氟碳乳剂与右旋糖酐对犬缺血心肌侧支循环供氧的影响

本实验在14只麻醉开胸狗心脏上观察了氟碳乳剂与右旋糖酐稀释血液对心肌耗氧量与供应缺血心肌氧量关系的影响。以左室压力-时间指数(SPTI)作为心肌耗氧量的指标,根据冠脉有效侧支血流量(ECF)、PaO_2和 Hb 浓度计算供应缺血心肌的氧量。实验结果表明,低分子右旋糖酐稀释血液后,SPTI 暂时性轻度增加(稀释后30min 时较对照增加7.1±2.7%,P<0.05,稀释后60min 时增加2.8±1.2%,P>0.05),ECF 明显增多(稀释后30min 时较对照增加58.5±6.1%,P<0.01),缺血区边缘心肌氧供需关系未发生明显变化。氟碳乳剂稀释血液后,SPTI 的变化规律与右旋糖酐稀释后相同(稀释后30min 和60min 时分别较对照增加2.5±0.7%和1.9±0.8%)ECF 和 PaO_2升高(稀释后30min 时分别较对照增加53.9±6.7%和93±8.9%),供应缺血心肌的氧量显著增加,缺血区边缘心肌氧供需矛盾明显改善。     

In vitro and in vivo studies on the mitochondrial import of CBS1, a translational activator of cytochrome b in yeast

Summary Translation of mitochondrial cytochrome b mRNA in yeast is activated by the product of the nuclear gene CBS1. CBS1 encodes a 27 kDa precursor protein, which is cleaved to a 24 kDa mature protein during the import into isolated mitochondria. The sequences required for mitochondrial import reside in the amino-terminal end of the CBS1 precursor. Deletion of the 76 amino-terminal amino acids renders the protein incompetent for mitochondrial import in vitro and non-functional in vivo. When present on a high copy number plasmid and under the control of a strong yeast promoter, biological function can be restored by this truncated derivative. This observation indicates that the CBS1 protein devoid of mitochondrial targeting sequences can enter mitochondria in vivo, possibly due to a bypass of the mitochondrial import system.     

Ultrastructure of the contractile apparatus of rat skeletal muscle embedded in an aqueous medium

The method of tissue embedding in melamine resin was applied to rat skeletal muscle. This method does not require tissue dehydration with organic solvents; only aqueous solutions are used. Electron micrographs of muscles embedded in melamine differ from those embedded in the conventional epoxy resin. In melamine-embedded muscles the actin and myosin filaments appear larger in diameter and subunits can be recognized in cross-sectioned myosin filaments. Within the Z-line, the characteristic patterns described for muscles embedded in epoxy resin are not visible; the spaces between the actin filaments are filled with electron-dense material. This suggests that the Z-line is more compact than could be concluded from epoxy resin-embedded muscle specimens. The M-line appears to be different from what is observed in epoxy-embedded muscle. The membranes appear as several clearly delineated layers. Dehydration rather than the action of the organic solvents per se is the main reason for the differences in the structure of the contractile apparatus between melamine- and epoxy-embedded muscles.     

Cell size of proliferating plant cells increases with temperature: implications in the control of cell division

As chemical reactions related to the regulation of cell proliferation are governed by availability, amount, and concentration of relevant molecules, it has been suggested that cell size is an important factor in the control of cell cycle. We have measured the size of proliferating cells of Allium cepa roots in which growth rate was modified by changes in growth temperature. Two independent cell size parameters have been measured by cytophotometry: cell surface area projection and cell protein content. Average cell sizes of both the proliferating cell population and the subpopulation at the end of mitosis show that cell size increases with growth rate. Calculation of cell size at initiation of DNA replication clearly indicates that average cell size at this point is not growth invariant but positively correlated with growth rate.     

Identification of centromere proteins in different mammalian cells

The characterization of centromeric proteins is facilitated using anti-centromere antibodies present in the sera of patients with the CREST variant of scleroderma. We have employed these sera to determine whether or not those proteins are present in different mammalian species, as well as to study their tissue distribution. Here, we describe the immunofluorescent pattern and the proteins recognized by CREST sera in dividing and resting cells from mouse, rat, swine, hamster, rabbit, and man. In nuclear preparations from cultured cells, thymocytes and spermatozoa from these species, the antigens recognized by CREST sera are proteins of 18 to 20 kDa in all species tested, except in rat. Additionally, two peptides of 80 and 140 kDa were observed in human preparations. In contrast, a 50 kDa peptide is the primary protein detected by the sera in rat nuclei.     

灭幼脲引起两种幼虫表皮组织病变的显微观察

本文研究了灭幼脲引起黄粉(虫甲)(Tenebrio mclitor)和粘虫(Mythimna separata)幼虫的中毒征象和组织学病变.低剂量能引起幼虫蜕皮障碍,但看不到明显的组织学病变.高剂量处理,不仅引起了严重的中毒征象,而且伴有明显的组织学病变:内表皮生长停滞,真皮细胞排列异常,在内表皮和真皮细胞之间出现附加层和球状颗粒.对这些现象进行了较细致的讨论.