套袋对翠冠梨果实货架寿命及生理生化变化的影响

以翠冠梨为试材,研究了套袋对其果实货架寿命及生理生化变化的影响,试验结果表明,套袋能提高果实硬度、Vc含量及SOD活性,抑制细胞膜透性、MDA含量、呼吸速率及乙烯释放的迅速增加,从而有利于延缓果实衰老软化,且双层袋效果更好。     

采后钙处理对梨果实钙的形态和果胶及相关代谢酶类影响的研究

研究了黄花梨经浸钙处理后,果实钙形态转变及果胶含量、多聚半乳糖醛酸酶（PG）和果胶甲酯酶（PME）活力的变化,以及果实硬度的变化。结果表明：浸钙处理的果实总钙含量显著提高,其硬度明显高于对照,且有利于细胞膜透性的保持;梨果实中的NaCl溶性钙最多,其次是水溶性钙,醋酸溶性钙和HCl溶性钙含量较少。在果实贮藏21d时,水溶性钙含量有一个上升的过程,而NaCl溶性钙则有一个下降的过程。浸钙处理后,除醋酸溶性钙外,果实中的水、NaCl和HCl溶性钙含量均有显著的提高。浸钙处理明显抑制了果胶的降解进程与PG的活力,但对PME抑制作用不明显。浸钙处理能提高果实硬度可能与浸钙处理抑制了PG活力有关。     

采后GA3处理对番茄后熟生理的影响

试验采用两种不同浓度GA3处理采后番茄果实,研究GA3对番茄后熟生理的影响。结果表明：不同浓度GA3处理均可有效抑制番茄膜透性增加,降低膜脂过氧化产物丙二醛(MDA)含量,降低超氧化物歧化酶(SOD)和过氧化物酶(POD)活性,从而有效延缓番茄果实后熟衰老,且40mg／kg GA3较20mg／kg GA3处理效果好。GA3对番茄CAT活性无明显作用。     

低温胁迫对麻竹叶片和根系抗性生理指标的影响

采用室内人工低温处理,研究了麻竹(Dendrocalamus latiflorus)叶片及根部质膜透性、丙二醛、可溶性蛋白、可溶性糖含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性和膜脂脂肪酸组成的变化,寻找与竹类植物耐寒性关系最密切的抗性生理指标。结果表明:低温预处理(8℃)15d后,麻竹叶片中可溶性糖、可溶性蛋白含量、POD活性显著提高,根部可溶性糖含量、POD活性显著升高;低温胁迫处理(-2℃)72h后,经低温预处理的麻竹叶片可溶性糖、可溶性蛋白质含量、SOD、POD活性显著高于未经低温预处理,而质膜透性显著低于未经低温预处理,但膜脂过氧化程度显著高于-2℃处理前;经低温预处理的麻竹根部SOD、POD活性及膜脂不饱和脂肪酸相对含量显著高于未经低温预处理,而质膜透性、膜脂过氧化程度较-2℃处理前无显著差异。说明剧烈降温对麻竹生理特征造成严重影响,叶片通过提高可溶性蛋白、可溶性糖含量,维持较高的POD活性以减轻低温伤害;根系则通过维持较高的SOD、POD活性以减轻低温下膜脂过氧化水平,并通过提高膜脂不饱和脂肪酸比例降低质膜透性来抵御低温对膜的伤害。     

钙素和水分亏缺对黄瓜叶片细胞质膜透性的影响

用控制溶液的钙量[加或不加Ca(NO_3)_2]和渗透势(加聚乙二醇6000,202 g/L)的方法,研究了钙素和水分亏缺对黄瓜叶片细胞质膜透性的影响。结果表明:在渗透胁迫下,正常供钙的黄瓜叶片相对含水量(RWC)和膜透性变化较小、MDA增加不显著、SOD活性无明显改变;缺钙植株叶片的RWC随渗透胁迫处理线性下降,膜透性显著增大、MDA含量迅速提高、SOD活性也升高。在正常水分供应下,与供钙植株相比,缺钙植株SOD活性和MDA含量均较高,但RWC和膜透性无差异。在水分胁迫下,缺钙植株MDA和质膜透性与ΔRWC以及MDA与质膜透性之间均呈正相关。这些结果表明在水分胁迫下,缺钙处理叶片保水能力降低,使受害加重;同时,细胞质膜的稳定性降低。膜透性改变可能与在水分胁迫下体内的膜脂过氧化反应密切相关,即缺钙加速了膜脂过氧化反应,从而损害了质膜结构。     

