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After disappointing results from all efficacy trials conducted to date, the field of microbicides research now faces substantial challenges. Poor coordination among interested parties and the choice of nonvalidated scientific targets for phase III studies have hampered progress and created mistrust about the use of microbicides as a method to prevent HIV-1 sexual transmission. Although new promising strategies are available, there will need to be serious reappraisals of how decisions are made to advance the next generations of candidates into clinical trials, and the use of appropriate animal models in this process will be critical.  相似文献   
134.
Seven phenolic acids and many nonphenolic organic acids, including large amounts of meta-hydroxy (3-hydroxy) benzoic acid and 3-hydroxy-1,5-benzene-dicarboxylic acid, were obtained from the organic polymer of the Murchison C2 chondrite upon oxidation with alkaline cupric oxide. The phenolic acids apparently were derived from phenolic ethers in the polymer, which in turn probably were formed from carbon monoxide and hydrogen by catalytic Fischer-Tropsch type reactions in the solar nebula. In contrast, terrestrial polymers such as lignin, humic acid, and coal yield mainly para-hydroxy (4-hydroxy) benzene derivatives by the same oxidation procedure.  相似文献   
135.
Ten strains of a new arbovirus belonging to the Bunyamwera group (Bunyaviridae) were recovered from field-collected Aedes albopictus mosquitoes in Potosi, Missouri. This evidence indicates that this species may serve as an arbovirus vector in the United States. The urban-suburban distribution, aggressive biting behavior, and broad viral susceptibility of Ae. albopictus may lead to the transmission of viruses of known public health importance and perhaps of viruses hitherto not transmitted to humans because of the feeding pattern of their usual vectors.  相似文献   
136.
A common mechanism of chromosomal translocation in T- and B-cell neoplasia   总被引:29,自引:0,他引:29  
The chromosomal breakpoint involved in the t(8;14)(q24;q11) chromosome translocation in the SKW-3 cell line, which directly involves the 3' flanking region of the c-myc gene, was cloned and sequenced. The breakpoint on chromosome 8 mapped to a position 3 kb 3' of c-myc while the chromosome 14 breakpoint occurred 36 kb 5' of the gene for the constant region of the alpha chain of the T-cell receptor (TCR). The translocation resulted in a precise rearrangement of sequences on chromosome 8 and what appears to be a functional J alpha segment on chromosome 14. Signal sequences for V-J joining occurred at the breakpoint positions on both chromosomes 14 and 8, suggesting that the translocation occurs during TCR gene rearrangement and that it is catalyzed by the enzymatic systems involved in V-J joining reactions. The involvement of c-myc in the translocation and the association of joining signals at the breakpoints provides a parallel to the situation observed in the translocations involving c-myc and the immunoglobulin loci in B-cell neoplasms and suggests that common mechanisms of translocation and oncogene deregulation are involved in B- and T-cell malignancies.  相似文献   
137.
A corticosteroid receptor in neuronal membranes   总被引:22,自引:0,他引:22  
Steroids may rapidly alter neuronal function and behavior through poorly characterized, direct actions on neuronal membranes. The membrane-bound receptors mediating these behavioral responses have not been identified. [3H]Corticosterone labels a population of specific, high-affinity recognition sites (dissociation constant = 0.51 nanomolar) in synaptic membranes from an amphibian brain. These binding sites were localized by receptor autoradiography in the neuropil, outside the regions of perikarya. The affinities of corticoids for this [3H]corticosterone binding site were linearly related to their potencies in rapidly suppressing male reproductive behavior. Thus, it appears that brain membranes contain a corticosteroid receptor that could participate in the regulation of behavior.  相似文献   
138.
Norepinephrine: release from brain by d-amphetamine in vivo   总被引:1,自引:0,他引:1  
After injection of H(3)-norepinephrine into the left lateral cerebral ventricle of cats, the lateral and third cerebral ventricles were perfused with an artificial cerebrospinal fluid. Addition of d-amphetamine to the perfusion fluid caused a significant increase in the concentration of H(3)-norepinephrine in the effluent.  相似文献   
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Scientists and surgeons   总被引:1,自引:0,他引:1  
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