Platelet-mediated cholesterol accumulation in cultured aortic smooth muscle cells

Cholesterol accumulates within smooth muscle cells and macrophages in atherosclerotic lesions, thereby contributing to the progressive enlargement of these lesions. The mechanism of this cellular accumulation of cholesterol is not known. The possibility that platelets may have a role in the cellular cholesterol accumulation that occurs during atherogenesis was investigated. Incubation of thrombin-activated washed rat platelets (or platelet-free supernatants prepared from thrombin-activated platelets) with cultured rat aortic smooth muscle cells induced cholesteryl ester lipid droplet accumulation within the smooth muscle cells. No cholesteryl ester lipid droplets accumulated when smooth muscle cells were incubated with unactivated platelets. Smooth muscle cell lipid droplet accumulation occurred in the absence of serum lipoproteins and was not inhibited by mevinolin, a drug that blocks cholesterol synthesis. These findings suggest that activated platelets may release cholesterol, which can be accumulated by cells and stored as lipid droplets.     

Computer simulation of the mechanism of interaction of red grape flavonoids with cholesterol

Using methods of computation chemistry, the molecular properties of cholesterol and red grape flavonoids (rutin, catechine, quercetin, resveratrol, epicatechin, epicatechin-gallate) and the mechanism of their interaction are studied. The expediency of the use of flavonoids in food for prevention of cholesterol deposits on the blood vessel walls and atherosclerotic diseases are substantiated.     

Occurrence of High Ozone Concentrations in the Air near Metropolitan Washington

Relatively high concentrations of surface ozone and the indication that ozone is the inciting agent in fleck injury to tobacco were reported previously (1). Considerable interest therefore attaches to weather parameters on the high-ozone days which may throw light on the source and on the physicochemical processes affecting the ozone level. A source in the direction of nearby Washington, D.C., and photochemical production of the oxidant are indicated. Days with appropriate wind direction but low peak ozone concentration are discussed in terms of coexisting weather parameters. The weather ensemble found on highozone days is considered in relation to instances of fleck injury for which peak ozone levels were not measured.     

Ultraviolet radiation levels during the antarctic spring

The decrease in atmospheric ozone over Antarctica during spring implies enhanced levels of ultraviolet (UV) radiation received at the earth's surface. Model calculations show that UV irradiances encountered during the occurrence of an Antarctic "ozone hole" remain less than those typical of a summer solstice at low to middle latitudes. However, the low ozone amounts observed in October 1987 imply biologically effective irradiances for McMurdo Station, Antarctica, that are comparable to or greater than those for the same location at December solstice. Life indigenous to Antarctica thereby experiences a greatly extended period of summerlike UV radiation levels.     

Clonal characteristics of experimentally induced "atherosclerotic" lesions in the hybrid hare

The female hybrid hare (Lepus timidus x Lepus europaeus) is heterozygous for electrophoretically separable, X-linked isoenzymes of glucose-6-phosphate dehydrogenase. The isoenzymes of this animal have been used as cellular markers in the study of the clonal origins of experimentally induced atherosclerotic lesions. Aortic lesions produced in the hybrid hare by feeding cholesterol and injuring the aortic wall with a catheter have been shown to have polyclonal characteristics and in this way are fundamentally different from atherosclerotic fibrous plaques in man.     

Ozone in High Concentrations as Cause of Tobacco Leaf Injury

Evidence obtained by means of rubber strip tests and an ozone recorder indicates the presence of abnormal concentrations of ozone in the atmosphere at times. Excellent correlation was obtained between appearance of "weather fleck" in tobacco and high values for ozone. The great similarity between lesions occurring naturally and those produced by ozone in chambers also indicates that ozone is the probable inciting agent of weather fleck. Varietal differences exist. Study of stomatal action helped to explain variation in leaf injury.     

Growth of continental-scale metro-agro-plexes, regional ozone pollution, and world food production

Three regions of the northern mid-latitudes, the continental-scale metro-agro-plexes, presently dominate global industrial and agricultural productivity. Although these regions cover only 23 percent of the Earth's continents, they account for most of the world's commercial energy consumption, fertilizer use, food-crop production, and food exports. They also account for more than half of the world's atmospheric nitrogen oxide (NOx,) emissions and, as a result, are prone to ground-level ozone (O(3)) pollution during the summer months. On the basis of a global simulation of atmospheric reactive nitrogen compounds, it is estimated that about 10 to 35 percent of the world's grain production may occur in parts of these regions where ozone pollution may reduce crop yields. Exposure to yield-reducing ozone pollution may triple by 2025 if rising anthropogenic NOx emissions are not abated.     

