Microangiography is a very effective method in evaluating morphological changes of small vessels not onlybecause it shows subtle changes in microvasculature but also shows whole length of the vessels. Reccently many experimental studies on microagniography of normal and injured tissues are reported, but there's no report on microangiography of artificially induced cancer tissue. Authors artificially induced breast carinoma in rats withintravenous infusion of carcinogenic substance, N-methyl-N-Nitrosourea, and microangiography was done to evaluate vascularity and morphological changes of vessels of the cancer tissue. The results are as follows; 1.Distribtution of the tumor vessels showed tendency to form bolules. 2. Overall tumor vascularity was slightly hypervascular. 3. Variable sized, parallell arraged, tumor vessels surrounded the boundary of the lobules whilemore small vessels invaginated to the center of lobules in tortuous or straight fashion. 4. In overall, peripherayof the lobule was more vascular than center. 5. There was no evidence of cental tumor necrosis, and findings of extravasation of dye or venous lake formation were minimal. 6. Pathologically, the tumor tissue was well differentiated adenocarcinoma with tendency of lobule formation.
Adenocarcinoma ; Animals ; Breast Neoplasms ; Breast ; Lakes ; Methods ; Methylnitrosourea ; Microvessels ; Necrosis ; Rats

PURPOSE: To evaluate the early ERG (electroretinogram) changes in N-methyl-N-nitrosourea (MNU)-induced retinal degeneration in rats. METHODS: Thirty-six 6-week-old male rats were injected intraperitoneally with 60mg/kg MNU and divided into 6 groups. Histology and ERG were recorded for the rats of each group before treatment and at 3, 6, 12, 18, and 24 hours after MNU injection. Promptly after the ERG recording, rats were sacrificed and the eyeballs prepared for histologic sectioning. The Tdt-mediated dUTP-digoxigenin nick end labeling (TUNEL) method was used to detect photoreceptor cell death. RESULTS: The first decreases of ERG responses were noticed maximally at 3 hours after the treatment. Thereafter, the amplitude of the responses was partially recovered at 12 hours post-treatment. The second decrease of ERG amplitudes was observed in the 18-hour recordings, and those changes progressed to 24 hours after the treatment. In the histologic findings, TUNEL (+) cells in the Outer Nuclear Layer (ONL) were not detected at 3 hours after MNU injection, but were initially noticed at 6 hours post-injection. CONCLUSIONS: The first decreases of ERG amplitudes proceeded the appearance of TUNEL (+) cells in ONL, and these electrophysiological changes seemed to not be related to photoreceptor cell death. We propose that electrophysiological changes observed might be related to the MNU-induced activity enhancement of guanylate cyclase in the phototransduction pathway. We also show that photoreceptor cell death in the MNU-induced retinal degeneration model occurs at 6 hours after the treatment, which is earlier than the results of previous reports.
Animals ; Guanylate Cyclase ; Humans ; In Situ Nick-End Labeling ; Light Signal Transduction ; Male ; Methylnitrosourea ; Photoreceptor Cells ; Rats* ; Retinal Degeneration* ; Retinaldehyde*

OBJECTIVE: This study aimed to determine the effects of garlic (Allium sativum) on N-Methyl-N-Nitrosourea induced transitional carcinoma in Wistar rats.

METHODOLOGY: Transitional cell carcinoma was induced in thirty male, age-matched Wistar rats (45-50 days old) through intravesical instillation of 0.1mL of N-Methyl-N-Nitrosourea. They were divided into five treatment groups (0.1 mL of NSS; 0.1 mL of Mitomycin C; 0.1 mL of aqueous garlic extract in 10 mg/kg, 20 mg/kg, and 40 mg/kg given daily for the duration of the study); with one rat sacrificed every week (starting two weeks from tumor induction) until all rats were sacrificed after one month. The urinary bladders of the rats were subjected to histopathologic examination by a single veterinary pathologist. One-way ANOVA was used to compare mitotic index, papillomatous growth and vascularization of the specimens at Day 14 (baseline), 21 and 28. A P-value of less than 0.05 was used to detect significant difference.

