Bioengineering and subjective approaches to the clinical evaluation of dry skin

Dry skin (also known as xerosis) is a cutaneous reaction pattern indicative of abnormal desquamation, which has not only cosmetic considerations, but can also lead to the penetration of irritants and allergens through the stratum corneum (SC). Over the last few decades, our understanding of the structure, composition, formation and function of the SC has advanced tremendously; however, despite these advancements, the occurrence of dry skin remains prevalent in the adult population. The clinical evaluation of dry skin is therefore of significant importance to the cosmetic industry not only for understanding the condition but also for measuring the effects of treatment. Traditionally, dry skin has been evaluated by visual inspection, however, recently a variety of bioengineering techniques have emerged enabling the investigator to objectively assess the extent of xerotic conditions. The most frequently employed methods for the evaluation of dry skin are discussed in this review, including regression testing, squametry, measurement of transepidermal water loss, epidermal hydration, profilometry, confocal Raman spectroscopy, optical coherence tomography, in vivo confocal microscopy and magnetic resonance imaging.     

玉米皮中亚油酸超临界CO2萃取技术的研究

采用超临界CO2选择性萃取技术从玉米皮中提取亚油酸(LA)。对影响LA提取率的主要因素压力、温度、时间及CO2流量进行研究和分析,并利用气相色谱法(GC)对玉米皮亚油酸(CSLA)进行定性定量分析。通过正交试验优化萃取工艺条件,当萃取压力25MPa,萃取温度35℃,萃取时间90min,CO2流量25L/h时萃取效果最好,此时LA提取率为3.41g/100g玉米皮。     

微生物合成共轭亚油酸机理的研究进展

相比于共轭亚油酸（CLA）的化学合成,微生物合成CLA与化学法具有培养灵活、对设备要求低、产物分离简单等优势。主要讨论了微生物合成CLA的研究进展,亚油酸（LA）能被微生物转化的原因,以及微生物合成CLA的机理。CLA的合成机理从微生物在动物瘤胃内混合发酵代谢LA和单一微生物在体外合成CLA两方面进行阐述。     

Effectiveness of oils rich in linoleic and linolenic acids to enhance conjugated linoleic acid in milk from dairy cows

Forty Holstein dairy cows were used to determine the effectiveness of linoleic or linolenic-rich oils to enhance C_18:2cis-9, trans-11 conjugated linoleic acid (CLA) and C_18:1trans-11 (vaccenic acid; VA) in milk. The experimental design was a complete randomized design for 9 wk with measurements made during the last 6 wk. Cows were fed a basal diet containing 59% forage (control) or a basal diet supplemented with either 4% soybean oil (SO), 4% flaxseed oil (FO), or 2% soybean oil plus 2% flaxseed oil (SFO) on a dry matter basis. Total fatty acids in the diet were 3.27, 7.47, 7.61, and 7.50 g/100 g in control, SO, FO, and SFO diets, respectively. Feed intake, energy-corrected milk (ECM) yield, and ECM produced/kg of feed intake were similar among treatments. The proportions of VA were increased by 318, 105, and 206% in milk fat from cows in the SO, FO, and SFO groups compared with cows in the control group. Similar increases in C_18:2cis-9, trans-11 CLA were 273, 150, and 183% in SO, FO, and SFO treatments, respectively. Under similar feeding conditions, oils rich in linoleic acid (soybean oil) were more effective in enhancing VA and C_18:2cis-9, trans-11 CLA in milk fat than oils containing linolenic acid (flaxseed oil) in dairy cows fed high-forage diets (59% forage). The effects of mixing linoleic and linolenic acids (50:50) on enhancing VA and C_18:2cis-9, trans-11 CLA were additive, but not greater than when fed separately. Increasing the proportion of healthy fatty acids (VA and CLA) by feeding soybean or flaxseed oil would result in milk with higher nutritive and therapeutic value.     

产亚油酸异构酶的乳酸菌的筛选

对16株乳酸菌产亚油酸异构酶（linoleate isomerase）的能力进行分析,紫外分光光度法和气相色谱法分析发酵液中的共轭亚油酸（CLA）,筛选出产亚油酸异构酶的乳酸菌,PCR扩增筛选出菌株的亚油酸异构酶基因,并对其进行序列分析。结果显示,通过紫外分光光度法检测16株乳酸菌中有9株菌可将亚油酸（LA）转化为共轭亚油酸（CLA）;气相检测6株乳酸菌的发酵液中存在cis-9,trans-11CLA和trans-10,cis-12CLA两种同分异构体（各占CLA总产量的50%）;成功扩增出鼠李糖乳杆菌与亚油酸异构酶密切相关的肌球蛋白交叉反应抗原（MCRA）基因片段。      