A Reevaluation of the Ozone Budget with HALOE UARS Data: No Evidence for the Ozone Deficit

Recently, additional ozone production mechanisms have been proposed to resolve the ozone deficit problem, which arises from greater ozone destruction than production in several photochemical models of the upper stratosphere and lower mesosphere. A detailed ozone model budget analysis was performed with simultaneous observations of O(3), HCl, H(2)O, CH(4), NO, and NO(2) from the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) under conditions with the strongest photochemical control of ozone. The results indicate that an ozone deficit may not exist. On the contrary, the use of currently recommended photochemical parameters leads to insufficient ozone destruction in the model.     

微生物胆固醇氧化酶的研究进展

胆固醇氧化酶是细菌FAD依赖的黄素蛋白,能够高效地氧化固醇类物质的3β 羟基基团,完成胆固醇代谢的第一步反应。胆固醇氧化酶具有重要的应用价值:在生物催化方面,可用于生产多种固醇类物质; 农业上作为抗虫蛋白,对棉铃虫幼虫具有显著的抗虫效果; 医学上用于检测血清中胆固醇的含量。这些重要的应用促进了人们从不同来源的微生物中分离、纯化胆固醇氧化酶,详细研究其结构与功能的关系。本文综述了产胆固醇氧化酶的微生物种类、酶的类型与结构、酶的催化机理及胆固醇氧化酶的应用等的最新研究进展,并展望了未来的研究重点。      

The dynamics of the stratospheric polar vortex and its relation to springtime ozone depletions

Dramatic springtime depletions of ozone in polar regions require that polar stratospheric air has a high degree of dynamical isolation and extremely cold temperatures necessary for the formation of polar stratospheric clouds. Both of these conditions are produced within the stratospheric winter polar vortex. Recent aircraft missions have provided new information about the structure of polar vortices during winter and their relation to polar ozone depletions. The aircraft data show that gradients of potential vorticity and the concentration of conservative trace species are large at the transition from mid-latitude to polar air. The presence of such sharp gradients at the boundary of polar air implies that the inward mixing of heat and constituents is strongly inhibited and that the perturbed polar stratospheric chemistry associated with the ozone hole is isolated from the rest of the stratosphere until the vortex breaks up in late spring. The overall size of the polar vortex thus limits the maximum areal coverage of the annual polar ozone depletions. Because it appears that this limit has not been reached for the Antarctic depletions, the possibility of future increases in the size of the Antarctic ozone hole is left open. In the Northern Hemisphere, the smaller vortex and the more restricted region of cold temperatures suggest that this region has a smaller theoretical maximum for column ozone depletion, about 40 percent of the currently observed change in the Antarctic ozone column in spring.     

The sensitivity of polar ozone depletion to proposed geoengineering schemes

The large burden of sulfate aerosols injected into the stratosphere by the eruption of Mount Pinatubo in 1991 cooled Earth and enhanced the destruction of polar ozone in the subsequent few years. The continuous injection of sulfur into the stratosphere has been suggested as a "geoengineering" scheme to counteract global warming. We use an empirical relationship between ozone depletion and chlorine activation to estimate how this approach might influence polar ozone. An injection of sulfur large enough to compensate for surface warming caused by the doubling of atmospheric CO2 would strongly increase the extent of Arctic ozone depletion during the present century for cold winters and would cause a considerable delay, between 30 and 70 years, in the expected recovery of the Antarctic ozone hole.     

臭氧在果蔬贮藏保鲜中的应用

概述了臭氧的保鲜机理及发生原理和臭氧在果蔬贮运中的消毒、杀菌和防腐保鲜作用,并指出了臭氧在果蔬保鲜中的应用前景和存在问题。     

臭氧处理海珍品育苗用水效果的初步研究

根据实验所得数据及应用实例，综合分析了臭氧发生器在海珍品育苗中的应用效果，并从理论和实践两方面阐述和论证了它的优越性，为臭氧发生器在第珍品育苗及养成中的普及、推广提供了试验数据和理论依据。     

Changes in stratospheric ozone

The ozone layer in the upper atmosphere is a natural feature of the earth's environment. It performs several important functions, including shielding the earth from damaging solar ultraviolet radiation. Far from being static, ozone concentrations rise and fall under the forces of photochemical production, catalytic chemical destruction, and fluid dynamical transport. Human activities are projected to deplete substantially stratospheric ozone through anthropogenic increases in the global concentrations of key atmospheric chemicals. Human-induced perturbations may be occurring already.     