RESULTS: Statistical analysis comparing mitotic index, papillomatous growth and vascularization showed no significant difference in the indices between the five treatment groups. It can be seen through that the P-value (0.144) for papillomatous growth was the smallest, which may indicate a trend towards a decrease in tumor growth at Day 28 for Mitomycin C and Garlic 40 mg/kg.

CONCLUSIONS: This preliminary study showed a favorable trend towards decreased papillomatous growth in the MNU induced rat bladder carcinoma treated with aqueous extract of Garlic (Allium sativum) at a higher dose and longer duration of time.

Animal ; Male ; Carcinoma, Transitional Cell ; Neoplasms ; Carcinoma ; Garlic ; Plants ; Urinary Bladder ; Rats, Wistar ; rats ; Plant Extracts ; Methylnitrosourea ; Nitrosourea Compounds

Since genetic models for retinal degeneration (RD) in animals larger than rodents have not been firmly established to date, we sought in the present study to develop a new rabbit model of drug-induced RD. First, intravitreal injection of N-methyl-N-nitrosourea (MNU) without vitrectomy in rabbits was performed with different doses. One month after injection, morphological changes in the retinas were identified with ultra-wide-field color fundus photography (FP) and fundus autofluorescence (AF) imaging as well as spectral-domain optical coherence tomography (OCT). Notably, the degree of RD was not consistently correlated with MNU dose. Then, to check the effects of vitrectomy on MNU-induced RD, the intravitreal injection of MNU after vitrectomy in rabbits was also performed with different doses. In OCT, while there were no significant changes in the retinas for injections up to 0.1 mg (i.e., sham, 0.05 mg, and 0.1 mg), outer retinal atrophy and retinal atrophy of the whole layer were observed with MNU injections of 0.3 mg and 0.5 mg, respectively. With this outcome, 0.2 mg MNU was chosen to be injected into rabbit eyes (n=10) at two weeks after vitrectomy for further study. Six weeks after injection, morphological identification with FP, AF, OCT, and histology clearly showed localized outer RD - clearly bordered non-degenerated and degenerated outer retinal area - in all rabbits. We suggest our post-vitrectomy MNU-induced RD rabbit model could be used as an interim animal model for visual prosthetics before the transition to larger animal models.
Animals ; Atrophy ; Intravitreal Injections ; Methylnitrosourea ; Models, Animal ; Models, Genetic ; Photography ; Rabbits ; Retina ; Retinal Degeneration ; Retinaldehyde ; Rodentia ; Tomography, Optical Coherence ; Vitrectomy

A wide-spectrum initiation model was investigated in mice. Sequential treatments with diethylnitrosamine, urethane and N-methylnitrosourea, with or without a promoter, phenobarbital, resulted in tumor formation in the lungs in 85-90% of animals, but did not produce any tumorous lesions in other organs. The lung tumors were adenomas and the mean number of adenomas was 2.2-2.6 per mouse. Phenobarbital combination had no additive effect on lung tumor incidence and multiplicity. Splenic NK cell activity showed inconsistent increment in the carcinogen plus phenobarbital-treated group during the experiment (P less than 0.05).
*Adenoma/chemically induced/immunology ; Animals ; Diethylnitrosamine/pharmacology ; Female ; *Killer Cells, Natural/drug effects ; *Lung Neoplasms/chemically induced/immunology ; Methylnitrosourea/pharmacology ; Mice ; Phenobarbital/pharmacology ; Random Allocation ; Urethane/pharmacology

