Integration of SV40 at 12q23 in SV40-immortalized human bronchial epithelial cells

In four SV40-immortalized human bronchial epithelia] cell lines established in our laboratory, we identified the SV40 integration sites by fluorescence in situ hybridization. We found that in the late passage of all the four cell lines, SV40 integrated at 12q23. It is possible that only SV40 integration at 12q23 is necessary for the immortalization of human bronchial epithelial cells. Some DNA sequences or genes in the region, such as IGF-1, may be involved with a proliferative advantage of the cells with 12q23 SV40 integration.

2q-, a non-random chromosomal abnormality in human non-small-cell lung cancer

Many cytogenetic studies have been carried out on human lung cancer. However the chromosomal alterations in human lung cancers are often complex, making it difficult to identify some abnormal chromosomes by routine cytogenetic studies. Using FISH (fluorescence in situ hybridization), we studied the alterations of chromosome 2, 3, and 17 in four human bronchial epithelial cell lines, two human non-small-cell lung cancer (NSCLC) cell lines, and 12 primary NSCLC specimens. 2q- was found in three out of four human bronchial epithelial cell lines, two NSCLC cell lines, and three out of seven primary NSCLC specimens tested. 3p- was noted in five cases of twelve primary NSCLC patients examined. 3p- was the first cytogenetic discovery and the most prominent abnormality in lung cancer. 2q- has rarely been reported in human lung cancer but loss of heterozygosity by RFLP analysis for 2q had been reported in human NSCLC. Our results indicate that 2q- was also a non-random chromosomal abnormality in the early stage of the development of human NSCLC. There would be one or more putative tumor suppressor gene(s) on the long arm of chromosome 2. Loss of the gene(s) presumably contributes to the carcinogenesis of human non-small-cell lung cancer.

Watershed infarction of spinal cord after the embolization of bronchial artery: a case report

A case of watershed infarction in the spinal cord is reported. The patient underwent bronchial artery embolization for control of massive hemoptysis. The bronchial arteriogram was carefully examined and focused on blood supply to the spinal cord prior to embolization. Acute paraparesis followed the embolization procedure even though there was no visible spinal supply on the arteriogram. Magnetic resonance imaging showed a hyperintensity lesion over the watershed region which is located at the central portion of the upper thoracic cord. This case is reported to emphasize the significant role which angiographically invisible small vessels can play in the blood supply to the spinal cord. The vascular system of the spinal cord and the prevention of spinal cord ischemia secondary to embolization are further discussed here.

Frameshift mutation in codon 176 of the p53 gene in rat esophageal epithelial cells transformed by benzo[a]pyrene dihydrodiol

Mutations in the p53 tumor suppressor gene have been associated with exposure to environmental chemical carcinogens. Cultured rat esophageal epithelial cells were transformed in vitro by treatment with benzo[a]pyrene dihydrodiol (BP-DHD). A BP-DHD-transformed cell line and control cell lines were analyzed for mutations in the p53 gene and in the Ha-ras gene by single-strand conformation polymorphism analysis of polymerase chain reaction-amplified products and direct DNA sequencing. The deletion of one cytosine in codons 174-176 (TGCCCCCAC-->TGCCCCAC) of the p53 gene was found only in the BP-DHD-transformed cell line. The BP-DHD-transformed cells were highly invasive and tumorigenic when transplanted into syngeneic rats, whereas control lines either were nontumorigenic or formed epithelial cysts. BP-DHD-transformed cells and control lines were negative for mutations in the Ha-ras gene. Our results suggest that the tumorigenic potential of the BP-DHD-transformed cell line is associated with a frameshift mutation in codon 176 of the p53 gene but not with mutations in the Ha-ras gene. The G/C-rich codons 174-176 in the rat p53 gene may be specific targets for BP-DHD.

Melkersson-Rosenthal syndrome: a case report

The Melkersson-Rosenthal syndrome (MRS) is a rare disease which includes a triad of orofacial swelling, recurrent facial nerve paralysis and plicated tongue. MRS can still be diagnosed when any two of the conditions are present. Because of its rarity, it is usually ignored and misdiagnosed. Herein, a diabetic female patient with this syndrome, previously diagnosed as Bell's palsy, is described. This case report is presented to encourage awareness of this entity among medical practitioners. In addition, the MRS literature is reviewed with respect to incidence, etiology, clinical features, pathology, differential diagnosis and treatment.

