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1.
CBA, C3HA, C57Bl, Balb/c and DBA female mice received 20 subcutaneous weekly injections of 1,2-dimethylhydrazine in the dose of 8 mg/kg body weight. Estrous cycles were studied in vaginal smears taken 5, 10, 15 and 20 weeks after the 1st DMH injection. In CBA strain susceptible to DMH induction of uterine sarcomas a persistent estrus was observed in 50% of mice after 5 to 10 DMH injections. In C3HA, C57B1, Balb/c and DBA strains resistant to the DNH induction of uterine sarcomas persistent estrus was not observed; the majority of these mice retained a normal estrus cycle. Persistent diestrus which was absent in susceptible CBA mice was found in these resistant strains. No CBA females with a normal estrous cycle were observed after the beginning of DMH treatment. The differences in the estrous cycle found in the mouse strains treated with DMH may partly explain the observed strain differences in the susceptibility to the DMH induction of uterine sarcomas.  相似文献   

2.
Administration of ascorbic acid (0.3% in drinking water) inhibited the promoting effect of estradiol dipropionate on the 1,2-dimethylhydrazine-induced uterine sarcomogenesis in CBA mice. However administration of sodium ascorbate intensified the promoting effect of estradiol on the uterine sarcomogenesis, as evidenced by the shortening of the periods of tumour incidence.  相似文献   

3.
The results of experiments on the 1,2-dimethylhydrazine (DMH) induction of epithelial renal tumours in CBA male mice are presented. The dose-response study shows a sharp increase (from 5 to 75%) of the epithelial renal tumour incidence in the range of 2, 4 and 8 injections of DMH. Higher doses induce a decrease of the tumour incidence due to the early death caused by other tumours. DMH is shown to be the most powerful renal carcinogen in mice. Serial sacrifice of mice after 5 injections of DMH is a convenient model for the study of renal carcinogenesis in mice. Main histological types of epithelial renal tumours are illustrated.  相似文献   

4.
1,2-dimethylhydrazine (DMH) inducing uterine sarcomas in CBA mice was studied for its prolonged effect on the level of specific binding and affinity to the estradiol receptors in cytosol fraction of CBA mice uterine tissue. It is shown that the dissociation constant 3H-estradiol-17 beta with a receptor protein in the cytosol of uterine tissue of DMH treated mice was slightly higher than in control mice. The theoretical number of the ligand binding sites with receptor protein and the level of free binding sites of estrogen receptors were higher in DMH-treated animals than in control mice during the whole period of observation.  相似文献   

5.
5-bromodeoxyuridine (BUdR) injected to rats in the neonatal period is shown to produce a pronounced carcinogenic effect which brings about the appearance of various benign and malignant tumours. Exposure of females to X-ray total-body irradiation (1.5 Gy) was followed by intensification of the carcinogenic effect of BUdR. Assuming that this pyrimidine analog reacts solely with DNA substituting thymidine during DNA synthesis and induces point mutations due to tautomerization, the data obtained demonstrate the possibility of tumour induction by a selective DNA perturbation.  相似文献   

6.
Difference have been demonstrated in proliferative responses of epithelial and mesenchymal cells in the uterus of CBA mice under administration of 20 weekly subcutaneous injections of 1,2-dimethylhydrazine (DMH) and estradiol dipropionate (EP) separately and in combination (DMH+EP). The proliferative pool (Pc) of uterine glands epithelium increases under the effect of EP and decreases under the effect of both DMH and DMH+EP. The proliferative pool of mesenchymal cells increases under the effect of DMH, EP, and DMH+EP 5 to 10 weeks after the beginning of their administration, then it decreases. But percentage of DNA synthesizing cells in the regions of hyperplasia and the tumour formation enhances significantly by the 15th to 20th weeks after the beginning of DMH+EP administration.  相似文献   

