激光生物作用及其影响因子

本文对影响激光生物作用的因子进行了讨论。组织的吸收和散射、入射激光束的直径以及含色素组织的尺寸等因子决定了激光作用下组织中光能的沉积区域，短激光脉冲能在光能沉积区内产生最强的光热和光机械作用。在高强度激光的辐照下，组织焦斑的形成会改变光能沉积区，并改变激光生物作用效果。     

激光生物作用及其影响因子

本文对影响激光生物作用的因子进行了讨论，组织的吸收和散射，入射激光束的直径以及含色素组织的尺寸等因子决策了激光作用下组织中光能的沉积区域，短激光脉冲能在光能沉积区内产生最强的光热和光机械作用，在高强度激光的辐照下，组织焦斑的形成会改变光能沉积区，并改变激光生物作用效果。     

氦氖激光对小鼠软脑膜微循环及血脑屏障的影响

本文研究了低功率氦氖激光对小鼠软脑膜微循环及血脑屏障的影响,观察到小鼠软脑毛细血管血流速度明显加快,管径扩张,开放数增加,而毛细血管通透性无改变。氦氖激光对小鼠软脑膜微循环的影响器材:JG-Ⅰ型氦氖激光综合治疗机,输出功率4.5MW,聚焦照射光斑直径4mm。WX-753B 型微环显微镜配摄像机及监视器。WXS—Ⅱ型数字血流测速仪。半导体点温计。方法:1.实验采用昆明种小白鼠90只,体重25-30克。随机均分为甲乙2组,甲组为激光照射组,用1%戊巴比妥钠(0.05 ml/     

激光的生物学效应与育种

一、激光的生物学效应:He-Ne和CO_2激光可使大豆和棉花苗叶面发皱、叶形变形、颜色发绿、棉苗叶柄加长、叶柄-茎间夹角变小、真叶高于茎尖、红茎率变大。后期子棉、皮棉、衣分增加,而绿豆则花序增多。He-Ne激光抑制小麦乳期苗的生长,Ar~+激光的这种作用则不明显。经He-Ne处理的小麦愈伤组织花药出愈率比CO_2和Ar~+的高三倍。He-Ne,CO_2和Ar~+激光均有改变小麦口松的作用,其效果和材料及激光种类有关。口松特性的改变在L_2代中有遗传。激光处理可改变籽粒的品质。CO_2     

不同激光脉冲作用下ZnS晶体非线性光学特性

用Z-scan技术在532 nm的皮秒激光脉冲和800 nm飞秒激光脉冲作用下分别研究了ZnS晶体的非线性吸收及非线性折射特性。实验结果表明,ZnS晶体在532 nm的皮秒激光脉冲作用下非线性吸收为双光子吸收,其非线性吸收系数为5.310-11 m/W,在800 nm的飞秒激光脉冲作用下非线性吸收为三光子吸收,非线性吸收系数为0.5910-21 m2/W2;在532 nm皮秒激光脉冲作用下,ZnS晶体的非线性折射率符号为负,自由载流子产生的非线性折射率的改变占主导,而800 nm飞秒激光脉冲作用下,ZnS晶体的非线性折射率符号为正,束缚电子产生的非线性折射率的改变为主要因素。     

氟化氩激光器适于作辐射状角膜切除术

各种准分子激光对眼作用的研究表明193 nm ArF激光最适于作辐射状角膜切除术的切口。在角膜上作这些切口，目的是改变眼的曲率半径而减轻近视程度。伊里诺斯大学医学院的Gholam Peyman及其同事比较了XeCl、KrF和ArF准分子激光对动物眼组织的作用。三者之中ArF准分子激光输出波长最短，作的切口最精细，而光凝固作用最轻。     

激光瞬间作用后金属表层特性及机理研究

本文讨论了强激光瞬间作用金属表面后金属表层特性的改变。分析和实验得出，通过控制入射激光功率密度和作用时间可以实现相交硬化及快速熔化——凝固处理。指出利用脉冲激光并选择适当的工艺参数可以有效地对金属工件进行表面处理以改进其硬度、耐磨及耐腐蚀等性能。     

微波对中枢神经系统的作用

中枢神经系统是机体对微波作用甚为敏感的部位 ,许多研究人员已运用生理、生化和分子生物学手段从形态、功能、代谢等方面对微波的中枢神经系统效应进行了系统研究 ,取得有价值的成果。1　微波对脑组织形态的影响病理学研究发现 ,功率密度 2 5ｍＷ /ｃｍ2 以上的微波辐射可导致 1中枢神经内组织充血、出血等典型热性损害以及神经元尼氏体溶解、胞浆空泡化、线粒体变形肿胀、融合断裂等。微波对血脑屏障的影响也很受重视。多数学者认为低功率微波辐射不能改变血脑屏障的通透性 ,只有当热效应导致脑组织温度达 40～ 45℃以上 ,才能使ＨＥＰ透…     

