Plasma protein-bound sialic acid in patients with colorectal polyps of known histology.

Protein-bound sialic acid (PBSA) was measured in serial plasma specimens from 62 healthy subjects, 48 patients with colorectal polyps, and 30 patients with colorectal adenocarcinomas. The mean plasma PBSA concentration in healthy smokers was significantly greater than that in healthy nonsmokers and healthy ex-smokers (P less than 0.0001). Villoglandular polyps were associated with higher plasma PBSA values than were the most benign hyperplastic polyps (P less than 0.025). Patients with the most neoplastic villoglandular and villous polyps had significantly greater (P less than 0.010-0.050) plasma PBSA values than healthy subjects. Polypectomy decreased the mean PBSA value significantly to the mean value for healthy subjects only for patients with villoglandular (P less than 0.010) or villous (P less than 0.050) polyps. Colorectal cancer patients had mean plasma PBSA concentrations significantly greater than those for the healthy subjects (P much less than 0.001) and the polyp patients (P much less than 0.001). Surgery significantly reduced (P less than 0.025) the mean PBSA value for the cancer patients to the mean PBSA value observed for the healthy subjects.

Comparison of confirmation methods for hepatitis-B antigen and the nature of false-positives detected by 125I-immunoglobulins.

Immunologic specificity associated with solid-phase direct radioimmunoassay (RIA) using guinea pig antibodies for HBsAg detection (Ausria-125TM) was examined further with physicochemical techniques. The RIA reactivities which could not be neutralized by wide-spectrum human anti-HBs serum appeared to be physically distinct from true HBsAg particles; hence, they were truly false-positive, resulting from immunologic cross-reactions. In order to ensure the full advantages of using this highly sensitive RIA test, a confirmatory test using specific human anti-HBs for neutralization is therefore required to distinguish the true- and false-positives. The basic RIA technique is a two-step procedure. Two basic confirmation procedures, namely, a first-step neutralization and a second-step neutralization, were investigated in depth to assess their efficacy and practicality for confirmation. Both procedures were effective for confirmation purposes; however, the first-step neutralization procedure failed to confirm some high-titered HBsAg samples unless these samples were appropriately diluted. The second-step neutralization method did not require dilutions of any test samples.

Intracellular localization of fructose 1,6-bisphosphate aldolase.

Submission of a rat liver homogenate made in 250 mM sucrose-1 mM EDTA to centrifugation between 9,500 times g for 10 min and 105,000 times g for 60 min results in the sedimentation of 60 to 70% of the total cellular fructose 1,6-bisphosphate aldolase (EC 4.1.2.13). Under these conditions only about one-quarter of the total triose phosphate dehydrogenase and phosphoglycerate kinase appears in the microsomal fraction. Ultrastructural immunologic localization techniques have demonstrated that the aldolase is associated with the endoplasmic reticulum, in situ. The binding of this enzyme to the membrane is sensitive to changes in pH with an optimum at 6.0, and to increasing concentrations of NaCl and fructose 1,6-bisphosphate, being about 100-fold more sensitive to the ester than to the inorganic salt.