凑型准分子激光器的发展及其在医学中的应用

由于在绝缘材料和气体放电技术方面的进展,处于紫外波段的准分子激光器已经在工业、科学研究,特别是医学等领域成为主要应用工具.在本文中,我们将介绍新颖紧凑型准分子激光器在医学中的应用.此外,在文章中对紧凑型准分子激光器所采用的关键技术,诸如固态开关、电晕预电离和金属/陶瓷腔等技术进行了详细的讨论.     

准分子激光眼科治疗机中激光器控制实现

准分子激光眼科治疗机可以用来进行近视、远视、散光等屈光不正的矫正手术。其中激光器的控制为手术提供能量稳定的激光脉冲,是对手术安全性、可靠性的重要保证。本文简述了一准分子激光眼科治疗机的整体组成部分,并详细描述了激光器的控制部分:计算机与激光器的通信控制、激光发射停止控制、充换气流程控制。目前,这种准分子激光治疗机已经应用于临床,并取得了良好的效果。     

准分子激光的医学应用

由于准分子激光对生物组织作用的独特机理─光化学分解作用,解决了许多临床治疗难题。近年来,难分子激光在激光医学中得到较广泛的应用。医用准分子激光种类主要有XeCl,308nm;ArF,193nm;KrF,248nm。本文介绍了准分子激光在医学中的几种典型应用。     

XeCl准分子激光对少根根霉的生物学效应和脂肪酶活性的相关性

利用XeCl准分子紫外激光照射少根根霉孢囊孢子,研究其生物学效应。在照射功率为2.0 kV,2.5kV和2.7 kV,脉冲次数为35-135的范围内,其致死曲线在85脉冲次数处形成高峰,在110脉冲次数处形成低谷,构成一个“峰形”曲线;与紫外灯UV致死曲线有较大的差别。通过琼脂平板分离、固态发酵,从中筛选到8株脂肪酶活力提高幅度10%以上的菌株,其中以突变株LB-5的酶活力最高,达66.4 IU/g干基,较出发菌株酶活提高了55.1%。讨论了激光照射功率、脉冲次数和致死率与根霉脂肪酶活力之间的关系。     

XeCl 准分子激光辐照生物大分子对其结构影响初步研究-Ⅰ308 nm紫外激光辐照小牛胸腺DNA的电镜观察与分析

XeCl 308 nm紫外激光(单脉冲输出能量33.4 mJ,脉冲频率 2次/秒,辐照时间45秒,光斑6×3 mm,透镜焦距300 mm)辐照330 mm处小牛胸腺DNA(固体).用扫描电子显微镜和透射电子显微镜可以观察到DNA受照射后有断裂、分叉、扭曲、聚集和交联等现象,影响生物大分子的初级结构和高级结构的变化.在我们的实验条件下是以影响DNA构象变化为主.     

角黄素及其在医学中的应用

角黄素是一种非维生素A源的酮式类胡萝卜素,具有抗氧化,免疫促进及增强细胞间隙连接通讯等多种生物学活性.大量的流行病学调查,组织培养,动物试验及人体干预试验表明,角黄素对多种癌症具有预防和治疗的功效.此外,角黄素还能够提高免疫力,保护皮肤和骨骼健康.目前市场上供应的角黄素产品主要通过有机化学合成制得.然而,天然角黄素容易吸收并且不涉及化学工艺而更受消费者欢迎.近年来,越来越多的产角黄素微生物菌株被分离和纯化,使得天然角黄素有进一步扩大应用的潜力和发展前景.从发酵培养的细菌中提取角黄素具有菌体繁殖速度快,生产周期短,发酵工艺较为成熟等优势,进行高细胞密度生产比较容易.因此,国外各国均把利用微生物发酵技术合成天然角黄素作为主攻方向,进行天然角黄素的研究与开发.在此,就角黄素的理化性质、医学应用、天然角黄素研究与开发的最新研究进展进行阐述和讨论,为我国角黄素的开发研究提供参考.     