采后荔枝果实中氧化和过氧化作用的变化

采后的荔枝（Litchi chinensts)果实的果皮和果汁中的抗坏血酸及果汁的谷胱甘肽含量逐渐下降,果皮的谷胱甘肽甘肽含量先增多（采后3天）接着减少,超氧化物歧化酶活性随采后时间加长而降低,膜脂过氧化产物丙二醛及过氧化物酶活性显著增高,采收7天后果皮中丙二醛含量增加2倍,过氧化物酶活性增高6－7倍,超氧物歧化酶活性只为原来的44％,内源清除活性氧能力的减弱与膜脂过氧化产物的积累表明,荔枝果实的衰老与活性氧的伤害有关,过氧化物酶活性增高可作为果实衰老的一个指标。     

采后荔枝果实中氧化和过氧化作用的变化

采后的荔枝（Litchi chinensts)果实的果皮和果汁中的抗坏血酸及果汁的谷胱甘肽含量逐渐下降,果皮的谷胱甘肽甘肽含量先增多（采后3天）接着减少,超氧化物歧化酶活性随采后时间加长而降低,膜脂过氧化产物丙二醛及过氧化物酶活性显著增高,采收7天后果皮中丙二醛含量增加2倍,过氧化物酶活性增高6－7倍,超氧物歧化酶活性只为原来的44％,内源清除活性氧能力的减弱与膜脂过氧化产物的积累表明,荔枝果实的衰老与活性氧的伤害有关,过氧化物酶活性增高可作为果实衰老的一个指标。     

GA1处理采后油桃果实膜脂过氧化的影响

采后GA3处理“阿姆肯”油桃果实（Prunus Persica (L.)nectarine.cv.‘armking’),降低了果实中过氧化氢（H2O2）积累和膜脂过氧化产物丙二醛（MDA）含量,显著提高了活性氧清除酶过氧化氢酶（CAT）和抗氧化剂谷胱甘肽（GSH）的含量,降低了果实衰老期间的膜脂过氧化,对“阿姆肯”油桃有一定保鲜效果。     

采前喷施草酸对芒果果实细胞钙含量和分布的影响

利用焦锑酸钾沉淀-透射电子显微镜观察的方法, 观测了采前喷施草酸或钙后采收期芒果(Mangifera indica)果实细胞钙含量和分布情况, 探讨钙含量和分布变化对果实成熟和衰老的影响。结果表明, 与对照相比, 采前经草酸或钙处理的果实果皮和果肉细胞排列较规则且致密, 淀粉粒分布较多。采前草酸或钙处理均能显著提高芒果果皮和外果肉组织的钙含量;疏松结合态钙均匀分布在果皮和果肉细胞的细胞壁、细胞膜、液泡膜和质体中, 并在液泡内堆积; 而对照果实的液泡膜模糊, 钙颗粒较少。实验证明采前喷施草酸或钙能维持果实细胞的形态, 提高果实细胞的钙含量, 影响钙的分布, 有利于保持果实的硬度并可增加果实营养。     

