓度)或疏水物质浓度(EG体积)增加而降低,也随磷酸盐浓度增加而降低。疫苗在羊淋巴液中的抗原吸附率随磷酸盐浓度增加而降低,最终达到稳定水平。结论:HEV239在氢氧化铝佐剂表面的吸附受到静电引力和疏水作用力的双重影响。利用此机理向疫苗中添加磷酸盐和多羟基化合物可降低疫苗抗原在制剂中的吸附量和在羊淋巴液中的吸附率。     

聚乳酸/壳聚糖纳米纤维/纳米羟基磷灰石支架与兔软骨细胞的相容性

背景：传统的支架材料存在疏水性强,材料表面缺乏细胞表面受体特异结合的生物活性分子,材料的酸性降解产物易引发无菌性炎性反应等不足。根据仿生原理及软骨真实结构和构成来选择和制备组织工程软骨支架能够获得理想效果。 目的：制备聚乳酸/壳聚糖纳米纤维/纳米羟基磷灰石支架,评价其与兔膝关节软骨细胞的生物相容性,探讨其应用于关节软骨组织工程的可行性。 方法：采用二次相分离技术制备聚乳酸/壳聚糖纳米纤维/纳米羟基磷灰石复合支架,将第3代新西兰兔软骨细胞接种至复合支架材料上复合培养,倒置相差显微镜下观察细胞生长情况。细胞-支架复合物在24孔板中培养5 d以后,将其植入裸鼠皮下8周。 结果与结论：聚乳酸/壳聚糖纳米纤维/纳米羟基磷灰石支架材料经化学合成后,具有合适的三维多孔结构,孔隙率为90%,孔径300~450 μm;植入裸鼠皮下8周后Ⅱ型胶原免疫组织化学染色和甲苯胺蓝染色显示细胞-支架复合物中的软骨细胞可以像天然软骨一样分泌黏多糖和Ⅱ型胶原。提示生物材料聚乳酸/壳聚糖纳米纤维/纳米羟基磷灰石对于兔软骨细胞有良好的生物相容性,可作为生物组织工程支架。     

胶原改良聚乳酸电纺丝支架用于组织工程化输尿管的体外构建***

背景：聚乳酸是一种应用广泛的细胞支架材料,但其疏水性和缺乏细胞识别信号影响了在组织工程器官构建中的应用。 目的：探讨Ⅰ型胶原蛋白改良聚乳酸电纺丝支架体外构建组织工程化输尿管的可行性。 方法：用Ⅰ型胶原蛋白醋酸溶液冻干法处理聚乳酸电纺丝,使Ⅰ型胶原蛋白吸附于电纺丝纤维表面,制成胶原改良电纺丝支架。将分离培养的输尿管上皮细胞分别接种于改良聚乳酸电纺丝支架和未处理的聚乳酸电纺丝支架上。 结果与结论：MTT检测显示输尿管上皮细胞在改良支架中生长良好,细胞整体活性在各时间点均明显优于未处理的聚乳酸电纺丝支架上的细胞。扫描电镜观察发现细胞在改良支架表面黏附良好,接种后5 d,支架表面大部分已被增殖的输尿管上皮细胞覆盖。说明胶原改良聚乳酸电纺丝支架能明显提高种子细胞的黏附和增殖活性,可用于体外构建组织工程化输尿管。 关键词：输尿管;电纺丝;聚乳酸;胶原;黏附;增殖;组织工程 doi:10.3969/j.issn.1673-8225.2012.12.002     

