In recent years, many compounds having potent antiviral activity in cell culture have been detected and some of these compounds are currently undergoing either preclinical or clinical evaluation. Among these antiviral substances, naturally occurring sulfated polysaccharides and those from synthetic origin are noteworthy. Recently, several controversies over the molecular structures of sulfated polysaccharides, viral glycoproteins, and cell-surface receptors have been resolved, and many aspects of their antiviral activity have been elucidated. It has become clear that the antiviral properties of sulfated polysaccharides are not only a simple function of their charge density and chain length but also their detailed structural features. The in vivo efficacy of these compounds mostly corresponds to their ability to inhibit the attachment of the virion to the host cell surface although in some cases virucidal activity plays an additional role. This review summarizes experimental evidence indicating that sulfated polysaccharides might become increasingly important in drug development for the prevention of sexually transmitted diseases in the near future.

Diets high in fat are associated with an increased risk of prostate cancer, although the molecular mechanism is still unknown. We have previously reported that arachidonic acid, an omega-6 fatty acid common in the Western diet, stimulates proliferation of prostate cancer cells through production of the 5-lipoxygenase metabolite, 5-HETE (5-hydroxyeicosatetraenoic acid). We now show that 5-HETE is also a potent survival factor for human prostate cancer cells. These cells constitutively produce 5-HETE in serum-free medium with no added stimulus. Exogenous arachidonate markedly increases the production of 5-HETE. Inhibition of 5-lipoxygenase by MK886 completely blocks 5-HETE production and induces massive apoptosis in both hormone-responsive (LNCaP) and -nonresponsive (PC3) human prostate cancer cells. This cell death is very rapid: cells treated with MK886 showed mitochondrial permeability transition between 30 and 60 min, externalization of phosphatidylserine within 2 hr, and degradation of DNA to nucleosomal subunits beginning within 2-4 hr posttreatment. Cell death was effectively blocked by the thiol antioxidant, N-acetyl-L-cysteine, but not by androgen, a powerful survival factor for prostate cancer cells. Apoptosis was specific for 5-lipoxygenase-programmed cell death was not observed with inhibitors of 12-lipoxygenase, cyclooxygenase, or cytochrome P450 pathways of arachidonic acid metabolism. Exogenous 5-HETE protects these cells from apoptosis induced by 5-lipoxygenase inhibitors, confirming a critical role of 5-lipoxygenase activity in the survival of these cells. These findings provide a possible molecular mechanism by which dietary fat may influence the progression of prostate cancer.

可下载PDF全文。

【目的】研究地表覆盖对黄土高原旱地冬小麦氮磷钾需求和生理效率的影响，为促进黄土高原旱地冬小麦高效优质生产提供可靠的理论依据和实践经验。【方法】通过田间试验，以裸地休闲为对照，研究地膜覆盖、秸秆覆盖、种植绿肥和秸秆覆盖+种植绿肥对冬小麦籽粒产量、籽粒养分含量、籽粒产量形成和籽粒养分含量形成的氮磷钾需求及生理效率的影响。【结果】地膜覆盖降低了籽粒产量形成的需氮量，提高了籽粒产量形成的氮生理效率，从而使冬小麦籽粒产量显著增加6%；秸秆覆盖降低了地上部吸氮量，使籽粒产量减少7%；种植绿肥和秸秆覆盖+种植绿肥提高了籽粒产量形成的氮磷钾养分需求量、降低了籽粒产量形成的养分生理效率，从而使籽粒产量均减少5%。地膜覆盖提高了籽粒氮含量形成的需氮量，降低了氮生理效率，从而使籽粒含氮量降低8%，地膜覆盖增加了地上部吸钾量，使籽粒含钾量增加4%；秸秆覆盖的籽粒含氮量降低4%，但它的籽粒磷和钾含量分别提高6%和4%，这与降低籽粒磷钾含量形成的养分需求量、提高磷钾生理效率有关；种植绿肥提高了籽粒氮含量形成的氮生理效率，从而使籽粒氮含量增加8%；秸秆覆盖+种植绿肥对籽粒氮和磷含量无显著影响，但籽粒含钾量增加4%，归因于提高了籽粒钾含量形成的钾生理效率。【结论】地膜覆盖降低籽粒产量形成的需氮量，提高籽粒产量形成的氮生理效率，从而提高籽粒产量；但增加了籽粒氮含量形成的需氮量、降低了籽粒氮形成的氮生理效率，不利于籽粒含氮量提高。秸秆覆盖不利于作物养分吸收，从而影响籽粒产量和养分含量形成。种植绿肥和秸秆覆盖+种植绿肥提高了籽粒氮磷钾养分需求量、降低它们的生理效率，从而降低籽粒产量。种植绿肥可提高籽粒氮含量形成的氮生理效率，从而提高籽粒氮含量。因此，旱地小麦生产中为保证籽粒产量和营养品质，需增加地膜覆盖和秸秆覆盖的氮肥用量；夏闲期种植绿肥是旱地土壤培肥的重要措施，但需注意其可能带来的减产风险，应结合区域降水情况因地制宜。