采前喷施草酸对芒果果实细胞钙含量和分布的影响

利用焦锑酸钾沉淀-透射电子显微镜观察的方法, 观测了采前喷施草酸或钙后采收期芒果（Mangifera indica）果实细胞钙含量和分布情况, 探讨钙含量和分布变化对果实成熟和衰老的影响。结果表明, 与对照相比, 采前经草酸或钙处理的果实果皮和果肉细胞排列较规则且致密, 淀粉粒分布较多。采前草酸或钙处理均能显著提高芒果果皮和外果肉组织的钙含量;疏松结合态钙均匀分布在果皮和果肉细胞的细胞壁、细胞膜、液泡膜和质体中, 并在液泡内堆积; 而对照果实的液泡膜模糊, 钙颗粒较少。实验证明采前喷施草酸或钙能维持果实细胞的形态, 提高果实细胞的钙含量, 影响钙的分布, 有利于保持果实的硬度并可增加果实营养。     

Exercise-induced hormone responses in girls at different stages of sexual maturation

The dependence of exercise-induced hormone responses on sexual maturation was tested in a 3-year longitudinal experiment on 34 girls (aged 11–12 years at the beginning). Sexual maturation was evaluated by Tanners five-stage scale. Children cycled for 20-min at 60% maximal oxygen uptake once a year. Cortisol, insulin, growth hormone, β-oestradiol, progesterone and testosterone concentrations in venous blood were determined by radioimmunoassay procedures. Basal concentrations of growth hormone increased and of cortisol decreased when breast stage III was reached. Reaching breast stage IV was associated with an increase in basal concentrations of β-oestradiol, progesterone and testosterone. The exercise induced significant increases in concentrations of cortisol, growth hormone and β-oestradiol and a decrease in insulin concentration. At breast stage III the increase in cortisol concentration was to a lower level [467 (SEM 42) vs 567 (SEM 46)nmol · l⁻¹] and growth hormone concentration to a higher level [29.4 (SEM 0.5) vs 12.8 (SEM 0.4)ng · ml⁻¹], while the fall in insulin concentration was less pronounced [postexercise level 10.6 (SEM 0.9) vs 7.8 (SEM 0.8)mU · l⁻¹] than in stage II. The magnitude of the cortisol response was reduced in the last stage of breast development (+42.1% vs +55.5% at stage II, +66.2% at stage III, and +50.0% at stage IV). The magnitude of β-oestradiol response was the lowest in breast stage IV (+15.8%) and the highest at stage V (+41.1%). The progesterone response became significant at stage IV and testosterone response at stage V. In conclusion, we found that reaching breast stage III was associated with altered responses of cortisol, insulin and growth hormone concentrations while the responses of the sex hormone concentrations became pronounced in the last stages of sexual maturation. Accepted: 17 September 1997     

Photoprotection of phytochrome

High-fluence-rate white light is shown to retard the degradation of phytochrome in etiolated seedlings of four different species: Amaranthus caudatus, Phaseolus radiatus (mung bean), Pisum sativum (garden pea), and Avena sativa (oat). In Amaranthus, a high photon fluence rate (approx. 1000 mol · m^-2 · s^-1) preserved nearly 50% of the total phytochrome over a period of 5 h; at 3 mol · m^-2 · s^-1, less than 8% remained over the same period. Kinetics of the loss of total phytochrome could be interpreted in terms of two populations, one with rapid, and one with slow, turnover rates. A log-linear relationship between fluence rate and proportion of slowly degrading phytochrome was observed; a similar relationship between fluence rate and the amount of phytochrome remaining after a 5-h light treatment was seen. In mung bean, although two populations of differing degradation rates were not resolvable, a similar log-linear relationship between fluence rate and amount remaining after a standard light treatment was evident. Detailed kinetic analyses were not performed with peas and oats, but comparisons of low and high fluence rates demonstrated that photoprotection was similarly effective in these species. In Amaranthus, transfer from high to low fluence rate was accompanied by a rapid increase in degradation rate, indicating that the retarding effect of high-fluence-rate light is not a consequence of the disablement of the degradative machinery.Immunochemical analyses confirmed the existence of photoprotection in all four species, and allowed the extension of the observations to periods of light treatment during which substantial chlorophyll production occurred. Considerable photoprotection was observed in oat seedlings exposed to summer sunlight. These results are interpreted in terms of the accumulation under high fluence rates of photoconversion intermediates not available to the degradative machinery which is specific for the far-red-absorbing form of phytochrome.Abbreviations Pfr far-red absorbing form of phytochrome - Po amount of phytochrome measured at time zero - Pt amount of phytochrome measured at time t - Ptot total phytochrome - WL white light     