生物型抗菌盆底修复材料的制备与性能

背景:哺乳动物细胞外基质组成的生物型修复材料,在盆底组织修复及功能重建方面表现出较大潜力,但细菌感染对生物型修复材料的功能破坏是其中的一个较大问题。目的:制备具备抗菌功能的生物型盆底修复材料。方法:以壳聚糖为基质材料,通过静电吸附和自凝聚纳米粒制备技术获得包载有不同质量浓度替加环素(25,50,100 g/L)的壳聚糖大分子纳米粒混合液,再通过表面涂层技术将其涂覆于细胞外基质材料表面,制得抗菌细胞外基质材料。结果与结论:红外光谱显示,抗菌细胞外基质材料出现壳聚糖的典型糖环骨架振动峰,并且在3 359 cm-1左右峰明显增宽,表明抗菌剂复合涂层修饰成功,由于替加环素的用量非常小,其红外图谱中未能显示其特征吸收峰。扫描电镜观察显示,抗菌细胞外基质材料保存了细胞外基质材料多层排列有序纤维丝构成的主体结构,并且在微丝表面和微丝之间还明显附着一层蓬松鳞片状涂层物质,材料微表面三维孔洞变小,但仍维持多孔连通特性。抑菌圈实验显示,抗菌细胞外基质材料对大肠杆菌和金黄色葡萄球菌具有良好的抗菌性能,并且随着抗菌剂浓度的增大,抑菌圈直径显著增加。     

层层静电自组装表面修饰静电纺丝人工血管的生物相容性研究

背景大、中口径人工血管已成功用于临床,但是由于材料的疏水性小口径人工血管仍不能满足临床的需要。因此,提高人工血管材料的亲水性、抗凝血性一直是医学界研究的热点。目的研究静电自组装修饰后的电纺丝纤维膜的形貌特征、细胞相容性和组织相容性。方法利用静电自组装技术将壳聚糖和肝素修饰到静电纺丝聚乳酸纤维膜表面,通过扫描电镜观察组装前后电纺丝纤维的形貌特征;将人脐静脉内皮细胞种植与组装前后的纤维膜上,通过MTT测试检测细胞增殖能力;通过将组装前后不同材料植入兔皮下15天,通过HE染色检测其组织相容性。结果 SEM结果显示,成功将壳聚糖/肝素组装到电纺丝纤维膜表面。MTT结果显示组装后的电纺丝纤维膜促进HUVEC的增殖。兔皮下植入实验结果显示组装修饰后的电纺丝膜具有良好的组织相容性。结论静电自组装成功应用于静电纺丝中,并且电纺丝纤维膜经修饰后成功提高材料的细胞相容性和组织相容性。     

蛋白质在生物材料表面吸附过程的研究进展

在生物材料的相容性研究中,蛋白质与材料表面的相互作用极其关键,一直是研究的重点之一.一般认为血细胞是与吸附在材料表面的蛋白质分子层相互作用,而不是与材料表面直接接触,因此蛋白质对于细胞的调控和诱导起到了关键作用.探索控制蛋白吸附行为的分子机制,从而调控细胞的应答为设计生物材料提供了思路.综述了蛋白质与生物材料相互作用的研究进展,展望了未来的研究方向.     

Improved bronchodilation with levalbuterol compared with racemic albuterol in patients with asthma

Background: Racemic albuterol is an equal mixture of (R)-albuterol (levalbuterol), which is responsible for the bronchodilator effect, and (S)-albuterol, which provides no benefit and may be detrimental. Objective: We sought to compare 2 doses of a single enantiomer, levalbuterol (0.63 mg and 1.25 mg), and equivalent amounts of levalbuterol administered as racemic albuterol with placebo in patients with moderate-to-severe asthma. Methods: This was a randomized, double-blind, parallel-group trial. Three hundred sixty-two patients 12 years of age or older were treated with study drug administered by means of nebulization 3 times daily for 28 days. The primary endpoint was peak change in FEV₁ after 4 weeks. Results: The change in peak FEV₁ response to the first dose in the combined levalbuterol group was significantly greater compared with the combined racemic albuterol group (0.92 and 0.82 L, respectively; P = .03), with similar but nonsignificant results after 4 weeks (0.84 and 0.74 L, respectively). Improvement in FEV₁ was similar for levalbuterol 0.63 mg and racemic albuterol 2.5 mg and greatest for levalbuterol 1.25 mg. Racemic albuterol 1.25 mg demonstrated the weakest bronchodilator effect, particularly after chronic dosing. The greatest increase in FEV₁ was seen after levalbuterol 1.25 mg, especially in subjects with severe asthma. All active treatments were well tolerated, and β-adrenergic side effects after administration of levalbuterol 0.63 mg were reduced relative to levalbuterol 1.25 mg or racemic albuterol 2.5 mg. At week 4, the predose FEV₁ value was greatest in patients who received levalbuterol or placebo when compared with those who received racemic albuterol. The difference was more evident and was statistically significant in patients who were not receiving inhaled corticosteroids. Conclusion: Levalbuterol appears to provide a better therapeutic index than the standard dose of racemic albuterol. These results support the concept that (S)-albuterol may have detrimental effects on pulmonary function. (J Allergy Clin Immunol 1998;102:943-52.)     