用超快激光飞秒脉冲在细胞内进行外科手术

恰像超快激光的聚焦光束能改变透明无机材料(如玻璃)微观特性那样，超快激光飞秒脉冲也能改变透明有机材料的微观结构，在上述两种情况中，超快激光脉冲使材料烧蚀或解离．其作用时间很短，因而使其在周围材料中所产生的热量最小。     

激光对体外培养肝癌细胞影响的组织化学观察

在用激光治疗肿瘤的研究中,由于观察到激光处理时的有害反应(例如激光直接作用于暴露的肿瘤时,会向四周溅起大量有再生能力的肿瘤碎屑)而限制了它在临床的应用。因此,改进激光的治疗效应,了解激光对细胞杀伤作用的性质及其机理,便成为值得注意的问题。本实验以体外培养的肝癌细胞株为材料。用不同强度的激光辐照后,观察其组织化学反应的改变,为分析激光对肝癌细胞的作用提供参考依据。     

Camouflaging Nanoparticles with Brain Metastatic Tumor Cell Membranes: A New Strategy to Traverse Blood–Brain Barrier for Imaging and Therapy of Brain Tumors

Glioblastoma multiforme is one of the most fatal intracranial tumors with no effective treatment. The drug concentration in tumor sites is usually insufficient to reach therapeutic levels, due to poor blood–brain‐barrier (BBB) permeability and short biological half‐life. Inspired by the proneness of those malignant tumors to brain metastasis, a brain metastatic tumor cell membrane‐coated nanocarrier with core–shell structure is constructed to cross BBB for imaging and photothermal therapy of early brain tumors. The cell membranes as the shell are extracted from different metastatic tumor cells, which endow the nanoparticles with BBB‐crossing ability and long circulation. Indocyanine green (ICG)‐loaded polymeric nanoparticle as the core allows fluorescence imaging and phototherapy of brain tumors. The as‐prepared biomimetic nanoparticles display superb BBB penetration and effective suppression of tumor growth. These findings suggest the biomimetic nanotechnology provides a new insight for the design of BBB‐crossing nanomaterials and is promising to treat brain diseases.     

Autocatalytic Delivery of Brain Tumor–Targeting,Size‐Shrinkable Nanoparticles for Treatment of Breast Cancer Brain Metastases

Breast cancer brain metastases (BCBMs) represent a major cause of morbidity and mortality among patients with breast cancer. Chemotherapy, which is widely used to treat tumors outside of the brain, is often ineffective on BCBMs due to its inability to efficiently cross the blood‐brain barrier (BBB). Although the BBB is partially disrupted in tumor lesions, it remains intact enough to prevent most therapeutics from entering the brain. Here, a nanotechnology approach is reported that can overcome the BBB through synthesis of lexiscan‐loaded, AMD3100‐conjugated, shrinkable nanoparticles (NPs), or LANPs. LANPs respond to neutrophil elastase–enriched tumor microenvironment by shrinking in size and disrupt the BBB in tumors through lexiscan‐mediated modulation. LANPs recognize tumor cells through the interaction between AMD3100 and CXCR4, which are expressed in metastatic tumor cells. The integration of tumor responsiveness, tumor targeting, and BBB penetration that enables LANPs to penetrate metastatic lesions in the brain with high efficiency is demonstrated and, when doxorubicin is encapsulated, LANPs effectively inhibit tumor growth and prolong the survival of tumor‐bearing mice. Due to their high efficiency in penetrating the BBB for BCBMs treatment, LANPs have the potential to be translated into clinical applications for improved treatment of patients with BCBMs.     

Theranostic USPIO‐Loaded Microbubbles for Mediating and Monitoring Blood‐Brain Barrier Permeation

Efficient and safe drug delivery across the blood‐brain barrier (BBB) remains one of the major challenges of biomedical and (nano‐) pharmaceutical research. Here, it is demonstrated that poly(butyl cyanoacrylate)‐based microbubbles (MB), carrying ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles within their shell, can be used to mediate and monitor BBB permeation. Upon exposure to transcranial ultrasound pulses, USPIO‐MB are destroyed, resulting in acoustic forces inducing vessel permeability. At the same time, USPIO are released from the MB shell, they extravasate across the permeabilized BBB and they accumulate in extravascular brain tissue, thereby providing non‐invasive R ₂*‐based magnetic resonance imaging information on the extent of BBB opening. Quantitative changes in R ₂* relaxometry are in good agreement with 2D and 3D microscopy results on the extravascular deposition of the macromolecular model drug fluorescein isothiocyanate (FITC)‐dextran into the brain. Such theranostic materials and methods are considered to be useful for mediating and monitoring drug delivery across the BBB and for enabling safe and efficient treatment of CNS disorders.     

