超临界CO_2流体处理工艺对木材渗透性的影响

以苯—乙醇为夹带剂,研究超临界CO2流体不同处理压力、温度、时间对福建产杉木、马尾松、檫木木材渗透性的影响。结果表明,在35 MPa内,处理压力的增大有利于3种木材渗透性的提高;杉木在处理温度为40℃时,渗透性的变化率达到最大,为493%,马尾松和檫木在处理温度为45℃时,渗透性的变化率达到最大,分别为479%和349%;较佳的处理时间为30 min。     

轮纹病菌侵染对不同抗性苹果品种膜透性及防御酶的影响

对轮纹病菌Botryosphaeria berengriana f.sp.piricola侵染3个不同抗性苹果品种枝条后的细胞膜透性及防御酶系的变化进行了测定,以分析其与抗性的关系。结果表明,接种后38天内,3个品种电解质渗出率均有先升后降的趋势,鸡冠、国光和富士电解质渗出率变化的峰值分别为8.1%、12.2%和18.4%,抗病品种鸡冠的变化明显低于感病品种富士和国光。接种后35天内,苯丙氨酸解氨酶、超氧化物歧化酶、过氧化物酶和多酚氧化酶也表现为先升后降的趋势,且抗病品种的峰值出现较晚。抗病品种鸡冠的苯丙氨酸解氨酶、超氧化物歧化酶和过氧化物酶活性变化峰值分别为234、50.88U·g-1FW·h-1和14.22U·g-1FW·min-1,高于国光和富士,而多酚氧化酶活性变化的峰值为37.78U·g-1FW·min-1,低于感病品种国光和富士。     

人工模拟高温环境下白三叶草相对生理指标测定

研究了高温胁迫条件下白三叶叶片相对含水量、膜透性、脯氨酸含量和叶绿素含量的变化规律。结果表明:25~35℃处理0.5 h后,白三叶的膜透性、脯氨酸含量逐渐上升,相对含水量、叶绿素含量逐渐下降,但幅度不大;45℃以上高温处理后,以上生理指标均有显著性大幅度的变化。与CK比较,温度每升高5℃,白三叶细胞质膜透性、脯氨酸含量平均增加50.62%、59.89%,而相对含水量、叶绿素含量分别下降34.22%、4.61%。在实验条件下,白三叶能适应35℃的高温,40~45℃为其忍耐高温的临界温度范围,50℃为致死温度上限。     

Changes in antioxidative system and membrane damage of lettuce in response to salinity and boron toxicity

Individual and combined effects of salinity and B toxicity on growth, the major antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX) activities, ascorbic acid, proline, and H₂O₂ accumulation, and stomatal resistance (SR), malondialdehyde (MDA), membrane permeability (MP) and the concentrations of sodium (Na), chloride (Cl) and boron (B) of lettuce were investigated. Boron toxicity and salinity reduced growth of lettuce plants. Under B toxicity, B concentration of the plants was increased, but in the presence of NaCl, the concentration of B was significantly reduced. Sodium and Cl concentrations were increased in B + NaCl and NaCl treatments. Membrane damage was more pronounced in NaCl and B + NaCl treatments. Stomatal resistance of the plants was significantly increased by salinity treatments. The accumulation of proline and ascorbic acid was the highest in the B + NaCl treatment. In general, stress conditions significantly increased H₂O₂ and antioxidant enzyme (SOD, CAT and APX) activities. The present results indicate that stomatal closure is an important response of lettuce against NaCl and B + NaCl stress. Furthermore NaCl and B + NaCl toxicity-induced oxidative stress in lettuce resulting in lipid peroxidation and membrane damage. Increased antioxidant enzyme activities and also accumulation of ascorbic acid and proline are involved in order to overcome B- and NaCl-induced oxidative stress.     

The basic mechanism of increased microvascular permeability

The increased microvascular permeability appears mainly in venule during inflammation, shock, and burns. Endothelial cells play an important role in venule permeability enhancement. There are two kinds of pathway for macromolecule extravasation. One is paracellular pathway and another is transcellular pathway, which are related to the formation of endothelial gap or transcellular openings seperately. The alteration of intercellular related protein, such as occludin, claudin, zona occludens (ZO), junctional adhesion molecule (JAM), VE cadherin, catenin, integrin, etc, and the alteration of endothelial cytoskeleton, such as rearrangement of actin filament, formation of stress fiber and focal adhesion, etc, involve in the pathogenesis of increased microvascular permeability.     

Angiopoietin-1 and regulation of vascular permeability

Angiopoietin-1 (Ang-1) is a newly-found endothelium-specific proangiogenic factor and it had been proved essential roles in both vasculogenesis and angiogensis. Among them, its anti-leakage ability may have great potential applications in clinical treatment of vascular hyper-permeability in a variety of diseases such as cancer, diabetic retinopathy, rheumatoid arthritis, asthma. In this review, some research progresses focused on this aspect are discussed.     

