液晶玻璃毛细管柱色谱和色-质联用分离和鉴定煤焦油馏分

本文用BaCO_3沉积法预处理玻璃毛细管柱,用静态法分别涂以五种液晶固定液(BMBT、BBBT、EPMB、BPBAmB、MPBOB),所得五种液晶玻璃毛细管柱用于分离四种煤焦油馏分——蒽油、洗油、酚油和轻油。发现BBBT和EPMB对蒽油和洗油可得较佳的分离结果;MPBOB毛细管柱可用于分离酚油和轻油。各馏分中分离出的组分数分别为140,100,50,40,流出时间分别为40、30、18和12分钟。各馏分中分离出的组分进行了纯物质对照和色-质联用定性。     

ON and OFF components of the receptive fields have different latencies to diffuse flashes of light in the superior colliculus of golden hamsters

Single unit activities were recorded from the superior colliculus in anesthetized hamsters. ON center and OFF center cells without surround showed short (within 150 ms) and long latency (longer than 150 ms) responses to diffuse flashes of light, respectively; ON and OFF center cells with an antagonistic surround and ON-OFF center cells showed both short and long latency responses. We suggest that the short latency discharges represent the activity on the ON component of the receptive field, while the long latency responses correspond to the OFF component. Thus, latencies of unit response to diffuse flashes of light may provide a useful indication of the existence of ON or OFF components in the receptive field.     

Possible fusimotor innervation to frog muscle spindles

In some muscle spindles located in or near the red area of semitendinosus muscle of the bull frog, a fine motor axon innervates the intracapsular compact zone, without any branches onto the extrafusal muscle fibers. The fine motor axon is 3.9 microns in mean diameter (measured in living axon) and 9.8 m X s-1 in mean conduction velocity at 20 degrees C. A ramp-and-hold stretch during 20 Hz repetitive stimulation of the fine motor axon markedly increased the rate of afferent discharges during static phase. Histochemical studies indicated depletion of glycogen in a compact zone along a small diameter intrafusal muscle fiber of the muscle spindles frozen immediately after tetanic stimulation of the fine motor axon. These results suggest that the fine motor axon is a fusimotor system in the frog muscle spindle.     

UF-100尿沉渣分析仪原理

阐述了UF-100尿细胞全自动分析仪应用流式细胞方法结合荧光染色技术和电阻抗方法检测尿有形成分和化学成分。从检测方法、主要组成部分、检测系统的组成部分及检测信号的产生和处理等几方面介绍了尿细胞的测量原理,最后指出了尿沉渣分析仪对于临床诊治和科研工作具有重要的意义。     

A preliminary investigation into the effect of exposure of photosensitive individuals to light from compact fluorescent lamps

Summary Background  Compact fluorescent lamps (CFLs) are due to replace common incandescent lamps over the next few years. There has been no investigation of the possible effect of this on patients with photosensitive disorders. Objectives  To determine the effect of exposure of photosensitive individuals to light from CFLs. Methods  The spectral emission from a sample of CFLs was measured using a calibrated spectroradiometer. The erythemal response was determined in one normal individual and four photosensitive individuals by direct exposure of the skin to light from a CFL. The susceptibility of a wider group of photosensitive individuals was predicted based on the light dose known to elicit a reaction during phototesting at discrete ultraviolet (UV) wavelengths. Results  CFLs emit UV radiation at wavelengths down to 254 nm. Prolonged exposure of a normal individual’s skin produced erythema. However, an exposure of only 2·5 min at 5 cm elicited marked erythema in one of the abnormally photosensitive patients. Conclusions  CFLs could be a source of harmful UV radiation to photosensitive individuals. Patients with chronic actinic dermatitis are thought to be at greatest risk. The use of a protective envelope is recommended.     

红蓝光治疗痤疮临床疗效观察

目的:探讨红蓝光照射治疗痤疮的临床疗效和安全性。方法:将113例轻、中度痤疮患者分为两组,实验组采用本院自制的克林霉素醇溶液联合红蓝光照射治疗,对照组仅外用本院自制的克林霉素醇溶液治疗。采用痤疮综合分级系统(GAGS)评价治疗前、后疗效。结果:实验组和对照组有效率分别为82.8%和43.6%,两组的治疗有效率存在显著性差异(P<0.01)。GAGS综合分值均较治疗前明显下降(P<0.01),但实验组下降更显著。结论:红蓝光治疗面部轻、中度痤疮安全有效。     

