紫外激光消融主动脉斑块和感生荧光光谱观测

利用XeCI准分子激光辐照主动脉血管正常组织和斑块组织,观察到组织被激光消融。消融所产生的凹坑与辐射时间呈对数直线关系。308nm激光感生的血管壁荧光光谱在可见波段出现二个荧光极大值,用二极值的相对强度之比可以判断正常或斑块组织。     

垂体后叶素和加压素对离体心肌的直接作用

本实验采用大鼠离体右心房和右心室肌条模型,观察了垂体后叶素和加压素对右心房和右心室肌的直接作用。结果表明:垂体后叶素对右心房的自主性收缩频率和幅度及右心室肌的收缩幅度均有剂量依赖性抑制作用;加压素对右心房和右心室肌收缩幅度也有剂量依赖性抑制作用,但对右心房自主节律无影响;催产素对右心房的收缩频率和幅度则均无影响。加压素V_1、V_2受体拮抗剂d(CH_2)_5Tyr(Me)AVP和d(CH_2)_5(D-Ile~2,Ile~4,Ala(NH_2)~9)AVP对垂体后叶素的负性变力作用具有不同程度的阻断作用,但对垂体后叶素的负性变时作用无阻断作用。以上结果提示,垂体后叶素的负性变力作用主要是由加压素产生的,加压素对心肌有直接的负性变力作用;垂体后叶素的负性变时作用可能是非加压素和催产素成分的作用结果。     

Further investigation on nuclear transplantation in different orders of teleost: the combination of the nucleus of Tilapia (Oreochromis nilotica) and the cytoplasm of Loach (Paramisgurnus dabryanus).

The nucleus of a blastula cell from Tilapia (Oreochromis nilotica, family Cichlidae, order Perciformes) was transplanted into an enucleated egg of Loach (Paramisgurnus dabryanus, family Cobitidae, order Cypriniformes). From among 3747 nucleo-cytoplasmic hybrid (NCH) eggs two NCH larval fish (0.05%) were obtained; one died on the 6th day and the other died on the 12th day after the operation. Morphological examinations showed that both NCH larval fish had developed normally with an opened mouth except they could not take food after complete utilization of their egg yolk on the 5th day of development. The possible mechanisms for obtaining such inter-order NCH larval fish are discussed. This is the first report indicating that inter-order NCH larval fish can be obtained in spite of their evolutionary divergence.     

A method for studies of an El Tor-associated antigen of Vibrio cholerae O1

A method for studying the biotype El Tor associated mannose-sensitive haemagglutinin (MSHA) of V. cholerae O1 has been developed. By using crude MSHA adsorbed to chicken erythrocytes as solid phase antigen in an enzyme-linked immunosorbent assay (ELISA), antisera against V. cholerae of the El Tor biotype reacted in high titre with the MSHA-coated cells, whereas antisera against vibrios of the classical biotype did not bind significantly, i.e. in higher titre than pre-immune sera. The binding of anti-MSHA serum, or a monoclonal antibody against MSHA, to the MSHA-coated erythrocytes could be efficiently inhibited by crude MSHA as well as by El Tor vibrios whereas neither V. cholerae lipopolysaccharide nor different strains of classical vibrios had any inhibitory effect. These results support the existence of an El Tor-associated immunogen. They also suggest a possibility of determining antibodies against different haemagglutinins in ELISA without having access to purified antigens.     

The effect of papulacandin B on (1----3)-beta-D-glucan synthetases. A possible relationship between inhibition and enzyme conformation

The antibiotic, papulacandin B, inhibited growth or (1----3)-beta-D-glucan synthetase (or both) in the fungi Saccharomyces cerevisiae, Hansenula anomala, Neurospora crassa, Cryptococcus laurentii, Schizophyllum commune and Wangiella dermatitidis. No effect was observed on Achlya ambisexualis. There was no apparent correlation between the inhibition of growth and that of the synthetase. With most of the fungal extracts, the inhibition of glucan synthetase by papulacandin B became less pronounced as the substrate (UDP-glucose) concentration was decreased. At very low levels of UDP-glucose, with the enzymes from S. cerevisiae and W. dermatitidis, the antibiotic stimulated the activity of glucan synthetase. As further studied with the W. dermatitidis enzyme, those low concentrations of UDP-glucose corresponded to a sigmoidal portion of the rate vs. substrate curve. The sigmoid segment of the curve extended to higher concentrations of UDP-glucose as the temperature was increased. Concomitantly, the range of substrate concentrations at which papulacandin B stimulated the reaction or was noninhibitory was broadened. It is tentatively concluded that glucan synthetase may exist in more than one interconvertible form. The stimulatory effect of papulacandin B is possibly due to preferential binding to the active form of the enzyme. The equilibrium between these forms could be shifted by structural changes in the membrane in which the enzyme is embedded. The lack of correlation between the effects of papulacandin B in whole cells and in extracts is discussed in terms of the variations in membrane structure in the two situations.     

