Directed Positioning of Micronuclei in Paramecium tetraurelia with Laser Tweezers: Absence of Detectible Damage After Manipulation

Possible covert damage from the use of the laser optical force trap (laser tweezers) to reposition micronuclei in Paramecium tetraurelia was assessed by measuring proliferation rates and postautogamous survival and mutation rates of cells after laser manipulations. No differences in subsequent daily proliferation rates among laser manipulated and various control classes of cells were seen. Similarly, the rates of postautogamous lethality and of “slow growth mutations” after repositioning of both micronuclei were not different from such rates in unmanipulated controls. In spite of extensive manipulations of micronuclei by the laser tweezers, there is no evidence of any damage induced by these manipulations. The laser tweezers therefore appears to be a tool of benign effect upon living cells, with tremendous potential use in many cell and developmental biological investigations.     

Nd^＋3：YAG激光对黑曲霉的诱变效应

本文采用Ｎｄ＾＋３：ＹＡＧ激光辐照柠檬酸生产菌黑曲霉孢子,辐照后进行培养和发酵试验,分析测定不同辐照时间黑曲霉孢子的存活率、黑曲霉菌丝体生长繁殖及颓丧 酸的速度、主要代谢产物柠酸的产量及淀粉糖化酶活力等变化。     

Nd：YAG1064nm激光、伊曲康唑治疗轻中度甲真菌病近期疗效分析

目的 观察Nd：YAG1064nm激光治疗机、伊曲康唑治疗甲真菌病的有效性及安全性.方法 选取符合入组条件的患者60例,病甲共125个.将60例患者随机分为A、B两组,A组予以Nd：YAG1064nm激光治疗;B组予以伊曲康唑口服治疗.每组均于第8周、第16周、第24周时随访,随访时予以真菌学评价及临床疗效评价.结果 A组第8周、16周、24周有效率分别为78.9％、52.6％、52.6％,B组第8周、16周、24周有效率分别为80.9％、66.2％、67.6％.A、B两组临床疗效差异无统计学意义（P＞0.05）.结论 激光治疗甲真菌病疗效肯定,且元不良反应.在轻中度甲真菌病患者中,激光治疗和药物治疗有效率差异不大.     

Ca2+ fluorescence imaging with pico- and femtosecond two-photon excitation: signal and photodamage.

The signal and limitations of calcium florescence imaging using nonresonant multiphoton absorption of near-infrared femto- and picosecond laser pulses were examined. The fluorescence changes of various Ca(2+)-indicators induced by transient increases of the intradendritic calcium concentration were evaluated by evoking physiological activity in neocortical neurons in rat brain slices. Photodamage was noticeable as irreversible changes in the parameters describing the calcium fluorescence transients. At higher two-photon excitation rates, a great variety of irregular functional and structural alterations occurred. Thus, signal and observation time were limited by phototoxic effects. At lower excitation rates, photodamage accumulated linearly with exposure time. Femtosecond and picosecond laser pulses were directly compared with respect to this cumulative photodamage. The variation of the pulse length at a constant two-photon excitation rate indicated that a two-photon excitation mechanism is mainly responsible for the cumulative photodamage within the investigated window of 75 fs to 3.2 ps. As a direct consequence, at low excitation rates, the same image quality is achieved irrespective of whether two-photon Ca(2+)-imaging is carried out with femto- or picosecond laser pulses.     

Retinoic acid and CO2 laser resurfacing

The purpose of this study was to analyze the effect of retinoic acid on wound healing and depth of injury in an animal skin model resurfaced with a CO2 laser. The dorsal skin of 21 Hartley guinea pigs was divided into halves. One-half received a daily application of 0.05% retinoic acid for 28 days, whereas the other half served as the control. The animals were divided into three treatment groups of seven animals. Group A was laser resurfaced with one pass of the Coherent UltraPulse CO2 laser (300 mJ, 60 W, density 40 percent). Group B received two passes, and group C received three passes. Histologic studies were obtained before laser resurfacing and days 1, 4, and 7 after resurfacing. Depth of injury, thickness, number of squamous cell and granular cell layers, and epithelialization rates were measured. We found that the depth of injury was statistically less in animals pretreated with retinoic acid. Granular cells were thicker and more numerous at day 4 in pretreated animals but similar to controls by day 7. Animals pre-treated with retinoic acid overall seemed to heal wounds earlier. In conclusion, pretreatment with retinoic acid may reduce the depth of injury in laser resurfacing and speed healing rates.     

