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811.
O K Kutitova G Iu Lipskaia S V Maslova V I Agol 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1989,(11):14-20
Oligonucleotide maps of some poliovirus type 2 strains isolated from polio cases, while being clearly related to that of the Sabin vaccine type 2 strain, exhibited, nevertheless, marked differences from the reference (vaccine) map. Several large oligonucleotides derived from 4 such strains were subjected to enzymatic sequencing. The results strongly suggest that all of them were intertypic recombinants between the Sabin strains. The 5'-parts of the genomes of these strains were derived from the type 2 vaccine whereas the 3'-parts were of type 1 (in 2 strains) or type 3 (in other 2 strains) origin. 相似文献
812.
O Pálmai 《Acta physiologica Hungarica》1989,73(2-3):379-381
The emergence of the artificial intelligence (AI) in computer technology and its application in the medical field enables the researchers to carry out such intelligent activities like image processing, medical reasoning systems, clinical decision supporting and natural language understanding, etc. A gastroenterological expert system application is briefly demonstrated in this paper. Similar expert systems can be seen to be useful in the research of gastrointestinal cytoprotection, including the plan of different compounds with cytoprotective effect, experimental and clinical medical research. 相似文献
813.
V B Zbarski? O A Galatenko L P Terekhova O L Ol'khovatova N D Malkina 《Antibiotiki i khimioterapii͡a》1989,34(12):883-885
Novel antibiotics with in vitro activity against gram-positive bacteria were isolated from Actinomadura fulvescens INA 3321 and INA 3852. Conditions for biosynthesis and isolation of antibiotics 3321 and 3852, as well as their physicochemical and biological properties were studied. Chromatographic analysis of the antibiotics revealed that each of them contained two biologically active components. The components were separated with preparative chromatography. Physicochemical properties of the components showed that antibiotics 3321 and 3852 were similar. UV and IR spectroscopy suggested that antibiotics 3321 and 3852 were original compounds not described earlier. 相似文献
814.
O Perche M C Lainé J F Pageaux C Laugier D Sandoz 《Biology of the cell / under the auspices of the European Cell Biology Organization》1989,67(2):123-134
Quail oviduct development is controlled by sex steroid hormones. Estrogen (E) induce cell proliferation, formation of tubular glands by epithelial cell evagination and cell differentiation. Progesterone (P) strongly increases the secretory process in E-treated quails, but inhibits cell proliferation, cell evagination and differentiation of ciliated cells. The balance between E and P is critical for harmonious development of the oviduct. After 6 daily injections of two doses of estradiol benzoate (10 or 20 micrograms/d) and high doses of P (4 mg/d), tubular gland formation by epithelial cell evagination was inhibited, while epithelial cell proliferation occurred, as shown by the height of the villi and the increase in DNA. Secretory processes were strongly stimulated. Ovalbumin, a tubular gland cell marker and avidin, a mucous cell marker, were localized by immunofluorescence and immunogold labeling. Ovalbumin was localized only in the rudimentary tubular glands, whereas avidin was dispersed throughout the secretory cells. High doses of progesterone inhibited tubular gland cell proliferation, disturbed the distribution of avidin and inhibited differentiation of ciliated cells. Ovalbumin synthesis occurred only in epithelial cells which were evaginated despite the hyperstimulation. Ovalbumin gene expression appeared highly dependent upon the cell position. 相似文献
815.
Class II MHC molecules and the HIV gp 120 envelope protein interact with functionally distinct regions of the CD4 molecule. 总被引:9,自引:1,他引:8
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A murine T cell hybridoma with a receptor specific for the class I molecule H-2 Dd was transfected with an expressible cDNA for human CD4. Expression of the human class II MHC molecule HLA-DP on Dd-positive murine fibroblasts resulted in a greatly enhanced response of the CD4-positive T cell hybridoma, measured either by lymphokine production or by rosette formation. Inhibition of these functional assays with anti-CD4 monoclonal antibodies implicated the two amino-terminal domains of CD4 in an interaction with the HLA-DP molecule. This interaction was blocked by incubation with recombinant gp120 envelope protein of HIV. In contrast, recombinant soluble CD4 did not inhibit and was able to prevent the inhibition by gp120. Anti-CD4 antibody blocking experiments clearly indicated that distinct regions of CD4 interact respectively with gp120 and with class II MHC molecules. 相似文献
816.
Characterization of Schizosaccharomyces pombe minichromosome deletion derivatives and a functional allocation of their centromere. 总被引:8,自引:1,他引:7
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A 530 kb long Schizosaccharomyces pombe linear minichromosome, Ch16, containing a centric region of chromosome III, has previously been made. In the present study, we constructed a number of deletions in the right and/or left arms of Ch16, and compared their structure and behaviour with Ch16. The functional centromere, cen3, is allocated within a 120 kb long region which is covered by the shortest derivative, Ch10, and is comprised mostly of centromeric repeating sequences. The shortest minichromosome is stable in mitosis and the copy number control is apparently precise. In monosomic meiosis it segregates normally. In disomic meioses, however, the frequency of non-disjunction is very high, suggesting that it may not form a pair. The mitotic loss rate of one of the left-arm deletions, ChR32, which lacks a part of the centromeric repeating sequence, is the highest of all the deletions. This deletion also exhibits the highest precocious sister chromatid separation in meiosis I, suggesting that sister chromatid association might become weakened in ChR32. Our results indicate that the proper meiotic segregation of S.pombe minichromosomes is dependent upon the formation of a bivalent. S.pombe may not have the 'distributive segregation' found with Saccharomyces cerevisiae minichromosomes. 相似文献
817.
