RHEUMATOID FACTOR PROPERTIES OF HYPERIMMUNE RABBIT SERA

The rheumatoid factor-like substance (RFLS) induced by hyperimmunization of rabbits with bacteria was consistently and exclusively associated with the macroglobulin fraction of the sera studied. The RFLS is separable from the bulk of serum proteins by zone centrifugation, DEAE cellulose chromatography, and gel filtration. Partially purified preparations of the RFLS were studied by immunoelectrophoretic analysis and analytical ultracentrifugation. Certain RFLS sera demonstrated selective reactivity with one or more rabbit isohemagglutinin antibodies. Pepsin treatment of rabbit γ-globulin removed or greatly diminishes its capacity to react with the RFLS.

CHROMATOGRAPHIC SEPARATION OF PEPSINS FROM HUMAN GASTRIC JUICE

Acid gastric juices have been fractionated on DEAE (diethylaminoethyl)-cellulose to yield three pepsin fractions, which have the same chromatographic mobility as the three pepsin fractions previously described in acidified whole gastric mucosal extracts. The acid gastric juices included specimens obtained from healthy individuals and from patients with peptic ulcer and gastritis. Gastric juice from one patient with pernicious anemia was shown to contain only pepsinogen I. A satisfactory chromatographic separation of pepsins is possible from as little as 4 ml of gastric juice.

SERUM PEPSINOGEN IN THE DIFFERENTIATION OF MEGALOBLASTIC ANAEMIA

Serum pepsinogen levels have been compared in 40 patients with severe megaloblastic anaemia with those obtained from 62 normal subjects, and with levels in 20 patients with pernicious anaemia in remission, 46 patients with iron-deficiency anaemia, and 18 patients with a duodenal ulcer. The range in the normal subjects was 55 to 482 units per ml. It is suggested that a level of below 90 units per ml. should be regarded as indicative of gastric atrophy. It was found to be of value in the early differential diagnosis of severe megaloblastic anaemia. The estimation was found to be reproducible and can be carried out in a routine hospital laboratory.

INTRAMITOCHONDRIAL FIBERS WITH DNA CHARACTERISTICS. II. ENZYMATIC AND OTHER HYDROLYTIC TREATMENTS

The effects of proteolytic enzymes, ribonuclease, and deoxyribonuclease upon a fibrous component of chick embryo mitochondria, which was previously shown to have many fixation and staining properties characteristic of the bacterial nucleoplasm, are reported. Pepsin digestion of formaldehyde-fixed tissues removed the membranes and matrices of mitochondria, but a pepsin-resistant fibrous material remained which was heavily stained by uranyl and lead ions. Experiments on a DNA "model system" showed that DNA treated with osmium tetroxide can be depolymerized by deoxyribonuclease. Zinc ions strongly inhibited the depolymerization of DNA. Digestion of osmium tetroxide-fixed tissues (fixed only briefly) with deoxyribonuclease for 1 hour greatly reduced the Feulgen staining of the nuclei, and after 4 hours the Feulgen reaction was completely abolished. The reduction and the disappearance of the Feulgen reaction in nuclei was paralleled by partial to complete digestion of the mitochondrial fibers in the regions studied (after 1 and 4 hours, respectively), without any other obvious changes in cellular structures. When deoxyribonuclease was inhibited by the addition of zinc ions, the nuclear Feulgen reaction was not diminished, nor were the mitochondrial fibers removed. Buffer control incubations for deoxyribonuclease and ribonuclease did not alter the structure or staining properties of the mitochondrial fibers, nor did incubation with ribonuclease. The latter reaction digested the cytoplasmic and nucleolar ribosomes after a 4-hour incubation period, in parallel with the abolishment of toluidine blue staining. The results contribute further evidence that these mitochondria contain deoxyribonucleic acid.