Gastric carcinoma and thrombotic thrombocytopenic purpura: association with plasma immune complex concentrations

A patient with metastatic adenocarcinoma of the stomach developed microangiopathic haemolytic anaemia, thrombocytopenia, renal insufficiency, and fluctuating neurological abnormalities in association with appreciably raised plasma concentrations of immune complexes. This syndrome, similar to thrombotic thrombocytopenic purpura, occurred while the tumour was in sustained objective remission after successful treatment with fluorouracil, doxorubicin, and mitomycin. Reversal of the syndrome was achieved with plasmapheresis, azathioprine, corticosteroids, and antiplatelet treatment; this response was paralleled by a reduction in immune complex concentration, suggesting an immune aetiology for the syndrome. Antibodies eluted from the immune complexes reacted with 50% of cells from the gastric cancer but less than 10% of cells from normal gastric mucosa. There was no reactivity with either carcinoembryonic antigen or mitomycin. A 17S immune complex reacted with a glycoprotein from the patient's autologous platelets and produced platelet aggregation. It is postulated that reducing the tumour and the pre-existing state of antigen excess by chemotherapy allowed soluble antigen-antibody complexes to form and the syndrome to develop.     

The effectiveness of antiarrhythmic agents on early-cycle premature ventricular complexes

Twelve patients completed a double-blind, crossover antiarrhythmic drug trial in which 300 mg of quinidine, 500 mg of procainamide, 100 mg of phenytoin, or placebo was given four times daily on subsequent weeks. Analysis of 24-hour Holter tapes with a computerized analysis system (Argus/H) permitted accurate counting of premature ventricular complexes (PVCs) subclassified according to coupling interval. No antiarrhythmic agent demonstrated a significant overall reduction in the number of PVCs, but both quinidine and procainamide showed a statistically significant (p less than 0.05) reduction of PVCs with coupling intervals less than 400 msec. This effect was noted both in isolated PVCs (quinidine only) and in PVCs that were part of a couplet or run (both drugs). These findings demonstrate that clinically important effects of procainamide and quinidine can occur in the absence of an overall reduction in the number of PVCs.     

Big and little forms of osteoclast activating factor

We have further characterized osteoclast activating factor (OAF) using a bioassay for bone resorption which utilizes the release of previously incorporated (45)Ca from fetal rat long bones in organ culture. When supernatant media from activated leukocyte cultures were concentrated on Amicon PM10 membranes (assigned molecular weight cutoff 10,000 daltons) and chromatographed on Sephadex G-50 columns, the bone-resorbing activity eluted between the molecular weight markers chymotrypsinogen (25,000 daltons) and cytochrome c (12,500 daltons). This peak of biological activity has been called big OAF. When filtrates from the PM10 membranes were concentrated on Amicon UM2 membranes (assigned molecular weight cutoff 1,000 daltons) and chromatographed on Sephadex G-50 columns, some of the biological activity eluted between the molecular weight markers chymotrypsinogen and cytochrome c (big OAF), but there was a separate peak of biological activity which eluted with [(3)H]proline (140 daltons). This second peak has been called little OAF. Little OAF was eluted from Bio-Gel P6 columns between the molecular weight markers calcitonin (approximately 3,500 daltons) and vitamin B(12) (1,330 daltons), but was retained by Spectrapor dialysis tubing (nominal molecular weight cutoff 3,500 daltons). Big OAF was converted to little OAF by equilibration in 1 M NaCl or 2 M urea. Little OAF was self-associated back to big OAF by equilibration in buffers of low ionic strength (Tris-HCl 10-50 mM). Little OAF was extracted into the organic phase in ethyl acetate after acidification of the sample to pH 3.5. The biological activity remained in the aqueous phase after ethyl acetate extraction at pH 7.5-8.4. Little OAF has been purified more than 6,000-fold compared with the original material so that bone-resorbing activity is maximal in a sample with a protein concentration of 80 ng/ml.     

Reaction of hydrogen sulphide with 2-alkenals

Depending on the types of solvent and catalyst, different products are formed in the reaction of hydrogen sulphide with 2-alkenals. The structures of many of these products have been elucidated, and the reaction sequences leading to them are proposed.