Permeability of the endothelium and partitioning of the pulmonary blood flow resistance in isolated perfused pig lungs: Effects of breed and age

The right and left lungs of 5 healthy Minipigs and of 13 healthy Landrace piglets were isolated, perfused at constant pressure and maintained in an isogravimetric state under zone III conditions (pulmonary venous pressure>alveolar pressure). By applying the double, arterial and venous, occlusion technique, the total blood flow resistance (R _t) was partitioned into four components: arterial (R _a), pre-(R _a) and post-capillary (R _v) and venous (R _v). The capillary filtration coefficient (K _f,c) was evaluated by measuring the weight gained by the lungs when the arterial and venous pressures were suddenly increased. In the youngest Landrace piglets (5 weeks old), there was an uncontrolled vasoconstriction which sometimes prevented perfusion of the lungs and induced a large increase inR _t. These high values ofR _t were decreased by tolazoline administration. The values ofR _t recorded in older pigs (12–13 weeks old) were lower in Minipigs (33.66±3.77 cmH₂O min L^–1 per 100 g of lungs;n=5) than in Landrace piglets (55.20±6.18 cmH₂O min L^–1 per 100 g;n=5). This breed difference was due to the differences inR _a andR _v. The mean values ofK _f,c were 0.193±0.015 and 0.202±0.029 ml min (cmH₂O)^–1 per 100 g of the lungs in Minipigs and Landrace piglets respectively. All these parameters were stable for the 3 hours following the equilibrium period. It was concluded that: (1) There is an age-related maturation of the control of the vasomotor tone in porcine lungs. (2) Pulmonary microvascular haemodynamics are influenced by the breed of the pigs. (3) There was no difference in theK _f,c values between both the breeds. (4) A comparison of the values reported for dogs and rabbits with our data shows that the pre- and post-capillary resistances and, to a lesser extent, the arterial and venous resistances are relatively high in pigs.     

Mechanism of exogenous nitric oxide in attenuating endotoxin-induced increase of rat pulmonary microvascular permeability

AIM and METHODS:The animal model of acute lung injury (ALI) caused by intratracheal instillation of lipopolysaccharides(LPS) in vivo and human peripheral blood polymorphonuclear neutrophil (PMN) in vitro were used to study the effects of sodium nitroprusside (SNP), nitric oxide (NO) donor, on LPS-induced PMN accumulation, microvascular permeability and PMN apoptosis. RESULTS:①In vivo, PMN accumulation in lung, the protein content in bronchoalveolar lavage fluid (BALF) and the Evans blue dye and monastral blue dye extravasation in lung tissue of LPS group were markedly higher than those of both sham operation group and LPS+SNP group. ②In vitro, the apoptotic percentage of SNP group was much higher than that of control group, while compared with LPS group, SNP+LPS group has significantly higher apoptotic percentage. CONCLUSIONS:SNP intratracheal instillation attenuated LPS-induced microvascular permeability and alleviated ALI. PMN apoptosis induced by SNP may be one of the potential mechanisms underlying the decrease of PMN accumulation in lung tissue.     

煤矸石组分与表土质地对充填重构土壤导气率的影响

研究煤矸石组分及表土质地对煤矸石重构土壤导气率的影响,探讨重构土壤这种差异显著的非均质土壤导气内在机理,为进一步研究复杂的非均质土壤导气特性提供理论基础。通过在煤矸石中掺杂不同粒径碎石来改变其组分,并利用3种不同质地的土壤在土柱内进行土壤剖面重构,采用一维瞬态法测量其导气率。结果表明:(1)不同碎石粒径和质量分数对混合基质饱和含水量影响不同,掺杂2~5mm粒径碎石,随着质量分数的增加,饱和含水量逐渐增加,从7.29%增加到12.9%;掺杂5~10mm粒径碎石,饱和含水量随着质量分数的增加先增加后减少,分别为7.28%,8.5%,6.9%。(2)煤矸石的导气率远大于土壤,并且煤矸石的导气率对水分的敏感度随质量含水量的增加而增加,而土壤的导气率对水分变化的敏感度均随质量含水量的增加而降低。(3)碎石的存在为大孔隙的产生创造条件的同时也会减少了土壤通气断面,阻隔空气传输的通道。(4)重构土壤导气率受表土质地和底部填充介质的共同影响,覆土土壤导气率决定了重构土壤的导气率大小,而充填基质导气率决定了充填介质对重构土壤导气率影响的系数(Ska)。Ska与充填介质导气率呈显著相关,可以通过指数函数进行拟合(R2=0.93)。通过充填介质及覆土土壤的导气率可以对重构土壤导气率进行估算,简化了重构土壤导气率的测定过程。     

苯甲酸、肉桂酸对西瓜根细胞保护酶及膜透性的影响

自毒作用是导致西瓜连作障碍的重要因素之一,利用已知的西瓜主要自毒物质苯甲酸和肉桂酸,研究其对西瓜根细胞保护酶及膜透性的影响。试验结果表明：苯甲酸、肉桂酸处理可抑制过氧化物酶（POD）活性;对超氧化物歧化酶（SOD）活性表现出促进和抑制双重作用,即低浓度处理可提高酶活性,而高浓度处理则酶活性下降;对于硝酸还原酶（NR）,只有肉桂酸表现出促进和抑制双重作用,而苯甲酸对NR活性则只表现出抑制作用;苯甲酸、肉桂酸对根细胞质膜H＋-ATPase活性的影响比较复杂,在低浓度下（〈0.250 mmol/L）先下降,而后有上升趋势（0.250~0.500 mmol/L）,进而随处理浓度（〉0.500 mmol/L）的增加又下降。对于POD、SOD、NR酶活性的影响,苯甲酸的作用强度大于肉桂酸,而对根细胞质膜H＋-ATPase活性的影响,则是肉桂酸大于苯甲酸。苯甲酸、肉桂酸处理可增加根细胞膜透性,且苯甲酸的作用大于肉桂酸。