Heat and Photolytic Nitric Oxide are Essential Factors for Light-induced Vascular Tension Changes

. Light induces various vascular tension changes, but these phenomena and their mechanisms remain controversial. We hypothesise that photocontraction results from the thermal effect, and that photorelaxation results from the non-thermal effect of photochemical nitric oxide generation. The isometric tension of a rat aortic ring was measured during laser light irradiation at various wavelengths with constant heat generation. Visible irradiation (458 nm, 514.5 nm) induced either photorelaxation (the tension increment was −20% of the contracted state induced by noradrenaline) or photocontraction (+7.8%); UV irradiation (351 nm) induced only photorelaxation (−41%), and near-IR irradiation (800 nm) produced only photocontraction (+11%). In the vascular tissue, photocontraction increased with deposited light energy, which was proportional to the temperature elevation. Simply heating the vascular tissue also resulted in vasocontraction. Photorelaxation by UV occurred even in the absence of endothelium, and was significantly reduced to 49% of control levels of photorelaxation by the guanylate cyclase inhibitor, methylene blue. Photorelaxation was not reduced by the nitric oxide synthetase inhibitors, N ^ω-monomethyl-l-arginine (l-NMMA) and N ^ω-nitro-l-arginine methyl ester (l-NAME). We conclude that photocontraction is produced by the thermal effect resulting from deposited light energy. Photorelaxation might be induced by endothelium-independent nitric oxide generation, which seems to result from the photochemical effect due to photon energy. Paper received 4 October 1999; accepted after revision 7 February 2000.     

Pascal,ICare and Goldmann applanation tonometry – a comparative study

Purpose: To compare intraocular pressure (IOP) measurements by Pascal, ICare and Goldmann applanation tonometry (GAT), to evaluate the effects of central corneal thickness (CCT) and curvature on IOP measurement and to estimate the intra‐observer variability. Methods: A prospective, single‐centre study of 150 eyes with a wide range of pressures. Six masked IOP measurements/method; corneal thickness and curvature were studied for each eye. GAT was the reference. Results: IOP_Pascal and IOP_ICare correlated with IOP_GAT (r = 0.91, 0.89). Mean ICare measurement exceeded GAT by 2 mmHg. Pascal measured higher than GAT at low IOPs and lower at high IOPs. For every 10 mmHg increase in IOP above 31 mmHg, Pascal measured 2 mmHg lower than GAT and vice versa. CCT was correlated significantly with IOP_GAT (r = 0.23) and IOP_ICare (r = 0.43) but not with IOP_Pascal (P = 0.12). CCT was correlated with age. In a subgroup (>50 years), ICare and the difference between IOP_GAT and IOP_Pascal were affected significantly by the CCT, whereas IOP_GAT and IOP_Pascal were not. Corneal curvature was correlated significantly with IOP_GAT (r = ?0.27) and IOP_Pascal (r = ?0.26) but not with IOP_ICare (P = 0.60). Intra‐observer variability within each set of six measurements was approximately 2 mmHg, irrespective of method. Conclusion: This study showed a reasonable overall correlation and concordance between the IOP obtained with the three instruments. None of the methods were completely independent of the biomechanical properties of the cornea. ICare showed a significant dependency upon CCT, whereas GAT and Pascal showed a significant dependency on corneal curvature. All methods showed intra‐observer variability, which leaves room for further improvement of methods.     

Influence of test parameters on in vitro fracture resistance of post‐endodontic restorations: a structured review

Summary A structured literature review aimed to elucidate test parameters for in vitro testing of post‐endodontic restorations. The literature was digitally searched using MEDLINE, EMBASE, MedPilot and an additional hand search was performed. Two independent researchers assessed the articles in relation to the defined inclusion and exclusion criteria. The literature search revealed 125 abstracts. Sixty‐nine studies were included. Fifty‐seven per cent of the studies investigated maxillary incisors only. The restorative stage as complex of tooth, post, core, and crown and post‐and‐core restored specimens without crowns were used most frequently. Fifty‐nine per cent of the studies used static loading. Only 15% of the studies performed thermocycling and mechanical loading (TCML). However, the number of thermo‐ and load cycles varied. The cross‐head speed of linear loading after TCML ranged from 0·01 to 150 mm min^?1. The reviewed studies were heterogeneous in test design regarding the used test parameters. A methodological standardization of in vitro testing of post‐endodontic restorations is recommended.