[A study on the diagnosis of pulmonary tuberculosis and silicotuberculosis by PCR]

The sputa of 156 patients with lung disease were detected by smear, culture and PCR for mycobacterium tuberculosis. The detectable limitation was 10 fg DNA and 5 organisms. Both sensitivity and specificity of detection by PCR were much better than smear or culture techniques. Our results demonstrated that PCR technique is one of the useful tools in early and rapid diagnosis of pulmonary tuberculosis and silicotuberculosis.

In vitro transformation of rat esophageal epithelial cells by fusarin C

Fusarin C (FC) is a mutagenic and carcinogenic mycotoxin which was isolated from Fusarium moniliforme culture extracts. The Fusarium moniliforme is one of most prevalent fungi found on corn in Linxian, a high risk area for esophageal cancer. This paper reports, for the first time, the malignant transformation of rat esophageal epithelial cells induced by FC. The transformed cells showed several characteristics of transformation. Colonies were formed after seeding these transformed cells either into selective medium free of epidermal growth factor (EGF) and serum, or on semi-solid agar; there was an increase in chromosome number; the expression of c-myc and v-erb-B oncogenes was enhanced in the cells; and squamous cell carcinomas arose after inoculating the cells into nude mice. The results demonstrated transforming effect of FC on rat esophageal epithelial cells, and indicate that the abnormal expression of some oncogenes could serve as a new property of transformed cells.

[Inhibitory effect of green tea extract on promotion and related action of TPA]

Polyphenol components isolated from green tea showed strong antioxidant activity. The green tea extract (GTE) significantly inhibited the promoting effect of TPA in BALB/3T3 cell transformation assays. In in vivo experiments, GTE inhibited edema induced by TPA in mouse ear. The inhibitory effect of GTE on the induction of ornithine decarboxylase activity was also found in mouse skin treated with TPA. GTE decreased the frequency of SCE induced by oxygen radical in IAR 20 liver cells treated with hypoxanthine and xanthine oxidase. Mechanisms of the antipromoting effect of GTE are discussed. Our experimental results suggest that GTE may have some practical use in cancer prevention.

Antimutagenic activity of green tea polyphenols

For centuries green tea has been a widely consumed beverage throughout the world. It is known to contain a number of pharmacologically active compounds. In this study water extracts of green tea (WEGT) and their major constituents, green tea polyphenols (GTP), were examined for antimutagenic activity. WEGT and GTP were found to significantly inhibit the reverse mutation induced by benzo[alpha]pyrene (BP), aflatoxin B1 (AFB1), 2-aminofluorene, and methanol extracts of coal tar pitch in Salmonella typhimurium TA100 and/or TA98 in the presence of a rat-liver microsomal activation system. GTP also inhibited gene forward mutation in V79 cells treated with AFB1 and BP, and also decreased the frequency of sister-chromatid exchanges and chromosomal aberrations in V79 cells treated with AFB1. The addition of GTP during and after nitrosation of methylurea resulted in a dose-dependent inhibition of mutagenicity. Studies to define the mechanism of the antimutagenic activity of GTP suggest that it may affect carcinogen metabolism, DNA adduct formation, the interaction of ultimate carcinogen or the scavenging of free radicals.

