Adenoviruses are icosahedral virions containing double-stranded linen DNA. They are 70 nm to 90 nm in diameter and capsid is composed of 252 capsomeres. Several members of this group, including types commonly associated with respiratory disease in man, are capable of producing malignant tumors in young hamsters and a few types have been shown to be oncogenic in young rat. Previous report involving effect of caffein on transformation induced by Adenovirus type 12 [9] has been carried out. The present report represents a continuation of previous study. To obtain evidence concerning the of(tract of MNNG (N-methyl-N'-nitro-N-nitroguanidine) on transformation, investigation of adenovirus type 12 of this group was undertaken. For practical consideration it was desirable to investigate the effect of MNNG on the adenovirus type 12-induced transformation in L cell. Results were as following 1. Adeno virus type 12 induced transformation was enhanced in the presence of MNNG. 2. Yields of adeno type 12 virus in L cell were slightly inhibited by treatment of MNNG.
Adenoviridae* ; Animals ; Bedding and Linens ; Capsid ; Cricetinae ; DNA ; Methylnitronitrosoguanidine ; Rats ; Virion

A fungal strain producing a high level of cellulase was selected from 320 fungal isolates and identified as Aspergillus sp. This strain was further improved for cellulase production by sequential treatments by two repeated rounds of gamma-irradiation of Co60, ultraviolet treatment and four repeated rounds of treatment with N-methyl-N'-nitro-N-nitrosoguanidine. The best mutant strain, Aspergillus sp. XTG-4, was selected after screening and the activities of carboxymethyl cellulase, filter paper cellulase and beta-glucosidase of the cellulase were improved by 2.03-, 3.20-, and 1.80-fold, respectively, when compared to the wild type strain. After being subcultured 19 times, the enzyme production of the mutant Aspergillus sp. XTG-4s was stable.
Aspergillus ; beta-Glucosidase ; Cellulase ; Mass Screening ; Methylnitronitrosoguanidine ; Mutagenesis ; Sprains and Strains

OBJECTIVETo investigate the function of POLH(polymerase eta) through establishment of the POLH gene-blocked cell line FL-POLH(-).

METHODSA mammalian expression vector expressing antisense POLH gene fragment pMAMneo-amp-POLHA (-) was constructed by cloning the 1473 - 2131 fragment of POLH gene into the mammalian expression vector pMAMneo-amp(-) in antisense orientation. The FL cells were transfected with this antisense RNA expressing vector and selected by G418. The mutation assay was conducted using the shuttle plasmid pZ189.

RESULTThe spontaneous mutation frequency of SupF tRNA gene in the plasmid replicated in the FL-POLH(-) was 13.5 x 10(-4), while it was 4.9x10(-4) and 3.7x10(-4) in the control cells FL and FL-M, respectively. The nontargeted mutation frequency of SupF tRNA gene decreased in the plasmid replicated in these cell lines pretreated with MNNG.

CONCLUSIONPOLH plays an important role in maintenance of genetic stability and genesis of nontargeted mutation.

Antisense Elements (Genetics) ; pharmacology ; Cell Line ; DNA-Directed DNA Polymerase ; genetics ; physiology ; Methylnitronitrosoguanidine ; toxicity ; Mutagenesis

Human epithelial cell line immortalized by Ad12-SV40 hybrid virus was transfected with plasmid containing HPV-16 via calcium-phosphate method. Subsequently, 8 clonal cell lines were obtained after G418 selection. Among these clonal cells, clonal cell-4(C-4) and clonal cell-6(G-6) showed increases of tumorigenic cellular properties such as saturation density, soft agar colony formation and cell aggregation. Morphological alteration such as appearane of foci was observed on these two clones after passage 6 and 7(50 to 55 days after transfection). When clonal cells and control cells were treated with MNNG(0.01ug/ml), both C-4 and C-6 showed increases of tumorigenic cellular properties and the level of increase was much more elevated as compared to clonal cells prior to MNNG treatment. Appearance of foci formation was observed in C-4 and C-6 after passage-6. After passage-8, control cells and all clonal cells showed morphological alterations. It seems that treatment of cells containing HPV-16 DNA with MNNG increases tumorigenic properties of the cells and expedite morphological transformations. (continue)
Agar ; Cell Aggregation ; Cell Line ; Clone Cells ; DNA ; Epithelial Cells* ; Human papillomavirus 16 ; Humans* ; Methylnitronitrosoguanidine ; Plasmids

