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Biomedical subjects

P Pour

Publications and source records attributed to P Pour.

At least 73 records · Page 4Linked to original sources
PubMed1976

Comparative studies of neoplastic response to a single dose of nitroso compounds. 5. The effect of dimethylnitrosamine in Swiss, ASW/SN and A-strain mice.

The tumorigenic effect of dimethylnitrosamine given once at 5 different dose levels was compared in adult Swiss, ASW/SN and A-strain mice. Considering the overall tumour incidence, at the highest dose level an increase was found in Swiss and ASW/SN mice, but not in A-strain animals. However, the effect of treatment was unequivocal for lung neoplasms. The rate of carcinomas rose significantly in all 3 strains, although a clear dose response-relationship could be established only in Swiss and ASW/SN mice. A dose-dependent effect for adenomas was found solely in Swiss mice.

Adenoma↗
PubMed1976

Transplacental effects of nitrosamines in Syrian hamsters: I. Dibutylnitrosamine and nitrosohexamethyleneimine.

The transplacental carcinogenic effects of dibutylnitrosamine (DBN) and nitrosohexamethyleneimine (N-6-MI) were examined in Syrian hamsters. A proportion of both substances reached the fetal tissue unaltered. No macroscopic malformations were observed in the offspring; however, postnatal mortality was high. Respiratory tumours were found upon histologic examination of surviving animals. Single doses of 30 mg/kg body weight (b.w.) DBN and 2 doses of 10 mg/kg b.w. N-6-MI did not induce tumours in the P-generation, but led to a low tumour incidence in the F1-generation (DBN, 7.0%, N-6-MI, 2.0%). Treatment for up to eight days during the second half of pregnancy led to a higher tumour incidence in the P-generation (DBN, 22%; N-6-MI, 20%), than in the F1-generation (DBN, 6.0%; N-6-MI, 10%).

Animals↗
PubMed1976

Histogenesis of tumors from the nasal cavities induced by diethylnitrosamine.

Chronic subcutaneous (s.c.) or single intravenous (i.v.) injections of diethylnitrosamine (DEN) to gerbils (Meriones unguiculatus) led to the induction of carcinomas of the nasal cavities in a high incidence. These neoplasms were multifocal in origin, frequently showing mixed cellular patterns of the following cell types: large cuboidal cells, nonciliated columnar cells, ciliated columnar cells, small cells, and squamous epithelial cells. No sensory cells of the olfactory mucosa or neurofibrillar differentiations were found in these neoplasms, although several showed rosette- and pseudorosette-like formations. Dose and route of administration seemed to influence the site of origin and the patterns of cellularity of these tumors. Whereas chronic s.c. injections resulted in carcinomas of the olfactory region, being mostly composed of large cuboidal cells, single i.v. injections led to the development of carcinomas mainly originating from the respiratory-olfactory mucosal junction and composed preferentially of nonciliated and ciliated columnar cells.

Adenocarcinoma↗
PubMed1976

A further pancreatic carcinogen in Syrian golden hamsters: N-nitroso-bis(2-acetoxypropyl)amine.

Weekly subcutaneous injection of N-nitroso-bis(2-acetoxypropyl)amine (BAP) for 20 weeks to Syrian golden hamsters induced pancreatic neoplasms in 50% of the animals, as early as 15 weeks from the start of treatment. The carcinogenic potency and organotropic spectrum of BAP were similar to those of N-nitroso-bis(2-hydroxypropyl)amine (BHP). Metabolism studies indicated that BAP was readily converted in vivo to BHP and that BHP was also the major urinary metabolite.

Animals↗
PubMed1976

Common metabolites of N-nitroso-2,6-dimethylomorpholine and N-nitroso-bis(2-oxopropyl)amine in the Syrian hamster.

N-Nitroso-2,6-demethylmorpholine (NDMM) administered intraperitoneally to Syrian hamsters was metabolized to N-nitroso-bis(2-hydroxypropy)(2-oxopropyl)amine(HPOP) and N-nitroso-bis(2-hydroxpropyl)amine (BHP) which were identified in blood and urine. The potent pancreatic carcinogen N-nitroso-bis(2-oxoproply)amine was previously shown to form the same metabolites. Preliminary results indicate that NDMM also induces pancreatic and other tumors in Syrian hamsters, similar to those found following BHP treatment.

Aged↗
PubMed1976

Spontaneous tumors and common diseases in two colonies of Syrian hamsters. I. Incidence and sites.