Prevention of cytotoxicity and inhibition of intercellular communication by antioxidant catechins isolated from Chinese green tea

An antioxidant fraction of Chinese green tea (green tea antioxidant; GTA), containing several catechins, has been previously shown to inhibit 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced tumor promotion in mouse skin. In the present study, GTA was shown to have antioxidative activity toward hydrogen peroxide (H2O2) and the superoxide radical (O2-). GTA also prevented oxygen radical and H2O2-induced cytotoxicity and inhibition of intercellular communication in cultured B6C3F1 mouse hepatocytes and human keratinocytes (NHEK cells). GTA (0.05-50 micrograms/ml) prevented the killing of hepatocytes (measured by lactate dehydrogenase release) by paraquat (1-10 mM) and glucose oxidase (0.8-40 micrograms/ml) in a concentration-dependent fashion. GTA (50 micrograms/ml) also prevented the inhibition of hepatocyte intercellular communication by paraquat (5 mM), glucose oxidase (0.8 micrograms/ml), and phenobarbital (500 micrograms/ml). In addition, GTA (50 micrograms/ml) prevented the inhibition of intercellular communication in human keratinocytes by TPA (100 ng/ml). Cytotoxicity and inhibition of intercellular communication, two possible mechanisms by which tumor promoters may produce their promoting effects were therefore prevented by GTA. The inhibition of these two effects of pro-oxidant compounds may suggest a mechanism by which GTA inhibits tumor promotion in vivo.

Scavenging effect of extracts of green tea and natural antioxidants on active oxygen radicals

With the use of the spin trapping methods, the scavenging effects of the extracts of green tea and other natural foods are studied. In stimulated polymorphonuclear leukocytes (PMN) system, water extract fraction 6 (F6) from green tea and green tea polyphenols (GTP) have the strongest scavenging effect on the active oxygen radicals, much stronger than vitamin C (Vc) and vitamin E (VE). Rosemary antioxidants (RA) and Curcumin (Cur) have weaker scavenging effects than Vc, but stronger than VE. In Fenton Reaction, Cur has the strongest scavenging effect (69%) on hydroxyl radicals. In irradiation, riboflavin system F6(74%) and GTP(72%) have very strong scavenging effects that are weaker than Vc, but much stronger than VE (23%). With the use of spin probe oxymetry, the oxygen consumption in respiratory burst of stimulated PMN were measured when the antioxidants existed in these systems. The results demonstrated that these antioxidants did not affect the respiratory burst of human polymorphonuclear leukocytes stimulated with PMA.

Inhibition of aflatoxin B1 mutagenesis in Salmonella typhimurium and DNA damage in cultured rat and human tracheobronchial tissues by ellagic acid

Ellagic acid (EA), a plant phenol found in various fruits and nuts, was examined for its ability to inhibit aflatoxin B1 (AFB1) mutagenesis in strain TA 100 of Salmonella typhimurium. In the presence of rat liver S-9 microsomal preparation, EA (1.5 microgram/plate) inhibited the number of mutations induced by AFB1 (0.5 microgram/plate) by 50%. EA at a dose of 1000 micrograms/plate inhibited the mutation frequency by greater than 90%. EA was also tested for its ability to inhibit the DNA binding and adduct formation of AFB1 in cultured explants of rat trachea and human tracheobronchus. Explants were incubated in medium containing EA at concentrations of 10, 50 and 100 microM for 16 h followed by the addition of 1 microM [3H]AFB1 and EA for 24 h. DNA was isolated by phenol extraction and hydroxylapatite chromatography. EA caused a dose-dependent inhibition in the covalent binding of AFB1 to the DNA of both the rat trachea (9-57% inhibition) and human tracheobronchus (24-79% inhibition). After acid hydrolysis of the isolated DNA, the AFB1-DNA adducts were separated by h.p.l.c. In tissues from both species, the major AFB1- DNA adducts were AFB1-N7-Gua [8,9-dihydro-8-(N7-guanyl)-9-hydroxyAFB1] and AFB1-N7-FaPyr (major) [8,9-dihydro-8- (2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl formamido)-9-hydroxyAFB1], and the formation of these adducts was reduced by 28-76% in the presence of EA. These data indicate that EA has the potential to act as a naturally occurring inhibitor of AFB1-related respiratory damage in rats and in humans.