Brain-Targeted Exosomes-Based Drug Delivery System to Overcome the Treatment Bottleneck of Brainstem Glioma

Brain health is the humans’ primary goal in achieving health and longevity. Brainstem glioma (BSG) has a high disability and mortality rate, posing a serious threat to children's brain health. Delivery of drugs to the brainstem is limited by poor tumor targeting and low blood-brain barrier (BBB) permeability. Thus, it is a great challenge to construct intracranial drug delivery systems with strong biocompatibility, low immunogenicity, and high BBB permeability for the delivery of drugs targeting BSG. Exosomes, as the next generation of novel delivery systems, have been widely used to across the BBB due to their advantages of good biocompatibility, stability, and permeability of the BBB and have made corresponding breakthroughs in targeted drug delivery for CNS diseases. This review summarizes natural, polypeptide functionalized, and physical methods-assisted brain-targeted exosomes-based drug delivery systems, the drug treatment bottleneck of BSG, and highlights the potential of using a brain-targeted exosomes-based drug delivery system to overcome the drug treatment bottleneck of BSG. It provides new insights into using exosomes-based drug delivery for BSG treatment.     

Design and experimental evaluations of a low-frequency hemispherical ultrasound phased-array system for transcranial blood-brain barrier disruption

The purpose of this paper is to demonstrate a prototype design of a low-frequency multiple-channel hemispherical focused-ultrasound phased-array system for transcranial disruption of the blood–brain barrier (BBB). A 32-channel ultrasound driving system tunable in the frequency range from 200 to 400 kHz was designed for producing a suitable ultrasound output for BBB disruption. The driving system includes a microcontroller/field-programmable gate-array-based control kernel with multiple-channel driving circuits implemented by a high-voltage switching/LC-resonance/impedance-matching circuit module. Three hemispherical phased arrays comprising 22, 31, and 80 elements were fabricated and tested. The pressure distributions at the geometric center and at off-center positions were tested experimentally. The focal performance of the different hemispherical arrays was also evaluated theoretically. The results showed that the developed phased-array system can successfully drive the hemispherical array with multiple-channel ultrasound signals with independent phase control at 8-bit resolution. Good focusing abilities were evident both at the geometric center and at specific off-center target positions. Preliminary animal experiments show that the BBB in rat can be locally disrupted successfully. The system will serve as a reference platform for developing a focused-ultrasound system for clinical use in brain drug delivery applications.      

Endo/Lysosome‐Escapable Delivery Depot for Improving BBB Transcytosis and Neuron Targeted Therapy of Alzheimer's Disease

The effective treatment of Alzheimer's disease (AD) is hindered due to the hard blood–brain barrier (BBB) penetration and non‐selective distribution of drugs in the brain. Moreover, the complicated pathological mechanism of AD involves various pathway dysfunctions that limit the effectiveness of a single therapeutic drug. Herein, a dendrigraft poly‐l ‐lysines (DGL)‐based siRNA and D peptide (Dp) loaded nanoparticle is designed that could target and penetrate through the BBB, enter the brain parenchyma, and further accumulate at the AD lesion. In this system, T7 peptide, which specifically targets transferrin receptors on the BBB, is linked to DGL via acid‐cleavable long polyethylene glycol (PEG) to achieve high internalization, quick escape from endo/lysosome, and effective transcytosis. Then, the Tet1, which specifically targets diseased neurons, is modified onto DGL by short PEG. After being exposed, Tet1 could drive the nanoparticles to the AD lesion and release the drugs. As a result, the production of β amyloid plaques (Aβ) is inhibited. Neurotoxicity induced by Aβ plaques and tau proten phosphorylation (p‐tau) tangle is also alleviated, and the cognition of AD mice is significantly improved. Overall, this system programmatically targets BBB and neurons, thus, significantly enhances the intracephalic drug accumulation and AD treatment efficacy.     

Acid‐Responsive Transferrin Dissociation and GLUT Mediated Exocytosis for Increased Blood–Brain Barrier Transcytosis and Programmed Glioma Targeting Delivery

