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Fossilized ichthyosaur offers a prehistoric 'Kinder Surprise' for researchers. Fossilized ichthyosaur offers a prehistoric 'Kinder Surprise' for researchers., Author Affiliations: A fossilized marine reptile's bellyful of a second, slightly smaller marine reptile is visible as a block protruding from its abdomen. Credit: Ryosuke Motani Huge chunk of rock [...]

The polymerase chain reaction using primers to conserved sequences shows a presence of the prohormone convertase (PC) clones PC1/3, PC2, PC5, and furin in the rat antrum. Furin is present in the gastric mucosa, and the amount of PC1/3 and PC2 is more in the mucosa than the muscles. PC1/3 and PC2 are probably produced by endocrine cells, and catalyze the proteolytic cleavage of regulatory peptide precursors. The mRNAs of PCs are selectively processed in different gastric cell types. Their expression is regulated physiologically.

Treatment of the stomach of dog with the 17-norleucine-vasoactive intestinal peptide (17-N-Leu-VIP) inhibits the contractions of the smooth muscle cells. Inhibition is seen when the VIP level becomes almost five times the normal level. The activity of 17-N-Leu-VIP is unaffected by N(super G)-nitro-L-arginine methyl ester (L-NAME) which inhibits nitric oxide. However, the aftereffects of 17-N-Leu-VIP, reduced motilities, are suppressed by L-NAME. Thus, nitric oxide is probably required only when 17-N-Leu-VIP is no longer able to act directly on the muscles.

Starvation and acid inhibition by omeprazole increase the concentration of mRNAs encoding somatostatin receptor2 (SSTR2) in the antrum of the stomach. Starvation increases the level of mRNAs encoding somatostatin in the antrum but acid inhibition decreases somatostatin mRNAs in both antrum and corpus. The antrum contains many subtypes of SSTR which are probably formed by splicing SSTR. SSTR2 is present mainly in the G cells and enterochromaffin-like cells of the antrum.

Gastric chief cells possess somatostatin receptors with a high affinity for somatostatin (SS) and low-affinity for octreotide and resemble SS2 receptors in rat cerebral cortex and SSTR receptor. SS receptor occupation is regulated by agents activating phospholipase C, protein kinase C, adenylate cyclase and (Ca2+)i, although its occupation of SS receptor has no inhibitory effect on pepsinogen release induced by secretagogues acting through either the calcium or cAMP pathway.

The characterization of emulsion and dietary lipids in human stomach reveals that most dietary lipids occur as emulisifed droplets in the stomach. They range in size from 20-40 micrometers. Gastric lipolysis may increase the emulsification process. Lipolysis is catalyzed by gastric lipase and occurs within the first hour of digestion.