Use of diathermy for weeding heterogeneous tissue cultures

Summary Cultures generated from tissues consisting of multiple types of cells are often heterogeneous. Unless the cell type of interest has or can be given some selective growth advantage it may be overgrown by other cells. While developing techniques for the tissue culture of microvascular endothelial cells we evaluated an electrosurgical generator (diathermy) to selectively kill nonendothelail cells. Primary cell cultures were observed at ×100 magnification under phase contrast microscopy and a needle electrode apposed to the cell to be destroyed. A return electrode was constructed by placing a sterile clip in contact with the culture medium. The diathermy power setting controlled the area of lysis. Use of this technique allowed weeding of unwanted cells without damage to endothelial cells, which were able to grow to confluence in pure culture. Dr. Marks receives a Medical Postgraduate Research Scholarship from the National Health and Medical Research Council of Australia. Financial support was received from the Leo Leukaemia and Cancer Research Trust and the Scleroderma Association of New South Wales.     

多西紫杉醇修饰的人工晶体与眼组织相容性分析

目的：探讨经多西紫杉醇修饰的人工晶体对眼组织相容性的影响。方法：按照随机数字表法将32 只日本大耳兔分为两组： 实验组通过手术植入表面经多西紫杉醇修饰处理后的疏水性人工晶体,对照组植入疏水性人工晶体。比较两组人工晶体亲水角、 术后24 小时光耀斑块计数以及人工晶体周围组织炎症浸润数。结果：实验组的亲水角小于对照组,差异有统计学意义（P<0.05）。 实验组光耀斑块计数低于对照组,差异有统计学意义（P<0.05）。实验组家兔人工晶体周围组织炎症浸润计数低于对照组,差异有 统计学意义（P<0.05）。结论：人工晶体表面经多西紫杉醇修饰后,其亲水性、与眼组织的组织相容性增加,且可缓解光耀斑炎症感 染和降低并发症的发生,有重要的临床参考价值。     

Agar and ammonium nitrate influence hyperhydricity,tissue nitrate and total nitrogen content of serviceberry (Amelanchier arborea) shoots in vitro

Shoot tip cultures of Amelanchier arborea Michx.f. were grown on Murashige & Skoog or Woody Plant (WP) medium containing 4.4 M benzyladenine and various concentrations of agar. Increases in agar concentration affected various culture growth variables, decreased culture hyperhydricity and increased tissue nitrate concentration. Additions of ammonium nitrate to cultures grown on WP medium containing 0.4% agar increased all growth variables measured except percent dry weight. Hyperhydricity and tissue nitrate concentration also increase in response to increasing ammonium nitrate in the medium. Since hyperhydricity was shown to be both positively and negatively correlated with increases in tissue nitrate content, it is unlikely that tissue nitrate level alone directly affects hyperhydricity.Abbreviations BA benzyladenine - MS Murashige & Skoog - WP Woody Plant     

烟草耐盐愈伤组织变异体对盐渍的适应性

用组织培养及逐步增加,NaCl浓度的方法,筛选出烟草耐盐愈伤组织变异体。能耐盐(2％ NaCl)的愈伤组织在2％ NaCl中继代29次,再移入无盐培养基中培养11和20代后不能保持提高的耐盐性,分别退化到只耐1.5％与1.0％ NaCl的水平。耐2％ NaCl愈伤组织产生的再生植株自交后代,其萌发种子、幼苗及成长植株均未能表现出耐盐性,说明用选择胁迫方法所筛选出的耐盐细胞系,其耐盐性的提高属于生理适应性。     

鄂东南地区下侏罗统武昌组的双壳类化石

湖北蒲圻车埠和大冶金山店下侏罗统武昌组的双壳类化石可划分为２个组合,武昌组中部Ｑｉｙａｎｇｉａ－Ａｐｓｅｕｄｏｃａｒｄｉｎｉａ组合和武昌组上部Ｈｕｂｅｒｉｃｏｎｃｈａ－Ｋｉｊａ（Ｗｕｃｈａｎｇｅｌｌａ）组合,前者时代为早侏罗世中晚期;后者暂归于早侏罗世最晚期。文中描述２新属１新亚属以及１５新种。     

A Chronobiologic Approach to Ethanol and Acidified Aspirin Injury of the Gastric Mucosa in the Rat

Several models of erosive peptic disease have used drug-induced lesions to examine protective mechanisms of the gastric mucosa. Physiological processes such as acid secretion, motility, or epithelial cell turnover have circadian rhythms which may modulate the susceptibility of the gastric mucosa to injury. In this review are described recent studies which demonstrated that susceptibility to gastric mucosal injury by acidified aspirin and absolute ethanol varied with the phases of the light-dark cycle. Acidified aspirin caused significantly more gastric mucosal lesions when administered early in the light phase compared to administration early in the dark phase. The differences in susceptibility were not altered by pretreatment conditions such as immobilization or length of the fasting period. Absolute ethanol also caused significantly greater gastric mucosal injury when administered in the light than in the dark phase, but this difference was only evident in rats immobilized during the pretreatment fasting period. Further studies are needed to correlate circadian susceptibility to drug-induced gastric mucosal injury with physiological defense mechanisms. Careful attention to circadian timekeeping may allow us to refine therapy to optimize physiological defense mechanisms in the stomach.     

Chemiluminescence Emission during Reactions between Superoxide and Selected Aliphatic and Aromatic Halocarbons in Aprotic Media

The reactions between superoxide free radical anion (.O⁻₂) with the halocarbons CCl₄, CHCl₃, BrCH₂CH₂Br(EDB), decachloro-biphenyl (DCBP), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in dimethyl sulphoxide (DMSO) results in the emission of chemiluminescence (CL). The chemiluminescence reactions are characterized as having biphasic second order kinetics, CL wavelengths between 350 nm and 650 nm, and exhibiting perturbation by chemicals reactive with singlet oxygen. These data suggest that singlet oxygen species are the excited state responsible for the light emissions. Polarographic studies confirm .O⁻₂ consumption and halide release in the reactions, while gas liquid chromatography and NBT reduction demonstrate the decomposition of the halocarbons into products. A chemiluminescent reaction mechanism is proposed involving reductive dehalogenation of the halocarbons and the generation of singlet oxygen. The significance of singlet oxygen generation is discussed with respect to a general mechanism for explaining the rapid initiation of lipid peroxidative membrane damage in halocarbon toxigenicity in animal and plant tissues.     

Tumulduria incomperta and the case for Tommotian trilobites

The enigmatic fossil Tumulduria incomperta Missanhevsky 1969 from the basal Tommotian Stage at 'Dvortsy' on the Aldan River, Siberian Platform, is reinvestigated in light of the report (Fedorov et al. 1979, Dokl. AN SSSR 249) of trilobite remains from the same beds. Comparisons of these supposed trilobites with old and new collections from 'Dvortsy' leave no doubt that they are identical to Tumulduria incomperta. Tumulduria is represented by phosphatic plates with a crude bilateral symmetry, consisting of a central longitudinal rounded ridge flanked by flat lateral portions. They are built of growth lamellae overlapping each other along the axis of symmetry. The surface carries prominent transverse folds and lamellar terminations. There is considerable morphological variation, and the similarity of some specimens to trilobites is only superficial. Tumulduria is interpreted as a bilaterally symmetrical metazoan with a dorsal protective plate; it probably represents a short-lived group that left no descendants.