系统生物学研究及其在医学中的应用

目前,系统生物学研究已初显端倪。生物学正从分子生物学走向系统生物学,由精细的分解研究转向系统的整体研究,由还原论的研究方法过渡到系统论的研究方法。简要论述了系统生物学的产生背景、结构和内容、研究思路和方法、与医学的关系等,重点介绍系统生物学的内容和研究方法,以及在疾病治疗和药物开发中的研究进展。     

转基因动物及其在医学中的应用

转基因动物是通过将外源目的基因导入受精卵或早期胚胎细胞中,使其稳定地整合到受体的基因组中,并得到表达的动物。这一技术已用来在哺乳动物的乳汁中生产贵重的治疗用蛋白,生产供人类移植用的器官,制造人类跗疾病的动物模型。其前景十分广阔。     

小波理论及其在医学信号处理中的应用

小波理论在最近几年发展极其迅速,它在不同领域中已取得了成功的应用．本文讨论小波和小波变换的性质,并借以小波理论是局部分析的有力工具,对一小段上医学信号的异常信息,可以很灵敏地通过小波系数反映出来．在医学信号处理中小波理论还能够被用作多功能滤波器．     

元基因组学及其在转化医学中的应用

微生物群落遍布于人体的每个角落,与人共生并对人体健康产生重要和深刻的影响。与人类共生的全部微生物的基因组总和称为“元基因组”或“人类第二基因组”。研究人体微生物群落及相关元基因组数据,对转化医学领域的基础研究和临床应用具有重要的价值。通过对生物医学相关的高通量元基因组数据进行分析,不仅能为基础医学研究向医学临床应用转化提供新思路和新方法,而且具有广阔的应用前景。基于新一代测序技术产生的数据,元基因组分析技术和方法能够弥补以往人体微生物先培养后鉴定方法的缺陷,同时能有效鉴定和分析微生物群落的组成及功能,从而进一步探究和揭示微生物群落与机体生理状态之间的关系,为解决许多医学领域的难题提供了全新的切入角度和思维方法。文章系统介绍了元基因组研究的现状,包括元基因组的方法概念和研究进展,并以元基因组在医学研究中的应用为着眼点,综述了元基因组在转化医学方面的研究进展,进一步阐述了元基因组研究在转化医学应用领域中具有的重要地位。     

Compact Cell Settlers for Perfusion Cultures of Microbial (and Mammalian) Cells

As microbial secretory expression systems have become well developed for microbial yeast cells, such as Saccharomyces cerevisiae and Pichia pastoris, it is advantageous to develop high cell density continuous perfusion cultures of microbial yeast cells to retain the live and productive yeast cells inside the perfusion bioreactor while removing the dead cells and cell debris along with the secreted product protein in the harvest stream. While the previously demonstrated inclined or lamellar settlers can be used for such perfusion bioreactors for microbial cells, the size and footprint requirements of such inefficiently scaled up devices can be quite large in comparison to the bioreactor size. Faced with this constraint, we have now developed novel, patent‐pending compact cell settlers that can be used more efficiently with microbial perfusion bioreactors to achieve high cell densities and bioreactor productivities. Reproducible results from numerous month‐long perfusion culture experiments using these devices attached to the 5 L perfusion bioreactor demonstrate very high cell densities due to substantial sedimentation of the larger live yeast cells which are returned to the bioreactor, while the harvest stream from the top of these cell settlers is a significantly clarified liquid, containing less than 30% and more typically less than 10% of the bioreactor cell concentration. Size of cells in the harvest is smaller than that of the cells in the bioreactor. Accumulated protein collected from the harvest and rate of protein accumulation is significantly (> 6x) higher than the protein produced in repeated fed‐batch cultures over the same culture duration. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:913–922, 2017     

Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs^1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling^1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman³, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.     