Syrian hamsters from two colonies [Eppley colony (EC); Hannover colony (HC)] were examined for spontaneous neoplastic and noneoplastic diseases. Significant differences were found in tumor incidence (30%, EC' 42%, HC), occurrence of malignant neoplasms (15%, EC; 32%, HC), appearance of multiple primary tumors in different organs (42%, EC; 30%, HC), average survival rates of tumor-bearing animals, organ distribution and histologic types, and average survival rates of all animals. The frequencies of nonneoplastic diseases also varied between the two colonies. The findings indicated a need for precise histologic evaluation to generate information for comparative purposes regarding the use of hamsters in experimental pathology and carcinogenesis studies.

Animals↗
PubMed1976

Spontaneous tumors and common diseases in two colonies of Syrian hamsters. II. Respiratory tract and digestive system.

Spontaneous respiratory tract neoplasms in Syrian hamsters occurred in almost equal frequencies in two colonies: 3% in the Eppley Colony (EC) and 3.6% in the Hannover Colony (HC). Neoplasms were in the nasal cavity, trachea, and lungs, and most were benign; however, 2 adenocarcinomas of the nasal cavity (EC) and 1 adenocarcinoma of the larynx (HC) were found. The incidence of digestive tract tumors showed a more marked difference than that of the respiratory tract: 7% in the EC and 23% in the HC. Digestive tract tumors accounted for 15 and 41% of all tumors in the EC and HC, respectively. All EC digestive tract neoplasms were benign and occurred mostly in males; 19 (83%) were forestomach papillomas and the remaining 4 )17%) were liver hemangioendotheliomas (2) and pancreatic duct adenomas (2). In the HC, almost 50% of the digestive tract neoplasms were malignant and most frequent in females. These tumours include 19(42%) intestinal adenocarcinomas, 18(40%) liver neoplasms (hemangioendotheliomas, cholangiomas, cholangiocarcinomas), 5 (13%) forestomach papillomas, and 2 (4%) gallbladder polyps. The morphology of these neoplasms was reported.

Adenocarcinoma↗
PubMed1976

Spontaneous tumors and common diseases in two colonies of Syrian hamsters. III. Urogenital system and endocrine glands.

The frequency of spontaneously occuring neoplasms in the urogenital system and endocrine organs was examined in two Syrian hamster colonies [Eppley colony (EC); Hannover colony (HC)]. With the exception of a renal adenoma in an EC female, the urinary systems of animals in both colonies were free of neoplastic growths. A single epididymal adenoma of the male fenital system (EC) was found. However, incidences of female genital tract tumors were 10 (EC) and 3.5% (HC) and accounted for 34 and 11%, respectively, of all tumors in females. Among all genital tract tumors, 3 (EC) and 57% (HC) were ovarian, 14% (HC) were in the fallopian tubes, 81 (EC) AND 29% (HC) were uterine, and 16% (EC), vaginal. The overall incidence of endocrine organ tumors was similar in both colonies (EC, 22%; HC, 19%). The distribution of these tumors was as follows: pituitary gland; EC, 3%, HC, 0; thyroid gland: EC, 28%, HC, 31%; parathyroid gland: EC,11%, HC, 18%; adrenal cortex: EC, 42%, HC, 31%; adrenal medulla: EC, 7%, HC, 0; and endocrine pancreas: EC, 10%, HC, 31%. The morphology of these neoplasms is described and the incidence compared with those reported in other colonies.

Adrenal Gland Neoplasms↗
PubMed1976

Spontaneous tumors and common diseases in two colonies of Syrian hamsters. IV. Vascular and lymphatic systems and lesions of other sites.

Spontaneous tumors were found in the vascular and lymphatic systems upon systemic histologic examination of the cardiovascular, hematopoietic, and lymphatic tissues of Syrian hamsters from the Eppley (EC) and Hannover colonies (HC). The incidence of endothelial tumors (hemangioendotheliomas) was similar in both colonies and sexes. The hemangioendotheliomas generally originated in the liver and spleen. Malignant lymphomas developed in high incidences in both colonies; however, their morphology varied. Those in EC hamsters were of histiocytic and, to a lesser extent, plasmacytic types; in the HC lymphocytic and epithelioid cell types were also found. Among tumors of miscellaneous sites, Harderian gland adenomas occurred in almost equal frequencies in EC and HC hamsters, but predominated in males. Tumors of the bone and soft tissue were present only in EC hamsters, whereas skin neoplasms developed solely in HC hamsters.

Animals↗
PubMed1976

Metabolism of the pancreatic carcinogens N-nitroso-bis(2-oxopropyl)amine and N-nitroso-bis(2-hydroxypropyl)amine in the Syrian hamster.

