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1.
目的:研究口服葡萄糖-电解质液(GES)对大鼠40%血容量失血时肠组织缺血性损伤的影响。方法:雄性SD大鼠,用氯胺酮-速眠新Ⅱ肌注复合麻醉后,行右颈动脉插管。随机分为3组(n=24):GES对照组(GES),失血性休克组(HS)和失血性休克+口服GES液组(HS+GES)。GES组:不放血,手术后口服GES;HS和HS+GES组按全身血容量的40%分两次间隔15min放血制作失血性休克模型。HS+GES组于失血后0.5h、1h和6h分3次给予3倍失血量的GES灌胃。用激光多谱勒血流仪测定失血后2h、4h和24h肠组织血流量(IBF)后,处死动物后取肠组织检测二胺氧化酶(DAO)和Na^+-K^+-ATP酶活性,测定肠组织含水率(WG),并做病理学检查。结果:HS+GES组IBF和Na-K-ATP酶活性均显著高于HS组(P〈0.05),但显著低于GES组(P〈0.05);失血各组肠WG显著高于GES组(P〈0.05),24h时HS+GES组WG显著低于HS组(P〈0.05);HS+GES组24hDAO活性均显著高于HS组(P〈0.05),但显著低于GES组(P〈0.05);失血后24h病理检查HS+GES组肠组织水肿和充血改变比HS组明显减轻。结论:口服GES液能显著增加大鼠失血性休克早期IBF,提高Na^+-K^+-ATP酶和DAO活性,减轻肠组织水肿和缺血性损伤。  相似文献   
2.
Abstract

Despite many reports concerning processing of ancient soft tissues, scant attention has been paid to optimizing procedures for processing soft tissues that have been altered by taphonomic processes. To determine the best procedures, we investigated the rehydration solution, time of exposure to the solutions, fixative solution and exposure to heat. Processes were evaluated based on the minimum section thickness, degree of tissue fragmentation, definition of tissue architecture and penetration of stains. We found that in desiccated samples, tissue architecture was optimized by using Ruffer's solution for rehydration and Schaffer's solution as fixative, because these tissues require water restoration within the tissues due to their compacted character. Heating enhanced penetration of dyes in these specimens, which improved diagnosis. Saponified tissues that had suffered extensive decomposition were more labile and required slow water uptake. The best histological sections were obtained using Sandison's solution followed by fixation with formaldehyde and avoiding heat. To obtain the best results with paleohistological specimens, the procedure must be determined by the condition of the sample and by accounting for the nature of its damage.  相似文献   
3.
Firon N  Nepi M  Pacini E 《Annals of botany》2012,109(7):1201-1214

Background

The male gametophyte developmental programme can be divided into five phases which differ in relation to the environment and pollen hydration state: (1) pollen develops inside the anther immersed in locular fluid, which conveys substances from the mother plant – the microsporogenesis phase; (2) locular fluid disappears by reabsorption and/or evaporation before the anther opens and the maturing pollen grains undergo dehydration – the dehydration phase; (3) the anther opens and pollen may be dispersed immediately, or be held by, for example, pollenkitt (as occurs in almost all entomophilous species) for later dispersion – the presentation phase; (4) pollen is dispersed by different agents, remaining exposed to the environment for different periods – the dispersal phase; and (5) pollen lands on a stigma and, in the case of a compatible stigma and suitable conditions, undergoes rehydration and starts germination – the pollen–stigma interaction phase.

Scope

This review highlights the issue of pollen water status and indicates the various mechanisms used by pollen grains during their five developmental phases to adjust to changes in water content and maintain internal stability.

