壳聚糖醋酸溶液对凝血作用的研究

研究了不同脱乙酰度和不同分子量壳聚糖醋酸溶液的凝血作用。发现壳聚糖醋酸溶液使抗凝血液中红细胞发生了明显的聚集和变形。通过不同分子量和脱乙酰度壳聚糖的促红细胞聚集实验,证明了低脱乙酰度壳聚糖(60%~70%)使红细胞聚集效果更好,分子量在105~106范围内作用不十分明显。对血液的凝血酶时间(TT)、凝血酶原时间(PT)、活化部分促凝血酶原激酶时间(APTT)和纤维蛋白原浓度(FIB)的测定结果验证了壳聚糖醋酸溶液凝血机理不依赖于血小板和常规“瀑布”凝血机制。     

A monoclonal antibody (RH1-38) which inhibits multiple systems of cell-mediated cytotoxicity--II. Evidence that the epitope recognized is involved in a late step in the cytolytic mechanism

A monoclonal antibody (RH1-38) which blocks multiple systems of cell-mediated cytotoxicity was functionally characterized. RH1-38 specifically blocks, in the absence of complement, natural killer (NK) activity (K562 targets) without any effect on NK-K562 conjugate formation. Kinetic studies suggested that the antibody blocks a step that occurs 30-120 min after effector populations are mixed with target cells. Single-cell cytotoxicity assays in agarose, combined with standard 51Cr release assays and Michaelis-Menten analysis revealed that RH1-38 markedly decreases Vmax and the number of active NK cells, again without any effect on the number of target-binding cells. The maximum recycling capacity was usually decreased, but in some experiments unchanged, in the presence of the monoclonal antibody. RH1-38 inhibited equally well whole peripheral blood mononuclear leukocytes (PBML), Percoll-fractionated lymphocytes enriched for NK activity, and interferon (IFN)-boosted NK activity. PBML exposed to RH1-38 and then washed mediated depressed NK activity which was partially reversed by subsequent treatment with IFN. These studies are most consistent with the hypothesis that RH1-38 inhibits a step late in the NK cytolytic mechanism rather than through an effect on conjugate formation. The primary effect is probably not on the IFN-generating or boosting mechanism, but a secondary effect on IFN-related mechanisms cannot be ruled out. Inhibition through an effect on a small lymphocyte modulator of NK activity is also unlikely but not rigorously excluded. Thus, RH1-38 appears to inhibit NK activity through a direct effect on NK effector cells, probably by interfering with a cell-surface molecule which is important in the expression of NK activity. The companion paper demonstrates that this monoclonal antibody immunoprecipitates a molecule which is very similar or identical to the LFA-1 antigen. Thus, RH1-38 recognizes either a novel epitope on the LFA-1 molecule or alternatively a distinct, functional killer cell surface molecule. The epitope appears to be involved in a late step in the cytolytic mechanism, possibly part of the effector cell lytic machinery.     

Reversibility of Effects of Very Hypotonic Fluids on in Vitro Frog Gastric Mucosa: A Functional and Morphological Study

Functional and morphological properties of the in vitro frog gastric mucosa were studied during and after exposure to very hypotonic (? 25 mOsM) solutions. Within 20 min the acid secretory rate decreased to zero, but it returned to normal levels after isotonic fluids had been restored. The potential difference (PD) dropped within the first minutes after the exposure to hypotonic solutions, and became inverted. Following the return of isotonic conditions the PD increased to levels higher than in the controls. The electrical resistance increased about 10–fold during the hypotonic period, but decreased to near normal values when isotonic conditions were restored. By light and electron microscopy the cells of the hypotonic mucosae appeared greatly swollen, and the alterations were assessed by morphometric methods. The gland lumina were almost obliterated, and the lamina propria was reduced to about 60% of its former volume. After the return to isotonic conditions normal morphology was restored. It is conceivable that the great increase in resistance during the hypotonic period was caused by the occlusion of the gland lumina. Quantitative analyses of the Na, K, and C1 tissue concentrations indicated a large loss of these ions during the hypotonic state. Presumably the epithelial cells in the hypotonic mucosae avoid bursting by rapidly letting large numbers of ions exit, which results in a cellular osmolarity close to that of the bathing fluids.     