激光辐照鱼类胚胎导致畸变

红激光(He—Ne,632.8nm)辐照金鱼(Carassius aurafus)受精卵和怀胎孔雀鱼(Poecilia reticulata),导致两种鱼胚胎畸变。金鱼胚胎在某一发自阶段的畸变率随辐照剂量的增加而提高;在同一剂量辐照下,不同发育期的胚胎畸变率各异,胚胎发育初期畸变率最高,此后随胚胎发育过程畸变率下降。经He—Ne激光辐照的孔雀亲鱼也能生产畸形仔鱼。在实验中还比较了红激光(632.8nm)和紫激光(N_2337.1nm)辐照金龟卵致变效果。     

He—Ne激光辐照天使鱼胚胎导致畸变

采用He—Ne激光(632.8nm辐照了天使鱼(Pterophyllum eimeki)的发育阶段的胚胎,观察和分析激光辐照对胚胎发育的致变影响和各发育阶段胚胎对激光的受激反应。对受精卵、囊胚期、原肠期和神经胚期的胚胎进行照射,均引起各期胚胎的畸变,这些畸变大多数是初孵仔鱼的头部、尾部、胸腔和背脊的变形。实验结果表明,天使鱼各个发育阶段的胚胎畸变率随着激光辐照剂量的改变而发生变化。     

Influence of laser light on mycelial growth of Hebeloma mesophaeum and ectomycorrhizal development on Scots pine

 The effects of exposure to helium-neon (He-Ne) or Argon (Ar) laser light (λ=632.8 nm and 514 nm, respectively) on the growth of Hebeloma mesophaeum mycelium in pure culture were studied. Growth rates were highest after exposure to the He-Ne laser (1×60 s)+Ar laser (2×60 s) and to the He-Ne laser for 3×30. Container-grown Pinus sylvestris (pine) seedlings were inoculated with a water suspension of H. mesophaeum mycelium previously exposed to different kinds of laser light. After 3 months, the percentage of mycorrhizal associations on pine roots was 34.3% higher after He-Ne laser treatment and 47.1% higher after Ar laser treatment than in the controls with untreated fungus. However, seedlings infected with treated fungus were smaller than the control. Overall, laser light stimulated growth of H. mesophaeum mycelia in pure culture and enhanced mycorrhizal development on Scots pine seedlings.     

翠绿宝石激光脱毛350例疗效分析

目的:评价翠绿宝石激光脱毛治疗的疗效。方法:使用波长为755 nm的GentleLASE Plus激光对350例门诊患者的不同部位的体毛进行多次治疗,并按不同部位和治疗次数进行分组,分析其疗效。结果:经过多次治疗后,总体治愈率为83.71%,疗效与不同的部位有关,且与治疗次数呈正相关。其中5例出现暂时性色素沉着。结论:使用GentleLASE Plus激光进行脱毛治疗效果良好,并发症少,是目前较为理想的脱毛治疗方法。     

A continuous wave laser T-jump apparatus and its application to chemical reactions in hemoglobin single crystals

A laser temperature jump apparatus is constructed where the T-jump is achieved by means of the direct absorption of continuous laser radiation of low intensity by a solid sample. The final temperature in the irradiated volume element is reached when the absorbed radiation power equals the dissipation of heat by heat conduction. The time range from the beginning of irradiation to the stationary state depends on the geometry of the irradiated volume element and is less than 10 ms. The heating laser beam is simultaneously used to detect the relaxation to the new chemical equilibrium in the sample. Relaxation processes with relaxation rates between 10(2) s-1 and less than 10(-3) s-1 on samples with volumes less than 10(-3) mm3 may be investigated using this T-jump method. One application of this method is the determination of reaction rates of ligand reactions in hemoglobin single crystals. Rate constants obtained for the reaction of thiocyanate with crystallized horse methemoglobin are presented.     

The efficiency of two-photon photolysis of a "caged" fluorophore, o-1-(2-nitrophenyl)ethylpyranine, in relation to photodamage of synaptic terminals

Localized photolysis of caged neurotransmitters with the two-photon effect for investigations at synaptic preparations was evaluated by determining the toxicity to synaptic transmission of pulsed near-IR laser light focused into the terminals of the snake neuromuscular junction, and measuring the extent of photolysis of a conventional caging group with similar irradiation in microcuvette experiments. Photodamage was seen in synaptic terminals as a large, irreversible increase of spontaneous synaptic activity with laser flashes of 5 ms at 1 Hz at average powers > 5 mW and was due to multiphoton absorption. Localized photolysis due to two-photon absorption was investigated for a representative caged fluorophore, the 1-(2-nitrophenyl)ethyl ether of pyranine (NPE-HPTS). Irradiation of NPE-HPTS at 5 mW with the same optical arrangement produced very low rates of photolysis. NPE-HPTS photolysis mechanisms were investigated at high laser powers by measuring (1) the kinetics of two-photon fluorescence generated by two-photon photolysis in the focal volume and (2) the rates of HPTS accumulation inside closed 2-10 microm radius vesicles, measured with one-photon excitation during two-photon photolysis by repetitive 10 micros laser exposures. The two-photon crosssection of NPE-HPTS photolysis calculated from the rates is 0.02-0.04 GM (10(-50) cm4 x s/photon) and limits the efficiency of photolysis at 5 mW. With free diffusional exchange, 50% steady-state cage depletion in the focal volume was estimated to occur only at high laser powers of ca. 72 mW, masked in experiments by multiphoton bleaching. Based on these results, the two-photon photolysis cross-section needed for 50% steady-state photolysis of a caged neurotransmitter at 5 mW is calculated as 31 GM, much higher than in existing caged compounds.     

