Ultrastructural organization of epiphysis in rats under the action of electromagnetic fields and during mammary carcinogenesi.

Experiments conducted by the authors, as well as clinical studies, show that in addition to hormonal mis-balance, development of mammary gland cancer is significantly influenced by the action of low frequency electromagnetic fields on epiphysis. By reducing the production of melatonin it increases the risk of development of mammary gland tumors. The review of scientific literature indicates that pinealocytes are the main morphological substrate responsible for functional activity of pineal cells.

Household electromagnetic fields and breast cancer in elderly women.

The relationship between the rate of household low-frequency electromagnetic fields (EMF) and incidences of mammary tumors was studied in 1290 clinical case-records of female patients aged 60 and more over a period of 26 years, based on the materials of the Edith Wolfson Medical Center, Israel. The studied material was divided into two groups, each corresponding to a period of 13 years. Group I included patients with mammary tumors under observation from 1978 to 1990, who rarely used EMF-generating appliances.

The role of household electromagnetic fields in the development of mammary tumors in women: clinical case-record observations.

Background: The relationship between the exposure rates to household EMFs and incidences of mammary tumors has been studied in women based on the materials of the Edith Wolfson Medical Center, Israel.

Material/methods: 200,527 biopsy and surgery samples from a period of 26 years were analyzed. The material was divided into two groups: Group 1 included patients with breast tumors from 1978 to 1990 and Group 2 between 1991 and 2003.

Morphology of experimentally induced tumors of the sympathetic nervous system in rats.

Seventeen tumors of the sympathetic nervous system were discovered in offspring of rats exposed in utero at a single dose of 80mg/kg of N-nitrosoethylurea at the day 16-19 of pregnancy, and then to constant light regimen. These tumors were classified as follows: benign--ganglioneuroma (six cases) and malignant--ganglioneuroblastoma (four cases) and neuroblastoma (seven cases). The most frequent location was in the sympathetic trunk in the mediastinum and in the retroperitoneal space.

Transplacental effects of high fat diets on functional activity of the spleen and lymph nodes, cell kinetics and apoptosis in mammary gland tumors in female rat offspring.

We studied whether feeding pregnant female rats different high fat diets affects structural zones in the spleen and lymph nodes, involved in production of T and B cells, as well as cell kinetics and apoptosis in some offspring with mammary glands tumors. Rat mothers were fed either a 7% or 15% corn-oil or a 7% or 15% olive-oil diet. At four weeks of age, female offspring (n=10-15 per group) were transferred to 7% corn oil diet.

[Induction of tumors of the sympathetic nervous system in rats].

Benign (ganglioneuromas in 6 rats) and malignant (ganglioneuroblastomas--4) tumors and neuroblastomas (7) were induced in 17 animals by a single dose of 80 mg/kg ethylnitrosourea injected on days 18-19 of gestation. The animals were exposed to continuous lighting during gestation and lactation. Tumors of the sympathetic nervous system were at different stages of maturity.

The interspecies sensitivity to transplacental effects of carcinogens.

Childhood cancer is a serious problem in oncology. Because the period of high sensitivity to environmental effects has been suggested to be early in life, it is thought that a variety of influences on pregnant mothers might result in the development of neoplasia in offspring. Environmental and genetic factors have been shown to play a significant role in modifying transplacental tumorigenesis.

Effect of light/dark regimen on N-nitrosoethylurea-induced transplacental carcinogenesis in rats.

Pregnant females were randomly subdivided into three groups (24 rats per group) and kept at the 12:12 h light/dark regimen (group 1), at the constant light illumination (24 h a day, group 2) or at the continuous darkness (group 3). N-nitrosoethylurea (NEU) has been injected into the tail vein of all rats (80 mg/kg) on the 18-19th day of the pregnancy. After the delivery the lacting dams and their progeny during the lactation period (1 month after delivery) were kept also at the three different light/dark regimens.

[The effect of benz(a)pyrene on the thermal characteristics of DNA in vivo and in vitro].

Thermal properties of DNA-benz(a)pyrene complex and chromatin within liver cells in BALB/c mice and Macaca fascicularis monkeys after benz(a)pyrene administration were studied using a highly sensitive differential scanning microcalorimeter designed for investigations of dilute biopolymer solutions and complex biological systems. It was shown that benz(a)pyrene (BP) had different efforts on DNA in vivo and in vitro. It was established that at a molar ratio r < 0.

Biomarkers of individual susceptibility to carcinogens: application for biological monitoring.

In order to develop new markers of individual susceptibility to various human carcinogens, we studied some parameters of formation and metabolism of carcinogens, as well as DNA adducts formation and DNA repair in animals and humans. Following an i.p.

Individual levels of activity of O6-alkylguanine-DNA alkyltransferase in monkey gastric mucosa during chronic exposure to a gastrocarcinogen N-ethyl-N'-nitro-N-nitrosoguanidine.

The activity of a DNA repair enzyme, O6-alkylguanine-DNA alkyltransferase (AGT), was studied in gastric mucosa of 15 Macaca fascicularis monkeys before and during chronic oral exposure to the ethylating carcinogen N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) in order to investigate possible causes of inter-individual differences in susceptibility to its gastrocarcinogenic effect. A wide range of AGT activity (307-1903 fmol/mg protein, mean 695) was found before treatment and it decreased during the first year of exposure (means 627, 479 and 452 fmol/mg protein respectively at 6, 12 and 18 months after the beginning of the experiment). The carcinogenesis study is under way and to date four monkeys with low initial AGT level in gastric mucosa died of gastric cancer.