The retinal degeneration (RD) is a general cause of blindness. To study its pathophysiology and evaluate the effects of new therapeutic agents before clinical trials, it is essential to establish reliable and stable animal models. This study evaluated a RD animal model in which blindness was induced by N-methyl-N-nitrosourea (MNU), a potent retinotoxin leading to apoptosis of photoreceptors. MNU was applied to the Sprague-Dawley rats by a single intraperitoneal injection in different doses (40, 50, and 60 mg/kg). The retinal functions were examined at 1 week after MNU injection by electroretinogram (ERG). Afterwards, each retina was examined by hematoxylin and eosin stain and immunohistochemistry with anti-glial fibrillary acidic protein antibody. Upon MNU injection of 40, 50 and 60 mg/kg, the ERG amplitude of a-waves showed significant reductions of 7, 26, and 44%, respectively, when compared to that of normal a-waves. The b-wave amplitudes were about 89, 65, and 58% of normal b-waves in the response to scotopic light stimulus. At 1 week, 2 weeks, and 4 weeks after MNU injection (50 mg/kg), all scotopic ERG components decreased progressively. In addition, degeneration of retinal neurons was observed in a time- and dose-dependent manner after MNU injection. Taken together, functional reduction following RD induced by MNU correlates with morphological changes. Thus, this RD rat model may be a useful model to study its pathophysiology and to evaluate the effects of new therapeutic agents before clinical trials.
Animals ; Apoptosis ; Blindness ; Electroretinography ; Eosine Yellowish-(YS) ; Hematoxylin ; Immunohistochemistry ; Injections, Intraperitoneal ; Light ; Methylnitrosourea ; Models, Animal ; Rats ; Rats, Sprague-Dawley ; Retina ; Retinal Degeneration ; Retinal Neurons ; Retinaldehyde

The 8-hydroxydeoxyguanosine (8-OH-dG), DNA adduct produced by oxygen radical-induced hydroxylation of C-8 position of guanine residue is accepted as to cause mutation and associate with carcinogenesis, and there are many carcinogens those produce oxygen radicals. Although many carcinogens have been accepted to induce bladder tumor, there is little known about the mechanism of carcinogenesis by these carcinogens. Following administration of bladder carcinogen, N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN), 4-Aminobiphenyl (4-ABP), 2-naphthylamine (2-NA) and N-methyl-N-nitrosourea (MNU) to human normal bladder epithelial cell, the results were obtained.1. Following administration of aromatic amine carcinogen, BBN, 4-ABP and 2-NA, the content of 8-OH-dG was increased to about 30-35 % although some variation of time existed according to the kinds of carcinogens. 2. Following administration of MNU, the content of 8-OH-dG was increased to about less than 3 % over all times. 3. Following administration of H2O2 that produce oxygen radicals without metabolism, the content of 8-OH-dG was increased to about 37 %. From this result, it can be supposed that the in crease of 8-OH-dG by carcinogens is induced by oxygen radical.The results obtained suggest that there are some enzymes in bladder epithelium that are related to metabolism of aromatic amine carcinogens and modification of DNA in bladder epithelial cell by the oxygen radicals, that is Formation of 8-OH-dG, is induced in carcinogenesis of bladder tumor byaromatic amine carcinogens.
2-Naphthylamine ; Carcinogenesis ; Carcinogens* ; DNA* ; Epithelial Cells ; Epithelium ; Guanine ; Humans* ; Hydroxylation ; Metabolism ; Methylnitrosourea ; Oxygen ; Reactive Oxygen Species ; Urinary Bladder Neoplasms ; Urinary Bladder*

