Effect of gastric mucus on the uptake of the carcinogen MNNG by gastric mucosal DNA.

In prostaglandin E2 (PGE2)-, pirenzepine-, and indomethacin-administered rats, the incorporation of N-[methyl-3H]-N'-nitro-N-nitrosoguanidine ([methyl-3H]MNNG) into gastric mucosal DNA was measured quantitatively by liquid scintillation counting after intragastric instillation of [methyl-3H]MNNG. The amount of incorporation was 25.4 +/- 5.9 pmol/mg DNA in control rats, 11.7 +/- 3.8 pmol/mg DNA in PGE2-administered rats, 6.2 +/- 5.6 pmol/mg DNA in pirenzepine-administered rats, and 42.9 +/- 14.4 pmol/mg DNA in indomethacin-administered rats. PGE2 and pirenzepine significantly decreased the incorporation as compared with the control group. In contrast, indomethacin increased the incorporation. In addition, gastric mucosa of these drug-treated rats was studied histochemically. PGE2 and pirenzepine increased secretion of gastric mucus whereas indomethacin decreased it. It is possible that gastric mucus has a protective effect not only against ulcerogenic agents but also against carcinogens. It is considered that gastric mucus plays an important role in the defense mechanism against carcinogenesis.

[An autopsy case of a patient with myasthenia gravis who showed various symptoms of collagen diseases and complicated with malignant thymoma].

A 37-year-old man suffered from photosensitivity and urinary casts with serological findings of positive anti-DNA antibody, LE cells and false positive VD reaction in September of 1979. He developed general fatigue, dyspnea and diplopia with ptosis of bilateral eyelids in November of 1979, which were improved by the anti-cholinesterase drugs. In January of 1980, he had an attack of unconsciousness and his chest X-ray film showed several tumorous shadows in the anterior mediastinum and middle and lower lung fields. Treating him with chemotherapy of VEMP, the pulmonary shadows disappeared. However, he developed severe muscle weakness with an elevated CPK (430 mU/ml) and a myogenic EMG pattern along with an increased anti-acetylcholine receptor antibody (243 n Mol/l), dysphagia and eyelid-ptosis. He died in September of 1985 and his autopsy disclosed a malignant thymoma of mixed type in the anterior mediastinum and an atrophy and fibrosis with infiltration of inflammatory cells in the striated muscles.

Nonparticipation of C1q in the decrease of complement activity in the cold in sera of patients with chronic liver diseases.

Serum and plasma samples taken simultaneously from 560 patients with various diseases were examined for hemolytic complement activity (CH50) after incubation at 4 degrees C for 20 h. Serum CH50 titers less than 20 U/ml were observed in 39 cases and among them, a difference between serum and plasma CH50 of more than 5 U/ml were observed in 16 cases. Diagnosis of most of them were chronic liver diseases. To analyze the dissociation of CH50 titers between serum and plasma, sequential estimations of CH50 were performed on serum and plasma samples which showed the dissocation incubated at 4 and 37 degrees C. Marked decrease in CH50 titers was obtained in sera but not in plasma incubated at 4 degrees C. In such sera, however, no significant decrease of protein amount and agglutinating activity of C1q was observed. The result could indicate that C1q would not participate in the decrease of serum hemolytic activity in the cold, suggesting an activation of complement other than the classical pathway.