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Biomedical subjects

G Reznik

Publications and source records attributed to G Reznik.

At least 73 records · Page 4Linked to original sources
PubMed1977

Induction of pancreatic duct of carcinomas in the Syrian hamster with 2,6-dimethylnitrosomorpholine.

Pancreatic duct carcinomas were induced in Syrian hamsters by intragastric administration of 2,6-dimethylnitrosomorpholine. As early as 30 weeks after treatment began, tumors were macroscopically visible in the pancreas; the maximum incidence of such tumors reached 71% by the end of the experiment. They were ductal in origin, and some metastasized to the lung. They were identified histologically as adenomas and carcinomas and developed in different parts of the organ without demonstrating any preferred localization.

Animals↗
PubMed1977

Carcinogenicity of N-nitrosodiethylamine in hibernating and nonhibernating European hamsters.

Hibernating European hamsters reacted differently to sc injections of N-nitrosodiethylamine (DEN) than did European hamsters that were not hibernating. Hibernating animals tolerated higher dose levels but developed fewer neoplasms. In contrast, hibernating males had more pulmonary tumors than did the respective nonhibernators. However, the hibernating females of the low dosage group developed fewer lung tumors. The survival times were longer for the male hibernators than for the male nonhibernators. The organ specificity of DEN, as well as the morphology and histogenesis of the neoplasms, showed no differences between the hibernating and nonhibernating groups.

Adenocarcinoma↗
PubMed1977

Tumors of the heart and stomach induced in European hamsters by intravenous administration of N-methyl-N-nitrosourea.

One hundred twenty captured European hamsters (Cricetus cricetus L.) were inoculated iv with 1/5, 1/10, or 1/20 the median lethal dose of N-methyl-N-nitrosourea (MNU) once weekly for 18 weeks. MNU induced mainly sarcomas in the heart and squamous cell carcinomas and sarcomas in the stomach. The highest incidence of such tumors was demonstrated by the lowest-dosage group. They were more frequent in males than in females. The effect of MNU was also localized at the site of administration and resulted in squamous cell carcinomas of the oral cavity. The possible fibroblastic or neurogenic origin of the sarcomas was explored.

Animals↗
PubMed1977

[Animal experimental studies on the prevention of cleft palate and other malformations in the region of the head].

In fetuses of eight-week old female Swiss mice, teratogenic effects were produced by cyclophosphamid on different days of pregnancy. Frequently and combinations of malformation of a positive control group (30 mg/kg b.w. on the 11.5th day of pregnancy) were compared with "prophylaxis" groups. Pyrithioxin (Encephabol) significantly reduces the number of some malformations. The goal, i.e. to obtain normal fetuses without malformations, was not achieved, however. The best effect was obtained with 1/160 LD50 of Encephabol administered in four doses prior to Endoxan.

Abnormalities, Multiple↗
PubMed1976

Early X-ray detection of colonic and rectal tumours in European hamsters.

Three groups of European hamster (EH) (Cricetus cricetus L.) were treated subcutaneously every two weeks for life with 1/10 or 1/20 LD50 DMH, while two other groups served as controls. Twelve weeks after commencement of treatment, radiological examinations of the colon and rectum were begun. The double contrast method was used. In this way it was possible to detect the earliest neoplastic alteration to take place in the above sites. This occurred in the 26th treatment week and was diagnosed as an adenocarcinoma. The technique used is simple, as well as being suitable for large numbers of animals. In addition, it allows for early experimental analysis of results in respect to latency period, growth rate, incidence and location of tumours.

Animals↗
PubMed1976

Carcinogenic effects of different nitroso-compounds in Chinese hamsters. II. N-nitrosomorpholine and N-nitrosopiperidine.

A total of 320 Chinese hamsters (Cricetulus griseus) (CH) were subcutaneously (s.c.) treated with 1/5, 1/10, or 1/20 LD50 of N-nitrosomorpholine (NM) or N-nitrosopiperidine (NP). In the CH, NM and NP both produced up to a 100% rate of papillomas of the cheek pouch, tongue, pharynx, esophagus and forestomach. Occasionally squamous cell carcinomas also developed in these organs. A high rate of hepatomas was realized by NP.

Animals↗
PubMed1976

Carcinogenic effects of different nitroso-compounds in chinese hamsters: N-dibutylnitrosamine and N-nitrosomethylurea.

Three hundred and twenty Chinese hamsters (Cricetulus griseus) (CH) were subcutaneously (s.c.) treated with 1/5, 1/10 or 1/20 the mean lethal dose (LD50) of N-dibutylnitrosamine (DBN) or N-nitrosomethylurea (NMU). In several respects these two substances produced the same organotropy in the CH as in the Syrian golden (SGH) and European hamsters (EH). DBN prolonged lung tumours and neoplasms of the injection site. NMU induced tumours of the injection site only.

