Transport processes of fluid exchange in the crystalline lens of the rabbit eye

Processes of fluid exchange in the crystalline lens of the rabbit eye were investigated. The direction of movement of fluid in the crystalline lens was investigated from the movement of fluorescein by the method of "stopped diffusion". It has been found that the mechanism of fluid transport in the crystalline lens is active and is carried out by means of the Na-kappa-ATPase transport system. The energy necessary for the active transport of fluid inside the crystalline lens is in the range (1.5-6) x 10(-2) J. Owing to the active fluid transport, the pressure inside the crystalline lens constantly increases by 6 mm Hg. In rabbit's life-time, the movement of fluid in the crystalline lens occurs in the direction from the anterior to the posterior surface followed by the exit to vitreous humor.     

北京萤火虫复眼的模型小眼设计与光线追迹

以实际的北京萤火虫复眼结构与生理参数与依据,基于已知的ＧＲＩＮ透镜特征,把小眼的整个光学系统分成几个部分被模型化。模型中,在晶体柱部分使用了一个径向梯度折射率透镜柱具有的抛物线轮廓折射率公式;在晶锥末端所接的半椭球ＧＲＩＮ透镜部分,使用了一个径向梯度和纵向梯度分布都存在的折射率公式．模型的尺寸与折射率的大小根据实际晶锥的测量值．通过对模型小眼的光线追迹,证明模型小眼基本上是一个平行光入射,年行光出射的望远镜系统．小眼光学系统的前半部分把入射的平行光束聚焦到中间焦点,而这个点的位置恰好位于实际晶锥的腰的部位,而光线再次经过晶锥近端以后又以大致平行光束从晶锥末端出射。此模型小眼的最大入射角为３０度,在这个入射角内其角放大率基本上是相同的。随着对平行入射光束与小眼光轴的角度的增加,所产生的中间像越来越远离晶锥光轴。     

The Energetics of Acoustic Signaling in Anurans and Insects

SYNOPSIS. This review focuses on the energetics of advertisementcalls in frogs and insects (mostly ensiferans). I also reviewa number of methodological questions relating to the most appropriateways to normalize metabolic rates for calling animals and tocalculate efficiency of sound production Although the mechanism of sound production is very differentin these groups (vocalization vs. stridulation), net metaboliccosts normalized to mass are similar among species producingthe most conspicuous calls. Features of the call that interactto determine energetic cost include repetition rate, call duration,and intensity (sound pressure level). Anurans tend to producelouder (more intense) calls while ensiferans tend to producesound during a greater proportion of the calling bout. All evidencesuggests that advertisement calls are produced aerobically andthe aerobic costs are similar or exceed the aerobic (but notnecessarily total costs) of terrestrial locomotion The pattern of radiated sound tends to be constant within aspecies and can be predicted to some degree from characteristicsof an animal's acoustic radiator. Efficiency of sound production(acoustic power/net metabolic power) is low (0.05 to 6%) andvariable when compared to locomotion ({small tilde} 10–20%).From the present sample it appears that frogs are more efficientthan ensiferans, but as more katydids are studied this trendmay not hold. Of the factors that have been identified as determiningefficiency the most important are the match between the sizeof the radiator and wavelength radiated, the absorption propertiesof the environment immediately around the animal, and the presenceor absence of structures such as baffles and acoustic burrows     

Ultrahigh frequency lensless ultrasonic transducers for acoustic tweezers application

Similar to optical tweezers, a tightly focused ultrasound microbeam is needed to manipulate microparticles in acoustic tweezers. The development of highly sensitive ultrahigh frequency ultrasonic transducers is crucial for trapping particles or cells with a size of a few microns. As an extra lens would cause excessive attenuation at ultrahigh frequencies, two types of 200‐MHz lensless transducer design were developed as an ultrasound microbeam device for acoustic tweezers application. Lithium niobate single crystal press‐focused (PF) transducer and zinc oxide self‐focused transducer were designed, fabricated and characterized. Tightly focused acoustic beams produced by these transducers were shown to be capable of manipulating single microspheres as small as 5 µm two‐dimensionally within a range of hundreds of micrometers in distilled water. The size of the trapped microspheres is the smallest ever reported in the literature of acoustic PF devices. These results suggest that these lensless ultrahigh frequency ultrasonic transducers are capable of manipulating particles at the cellular level and that acoustic tweezers may be a useful tool to manipulate a single cell or molecule for a wide range of biomedical applications. Biotechnol. Bioeng. 2013; 110: 881–886. © 2012 Wiley Periodicals, Inc.     