[Preliminary study on the antimutagenesis of vegetables and fruits]

Possible antimutation of 108 preparations of 91 kinds of vegetables and fruits on Salmonella typhimurium TA98 and TA100 mutants was tested. 4-nitroquinoline-N-oxide (4 NQO), N-methyl-N-nitro-N-nitrosoguanidine (MNNG), aflatoxin B1 (AFB1) and benzo (a) pyrene (BaP) were used as mutagens. The results showed that 67 (62%) preparations had antimutagenic action in vitro to different degrees. 9.6% of all preparations showed inhibition action on 4 NQO in TA100 mutant and 12.3%, in TA98, 5% on MNNG in TA100, 38% on AFB1 in TA100 and 45.1% in TA98, 28.9% on BaP in TA100. This experiment provides a scientific basis to the study of food resources as prevention of carcinogenesis.

Ventricular septal defect in Chinese with aortic valve prolapse and aortic regurgitation

The incidence of aortic valve prolapse and aortic regurgitation (AR) among Chinese with ventricular septal defect (VSD) has not been studied, and controversies still exist regarding optimal surgical treatment and timing of operation for this condition. A prospective study of 332 consecutive patients with VSD showed that aortic valve prolapse and AR occurred in 43 (11.9%) patients. Valve lesions occurred more commonly among patients with subpulmonic VSD (28.0%) than with subaortic VSD (8.8%) (P less than 0.005). A retrospective study of another 306 patients revealed that 37 (12.1%) had valve complications. Of the 80 patients with valve lesions, 60 were males and 20 were females. The youngest ages of prolapse and AR in subpulmonic VSD were 7 months and 3 years 8 months, respectively; those in subaortic VSD were 2 years and 3 years 6 months, respectively. Valve prolapse occurred mostly before the age of 6-10 years, leading progressively to AR. The coronary cusps prolapsed in subpulmonic VSD were limited to the right cusp; and those in subaortic VSD were the right cusp, noncoronary cusp, or both. The magnitude of left-to-right shunts was small and the pulmonary artery pressure was normal in the majority of patients. Seventy-two patients underwent open-heart closure of the VSD, with additional valvuloplasty in 15 and valve replacement in three patients. It is concluded that Chinese with VSD are prone to develop aortic valve complications. Surgical closure of the subpulmonic VSD may restore the prolapsed valve to normal. Closure of the subaortic VSD has little effect. Valvuloplasty in subaortic VSD may palliate AR, but in all probability cannot restore valve competency.

[Micronucleus test in cultured cells--preliminary study]

In mutagenicity and carcinogenicity assays using micronucleus test, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 50 mg/kg or benzo(a)pyrene (BaP), 100 mg/kg did not increase the incidence of micronuclei in polychromatic erythrocytes in bone marrow of mice. MNNG, 0.1 microgram/ml could induce a significant increase of micronuclei with dose response in cultured V79 cells. In another experiment of Syrian hamster embryo cells, the induction of micronuclei was seen after benzo(a)pyrene, 0.1 microgram/ml treatment. The combined use of micronucleus test in vivo and in vitro can increase the sensitivity and reduce the false negativity obtained in vivo micronucleus test.

Occurrence of nitroso compounds in fungi-contaminated foods: a review

Dimethylnitrosamine (NDMA), diethylnitrosamine (NDEA), methylbenzylnitrosamine, and a new N-nitroso compound, N-3-methylbutyl-N-1-methylacetonylnitrosamine (NMAMBA), were found in cornbread that was inoculated with Fusarium moniliforme and underwent an incubation and the addition of a small amount of NaNO2. The carcinogenicity of NMAMBA was shown by the induction of forestomach carcinomas and liver tumors in mice and rats. Another new nitrosamine, N-2-methylpropyl-N-methylacetonyl nitrosamine, was isolated in millet and wheat flour after similar treatment. Some species of fungi not only can reduce nitrates to nitrites but also can increase the amount of secondary amines in the moldy foods and provide favorable conditions for the synthesis of nitrosamines. Some fungi may utilize primary amines to synthesize nitrosamines in appropriate culture mediums. Furthermore, the cornmeal may naturally contain trace amounts of nitrosamines, as detected by a gas chromatography/thermoenergy analyzer. Prolonged feeding of F. moniliforme-inoculated cornbread alone also induced the development of forestomach carcinoma in rats. This indicates the occurrence of potential carcinogens, perhaps certain Fusarium mycotoxins, in the moldy cornbread in addition to the carcinogenic nitrosamines. Another nitroso compound, Roussin red methylester (di-mu-methanethiolatotetranitrosodiiron) was found in pickled vegetables that are eaten daily in the Linxian (China) area. Roussin Red may provide NO-2 ions, which would react readily with secondary amines to form nitrosamines. Possibly this compound is a natural tumor promoter and is able to induce epithelial hyperplasia of the upper digestive tract and forestomach papilloma in treated mice. Also, trace amounts of NDMA, NDEA, and some other nitrosamines were found in the extract of pickled vegetables.

