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1.
Kenneth K. H. Chao BS Eric Cheung BS William B. Armstrong MD Brian J. F. Wong MD 《Otolaryngology--head and neck surgery》2002,126(6):593
Objective: The study goal was to compare the laser spot size created using reflective and refractive micromanipulators with a CO2 laser and to determine the sensitivity of spot size to laser power. Study Design and Setting: A CO2 laser and operating microscope (400-mm focal length) was coupled to either a reflective (Cassegrain-like) or refractive micromanipulator. Laser spot size was determined by measuring the region of ablation created by laser irradiation of wood (dry tongue depressors), exposed photographic film, and agar gel using optical micrometry. Laser power varied from 0.5 to 20 W with pulse durations of 0.1 and 0.5 second. Results: The reflective micromanipulator demonstrated overall smaller spot sizes for a given laser power and lower incremental change in spot size with increasing power. The reflective design demonstrated less sensitivity to increases in laser power. Conclusions: Micromanipulator optical design can result in significant differences in laser spot size. The reflective device used in this study demonstrated less sensitivity to increasing laser power. (Otolaryngol Head Neck Surg 2002;126:593-597.) 相似文献
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A B Fulton J Dodge J L Schremser A Armstrong F Lanier W W Dawson T P Williams 《Current eye research》1990,9(12):1211-1216
The content of rhodopsin in the eyes of 15 donors (30 eyes) was determined. Both retinal and pigment epithelial fractions were collected from each globe, extracted using 1% CTAB, and the rhodopsin difference spectrum of each fraction was obtained separately. The total amount of rhodopsin, obtained by summing the amounts recovered from the retinal and PE fractions, ranged from 2.00 to 11.94 (median: 6.40) nmoles/eye. Previously reported mean values of about 3.5 to 4.0 nmoles per retina have been obtained using a variety of methods. The present higher values, perhaps largely dependent on procedural details described herein, appear plausible given the known concentrations of rhodopsin in rod outer segments, rod outer segment volumes, and number of rods in the human retina. 相似文献
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Obstructive and restrictive ventilatory impairment in polyvinylchloride fabrication workers 总被引:1,自引:0,他引:1
P Ernst L De Guire B Armstrong G Thériault 《American journal of industrial medicine》1988,14(3):273-279
Responses to a standardized respiratory symptom questionnaire, spirometry, and cross-shift decreases in lung function between 70 current employees of a polyvinylchloride (PVC) fabrication plant and a control group consisting of 48 men employed in a vegetable packing plant were compared. FEV1/FVC was significantly lower in the PVC workers. Cross-shift drops in Vmax75 of 15% or more were also more prevalent in the exposed group (p = .01). When examining the association between months of work within the exposed workforce and spirometric indices of airway obstruction, no relationship could be demonstrated. However, an inverse dose-response relationship was seen between level of FVC and duration of employment, suggesting a restrictive impairment. While the specific exposures have not been identified, it appears that employment in PVC fabrication may be associated with both obstructive and restrictive ventilatory effects. 相似文献
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H Armstrong 《Canadian Medical Association journal》1997,157(12):1693-1694
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Long-chain fatty acid composition of maternal liver lipids during pregnancy and lactation in the rat: comparison of triglyceride to phospholipid 总被引:1,自引:0,他引:1
The change in long-chain fatty acid composition in maternal liver was studied during pregnancy and lactation in the rat. Maternal liver triglycerides and phospholipids transiently accumulated and were depleted of long-chain fatty acids during pregnancy and lactation. During pregnancy, maternal liver accumulated triglyceride, but triglyceride fatty acid composition changed little. However, maternal liver total phospholipid fatty acid composition changed significantly without a change in the total pool size throughout pregnancy or lactation. The change in composition of (n-3) and (n-6) essential fatty acids in maternal liver triglyceride and total phospholipid occurred in an apparently dyssynchronous manner throughout pregnancy and lactation. 相似文献
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R I Cruz D M Anderson E G Armstrong W R Moyle 《The Journal of clinical endocrinology and metabolism》1987,64(3):433-440
When hCG adsorbs to surfaces, including membranes from tissues that lack specific hCG receptors, it adsorbs with a particular orientation. Some sites on the alpha- and beta-subunits project away from the surface and can be detected with radiolabeled monoclonal antibodies. Other epitopes, which are located on a region on the hormone that presumably contacts the surface, lose their ability to bind antibody. Using antibodies specific for epitopes on hCG which remain exposed and can be detected when the hormone is adsorbed to rat brain homogenates, we found hCG or closely related substances bound to progestational decidual tissues. Immunologically reactive material adsorbed to the decidual tissue increased and decreased in parallel with the serum levels of hCG throughout pregnancy. Binding of labeled monoclonal antibody to substances similar or identical to hCG in other tissues, including placenta and fetal lung, but not red cells, also was identified. Unlike material adsorbed to decidual tissues, receptor-bound hCG was not recognized by any of our alpha-subunit-specific antibodies. This finding suggests either that the adsorbed hormone has a different orientation than receptor-bound hormone or that the adsorbed hormone has dissociated into subunits. These studies represent the first detection of nonreceptor binding of hCG or related molecules to tissues lacking receptors or presumed not to synthesize the hormone. The role of nonreceptor-bound hCG, if any, is unknown. Other than its effects on stimulation of luteal steroidogenesis during early pregnancy, the role of hCG during most of pregnancy has not been determined. Conceivably, the nonreceptor binding we identified is related to a role for hCG in pregnancy that is not associated with an action on the ovarian LH receptor. 相似文献