两种藻胆蛋白对人肝癌SMMC-7721细胞的光动力体外杀伤效应

用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)法测定提取自条斑紫菜的R-藻红蛋白(R-PE)和C-藻蓝蛋白(C-PC)经激光介导对人肝癌SMMC-7721细胞的杀伤率,并检测细胞凋亡率。结果显示在120mg/L浓度下,R-PE在氩离子激光器100J/cm2辐照下对应的细胞存活率为27%,C-PC在He-Ne激光器35J/cm2辐照下对应的细胞存活率为47%;单用2种激光器辐照对应的细胞存活率分别为65%和70%;单用2种蛋白处理细胞在72h后出现对细胞生长的显著抑制,最大抑制率分别为31%(R-PE,120mg/L)和27%(C-PC,250mg/L)。120mg/L的2种藻胆蛋白在对应激光辐照下,于照后8h达到细胞凋亡率最大值,分别为31.54%(R-PE)和32.54%(C-PC)。本实验证明条斑紫菜R-PE和C-PC具有可开发成为光敏剂的应用前景。     

Quantification of erosion rates for undisturbed contaminated cohesive sediment cores by image analysis

In order to model the transport of cohesive sediments and associated contaminants accurately, knowledge of erosion rates is indispensable; at present, these are mostly obtained from the literature and usually extended by field data. In contrast to these theoretical approaches we have developed a method to determine erosion rates directly from experiments conducted with undisturbed sediment cores in a laboratory flume. Regularly spaced laser lines are projected onto the sediment surface during the erosion process. To compute the volume loss over a certain period of time, snapshots of the projected lines are taken and the relation between the deformed projected lines and the sediment surface is derived. With this relation and bilinear interpolation, the sediment surface is reconstructed. The volume difference between the reconstructed sediment surfaces corresponding to the snapshots is then calculated. Consequently, volume loss can be determined in mm³ per time with a maximum error of 7.2%. The average error is less than 1%. Combination with the bulk density results in erosion rates in kg m^–1 s^–1. The high sensitivity of the laser lines to sediment surface changes allows the determination of even small erosion rates. Thus, it is possible to determine erosion rates directly as a function of shear stress. Since it is possible to vary the area of calculated sediment-volume loss, scaling effects can be investigated as well.     

Study of bacteriophage T4-encoded Dam DNA (adenine-N6)-methyltransferase binding with substrates by rapid laser UV cross-linking

DNA methyltransferases of the Dam family (including bacteriophage T4-encoded Dam DNA (adenine-N(6))-methyltransferase (T4Dam)) catalyze methyl group transfer from S-adenosyl-L-methionine (AdoMet), producing S-adenosyl-L-homocysteine (AdoHcy) and methylated adenine residues in palindromic GATC sequences. In this study, we describe the application of direct (i.e. no exogenous cross-linking reagents) laser UV cross-linking as a universal non-perturbing approach for studying the characteristics of T4Dam binding with substrates in the equilibrium and transient modes of interaction. UV irradiation of the enzyme.substrate complexes using an Nd(3+):yttrium aluminum garnet laser at 266 nm resulted in up to 3 and >15% yields of direct T4Dam cross-linking to DNA and AdoMet, respectively. Consequently, we were able to measure equilibrium constants and dissociation rates for enzyme.substrate complexes. In particular, we demonstrate that both reaction substrates, specific DNA and AdoMet (or product AdoHcy), stabilized the ternary complex. The improved substrate affinity for the enzyme in the ternary complex significantly reduced dissociation rates (up to 2 orders of magnitude). Several of the parameters obtained (such as dissociation rate constants for the binary T4Dam.AdoMet complex and for enzyme complexes with a nonfluorescent hemimethylated DNA duplex) were previously inaccessible by other means. However, where possible, the results of laser UV cross-linking were compared with those of fluorescence analysis. Our study suggests that rapid laser UV cross-linking efficiently complements standard DNA methyltransferase-related tools and is a method of choice to probe enzyme-substrate interactions in cases in which data cannot be acquired by other means.     

