Oncological characteristics of C57Bl/6JY mice

The oncological characteristic is presented for C57BL/6JY mice widely used in experiments. The mice over eighteen month had different spontaneous neoplasms among which hemoblastoses prevailed. The influence of sex, age and vaccination on the rate of spontaneous neoplasms in these mice is analyzed.     

The dependence of the carcinogenic effect on the concentration of N-nitrosodimethylamine in (CBA x C57Bl/6)F1 mice and noninbred mice

The relationship between the tumour frequency and nitrosodimethylamine (NDMA) concentration in drinking water was studied in the experiments involving 495 (CBA x C57Bl/6)F1 hybrid and 600 noninbred mice of both sex. At the NDMA concentrations of 0.04, 0.2, 1.0, 5.0 mg/l the tumour frequency was as follows: 21.6/26.2, 35.5/27.3, 57.4/56.4, 90.5/72.9% (20.0/20.0% in control) in hybrid mice; and 15.4/39.6, 18.2/43.5, 62.2/61.0, 76.5/87.5% (15.0/30.0% in control) in noninbred mice, respectively. In the given experiments the minimal effective NDMA concentration was 1.0 mg/l, and the maximal effective one--0.2 mg/l both for the hybrids and noninbred animals. The results of the research may be used for calculation of the MPC for NDMA.     

Elastase activity during growth and metastasis of tumors andthe pharmacological effects in C57Bl/6 mice

The elastase activity in malignant tumour tissues and lungs of C57B1/6 mice has been studied under growth and metastatic spreading of tumours and under some pharmacological influences (tryelin, cyclophosphamide). The highest elastase activity was revealed in mice with carcinoma 3LL, especially in the period of formation and appearance of metastases. Tryelin alone and in combination with cyclophosphamide reduces the elastase activity and inhibits the process of metastatic spreading in lungs.     

Spontaneous hepatomas in hybrid mice (CBA x C57Bl/6)F1

The spontaneous hepatomas of male mice (CBA X C57B1/6)F1 were studied using complex cytologic, histologic, immunochemical, and cytochemical methods. The AFP was detected in trace amount in the serum of tumour-bearing mice and in single cells of hepatomas. As a rule the hepatocarcinoma cells have the polymodal DNA distribution (2C-8C) with major peak of 4 C (in 18 out of 26 cases). More rarely the tumours with predominant diploid and octoploid cells were observed.     

Recombinant tumor necrosis factor promotes the formation of hematogenic metastases to the lungs of C57Bl/6 mice

The intravenous injection of the recombinant tumour necrosis factor (rTNF) to the C57BL/6 mice at a dose of 10(4) U 1.4 and 24 hours before or 4 hours after the intravenous inoculation of the LL (Lewis carcinoma) or MM-4 (B-16 melanoma) cells was found to be accompanied by a significant increase in the number of hematogenic metastases in the lungs of animals. The above rTNF effect could be considerably inhibited by the single heparin injection.     

Suppressor activity of bone marrow and spleen cells in C57Bl/6 mice during carcinogenesis induced by 7,12-dimethylbenz(a)anthracene

The nonspecific suppressor activity of bone marrow cells (BMC) and spleen cells (SC) of C57B1/6 mice was studied at 7,12-dimethylbenz(a)anthracene-induced carcinogenesis. It is established that in the latent period of the tumour development and with its appearance the suppressor activity of BMC decreases, while SC-increases. The activity of the BMC suppressor factor which is determined by the inhibition of proliferation of mastocytoma P-815 cells in vitro did not change significantly.     

Growth characteristics of adenocarcinoma 755 recurrences in C57Bl/6 and (DBA/2 X C57Bl/6) F1 mouse strains

Peculiarities of growth and recurrences of the adenocarcinoma 755 are studied in C57Bl/6 mice and hybrids (DBA/2 X +C57Bl/6)F1 after chemotherapy with cyclophosphamide and 6-mercaptopurine (6-MP). The growth rate of tumours was practically identical in the both mice strains. Growth rate of recurrences was slower in examined lines than in corresponding tumours. The obtained results showed that the antitumour effect of the drugs, in particularly of 6-MP, and the growth rate of the first and that of the second recurrences clearly depended on the tumour host strain.     

