The competitive inhibition of [3H]-flunitrazepam binding by CL 218872 and propyl beta-carboline-3-carboxylate (PCC), non-benzodiazepine compounds that show differential affinities for benzodiazepine (BZD) receptor subtypes, was studied in the rat cerebral cortex and hippocampus at different temperatures of incubation. The potency of both inhibitors was significantly greater at 0° than at 37°C. The magnitude of temperature induced enhancement of potency may correlate with the pharmacological efficacy of compounds that interact with BZD receptors. Hill slopes for CL 218872 shifted from 0.52 to 0.97 in the cerebral cortex when incubations were performed at 0° and 37°C, respectively. Hill values for PCC changed from 0.68 to 0.93 under similar temperature conditions. These observations suggest the presence of a homogenous population of benzodiazepine receptors at physiological temperatures or the inability of CL 218872 and PCC to distinguish between receptor subtypes at 37°C. 相似文献
Summary The single and combined actions of transforming growth factor (TGF)-beta and osteogenin were evaluated with regard to induction
of colony formation and reexpression of the differentiated phenotype by dedifferentiated rabbit articular chondrocytes in
soft agarose under serum-free conditions. TGF-beta alone did not promote colony formation and induced accumulation of proteoglycans
and type II collagen at significantly lower levels than those induced by osteogenin. Although synergism between these two
growth factors occurred with respect to the induction of colony formation, their joint action on reexpression of the differentiated
phenotype was additive. Complex interactions between the two growth factors may explain the latter phenomenon. 相似文献
The colicin and immunity genes of plasmid ColE3-CA38 have been localized by characterization of bacteria carrying its cloned restriction fragments. They are within a 3.14-kb EcoRI segment, such that the immunity gene contains the KpnI site, and the colicin gene is adjacent to it within a 2.1-kb KpnI-HincII segment. The immunity gene and one end of the colicin gene are in the region of ColE3-CA38 which is not homologous to the closely related plasmid ColE2-P9. A 0.64-kb PvuI-EcoRI segment of the plasmid adjacent to that containing the colicin and immunity genes was found to augment colicin production on solid media, and also affected the morphology of clearing zones produced by the cells when used as indicators in overlays of stabs of colicin E2 or E7 producers. The 0.64-kb segment was required in its native orientation relative to the 3.14-kb EcoRI segment to cause its effects. 相似文献
Comparative electrophoretic phenotypes of 18 of the 32 species of the lizard genus Varanus have been determined for four proteins. The animals studied were representative of species from Africa, Israel, Southeast Asia and Australia. Malate dehydrogenase (A2) exhibited a single phenotype throughout. Lactate dehydrogenase (B4) showed four distinctive electrophoretic forms which grouped the various subgenera as follows: (1) Polydaedalus, Empagusia (African); (2) Psammosaurus (Israel); (3) three species of Varanus, V. gouldii, V. spenceri, V. mertensi (Australian); (4) Dendrovaranus, Indovaranus (Southeast Asian), other Varanus species, Odatria (Australian). Electrophoretic and previously reported karyotypic data were used to interpret the phylogenetic relationships as well as the mode and direction of evolution of these animals. In particular, the results questioned the reality of the subgenus Varanus as a taxonomic unit, since four distinct karyotypic forms and two LDH-B4 phenotypes were observed for these animals, of which one belongs to another subgenus. Serum albumin and carbonic anhydrase phenotypes were of little use in deciding phenotypic groupings. 相似文献
To explore the logic of evolutionary explanations of obesity we modelled food consumption in an animal that minimizes mortality (starvation plus predation) by switching between activities that differ in energy gain and predation. We show that if switching does not incur extra predation risk, the animal should have a single threshold level of reserves above which it performs the safe activity and below which it performs the dangerous activity. The value of the threshold is determined by the environmental conditions, implying that animals should have variable ‘set points’. Selection pressure to prevent energy stores exceeding the optimal level is usually weak, suggesting that immediate rewards might easily overcome the controls against becoming overweight. The risk of starvation can have a strong influence on the strategy even when starvation is extremely uncommon, so the incidence of mortality during famine in human history may be unimportant for explanations for obesity. If there is an extra risk of switching between activities, the animal should have two distinct thresholds: one to initiate weight gain and one to initiate weight loss. Contrary to the dual intervention point model, these thresholds will be inter-dependent, such that altering the predation risk alters the location of both thresholds; a result that undermines the evolutionary basis of the drifty genes hypothesis. Our work implies that understanding the causes of obesity can benefit from a better understanding of how evolution shapes the mechanisms that control body weight. 相似文献
New thiophene (2–13) and thienopyrimidine (15–27) derivatives have been synthesized. Twenty three compounds were screened against five cell lines namely; hepatocellular carcinoma (liver) HepG-2, epidermoid carcinoma (larynx) Hep-2, mammary gland (breast) MCF-7, human prostate cancer PC-3 and epithelioid cervix carcinoma HeLa. The results revealed that compounds 15,16,17,24 and 25 showed the highest antitumor activity against all tested cell lines compared to Doxorubicin. In order to explain the expected mode of action of the observed anticancer activity, compounds 15,16,17,24 and 25 were selected to screen their DNA binding affinity and enzyme inhibitory activity against DNA polymerase, thymidylate synthase and tyrosine kinase. The results revealed that the tested compounds showed good DNA binding affinity as well as good inhibitory activity against the three enzymes which might explain the observed anticancer activity of the target compounds. 相似文献
1. 1. The objective of this paper is to investigate the indoor environment from the viewpoint of interaction between physical environment and the human responses. The field survey has been conducted over 1 year.
2. 2. A continuous measurement has been carried out for 1 week and distribution of variables have been measured for 1 day.
3. 3. The attitude of workers was investigated by a questionnaire.
4. 4. As the result, average luminance represented more than 1000 lx in the new building, in contrast with less tha 300 lx in the existing building.
5. 5. There was a significant difference of the occupants' response to the light environment between the two buildings.
6. 6. Measured thermal conditions are on the edge of the ASHRAE comfort envelope in summer, and in the neighborhood of the lower dry limit of the envelope in spring.
7. 7. The occupants' evaluations were remarkably changed before and after the moving. The office environment is better than that of the factory.
A series of novel HIV-1 protease inhibitors has been designed and synthesized, which contained morpholine derivatives as the P2 ligands and hydrophobic cyclopropyl as the P1′ ligand at the meantime in this study, with the aim of improving the interactions between the active sites of HIV-1 protease and the inhibitors. Twenty-eight compounds were synthesized and assessed, among which inhibitors m18 and m1 exhibited excellent inhibitory effect on the activity of HIV-1 protease with IC50 value of 47 nM and 53 nM, respectively. The molecular modeling of m1 revealed possible hydrogen bondings or van der Waals between the inhibitor and the protease, worthy of in-depth study. 相似文献