A semi-quantitative direct contact assay using fluorescein diacetate and L929 mouse fibroblasts in monolayer culture

Summary A semi-quantitative procedure is described for measuring cell viability after short-term exposure to a test substance using a monolayer culture. Test substances are placed in direct contact with cell monolayers for various time intervals. The substances are removed and the monolayers are incubated in the presence of fluorescein diacetate. Monolayers are viewed under a fluorescent microscope and the percentage of fluorescing (viable) cells is estimated. The method is suitable for examining cytotoxic effects at short times of exposure and for discriminating between test substances that give similar, low toxicity endpoints in standard 24-h assays.     

Epithelial tissue formation in matrix culture and in histophysiologic gradient culture

Summary Formation of epithelial tissues in culture so that they become facsimiles in their structure of such tissues in nature requires procedures that comply with several spatial imperatives: a) three-dimensional growth; b) histophysiologic conditions that provide, concurrently, gradients of maturation and of diffusion of metabolites; and c) growth as layers of cells without free edges. Many steps have been required in the evolution of these methods. Two systems are described here in sufficient detail to serve as a manual. Three-dimensional growth of masses of epithelial tissue is accomplished in matrix culture using Gelfoam sponge and collagen-coated cellulose sponge. Radial gradient culture, a recent development, provides conditions that comply with the requirements of histophysiologic gradients and of epithelial tissue growth in layers without interruption in their continuity.     

The effect of cigarette smoke on the bovine lens

Smoking has recently been identified from epidemiological studies as a possible cause of cataract but the mechanism involved is not known. Therefore, our laboratory has initiated studies aimed at elucidating these mechanisms. Whole bovine lenses were cultured to examine possible effects of cigarette smoke on amino acid uptake and protein synthesis. Cigarette smoke, filtered to remove nicotine and tar which would not reach the eye in vivo, was bubbled through culture medium. Bovine lenses were incubated in this medium in the presence of [¹⁴C]-leucine for four days. A significant decrease in uptake of [¹⁴C]-leucine and a decrease in protein synthesis were found with smoke treated lenses. This is the first demonstration of an effect of cigarette smoke on the lens. Further work is needed to determine how this metabolic upset is mediated and how it could lead to cataract.     

Suppurative corneal ulceration in Bangladesh

Suppurative keratitis is an important preventable cause of blindness, particularly in the developing world. This study analyses 142 cases of suppurative keratitis referred to Chittagong Eye Infirmary, Bangladesh. Some 53.5% of cases were bacterial and 35.9% were fungal. The five most common pathogens were: Pseudomonas sp. 24%, Streptococcus pneumoniae 17%, Aspergillus sp. 13%, Fusarium sp. 7% and Curvularia sp. 6%. Gram stain and culture results were consistent in 62.6% of cases. Previous antibiotic treatment was a significant factor for failure of culture isolation and less so for Gram stain failure. On Gram stain, 55.9% of pseudomonal cases were missed, but only 2% of fungal cases were missed. Over all, Gram stain had a sensitivity of 62% and positive predictive value of 84% for bacterial cases, and 98% and 94% for fungal cases, respectively. Fungal ulcers were typically filamentous, but an antecedent history of trauma was not common. The most frequent injury was due to rice grains, but the inoculum appeared to be introduced during eye washing with contaminated water. Pseudomonal ulcers occurred most frequently in the monsoon season, and Fusarium cases were seen only in the hot, dry season.     

乡镇中,小学教室噪声卫生防护距离的研究

本文对乡镇中，小学的交通噪声进行了调查研究，结果表明，在９：００～１６：４５时间内，中学的Ｌｅｑ值为８０ｄＢ（Ａ），Ｌ５０为７２ｄＢ（Ａ），小学的Ｌｅｑ值为８０５ｄＢ（Ａ），Ｌ５０为７３ｄＢ（Ａ）。文章还对不同距离的噪怕衰减情况进行统计分析，并制订出乡镇中，小学教室内噪声不超过５０ｄＢ（Ａ）防护距离为１２０米，不超过４５ｄＢ（Ａ）防护距离为２２０米。     

二甲亚砜对人表皮的核酸和蛋白质合成的影响

用体外培养的人的伪表皮作为模型，进行药物毒理学作用的研究，观察了二甲亚砜（ＤＭＳＯ）在不同浓度和不同接触时间条件下，对人的伪表皮细胞脱氧核糖核酸（ＤＮＡ）、核糖核酸（ＲＮＡ）和蛋白质合成的影响：随着接触时间的延长，ＤＮＡ、ＲＮＡ和蛋白质合成均受抑制。低浓度条件下（１％），ＤＮＡ、ＲＮＡ和蛋白质合成增加；在１５～５０％浓度下，ＤＮＡ和蛋白质合成抑制，而ＲＮＡ合成仍增加；在高浓度条件下（７０％～１００％），ＤＮＡ、ＲＮＡ和蛋白质合成均明显抑制。     

山莨菪碱防治甘油所致急性肾功能衰竭的实验研究

在１２９只ＳＤ大鼠的实验中动态观察了山莨菪碱对甘油所致急性肾功能衰竭时不同时期的Ｂｃｒ，ＢＵＮ，ｐＨ病理改变及死亡率的影响，结果表明：山莨菪碱能降低ＡＲＦ第５天大鼠死亡率以及Ｂｃｒ，ＢＵＮ水平。改善病理损害，对ＡＲＦ起到预防及治疗效果，山莨菪碱的预防效果优于治疗效果，预防是ＡＲＦ防治的关键，但山莨菪碱在治疗过程中要引起“冲刷综合征”导致洗脱性酸中毒，应引起注意。     

微量地塞米松与抗病毒药物合用对抗单疱病毒作用的影响

报告在组织培养中地塞米松对单纯疱疹病毒(HSV)的生长繁殖无影响,对无环鸟苷(ACV)和环胞苷(CC)的抗病毒作用亦无干扰。在动物实验中,微量地塞米松[0.001%,常用浓度(0.1%)的百分之一]并不恶化上皮型HSV角膜炎。同时证明有效抗病毒药物的合用,微量地塞米松仍保留有良好的消炎作用,能促进上皮型和实质层型单疱角膜炎的痊愈过程。     

Morphologic characterization of osteoblast-like cell cultures isolated from newborn rat calvaria

Summary Two methods for harvesting osteoblast-like cell populations from newborn (10 days) rat calvaria were compared. The first one consisted in culturing the periosteum-free bones and then trypsinizing the cells on the bone surface. The second one involved the migration of the osteoblasts on glass fragments before trypsinization. Since the plating efficiency, the proportion of alkaline phosphatase-positive cells, the population doubling time, and the calcium deposition were more adequate, the second method was used to further characterize the behavior of the cultures. During the first week of culture, the cells featured shapes similar to those observedin vivo on the surface of periosteum-free calvaria. They formed multilayers and, in the presence of ascorbic acid, synthetized an organic matrix containing exclusively type I collagen. Later, small amounts of type III collagen appeared. The cells were embedded in the matrix and progressively acquired the morphologic phenotype of osteocyte-like cells. The matrix mineralized in the presence of β-glycerophosphate. The technique of dropinoculation (high concentration of cells in a small volume of medium) promoted the multilayer formation and the achievement of large mineralized plates (about 1 cm²) in 3 weeks of culture.