Effect of the postnatal induction of persistent estrus on the realization of the transplacental action of DMBA in 1st- and 2d-generation rats

In rats of the first generation subjected to transplacental DMBA action with subsequent (at the age of 3 months) induction of persistent estrus, the incidence of tumours significantly increased, particularly, those of the nervous system and the mammary gland. Rats of the second generation with induced persistent estrus and not exposed to DMBA developed neoplasms of the nervous system and kidneys which were not observed in the intact control animals. This fact suggests persistence of DMBA transplacental carcinogenic effect in a series of generations.     

Effect of glucose on fetal weight and the transplacental blastomogenic effect of N-nitrosomethylurea in rats

The N-nitrosomethylurea (NMU)-induced transplacental blastomogenesis in rats was studied under the effect of pre- and postnatal glucose administration. On the 21st day of pregnancy NMU (20 mg/kg) was intraperitoneally administered to rats. From the 7th day of pregnancy experimental rats were treated with 10% glucose solution instead of drinking water, and during 1.5 months after delivery they and their progeny were given 5% glucose solution. The foetal weight in glucose-treated pregnant rate increased. A significant increase of tumour frequency was detected in the progeny of these rats. In male progeny tumours of the nervous system and kidneys typical of NMU effect prevailed and in females--tumours of other organs and tissues, particularly of the mammary gland, pituitary and hemopoietic system. Possible mechanisms of the modifying effect of glucose on the transplacental blastomogenic action of NMU are discussed.     

Influence of the polypeptide preparations cortexin and encephalin on the transplacental carcinogenic effect of N-nitroso-N-ethylurea in rats

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.     

The modifying influence of adenosylcobalamin on the transplacental carcinogenic effect of N-nitroso-N-ethylurea in organ cultures of the kidneys of DBA/2 mice

Transplacental effect of cobalamin coenzyme, adenosylcobalamin (Adocbl), on the carcinogenic action of N-nitroso-N-ethylurea (ENU) was studied in culture of the mouse embryonic kidney tissue by histoautoradiography. Coenzyme methylmalonyl-CoA-mutase, Adocbl, injected into DBA/2 mice in the prenatal period did not stimulate the proliferative activity of epithelial cells of the embryonic kidney. The treatment with Adocbl did not intensify hyperplastic changes common for the early stages of carcinogenesis. The frequency of hyperplastic changes mainly of focal proliferation in kidney explants with the combined administration was considerably lower than with the isolated action of the carcinogen and amounted to 8.7% and 21.5%, respectively (P less than 0.001).     

Effect of polypeptide factors of the thymus, pineal gland, bone marrow and anterior hypothalamus on the realization of transplacental carcinogenesis

The postnatal action of low-molecular polypeptide factors of thymus (FT), pineal gland (FP), bone marrow (FRM) and anterior hypothalamus (FAH) on transplacental carcinogenic effect of N-nitroso-N-ethylurea in rats was studied. Both FT and FP administrations decreased incidence and multiplicity of tumours and prolonged their mean latent periods. These drugs inhibited mainly the development of tumours of the spinal cord, kidneys and peripheral nervous system but not those of the brain. Both FBM and FAH had no significant influence on transplacental carcinogenesis. FT and FP anticarcinogenic effect is supposed to be due to their normalizing action on hormonal metabolic and immunological shifts arising in the body after transplacental administration of the carcinogen.     

Effect of ethanol on the hepatocarcinogenic action of N-nitrosodiethylamine in rats

It is shown that the administration of ethanol to male Wistar rats (3 g/kg by gastric tube 3 times a week for 2 months) before or at the beginning of the N-nitrosodiethylamine (NDEA) treatment (2.5 mg/kg 6 times a week in drinking water) reduces the hepatocarcinogenicity of NDEA. This was expressed macroscopically by less important neoplastic changes and biochemically by the higher glucose-6-phosphatase and lower glucose-6-phosphate dehydrogenase activities in the liver.     

Characteristics of the carcinogenic action of methyl(acetoxymethyl)nitrosamine and DNA repair in rats of different ages

A pattern of DNA methylation and carcinogenesis has been studied in young (3 month-old) and old (14 month-old) female rats following a single intravenous injection (13 mg/kg) of methyl(acetoxymethyl)nitrosamine (DMN-OAc). The incidence of various tumours as well as the incidence of tumours in some peculiar sites were found to be similar in young and old DMN-OAc-treated rats. The life time of old rats was less than that in young animals; the average period of tumour detection was also shorter in old rats. In both young and old animals the highest concentrations of methylated purines were found in lung and kidney DNA. However, the level of DNA methylation in old rats was higher than in corresponding tissues of young animals. Efficiency of O6-meG repair in methylated template DNA was found to be the highest in liver extracts of 1- and 12-month-old rats. Further, by the age of 2 years, the activity of O6-meGT decreased. The findings suggest that different age periods could be characterized by different efficiency of DNA alkylation, synthesis and repair.     

Effect of ascorbic acid on the hepatocarcinogenic action of N-nitrosodiethylamine in rats

It is shown that the ascorbic acid (AA) administration to Wistar male rats (50 mg per animal intraperitoneally 3 times a week) accelerates hepatocarcinogenesis induced by N-nitrosodiethylamine (2.5 mg/kg 6 times a week in drinking water). In this case the activity of glucose-6-phosphate dehydrogenase in liver increases, while that of glucose-6-phosphatase decreases.     

