New Evidence on the Size and Possible Effects of a Late Pliocene Oceanic Asteroid Impact

Debris from a late Pliocene asteroid impact is spread across at least 600 kilometers of the ocean floor in the southeast Pacific. On the basis of iridium concentrations in sediments from six deep-sea cores, the asteroid diameter was at least 0.5 kilometer; the impacting projectile may have been one of the largest in the last few million years. The stratigraphic age of this impact is the same as that inferred for the onset of Northern Hemisphere glaciation.

[Sister chromatid exchange in gastric cancer, chronic atrophic gastritis and normal control]

The frequencies of sister chromatid exchange (SCE) in proven cases of 10 chronic atrophic gastritis and 9 gastric cancer were observed together with 10 cases of normal control. They were (1) chronic atrophic gastritis 6.98 +/- 0.89, (2) gastric cancer 7.49 +/- 0.42 and (3) normal control 5.89 +/- 0.57. Statistically, there was a very significant difference in the SCE frequencies between the gastric cancer and normal control groups (P less than 0.001) and a significant difference between the chronic atrophic gastritis and normal control groups (P less than 0.05). However, the difference between the gastric cancer and the chronic atrophic gastritis was not significant (P greater than 0.05). The similarity in the incidence of SCE may offer an evidence for the close relationship theory between gastric cancer and chronic atrophic gastritis.

Electric acupuncture stimulates non-parietal cell secretion of the stomach in dog

Effects of acupuncture and electroacupuncture (EAP) on gastric secretion were studied in the interdigestive state of five conscious dogs prepared with esophagostomy and gastric cannulas. Both EAP and acupuncture without electrical stimulation produced significant increases in gastric secretion of bicarbonate and sodium. At the same time, a marked decrease in gastric secretion of acid was noted. EAP clearly demonstrated a greater effect on gastric secretion within these three parameters than did simple acupuncture. The fact that the effects of EAP and acupuncture on gastric secretion of bicarbonate and sodium were completely blocked by either a local anesthetic agent or anticholinergic agent indicates that gastric secretion involves a somatic afferent-visceral reflex mechanism in which a cholinergic nerve plays a role.