[European guideline for the management of precancerous conditions in the stomach and it's application to Japan].

Atrophic gastritis, intestinal metaplasia, and Helicobacter pylori (H. pylori) infection are commonly recognized as the risk factor of gastric cancer. In Japan mass screening by the X-ray examination or endoscopy has been performed for a long time in general population or in work place because of the high death rate and high incidence of gastric cancer. Periodic endoscopy has been recommended for the subjects with atrophic gastritis and/or intestinal metaplasia to detect gastric cancer in early stage. On the other hand, there was no guideline to manage premalignant conditions such as atrophic gastritis, intestinal metaplasia, and dysplasia in foreign countries. Recently the guideline for the management of precancerous conditions and lesions in the stomach (MAPS) has been published by the combined efforts of the European Society of Gastrointestinal Endoscopy, European Helicobacter Study Group, European Society of Pathology, and the Sociedade Portuguesa de Endoscopia Digestiva. In this article the main statements have been discussed on comparing the understandings as the premalignant conditions in Japan.

Effective induction of oral anaphylaxis to ovalbumin in mice sensitized by feeding of the antigen with aid of oil emulsion and salicylate.

It is important to evaluate the ability of novel proteins in food crops and products to elicit potentially harmful immunologic responses, including allergic hypersensitivity. We developed a novel mouse model of food allergy involving an oral challenge of a protein antigen after feeding of the antigen in combination with modulating factors often ingested in daily life, namely, dietary oil emulsion and salicylate. In the model, BALB/c mice were sensitized orally for three weeks with ovalbumin (OVA) in linoleic acid/lecithin emulsion, followed immediately by intraperitoneal injection of sodium salicylate. At the end of the sensitization, the incidence of mice positive for serum OVA-specific IgG1 but not IgE had significantly increased in the combined-sensitization group. After the 3-week sensitization, a single or double oral challenge with OVA effectively and significantly caused severe anaphylaxis, as compared with the groups sensitized with OVA in the emulsion or the vehicle alone. Moderate increase of plasma histamine and intestinal abnormality in histology was found only in the combined-sensitization group. Anaphylaxis symptoms in the sensitized mice were induced more by oral challenge than by intravenous challenge, suggesting a critical role for the mucosal system. This is the first model for successful induction of oral anaphylaxis in mice sensitized by feeding of food protein without adjuvant. It will be useful to elucidate the mechanism of food allergy and to detect modulating factors of oral allergy at sensitization using this model, which simulates real life conditions.

[Heavy metal-induced immunotoxicity and its mechanisms].

Immunotoxic effects of heavy metals, as a typical environmental agent, and their mechanisms are reviewed based on our findings on autoimmune response induced by exposure to cadmium (Cd) as CdCl(2). Adverse immune effects of chemicals, defined as immunotoxicity, have been used as a sensitive biomarker for assessing health effects of environmental chemicals. My initial research focused on renal toxicity of heavy metals was developed to elucidate characteristics and mechanisms for immune-mediated nephritis induced by heavy metals. In our studies the most interesting finding was autoantibody production enhanced by the oral exposure to Cd at environmental levels. It was observed simultaneously with enhancement of non-specific antibody production and suppression of primed-antigen specific antibody production. Immunostimulation including induction of autoantibodies was found to be the primary immunotoxic effect of Cd, because of the dose-sensitivity, and to be associated with polyclonal B cell activation (PBA). Further mechanism studies on the PBA induced by Cd in vitro showed that it was mediated by T cells, via cytokines, dominantly Type-2 cytokines, and recognition of MHC-II antigens of cell surface. The similarity among PBAs induced by inorganic salts of Cd, mercury and lead suggests that it would be the common effect among the metals to be involved in their pathogenesis of nephritis. Finally possible health significance of chemical-induced PBA is discussed associated with an increasing trend of autoimmune diseases in industrialized countries.

[Mechanism of metallothionein gene activation mediated by heavy-metal dependent transcription factor MTF-1].

Transcriptional activation of metallothionein (MT) genes by heavy metals is a valuable system for understanding the functions of MT as well as the cellular response against heavy metals. Although it is now known that heavy metal signals culminating in MT induction converge upon a transcription factor MTF-1, the mechanism underlying the MTF-1 response to heavy metals has not been elucidated. To address this issue, we investigated various aspects of the in vivo response of MTF-1 against heavy metals. Chromatin immunoprecipitation assay showed that heavy metal-dependent DNA binding of MTF-1 is the critical step in vivo. MTF-1 is primarily localized in the nucleus so that heavy metal-dependent nuclear translocation demonstrated by other groups does not seem to be universal and hence may not be critical for activation of MTF-1. In the six Zn finger motifs, the hallmark of MTF-1, the third and the fourth fingers are essential for the nuclear localization of MTF-1. Furthermore, all fingers except the last are important for transcriptional activation function of MTF-1, suggesting their key role for MTF-1 function. Also, a cysteine cluster structure located in the C-terminal region of MTF-1 is critical for transactivating function of MTF-1. These results suggest a central role of the Zn-finger domain and intramolecular cooperation through a structural change of MTF-1 for its response to heavy metal challenge.

Analysis of human proteins that have an affinity to heavy metals by metal-chelating column chromatography.

To clarify the molecular basis of toxicities of industrial chemicals, it is demanded to develop appropriate methods whereby their cellular target molecules can be directly identified. In the present study, we focused on target proteins of heavy metals and established the method to detect them using a combination of metal-chelating column chromatography and a subsequent analysis by electrophoresis. Protein samples prepared from HeLa cells were applied to the Zn- or Cd-chelating column, and the bound proteins were analyzed by SDS-polyacrylamide gel electrophoresis followed by either silver staining, or fluorography when using radiolabel protein samples. Among several protein species trapped in the columns, a 36-kDa protein apparently has an affinity to both Zn and Cd, indicating the possibility that Cd can exchange essential Zn on this protein. These results suggest that the established method is useful for the target protein screening and further analyses of separated proteins.

[Determination of the optical purity of N-nitrosofenfluramine found in the Chinese slimming diet].

From 2001 to the summer of 2002, more than 800 cases of liver damage were reported in Japan among people taking Chinese diet aids. The Japanese Ministry of Health, Labor and Welfare has recently announced that N-nitrosofenfluramine was the hepatotoxic compound contained in the diet aids based on animal experiments performed by the National Institute of Health Sciences. Although N-nitrosofenfluramine is a derivative of fenfluramine, a previously used antiobesity drug, neither pharmacologic nor toxicologic properties have been reported for N-nitroso fenfluramine. It should be noted that N-nitrosofenfluramine has two optical isomers, although it is not yet known which isomer damages the liver and other organs. The Japanese Ministry of Health, Labor and Welfare has not commented on this point. Pursuing this question, 10 types of Chinese slimming aid samples including those obtained from patients with fulminating hepatitis were analyzed by NMR, GC/MS, and a newly established HPLC method using a chiral separation column. It was found that the N-nitrosofenfluramine in all of the toxic diet aids was the (S)-isomer form. No (R)-isomer was detected. These results strongly suggest that the nitroso-compound in the diets must be prepared from pharmacologically active (S)-fenfluramine (dexfenfluramine). Thus the pharmacologic and toxicologic properties of each isomer should be investigated.