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91.
曹威  周仲福 《生理学报》1989,41(4):388-394
We have reported that intracerebroventricular (i. c. v.) injection of 1-4 ng of CCK-8 to the rat produced a remarkable antagonistic effect on morphine analgesia. In order to study the species specificity and the site of action, CCK-8 was microinjected into the PAG of the rabbit, and its influence on morphine analgesia and electroacupuncture analgesia was observed. The latency of the escape response (ERL) to radiant heat focused on the snout was measured as an index of the pain threshold. Microinjections were made via cannulae chronically implanted into the PAG. The drug solutions were delivered in a volume of 1 microliter, at a speed of 0.125 microliter/min. The ERL was measured for a period of 60 or 70 minutes at 10 min intervals. 1. CCK-8 administered unilaterally to the PAG of the rabbit at a dose of 3 ng antagonized the analgesia induced by morphine (4 mg/kg, i. v.) by 73% (P less than 0.001), and reduced the analgesic effect of electroacupuncture by 67% (P less than 0.001). These effects were dose-dependent within the range from 1.5 ng to 6.0 ng. The effect of CCK-8 was reversed by CCK receptor blocker proglumide (4 microliters, intra-PAG injection). Unsulfated CCK-8 (CCK-us) had no effect in this regard. These results indicate that in the PAG of the rabbit, exogenously administered CCK-8 was capable of antagonizing opioid analgesia by the activation of CCK receptors. 2. Two groups of rabbits were given with morphine (2 mg/kg, i. v.) and simultaneous injection of CCK-8 antiserum (CCK-AS, 1 microliter) or normal rabbit serum (NRS) into the PAG.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
92.
In a spheroplasting method which allows the fractionation and quantification of cloned invertase activity in recombinantSaccharomyces cerevisiae cells, the yeast cell is selectively degraded with the enzyme Zymolyase for 60 minutes at 45°C to separate periplasmic proteins from cytoplasmic proteins. Most of the glucose-6-phosphate dehydrogenase (a cytoplasmic marker protein) was found in the cytoplasmic fraction.  相似文献   
93.
Cardiac and vascular actions of sarafotoxin S6b and endothelin-1   总被引:3,自引:0,他引:3  
Snake venom-derived sarafotoxin S6B (SRT) and porcine endothelium-derived endothelin-1 (ET) have striking structural similarities. In conscious, freely-moving rats, ET (0.67 nmol/kg) produced a transient tachycardia and fall in arterial blood pressure which was followed by a long-lasting increase in arterial pressure, bradycardia, decrease in cardiac output (CO) and marked increase in total peripheral resistance. In contrast, SRT (0.67 nmol/kg) produced only the sustained cardiovascular responses. The sustained cardiovascular effects of SRT or ET were similarly attenuated by nifedipine. SRT and ET (30 nM) produced vasoconstriction in the isolated perfused mesenteric vascular bed without initial vasodilation. SRT and ET had potent positive inotropic and negative chronotropic effects on isolated perfused hearts and induced toxic reactions including coronary vasospasm, arrhythmias, A-V block and ventricular fibrillation. In addition to SRT lacking the initial depressor response in vivo, several differences in the activities of the peptides were also observed. ET produced greater and longer-lasting actions than SRT in producing pressor and vasoconstrictor responses in all 3 preparations, and in its ability to induce toxic effects on the heart.  相似文献   
94.
Summary Mesophyl protoplasts of two genotypes of cultivated tomato (Lycopersicon esculentum Mill.) and one of its wild relative species (Lycopersicon peruvianum Mill.) were fused by using electrofusion and polyethyleneglycol-induced fusion. Forty-three fertile tetraploid somatic hybrid plants, each deriving from separate calli, were recovered from both fusion procedures. Electrofusion appeared more efficient than chemical fusion for the production of somatic hybrids. These plants appeared morphologically similar, whatever the fusion procedure and tomato genotype. They had intermediate leaf, inflorescence, and flower morphology. After self-pollination, the hybrids set fruit of intermediate size and color. The hybrid nature of these plants was confirmed by isoelectric focusing of the Rubisco small subunits used as nuclear markers. L. esculentum and L. peruvianum were distinguished by means of two chloroplast markers: CF1-ATPase subunit as analyzed by isoelectro-focusing and ct DNA restriction patterns. All hybrids displayed both ct markers of only one parent with no biased transmission. Mitochondrial (mt) DNAs were prepared from flower buds by using miniaturized CsCl gradients. Preliminary analysis indicated that mt genomes from the hybrids all differed from those of both parents. mt DNA Sall restriction enzyme analysis revealed that all but two hybrids contained one novel fragment of 13.5 kb. Gene mapping experiments showed that the mt apocytochrome b and ATPase subunit 9 homologies in the somatic hybrid mt DNA resembled L. esculentum and L. peruvianum, respectively; the mt nad5 probe distinguished at least four distinct patterns in the hybrids. These results indicated that mt DNA rearrangements involving intergenomic recombinations occurred through protoplast fusion. A greater mt DNA polymorphism was induced with chemical fusion than with electrofusion.  相似文献   
95.
