Epithelium of the stomach

Gastrointestinal Effects. Although data are limited, the only systemic tissue that has been found to be affected following oral exposure is the epithelium of the stomach (Boorman et al. 1986 Danse et al. 1984). This is presumably a result of direct contact between bromomethane and the gastrointestinal epithelium. Based on this effect, an intermediate-duration oral MRL of 0.003 mg/kg/day has been derived. It is likely that this effect (which has only been observed in animals dosed with concentrated solutions of bromomethane dissolved in oil) would be much less pronounced if exposure occurred via ingestion of more dilute solutions of bromomethane in water. However, this has not been studied. 

Lee WA. Alpha-methylacyl-CoA-racemase expression in adenocarcinoma, dysplasia and non-neoplastic epithelium of the stomach. Oncology. 2006 71 246-250. 

The mRNA of C3/33GnT6 is expressed at high levels in the foveolar epithelium of the stomach, in colon, and small intestine, but at low levels in other tissues. In colon cancer tissues, the activity is greatly reduced compared to normal colon, which favors the synthesis of core 1, and might explain the prevalence of the T antigen (core 1) in colon cancer. The mRNA expression of C3/33GnT6 is also reduced in gastric cancer. Consistent with the loss of the enzyme in cancer tissue, the activity is not detectable in many cultured colon... 

The stomach of rats and mice is anatomically different from the human stomach. A part of the stomach in rodents is devoid of glands this part is called the forestomach. The squamous epithelium in the non-glandular rodent forestomach resembles the epithehum covering the esophagus. Therefore, the human esophagus must be regarded as similar with respect to the epithelium of the non-glandular rodent forestomach. 

Figure 3.14. Structure of the stomach. Stomach contains four layers, including the mucosa, submucosa, muscularis, and serosa. The inner infolded mucous layer is made up of columnar epithelium, and gastric pits are found within the infoldings. Submucosa contains connective tissue and vessels, and the muscularis contains muscle fibers. The serosa is on the outside of the stomach and is continuous with the peritoneum.

Results of a multigeneration study in rats given sulfur mustard by gavage showed no significant adverse effects on reproductive parameters at any dose level, but revealed dose-related lesions of the squamous epithelium of the forestomach (acanthosis and hyperplasia). It is likely that the fore stomach lesions were a function of the treatment regimen whereby the bolus dose in an oil vehicle (sesame... 

Human data concerning the toxicity of lewisite via the oral route of exposure are not available. However, there are limited toxicity data on lewisite ingestion from animal studies. In animals, ingestion of lewisite can produce acute inflammation of the mucous membrane of the stomach or intestine, which is characterized by hemorrhage, necrosis of the epithelium, and submucous edema. Developmental effects have been reported in pregnant rats and rabbits... 

The inner surface of the stomach consists of well-defined tissue layers the muscle and the submucosal and mucosal layers. The absorption function of stomach is minimal owing to the limited surface area, lack of villi, thick mucosal layer, and short residence time. The epithelium of the gastric mucosa secretes hydrochloric... 

The equine stomach is lined dorsally by a stratified squamous epithelium and ventrally by a glandular epithelium, which have different functions and susceptibility to peptic injury. The squamous portion of the stomach has no secretory or absorptive function and appears to serve as a reservoir for ingesta. The gastric glandular mucosa has an array of secretory and endocrine functions. 

There is very limited evidence for CYP expression in the human stomach. Furthermore, it is difficult to propose any function for gastric CYPs because the gastric epithelium secretes rather than absorbs. However, the potential of those CYPs expressed in the stomach to play roles in stomach cancer has been investigated in cases of intestinal metaplasia of the stomach. Intestinal metaplasia of the stomach, which involves the replacement of the gastric mucosa with a small intestine-like epithelium (100), is considered to be a precancerous lesion (101). A combination... 

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