Laser division of the aryepiglottic folds for severe laryngomalacia

Laryngomalacia is an entity of ill-defined etiology. The clinical situation is one of inspiratory stridor present at birth, or within the newborn period. The stridor may increase in severity for the first several months of life and thereafter spontaneously begins to resolve. In the majority of cases the condition resolves spontaneously by approximately two years of age. This report will present the surgical management of severe laryngomalacia in infants using the carbon dioxide laser to surgically divide the aryepiglottic fold with resolution of the laryngomalacia.     

激光扫描共聚焦显微镜的原理与生物学应用

激光扫描共聚焦显微镜在光学显微镜基础上结合了激光和计算机图象处理技术，把光学显微镜的分辨率提高了３０－４０％，其光学切片性能使观察组织、细胞的三维结构成为可能。本文简要介绍了共聚焦显微镜的历史和成象原理，着重介绍了其在生物学领域的应用，如样品的三维定量测量及活细胞的动态信号监测，并结合新兴的光生物学技术，如光镊、笼锁化合物的解笼锁、细胞分选、光漂白后的荧光恢复，探讨了激光共聚焦显微镜在激光细胞生物学的应用前景     

Laser Doppler measurements of cochlear blood flow

Blood flow to the inner ear was studied with a laser Doppler system in the acute guinea pig. Flow was measured through the lateral wall of the basal turn. Changes in simultaneous measures of cochlear and skin flow with rebreathing, epinephrine, phentolamine and terminal bleeding were studied. Cochlear blood flow followed skin blood flow in most cases; where it did not, the change was in an expected direction. The laser Doppler flowmeter appears to provide a direct, dynamic and linear measure of inner ear blood flow.     

Selective photothermal interaction using an 805-nm diode laser and indocyanine green in gel phantom and chicken breast tissue

. Laser immunotherapy, a novel therapy for breast cancer, utilises selective photothermal interaction to raise the temperature of tumour tissue above the cell damage threshold. Photothermal interaction is achieved with intratumoral injection of a laser-absorbing dye followed by non-invasive laser irradiation. When tumour heating is used in combination with immunoadjuvant to stimulate an immune response, antitumour immunity can be achieved. In this study, the selective photothermal effect was investigated using gel phantom and chicken breast tissue. An 805-nm diode laser and indocyanine green (ICG) were used. An ICG-containing gelatin phantom was constructed to simulate targeted tumour tissue. The target gel was buried inside chicken breast tissue and the tissue–gel construct was irradiated by the laser. Temperatures at different locations in the construct were measured during the laser irradiation. For comparison, the thermal effect of an Nd:YAG laser on the tissue–gel construct was also investigated. Selective heating of target gel containing 0.27% ICG and buried 1 cm below the chicken tissue surface was achieved with the 805-nm diode laser using a power of 0.85 W and beam radius of 1 cm. The target gel experienced a temperature increase of more then 6°C whereas the surrounding chicken breast tissue experienced only a minor temperature increase. The feasibility of this experimental set-up has been shown. It will be used in the future to optimise treatment parameters such as laser power, laser beam radius, and dye concentration. Paper received 17 April 2002; accepted 3 May 2002. Correspondence to: W.R. Chen, Biomedical Engineering Program, Department of Physics and Engineering, University of Central Oklahoma, Edmond, OK 73034, USA. Tel.: (405) 974-5198; Fax: (405) 974-3812; e-mail: wchen@ucok.edu     

The corneal thickness and intraocular pressure story: where are we now?

A review of the current literature was conducted regarding the effect of corneal thickness on the diagnosis of glaucoma, and the influence of excimer laser refractive surgery on intraocular pressure (IOP) measurement with Goldmann applanation tonometry. In general, normals and primary open angle glaucoma patients have a similar distribution of corneal thickness; however, there is a wide variation, ranging from 427 to 716 micro m. Normal tension glaucoma patients have a tendency towards thinner corneas than normals; however, there is an overlap of thickness measurements of more than two-thirds in 95% of patients. There is a trend for ocular hypertensives to have thicker corneas than normals, but again there is an overlap of about one-third in 95% of patients. The general trend after excimer laser refractive surgery is for a decrease in IOP, with a mean fall in IOP measured of 0.63 mmHg per dioptre correction. There is, however, a large scatter of values with some patients having the same or lower IOP post-laser, but with other patients measuring higher pressures. Corneal thickness can influence IOP measurement by Goldmann applanation tonometry; however, the magnitude of the effect is subject to much individual variation.     

