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Biomedical subjects

G Reznik

Publications and source records attributed to G Reznik.

At least 19 recordsLinked to original sources
PubMed1992

Percutaneous endoscopic implantation of Automatic Implantable Cardioverter/Defibrillator (AICD): an animal study of a new nonthoracotomy technique.

The Automatic Implantable Cardioverter/Defibrillator (AICD) prevents death due to malignant ventricular arrhythmias but requires thoracotomy for the implantation of the preferred two-patch lead system. The purpose of this study was to develop and test a new percutaneous endoscopic method of the AICD lead implantation without the need for open chest surgery. A high resolution video endoscopy system and currently available endoscopic instrumentation were used to develop pleural-pericardial dissection technique in 7 pigs and to endoscopically implant custom-made AICD patches in 20 pigs. An examining 10 mm rigid endoscope inserted in the 6th intercostal space in the anterior axillary line provided direct visual control for endoscopic dissection of the parietal pleura from the pericardium, delivery, and implantation of the AICD patches. This was successfully carried out through two trocars (10 and 11 mm) inserted into the pleural-pericardial space via the subxyphoid approach in 18 of 20 pigs. Effective patch positioning was confirmed by attaining a defibrillation threshold of 20J or less in 13 pigs. Of those, three required lead polarity reversal, and three others required lead repositioning to lower defibrillation thresholds to 20J or less. In three pigs, defibrillation thresholds of 30J or higher were required. Defibrillation was unsuccessful in two pigs due to patch malfunction. The authors conclude that percutaneous endoscopy is a feasible method of AICD lead implantation.

Animals↗
PubMed1979

The influence of chemotherapy on the distribution of 57Co-bleomycin in chemically induced squamous cell carcinoma of mouse skin.

Organ distribution and tumor uptake of 57Co-bleomycin (BLM) were examined in NMRI mice without tumor and with chemically (DMBA-) induced squamous cell carcinoma. In these tumors high accumulation of 57Co-BLM was recorded shortly after injection of 57Co-BLM and low uptake 24--48 h after application. Two groups of tumor-bearing mice received unlabeled bleomycin as a cytostatic in two different doses. Uptake of 57Co-bleomycin was reduced. The study suggests that in patients currently or previously under chemotherapy, 57Co-bleomycin tumor scintigraphy may lead to false negative results.

Animals↗
PubMed1979

Renal carcinogenic and nephrotoxic effects of the flame retardant tris(2,3-dibromopropyl) phosphate in F344 rats and (C57BL/6N X C3H/HeN)F1 mice.

Tris(2,3-dibromopropyl) phosphate (TBP) was administered in the feed at one of two concentrations to groups of 55 male and 55 female inbred F344 rats and to 50 male and 50 female (C57BL/6N X C3H/HeN)F1 mice. The high and low dietary concentrations of TBP administered orally were 100 and 50 ppm for the rats, respectively, and 1,000 and 500 ppm for the mice, respectively. For each rodent type, 55 animals of each sex were used as contols. In both rodent types, renal epithelial tumors developed at incidences that were significant for male and female rats and mice that received the doses. These tumors included renal tubular cell adenomas and carcinomas that developed from the proximal convoluted tubular epithelium. Among female mice and rats, hyperplasia and/or dysplasia of the proximal convoluted tubular epithelium with or without cystic dilatation of the tubules and increase in the size of cell nuclei were dose dependent and recognized as preneoplastic and/or toxic lesions. The comparative histogenesis of renal tubular neoplasms was discussed.

Adenocarcinoma↗
PubMed1979

Bronchoscopy in the European hamster (Cricetus cricetus).

A pediatric bronchoscope was modified for use in the European hamster (Cricetus cricetus) and has been used successfully to obtain biopsy specimens from these animals. Biopsy specimens were obtained by means of small forceps with visual control given by the modified bronchoscope.

Animals↗
PubMed1979

Teratogenic effect of cyclophosphamide and the preventive effects of pyrithinoldehydrochloride monohydrate.

Teratogenic effects were induced in outbred Swiss mice by treatment of 8-week-old pregnant females with one of five different doses (5, 10, 20, 30, 40 mg/kg b.w.) of cyclophosphamide. Because the 11.5th day of pregnancy was the most effective day to induce malformations in mice, animals treated on this day were used for prophylactic studies. A preliminary study had shown that 30 mg/kg b.w. cyclophosphamide was the ideal dose to produce 100% malformations on the 11.5th day of pregnancy. From day 7.5 to 9.5 all fetuses were resorbed with this dosage. Most malformations were induced with 20, 30 or 40 mg/kg b.w., whereas 5 and 10 mg/kg b.w. caused no alterations of the fetuses. The frequency distributions of the various induced malformations and combined malformations of a positive control group (30 mg/kg b.w. of cyclophosphamide on the 11.5th day of pregnancy) were compared to those found in groups receiving different doses of the prophylactic. This substance reduced significantly the rate of malformations; 1/160 LD50 pyrithinoldehydrochloride monohydrate administered 4 times prior to cyclophosphamide treatment was the most effective. However, a complete prevention of teratogenic effects could not be accomplished.

Abnormalities, Drug-Induced↗
PubMed1979

[Influence of radiotherapy upon tumor accumulation and organ distribution of 57Co-bleomycin in mice with chemically induced squamous cell carcinoma (author's transl)].