Gastric cancer(GC), one of the most common malignancies worldwide, seriously threatens human health due to its high morbidity and mortality. Precancerous lesion of gastric cancer(PLGC) is a critical stage for preventing the occurrence of gastric cancer, and PLGC therapy has frequently been investigated in clinical research. Exploring the proper animal modeling methods is necessary since animal experiment acts as the main avenue of the research on GC treatment. At present, N-methyl-N'-nitro-N-nitroso-guanidine(MNNG) serves as a common chemical inducer for the rat model of GC and PLGC. In this study, MNNG-based methods for modeling PLGC rats in related papers were summarized, and the applications and effects of these methods were demonstrated by examples. Additionally, the advantages, disadvantages, and precautions of various modeling methods were briefly reviewed, and the experience of this research group in exploring modeling methods was shared. This study is expected to provide a reference for the establishment of MNNG-induced PLGC animal model, and a model support for the following studies on PLGC.
Animals ; Gastric Mucosa ; Methylnitronitrosoguanidine/toxicity* ; Precancerous Conditions/chemically induced* ; Rats ; Stomach Neoplasms/drug therapy*

Activation of c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase family, is an important cellular response that modulates the outcome of the cells which are exposed to the tumor necrosis factor (TNF) or the genotoxic stress including DNA damaging agents. Although it is known that JNK is activated in response to genotoxic stress, neither the pathways to transduce signals to activate JNK nor the primary sensors of the cells that trigger the stress response have been identified. Here, we report that the receptor interacting protein (RIP), a key adaptor protein of TNF signaling, was required to activate JNK in the cells treated with certain DNA damaging agents such as adriamycin (Adr) and 1-beta-D-arabinofuranosylcytosine (Ara-C) that cause slow and sustained activation, but it was not required when treated with N-methyl-N-nitro-N-nitrosoguanidine (MNNG) and short wavelength UV, which causes quick and transient activation. Our findings revealed that this sustained JNK activation was not mediated by the TNF (tumor necrosis factor) receptor signaling, but it required a functional ATM (ataxia telangiectasia) activity. In addition, JNK inhibitor SP-600125 significantly blocked the Adr-induced cell death, but it did not affect the cell death induced by MNNG. These findings suggest that the sustained activation of JNK mediated by RIP plays an important role in the DNA damage-induced cell death, and that the duration of JNK activation relays a different stress response to determine the cell fate.
Cell Death ; DNA ; DNA Damage ; Doxorubicin ; Humans ; JNK Mitogen-Activated Protein Kinases ; Methylnitronitrosoguanidine ; Necrosis ; Protein Kinases ; Tumor Necrosis Factor-alpha

Spores of Aspergillus sp. SU14 were treated repeatedly and sequentially with Co60 gamma-rays, ultraviolet irradiation, and N-methyl-N'-nitro-N-nitrosoguanidine. One selected mutant strain, Aspergillus sp. SU14-M15, produced cellulase in a yield 2.2-fold exceeding that of the wild type. Optimal conditions for the production of cellulase by the mutant fungal strain using solid-state fermentation were examined. The medium consisted of wheat-bran supplemented with 1% (w/w) urea or NH4Cl, 1% (w/w) rice starch, 2.5 mM MgCl2, and 0.05% (v/w) Tween 80. Optimal moisture content and initial pH was 50% (v/w) and 3.5, respectively, and optimal aeration area was 3/100 (inoculated wheat bran/container). The medium was inoculated with 25% 48 hr seeding culture and fermented at 35degrees C for 3 days. The resulting cellulase yield was 8.5-fold more than that of the wild type strain grown on the basal wheat bran medium.
Aspergillus ; Cellulase ; Dietary Fiber ; Fermentation ; Hydrogen-Ion Concentration ; Magnesium Chloride ; Methylnitronitrosoguanidine ; Polysorbates ; Seeds ; Spores ; Sprains and Strains ; Starch ; Triticum ; Urea