7.
The results of two experiments on the transzygotic transfer of the nitrosoethylurea (NEU) carcinogenic effect are presented. In the first experiment female rats received 60 mg/kg b. w. of NEU at 16, 18 and 20th day of the pregnancy. Their F1 descendants developed multiple tumours of the nervous system after a short latency (up to 40 weeks). The rats of F2, F3, F4 and F5 generations which were not in a direct contact with NEU developed a statistically higher incidence of tumours occurring spontaneously (those of mammary gland, pituitary, and haematopoietic tissue). However, the incidence of nervous system tumours was at the level of controls. In the second experiment male rats received 80 mg/kg b. w. of NEU and then were mated with untreated females. The incidence of the nervous system tumours in the descendants of treated males was somewhat higher than in the controls. The manifestations and mechanisms of the transzygotic effect are discussed.  相似文献   

8.
已有报道~[1~3]说明激光工作者的外周血染色体畸变率及姊妹染色单体交换率明显增高。  相似文献   

9.
The effect of some carcinogenic and non-carcinogenic agents on the content of CFUs and frequency of micronuclei (Howell-Jolly corps) in polychromatic erythrocytes of bone marrow cells was studied in CBA mice. Benzene administration decreased the content of CFUs in bone marrow cells, but this effect is considered to be rather a sign of its hematotropic than carcinogenic action. Changes in the CFUs amount induced by chrysotile-asbestos and quartz DQ-12 action were insignificant. All investigated carcinogenic agents (benz(a)pyrene, asbestos and benzene) significantly increased the number of micronuclei in polychromatic erythrocytes of bone marrow in mice.  相似文献   

10.
It is proved in experiments with the interrupting and twenty-four hour inhalations and peroral use of nitrosodimethylamine on the Wistar and white rats, that blastomogenic effect is submitted to the dose-effect dependence. On the whole the tumour incidence is determined by a total dose of carcinogen but its size may vary to a considerable extent depending on the regime of nitrosodimethylamine delivery. The daily and single doses of carcinogen are of great importance. Relatively high daily doses introduced within a short period of time cause a greater effect than low doses introduced within a larger period of time. The greater blastomogenic effect is caused by a longer peroral introduction of the same daily dose.  相似文献   

11.
Using the Scatchard analysis of 125J-EGF binding it was shown that plasma membranes of gastric and small intestinal epithelial cells contain approximately 20 times less EGF-receptors (EGF-R) than liver cells. Investigation of the phosphorylation activity of EGF-R-kinase was performed in vitro on plasma membranes from intestine, intestinal tumours and liver cells. The main protein phosphorylated at tyrosine in the tumours was p34 but the intensity of EGF-R autophosphorylation and its total protein-tyrosine kinase activity were reduced (as compared with small-intestinal and liver cell membranes). In the tumours of the colon induced by DMH an increased binding of 125J-EGF has been observed as compared with normal colonic enterocytes and increased number of EGF-R was clearly demonstrated. Phosphorylation of p34 in the intestinal membranes proceeds much more intensively than that of EGF-R.  相似文献   

12.
Cortiphen and cyclophosphamide were studied for their effect on the mixed uterus sarcoma induced primarily by 1,2-dimethylhydrazine and oestradiol-dipropionate in CBA mice and its transplants. Their inhibitory action on the growth of these tumours is established.  相似文献   

13.
The polypeptide preparations cortexin and encephalin from grey and white substances of the cattle brain injected in the postnatal period are studied for their effect on the development of the nervous system and kidney tumours in rats induced transplacentally by N-nitroso-N-ethylurea. The two preparations decreased both the incidence and multiplicity of the brain tumours. It is supposed that the anticarcinogenic effect of these preparations is due to their normalizing action on the differentiation and proliferation of the brain glia cells.  相似文献   