不同保存液对离体大鼠心脏保存效果的研究

目的:研究在冷缺血期3种液体对鼠心脏保存的效果。方法:将24只大鼠随机分为3组,每组8只。3组离体鼠心脏分别用Histidine-tryptophan-ketoglurate(HTK)液,UniversityofWisconsin(UW)液及St.ThomasⅡ(ST)液灌注停跳,并4℃冷冻保存6h。利用离体鼠心非循环式Langendorff灌流功能测定模型,测定左心室舒张期末压(LVEDP)、左心室发展压(LVDP)、左心室压力变化率(dp/dt_max,dp/dtmin)、冠脉流出量(CF),留取冠脉流出液检测心肌酶漏出量,并检测心肌线粒体三磷酸腺苷(ATP),取心肌标本测干湿比。结果:HTK组保存的心肌左心室功能恢复明显优于UW组(P＜0.05),UW组明显优于ST组(P＜0.05),LVEDP恢复HTK组和ST组无显著差异(P＞0.05),但均较UW组恢复好(P＜0.05)。保存后心肌ATP测定值HTK组高于UW组(P＜0.05),UW组高于ST组(P＜0.05)。3组心肌标本测干湿比结果无显著差异(P＞0.05)。结论:HTK液保存心肌效果最好,含有高钾的保存液对冠脉有损害。     

The thymus as primary site for antigen-specific T suppressor cells in neonatally induced tolerance to bovine serum albumin

The ontogeny of antigen-specific T suppressor cells in thymus and spleen was analyzed in CBA/Ca mice which were rendered tolerant as neonates by subimmunogenic doses of bovine serum albumin (low-zone tolerance). Activity of T suppressor cells from those mice was assessed by an assay in which spleen cells from animals primed with fluorescein-conjugated human gamma globulin can be stimulated in vitro to produce IgG anti-fluorescein antibodies when cultured in the presence of fluorescein-conjugated bovine serum albumin. Carrier-specific T suppressor cells appear first in the thymus (day 10), and much later (day 30) in the spleen. The data are discussed in connection with the possible role of T suppressor cells during induction of tolerance in newborn mice.     

Hypothermic Machine Preservation in Liver Transplantation Revisited: Concepts and Criteria in the New Millennium

To overcome the present shortage of liver donors by expansion of the existing donor pool and possibly lengthening of the storage time, hypothermic machine perfusion of the liver as a dynamic preservation method is revisited. The three most important aspects are defined to be the type of preservation solution, the characteristics of perfusion dynamics, and the oxygen supply. Reviewing hypothermic liver machine perfusion experiments, the University of Wisconsin machine preservation solution is the solution most used. It is also found that nothing conclusive can be said about the optimal perfusion characteristics, since either perfusion pressure or perfusion flow is reported. The best estimation is perfusion of the liver in a physiological manner, i.e. pulsatile arterial perfusion and continuous portal venous perfusion. The applied pressures could be chosen to be somewhat lower than physiological pressures to prevent possible endothelial cell damage. Oxygen supply is necessary to achieve optimal preservation of the liver. The minimal amount of partial oxygen pressure required is inversely related to the normalized flow. Incorporating these features in a system based on existing standard surgical and organ sharing procedures and which is able to work stand-alone for 24 h, weighing less than 23 kg, could successfully implement this technique into every day clinical practise.     

Activity of human erythrocyte gangliosides as a receptor to HVJ

Liposomes could bind and fuse efficiently to human erythrocytes in the presence of HVJ when they contained gangliosides isolated from human erythrocytes. Sialosylparagloboside, which has a terminal sequence of NeuAcα2?3Ga1β1?4GlcNac, has a much higher receptor activity to the virus than GD_1a, GD_1b, GT_1b, and GT_1a, all of which contain the terminal sequence of NeuAcα2?3Galβ1?3GalNAc or NeuAcα2?8NeuAcα2?3Galβ1?3GalNAc. The activity of sialosylparagloboside is comparable to that of glycophorin, a major sialoglycoprotein of human erythrocytes, when compared on the basis of the required amount (as sialic acid) of compounds. The high affinity of sialosylparagloboside to the viral HANA protein is also suggested by the finding that it showed high inhibitory activity against HVJ-mediated binding of glycophorin liposomes to erythrocytes. Sialosylparagloboside was also highly susceptible to the viral sialidase, the other biological function of HANA protein.     