一株植物乳杆菌转化生成共轭亚油酸的特性研究

报道了一株植物乳杆菌(L.plantarumLT2-6)发酵转化亚油酸(LA)生成共轭亚油酸(CLA)的特性研究。微氧环境有利于CLA的生成;温度为37℃、初始pH为7.0、底物LA浓度为0.075%时,菌体生长及CLA生成量较高。时间曲线结果表明,接种后8h,CLA开始生成;发酵24h时,CLA生成量达到最高(0.29g/L),LA转化率为387%。生成的CLA产物主要为cis9,trans11/trans9,cis11-CLA。     

精氨酸-共轭亚油酸抗氧化活性研究

测定了精氨酸-共轭亚油酸清除超氧阴离子自由基(O2-.)、羟自由基(.OH)和二苯代苦味肼基自由基(DPPH.)的能力,并与VC的抗氧化活性进行了比较。结果表明:精氨酸-共轭亚油酸对3种自由基的清除能力均与其浓度存在着量效关系;精氨酸-共轭亚油酸对O2-.有一定的清除作用,但清除能力低于VC;精氨酸-共轭亚油酸对.OH和DPPH.有较强的清除作用,且清除能力均高于VC。在精氨酸和共轭亚油酸的协同作用下,精氨酸-共轭亚油酸的抗氧化活性得到增强。因此,精氨酸-共轭亚油酸是一种有效的抗氧化剂。     

植物乳杆菌亚油酸异构酶的分离纯化及其性质研究

经硫酸铵分级沉淀、阴离子交换层析和凝胶过滤,由植物乳杆菌(LactobacillusplantarumL 2 9)分离纯化得到亚油酸异构酶,分子量为4 3ku。对其酶学性质进行研究,结果表明,温度37℃、pH 6 0时酶活性较高;Co2 + 、Fe2 + 可提高酶的活性,Cu2 + 、Zn2 + 则对酶活力有抑制作用;该酶作用于亚油酸的Km=2 5 3×10 -5mol/L ,Vmax=2 5 7×10 -8mol/ (min·mg)。     

植物乳杆菌ZS2058生物转化产物共轭亚油酸的分析方法的研究

研究了紫外分光光度法、GC、Ag~+-HPLC和GC-MS四种分析方法对植物乳杆菌ZS2058生物转化亚油酸(LA)产生的共轭亚油酸(CLA)检测时的异同点。结果表明,这4种分析方法在对CLA进行检测时各有特色,应用范围也有不同。紫外分光光度法检测成本最低,操作最快速,但检测结果为转化产物中各种CLA异构体的总和,而GC、Ag~+-HPLC和GC-MS能将产物中的各类CLA异构体分开,可对复杂的生物转化产物进行分析。其中,GC的最大优点在于可以检测到转化底物LA,Ag~+-HPLC可将转化产物中c9,t11-CLA和t8,c10- CLA很好的分离,而GC-MS可以将各种异构体与其它副产物明确区分开来。总之,在检测生物转化法产生的CLA时,根据不同的实验需求来选择不同的检测方法,并需将这几种方法灵活的结合起来应用。     

一株嗜酸乳杆菌合成共轭亚油酸的条件优化

以嗜酸乳杆菌(Lactobacillus acidophilus)1.1854为出发菌株,经紫外诱变和诱导处理,获得1株共轭亚油酸(CLA)高产菌株,通过五因素二次正交旋转组合设计对该菌株合成共轭亚油酸的条件进行了优化。其优化条件为:培养温度37℃、pH值4.5～5.5、LA浓度0.1%、接种量5%～7%、培养时间24h,此时CLA产率达31.2%。     

Oxidation and textural characteristics of butter and ice cream with modified fatty acid profiles

The primary objective of this study was to evaluate oxidation and firmness of butter and ice cream made with modified milkfat containing enhanced amounts of linoleic acid or oleic acid. The influence of the fatty acid profile of the HO milkfat relating to product properties as compared with the influence the fatty acid profile of the HL milkfat was the main focus of the research. Altering the degree of unsaturation in milkfat may affect melting characteristics and oxidation rates, leading to quality issues in dairy products. Three milkfat compositions (high-oleic, high-linoleic, and control) were obtained by modifying the diets of Holstein cows. Ice cream and butter were processed from milkfat obtained from cows in each dietary group. Butter and ice cream samples were analyzed to determine fatty acid profile and firmness. High-oleic milkfat resulted in a softer butter. Solid fat index of high-oleic and high-linoleic milkfat was lower than the control. Control ice cream mix had higher viscosity compared with high-oleic and high-linoleic, but firmness of all ice creams was similar when measured between -17 and -13 degrees C. Nutritional and textural properties of butter and ice cream can be improved by modifying the diets of cows.     

亚油酸异构酶研究进展

亚油酸异构酶可催化亚油酸异构化为共轭亚油酸.随着共轭亚油酸的应用日益广泛,人们对亚油酸异构酶的研究也日益深入.在查阅大量文献的基础上,对亚油酸异构酶国内外的研究情况进行了综述.     