为探明有机物料不同覆盖方式对句容旱地葡萄园土壤理化性质的影响,以5年生阳光玫瑰葡萄园地为研究对象,2018年5月以纯醋糟、醋糟+土壤调理剂、醋糟+黄腐酸钾、醋糟+生物炭、醋糟+微生物菌剂覆盖地表,在有机物料覆盖的基础上再设纯物料覆盖、物料+园艺地布覆盖、物料+无纺布覆盖,以清耕为对照,6个月后对0~20 cm土壤样品分析葡萄园土壤容重、硝态氮、铵态氮、有机质、碱解氮、速效磷和速效钾的变化。结果表明：醋糟配合不同添加剂铺施地表,再辅以无纺布或园艺地布覆盖,均可改善土壤结构,降低土壤容重,提升土壤有机质含量,增加氮磷钾速效养分。醋糟+黄腐酸钾均匀铺施地表与对照比土壤容重下降24.5%,再进行园艺地布覆盖,显著提高土壤有机质含量,与对照比提高147.8%;醋糟配合不同添加剂单独铺施或进行覆盖均提高土壤硝态氮、铵态氮、碱解氮、速效磷及速效钾的含量,其中醋糟+黄腐酸钾覆盖无纺布处理硝态氮含量比对照增加了6倍;醋糟配合不同添加剂单独铺施各处理土壤铵态氮含量高于硝态氮,而醋糟配合不同添加剂覆盖各处理则相反。综合比较各处理,醋糟+黄腐酸钾覆盖无纺布效果最好,建议在句容旱地葡萄园推广使用。

为评价不同覆盖材料在避雨葡萄园中的覆盖效果,通过田间试验,采用秸秆(SM)、透明地膜(WM)、反光膜(RM)、地布(CM)4种材料进行地表连续(2017年11月至2018年10月)覆盖处理,以地表裸露为对照(CK),以夏黑葡萄为试材,研究了避雨葡萄园中不同覆盖材料对土壤微生物特征及葡萄生长与品质的影响。结果表明,与CK相比,地布、透明地膜和反光膜覆盖均可提高0~40 cm土层土壤真菌、细菌数量,降低土壤放线菌数量;4种覆盖材料下土壤微生物生物量碳含量和微生物熵均高于CK,而微生物代谢熵则低于CK;随着生育进程的推进,地布、透明地膜和反光膜覆盖下的土壤有机碳含量呈降低趋势,秸秆覆盖则相反;秸秆和地布覆盖处理可增强土壤呼吸强度,透明地膜和反光膜覆盖处理则降低土壤呼吸强度;4种覆盖材料均可增加葡萄根系活力,促进葡萄叶片及新梢生长,提高葡萄果实内在和外在品质。秸秆覆盖下土壤微生物数量及活性最强,其微生物总量、微生物生物量碳含量、微生物熵及土壤呼吸强度分别较CK显著提高20.27%、51.43%、40.38%、13.52%,而其微生物代谢熵较CK显著降低22.51%;秸秆和反光膜覆盖下葡萄果实品质较佳,二者差异不显著,其果实可溶性固形物分别较CK显著提高14.25%、17.74%。本研究结果为避雨葡萄园覆盖材料的选择提供了理论和实践参考。

为探索不同地表覆盖方式下半干旱地区露地高原夏菜的栽培效果,以松花菜(Brassica oleracea var. botrytis L.)为研究对象,设露地无覆盖(CK1)、地膜覆盖(CK2)、地膜+秸秆行间覆盖(T1)、秸秆行间覆盖(T2)和秸秆全覆盖(T3)5个处理,研究不同地表覆盖方式对松花菜土壤温度、产量和水分利用效率的影响。结果表明,地膜+秸秆行间覆盖与露地无覆盖相比,显著促进了松花菜株高、茎粗和叶面积的增加,但总体与地膜覆盖无显著差异;秸秆行间覆盖和秸秆全覆盖处理抑制了松花菜植株的营养生长。与露地无覆盖相比,地膜+秸秆行间覆盖具有明显的增温效果,且最大增温幅度出现在春茬试验莲座期10 cm土层和秋茬试验苗期5 cm土层,秸秆行间覆盖和秸秆全覆盖处理都不同程度地存在增温和降温双重效应。与地膜覆盖相比,地膜+秸秆行间覆盖处理对土壤温度的调控均能达到地膜覆盖的效果,且在秋茬试验中,地膜+秸秆行间覆盖处理在苗期5 cm和10 cm土层温度分别升高2.5℃和1.8℃,更有利于松花菜幼苗的生长发育,秸秆行间覆盖和秸秆全覆盖处理在两茬试验各生育期、各土层均表现为降温效应,且秸秆全覆盖处理降温效果最明显。与露地无覆盖、地膜覆盖相比,春茬试验,地膜+秸秆行间覆盖处理生物产量分别提高32.3%、2.7%,经济产量分别提高68.9%、4.7%,分别节水29.0%、7.3%,水分利用效率分别提高137.8%、13.1%;秋茬试验,生物产量分别提高4.7%、2.4%,经济产量分别提高27.6%、8.4%,分别节水23.8%、11.1%,水分利用效率分别提高67.2%、21.9%。综上,地膜+秸秆行间覆盖处理具有良好的调温保墒作用,增产增效显著,较地膜覆盖种植在榆中地区更具优越性。