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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The damage and repair of rat brain DNA was studied in vivo after a single carcinogenic dose of ethylnitrosourea. Fragmentation of the brain DNA produced by this carcinogen was demonstrated on alkaline sucrose gradients. By the 24th hrs after treatment with ethylnitrosourea the single-strand damage to DNA was not completely repaired. As the highly differentiated cells of the central nervous system do not proliferate, it is possible that during brain carcinogenesis delayed repair of DNA of primitive cells might be needed for the formation of tumor anlage.
Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1975 Nov 25
PMID:Strand breakage in rat brain DNA and its repair induced by ethylnitrosourea in vivo. 12 17

The purpose of this study was to find whether gastric resection enhances the incidence of carcinoma in the remaining part of the stomach. 66 male Wistar rats were subjected to stomach resection according to the Billroth I or the Billroth II method. These rats, as well as control animals with intact stomachs, were fed the carcinogen N-Methyl-N'-nitro-N-nitrosoguanidine (NG). -- 25 of 66 animals developed carcinomas in the gastric remnant. Precancerous lesions were seen in 18 rats. The tumours were characterized histologically as adenocarcinomas. They were almost exclusively localized in the region of the gastroenteral anastomosis. The process of tumour formation in the resected stomach was completed within 17-31 weeks on continuous administration of NG in a concentration of 120 mg/l in the drinking water. In contrast to these findings, the development of cancer in the intact stomach required on average 41 weeks under the same conditions of NG administration. However, with regard to the incidence of malignant changes, no significant difference was observed between animals undergoing the Billroth I method and those undergoing the Billroth II method.--The results suggest that the resected stomach of the rat is more susceptible to induction of cancer than the intac one. Exposure of the resected stomach to an oral carcinogen induces carcinogenesis predominantly in the anastomotic region.
Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1976 Mar 19
PMID:Susceptibility of the resected stomach to experimental carcinogenesis. 13 24

After subcutaneous application of 0.5 mg 3,4-benzopyrene (BP) to Sprague-Dawley-rats on the 2nd day of life, 50% of the animals developed local fibrosarcomas after 250 +/- 70 days. Additional treatment with immunostimulating (BCG, albumin, vitamin A-acid) or immunodepressive agents (hydrocortisone, cyclophosphamide, methotrexat) which was started 6 days after birth and maintained throughout life, did not influence carcinogenesis with respect to tumor incidences and induction periods of tumors.
Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1976 May 03
PMID:Experimental investigations on the influence upon the chemical carcinogenesis. IInd communication: studies with 3,4-benzopyrene. 13 32

The 3,4-Benzopyrene (3,4-BP) carcinogenesis can be postponed or even completely inhibited in the presence of Putrescine (P). A single s.c. injection of 2.52 mg 3,4-BP in 0.5 ml tricaprylin on female mice (NMRI-strains, 4--5 weeks old, 20--25 g of body weight) induced locally malignant tumors (sarcomas and carcinomas) up to 97% of the animals treated. (132 mice with tumors from 136 animals treated). Animals injected with 3,4-BP plus 10 mg putrescine showed a considerable reduction of tumor incidence. Only three from 38 mice treated developed tumors (8%). The prevention of tumor could not be further improved with higher putrescine amounts, for example 15 mg and 20 mg P. These concentrations were moreover toxic to the animals. Histologically, the tumors developed in the presence of putrescine were rather poor in malignant cells and mitoses were also rare, in contrast to the usual 3,4-BP tumors which were rich in polymorph cells and mitoses.
Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1976 Sep 24
PMID:Prevention of 3,4-benzopyrene carcinogenesis in presence of putrescine. 13 15

The role of the kidney in carcinogenesis of the breast was studied in inbred Buffalo strain female rats ingesting 0.04% N-4-(4'-fluorobiphenyl)acetamide. The experimental groups consisted of intact female rats 5 weeks of age with both kidneys intact and female rats with a uninephrectomy. The incidence of carcinomas of the breast and the number of rats with multiple carcinomas, poorly and undifferentiated carcinomas was greater in rats with a uninephrectomy. N-4-(4'-fluorobiphenyl)acetamide and its active metabolites apparently were not excreted as rapidly in the rats with one kidney as in the animals with both kidneys intact. The metabolites were then returned to the breast and/or other organs.
Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1976
PMID:Increased incidence of carcinoma of the breast in Buffalo strain rats with one kidney ingesting N-4-(4'-fluorobiphenyl)acetamide. 13 24

Until now, carcinoma of the large intestine resected previously for benign disease has not been published. However an increasing number of patients resected for Crohn's disease, diverticulitis or trauma may reach nowadays a high lifespan. On the other hand, it is known that the gastroenteral anastomosis is predisposed to cancer development. In this study, the question of whether the large intestine following colotomy or ileotransversostomy is sensitive to carcinogenesis is examined. Male Wistar rats, subjected to colotomy or resection and ileotransversostomy, were treated weekly by subcutaneous injection of 1,2-dimethylhydrazine (12 mg/kg body weight) for seven weeks. The animals were killed 54 weeks after the first injection. At autopsy, 21 out of 29 operated rats had developed adenocarcinomas of the remaining colon. Intact control animals had the same incidence of malignant degeneration of the large bowel. When the anastomosis is chronically irritated by inflammation or by formation of a diverticulum, development, of carcinoma near the stoma was observed. This was the case in three rats of 28 animals. The results demonstrate that the resected colon of the rat is not more sensitive to experimental carcinogenesis than the intact one.
Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1977 May 20
PMID:Experimental carcinogenesis in the resected colon of the rat. 14