1064nm Nd：YAG激光对5种甲真菌病重要致病菌的作用

目的观察1064nmNd：YAG激光对5种甲真菌病重要致病菌（红色毛癣菌、须癣毛癣菌、白念珠菌、近平滑念珠菌、烟曲霉）生长的影响。方法将各菌的菌悬液均匀点种于培养基上,生长至形成一定大小的菌落,给予不同能量1064nmNd：YAG激光照射,皮肤癣菌类观察激光照射后第1、3、6天菌落生长受抑制的直径变化情况;念珠菌类观察其次代培养存活率的差异;烟曲霉菌悬液铺满整个平皿,观察经不同能量激光照射受抑制的菌落空白处直径大小差异。结果在体外,当激光能量累计达到3200J／cm^2时,可对培养基上生长的以上各菌产生生长抑制作用,且随着能量增大,抑制作用增强,甚至可发生杀灭作用。结论1064nmNd：YAG激光当能量累计达到一定量时可对甲真菌病致病菌产生明显的生长抑制或杀灭作用。     

Ion recombination and energy balance in lead and gallium laser erosion plasmas

The ion recombination times, the energy balance characteristics, and the time behavior of the radiation intensity of lead and gallium laser plasmas are determined by analyzing the trailing edges of the waveforms of various spectral lines. Reasons for different decay rates of the spectral lines are analyzed. Experiments on laser erosion of lead and gallium targets under the action of repetitive neodymium laser radiation with a pulse duration of 20 ns, wavelength of 1.06 μm, repetition rate of 12 Hz, and peak intensity on the target surface of 10⁸–10⁹ W/cm² were carried out at a residual air pressure of 3–12 Pa.     

Biochemical applications of a synchronously pumped krypton ion dye laser fluorescence system.

A synchronously pumped krypton ion dye laser fluorescence system is shown to provide tunable, polarized, subnanosecond pulses at high repetition rates, modest peak powers, and low energy. Such a source is uniquely suited to fluorescence investigations of biochemical mechanisms. Applications of this fluorescence excitation source to analysis, life-time determination, and depolarization effects are discussed.     

High rates of conjugation in bacterial biofilms as determined by quantitative in situ analysis.

Quantitative in situ determination of conjugative gene transfer in defined bacterial biofilms using automated confocal laser scanning microscopy followed by three-dimensional analysis of cellular biovolumes revealed conjugation rates 1,000-fold higher than those determined by classical plating techniques. Conjugation events were not affected by nutrient concentration alone but were influenced by time and biofilm structure.     

The effect of compliance on wall shear in casts of a human aortic bifurcation

Rigid and compliant casts of a human aortic bifurcation were subjected to physiologically realistic pulsatile fluid flows. At a number of sites near the wall in the approximate median plane of the bifurcation of these models, fluid velocity was measured with a laser Doppler velocimeter, and wall motion (in the case of the compliant cast) was determined with a Reticon linescan camera. The velocity and wall motion data were combined to estimate the instantaneous shear rates at the cast wall. Analysis showed that at the outer walls the cast compliance reduced shear rates, while at the walls of the flow divider the shear rate was increased.     

Laser angioplasty of peripheral arteries after unsuccessful recanalization of the superficial femoral artery

AIM: To demonstrate the range of applying laser angioplasty after unsuccessful recanalization of the superficial femoral artery (SFA) with conventional interventional techniques. MATERIALS AND METHODS: In a prospective trial in 94 cases with occlusion of the SFA and formerly unsuccessful conventional percutaneous transluminal angioplasty, laser angioplasty for recanalization was applied. The average occlusion length of the SFA was 17.5 cm (range 4-36 cm). The recanalization attempt was made using the crossover technique in 78 patients, in eight patients with the antegrade technique and in another eight patients using the transpopliteal technique. The primary recanalization attempt was performed with Terumo wires (curved and straight) as well as different catheters (Multipurpose/Vertebralis/Cobra). After the unsuccessful recanalization attempt the laser catheter was applied. RESULTS: The application of laser angioplasty demonstrated a successful recanalization of the SFA in 76/94 patients (80.9%). In 18 patients (19.1%) the recanalization was not possible even with percutaneous transluminal laser angioplasty (PTLA). The reason for the unsuccessful PTLA was in 10 cases due to obstructing calcified material, which was resistant to PTLA application. In four cases obstructing calcifications caused the laser catheter to be positioned in subintimal tissue, resulting in perforation of the SFA. In another four patients there was an aberrant anatomy of the SFA which resulted in a direct vessel injury after advancing the laser catheter. After a follow-up period of 12 months primary, primary-assisted and secondary patency rates were 50.0%, 65.8% and 73.7%, respectively. DISCUSSION: In primarily unsuccessful recanalization of the SFA, PTLA allows in 80% of cases a successful recanalization of the SFA. The technical success rate and the patency rate support the application of PTLA.