Eleven-year variation in polar ozone and stratospheric-ion chemistry

A mechanism for producing an 11-year oscillation in ozone over the polar caps is the modulation of galactic cosmic rays by the solar wind. This mechanism has been shown to give the observed phase in ozone oscillations and the correct qualitative dependence on latitude. However, the production of nitrogen atoms from cosmic-ray collisions seems inadequate to account for the ozone amplitude. Negative ions are also produced as a result of cosmic-ray ionization, and negative-ion chemistry may be of importance in the stratosphere. Specifically, NO(x)(-) may go through a catalytic cycle in much the same fashion as NO(x), but with the important distinction that it does not depend on oxygen atoms to complete the cycle. Estimates of the relevant rates of reaction suggest that negative ions may be especially important over the winter polar cap.     

臭氧技术及臭氧植保机械在农业中的应用

随着农药替代技术的发展，以臭氧及臭氧水为代表的臭氧植保技术逐渐在现代生态农业领域得到广泛应用。在介绍臭氧杀虫灭菌机理的基础上，系统阐述了臭氧技术在土壤熏蒸、作物病虫害防治、种子处理、果蔬贮藏、牧场消毒除臭等农业生产领域的应用；在介绍背负式臭氧植保机械、固定式臭氧植保机械、自走式臭氧植保机械、臭氧植保飞机等臭氧相关植保机械的研究及应用现状基础上，剖析了臭氧技术在农业领域的应用优势及制约因素，最后展望了臭氧技术的应用及推广前景。对于进一步研制开发新型臭氧植保机械,并拓展其在农业生产上的应用具有一定的指导意义。     

应用臭氧·液体菌种生产无公害金针菇技术研究

[目的]为了改变金针菇生产周期长、常规消毒药剂残留量大、对人体的刺激严重等缺点。[方法]试验设置臭氧消毒+液体菌种、甲醛消毒+液体菌种、臭氧消毒+固体菌种、甲醛消毒+固体菌种4个组合处理,以甲醛消毒+固体菌种为对照研究比较了臭氧和液体菌种的应用技术。[结果]臭氧+液体菌种组合比对照菌丝长满培养袋时间短10 d左右,产量和产品质量明显提高,污染率下降。[结论]液体菌种和臭氧消毒在金针菇生产上是值得推广的技术。     

臭氧浓度增加对不同敏感型水稻元素吸收与分配的影响

利用新型自然光气体熏蒸平台,以23个水稻品种或株系为供试材料,设置室内对照(10.4 n L·L-1)和臭氧浓度增高(100 n L·L-1)处理,采用组内最小平方和的动态聚类方法,将供试材料按地上部最终生物量对臭氧胁迫的响应从小到大依次分为A、B和C类,研究不同敏感类型水稻营养器官中元素浓度、吸收与分配对臭氧胁迫的响应。臭氧熏蒸使A、B和C三类水稻地上部生物量平均分别下降19%、39%和52%,后两者达极显著水平。与对照相比,臭氧胁迫使稻草中N、P、K、Mg、Mn、Fe、Cu和Zn浓度显著或极显著增加(5%~42%),但对Ca浓度没有影响。与此相反,臭氧熏蒸使稻草中所有测定元素的吸收总量均呈下降趋势,其中N、P、K、Ca、Mg、Cu、Fe和Zn吸收量的降幅均达极显著水平(11%~34%)。多数情形下,茎鞘各元素浓度和吸收量对臭氧胁迫的响应大于叶片。与此相对应,臭氧胁迫使水稻吸收的元素向叶片中分配的比例增加,而向茎鞘分配的比例减少,导致叶片与茎鞘元素吸收量的比值大幅增加(32%~92%)。臭氧与水稻类型的互作对营养器官各元素浓度以及元素在茎叶中的分配比例多无显著影响,但对元素吸收量的影响多达显著或极显著水平,后者表现为臭氧胁迫下敏感水稻元素吸收的受抑程度更大。研究结果表明,与干净空气相比,100 n L·L-1臭氧浓度对水稻营养器官中各元素浓度、吸收和分配多有显著影响,其中元素吸收量对臭氧胁迫的响应明显受水稻敏感程度的影响。     

Solar proton events: stratospheric sources of nitric oxide

The production of nitric oxide (NO) in the stratosphere during each of the solar proton events of November 1960, September 1966, and August 1972 is calculated to have been comparable to or larger than the total average annual production of NO by the action of galactic cosmic rays. It is therefore very important to consider the effect of solar proton events on the temporal and spatial distribution of ozone in the stratosphere. A study of ozone distribution after such events may be particularly important for validating photochemical-diffusion models.     

Erratum

In the Research News article by Gina Kolata "Maleness pinpointed on Y chromosome" (28 Nov., p. 1076), it is said that gametes always induce steroids. In fact, steroids can be produced without gametes. What is constant is that gametes can never be produced without steroids.