Histochemical activity of acid DNAse, intensity of nucleic acid staining and histological alterations in mouse interfollicular epidermis (I.F.E.) were investigated after a single dose or after chronic topical administration of two hyperplastic agents, of which one (croton oil) was a potent tumor promotor, and the other one (podophyllin) did not promote skin carcinogenesis. Podophyllin induced intense uniform I.F.E. hyperplasia without any proliferation of poorly differentiated basal cells, without increased nucleic acid staining and without any appreciably decreased acid DNAse activity. On the other hand, croton oil (as well as TPA) produced almost immediate, distinct hyperplasia of poorly differentiated basal cells with increased intensity in the staining of both nucleic acids and nearly complete deficiency in acid DNAse activity. Similar histochemical and histological patterns were observed at the sites of wounding hyperplasia in untreated control mice. Such wounding hyperplasia was thought also to be a tumor promoting factor. It was suggested that the decrease in acid DNAse activity which occurred almost immediately after administration of potent tumor promoters and which could not be induced by a hyperplastic agent without tumor promoting action may have a particular importance in the mechanisms of tumor promotion.
Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1977 Nov 18
PMID:Induction of the deficient acid DNAse activity in mouse interfollicular epidermis by croton oil as a possible tumor promoting mechanism. 14 59

Breast cancer is the result of a multistage carcinogenic process. Initiation, promotion, dependency and autonomy make up a sequence of experimentally distinguishable phases of this process. Progression--the transition from dependency on hormonal support to autonomy--is demonstrable clinically. High-affinity saturatable estrogen binding by breast cancer cytosols distinguishes endocrine-responsive mammary neoplasms from autonomous breast cancers. Approximately 70% of neoplasms containing estrogen-recepor protein at a level of 2.5 femtomoles per mg. protein or higher regress after endocrine ablation (ovariectomy in premenopausal women; adrenalectomy or hypophysectomy in postmenopausal women). Only about 5% of neoplasms lacking the receptor will respond to these maneuvers. Estrogen-receptor content also predicts clinically for estrogen and androgen responsiveness, and experimentally for prolactin dependency. Fifty per cent of primary breast cancers in women are receptor-positive. Normal breast tissue and benign breast lesions characteristically lack receptor protein. The receptor proteins appear to be induced in neoplastic cells during mammary carcinogenesis in endocrinologic settings where non-cancerous breast cells do not contain free receptor in large amounts and fail to manifest endocrinologic growth stimulation. Implications of these findings for endocrinologic management of disseminated mammary cancer, adjuvant therapy, and breast cancer prevention are discussed.
Am J Clin Pathol 1975 Dec
PMID:Endocrinology in cancer of the breast. Status and prospects. 17 80

With the aim of expanding knowledge on the pathogenesis of nephroblastomata, an embryological organ culture system (Grobstein, 1956) was tested for its applicability to in vitro carcinogenesis experiments by using murine sarcoma virus (MSV-M) and 3-methylcholanthrene (MCA). Treatment of CBA/H-T6 mouse metanephrogenic mesenchyma with MSV-M at the pretubular stage neither disturbed the glomerulogenesis nor induced rapid malignant transformation. Treatment of the same tissues with MCA considerably inhibited the glomerulogenesis but failed to also reduce rapid malignant transformation. However, one MSV-M, one MCA and two untreated cultures showed malignant transformation after prolonged survival in vitro and produced different histological types of tumours upon transplantation into newborn CBA/H-T6 mice.
Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1976 Jan 02
PMID:Attempts to induce tubular deformations and subsequent mixed tumours from organotypic cultures of mouse renal mesenchyma. 17 92

Four simultaneous dosages of the ethylnitrosourea precursors, ethylurea and sodium nitrite, were administered intragastrically to pregnant hamsters at 100 mg/kg and 50 mg/kg respectively, from the 12-15th days of pregnancy. The treatment induced multiple neurogenic tumors of the peripheral nervous system in the offspring. Female progeny developed a greater incidence and multiplicity of peripheral nervous system tumors with significantly shorter latencies than males, thus establishing evidence that the tumors were age and sex dependent. The tumors presented varied morphological patterns and upon transplantation, grew regularly, exhibiting their malignant nature. The possible influence of estrogenic hormones on the development and growth of peripheral nervous system tumors and comparative aspects of the relationship between prenatal and postnatal carcinogenesis with regard to the ensuing tumor spectra as a consequence of exposure to the same chemical agent, are discussed.
Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1976 Mar 19
PMID:Transplacental effects of ethylnitrosourea precursors ethylurea and sodium nitrite in hamsters. 17 12


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