Garlic and mugwort have long been used in traditional medicine to prevent various diseases. Several in vitro studies have reported protective efficacies of garlic and mugwort in cases of gastric cancer. In the present study, we investigated the cancer preventive effects of garlic and mugwort mixture extract (GME) in a Helicobacter (H.) pylori-associated gastric carcinogenesis mouse model. To induce gastric cancer, C57BL/6 mice were treated with N-methyl-N-nitrosourea and H. pylori. Various concentrations of GME (0, 100, 500, and 1,000 ppm) were then fed to the mice for 38 weeks, after which the tumor tissues were examined for histopathology, mucin histochemistry and beta-catenin. The incidence of gastric tumors was significantly lower in the highest dose GME-treated mice (46.7%) than control mice (85.7%) (p < 0.05). The multiplicity and size of tumors were also significantly reduced by GME feeding in a dose-dependent manner (p < 0.01). Furthermore, GME suppressed the H. pylori-associated chronic inflammation measured by histologic grading of H. pylori density, chronic gastritis, glandular atrophy and intestinal metaplasia in non-tumorous gastric mucosae. Our data suggest that GME suppresses gastric tumorigenesis via suppression of H. pylori-associated chronic inflammation.
Animals ; Artemisia* ; Atrophy ; beta Catenin ; Carcinogenesis* ; Garlic* ; Gastric Mucosa ; Gastritis ; Helicobacter pylori ; Helicobacter* ; Incidence ; Inflammation ; Medicine, Traditional ; Metaplasia ; Methylnitrosourea ; Mice* ; Mucins ; Stomach Neoplasms

Garlic and mugwort have long been used in traditional medicine to prevent various diseases. Several in vitro studies have reported protective efficacies of garlic and mugwort in cases of gastric cancer. In the present study, we investigated the cancer preventive effects of garlic and mugwort mixture extract (GME) in a Helicobacter (H.) pylori-associated gastric carcinogenesis mouse model. To induce gastric cancer, C57BL/6 mice were treated with N-methyl-N-nitrosourea and H. pylori. Various concentrations of GME (0, 100, 500, and 1,000 ppm) were then fed to the mice for 38 weeks, after which the tumor tissues were examined for histopathology, mucin histochemistry and beta-catenin. The incidence of gastric tumors was significantly lower in the highest dose GME-treated mice (46.7%) than control mice (85.7%) (p < 0.05). The multiplicity and size of tumors were also significantly reduced by GME feeding in a dose-dependent manner (p < 0.01). Furthermore, GME suppressed the H. pylori-associated chronic inflammation measured by histologic grading of H. pylori density, chronic gastritis, glandular atrophy and intestinal metaplasia in non-tumorous gastric mucosae. Our data suggest that GME suppresses gastric tumorigenesis via suppression of H. pylori-associated chronic inflammation.
Animals ; Artemisia* ; Atrophy ; beta Catenin ; Carcinogenesis* ; Garlic* ; Gastric Mucosa ; Gastritis ; Helicobacter pylori ; Helicobacter* ; Incidence ; Inflammation ; Medicine, Traditional ; Metaplasia ; Methylnitrosourea ; Mice* ; Mucins ; Stomach Neoplasms

The objective of study was to establish an animal model with thymic lymphoma in mice induced by intraperitoneal injection of DNA alkylating agent N-methyl-N-nitrosourea (MNU). Male and female mice of the C57BL/6 strain were injected by the intraperitoneal route with MNU solution in a dosage of 50 mg/kg body weight. The injection was repeated at week 8. Following injection of MNU, the general status of mice was observed. All mice were sacrificed for autopsy at the 22nd experimental week. Complete gross examination was performed for detection of tumor masses. The results showed that at the 22nd week, the incidence of thymic lymphoma in MNU-treated animals was 67.5% (27/40). No significant sex difference in the incidence of thymic lymphoma was observed. In conclusions, an animal model with thymic lymphoma in mice can be established by twice intraperitoneal administration of MNU. The biological behavior of the induced tumors resembles to those of human thymic lymphoma derived from thymic T-cells.
Animals ; Female ; Lymphoma ; chemically induced ; Male ; Methylnitrosourea ; adverse effects ; analogs & derivatives ; Mice ; Mice, Inbred C57BL ; Neoplasms, Experimental ; chemically induced ; Thymus Neoplasms ; chemically induced ; Trimethylsilyl Compounds ; adverse effects