Eighty rats out of 233 developed malignant tumors in the stomach and small intestine by administration of 100 micrograms/ml N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water for 28 weeks. Fifteen lesions (30%) among the 50 small intestinal carcinomas showed ossification in the tumor, while none in the sarcomas (12 lesions) or gastric adenocarcinomas (59 lesions) showed ossification. Multifocal heterotopic bone formation was found within stroma in close approximation to the neoplastic glands. The islands of bone trabeculae were covered by osteoblast-like cells, and abundant fibroblasts in loose stroma gathered around the bony islands which enclosed osteocytes in lacunae. Neither osteoclast nor cartilage was identified. In 5 cases, ossification was extensive, which comprised the major portion of the stroma. In contrast, intraluminal calcification without ossified foci were occasionally seen in the gastric carcinoma. Ossification of the intestinal tumors correlated to the degree of mucin content (p<0.05, chi square with Yates' correction), degree of neutrophilic infiltration (p<0.05), and size of the tumor (p<0.1). (The average size of the ossified tumor was 21.5 +/- 4.0 mm, while that of nonossified tumors was 12.5 +/- 1.9 mm). The degree of tumoral necrosis, desmoplasia or depth of invasion did not seem to be related to the ossification of the tumor. The ossification rate of this experimental model was much higher than in human cases. Various histologic alterations, such as mucin leakage, inflammatory cell infiltration, necrosis and/or fibrosis, which might be caused by continuous stimulation of the strong carcinogen, may play some role in the ossification of experimental tumors.
Adenocarcinoma/chemically induced/*pathology ; Animals ; Intestinal Neoplasms/chemically induced/*pathology ; Intestine, Small/*pathology ; Methylnitronitrosoguanidine ; Ossification, Heterotopic/*pathology ; Rats ; Rats, Sprague-Dawley ; Staining and Labeling ; Stomach Neoplasms/chemically induced/*pathology

The purpose of this study is to elucidate the participation of Paneth cells in experimentally induced adenocarcinoma of the intestine. The rats were fed with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) dissolved in drinking water ad libitum at a concentration of 100 micrograms/ml for 28 weeks. They were sacrificed 12 weeks after the last MNNG administration. A number of tumor cells containing large eosinophilic granules in their supranuclear cytoplasm (Paneth cells) were observed in about 20% of the experimentally induced adenocarcinoma of the small intestine. The granules were stained positively with Lendrum, periodic acid-Schiff, Masson's trichrome, and Mallory's phosphotungstic acid hematoxylin. Ultrastructurally, the granules were round, osmiophilic, and relatively even in size. We compared the morphologic features of the Paneth cell-containing small intestinal adenocarcinomas (Group I) with those without Paneth cells (Group II). Group I was distinguished from Group II by its better differentiation, larger tumor size and lower incidence of calcification. Although Paneth cells are extremely rare in human gastrointestinal carcinomas, twenty percent of MNNG-induced intestinal carcinomas harbor Paneth cells. The neoplastic Paneth cells in experimental carcinomas may differentiate from uncommitted cells in the deeper portion of the crypt.
Adenocarcinoma/chemically induced/*ultrastructure ; Animals ; Cell Transformation, Neoplastic/chemically induced/ultrastructure ; Intestinal Neoplasms/chemically induced/*ultrastructure ; *Methylnitronitrosoguanidine ; Rats ; Rats, Inbred Strains

OBJECTIVETo characterize the DNA damage property represented by the distinct whole nucleus stain pattern of gammaH2AX induced by N-methyl-No-nitro-N-nitrosoguanidine (MNNG).

METHODSMNNG-induced gammaH2AX foci formation in human amnion FL cells was observed by immunofluorescent microscopy. DNA double-stranded breaks (DSBs) were detected by neutral comet assay. General DNA damages were detected by alkaline comet assay.

RESULTA distinct whole nucleus stain pattern of gammaH2AX was induced by high concentration MNNG (10 mg/L). 1 mg/L MNNG also induced this type of stain pattern in a small fraction of cells, although the effect was transient. Neutral comet assay did not detect any significant DSBs formation in this type of cells, while alkaline comet assay revealed the presence of DNA damage.

CONCLUSIONAlthough normal gammaH2AX foci were regarded as a biomarker for DSBs, the whole nucleus stain pattern might represent DNA damage other than DSBs.

Amnion ; cytology ; Cell Nucleus ; drug effects ; metabolism ; Comet Assay ; DNA Breaks, Double-Stranded ; drug effects ; DNA Damage ; Histones ; analysis ; Humans ; Methylnitronitrosoguanidine ; pharmacology ; Microscopy, Fluorescence ; Phosphoproteins ; analysis