Characterization of two monoclonal antibodies in an immunohistochemical study of keratin 8 and 18 expression

Two monoclonal antibodies, UCD/AB 6.11 and UCD/PR 10.11, were evaluated for their patterns of immunohistochemical reactivity in a survey of paraffin-embedded human tissues by the avidin-biotin-immunoperoxidase technique. By two-dimensional immunoblotting, UCD/AB 6.11 reacts with keratin number 18 and UCD/PR 10.11 identifies both keratin numbers 8 and 18, the major keratins found in human simple epithelial cells. Both antibodies have excellent signal-to-noise ratios, and specifically react with simple epithelia, transitional epithelia, mesothelia and tumors derived from such tissues, making them superior immunological reagents. They do not react with neural, muscle, hematopoietic, connective or most epidermal tissues. However, within a given tissue or cell type, differences in the distributions of the antigens recognized by these two antibodies can be observed, raising the possibility of differential expression, modification, or masking of the keratin epitopes revealed by UCD/AB 6.11 and UCD/PR 10.11.

Immunological activities of recombinant interferon-alpha 2 and its A fragment

The immunomodulating effects of the A fragment of recombinant human interferon-alpha 2 (rIFN-alpha 2) generated by thermolysin treatment was compared to that of the intact rIFN-alpha 2 and lymphoblastoid IFN. The A fragment was similar to intact IFN in augmenting natural killer (NK) activity and suppressing the proliferation of certain cell lines, but it failed to inhibit human polyclonal immunoglobulin production; rIFN-alpha 2 and lymphoblastoid IFN were equally effective in suppressing this in vitro system. These data suggest that the A fragment mediates certain, but not all, of the immunomodulating properties of IFN-alpha 2.

Analysis of the steady state binding, internalization, and degradation of human interferon-alpha2

Scatchard analyses of the equilibrium binding of radiolabeled human interferon-alpha2 (huIFN-alpha2) to Madin-Darby bovine kidney cells previously exposed to subsaturating concentrations of IFN-alpha showed approximately a 50% decrease in the number of cell surface receptors and no change in the apparent dissociation constant, Kd, compared with cells not exposed to interferon. The steady state equations describing the interaction of polypeptide ligands with cell surface receptors under physiological conditions (Wiley, H.S., and Cunningham, D.D. (1981) Cell 25, 433-440) have allowed us to determine, under steady state conditions, the rate of insertion of receptors into the cell membrane, the endocytic rate constant of occupied receptors, the rate constant of turnover of unoccupied receptors, and the rate of hydrolysis of internalized ligand. Our results indicate that occupied and unoccupied interferon receptors are cleared from the cell surface at approximately the same rate. This suggests that the down-regulation of the huIFN-alpha2 receptor on Madin-Darby bovine kidney cells by huIFN-alpha2 differs from that of several other surface receptors for polypeptide hormones and growth factors analyzed on cultured cells in that the binding of huIFN-alpha2 to its receptor does not increase the rate of receptor endocytosis.

Isolation and properties of L-amino acid oxidase from Ophiophagus hannah venom

This paper reports the isolation and some properties of L-amino acid oxidase from Ophiophagus hannah venom. The differences between L-amino acid oxidase from Ophiophagus hannah and that from other sources in specific activity, properties and the spectrum of isozymes are noticeable. The result of electrophoresis on polyacrylamide gel shows that this purified enzyme is homogenous. The molecular weight determined by gradient polyacrylamide gel slab (4--30%) is around 15 X 10(4) dalton. The molecular weight of the subunit determined by SDS gradient gel electrophoresis (4--30%) is around 7.3 X 10(4) dalton. Therefore, this enzyme is composed of two subunits. The absorption spectrum reveals that there are two FADs in each molecule. The optimum pH of enzymic reaction is around 8.7--9.0 when L-leucine is used as substrate. The inhibition of the products is noticeable when substrate concentration goes beyond 3mM. This enzyme is heat stable and its activity would not decrease obviously after heating at 55 degrees C for 40 min. A linear relationship between enzyme concentration and reaction rate was noticed when enzyme concentration was below 5.7 micrograms/ml.

Cardiovascular effects of therapeutic doses of tricyclic antidepressants: importance of blood level monitoring

The cardiovascular effects of therapeutic doses of tricyclic antidepressants are reviewed and their clinical significance discussed. At standard therapeutic doses these antidepressant drugs produced small changes in heart rate and several intervals of the EKG in some patients, but clinically significant effects on the EKG are usually seen only in patients with high blood levels of the drugs; these high plasma levels are often above those needed for therapeutic antidepressant effects. In contrast, the orthostatic hypotension induced by antidepressants usually occurs at dosages and blood levels within the therapeutic range, and, therefore, this side-effect may be of greater clinical significance in standard clinical treatment with antidepressants. A review of recent studies suggest that adequate doses of antidepressants may be used safely in geriatric depressed patients and in many patients with stable preexisting cardiac disease. However, more frequent monitoring of plasma levels of antidepressants and EKGs may be particularly important in these groups of patients.

Detection of viral proteins in mouse mammary tumors by immunoperoxidase staining of paraffin sections

An indirect immunoperoxidase method is described, which can readily detect viral antigens in paraffin sections of primary, transplanted, and metastatic mammary tumors of mice. In addition to having the obvious advantage of not being limited to fresh specimens, immunoperoxidase staining of paraffin sections proved to be superior in many respects when compared with immunofluorescence and frozen sections. Immunoperoxidase staining of paraffin sections is permanent and provides the kind of histological detail required for precise cytological identification and localization with light microscopy. All of 25 tumors and 4 metastatic lesions showed evidence of glycoprotein gp52 as well as other mouse mammary tumor viral antigens. The pattern and intensity of the stain were related to the degree of histologic differentiation of the tumor. Wide variations in expression of viral antigens by individual malignant cells were observed within the same tumor.