Block Copolymers of Methyl Vinyl Ether and Isobutyl Vinyl Ether With Thermo‐Adjustable Amphiphilic Properties

The thermo‐adjustable hydrophilic/hydrophobic properties of AB, ABA and BAB block copolymers in which A is poly(methyl vinyl ether) (PMVE) and B is poly(isobutyl vinyl ether) (PIBVE) have been investigated. The block copolymers were prepared by “living” cationic polymerization using sequential addition of monomers. The polymerizations were carried out with the system acetal/trimethylsilyl iodide as initiator and ZnI₂ as activator. The initiating system based on diethoxyethane leads to AB block copolymers whereas the initiating system based on tetramethoxypropane leads to ABA or BAB triblock copolymers. Well‐defined block copolymers of different composition with controlled molecular weights up to approx. 10 000 have been prepared. When IBVE is added to living PMVE, PIBVE‐blocks form only in the presence of an additional amount of ZnI₂, which is attributed to the fact that part of the ZnI₂ is inactive because of complex formation with PMVE. At room temperature, the combination of hydrophilic (PMVE) and hydrophobic (PIBVE) segments provides the copolymers with surfactant properties. Above the lower critical solution temperature (LCST) of PMVE, situated around 36 °C, the PMVE‐blocks become hydrophobic and the amphiphilic nature of the block copolymers is lost. The corresponding changes in hydrophilic/hydrophobic balance have been evaluated by investigation of the emulsifying properties of the block copolymers for water/decane mixtures as a function of the temperature. Below the LCST, the block copolymers have emulsifying properties similar to or better than those of the commercial PEO‐PPO block copolymers (Pluronic®). Either oil‐in‐water or water‐in‐oil emulsions can be obtained, depending on the polymer architecture and the water/decane volume ratio. The emulsifying properties are strongly reduced or completely lost above 40 °C. Emulsions obtained with a PMVE₃₆‐b‐PIBVE₅₄ block copolymer for a water/decane (v/v) ratio of 85/15 remained stable for more than six months.

50/50 and a 85/15 water/decane w/o emulsion (15 g/l) with the PMVE₃₆‐b‐PIBVE₅₄ block copolymer at 20 °C.     

Changes of lymphoproliferative responses of T cell subsets to allergen and mitogen after hyposensitization in asthmatic children

The cellular basis for the mechanism of hyposensitization was studied by examining the changes in the numbers and proliferative responses to house dust and phytohemagglutinin (PHA) of T cell subsets of 25 house dust-sensitive asthmatic children before and 1 yr after hyposensitization. The results demonstrated (1) No difference was observed in the mean percentages of OKT3+ cells and OKT8+ cells between normal subjects and patients both before and after hyposensitization, but the absolute numbers of both types of cells in untreated patients were much higher than in the normal subjects or treated patients because of relative lymphocytosis in the untreated patients, (2) While the mean percentage of OKT4+ cells of the untreated patients was lower than that of the normal subjects (40.8 +/- 4.7% vs 44.8 +/- 4.5%, p less than 0.007), the absolute number was higher in the former than that in the latter because of the same reason. After hyposensitization, the mean percentage of the OKT4+ cells was slightly increased, and (3) Hyposensitization was able to restore the proliferative capability to PHA and depress the sensitivity to specific allergen of OKT4+ cells on the one hand and augment the proliferative responses to both PHA and allergen of OKT8+ cells on the other. Taken together, these immunologic changes may explain partly the suppressed IgE-antibody production and decreased lymphoproliferative response to specific allergen after hyposensitization.     

三个价型六种盐对C8-卵磷脂胶团溶液液相分离影响的研究

本文研究三个价型六种盐对C_8-卵磷脂微团溶液的液-液相分离调控的规律,测定出各种加盐溶液的两相共存曲线,获得了各系统相变临界温度T_c随盐类型和盐离子强度变化的关系。用我们先前导出的关于盐对该微团溶液相变影响关系的方程式为T_c=T~0_c-A_1[I]~1.2+A_2[I]对本实验结果的拟合表明,这六种加盐微团溶液的液-液相分离亦遵从同样的变化规律。从而为揭示各种价型无机盐对两性离子化表面活性物质微团溶液液相分离的作用规律和机制提供了进一步的实验与理论依据。