Methods for measuring acoustic power of an ultrasonic neurosurgical device

Measurement of the acoustic power in high-energy ultrasonic devices is complex due to occurrence of the strong cavitation in front of the sonotrode tip. In our research we used three methods for characterization of our new ultrasonic probe for neuroendoscopic procedures. The first method is based on the electromechanical characterization of the device measuring the displacement of the sonotrode tip and input electrical impedance around excitation frequency with different amounts of the applied electrical power The second method is based on measuring the spatial pressure magnitude distribution of an ultrasound surgical device produced in an anechoic tank. The acoustic reciprocity principle is used to determinate the derived acoustic power of equivalent ultrasound sources at frequency components present in the spectrum of radiated ultrasonic waves. The third method is based on measuring the total absorbed acoustic power in the restricted volume of water using the calorimetric method. In the electromechanical characterization, calculated electroacoustic efficiency factor from equivalent electrical circuits is between 40-60%, the same as one obtained measuring the derived acoustic power in an anechoic tank when there is no cavitation. When cavitation activity is present in the front of the sonotrode tip the bubble cloud has a significant influence on the derived acoustic power and decreases electroacoustic efficiency. The measured output acoustic power using calorimetric method is greater then derived acoustic power, due to a large amount of heat energy released in the cavitation process.     

Dopamine Induces Optical Changes in the Cichlid Fish Lens

The crystalline lens in the cichlid fish Aequidens pulcher undergoes a transformation of its optical properties every dawn and dusk as the eye adapts to changes in light conditions. During dusk the transformation result in an increase of the refractive power in the lens cortex, the outermost 40 percent. The change is thought to match the optical properties of the lens to the requirements of the retina. Using a short term in vitro lens culturing system together with optical measurements we here present data that confirm that the optical properties of the lens can change within hours and that dopamine influences the optical properties of the lens. Dopamine yields dose-dependent decrease of the refractive power in the lens cortex. The D1-agonist SKF-38393 induces a similar decrease of the refractive power in the cortex, while the D2-agonist quinpirole has no effect. The effect of dopamine can be blocked by using the D1-antagonist SCH 23390. Our results suggest that dopamine alone could be responsible for the light/dark adaptive optical changes in the lens, but the involvement of other signaling substances cannot be ruled out.     

Tumor cytotoxicity in vivo and radical formation in vitro depend on the shock wave-induced cavitation dose

Local tumor therapy using focused ultrasonic waves may become an important treatment option. This technique exploits the ability of mechanical waves to induce thermal and nonthermal effects noninvasively. The cytotoxicity to cultured cells and biological tissues in vivo that results from exposure to ultrasonic shock waves is considered to be a nonthermal effect that is partly a consequence of ultrasound-induced cavitation. Cavitation is defined as the formation of bubbles during the negative wave cycle; their subsequent oscillation and/or violent implosion can affect surrounding structures. To investigate cavitational effects in cells and tissues, defined cavitation doses must be applied while ideally holding all other potential ultrasound parameters constant. The application of independent cavitation doses has been difficult and has yielded little knowledge about quantitative cavitation-tissue interactions. By using a special shock-wave pulse regimen and laser optical calibration in this study, we were able to control the cavitation dose independently of other physical parameters such as the pressure amplitudes, and averaged acoustic intensity. We treated Dunning prostate tumors (subline R3327-AT1) transplanted into Copenhagen rats with shock waves at three cavitation dose levels and then determined the tumor growth delay and the histopathological changes. All of the treated animals exhibited a significant tumor growth delay compared to the controls. Higher cavitation doses were associated with a greater delay in the growth of the tumor and more severe effects on tumor histopathology, such as hemorrhaging, tissue disruption, and necrosis. In vitro, the cavitation dose level correlated with the amount of radical formation. We concluded that the process of acoustic cavitation was responsible; higher cavitation doses caused greater effects in tumors both in vivo and in vitro. These findings may prove important in local tumor therapy and other applications of ultrasound such as ultrasound-mediated drug delivery.     