Comutagenic action of sodium selenite and caffeine on S. typhimurium TA 1535 with its subsequent treatment by N-nitrosomethylurea

The comutagenic activity of sodium selenite and caffeine was studied by the Ames test. Reproduction of S. typhimurium TA1535 for 4 h at 37 degrees C in the nutrient broth with sodium selenide (5 micrograms/ml) significantly increased sensitivity of bacterial cells to the mutagenic action of 2-3 mM N-nitrosomethylurea (NMU). When using threshold concentrations of NMU the potentiation of mutagenesis reached 625.2%. The addition of 0.19 mg/ml of caffeine to the nutrient medium also led (though the action was less pronounced) to an increase in sensitivity of bacterial cells to the NMU mutagenic action. Reproduction of S. typhimurium TA1535 in the medium containing sodium selenide and caffeine did not cause an increase in the frequency of spontaneous his+-revertant mutations.     

宽带大动态射频前端的设计与实现

介绍了1GHz~2GHz宽带大动态射频前端的设计和实现.大动态射频前端采用二次变频方案,实现了低噪声、大动态输出.通过合理的频率和电平配置,减小了混频非线性导致的组合干扰,降低了输出杂散、本振反向辐射.对中镜频信号有良好的抑制.可广泛的应用于侦察接收机和测向接收机.     

Comparative evaluation of the sensitivity to the carcinogenic action of N-methyl-N'-nitro-N-nitrosoguanidine of the epithelium of endophytic adenomatous-hyperplastic structures and of the epithelium of the gastric glands in rats

The experiments carried on 107 rats have shown that the sensitivity of the epithelium of experimental adenomatous diverticuli of the stomach to the action of N-methyl-N'-nitro-N-nitrosoguanidine is lower than that of the gland epithelium of the organ.     

The carcinogenic and genotoxic action of the substances in the exhaust gases from internal combustion engines]

The review presents physicochemical methods of the study of polycyclic aromatic hydrocarbons (PAH) and analysis of substances composing the exhausts of the internal combustion engines (ICE). High carcinogenic effect of the ICE exhausts due to the presence of nitro-PAHs was confirmed in the experiments with animals and the mutagenic effect was detected in the Ames test. A necessity to study carcinogenic and mutagenic effects of nitro-PAHs in a view to reveal their potential human health hazard is emphasized.     

Effect of carcinogenic substances on bone marrow cells in CBA mice

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.     

Effects of prostaglandins E2 and F2 alpha on the hypothalamo-hypophyseal-adrenal system and thyroid function in mice with Lewis lung carcinoma

It has been determined that prostaglandins E2 and F2 alpha being exogenously inoculated during the premetastatic period to mice with metastatic Lewis lung carcinoma in equal degree activate neurocytes of supraoptic and paraventricular hypothalamus nuclei, playing the important role in secretion of peptidergic hypophysial adrenal gland complex, but they exert unequal influence on pituitary body, adrenal cortex and thyroid apparatus. F2 alpha stimulates the pituitary body corticotrophic function, secretory function of spongiocytes and thyrocytes, identifies the thyroxin and triiodothyronine utilization, E2, on the contrary, does not influence these indices or reduces them. Obviously, the mentioned above differences between E2 and F2 alpha may be explained by their different influences on antimetastatic resistance.     

点扩散函数的一维数值计算及其MATLAB实现

通过应用复指数函数与Bessel函数的展开关系和将径向对称的光瞳函数展开成方位角的Fourier级数的方法,可以将衍射受限光学成像系统的点扩散函数的二维Fourier变换的计算转换为一维Fourier变换和一维Hankel变换的计算。并借助MATLAB软件在计算机上实现了编程计算。与二维Fourier变换计算方法相比,一维计算可以方便而清晰地获得像平面上任一确定方向的点扩散强度分布。与Fortran、Basic和C等编程计算语言相比,应用MATLAB语言编程计算,程序语言简洁,且大大降低了使用者对数学基础和计算机语言知识的要求,是进行科学与工程研究的高效工具。     

Partial realization of 2-D discrete linear system and 2-D Padeapproximation and reduction of 2-D rational transfer function

A method is presented for determining the unknown degree and system function of any 2-D discrete linear shift-invariant system characterized by a 2-D impulse response array, i.e., the coefficients of the formal double power series that are obtained by expanding a rational transfer function. Problems of 2-D Pade approximation and 2-D system reduction can be solved by the same method by making a reasonable assumption in the context of 2-D linear systems theory. The method is based on a 2-D extension of the Berlekamp-Massey algorithm for synthesis of linear feedback shift registers. It gives a novel approach to identification and approximation of 2-D linear systems and is comparable in efficiency with other methods for 2-D rational approximation based on the block Toeplitz and block Hankel matrices     

Effect of purified sewage on the composition of carcinogenic polycyclic aromatic hydrocarbons in the soil and vegetation

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.     

GPON系统EMS故障告警功能的设计与实现

首先介绍了千兆无源光网络(GPON)系统中网元管理系统(EMS,Element Management System)的 体系构架,然后简要分析了光网络单元在管理与控制过程中出现的告警情况,最后分析EMS故障管理模块的功能,并在此基础上设计并且实现了其故障管理模块中故障告警的监测与管理,完成了GPON网管中的一个重要部分的设计,为今后整个GPON网络管理系统的实现奠定了一定的基础.     

The carcinogenic effect of 5-bromodeoxyuridine and its amplification by x-rays in rats

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.     

Effect of the duration of administration of 1,2-dimethylhydrazine on its carcinogenic effect

The (CBA x C57Bl)F1 female mice were treated with weekly injections of 1,2-dimethylhydrazine (DMH) at a dose rate of 4.15 mg/kg of body weight during different time periods. Relations between the incidence of organ specified particular tumours depend on the total DMH dose. Incidence of haemoblastoses decreases with an increase in the DMH dose. Dose relationships of the tumour incidence are analyzed statistically by the method with intercurrent mortality corrections and carcinogen effect expressed by relations of the observed and expected numbers.