Gastric mucosa epithelium

The nitrite results from reduction of nitrate by bacteria abnormally present in the gastric mucosa and the gastric cavity. The bacteria grow situ because the pH is elevated as a result of loss of HCl secretion secondary to the loss of parietal cells and their replacement by intestinal-type epithelium. Parietal cells are lost as a result of chronic atrophic gastritis. What... 

Fig. 3. Immunohistochemical expression of (a) hK7 by the epithelium of eccrine glands of the skin (monoclonal antibody, clone 73.2), (b) hK13 by the epithelium of the bronchus (monoclonal antibody, clone IIC1), (c) hK5 by the ductal epithelium of the parotid gland (polyclonal antibody), (d) hK7 by the esophageal glands (monoclonal antibody, clone 73.2), (e) hK13 by the gastric mucosa (monoclonal antibody, clone 2-17), (f) hK6 by the large intestine mucosa (polyclonal antibody), (g) hK10 in an islet of Langerhans in the pancreas (monoclonal antibody, clone 5D3), (h) hKll by the epithelium of the urinary tubuli (monoclonal antibody), (i) hKll by a papillary renal cell carcinoma (monoclonal antibody).

Thus, along with the secretion of surface epithelium mucus and its mechanical shedding, there must be a constant digestion of mucus by a mucolytic enzyme present in the mucus itself (G26, G33, G34). However, the mechanism of removal of mucus from gastric mucosa with formation of its degradation product, detectable in the gastric juice as "dissolved mucoproteose (G27) needs clarification. 

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... 

High Urinary bladder epithelium, esophageal epithelium, gastric mucosa, and mucus membranes. 

Rats that were administered 2,000 mg/kg/day unleaded gasoline by gavage for 4 weeks were found to have gastric erythema, erosion of the gastric mucosa, and ulceration of the epithelium (Haider et al. 1985). The combined findings in humans and animals demonstrate the irritating effect of gasoline on mucosal tissue. 

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... 

Jovanovic I, Tzardi M, Mouzas lA, et al. Ghanging pattern of cytokeratin 7 and 20 expression from normal epithelium to intestinal metaplasia of the gastric mucosa and gastroesophageal junction. Histol Histopathol. 2002 17 445-454. 

NIS is located in the basolateral cell membranes of both the oxyntic and the pyloric portions of the gastric mucosa in rat, as well as in man (Josefsson et al., 2002 Vayre et ai, 1999). In the rumen parsproventricularis) of rat and mouse no NIS was found (Josefsson et al., 2002), which is not surprising considering that this part of the rodent stomach is lined by squamous epithelium and not gastric... 

Figure 22.2 NIS mRNA in rat gastric mucosa. Section of rat stomach oxyntic mucosa autoradiographically labeled for NIS mRNA by a 33-mer oligonucleotide probe complementary to rat thyroid NIS mRNA 570-602 and 3 -endtailed with S-dATR Intense labeling (black silver grains) is seen in the gastric surface epithelium. Magnification X200.

The type of damage that prostanoids can inhibit has been debated.In rats PGE2 or the prostaglandin precursor, arachidonlc acid, prevented deep necrotic lesions produced in the gastric mucosa by ethanol, but failed to alter the Initial desquamation of the surface epithelium. However, in arachidonlc acid treated animals a continuous layer of surface epithelium had reappeared by 3h, compared to 15h in controls. 

FIGURE 12.2 Normal gastric mucosa (hematoxylin and eosin staining). Note the surface epithelium and fundic glands in the deep portion. 

Hogben CAM. Active transport of chloride by isolated frog gastric epithelium. Origin of the gastric mucosal potential. Am J Physiol 180 641-649, 1955. There are two preliminary communications idem. The chloride transport system of the gastric mucosa. Proc... 

The presence of high concentrations of acid in the normal gastric lumen without damage to the epithelium has always puzzled investigators, given that most cells in the body have an exquisite sensitivity to acidic excursions of pH. This has led to the idea that the gastric mucosa has developed specialized mechanisms to protect itself against acid under the collective sobriquet the... 

The secretion of HCOs by gastric mucosa is at most 10% of acid output. Assuming that the stomach is secreting 100 mM HCl, 10 mM HCOs can be secreted. Hence, this base is not able to neutralize a gastric solution at a pH of 1.0. However, if the stomach is only secreting 10 mM HCl, this can be neutralized by 10 mM HCOj. Secretion of the base could, in principle, then neutralize an unbuffered solution at a pH of 2.0. However, below a pH of 2.0, the neutralizing capadty of the epithelium is exceeded, and gastric surface pH must become addic, since there is no real barrier to proton back diffusion. 

A cartoon depicting the interrelationships between stem cells, committed progenitor cells, and ISEMFs in the gastric mucosa. This is a bidirectional cross talk that allows the epithelium (and its environment) to affect the fate of stem cells via growth factors and the mesenchyme. 

---