Change in the metabolism and toxic effect of benz(a)pyrene by its metabolites and a series of phenols

Effects of some phenols and polycyclic aromatic hydrocarbon derivatives on benz(a)-pyrene metabolism have been studied in the microsomal system isolated from the mouse embryonic cell cultures. The rate of benz(a)pyrene metabolism was shown to depend on the structure and concentration of the agents added. The toxic effect of benz(a)pyrene was summed up with that of either agent studied (except ionol) added simultaneously to the cell culture.     

Effect of uncoupling agents and benz (a) pyrene metabolites on respiration in L cells and normal mouse embryonal fibroblasts

A method is proposed for a polarografic study of the respiration of cell suspensions obtained from monolayer cultures of L-cells and from normal embryonic fibroblasts of mice (C3HA line). 6-hydroxybenzo(a)pyrene (6-OHBP). The metabolite of the carcinogenic hydrocarbon benzo(a)pyrene, was shown to be a strong uncoupler of of oxidation and phosphorylation of cell suspensions. Its effect was influenced by the presence of calf serum in the incubation media. Possible relationships between the toxic effect of 6-OHBP on monolayer cultures of normal and tumor cells, and its effect on cell energetics are discussed.     

Fracture of boron particles in 2219 aluminum as a known acoustic emission source

Boron particles have been introduced into 2219 aluminum using a powder metallurgy approach. The only sources of detectable acoustic emission during deformation of the resulting material are decohesion of the boron particles from the matrix and particle fracture. The energy released by fracture of the boron particles during deformation was estimated from elasticity theory using measured diameters of the individual fractures. The energy in the acoustic emission signals produced by particle fracture (the integral of the signal voltage squared) was found to be proportional to the fracture energy released. Fracture energies were in the range 1–7 ergs for the larger fractures. The relation found between fracture energy and acoustic emission signal energy can be used to estimate the energy released by other comparable acoustic emission sources in samples of similar geometry from their acoustic emission signals. During the course of the acoustic emission measurements, the response of an rms voltmeter to an individual acoustic emission signal was found to be proportional to the energy of the signal.     

Cryoprecipitates as a source of fibrinogen in treatment of disseminated introvascular coagulation (DIC)

Cryoprecipitates, in addition to containing factor VIII, contain about one third of the fibrinogen in the plasma from which they were derived. This fibrinogen is functional, as established by successfully preparing two congenital hypofibrinogenemics for major surgery by infusing cryoprecipitates. Cryoprecipitates and platelet concentrates are also used for patients with low levels caused by disseminated intravascular coagulation (DIC). We feel that these patients benefit not only from the factor VIII in the cryoprecipitates, but from the fibrinogen, which adds its support to the fibrinogen in platelet infusions, plasma, and whole blood. Such support makes it possible to heparinize such patients more heavily than would be safe without such preparation. The authors report three patients with severe and life-endangering DIC who were heavily heparinized, and supported with cryoprecipitates, as well as other blood fractions. Response to this therapy was excellent.     

Carcinogenicity of benzo-ring derivatives of benzo(a)pyrene on mouse skin

Benzo(a)pyrene (BP) and several benzo-ring derivatives of BP were tested for carcinogenic activity in mice by topical application of each compound once every 2 weeks for 60 weeks. Chronic treatment of C57BL/6J mice with (+/-)-trans-7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene (0.025 to 0.10 micronmole/application) indicated that the dihydrodiol was slightly more active as a complete carcinogen than the parent hydrocarbon BP. 7,8-Dihydroxy-7,8,9,10-tetrahydro-benzo(a)pyrene, a compound related to (+/-)-trans-7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene but which lacks the double bond at position 9,10, was inactive as a carcinogen on mouse skin. These results indicate the importance of the double bond at position 9,10 for the carcinogenic activity of (+/-)-trans-7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene. Chronic treatment of mice with -.4 micronmole of the highly mutagenic (+/-)-7,beta,8alpha-dihydroxy-9alpha, 10alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene, (+/-)-7beta,8alpha-dihydroxy-9beta, 10beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene, or 9,10-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene every 2 weeks for 60 weeks resulted in tumor incidences of 0, 8, and 4%, respectively, whereas BP at this dose caused a 100% tumor incidence. The high reactivity of the three epoxides may account for their inactivity or their weak carcinogenic activity on mouse skin.     

火花源原子发射光谱仪的维护

对Baird FSQ火花光谱仪光路系统存在的问题进行了分析研究,并提出具体解决方法.经实施获得了良好的效果,使仪器工作性能基本得以恢复.     

Identification of benz(othi)azepine-binding regions within L-type calcium channel alpha1 subunits

To identify the binding domain for diltiazem-like Ca2+ antagonists on L-type Ca2+ channel alpha1 subunits we synthesized the benzazepine [3H]benziazem as a novel photoaffinity probe. [3H]Benziazem reversibly labeled the benzothiazepine (BTZ)-binding domain of partially purified skeletal muscle Ca2+ channels with high affinity (Kd = 12 nM) and photoincorporated into its binding domain with high yield (>66%). Antibody mapping of proteolytic labeled fragments revealed specific labeling of regions associated with transmembrane segments S6 in repeats III and IV. More than 50% of the labeling was found in the tryptic fragment alanine 1023-lysine 1077 containing IIIS6 together with extracellular and intracellular amino acid residues. The remaining labeling was identified in a second site comprising segment S6 in repeat IV and adjacent residues. Unlike for dihydropyridines, no labeling was observed in the connecting IIIS5-IIIS6 linker. The [3H]benziazem photolabeled regions must be in close contact to the drug molecule when bound to the channel. We propose that the determinants for high affinity BTZ binding are located within or in close proximity to segments IIIS6 and/or IVS6. Therefore the binding domain for BTZs, like for the other main classes of Ca2+ antagonists, must be located in close proximity to pore-forming regions of the channel.     

The liver as a source of somatomedin

Somatomedin (Sm) activity (measured by [35S] utake in chick embryo cartilage) was determined in serum samples simultaneously drawn from the hepatic vein, portal vein, femoral artery and demoral vein of seventeen anaesthezied normal adult dogs). A pool of human serum was taken as reference (Sm = 1 U/ml). Sm levels in the peripheral vein of dogs were 0.38 +/- 0.03 U/ml). Mean +/- SEM). Sm activity was greater in the hepatic vein (0.48 U/ml) than in the other vessels (0.36, 0.39, 0.38 U/ml), and the paired differences were significant (P less than 0.002 to P less than 0.05). In three dogs which received b-GH (20 IU/day), the Sm levels were significantly increased after nine days in the femoural vein (P less than 0.05) and in the hepatic vein (P less than 0.05). The validity of the assay is discussed; a possible interference of NEFA in the assay is eliminated. The difference of Sm levels between hepatic and portal veins, related to hepatic flow measured in seven of these dogs, indicate an important production of Sm by the liver.