Improved leukocyte tracking in mouse retinal and choroidal circulation

The purpose of this study is to develop a new method with which to visualize leukocyte dynamics in murine choroidal and retinal circulation. Both pigmented (B10.RIII) and non-pigmented (BALB/c) mice were used in this study. One hundred microl of 0.05% sodium fluorescein was injected via the mice tail vein to outline the vessel, followed by 150 microl (10(7) cells) C-AM labelled leukocytes. Fundus images were obtained with a confocal scanning laser ophthalmoscope. The dynamic image sequences were recorded simultaneously on videotape (S-VHS) and digitally at 25 frames per sec. The digital images were later analysed with a custom-made personal computer-based image analysis system. Both the choroidal and retinal circulation can be visualized in non-pigmented mice in the first few seconds of fluorescein angiography. However, the view of the choroidal and the retinal capillary circulation is soon blurred due to the rapid fluorescein leakage in the choroid. In contrast, in pigmented mice, retinal circulation is clear against the dark background of the choroid, while choroidal circulation is masked behind the pigment epithelial layer and cannot be seen at all. C-AM labelled leukocytes were clearly seen in the retinal circulation of all experimental mice and in the choroidal circulation of non-pigmented mice for as long as 30 min. The number of labelled circulating cells decreased as time clasped. Cells moved rapidly in the retinal arteries, slowing down or even stopping for a few seconds in the capillary system, and then moved slightly faster again through the postcapillary venules and veins. In non-pigmented mice, significant number of cells were seen to have arrested in the choroidal circulation. There was no difference between B10.RIII mice and BALB/c mice in vessel diameters, leukocyte velocities and shear stresses. This method allows the visualization of leukocytes and provides data on their behavior as they move through the choroidal and retinal circulation of non-pigmented mice, and in the retinal circulation of pigmented mice. It provides a valuable new tool for the investigation of real time leukocyte dynamics in murine retinal and choroidal microcirculations both under physiological conditions and during the development of ocular disease.     

Cerebral thrombosis and microcirculation of the rat during the oestrous cycle and after ovariectomy

1. The effects of oestrogen on thrombogenesis and the cerebral microcirculation of the female rat were studied during the oestrous cycle and after ovariectomy. 2. Serum levels of oestradiol (E2) and plasma concentrations of nitric oxide (NO) metabolites were significantly greater at pro-oestrus than at dioestrus. Blood vessel diameter, mean red cell velocity, wall shear rate and blood flow at pro-oestrus were significantly higher than at dioestrus. Thrombotic tendency, assessed using a He-Ne laser-induced thrombosis model, was significantly decreased at pro-oestrus compared with dioestrus. 3. The long-term deprivation of oestrogen by ovariectomy significantly depressed serum levels of E2 and plasma concentrations of NO metabolites. Thrombotic tendency was significantly increased 4 weeks after ovariectomy. Vessel diameter, mean red cell velocity, wall shear rate and blood flow in pial arterioles were significantly reduced after ovariectomy. 4. Exogenous administration of oestrogen (17 beta-oestradiol) after surgery reversed the increased thrombotic tendency mediated by ovariectomy. 5. These results strongly indicate that oestrogen mediates beneficial effects on the cerebral microcirculation and moderates cerebral thrombotic mechanisms in the female rat.     

Progressive recovery of learning during regeneration of a single synapse in the medicinal leech

The leech escape reflex-shortening of the body-can change with nonassociative conditioning, including sensitization, habituation, and dishabituation. Capacity for sensitization, which is an enhancement of the reflex, is lost when a single S-interneuron is ablated, but the reflex response itself remains. In the present experiments, the S-interneuron's axon in the living leech was filled with 6-carboxyfluorescein (6-CF) dye and cut with an argon laser microbeam (lambda = 488 nm). In contrast to sham-operated animals, axotomized preparations did not sensitize, reflecting the key role of the S-cell. By 2 weeks or more, S-cell axons had regenerated and reestablished synapses at their usual locations with neighboring S-cells. By 4 weeks, this restored the ability to sensitize to a level indistinguishable from that of controls, but an intermediate state of recovery was seen from 2-3 weeks after injury-a period not previously examined. The small capacity for sensitization among newly regenerated preparations was significantly lower than in sham controls but appeared higher than in animals whose cut S-cell axon had not regenerated its synapse. The results confirm the crucial role of the S-cell in sensitization. Moreover, full sensitization does not occur immediately upon synapse regeneration.     

Intractable livedoid vasculopathy successfully treated with hyperbaric oxygen

We describe a new method for treating livedoid vasculopathy. The typical presentation of livedoid vasculopathy includes chronic, recurrent painful ulcers, satellite scar-like atrophy and telangiectasia involving the lower extremities. Histologically, these lesions show areas of ulceration and dermal vessel occlusion without frank inflammatory cell infiltration. There is currently no satisfactory therapy available for this disease. Hyperbaric oxygen (HBO) has recently established itself as one of the most effective methods of treating ischaemic wounds, including diabetic ulcers. We used this therapy in two patients whose lesions were resistant to multiple therapeutic modalities. Not only did their ulcers respond rapidly to the HBO therapy, but the disturbing wound pain also resolved at the same time. To our knowledge, this is the first successful trial of HBO therapy in livedoid vasculopathy. We believe this to be a very promising new therapy for livedoid vasculopathy and to be worth further investigation.