Receptor mediated transcytosis (RMT) is a common mechanism used for nanotherapeutics to traverse the blood–brain barrier (BBB). However, the transcytosis of ligand modified nanoparticles via RMT is likely to be trapped within brain capillary endothelial cells due to the high binding affinity of ligand with receptors, which greatly reduces the amount of nanoparticles across BBB. Here, P‐aminophenyl‐α‐D‐mannopyranoside (MAN) decorated doxorubicin‐loaded dendrigraft poly‐l‐lysine with acid‐cleavable transferrin (Tf) coating outside (DD‐MCT) is proposed. The DD‐MCT is engineered to specifically recognize the Tf receptor (TfR) on the luminal side of BBB endothelium. Then the DD‐MCT undergoes an acid‐responsive cleavage of Tf, leading to the separation of MAN‐decorated DGL‐DOX (DD‐M) from the Tf–TfR complex in endo/lysosomes. The detached DD‐M is more prone to escape from endo/lysosomes and can further be exocytosed into brain parenchyma via the mediation of glucose transporter located on the abluminal endothelial membrane. Moreover, the DD‐M in brain parenchyma can target glioma cells. Significantly, the DD‐MCT enters into brain parenchyma in greater amounts, resulting in enhanced accumulation at glioma site and thus improved antiglioma therapeutic outcome. This strategy pioneers a new path for reducing the trapping of nanotherapeutics within BBB endothelium but increasing their transcytosis into brain parenchyma.     

三芯片集成高显色指数白光LED的研究

运用基于蒙特卡罗的光线追迹方法,对采用"光转换"兼"多色混合"技术的白光LED的显色指数、相关色温、光通量、光辐射功率、荧光粉颗粒密度和色坐标进行了仿真计算和优化选择。通过改变红、绿、蓝三种LED芯片的组合方式和红、绿、黄三种荧光粉的混合方式及各色荧光粉的密度,在保证有合理的光通量输出的条件下,得到了不同色温区的高显色指数白光LED。从显色指数角度看,冷白、正白和暖白光应分别选择BBB芯片+绿、红色荧光粉、BBB芯片+黄、红色荧光粉和RBB芯片+黄色荧光粉组合。实验上测试了采用这几种组合方式的白光LED光谱、显色指数、色温、光通量和色坐标,实验数据与仿真结果基本吻合。     

Cascade-Amplifying Synergistic Therapy for Intracranial Glioma via Endogenous Reactive Oxygen Species-Triggered “All-in-One” Nanoplatform

Targeted delivery of drug-loaded nanoparticles to brain tumors is exceptionally difficult due to the blood-brain barrier (BBB). In addition, several chemotherapeutic drugs induce autophagy, which protects the cells from apoptosis and mitigates the therapeutic effect. A novel “all-in-one” nanoparticles (AMPTL) consisting of endogenous reactive oxygen species-cleavable thioketal linkers conjugated to paclitaxel (PTX) and autophagy inhibitor 3-methyladenine, and angiopep-2 peptide-modified DSPE-PEG_2K is developed. AMPTL inhibits autophagy in the C6 glioma cells, as indicated by fewer autophagic vesicles, lower LC3-II expression and accumulation of SQSTM1/P62, and significantly upregulates p53 and the pro-apoptotic Bax and cleaved caspase-3 proteins. In addition, AMPTL treatment induces cell cycle arrest at the G2/M phase. Thus, inhibition of autophagy in the AMPTL-treated glioma cells sensitizes them to PTX-induced cell cycle arrest and apoptosis. Furthermore, focused pulse ultrasound and microbubbles enhances the delivery of AMPTL to intracranial glioma tissues by reversibly opening the BBB, which significantly inhibits xenograft growth and markedly improves survival rates of the tumor-bearing mice. Taken together, combining non-invasive BBB opening with autophagy inhibitors and chemotherapeutic drugs can achieve cascade-amplifying synergistic therapeutic effects against glioma.     

Multifunctional Photonics Nanoparticles for Crossing the Blood–Brain Barrier and Effecting Optically Trackable Brain Theranostics

Theranostic photonic nanoparticles (TPNs) that cross the blood–brain barrier (BBB) and efficiently deliver a therapeutic agent to treat brain diseases, simultaneously providing optical tracking of drug delivery and release, are introduced. These TPNs are constructed by physical encapsulation of visible and/or near‐infrared photonic molecules, in an ultrasmall micellar structure (<15 nm). Phytochemical curcumin is employed as a therapeutic as well as visible‐emitting photonic component. In vitro BBB model studies and animal imaging, as well as ex vivo examination, reveal that these TPNs are capable of transmigration across the BBB and subsequent accumulation near the orthotopic xenograft of glioblastoma multiforme (GBM) that is the most common and aggressive brain tumor whose vasculature retains permeability‐resistant properties. The intracranial delivery and release of curcumin can be visualized by imaging fluorescence produced by energy transfer from curcumin as the donor to the near‐infrared emitting dye, coloaded in TPN, where curcumin induced apoptosis of glioma cells. At an extremely low dose of TPN, a significant therapeutic outcome against GBM is demonstrated noninvasively by bioluminescence monitoring of time‐lapse proliferation of luciferase‐expressing U‐87 MG human GBM in the brain. This approach of TPN can be generally applied to a broad range of brain diseases.