江豚眼折光系统的初步研究

本文对江豚(Neomeris phocaenoides)眼折光系统的各个组成部分——角膜、前房水、晶状体和玻璃体进行了解剖学和光学参数的测量.对江豚简约眼的各项光学参数进行了计算.根据解剖学测量和简约眼的计算结果对江豚眼的折射状态作了估计.结果表明,江豚眼角膜的曲率较小其折光能力较弱,而其晶状体的折光能力却较强,在眼的折光系统中起着主要作用.江豚眼的折射误差(refractive error)为-25.1D,,说明江豚为高度近视眼,只有当物体靠得很近时,江豚的视觉才起作用.文章把江豚眼折光系统的实验结果与某些陆生哺乳动物的实验结果作了比较,讨论了水生哺乳动物与陆生哺乳动物眼折光系统的某些差别.     

体外冲击波碎石焦点附近声压分布的时域有限差分法数值解析

泌尿系统结石症是一种多发病。体外冲击波碎石(Extracorporealshockwavelithotropisy,ESWL)法是应用人体外发射的高强度脉冲超声波在人体内的焦点附近形成的冲击波破碎结石,被破碎的结石碎片随尿液排出体外的治疗泌尿系统结石症方法。由于这种治疗方法具有非创伤等优点而被广泛地应用于泌尿系统结石症的治疗。但是,ESWL治疗过程中有时会引发尿血、肾血肿等并发症,影响其治疗效果的主要因素之一为ESWL焦点附近形成的声压分布。在这里,利用作者等以前提出的时域有限差分(finitedifferencetimedomain,FDTD)超声波非线性传播的仿真方法,数值仿真ESWL超声波非线性传播过程,研究ESWL焦点附近声压的分布、焦点区域(焦区)的大小形状、高强度超声波形成的实际焦点位置。     

Spatial and acoustic pressure dependence of microbubble-mediated gene delivery targeted using focused ultrasound

BACKGROUND: Ultrasound/microbubble-mediated gene delivery has the potential to be targeted to tissue deep in the body by directing the ultrasound beam following vector administration. Application of this technology would be minimally invasive and benefit from the widespread clinical experience of using ultrasound and microbubble contrast agents. In this study we evaluate the targeting ability and spatial distribution of gene delivery using focused ultrasound. METHODS: Using a custom-built exposure tank, Chinese hamster ovary cells in the presence of SonoVue microbubbles and plasmid encoding beta-galactosidase were exposed to ultrasound in the focal plane of a 1 MHz transducer. Gene delivery and cell viability were subsequently assessed. Characterisation of the acoustic field and high-resolution spatial analysis of transfection were used to examine the relationship between gene delivery efficiency and acoustic pressure. RESULTS: In contrast to that seen in the homogeneous field close to the transducer face, gene delivery in the focal plane was concentrated on the ultrasound beam axis. Above a minimum peak-to-peak value of 0.1 MPa, transfection efficiency increased as acoustic pressure increased towards the focus, reaching a maximum above 1 MPa. Delivery was microbubble-dependent and cell viability was maintained. CONCLUSIONS: Gene delivery can be targeted using focused ultrasound and microbubbles. Since delivery is dependent on acoustic pressure, the degree of targeting can be determined by appropriate transducer design to modify the ultrasound field. In contrast to other physical gene delivery approaches, the non-invasive targeting ability of ultrasound makes this technology an attractive option for clinical gene therapy.     

Limits of the confocal laser-scanning technique in measurements of time-resolved autofluorescence of the ocular fundus]

