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1.
Sticholysin I (St I) is a pore-forming toxin (PFT) produced by the Caribbean Sea anemone Stichodactyla helianthus belonging to the actinoporin protein family, a unique class of eukaryotic PFT exclusively found in sea anemones. As for actinoporins, it has been proposed that the presence of sphingomyelin (SM) and the coexistence of lipid phases increase binding to the target membrane. However, little is known about the role of membrane structure and dynamics (phase state, fluidity, presence of lipid domains) on actinoporins' activity or which regions of the membrane are the most favorable platforms for protein insertion. To gain insight into the role of SM on the interaction of St I to lipid membranes we studied their binding to monolayers of phosphatidylcholine (PC) and SM in different proportions. Additionally, the effect of acyl chain length and unsaturation, two features related to membrane fluidity, was evaluated on St I binding to monolayers. This study revealed that St I binds and penetrates preferentially and with a faster kinetic to liquid-expanded films with high lateral mobility and moderately enriched in SM. A high content of SM induces a lower lateral diffusion and/or liquid-condensed phases, which hinder St I binding and penetration to the lipid monolayer. Furthermore, the presence of lipid domain borders does not appear as an important factor for St I binding to the lipid monolayer.  相似文献   
2.
目的:研究糖尿病肾病(DN)患者血浆中性粒细胞明胶酶相关脂质运载蛋白(NGAL)和血清胱抑素C(CysC)水平变化,分析其对DN的早期诊断价值。方法:选取160例糖尿病(DM)患者按尿微量白蛋白排泄率(UAER)分为DN前期组58例(A组),DN早期组52例(B组)及DN临床组50例(C组),同期选择健康体检者61例为对照组(D组)。比较四组受试者血中NGAL、CysC、尿素氮(BUN)和血肌酐(CREA),及尿中微量清蛋白(UMA)水平的差异,分析血NGAL、CysC与UMA之间的相关关系。结果:(1)A、B、C组受试者NGAL、CysC及UMA水平显著高于D组,且CBA,差异均有统计学意义(P0.05);C组BUN和CREA水平均明显高于A、B、D三组,差异均有统计学意义(P0.05),而A、B组较D组均无统计学差异(P0.05)。(2)血NGAL、CysC与尿UMA均存在正相关关系(r=0.59,0.64;P均0.05)。结论:DN早期患者血浆NGAL与血清CysC水平显著升高,且二者均与尿UMA水平存在正相关关系,可作为评价肾脏损害程度及DN早期诊断的较敏感的生物学标志物,临床推荐应用。  相似文献   
3.
目的:探究患者降钙素原(PCT)和N端前体脑利钠肽(NT-proBNP)水平在评价脓毒血症患者生存状况的预测价值。方法:本研究于2013年6月~2015年6月期间,选择在我院治疗的脓毒血症患者81例为研究对象,根据患者纳入研究后1个月的生存状况,将所有研究对象分为存活组(55例)和死亡组(26例)。分别测定患者PCT和NT-proBNP水平,并记录患者急性生理与慢性健康状况(APACHEII)评分,通过ROC曲线探究PCT、NT-proBNP对患者生存预后评估的价值。结果:死亡组患者PCT水平及APACHEII评分均显著高于存活组,NT-pro BNP水平显著低于存活组患者(P0.05);PCT与APACHEII评分存在正相关关系(r=0.311;P0.05);NT-pro BNP水平与APACHEII评分存在负相关关系(r=-0.289;P0.05);ROC曲线显示PCT、NT-proBNP水平预测患者生存状况的敏感性(86.23%、82.01%)及特异性(80.89%、87.39%)均较高。结论:脓毒血症患者血清PCT与NT-proBNP水平在预测患者病情严重程度及生存状况方面具有重要价值。  相似文献   
4.
目的:探讨冠心病患者静息心率与血小板活性的相关研究。方法:选择2013年1月至2014年9月于我院住院患者474例,按静息心率快慢分为三组,心率70 bmp为第一组(Q1)150例,心率位于70~85 bmp为第二组(Q2)265例,心率85 bmp为第三组(Q3)59例,三组患者均于病情稳定时行血栓弹力图(TEG)中MA值检测,同时随访3个月,观察和比较三组患者MA值变化及预后。结果:三组患者MA值分别为61.16±7.29 mm、62.02±7.46 mm、65.32±6.56 mm,第三组患者MA值与第一组或第二组患者MA值比较差异均存在统计学意义(P0.05),通过血栓弹力图检测三组经花生四烯酸(AA)途径的血小板抑制率和经二磷酸腺苷(ADP)途径的血小板抑制率发现,静息心率高低与抗血小板药物作用疗效无相关关系(P0.05)。随访3个月,三组患者心绞痛、再住院、脑血管病及死亡的总发生率分别为28%、28.68%、40.67%。结论:冠心病患者静息心率越快,MA值越大即血小板活性越高,静息心率的高低与抗血小板药物作用疗效无关。  相似文献   
5.
6.
