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Biomedical subjects

G Reznik

Publications and source records attributed to G Reznik.

At least 91 records · Page 5Linked to original sources
PubMed1975

Comparison of four different methods for the recovery of dotriacontane-16,17-14C from small animal respiratory tissue.

The efficiency and accuracy of four different methods of tissue preparation for the recovery of dotriacontane-16,17-14C (DOT-16,17-14C) from rat respiratory tissue were compared by means of liquid scintillation counting. A DOT-16,17-14C standard solution was placed on the respiratory epithelium of the nasal apex, larynx, trachea and main bronchi. Combustion of the lyophilized organs in a Packard sample oxidizer revealed the highest recovery and accuracy (93--100%), sample oxidizing by combustion without lyophilization the lowest recovery and accuracy (73--92%). Tissue solubilization by the commercially available tissue solubilizer TS-1 revealed a better recovery and accuracy (89--95%) than tissue maceration by boiling in methanolic KOH and toluene extraction (74--91%). Depending on the laboratory equipment, lyophilization or tissue solubilization is preferred; maceration and toluene extraction as well as combustion without freeze-drying are disregarded for further investigations because of the cumbersome procedure as well as the low recovery and accuracy, respectively.

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PubMed1975

Diagnosis of experimentally induced bronchogenic tumours in the european hamster with bronchographs.

Four groups of European hamsters were treated subcutaneously once weekly for life with 1/20 or 1/40 the diethylnitrosamine LD 50. Three animals from each treatment group and the two control groups were examined every three weeks by means of bronchographic technique. In four of the animals the bronchograms showed early neoplastic alterations of the bronchial system. The results demonstrate that bronchography is a suitable method for the diagnosis of bronchogenic tumours in the European hamster and that it also allows for the detection of displacing neoplasms of non-bronchogenic origin in the region of the tracheal bifurcation.

Animals↗
PubMed1975

Inhalation experiments with 14C-labelled cigarette smoke. I. Determination of the effectiveness of two different smoking systems with labelled cigarettes.

Two different smoking systems were tested by exposing Syrian golden hamsters to the smoke of cigarettes labelled with (14C)dotriacontane-16, 17 (DOT). In 3 experiments, the activity of mainstream and sidestream Total Oarticulate Matter (TPM) and of butts and ash was determined. Comparing the results, the system involving individual exposure was shown to provide the animals with higher amounts of mainstream TPM than the system using simultaneous exposure of numerous animals.

Animals↗
PubMed1975

Inhalation experiments with 14C-labelled cigarette smoke. II. The distribution of cigarette smoke particles in the hamster respiratory tract after exposure in two different smoking systems.

Male and female Syrian golden hamsters were exposed to the smoke of [14C]dotriacontane-16,17 ([14C]DOT)-labelled cigarettes in 2 different exposure systems. These 2 systems differed in terms of the smoke concentration drawn into the exposure chamber. To compare the effectiveness of the exposure systems, the inhaled dose of 14C-labelled cigarette smoke was determined in the different parts of the hamster respiratory tract by liquid scintillation counting. About 6 times more smoke particles were deposited in the respiratory tract after exposure to high smoke concentration with intermittent puffs of fresh air (closed system) than after exposure to smoke diluted with air (open system). About 80% of the diluted smoke reached the bronchi and lung compared to approximately 60% of the concentrated smoke. The remainder of the dose was trapped in the upper respiratory tract, mainly by the nose and larynx. Additionally, in the open system the total dose of inhaled smoke was dependent upon the position in the exposure chamber. The results are discussed with respect to the use of the exposure systems for chronic cigarette smoke inhalation studies in experimental respiratory tract carcinogenesis.

Animals↗
PubMed1975

The carcinogenic effect of dimethylnitrosamine on the Chinese hamster (Cricetulus griseus).

Three groups of Chinese hamsters (20 males, 20 females/group) received weekly subcutaneous injections for life of dimethylnitrosamine (DMN) at dose levels 0.20, 0.10 and 0.05 of the LD50. Eighty-two to 100% of the animals developed tumors of vascular origin. The neoplasms were primarily hepatic hemangioendotheliomas and their incidence was unrelated to dose or sex. Although animals in the low dose group received a total dose which was one-third that of the highest dose group, their survival times were only slightly longer.

Animals↗
PubMed1975

Transplacental effects of diethylnitrosamine in Syrian hamsters as related to different days of administration during pregnancy.

Female Syrian hamsters were given a single sc dose of 45 mg diethylnitrosamine (DEN)/kg body weight on 1 of the 15 days of pregnancy. In the offspring of females treated on 1 of the first 11 days of pregnancy, no respiratory tract tumors were found. The offspring of mothers given DEN on 1 of the last 4 days (12-15) of pregnancy developed respiratory tract neoplasms at a rate of up to 95%. A lower incidence of tumors in other organs seemed independent of the day of DEN treatment.