GOAL: The 2-dimensional measurement of the time-dependent autofluorescence has in combination of confocal laser scanner technique and time correlated single photon counting the potential for the investigation of the metabolism state at the eye ground. It was to be examined, to what extent these measurements are influenced through the auto-fluorescence of the crystalline lens. MATERIAL AND METHOD: The time-dependent auto-fluorescence was measured on eyes of 21 patients with age-related macular degeneration (AMD) and of 26 healthy subjects in 40 degrees fundus images. The experimental set-up used, was developed at the eye clinic of the University of Jena. In this scanning laser ophthalmoscope, the fundus was excited at 446 nm by pulses of 100 ps full width at half maximum and 40 MHz repetition rate. The auto-fluorescence was detected with a time resolution of 25 ps for wavelengths > 500 nm. The dynamic auto-fluorescence of each pixel was approximated by a tri-exponential model function. In order to determine the influence of the fluorescence of the crystalline lens, healthy eyes and eyes were compared with implanted artificial intra-ocular lenses. For comparison the frequency distributions were used, which the decay times t1, t2 and t3 in the fundus images had been calculated with. RESULTS: Clear differences were shown in the frequency distributions of the fluorescence lifetimes between AMD-patients and healthy subjects, It resulted, however, from a crucial analysis that the fluorescence of the crystalline lens is not suppressed by the confocal laser scanning principle sufficiently. In particular the long lifetime t3 is overlapped by the fluorescence of the crystalline lens of about 4.6 ns. To the complete suppression of the influence of the lens fluorescence in measurements of the time-resolved fundus auto-fluorescence it is suggested to combine the confocal laser scanning technique with the principle of the aperture diaphragm division. CONCLUSION: In order to be able to determine the capability of measurements of the time-dependent fundus auto-fluorescence as diagnostic tool exactly, the influence of the crystalline lens is to reduce through the combination of confocal laser scanning ophthalmoscopy with the principle of the aperture diaphragm division diversely.     

Identification of the FTBL protein of Sumner and Dounce as a leucine aminopeptidase

The crystalline beef liver protein of Sumner and Dounce (A. L. Dounce, P. Z. Allen, and G. A. Mourtzikos (1978) Arch. Biochem. Biophys. 188, 251-265) termed FTBL (football) protein because of the shape of its crystals, has been identified as a crystalline leucine aminopeptidase (LAP), on the basis of its high specific LAP activity and coincidence of its N terminal amino acid sequence (30 amino acids) with that of beef eye lens LAP. Amino acid analyses of the two proteins are also in reasonable agreement when based on the exact monomer molecular weight of beef eye lens protein obtained by the van Loon group ((1982) J. Biol. Chem. 257, 7077-7081). Our previously published monomer molecular weight of the FTBL protein was 25% too high, leading to the erroneous conclusion that the beef liver FTBL-LAP protein was a tetramer rather than a hexamer, as found by the van Loon group for beef lens LAP. The present report, taken together with our first paper on the FTBL protein establishes that the FTBL-LAP protein has been isolated from beef kidney and beef spleen as well as from beef liver. We now find that the properties of FTBL-LAP protein indicate that it is the same protein as beef eye lens LAP. The cellular and intracellular distributions of the FTBL-LAP protein have been considered in our first publication on the FTBL protein.     

Experimental Investigation of Focusing of Gold Planar Plasmonic Lenses

To experimentally demonstrate the subwavelength focusing of depth-tuned or non-depth-tuned plasmonic lenses, we first designed this type of lens using diffraction-coupling-angle based method, then fabricated the structure in gold thin film with focused ion beam, and finally characterized its focusing behavior using near-field scanning optical microscope. It is found that this type of lens has a resolution limit on the focal plane due to the field represented by angular spectrum having a cut-off frequency, while at the near field the lens has sub-diffraction limit focusing capability due to the existence of high-angular-frequency components in the field.     

Twin-beam laser velocimeter for the investigation of spermatozoon motility

Previous laser light-scattering studies of spermatozoon motility have been hampered by the large, asymmetric shape of spermatozoa, which causes difficulties in the interpretation of intensity fluctuations in the light scattered from a single laser beam. This paper describes an experimental arrangement for measuring the distribution of transit times for swimming spermatozoa using two slightly separated, focused laser beams. The theory of operation of the instrument is developed to enable the analysis of the experimentally obtained cross-correlation functions. The effects of the pronounced spermatozoon asymmetry and associated intensity modulation in the scattered light are also investigated and shown to be negligible for the twin beam experimental arrangement, provided that the swimming speed distribution has a coefficient of variation (sigma/upsilon greater than 0.1. Results obtained using this apparatus are presented for the velocity distribution of spermatozoa from a variety of bulls.     