14.
Choice of stimulus parameters is an important consideration in the design of neural prosthetic systems. The objective of this study was to determine the effect of rectangular stimulus pulsewidth (PW) on the selectivity of peripheral nerve stimulation. Computer simulations using a cable model of a mammalian myelinated nerve fiber indicated that shorter PW's increased the difference between the threshold currents of fibers lying at different distances from an electrode. Experimental measurements of joint torque generated by peripheral nerve stimulation demonstrated that shorter PW's generated larger torques before spillover and created a larger dynamic range of currents between threshold and spillover. Thus, shorter PW's allowed more spatially selective stimulation of nerve fibers. Analysis of the response of a passive cable model to different duration stimuli indicated that PW dependent contributions of distributed sources to membrane polarization accounted for the observed differences in selectivity  相似文献   

15.
The dependence of the microhardness H of macroporous silicon layers formed on the duration t an of electrochemical anodization at a constant current density of J = 20 mA/cm2 is studied. It is shown that the nonlinear run of the dependence H(t an) is due to the influence exerted on the microhardness not only by the surface density of pores, but also by the single-crystal base at L < 10h, where L and h are the thickness of the porous layer and the depth of indenter penetration, respectively.  相似文献   

16.
Concentrations of benz(a)pyrene (BP) and 15 other polycyclic aromatic hydrocarbons (PAH) in soil with forage plants (lucerne) irrigated by biologically purified mixed domestic and industrial (coke-chemical) sewage from collection pond did not exceed those in control soil (irrigated by relatively clean fresh water) and were lower than in nonirrigated one, which is due, probably, to PAH oxidation by soil-proper microflora activated in humid soil polluted by PAH. BP content in control and experimental samples of lucerne coincide within +/- 25% limits.  相似文献   

17.
The modifying role of adsorption activity, fibre size, fibrogenicity, carcinogens of other classes and of some noncarcinogenic compounds in asbestos carcinogenesis have been considered. It is supposed that the modifying factors play a dominant role in asbestos blastomogenicity. The removal of these factors is an important method for tumours prophylaxis in asbestos workers.  相似文献   

18.
The main effect of switching a magnetoplasma medium is to split the source wave into new waves whose frequencies are different from the source wave. In addition, if the source is a monochromatic pulse, the duration of the pulse is altered. Analytical expressions for the pulse duration of the various characteristic waves in a magnetoplasma are derived. The variations of the pulse duration with the source frequency, the plasma frequency and the cyclotron frequency are illustrated. The principle of the change in the pulse duration may be used to diagnose dynamically the time — varying parameters of a magnetoplasma medium.  相似文献   

19.
The radioimmunological and radioreceptor methods have been used to show that sialadenectomy leads to the stable decrease of the epidermal growth factor (EGF) concentration in saliva and blood serum. The mean number of colon tumours per rat was significantly lower among the rats which had been sialadenectomized before injections of the carcinogen, than in the control. But a sharp stimulation of carcinogenesis in the duodenal mucosa was observed after sialadenectomy. The production of the alpha-transforming growth factor with the EGF-competing activity for the EGF-receptors was found in the chemically-induced rat colon tumours.  相似文献   

20.
Wolfson  A. A.  Mokhov  E. N. 《Semiconductors》2009,43(3):400-402

Variation in the structural and morphological features and luminescent characteristics of thick epitaxial GaN layers grown by the sublimation sandwich method with the duration of the crystallization process has been studied. This was, in particular, done by means of scanning electron microscopy in the secondary-electron and color-cathodoluminescence modes. It was found that rather high-quality GaN layers with a thickness of up to 0.5 mm can be grown in a time of about 1.5 h, with their surface hardly exhibiting any luminescence in the visible spectral range. However, making the growth process longer in order to obtain thicker layers impairs the quality of a crystal being grown, which is accompanied by an increase in the intensity of cathodoluminescence from its surface layer in the visible (predominantly yellow) region of the spectrum. Reasons for the poorer quality of GaN layers in this case are discussed. It is suggested that, as the evaporation rate from the source decreases, the amount of active nitrogen near the growth surface becomes lower.

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