Infectious diseases and immunological markers associated with patients with non-Hodgkin lymphoma treated with rituximab

Background: The use of rituximab (RTX) is increasing, even in developing countries. It has become the first-line therapy or adjuvant to chemotherapy (CHOP; cyclophosphamide, hydroxydaunorubicin, oncovin and prednisone) for various diseases, including B cell lymphoma and autoimmune diseases.

Aim: We describe the infectious diseases and immunological markers associated with RTX treatment of patients with non-Hodgkin lymphoma (NHL).

Methods: Serum immunoglobulins were determined before and after intravenous immunoglobulin (IVIg) administration. Pneumo-23IgG-specific anti-pneumococcal antibodies were evaluated before and after vaccination. Immunophenotyping and lymphocyte proliferation were determined in the course of the treatment.

Results: Seven patients were followed and median age was 56.0?±?5.0?years (range, 41.9–71.6?years). At baseline, the mean level of IgG was 333.7?±?40.8?and IgM 40.9?±?11.3?mg/dL, respectively; immunoglobulin A and E (IgA and IgE) were under the limit of detection. Two patients had reduced or absent B cells and T cell subsets were at normal levels in five patients. All patients failed to mount an efficient post-vaccination immune response against hepatitis B virus, tetanus, diphtheria and against the 23-valent pneumococcal polysaccharide vaccine. During RTX/CHOP treatment, human-IgG-immunoglobulin (IVIg) therapy was introduced in six patients after recurrent infections, including community-acquired pneumonia (85.7%), chronic sinusitis (85.7%) and gastroenteritis (42.9%).

Conclusion: Poor response against pneumococcal vaccines increases the susceptibility of respiratory diseases in these patients. In patients with NHL treated with RTX, the benefits achieved with IVIg replacement for the control of recurrent infectious diseases is of paramount importance. Clinicians dealing with monoclonal antibodies against cancer therapy, especially RTX, should be aware of the increasing risks for symptomatic induced hypogammaglobulinemia and respiratory infections.     

Establishing Safety with Patients with Dissociative Identity Disorder

Abstract

The incidence of self-mutilation and suicidality among patients with dissociative disorders is quite high. It is necessary for clinicians working with this population to be adept at dealing with safety problems. This article presents a sequence of basic steps that can be used when helping dissociative patients establish safety, a discussion of the functions of self-destructiveness, and an overview of specific experiences and thinking patterns that contribute to self-destructiveness among dissociative patients.     

Gynecomastia with marked cellular atypia associated with chemotherapy

Gynecomastia is a common benign male breast disease, which may exhibit mild cellular atypia in cytology specimens. However, marked cytologic atypia can be seen in gynecomastia superimposed by chemotherapy. The case described in this report demonstrated severe cytologic atypia of gynecomastia mimicking carcinoma in a patient treated with chemotherapy for acute leukemia. A distinct cytologic feature helpful in avoiding the diagnostic error is described, namely, atypical cells admixed with bland ductal cells and appearing at a different plane. The importance of applying strict diagnostic criteria in breast cytology and clinical correlation is also emphasized.     

Intervention with epinephrine in hypotension associated with mastocytosis

The occurrence of the episodes of vasodilatory hypotension can be a life-threatening manifestation of systemic mastocytosis. This article describes the reversal by epinephrine of episodes of severe hypotension in two hospitalized patients with mastocytosis. Recognition of the efficacy of epinephrine in hypotension associated with mastocytosis can be important when other methods fail to restore hemodynamic stability.