Animals↗
PubMed1975

X-ray enlargement modified for use in experimental animal science.

The primary enlarged x-ray image is produced by a reduction of the focal-film-distance to 80 cm at a given focal size of 0-15 mm. The advantages of this technique as compared to conventional x-ray methods are exemplified with x-ray images from the shoulder joint of a European hamster, a pseudoarthrosis in the foreleg of a beagle, and a renovasography of a rat. The principles of the technique and its significance for investigations using small laboratory animals are discussed.

Animals↗
PubMed1975

Carcinogenic effects of Di-n-propylnitrosamine, beta-hydroxypropyl-n-propylnitrosamine, and methyl-n-propylnitrosamine on Sprague-Dawlay rats.

The carcinogenic effects of di-n-propylnitrosamine and its two related compounds, beta-hydroxypropyl-n-propylnitrosamine (HPPN) and methyl-n-propylnitrosamine (MPN), were tested in rats and compared. All three substances induced neoplasms in the nasal and paranasal cavities, esophagus, and liver. MPN treatment caused the highest tumor incidence in the esophagus, whereas HPPN induced the most hepatic tumors.

Animals↗
PubMed1975

Comparative studies of blood from hibernating and nonhibernating European hamsters (Cricetus cricetus L).

The blood of 6 male and 6 female European hamsters (Cricetus cricetus L) was examined in summer, in winter before hibernation, and 1 da after awaking from hibernation. Blood was drawn from a sublingual vein under ether anesthesia in nonhibernating animals. No influence of hibernation upon the number of erythrocytes and the differentials was found, whereas the number of thrombocytes and leukocytes were reduced to a minimum. From the unchanged numbers of thrombocytes and leukocytes in nonhibernating animals during winter, the influence on the blood of a seasonal cycle independent of hiberation was excluded.

Animals↗
PubMed1975

Effects of cigarette smoke on the bronchial epithelium of Syrian hamsters: ultrastructural studies.

The effects of two types of research cigarettes, which differed in their total smoke delivery and condensate, on the bronchial epithelium of Syrian hamsters were examined electronmicroscopically. The animals were exposed once a day for 5 days each week for 1 year to the total smoke of the cigarettes. Two groups and a control group were killed 1 day after the last exposure, and one group 12 months after the last exposure. The bronchial epithelia of all smoke-exposed animals were hyperplastic, and their ultrastructure showed invaginations, tilt of nuclear axes, an increase in the number and size of lysosomes and multivesiculated bodies, and increased numbers of enlarged intramitochondrial granules. Squamous metaplasia, rarely found, was present at the stage of filamentous bundle formation. The induced alterations were independent of the type of cigarette used. One year after smoking was terminated, the alterations had neither reversed nor advanced, as compared to those occurring 1 day after the last smoke exposure.

Animals↗
PubMed1975

Comparative studies concerning the suitability of European hamsters and Syrian golden hamsters for investigations on smoke exposure.

The suitability of the European hamster and the Syrian golden hamster for experiments with tobacco smoke has been tested under various conditions by exposure of the animals to total smoke and the gas vapour phase of two cigarettes. Respiration rate, tidal volume and CO-Hb concentrations were measured before and after the exposures. The results demonstrate that the European hamster tolerates smoke inhalation under all conditions studied better than the Syrian golden hamster. In addition, the haemoglobin of the European hamster showed a markedly lower affinity for carbon monoxide than that of the Syrian golden hamster. In the European hamster, therefore, the danger of CO poisoning after repeated exposures to tobacco is much smaller than in the Syrian golden hamster. The European hamster can be regarded as a more suitable model for investigations with highly concentrated and prolonged smoke inhalations.

Animals↗
PubMed1974

Radiological detection and sequential observation of experimentally induced bladder tumours in the European hamster.

FOUR GROUPS OF EUROPEAN HAMSTERS (STRAIN MHH: EPH) were treated subcutaneously once weekly for life with 1/20 or 1/40 the LD(50) of DBN while another 2 groups served as controls. Three animals of each group were x-rayed every 2 weeks after i.v. injection of the contrast agent Urographin. By means of cystograms tumours of the urinary bladder were detected between the 20th and 26th weeks after beginning treatment when they had reached a diameter of 1-2 mm; their development was subsequently observed by periodical x-ray examinations. The technique described is simple and provides a valuable means for obtaining additional in vivo information concerning latency period, growth rate and identity of experimentally induced primary urinary bladder tumours in the European hamster.

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