Changes in biological properties of malignant melanoma B-16 after transplantation to (CBA x C57Bl/6)F1 mice

The primary tumour properties are studied for their effect on the recurrent tumour growth and metastatic spreading after chemotherapy. Serial transplantation of the B16 melanoma to (CBA X C57Bl/6)F1 mice induced gradual changes in tumour malignancy. With an increase of the generation number the metastatic activity of hybrid mice rises and chemotherapeutic sensitivity lowers. The thirty-first and the fifty-fourth tumour generations after the chemotherapy metastasize earlier and the number of metastases increases more rapidly as compared with the recurrence of the primary tumour. The metastatic potential of recurrent tumours increases with the number of generations in hybrid mice.     

The content of tumor angiogenesis factor in the blood serum of C57Bl/6 mice during the growth and metastasis of transplanted tumors

The tumour growth and metastasis development after the primary tumour removal is accompanied by the appearance of the tumour angiogenesis factor (TAF) in blood. The TAF level directly correlates with the volume of tumour cell masses. These results confirm the present notions about the close correlation of the tumour growth and neovascularization and may be used to control the activity of neovascularization and malignant growth.     

Antineoplastic activity of combinations of cytostatics and dextran-ferrite administered to mice with leukemia P-388

Water solutions of adriblastin, dactinomycin, rosevin, methotrexate, cisplatin, sarcolysine, rubomycin, cyclophosphamide, 5-fluorouracil or ftorafur were combined with dextran ferrite. The obtained compositions were injected i.p. to BDF1 mice 24 hours after they were inoculated with one million of murine P388 leukemic cells. Antitumor activity was fully retained for each of these agents in combination with dextran ferrite.     

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.     

Proliferative activity of the uterine epithelium and mesenchymal elements in CBA-strain mice administered 1,2-dimethylhydrazine and estradiol dipropionate

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.     

Mutagenicity of natural-origin agents carcinogenic to humans

The current literature data on mutagenicity of human carcinogens of natural origin are reviewed. The high correlation is established between carcinogenicity and mutagenicity of this group of agents, all 10 agents are active in the Ames assay or in the cytogenetic tests, 7 of them are mutagenic in the Ames test and 8 in cytogenetic assays.     

用PIC16C57设计的高级密码锁

利用单片机PIC16C57设计了一种高级密码锁电路,给出了硬件电路图及部分软件流程图。该密码锁具有多级安全级别设置和记录非法入侵的功能。     

Genetic and oncological characteristics of CC57BR/Mv mice

The incidence of spontaneous malignancies in this line was 21.3% with predominance of haemoblastoses, adenomas of the lungs and liver. The study of the genetic character revealed homozygosis of mice CC57BR in all test genes.     

An evaluation of the toxic and antitumor action of farmorubicin administered to H-strain mice with Ehrlich ascitic cancer

The toxic and antitumour action of farmorubicin was investigated in experiments on mice. Data on the high antitumor activity were obtained after single application of the drug and at 5-day treatment of mice bearing the Ehrlich ascites tumour. It has been established that farmorubicin used in the tolerant dose was comparatively nontoxic--nonmyelotoxic. At higher doses the toxic damages manifested in different periods and depended on the employed doses. A decrease in the heart weight has permitted revealing the formorubicin-induced cardiotoxicity which was confirmed (after 5 injections of the preparation in a dose of LD 50) by electron microscopy.     

The mutagenicity of animal carcinogenic agents of natural origin

The current data from literature on the mutagenicity of carcinogens of natural origin are reviewed. A high correlation between carcinogenicity and mutagenicity of this group of agents is established.     

The regulation of splenocyte natural killer activity in C3HA mice in the early period after hepatoma 22a transplantation

A decrease of the natural killer activity (NKA) of C3HA splenocytes after transplantation of hepatoma 22a cells was connected to some extent with the suppressor action of macrophages and T-lymphocytes. Elimination of the macrophages from the splenocyte suspension led to the increase of NKA. Addition of the macrophages to the nonadherent cells resulted in the NKA inhibition to the level of nonfractionated splenocytes. T-cell elimination with anti-T-serum and a complement led to the increase of NKA as compared to NKA of the nonfractionated splenocytes.     

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).     

调谐比及非线性Bl对阻抗曲线的影响

研究了管道倒相式扬声器系统的阻抗曲线与调谐比及输入电压的关系,分析了阻抗曲线变化的原因,给出了调谐比对阻抗曲线峰值的影响,给出了非线性Bl对阻抗曲线峰值的影响。通过研究大信号情况下的阻抗曲线,给出了一种测量非线性Bl值的方法。理论分析与实验验证吻合很好。