A comparative study on mutagenesis of methylbenzylnitrosamine in V79 cells co-cultivated with liver or esophageal epithelial cells from chickens, rats and humans

Cell-mediated activation of methylbenzylnitrosamine (MBN) to mutagenic metabolites was detected by the induction of forward gene mutation and sister chromatid exchange (SCE) in V79 cells co-cultivated with hepatocytes or esophageal epithelial cells from humans, rats or chickens. In the rat and chicken hepatocyte-mediated mutagenesis, a significant increase in SCE and 6-thioguanine resistant (6-TGr) mutants was noted in V79 cells exposed to MBN. The induction of 6-TGr mutant was also noted in V79 cells co-cultivated with human fetal hepatocytes, but the increase in SCE was trivial. In the assay of rat esophageal epithelial cell-mediated mutagenesis, MBN could be activated significantly to mutagenic metabolites to induce SCE and 6-TGr mutants in V79 cells, but this nitrosamine did not show any mutagenic action on V79 cells co-cultivated with chicken esophageal cells. No esophageal carcinoma was found in 26 Leghorn cocks treated with MBN for as long as 975 days, the largest total dose being 1674.86 mg. The experimental results show that chicken esophagus is probably not susceptible to the carcinogenic action of common volatile nitrosamines. At the present time, there is no evidence to indicate that the development of pharyngo-esophageal carcinoma in Linxian chickens was due to the volatile nitrosamines that occurred in the local foods. The human esophageal epithelial cells showed a certain ability to activate MBN to metabolites mutagenic to V79 cells, but this ability was much lower with human esophageal cell activation than with rat cells. Further studies are required to elucidate the importance of nitrosamines in the etiology of human esophageal carcinoma in the high-incidence areas.

[Studies on a new mutagen produced by fusarium moniliforme isolated in Linxian County]

A new mutagen, Fusarin C has been recently isolated and identified from corn meal inoculated with Fusarium moniliforme, one of the most common fungus pollutant of corn in Linxian County, a high-risk area of esophageal cancer. Fusarin C significantly induced sister chromatid exchange (SCE), micronucleus increase, chromosome aberrations, and 6-thioguanine resistant mutants in V 79 cells in the presence of microsomal preparations. Fusarin C also induced 6-thioguanine resistant mutants in V 79 cells cocultured with primary rat liver cells. The toxic action of Fusarin C on V 79 cells was much stronger in the absence of the microsomal preparations. However, Fusarin C did not show, at the highest concentration, any significant mutagenic or chromosomal damage on V 79 cells without the addition of the metabolic activation system. The possible relationship between the consumption of corn contaminated with Fusarium moniliforme and the etiology of esophageal cancer is discussed.

A mutagenic metabolite produced by Fusarium moniliforme isolated from Linxian county, China

Fusarin C, a fungal metabolite, was recently isolated and identified from corn meal inoculated with Fusarium moniliforme which was one of the most common fungi associated with corn in Linxian county, a high-incidence area of esophageal cancer. In the presence of S-9 mix, fusarin C significantly increased the number of revertants in Salmonella typhimurium TA 100, and induced SCE, micronuclei, chromosome aberrations and 6-TG resistant mutants in V79 cells. The toxic action of fusarin C on V79 cells was much stronger in the absence of S-9 mix. However, fusarin C did not show, at the largest concentration used, any significant mutagenic or clastogenic effect on the cells without the addition of S-9 mix. The possible relationship between the consumption of corn contaminated with F. moniliforme and the cause of esophageal cancer was discussed.