Metabolisms of the potent pancreatic carcinogens N-nitroso-bis(2-oxopropyl)amine (BOP) and N-nitroso-bis(2-hydroxypropyl)amine (BHP) were studied in male Syrian hamsters. BHP and a new metabolite, N-nitroso-(2-hydroxypropyl)(2-oxopropyl)amine (HPOP), were detected in the urine of hamsters administered BOP and BHP. The rates of HPOP formation from BOP and BHP were determined by the measurement of blood and urine levels at various times after each compound was administered: HPOP was formed readily from BOP, but slowly from BHP. This may explain the different organotropic spectra and carcinogenic potencies of BOP and BHP.

Animals↗
PubMed1976

N-nitroso-bis(2-acetoxypropyl)amine as a further pancreatic carcinogen in Syrian golden hamsters.

N-Nitroso-bis(2-acetoxypropyl)amine, a possible beta metabolite of N-nitroso-di-n-propylamine, was shown to be a potent carcinogen in the Syrian golden hamster. After a single s.c. treatment, the pancreas was the most affected organ, followed by the liver, respiratory tract, and kidneys. However, repeated application resulted in a higher incidence of neoplasms of the respiratory tract than of the pancreas and kidneys. The effect of N-nitroso-bis(2-acetoxypropyl)amine on toxicity, target tissues, and carcinogenicity was similar to that of N-nitroso-bis(2-hydroxypropyl)amine. The assumption that these two compounds may have similar metabolic pathways was confirmed; N-nitroso-bis(2-acetoxypropyl)amine was readily deesterified to N-nitroso-bis(2-hydroxypropyl)amine in vivo and in vitro.

Animals↗
PubMed1976

Pancreatic neoplasms induced in Syrian golden hamsters. I. Scanning electron microscopic observations.

Pancreases from Syrian golden hamsters treated with N-nitrosobis(2-hydroxy-proply)amine for 10 to 25 weeks were examined under scanning electron microscopy (SEM). Findings indicate that the neoplasms originated from the ductal epithelium and developed progressively. Adenomas were lined by epithelium of differing cells types, ranging from a flat singly ciliated form to cuboidal-columnar types, or to mixed cell populations. The epithelial lining of the ductal carcinomas exhibited tubular and papillary cystic spaces, and cell surfaces were similar to the cuboidal and columnar epithelium of adenomas and of ductal epithelial hyperplasia. However, microvilli were dense and of varied lengths. The SEM observations correlated with patterns seen in routine histologic preparations.

Animals↗
PubMed1975

Pancreatic neoplasms in an animal model: morphological, biological, and comparative studies.

After a short latency (15 weeks), a 100% incidence of pancreatic neoplasms was induced in Syrian golden hamsters, following the administration of 2,2'-dihydroxy-di-n-propylnitrosamine (DHPN). Data extracted from reports of human pancreatic neoplasms were compared with findings relative to the induced neoplasms. The latter resembled human pancreatic tumors, in both biological and morphological aspects.

Adenocarcinoma↗
PubMed1975

Induction of pancreatic neoplasms by 2,2'-dioxopropyl-N-propylnitrosamine.

A high incidence of pancreatic duct adenomas and carcinomas were induced in Syrian golden hamsters as early as 13 weeks after chronic administration of 2,2'-dioxopropyl-n-propylnitrosamine (DOPN) at a 10 mg/kg dose. In contrast to another pancreatic carcinogen, 2,2'-dihydroxy-propyl-n-propyl-nitrosamine, DOPN induced no tumors of the upper respiratory tract or kidneys, and only a few neoplasms of the lungs and liver.

Adenocarcinoma↗
PubMed1975

Effect of beta-oxidized nitrosamines on syrian hamsters. III. 2,2'-Dihydroxydi-n-propylnitrosamine.

2, 2-Dihydroxy-di-n-propylnitrosamine (DHPN), an assumed metabolite of di-n-propylnitrosamine (DPN), injected subcutaneously once weekly for life, was carcinogenic in Syrian hamsters. The main target organs were the respiratory tract, pancreas, liver, and kidneys. In the respiratory system the most affected segments were the nasal cavities and the lungs. Adenomas and adenocarcinomas, mostly of ductal origin, were induced in the pancreas. Liver neoplasms were hemangloendotheliomas, angiosarcomas, hepatocellular adenomas, cholangiomas, and cholangiocarcinomas. Kidney neoplasms were adenomas and adenocarcinomas. The morphology of the induced neoplasms was described, as well as the effects of DHPN, compared to those another possible metabolite of DPN, 2-hydroxypropyl-n-propylnitrosamine (2-HPPN), which is formed in vivo with only 1 aliphatic chain degraded via theta-oxidation.

Adenocarcinoma↗