[Modifying effect of light and electromagnetic field on development of mammary tumors induced by N-nitrosomethyl urea in female rats].

Female rats aged I month and older were kept indoors in darkness, under lighting for 24 hours or exposed to ordinary lighting (light--12 hrs; darkness--12 hrs). Three weeks after the beginning of the experiment, they received N-nitrosomethyl urea (NMU) treatment in the dose of 50 mg/kg, intravenously, at weekly intervals, and were exposed to alternating 50 Hz (AMF) or static 0.2 oersted, (DMF) electromagnetic field radiation for 3 hrs, daily.

Biomarkers for individual susceptibility to carcinogenic agents: excretion and carcinogenic risk of benzo[a]pyrene metabolites.

In rats exposed to a single intraperitoneal dose of 200 mg/kg of the environmental carcinogen benzo[a]pyrene (BP) in sunflower oil, significant individual variations in excretion of the BP activation (BP-7,8-diol) and deactivation (3-OH-BP) derivatives were found. Most rats developed peritoneal sarcomas. Only the levels of BP-7,8-diol excreted in the urine correlated directly with the latency of tumor formation.

Tumor induction in monkeys after administration of dimethylhydrazine.

1,2-Dimethylhydrazine (DMH) was administered subcutaneously to nine Macaca fascicularis monkeys (6 males and 3 females) at doses of 16 mg/kg body weight, three times a month for two years. Colon cancer was detected in two male monkeys after total DMH doses of 1080 and 3696 mg (528 and 400 mg/kg body wt., respectively).

[The individual characteristics of the activity of the DNA-repair enzyme O(6)-alkylguanine-DNA alkyltransferase in the stomach of monkeys exposed to the gastric carcinogen N-ethyl-N1-nitro-N-nitrosoguanidine].

Variations in the activity of a DNA repair enzyme 0(6)-alkylgianine-DNA alkyltransferase (AGT) were studied in gastric mucosa samples obtained from 15 M. fascicularis monkeys chronically exposed to a gastrocarcinogen N-ethyl-N'-nitro-N-nitrosoguanidine. Marked interindividual difference in the enzyme activity before and in the course of the exposure was observed.

[Esophageal tumor induction in monkeys].

The experiment used eight monkeys who had received such esophagotropic carcinogens as ethyl ester of N-nitrososarcosine and methyl-N-benzyl-N-nitrosamine. The animals were followed for 4 years. The former agent failed to induce cancer where as 3 monkeys who had received methyl-N-benzyl-N-nitrosamine in the total dose of 600, 625 and 720 mg developed esophageal tumors (papilloma-2 and squamous cell carcinoma-1) at days 527, 725 and 880 after the start of treatment.

Low-frequency electromagnetic radiation enhances the induction of rat mammary tumors by nitrosomethyl urea.

Low-frequency electromagnetic fields enhance the induction of mammary gland tumors in rats using nitrosomethyl urea. The incidence of tumors depended on the duration of exposure to static (dc) and variable (ac) magnetic fields. Variable magnetic fields induced mammary gland cancer much more frequently than static ones.

[The effect of low-frequency electromagnetic fields on the development of experimental mammary tumors].

The paper discusses the effect of low-frequency electromagnetic fields on the development of nitrosomethylurea-induced breast cancer in rats. The occurrence, mean latency period and morphological pattern of breast malignancy was shown to depend upon duration of exposure to variable and static magnetic fields.

Morphology of experimental tumors of the sympathetic nervous system.

The morphology of experimental tumors of the sympathetic nervous system in rabbits and hamsters induced by administration of nitrose compounds and the use of modifying factors were studied. The tumors were localized in the mediastinum, retroperitoneal space, adrenals and kidneys. A predominant involvement of the female animals was observed.

[The induction of cancer of the large intestine in Macaca fascicularis monkeys with 1,2-dimethylhydrazine].

Continuous subcutaneous administration of 16 mg/kg body weight 1,2-dimethylhydrazine three times a month (total dose--1080-3696 mg) to Macaca fascicularis monkeys induced cancer invariably confined to the colon within 34-47 weeks. Biologic, clinical, histologic features and natural course of the tumor proved similar to those of its human counterpart.

Induction of renal tumors in cynomolgus monkeys (Macaca fascicularis) by prenatal exposure to 1,2-dimethylhydrazine.

Nephroblastomas were induced at an early age in two of six cynomolgus monkeys by prenatal exposure to 1,2-dimethylhydrazine. In one, the tumor of the right kidney had metastasized into the lower lobes of the lungs. By their histologic structure, development, and clinical course, the induced nephroblastomas were analogous to the Wilms' tumors often found in children.

Induction of gastric cancer in monkeys by N-methyl-N-nitro-N-nitrosoguanidine (MNNG).

N-methyl-N-nitro-N-nitrosoguanidine (MNNG) was administered to 9 Macaca fascicularis monkeys (7 males and 2 females) through a tube at a dose of 40 mg/kg body weight 3 times a month. Tumors of the pyloric part of the stomach were observed in 2 male monkeys after MNNG doses of 800 and 848 mg/kg body weight, with a latent period of tumor development of 49 and 50 weeks, respectively. Histologically, in one case the tumor was a solid carcinoma, and in the other it had a mixed structure showing alternating solid and signet ring cell carcinoma areas.