Animals↗
PubMed1976

Induction of renal pelvic tumours in Sprague-Dawley rats by di-isopropanolnitrosamine.

Transitional cell papillomas and carcinomas of the renal pelvis were observed in Sprague-Dawley rats after subcutaneous (s.c.) treatment with di-isopropranolnitrosamine (DIPN). These tumours occurred unilaterally and appeared as early as 24 weeks after the commencement of treatment. The tumours frequently filled the entire renal pelvis and compressed the kidney parenchyma. The malignant neoplasms demonstrated infiltrative growth into the adjacent medullary parenchyma.

Animals↗
PubMed1976

Carcinogenic effects of different nitroso-compounds in Chinese hamsters. I. Dimethylnitrosamine and N-diethylnitrosamine.

Three hundred and twenty Chinese hamsters (Cricetulus griseus) (CH) were treated (s.c.) with 1/5, 1/10 or 1/20 LD50 of dimethylnitrosamine (DMN) or N-diethylnitrosamine (DEN). These substances, in several respects, showed a different organotropy in this species than in both the Syrian golden (SGH) and the European hamster (EH). In CH, DEN produced up to 100% squamous cell papillomata and occasionally also carcinomata of the cheek pouch, tongue, pharynix, oesophagus and forestomach. With DEN a high rate of hepatomata was simultaneously realized. DMN induced a considerable quantity of liver tumours, the highest incidence being demonstrated in the lowest dosage group.

Animals↗
PubMed1976

Intrasplenic tumor formation in the syrian hamster (Mesocricetus auratus) after tracheal implants and treatment with diethylnitrosamine.

In two simultaneous experiments (A and B), tracheal tissue from 25 young Syrian hamsters was implanted in their mothers' spleens. In A, after tracheas from 3-week-old untreated donor offspring were implanted into their mothers, the mothers received 18 mg diethylnitrosamine (DEN)/kg body weight, sc, twice weekly for 20 weeks. Thereafter, the implants were removed and transferred to the spleens of other untreated offspring that were then similarly treated with DEN for 20 weeks. In B, the procedure was similar except that the donor offspring were pretreated with DEN for 20 weeks, beginning at the age of 8 weeks. The average treatment time for the implants in experiment A was 65 weeks; in B, 44 weeks. In A, only four implants demonstrated a papilloma or a papillary polyp. In B, such neoplasms developed after a much shorter treatment time, and in three cases, squamous cell carcinomas with invasive growth in to the splenic pulp were formed.

Animals↗
PubMed1976

Experimentally induced cleft palates and prophylactic studies in Swiss mice.

In order to examine its prophylactic effect, Actihaemyl, (Solcoseryl) was administered to pregnant Swiss mice at various intervals before and after i.p. treatment with 30 mg/kg b.w. Endoxan; the optimal time for administration of the latter was found to be the 11.5th day of pregnancy. A sifnificant reduction (P larger than or equal to 0.01) of the rate of experimentally induced cleft malformations, as well as other types of abnormalities of the head area, was demonstrated in comparison to the control groups. These results were even more pronounced when the mother animals were treated in the following manner: 1/10 LD50(19.7 ml/kg b.w.) of Actihaemyl 1 day, 10 and 5 min before Endoxan, followed by similar doses 5, 10 min and 2 days afterwards. Three prophylactic groups, from a total of 20, demonstrated a significant (p larger than or equal to 0.01) reduction in the cleft palate rate. Three additional groups showed reductions of more than 60% of exophthalmuses and over 25% of encephaloceles.

Abnormalities, Drug-Induced↗
PubMed1976

Gingiva and periodontium in lepromatous leprosy. A clinical, radiological, and microscopical study.

Thirty patients with lepromatous leprosy of long duration were examined for gingival and periodontal changes. All patients presented with chronic gingivitis and periodontitis of an unspecific type. Etiologic factors affecting the development of gingival and periodontal changes in this disease are: lack of oral hygiene with severe plaque and calculus formation due to the inability of the patients to perform oral hygiene, mouth breathing, specific granulomatous infiltrations, and a possible specific drug action. Specific changes in form of 'facies leprosa' are not pathognomonic of lepromatous leprosy but may be found in 20% of the cases among Thai and Chinese patients. Occurrence and pathogenesis of 'facies leprosa' is described.

Adult↗
PubMed1976

Investigations on the carcinogenic burden by air pollution in man. XIV. Effects of automobile exhaust condensate on the Syrian golden hamster lung.

Syrian golden hamsters were intratracheally instilled with 5 or 2.5 mg/animal of automobile exhaust condensate at two weekly intervals. Moribund animals were fixed by intravascular perfusion. Samples of lobar and segmental bronchi, as well as of peripheral lung tissue, were taken for electron microscopical examination. In addition, all organs were examined histologically. After a survival time of 30 to 60 weeks all animals developed multiple pulmonary adenomas, thus indicating a marked carcinogenic effect of automobile exhaust condensate.

Adenoma↗