论＂医德＂的基本范畴

医德是医疗卫生领域精神文明建设的重要部分,也是调整医务人员与病人、医务人员之间以及与社会之间关系的行为准则。医德范畴是指人们对现代医务人员职业道德和医患关系的总结,它不仅概括了医生所应履行的职责义务,而且反映着一段时间内医患关系的本质。本文通过对医德范畴内,医生的权利和义务、责任和良心、功力和荣誉、审慎和保密四类问题的阐述,探讨当下医生在工作中应该保持何种心态,如何与患者进行沟通,以期更好地提供医疗服务。     

Regulation of cellular immune responses by selenium

Selenium (Se) is an essential nutritional factor that affects the development and expression of cell-mediated immune responses directed toward malignant cells. These studies have shown that dietary (2 ppm for 8 wk) or in in vitro (1×10⁻⁷ M) supplementation with Se (as sodium selenite) results in a significant enhancement of the proliferative responses of spleen lymphocytes from C57B1/6J mice in response to stimulation with mitogen or antigen. Se deficiency (0.02 ppm for 8 wk) had the opposite effect. The alterations in the ability of the cells to proliferate, which occurred in the absence of changes in the endogenous levels of interleukin-2 (II₂) or interleukin 1, were apparently related to the ability of Se to alter the kinetics of expression of high-affinity Il₂ receptors on the surface of activated lymphocytes. This resulted in an enhanced or delayed clonal expansion of the cells, and in an increased or decreased frequency of cytotoxic cells within a given cell population. The changes in tumor cytotoxicity were paralleled by changes in the amounts of lymphotoxin produced by the activated cells. Dietary Se modulations had a comparable effect on macrophage-mediated tumor cytodestruction. The results also suggested that Se exerts its effect 8–24 h after stimulation, and that it most likely affects processes in the cytoplasmic and/or nuclear compartments of activated lymphocytes.     

Responses of soil bacterial and fungal communities to reciprocal transfers of soil between adjacent coniferous forest and meadow vegetation in the Cascade Mountains of Oregon

Little information exists on the responses of soil fungal and bacterial communities in high elevation coniferous forest/open meadow ecosystems of the northwest United States of America to treatments that impact vegetation and soil conditions. An experiment was conducted in which soil cores were reciprocally transplanted between immediately adjacent forests and meadows at two high elevation (∼1,600 m) sites (Carpenter and Lookout) in the H.J. Andrews Experimental Forest located in the Cascade Mountains of Oregon. Half of the cores were placed in PVC pipe (closed) to prevent new root colonization, whereas the other cores were placed in mesh bags (open) to allow recolonization by fine roots. A duplicate set of open and closed soil cores was not transferred between sites and was incubated in place. After 2 year, soil cores were removed and changes in fungal and bacterial biomasses determined using light microscopy, and changes in microbial community composition determined by PLFA analysis, and by length heterogeneity PCR of the internal transcribed spacer region of fungal ribosomal DNA. At both sites soil microbial community structures had responded to treatments after 2 year of incubation. At Carpenter, both fungal and bacterial community structures of forest soil changed significantly in response to transfer from forest to meadow, with the shift in fungal community structure being accompanied by a significant decrease in the PLFA biomarker of fungal biomass,18:2ω6,9. At Lookout, both fungal and bacterial community structures of forest soil changed significantly in response to open versus closed core treatments, with the shift in the fungal community being accompanied by a significant decrease in the 18:2ω6,9 content of closed cores, and the shift in the bacterial community structure being accompanied by a significant increase in bacterial biomass of closed cores. At both sites, fungal community structures of meadow soils changed differently between open and closed cores in response to transfer to forest, and were accompanied by increases in the18:2ω6,9 content of open cores. Although there were no significant treatment effects on the bacterial community structure of meadow soil at either site, bacterial biomass was significantly higher in closed versus open cores regardless of transfer.     