植物乳杆菌ZS2058转化亚油酸为共轭亚油酸条件的初步研究

研究了植物乳杆菌ZS2058转化亚油酸为共轭亚油酸的条件,在培养基中添加10g/L吐温-80制成LA-吐温-80胶束溶液,可以提高CLA的转化率,最佳转化温度为35℃,添加1mg/mL的LA有较高的转化率和CLA产量。在MRS、SKM、KPB三种转化体系中SKM的转化率较高。在含LA的培养基中预培养12h,可以提高CLA的转化率。最佳转化接种量在1%～2%之间。      

植物乳杆菌转化合成共轭亚油酸的培养基条件优化

生物法转化合成共轭亚油酸,产物中异构体组成单一,具有很好的应用前景。通过一株植物乳杆菌(Lactobacillus plantarum)合成共轭亚油酸的培养基成分进行优化,确定最优的培养基组成:葡萄糖20g/L,酵母浸出物40g/L,硫酸镁0.5g/L,硫酸锰0.5g/L,乙酸钠2g/L,磷酸氢二钾1g/L。优化后,共轭亚油酸产量达到0.259g/L,相比优化前(0.0455g/L)有了较大的提升。      

酶法合成共轭亚油酸的研究进展

共轭亚油酸（conjugated linoleic acid,CLA）是一类具有抗癌、抗动脉粥样硬化和降脂等多种生理活性的功能性脂肪酸的统称,在食、药和畜牧业领域极具应用潜力。CLA的天然来源有限,主要依赖于化学法和生物法合成。利用生物法合成的CLA,异构体单一且食用安全,是合成CLA方式的最佳选择。其中,利用酶法合成CLA因具有产物高纯度和高含量、合成高效率等优势,成为当今研究热点。该文对酶法合成CLA途径以及合成途径中关键酶的研究现状进行综述,为提高生物合成CLA效率提供参考。     

共轭亚油酸合成相关基因在耶氏解脂酵母中异源表达及活性研究

为了探究植物乳杆菌(Lactobacillus plantarum)中与共轭亚油酸(CLA)生物合成相关的3个基因:(亚)油酸水合酶基因(mcra)、短链脱氢酶/氧化还原酶基因(dh)、乙酰乙酸脱羧酶基因(dc)在耶氏解脂酵母(Yarrowia lipolytica,Y.lipolytica)中异源表达后能否具有活性,利用两个耶氏解脂酵母整合表达质粒(p INA 1269和p INA 1312),将3个基因分别导入耶氏解脂酵母营养缺陷型宿主菌Polf(Ura~-,Leu~-)中,构建了重组菌株。在不同重组菌中添加相应的底物:亚油酸(LA)和10-羟基-顺12-十八碳烯酸(10-HOE),然后对反应体系进行脂肪酸检测,得到基因对应的不同产物:10-HOE和10-氧代-反11-十八碳烯酸(10-oxo-trans 11-octadecenoic acid),证明mcra、dh、dc在耶氏解脂酵母中进行了异源表达并且具有活性。     

嗜酸乳杆菌发酵法制备亚油酸异构酶的研究

以正交试验确定了嗜酸乳杆菌的最佳发酵条件，对其产生的亚油酸异构酶以硫酸铵分级沉淀和Sephadex G100层析进行了分离，并测定了酶活力。结果表明，嗜酸乳杆菌适宜发酵条件为：温度40℃，初始pH6．5，接种量1％，发酵时间24h；以上条件下产生的亚油酸异构酶经纯化后测得酶活为4358．6U。     

共轭亚油酸合成原料的研究进展

共轭亚油酸(Conjugated Linoleic Acid,CLA)具有抗肿瘤、减少脂肪蓄积、调节机体免疫力、抗动脉粥样硬化、调节血糖血压、预防骨质疏松等多种生理活性,已经被广泛应用于医药、食品、保健品、化妆品等领域。由于CLA天然来源较少,以亚油酸为底物人工合成制备CLA成为了人们获取CLA的主要途径。本文系统介绍了游离脂肪酸、烷烃酯、甘油酯等不同形式的亚油酸及来源广泛、价格低廉的天然油脂在CLA生产中的运用,并综述了食品发酵中CLA的合成,为优化CLA原料利用、经济高效地获取CLA提供了参考。     

碱异构化花生油制备共轭亚油酸工艺优化

目的:为了获得具有工业化前景的共轭亚油酸(Conjugated linoleic acid, CLA)制备工艺。方法:以花生油为原料,采用碱异构化法制备CLA。测定了花生油中的亚油酸相对含量,考察了反应时间、反应温度、醇油比、催化剂KOH用量等因素对CLA转化率的影响,并通过Box-Behnken试验优化制备条件。结果:花生油富含亚油酸(相对含量达27.85%),是制备CLA的良好原料;碱异构化花生油制备CLA的最优条件为：反应温度200℃,反应时间2.6 h,醇油比(m_{1,2-丙二醇}∶m_亚油酸)22∶1,KOH用量(质量分数)7%。在该条件下,CLA转化率为89.81%。结论:采用碱异构化花生油制备CLA的工艺可行,在最优工艺条件下,CLA转化率高。