Nitroprusside differentially inhibits ADP-stimulated calcium influx and mobilization in human platelets. 总被引:3,自引:0,他引:3
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1. The effect of nitroprusside on cGMP concn., cAMP concn., shape change, aggregation, intracellular free Ca2+ concn. (by quin-2 fluorescence) and Mn2+ entry (by quenching of quin-2) was investigated in human platelets incubated with 1 mM-Ca2+ or 1 mM-EGTA. 2. Nitroprusside (10 nM-10 microM) caused similar concentration-dependent increases in platelet cGMP concn. and was without effect on cAMP concn. in the presence of extracellular Ca2+ or EGTA. 3. In ADP (3-6 microM)-stimulated platelets, nitroprusside caused 50% inhibition of shape change at 0.4 microM (+Ca2+) or 1.3 microM (+EGTA), aggregation at 0.09 microM (+Ca2+) and of increased intracellular Ca2+ at 0.02 microM (+Ca2+) or 2.1 microM (+EGTA). Entry of 1 mM-Mn2+ (-Ca2+) was inhibited by 80% by 5 microM-nitroprusside. 4. In ionomycin (20-500 nM)-stimulated platelets, nitroprusside (10 nM-100 microM) did not inhibit shape change or intracellular-Ca2+-increase responses, and only partially inhibited aggregation. 5. In phorbol myristate acetate (10 nM)-stimulated platelets, neither shape change nor aggregation was inhibited by 5 microM-nitroprusside. 6. The data demonstrate that nitroprusside inhibits ADP-mediated Ca2+ influx more potently than Ca2+ mobilization. Nitroprusside appears not to influence Ca2+ efflux or sequestration and not to affect the sensitivity of the activation mechanism to intracellular Ca2+ concn. or activation of protein kinase C. 相似文献
818.
The gene coding for the major birch pollen allergen Betv1, is highly homologous to a pea disease resistance response gene. 总被引:11,自引:1,他引:10
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H Breiteneder K Pettenburger A Bito R Valenta D Kraft H Rumpold O Scheiner M Breitenbach 《The EMBO journal》1989,8(7):1935-1938
Pollen of the white birch (Betula verrucosa) is one of the main causes of Type I allergic reactions (allergic rhinoconjunctivitis, allergic bronchial asthma) in Middle and Northern Europe, North America and the USSR. Type I allergies are a major threat to public health in these countries, since 10-15% of the population suffer from these diseases. BetvI, an allergenic protein with an Mr of 17 kd is a constituent of the pollen of white birch and is responsible for IgE binding in more than 95% of birch pollen allergic patients. Here, we report the complete nucleotide sequence and deduced amino acid sequence of a cDNA clone coding for the major pollen allergen (BetvI) of white birch. It is similar to the N-terminal peptide sequences of the allergens of hazel, alder and hornbeam (close relatives) but it has no significant sequence homology to any other known allergens. However, it shows 55% sequence identity with a pea disease resistance response gene, indicating that BetvI may be involved in pathogen resistance of pollen. 相似文献
819.
Quantitative determination of Ca2+-dependent Mg2+-ATPase from sarcoplasmic reticulum in muscle biopsies. 总被引:1,自引:0,他引:1
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The possibility of quantifying the total concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum was investigated by measurement of the Ca2+-dependent steady-state phosphorylation from [gamma-32P]ATP and the Ca2+-dependent 3-O-methylfluorescein phosphatase (3-O-MFPase) activity in crude muscle homogenates. The Ca2+-dependent phosphorylation at 0 degree C (mean +/- S.E.) was 40.0 +/- 2.5 (n = 6) and 6.2 +/- 0.7 (n = 4) nmol/g wet wt. in rat extensor digitorum longus (EDL) and soleus muscle, respectively (P less than 0.001). The Ca2+-dependent 3-O-MFPase activity at 37 degrees C was 1424 +/- 238 (n = 6) and 335 +/- 56 (n = 4) nmol/min per g wet wt. in rat EDL and soleus muscle, respectively (P less than 0.01). The molecular activity calculated from these measurements amounted to 35 +/- 5 min-1 (n = 6) and 55 +/- 10 min-1 (n = 4) for EDL and soleus muscle respectively. These values were not different from the molecular activity calculated for purified Ca2+-ATPase (36 min-1). The Ca2+-dependent 32P incorporation in soleus muscle decreased in the order mice greater than rats greater than guinea pigs. In EDL muscles from hypothyroid rats at a 30% reduction of the Ca2+-dependent phosphorylation was observed. The Ca2+-dependent phosphorylation in vastus lateralis muscle from three human subjects amounted to 4.5 +/- 0.8 nmol/g wet wt. It is concluded that measurement of the Ca2+-dependent phosphorylation allows rapid and reproducible quantification of the concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum. Since only 20-60 mg of tissue is required for the measurements, the method can also be used for biopsies obtained in clinical studies. 相似文献
820.
Summary Innervation of the ascidian branchial basket and other structures is demonstrated by staining for cholinesterase. Cholinesterase activity is not restricted to synaptic sites but is present throughout the neurons. Primary and secondary axonal bundles form a bilaterally symmetric innervation pattern around the large dorsal visceral nerve. These bundles continue to split into progressively smaller bundles as they course throughout the basket. Axons are suspended in a fibrous matrix and run within the blood sinuses on the atrial side of the basket. Stigmatal ciliated cells of the branchial basket are innervated by highly branched distal portions of neurons, whose cell bodies are located in the ganglion. Synaptic boutons, containing electron-lucent vesicles, are found at nearly all stigmatal ciliated cells. NiCl2backfills of the visceral nerve reveal a distinct population of central neurons, some of which presumably control ciliary arrest. 相似文献