Comparative study of major lipid constituents in human and monkey aorta

The contents of total lipids, phospholipids, cholesterol, triglyceride and free fatty acid in intima and media of thoracic and abdominal segments of aorta from normal human subjects and rhesus monkeys were determined. An increase in total lipids in intima as compared to that of media was noted in both species. A comparison of lipid contents of thoracic and abdominal segments from both species revealed that abdominal segment contained significantly greater lipid. Further, human thoracic and abdominal aortic intima and media had higher content of cholesterol as compared to that of monkey aorta. The differences in lipid profile in aorta of these two species have been highlighted to provide a clue with respect to the differences in the prevalence and morphology of atherosclerosis as seen in monkey and man.     

食用菌产业发展需要科学研究的强力支撑

我国是世界食用菌产业大国,产量占全球总产80%,拥有全球最多的食用菌基础科学和应用技术研究者,近年来在这两个领域都取得了显著成绩,但仍远远不能满足产业发展的科学需求。我国食用菌产业的发展需要科学研究的强力支持。本专刊集结了食用菌的资源与利用、遗传育种、组学分析、生理栽培、加工技术、活性成分、保健功效评价等方面的论文共计32篇。本刊论文还涉及了食用菌与病原菌的互作研究、野生菌的种类产地鉴定等方面的研究。     

关于苏北地区某三甲医院进口与国产医疗设备和耗材使用情况及反馈的研究．

目的：初步了解了进口与国产医疗设备与耗材的发展状况和使用反馈情况,并对国内医疗设备与耗材行业的发展提供合理化建议。方法：通过对苏北地区某三级甲等医院设备科工作人员、医生、护士长、患者及患者家属进行调研或访谈,并以调研和访谈的统计结果为依据得出结论并提出建议。结果：技术成熟的中小型医疗设备或耗材,从质量、价格等因素综合考虑,国内产品优于进口产品,一定程度上得到了医务人员和消费者的认可。在高端大中型医疗设备与耗材方面,进口产品具有较大的技术优势。结论：国内医疗设备生产企业应当积极开展研发工作,提高产品的技术含量与质量,巩固自身在中小型医疗设备与耗材方面的优势,并努力在高端大中型医疗设备与耗材方面取得突破。     

Electroporative deformation of salt filled lipid vesicles

Membrane electroporation, vesicle shape deformation and aggregation of small, NaCl-filled lipid vesicles (of radius a = 50 nm) in DC electric fields was characterized using conductometric and turbidimetrical data. At pulse durations t_E≤ 55 ± 5 ms the increase in the conductivity of the vesicle suspension is due to the field-induced efflux of electrolyte through membrane electropores. Membrane electroporation and Maxwell stress on the vesicle membrane lead to vesicle elongation concomitant with small volume reduction (up to 0.6% in an electric field of E = 1 MV m^–1). At t_E > 55 ± 5 ms, further increases in the conductivity and the optical density suggest electroaggregation and electrofusion of vesicles. The conductivity changes after the electric pulse termination reflect salt ion efflux through slowly resealing electropores. The analysis of the volume reduction kinetics yields the bending rigidity κ = (4.1 ± 0.3) ⋅ 10^–20 J of the vesicle membrane. If the flow of Na⁺ and Cl^– ions from the vesicle interior is treated in terms of Hagen-Poiseuille's equation, the number of permeable electropores is N = 39 per vesicle with mean pore radius r_p = 0.85 ± 0.05 nm at E = 1 MVm^–1 and t_E≤ 55 ± 5 ms. The turbidimetric and conductometric data suggest that small lipid vesicles (a ≤ 50 nm) are not associated with extensive membrane thermal undulations or superstructures. In particular with respect to membrane curvature, the vesicle results are suggestive for the design and optimization of electroporative delivery of drugs and genes to cell tissue at small field strengths (≤1 MVm^–1) and large pulse durations (≤100 ms). Received: 8 July 1997 / Accepted: 15 September 1997