Immunology of Staphylococcal biofilm infections in the eye: new tools to study biofilm endophthalmitis

Endophthalmitis is an important disease of the eye that is most frequently caused by postoperative and post-traumatic introduction of bacteria into the posterior segment of the eye. In the case of severe infections, visual acuity is greatly damaged or completely lost. Much work has focused on the ability of planktonic bacteria to cause infection and ocular damage while little work has focused on chronic infections in endophthalmitis mediated by the formation of bacterial biofilms on the surface of the lens. This review focuses on the interaction of Staphylococcus aureus and Staphylococcus epidermidis lens-associated biofilms in endophthalmitis. Additionally, this review highlights some relevant biofilm-immune system interactions and outlines a new in vivo mouse model to explore biofilm-related infections in endophthalmitis.     

Eye fluke infection and lens size reduction in fish: a quantitative analysis

Parasites have a variety of harmful effects on their hosts, some of which may be overlapping or complementary and thus easily overlooked but which are still important for the overall severity of infection. We investigated the effect of Diplostomum sp. eye fluke infection on the size of the eye lens in a range of wild and farmed fish species and those exposed to controlled parasite infection. We found that asymmetry in intensity of infection between the right and left lens of an individual fish affected lens size such that the lens with the higher intensity of infection was smaller. Interestingly, however, this was observed only in 3 of the 10 species studied (whitefish, smelt and sea trout) although in these 3 species the effect had already became evident at low intensities of infection. Furthermore, the average lens size was significantly smaller in experimentally exposed whitefish Coregonus lavaretus with a higher intensity of infection than the controls, emphasising the sensitivity of this species to parasite-induced changes in lens size. Reduction in lens size may contribute to the deleterious effects of cataract formation by intensifying the effects of individual parasites in the lens. It may also directly affect the overall optical performance of the lens and already impair host vision at low intensities of infection.     

Three-Dimensional Mid-Air Acoustic Manipulation by Ultrasonic Phased Arrays

The essence of levitation technology is the countervailing of gravity. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes. The acoustic axis of the ultrasound beam in conventional studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally) by controlling the phases or frequencies of bolted Langevin-type transducers. In the present study, we considered extended acoustic manipulation whereby millimetre-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays. Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its centre is also utilised. The other is the manipulation principle by which a localised standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays. We experimentally confirmed that expanded-polystyrene particles of 0.6 mm, 1 mm, and 2 mm in diameter could be manipulated by our proposed method.     

Thermal acoustic radiation from multilamellar vesicles in lipid phase transition

A new acoustical method for the investigation of lipid phase transition is introduced based on the measurement of the thermal acoustic radiation (TAR) inherent in lipids. The TAR of multilamellar vesicles from dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) was measured in the megahertz range and the variations in the radiation intensity during the lipid phase transition were recorded. Two types of variations are possible: if the temperature of the vesicles decreases (in the process of transition from the liquid crystalline state to the gel state) then the TAR intensity increases, and if the temperature increases (in the reverse transition) then the TAR intensity decreases. These effects are connected with an increase in the ultrasonic absorption in the vesicles under lipid phase transition. Basing on the results of the TAR investigation, a new theoretical estimate has been developed of the variation in the absorption coefficient during the lipid phase transition. In this estimate, the variation is equated to the ratio of the phase transition entropy to the gas constant.     

用于全眼段成像和视轴参数测量的四焦点开关光学相干断层扫描

本文演示了四焦点开关傅里叶域光学相干断层扫描系统用于全眼段成像和体内视轴参数(VAP)测量的可行性.使用包括不同厚度平行玻璃板的两个同步转盘来将探测光束的焦点位置从角膜以及晶状体的前部和后部切换到视网膜.该过程同时增加了参考光束的深度范围.这种多级聚焦的方法可以使探测光束完全聚焦在人眼的每个部分.初步实验表明,该方法可...     

Polarization Effect on Superfocusing of a Plasmonic Lens Structured with Radialized and Chirped Elliptical Nanopinholes

Tuning effect of different polarization states was presented in this paper. It can be realized by a plasmonic lens constructed with elliptical pinholes ranging from submicron to nanoscales distributed in variant period along radial direction. Propagation properties of the lens illuminated under four different polarization states: linear, elliptical, radial, and cylindrical vector beam, were calculated and analyzed combining with finite-difference time-domain algorithm. Different focusing performances of the lens were illustrated while the polarized light passes through the pinholes. Our calculation results demonstrate that polarization effect of the elliptical pinholes-based plasmonic lens can generate high transmission intensity and sharp focusing for our proposed specific structures. Beam focal region, position, and transmission intensity distribution can be tailored by the four polarization states.