Conclusions

Pollen water status is co-ordinated through structural, physiological and molecular mechanisms. The structural components participating in regulation of the pollen water level, during both dehydration and rehydration, include the exine (the outer wall of the pollen grain) and the vacuole. Recent data suggest the involvement of water channels in pollen water transport and the existence of several molecular mechanisms for pollen osmoregulation and to protect cellular components (proteins and membranes) under water stress. It is suggested that pollen grains will use these mechanisms, which have a developmental role, to cope with environmental stress conditions.  相似文献   
4.
衣艳君  刘家尧 《生态学报》2007,27(12):5238-5244
利用快速叶绿素荧光动力学技术研究了毛尖紫萼藓脱水和复水过程中叶绿素荧光变化,结果显示在脱水过程中毛尖紫萼藓PSⅡ的最大光化学效率(Fv/Fm)、光合机构电子传递的量子产额(ETo/ABS)、捕获的激子将电子传递到电子传递链中超过QA的其它电子受体的概率(ETo/TRo)、单位叶面积的反应中心的数量(RC/CSo)以及PSⅡ受体库(Area)对叶片含水量的响应等均存在相对含水量阈值。在阈值范围内脱水,对以上荧光参数影响不大,低于阈值后,各荧光参数值迅速下降,直至PSⅡ反应中心完全关闭以及光化学过程结束。再复水后,毛尖紫萼藓光合机构的最大捕光效率、实际光化学效率、PSⅡ反应中心受体侧的电子传递链以及反应中心均能得到快速而有效的恢复。表明一定时间内脱水不会对毛尖紫萼藓的光合器官造成严重伤害,光合系统仍维持在可恢复状态。  相似文献   
5.
6.
Iron deficiency and diarrhea are two of the most significant issues for global health. Iron deficiency anemia is the most common nutritional deficiency in the world, affecting nearly 25% of the world population (UNICEF/WHO 1999). The prevalence of iron deficiency in developing countries is illustrated by comparison with other deficiencies: iron deficiency affects 3.5 billion people, while vitamin A and iodine deficiency affect 0.3 billion people and 0.8 billion people, respectively. The prevalence is highest among young children and women of childbearing age (particularly pregnant women). It is estimated that national productivity levels could be raised as much as 20% by correcting iron deficiency in developing countries. Recombinant human lactoferrin (rhLF), expressed and extracted from rice seed, is being evaluated by Ventria Bioscience for use as a dietary supplement to treat iron deficiency and/or iron deficiency anemia. Diarrhea is also a major world health issue. Sixty percent of children who die under age five die of pneumonia, diarrhea or measles. World Health Organization oral rehydration solution (WHO-ORS) is one of the major medical advances in the past 50 years, saving the lives of 1 to 2 million children annually. Many studies have demonstrated similar efficacy of rice-based ORS. There are studies documenting the reduced frequency of diarrhea in breast-fed children and this health improvement is attributed to the antimicrobial action of the human milk proteins lactoferrin and lysozyme. In vitro data document the growth inhibition of the diarrheal associated organisms: rotavirus, ETEC, cholera, salmonella, and shigella by human lactoferrin (hLF) and human lysozyme. Using Ventria's ExpressTec system, we have expressed human lactoferrin and human lysozyme in rice. In a rice-based ORS formulation, these proteins have the potential to provide not only the benefits of reduced stool volume and improved weight gain, but also shorten the course of diarrheal episodes via antimicrobial activity against the causative agent.  相似文献   
7.
I n vitro and in vivo rehydration and germination in Cupressus arizonica pollen were examined using light and scanning electron microscopy. Shed pollen has 12.6% water content, which reduced to 8.2% after dispersal, and this latter pollen survived for some months at room temperature and for years at −10 °C. Rehydration requires breaking of the sporoderm walls and depends on the composition and pH of the rehydration medium. Acidity restrains the breakage, while alkalinity promotes it. Pollen division follows exine shedding and requires the persistence of the mucilaginous layer; hence, pH values countering these outcomes prevent division. Division results in a large and a small cell separated by a callosic wall. A pollen tube develops from the innermost intine of the large cell, which is callosic, and extends into the mucilaginous middle intine. The percentage germination never exceeded 17% in all tested media. In vivo , pollen rehydrates and casts off the exine in the micropylar drop. Drop withdrawal brings pollen to the apical nucellar cells that degenerate in the meantime, and it leaves a deposit on the surface of the micropylar canal. After contaction of the nucellar cells, the pollen flattens and its mucilaginous layer shrinks and disappears. This occurs simultaneously with sealing of the micropylar canal. During this time, pollen divides asymmetrically without the callosic wall, and the larger cell develops a tube in the interface with the nucellus. Only some pollen grains accomplish adhesion to the nucellus and germinate. The in vitro and in vivo developmental stages are discussed.  相似文献   
8.