1. Plant–plant communication has been found to affect interactions between herbivores and plants in several model systems. In these systems, herbivore‐induced volatile chemical cues are emitted and perceived by other plants (receivers), which subsequently change their defensive phenotypes. Most studies have focused on how the effects of volatile cues affect plant damage, whereas herbivore performance has rarely been examined. 2. In this study, it is shown that plant–plant communication between willows reduced the growth rate, feeding rate, and conversion efficiency of some individuals but not others of a generalist caterpillar, Orgyia vetusta. 3. Using a paired, no‐choice trial design, there was substantial variation between caterpillar individuals in their response to willows that had been induced with a volatile plant–plant cue. This variation was explained by feeding parameters of the individual herbivores. Individuals behaved similarly when fed induced and non‐induced willow leaves. Specifically, growth rates of caterpillars that grew rapidly on non‐induced willow leaves were negatively affected by plant–plant cues, but growth rates of caterpillars that grew slowly on non‐induced willow leaves were not affected by the responses to volatiles from neighbouring willows. 4. Induction by volatile plant–plant cues reduced the growth rates of those individual herbivores that caused the greatest damage to willow, but had little effect on weak growers.  相似文献   
7.
We report an analysis of the effect of two different times of day (noon and dusk), body weight and sex on the oxygen consumption rate (OCR) of the freshwater crabs Trichodactylus kensleyi (Trichodactylidae), Aegla singularis and A. platensis (Aeglidae) in their natural environment. Both families are sympatric in the studied locations, with a co-occurrence found between T. kensleyi and A. singularis or T. kensleyi and A. platensis. The mean OCR was highest in A. singularis and lowest in A. platensis. The OCR was higher in Aegla species at noon, and Trichodactylus consumed more oxygen at dusk. In aeglids, there was no difference in oxygen consumption between noon and dusk. T. kensleyi exhibited statistically significant differences in the OCR between noon and dusk. The oxygen uptake of all three species analysed was not influenced by the sex of the individual but varied according to the animals’ weight. The families evaluated share some biological and ecological characteristics, such as diet and habitats, but the strategies used in the regulation of gas exchange at different times of the day were different. Environmental factors may be influencing the oxygen consumption of each morphotype differently.  相似文献   
8.
This study investigated whether itch induced by intra-epidermal histamine is subjected to modulation by a standardized conditioned pain modulation (CPM) paradigm in 24 healthy volunteers. CPM was induced by computer-controlled cuff pressure algometry and histamine was introduced to the volar forearm by skin prick test punctures. Moreover, neurogenic inflammation and wheal reactions induced by histamine and autonomic nervous system responses (heart rate variability and skin conductance) were monitored. CPM did not modulate the intensity of histamine-induced itch suggesting that pruriceptive signaling is not inhibited by pain-recruited endogenous modulation, however, CPM was found to aggravate histamine-induced neurogenic inflammation, likely facilitated by efferent sympathetic fibers.  相似文献   
9.
J. P. Hill  R. L. Malmberg 《Planta》1991,185(4):472-478
The growth of vegetative and reproductive shoots of Nicotiana tabacum L. cv. Xanthi is analyzed with the plastochron index to estimate the relationship between corolla growth and time. The plastochron of leaves 9 through 20 declines steadily at each successive node. The flower plastochron increases steadily during the growth of an individual cyme, with the most distal flower to open having the longest plastochron. Variation in the flower plastochron is the result of variation in the rate of flower initiation, not the growth rate of individual flowers. The corolla has an extended phase of approximately constant relative growth in length (between 0.2 · d–1 and 0.3 · d–1) until a peak of growth (0.5 · d–1) 2–3 d before anthesis. Corollas also have periodic peaks and troughs of growth that are low in amplitude (0.1 · d–1), but persist throughout most of corolla development. The pattern of corolla expansion contrasts strongly with earlier reports of the pattern of tobacco leaf growth.Abbreviations PI plastochron index - PR plastochron ratio - RGR relative growth rate in length The authors thank: Drs. T. Sage and E.G. Williams for the considerable time and space they invested; the members of Dr. R. Wyatt's laboratory for allowing us to use their computer facilities; A. Tull and M. Smith for their care taken in the green-house. This research was supported by U.S. Department of Agriculture grant GAM-89-01056 and by National Science Foundation grant DCB-87-15799.  相似文献   
10.
The high water content of the intervertebral disc is essential to its load bearing function and viscoelastic mechanical behavior. One of the primary biochemical changes associated with disc degeneration is the loss of proteoglycans, which leads to tissue dehydration. While previous studies have reported the effects of in vivo degeneration on annulus fibrosus (AF) failure mechanics, the independent role of water remains unclear, as does the tissue’s rate-dependent failure response. Our first objective was to determine the effect of loading rate on AF failure properties in tension; our second objective was to quantify the effect of water content on failure properties. Water content was altered through enzymatic digestion of glycosaminoglycans (GAGs) and through osmotic loading. Bovine AF specimens were tested monotonically to failure along the circumferential direction at 0.00697%/s or 6.97%/s. Increased loading rate resulted in a ∼50% increase in linear-region modulus, failure stress, and strain energy density across all treatment groups (p < 0.001). Decreased GAG and water contents resulted in decreased modulus, failure stress, and strain energy density; however, these differences were only observed at the low loading rate (p < 0.05; no changes at high rate). Osmotic loading was used to evaluate the effect of hydration independently from GAG composition, resulting in similar decreases in water content, modulus, and strain energy density. This suggests that hydration is essential for maintaining tissue stiffness and energy absorption capacity, rather than strength, and that GAGs contribute to tissue strength independently from mediating water content.  相似文献   
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