Potent and selective anti-HTLV-III/LAV activity of 2',3'-dideoxycytidinene, the 2',3'-unsaturated derivative of 2',3'-dideoxycytidine

2',3'-Dideoxycytidinene (ddeCyd), the 2',3'-unsaturated derivative of 2',3'-dideoxycytidine (ddCyd) is, like ddCyd itself, a potent and selective inhibitor of HTLV-III/LAV in vitro. This conclusion is based on the relatively high ratio of effective antiviral dose (0.3 microM) versus cell growth inhibitory concentration (20-35 microM) and the lack of any appreciable inhibitory activity against a series of non-oncogenic RNA and DNA viruses. Both compounds were considerably more inhibitory to human lymphoid cell lines than human nonlymphoid or murine cell lines. They were highly dependent on prior activation by deoxycytidine kinase to exert their anti-HTLV-III/LAV and cytostatic effects. In contrast with ddCyd, ddeCyd lost part of its anti-retrovirus effect upon prolonged incubation (10 days) with the virus-infected cells in culture.     

Thermodynamic parameters are sequence-dependent for the supercoil-induced B to Z transition in recombinant plasmids

The entropy and enthalpy changes which contribute to the thermodynamics of the B to Z transition were determined for three recombinant plasmids containing a (dC-dG)16 tract and for a plasmid containing a pair of (dT-dG)20 regions. For each base pair which adopts a left-handed conformation in the plasmids with (dC-dG)16 sequences, the delta HBZ and delta SBZ are -2.1 kcal/mol bp and -8.8 cal/K-mol bp, respectively. In the plasmid containing the (dT-dG)20 tracts, however, the delta HBZ and delta SBZ values are 0.58 kcal/mol bp and -0.76 cal/K-mol bp, respectively. Also, these determinations show that for each B-Z junction that forms in the plasmids containing the (dC-dG), the enthalpy and entropy changes are 24 kcal/mol junction and 65 cal/K-mol junction, whereas for the (dT-dG) plasmid, the enthalpy and entropy changes are -1.8 kcal/mol junction and -22 cal/K-mol junction, respectively. Those values for the enthalpy and entropy changes for the formation of a BZ junction in (dC-dG) and (dT-dG) plasmids suggest that the properties and possibly the structures of the junctions are different. Calculations using the enthalpy and entropy changes determined in this study reveal that the B to Z transition in plasmids containing (dC-dG) blocks are more temperature-dependent than the transitions in plasmids with (dT-dG) blocks. Surprisingly, at temperatures above 60 degrees C, calculations indicate that the B to Z transitions in (dT-dG) plasmids should be energetically favored over that transition in (dC-dG) plasmids.     

Increased 5-Hydroxytryptamine and Norepinephrine Release from Rat Brain Slices by the Red Sea Flatfish

The effect of the Red Sea flatfish toxin pardaxin was examined on K+-evoked and on basal release of either [3H]norepinephrine or [3H]5-hydroxytryptamine from preloaded rat cortical slices. The K+-induced release of the neurotransmitters was stimulated in a dose-related manner at concentrations ranging from 0.5 to 4 micrograms/ml. Basal release of the two transmitters was elevated to a lesser extent. Although the stimulation of evoked release was approximately equivalent for the two neurotransmitters, the response to 5-hydroxytryptamine was reversible whereas that of norepinephrine was not washed by 20 min of superfusion. The mechanisms involved in producing these actions of pardaxin are not known; however, they may be mediated by changes in electrolyte fluxes across the neuronal membranes.     

伸展素在黄瓜胞壁中的转化及其与羟脯氨酸和异联酪氨酸的关系

用~(14)C-Pro和~3H_2-Tyr离体暗培养黄瓜子叶,发现细胞质、SECW和RCW中的Hyp/Pro和Idt/Tyr都随时间呈线性增加。这两种比值后两者高于前者,而两种比值增加速度之比在胞质部分最大、RCW中最小。表明在胞质和胞壁中都有Pro羟化和Tyr异联化过程,但羟化作用主要发生在胞质中,异联化主要在RCW中。 理化处理(高渗溶液和CHM)和放射性示踪证明胞质中存在HRGP库;它被分泌到胞壁后,先以离子键与壁结合,后转变为共价键与壁结合的伸展素。