Triple-FRET Technique for Energy Transfer Between Conjugated Polymer and TAMRA Dye with Possible Applications in Medical Diagnostics

Three-component Förster resonance energy transfer (FRET) has been used to obtain efficient FRET between the cationic conjugated polymer (CCP) as donor and 5-carboxy tetramethylrhodamine (TAMRA) dye as acceptor, by using an intermediate donor, fluorescein. In spite of the fact that there is enough overlap between the emission spectra of CCP and absorption spectra of TAMRA, the efficiency of FRET between CCP and TAMRA is poor. The reason for this is that while the Förster critical distance is not very sensitive to the overlap, the FRET efficiency is extremely sensitive to it. However, it is observed that the FRET efficiency between CCP and TAMRA improves considerably when fluorescein is introduced in the solution. The triple FRET so obtained can be used for deoxyribonucleic acid sequence detection in medical diagnostics because the fluorescence emission from TAMRA is pH-insensitive.     

Metabolite induction via microorganism co-culture: A potential way to enhance chemical diversity for drug discovery

Microorganisms have a long track record as important sources of novel bioactive natural products, particularly in the field of drug discovery. While microbes have been shown to biosynthesize a wide array of molecules, recent advances in genome sequencing have revealed that such organisms have the potential to yield even more structurally diverse secondary metabolites. Thus, many microbial gene clusters may be silent under standard laboratory growth conditions. In the last ten years, several methods have been developed to aid in the activation of these cryptic biosynthetic pathways. In addition to the techniques that demand prior knowledge of the genome sequences of the studied microorganisms, several genome sequence-independent tools have been developed. One of these approaches is microorganism co-culture, involving the cultivation of two or more microorganisms in the same confined environment. Microorganism co-culture is inspired by the natural microbe communities that are omnipresent in nature. Within these communities, microbes interact through signaling or defense molecules. Such compounds, produced dynamically, are of potential interest as new leads for drug discovery. Microorganism co-culture can be achieved in either solid or liquid media and has recently been used increasingly extensively to study natural interactions and discover new bioactive metabolites. Because of the complexity of microbial extracts, advanced analytical methods (e.g., mass spectrometry methods and metabolomics) are key for the successful detection and identification of co-culture-induced metabolites.     

Lipidomics of human Meibomian gland secretions: Chemistry, biophysics, and physiological role of Meibomian lipids

Human Meibomian gland secretions (MGS) are a complex mixture of diverse lipids that are produced by Meibomian glands that are located in the upper and the lower eyelids. During blinking, MGS are excreted onto the ocular surface, spread and mix with aqueous tears that are produced by lachrymal glands, and form an outermost part of an ocular structure called “the tear film” (TF). The main physiological role of TF is to protect delicate ocular structures (such as cornea and conjunctiva) from desiccating. Lipids that are produced by Meibomian glands are believed to “seal” the aqueous portion of TF by creating a hydrophobic barrier and, thus, retard evaporation of water from the ocular surface, which enhances the protective properties of TF. As lipids of MGS are interacting with underlying aqueous sublayer of TF, the chemical composition of MGS is critical for maintaining the overall stability of TF. There is a consensus that a small, but important part of Meibomian lipids, namely polar, or amphiphilic lipids, is of especial importance as it forms an intermediate layer between the aqueous layer of TF and its upper (and much thicker) lipid layer formed mostly of very nonpolar lipids, such as wax esters and cholesteryl esters. The purpose of this review is to summarize the current knowledge on the lipidomics of human MGS, including the discussions of the most effective modern analytical techniques, chemical composition of MGS, biophysical properties of Meibomian lipid films, and their relevance for the physiology of TF. Previously published results obtained in numerous laboratories, as well as novel data generated in the author’s laboratory, are discussed. It is concluded that despite a substantial progress in the area of Meibomian glands lipidomics, there are large areas of uncertainty that need to be addressed in future experiments.