M Han  P W Sternberg 《Cell》1990,63(5):921-931
Genetic analysis previously suggested that the let-60 gene controls the switch between vulval and hypodermal cell fates during C. elegans vulval induction. We have cloned the let-60 gene, and shown that it encodes a gene product identical in 84% of its first 164 amino acids to ras gene products from other vertebrate and invertebrate species. This conservation suggests that the let-60 product contains all the biochemical functions of ras proteins. Extrachromosomal arrays of let-60 ras DNA cause cell-type misspecification (extra vulval fates) phenotypically opposite to that caused by let-60 ras loss-of-function mutations (no vulval fates), and suppress the vulvaless phenotype of mutations in two other genes necessary for vulval induction. Thus, the level and pattern of let-60 ras expression may be under strict regulation; increase in let-60 ras activity bypasses or reduces the need for upstream genes in the vulval induction pathway.  相似文献   
96.
We performed a systematic functional analysis of the human gamma-globin promoter to identify its activator domains. We used a panel of truncation and scanning mutants as well as transfection in human K562 fetal erythroid cells. The various mutations produced relatively small changes in promoter function in both transient and stable transfection assays. The CACCC region and the region containing the binding sites for protein GATA-1 behaved as activator domains. We also obtained evidence for a minor activator site in the - 200 to - 190 region. The results are consistent with the interpretation that gamma-globin gene regulation may occur in part through multiple small effects of promoter elements.  相似文献   
97.
The common denominator of a unique disseminated multi-focal milliary myocardial hyaline necrosis and fibrosis in Keshan disease (KSD) and cystic fibrosis (CF) and a commonality of the affected age groups of fetuses and preschool children led to the review of existing KSD autopsy material to search for pancreatic and hepatic lesions considered pathognomonic for CF. Pancreatic lesions considered pathognomonic for CF were found in 595, or 35% of 1700 documented cases of KSD. The pancreatic lesions were limited to tissues of fetuses and preschool children. Adults dying of KSD had diagnostic lesions limited to the cardiovascular system, liver, and skeletal muscle. Varying degrees of focal biliary cirrhosis were identified in 850, or 50% of the KSD autopsies, and 85, or 5% developed severe lobular cirrhosis. The common denominator in CF and KSD appears to be a primary or induced secondary selenium deficiency in age-susceptable humans, prenatally at or around 22 wk of fetal life, during early postnatal life, or during the rapid-growth preschool years. The basic difference between the natural history of CF and KSD is that the selenium deficiency is totally environmental in KSD and appears to be the result of a maternal malabsorptive syndrome or an abnormality of selenium transfer in CF.  相似文献   
98.
Variability of entrainment of cohesive sediments in freshwater   总被引:6,自引:0,他引:6  
Estimates of sediment entrainment are required for models of particle transport in lakes and estuaries but are difficult to make because of the multiplicity of factors affecting cohesiveness of surficial sediments. We present results of sediment resuspension studies performed in an annular flume calibrated with laser-Doppler velocimetry. In our experiments, using sediments collected from two sites in the R. Raisin which flows into L. Erie and from one site in the western basin of L. Erie near the mouth of the R. Raisin, we applied shear stresses at the sediment-water interface in steps from 2 to 12 dyne/cm2. Percent water content at the surface of the sediments was either 77 or 74%, and trials were run with and without oxygenating the water overlying the sediments. Entrainment rates as a function of shear stress at the sediment-water interface were best described by a power-law relationship. All but 14% of the variability in the power law expression was due to shear stress and percent water content; the variability not accounted for was due to differences in particle size distributions, chemical properties, and biological activity in the sediments.  相似文献   
99.
GABA神经元在金黄地鼠视觉中枢的分布   总被引:3,自引:1,他引:2  
本文用免疫细胞化学技术研究了GABA在金黄地鼠视觉中枢的分布特征,同时用统计学方法作了定量分析,结果表明:GABA阳性神经元分布在整个视皮层和上丘中,呈不均匀分布,外膝体中GABA阳性神经元密度较低.视皮层中GABA阳性神经元密度为781mm~2,占视皮层细胞总数的19.7%,上丘中其密度为812/mm~2,占22.3%,视皮层Ⅰ层中GABA阳性神经元为52%,上丘表层(浅灰层及视觉层GABA阳性神经元为56%,GABA阳性神经元包括不同类型的细胞.在视皮层中可观察到GABA免疫疫应阳性的锥体细胞.  相似文献   
100.
L7811鼠腹水肿瘤细胞^31P核磁共振的研究   总被引:1,自引:0,他引:1  
用~(31)P核磁共振技术(~(31)P-NMR)研究了L_(7811)鼠腹水肿瘤细胞和615系鼠胸腺细胞(正常对照细胞)。结果发现在肿瘤晚期阶段,L_(7811)腹水肿瘤细胞的含磷化合物未进入完全不活跃状态。此外,腹水肿瘤细胞的磷脂组成与含量亦有明显改变。因此,~(31)P-NMR谱可做为观察肿瘤细胞内能量生成和某些磷脂合成宏观动态过程的一项参考指标。  相似文献   
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