Squamous cell carcinoma was induced in male 6 to 8-week old NMRI-mice by application of 9,10-dimethyl-1,2-benzanthracene on the skin. 15 weeks later macroscopically visible skin tumors are developed. Then organ distribution and tumor accumulation of 57Co-Bleomycin (spec. activity 1 mCi/3.3 mg) were studied 1 to 48 hours after injection. In squamous cell carcinoma a high uptake of this tumor-seeking agent can be demonstrated (n = 46). After radiotherapy (100 kV; 1.7 mm Al-filter; 18.8 Gy) (n = 26), however, a significantly reduced uptake of 57Co-Bleomycin in tumor tissue is observed. Possible consequences from these animal studies for tumor scintigraphy with this radiopharmaceutical in man are discussed.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

Investigations on the carcinogenic burden by air pollution in man. Intratracheal instillation studies with benzo(a)pyrene in bovine serum albumin in Syrian hamsters.

The chronic effect of benzo(a)pyrene (B(a)P) administered intratracheally in bovine serum albumin was studied in Syrian golden hamsters. Dose levels of 0.1 mg, 0.33 mg and 1.0 mg of B(a)P induced papillomas and carcinomas of the trachea, stem bronchi and bronchioles. In addition to such tumours, the mucosa of the respiratory tract revealed a variety of atypical epithelial alterations. Although survival time exhibited a dose-dependency, tumour incidence did not. The incidence of respiratory tract tumours was higher in female hamsters than in males. The results of these investigations are statistically evaluated.

Air Pollutants↗
PubMed1978

Carcinogenic effect of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in European hamsters.

Laboratory-bred European hamsters received intragastric administrations of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) once weekly for 20 weeks. The animals showed mainly squamous cell papillomas and carcinomas of the fore-stomach. The tumour incidence was higher in males (80%) than in females (30%). The average tumour latency was comparatively short (25 weeks).

Animals↗
PubMed1978

Carcinogenic effect of N-nitroso-2,6-dimethylmorpholine in Syrian golden hamsters.

N-Nitroso-2,6-dimethylmorpholine was intragastrically administered to Syrian golden hamsters at four different dose levels [74 mg/kg body wt = 1/5 median lethal dose (LD50); 37 mg/kg body wt = 1/10 LD50; 18 mg/kg body wt = 1/20 LD50; and 9 mg/kg body wt = 1/40 LD50]. Up to a 71% rate of pancreatic tumors was induced. These tumors were adenomas or adenocarcinomas of ductal origin. In addition, neoplasms developed in different percentages in the nasal cavities, larynx, trachea, lungs, liver, gallbladder, kidneys, and forestomach. The number of tumors induced was not significantly dose-dependent.

Animals↗
PubMed1978

Carcinogenicity of subcutaneously injected N-nitrosoheptamethyleneimine in European hamsters.

Male and female European hamsters (45 of each sex) recieved sc injections once weekly for life of N-nitrosoheptamethyleneimine (NHMI) at one-fifth the median lethal dose (LD50) (females: 44 mg/kg body wt; males: 66 mg/kg body wt), one-tenth the LD50 (females: 22 mg/kg body wt; males: 33 mg/kg body wt), or one-twentieth the LD50 (females: 11 mg/kg body wt; males: 16.5 mg/kg body wt). Survival times for both males and females were dependent on the dose of NHMI. Pulmonary neoplasms were induced in almost all the treated animals. They were histologically diagnosed as adenocarcinomas, squamous cell carcinomas, and mixed cell carcinomas. In addition, nasal cavity tumors developed in all hamsters of all treatment groups; these were papillomas, squamous cell carcinomas, and a few adenocarcinomas. Only 1 tumor of the larynx and 1 tumor of the trachea were observed. Several papillomas and a few carcinomas were also detected in the forestomach. The results were discussed with reference to previous findings in rats and Syrian golden hamsters.

Adenocarcinoma↗
PubMed1977

The carcinogenic effect of beta-oxidized dipropylnitrosamine in mice. I. Dipropylnitrosamine and methyl-propylnitrosamine.

Di-n-propylnitrosamine (DPN) and methyl-n-propylnitrosamine (MPN) induced mainly respiratory tract neoplasms in female NMRI mice after subcutaneous administration. The majority of tumors occurred in the nasal cavities, although significant incidences were also found in the larynx, trachea and stem bronchi. Treatment with both substances additionally resulted in vascular neoplasms of the liver, while DPN only caused tumors in the pharynx, esophagus and forestomach.

Animals↗
PubMed1977

[Experimental carcinogenesis in the respiratory tract using the European field hamster (Cricetus cricetus L.) as a model].

Subcutaneous treatment of European hamsters with aliphatic (diethyl-, diisopropanol-,dibutylnitrosamine) and cyclic nitroso compounds (nitrosopiperidine, morpholine, and heptamethyleneimine) led to the development of respiratory tract tumors. Most of the neoplasms were seen in the nasal cavity and lungs, although tumors were also found in the larynx and trachea. Histologically, the tumors were diagnosed as papillary polyps, papillomas, adenomas, adenocarcinomas, squamous cell carcinomas and mixed carcinomas. The length and weight of this species permit the performance of routine diagnostic methods such as radiography, bronchography and bronchoscopy. All such methods help towards a particularly early diagnosis of benign and malignant lesions.

Adenocarcinoma↗
PubMed1977

Pathological alterations in Syrian golden hamster lungs after passive exposure to cigarette smoke.

The effects of 2 types of research cigarettes, differing in their total smoke delivery and condensate, were examined as to their histopathological effects of Syrian golden hamster lungs. The animals were passively exposed to the total smoke of the cigarettes once a day, 5 days/week for 1 year. Experimental and control animals were killed one day after termination of exposure. Varying effects on the macrophages of pulmonary alveolar tissue were observed. Infiltration of lung tissue by "Brown cells" was a common pathological alteration. Qualitative and quantitative differences existed between the two cigarette groups with respect to the occurrence of such "Brown cell" clumps. The response of the lung tissue to smoke exposure would appear to be dependent upon the amount of mainstream total particulate matter (TPM), the amount of condensate, the time exposed and the number of cigarettes.

Animals↗