Plant responses to water deficit occur in a complex framework of organ interactions, but few studies focus on the effect of drought stress on all organs in a whole-plant. The effects of repeated dehydration and rehydration (DH) on physiological and biochemical responses in various organs of Periploca sepium Bunge (P. sepium) were investigated. The leaf relative water content decreased significantly during drought, but recovered and showed an increase when compared to well-watered control plants. The malondialdehyde (MDA) content increased in mature and old leaves, but decreased in young leaves, new stems and fine roots during drought, indicating that the young and vigorous tissues of a whole-plant are protected preferentially from the oxidative stress. Among all organs, the fine roots showed the highest levels of proline, total free amino acids (TFAA) and Na+, while the leaves showed the highest levels of total soluble sugars (TSS), soluble proteins (SP), Ca2+ and Mg2+. The response to DH differed in different organs, both in magnitude and in the type of solutes involved. Drought stress increased the contents of proline, TFAA, TSS, SP and K+ in all organs of P. sepium plants, while the accumulation amounts were obviously different among the organs. The storage starch in stems and roots plays an important role in providing carbohydrates for growth. Changes in Na+, Ca2+ and Mg2+ under DH presented a high degree of organ specificity. Our data indicates that response strategies are different between different organs; therefore, evidence the needs to integrate all the information in order to better understand plant tolerance mechanisms.  相似文献   
9.
Immunogold labeling of cryosections according to Tokuyasu (Tokuyasu KT. A technique for ultracyotomy of cell suspensions and tissues. J Cell Biol 1973;57:551–565), is an important and widely used method for immunoelectron microscopy. These sections are cut from material that is chemically fixed at room temperature (room temparature fixation, RTF). Lately in many morphological studies fast freezing followed by cryosubstitution fixation (CSF) is used instead of RTF. We have explored some new methods for applying immunogold labeling on cryosections from high‐pressure frozen cells (HepG2 cells, primary chondrocytes) and tissues (cartilage and exocrine pancreas). As immunolabeling has to be carried out on thawed and stable sections, we explored two ways to achieve this: (1) The section fixation method, as briefly reported before (Liou W et al. Histochem Cell Biol 1996;106:41–58 and Möbius W et al. J Histochem Cytochem 2002;50:43–55.) in which cryosections from freshly frozen cells were stabilized in mixtures of sucrose and methyl cellulose and varying concentrations of glutaraldehyde, formaldehyde and uranyl acetate (UA). Only occasionally does this method reveal section areas with excellent cell preservation and negatively stained membranes like Tokuyasu sections of RTF material. (Liou et al.) (2) The rehydration method, a novel approach, in which CSF with glutaraldehyde and/or osmium tetroxide (OsO4) was followed by rehydration and cryosectioning as in the Tokuyasu method. Especially, the addition of UA and low concentrations of water to the CSF medium favored superb membrane contrast. Immunogold labeling was as efficient as with the Tokuyasu method.  相似文献   
10.
Effects of potassium on the photosynthetic recovery of Nostoc flagelliforme (Berk. & Curtis) Bornet & Flahault were investigated to determine its exact role during rehydration. Potassium enhanced recovery of the ability to reduce the primary quinone‐type acceptor (QA) and plastoquinone (PQ) pool and the area over the fluorescence rise curve was increased by 127%. The proportions of closed PSII reaction centers at phases J and I and the net rate of closure of PSII reaction centers were decreased by, respectively, 19%, 8%, and 23% with the addition of potassium, due to changes in the ability of PSII for multiple turnovers needed to reduce the PQ pool. Potassium significantly enhanced the probability of electron transfer beyond QA and the recovery of electron transport flux per PSII reaction center. Electron transport from water to methyl viologen for samples rehydrated in K+‐free BG11 medium was 54% of those with the addition of potassium. However, electron flow from water to p‐benzoquinone and from reduced 2,6‐dichlorophenol‐indophenol to methyl viologen showed little change with the addition of potassium. The fast phase and slow phase of millisecond delayed light emission and the ATP content for samples rehydrated in K+‐free BG11 medium were, respectively, 71.6%, 50.7%, and 77.1% of those with the addition of potassium. These suggested that potassium affected electron transfer from PQ to plastocyanin through the cytochrome b6f complex and the proton motive force across the thylakoid membranes, probably reflecting its role in charge balance during H+ transport by the cytochrome b6f complex.  相似文献   
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