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D Horn

Publications and source records attributed to D Horn.

At least 109 records · Page 6Linked to original sources
PubMed1987

Phosphorylated fructose-1,6-bisphosphatase dephosphorylating protein phosphatase from Saccharomyces cerevisiae.

Phosphorylation of fructose-1,6-bisphosphatase with cyclic AMP-dependent protein kinase from yeast is accompanied by a 50% decrease in the catalytic activity (Pohlig, G. and Holzer, H. (1985) J. Biol. Chem. 260, 13818-13823). Using reactivation of phoshorylated fructose-1,6-bisphosphatase as assay, a protein phosphatase was about 2,000-fold purified to electrophoretic homogeneity from Saccharomyces cerevisiae. Upon incubation with phosphorylated fructose-1,6-bisphosphatase the purified protein phosphatase not only reverses the 50% inactivation caused by phosphorylation, but also the previously observed change in the pH optimum and in the ratio of activity with Mg2+ or Mn2+. The phosphatase is strongly inhibited by heparin and fluoride. L-Carnitine, orthophosphate, pyrophosphate, and succinate inhibit to 50% at concentrations from 1 to 10 mM. The molecular mass of the native phosphatase was found to be 180,000 Da. Sodium dodecyl sulfate-gel electrophoresis suggested four subunits with a molecular mass of 45,000 Da each. Half-maximal activity was observed with 5 mM Mg2+ or Mn2+, the pH optimum of activity was found at pH 7. Using polyclonal antibodies, disappearance of 32P-labeled fructose-1,6-bisphosphatase and concomitant liberation of the expected amount of inorganic [32P] phosphate was demonstrated.

Electrophoresis, Polyacrylamide Gel↗
PubMed1986

Identification of a novel serum protein secreted by lung carcinoma cells.

The murine anti-human lung tumor monoclonal antibody L3 recognizes antigens found both in the medium of cultured carcinoma cells and in normal human serum. Sequential immunoprecipitation experiments indicate that the L3 antigen is also recognized by a previously described monoclonal antibody directed against a melanoma-associated antigen [Natali, P. G., Wilson, B. S., Imai, K., Bigotti, A., & Ferrone, S. (1982) Cancer Res. 42, 583-589]. This antibody precipitated a Mr 76000 glycoprotein from metabolically labeled extracts of the lung carcinoma cell line Calu-1 and a Mr 94 000 glycoprotein from labeled culture medium. Pulse-chase experiments suggested a precursor-product relationship between these molecules. Analysis of glycosidase sensitivities of the two forms indicated that maturation of carbohydrate side chains correlated with the apparent increase in molecular weights. L3 antigenic activity, measured in a competitive radiometric cell binding assay, was purified more than 90-fold from serum-free medium of Calu-1 cells and more than 3000-fold from normal human serum. The major immunoreactive components purified from culture medium and serum were identical with respect to apparent molecular weight, electrophoretic mobility, pI, glycosidase sensitivity, and V8 protease fingerprints. In addition, the sequence of the amino-terminal 16 N-terminal amino acid residues of the major immunoreactive species from both sources was identical. The properties of the L3 antigen did not correspond to those of any known protein, suggesting that this serum protein has not been previously characterized.

Amino Acid Sequence↗
PubMed1986

Interexaminer reliability of the optic cup to disc ratio assessment.

Previous controlled reliability studies of cup to disc (C/D) ratio estimations may have been biased by lack of criteria for cup determination, small sample size; and/or large interval grouping of collected data. In our study four examiners independently estimated the C/D ratios of 40 patients by direct ophthalmoscopy using a contour criterion for cup determination. Results indicated that 75% of the estimate pairs differed by 0.10 or less. Fewer than 14% of the estimate pairs differed by 0.2 or greater. The results of the study suggest that when examiners use a specified criterion of contour cupping, interexaminer assessment of the C/D ratio estimation is clinically and statistically reliable.

Adolescent↗
PubMed1986

Patterns of bilirubin staining in nonhemolytic kernicterus.

Patterns of bilirubin staining were studied in nine infants with kernicterus related to nonhemolytic hyperbilirubinemia, all weighing less than 1200 g, and nine matched controls. Three staining patterns were disclosed: a localized pattern in the central nervous system of kernicteric infants, with only the thalamus staining significantly often; staining, in extraneural tissues (adrenal, myocardial, renal, and colonic mucosa) only in kernicteric infants, despite similar bilirubin levels in both groups; and yellow staining of the alveolar hyaline membranes as a function of survival duration in both groups. Bilirubin staining of tissue is apparently a generalized phenomenon, most recognized in the central nervous system as kernicterus. Failure to maintain the impermeability of the cell membrane coupled with regional differences in blood flow would best explain bilirubin distribution. In contrast, the degree of bilirubin staining of alveolar hyaline membranes is time related in kernicteric and control infants.

Bilirubin↗
PubMed1986

Elevated levels of a high molecular weight antigen detected by antibody W1 in sera from breast cancer patients.

A novel screening assay was used to test 13 previously described antibreast cancer antibodies for those which recognize antigens elevated in serum of breast cancer patients. Binding of three of these antibodies to breast or lung carcinoma cells was inhibited to a significantly greater extent by tumor patient serum than by normal serum, suggesting that the antigens might be useful serum markers. Two of these antibodies, W1 and W9, were shown to recognize nonoverlapping epitopes on a high molecular weight molecule(s) purified from serum from breast cancer patients. A sensitive double determinant immunoassay was developed to measure W1 antigen levels in sera from a total of 389 cancer patients and controls. Forty seven % (37 of 79) of individuals having breast cancer showed elevated serum levels of the W1 antigen, whereas only 4% (1 of 25) of normal controls and 2% (1 of 47) of patients hospitalized for nonmalignant disorders showed elevated levels. These differences were statistically significant (P less than 0.001). The percentage of breast cancer patients showing elevated serum levels was greater for individuals with metastatic disease. Statistically significant numbers of lung, ovarian, and prostate, but not colon, cancer patients also had elevated serum levels of the W1 antigen. These data suggest that measurement of the W1 antigen in serum might provide clinically useful information on the course of metastatic breast and other cancers.

Antibodies, Monoclonal↗
PubMed1986

Heritable variation in expression of multiple tumor associated epitopes on a high molecular weight mucin-like antigen.

Monoclonal antibodies with specificity for mucin-like antigens have shown great promise for the diagnosis and therapy of human cancer. Heterogeneity in the expression of mucin-like antigens by tumor and normal cells has been noted in several previous studies. An understanding of the nature of this heterogeneity has important implications for the diagnostic and therapeutic usefulness of antibodies to mucin-like antigens. We have studied the mechanism of variability in expression of epitopes on a mucin-like antigen defined by monoclonal antibodies W1, W5, and W9 in the lung carcinoma cell line, Calu-1. Using the fluorescence activated cell sorter and clonal analysis, we have demonstrated that intercellular variability in mucin antigen expression by Calu-1 cells can be explained in part by heritable variation in the tumor cell population. Clonal cell lines were isolated which differ greatly in levels of epitopes for all three mucin directed antibodies. Levels of all three epitopes showed significant variation between different clonal lines but in general were coordinately regulated. Differences in epitope expression between two lines studied in detail could be attributed to a dramatic difference in expression of a high molecular weight mucin-like glycoprotein. In immunoblotting experiments the binding of all three antibodies to this glycoprotein was affected by sodium periodate and/or neuraminidase treatment, suggesting that the antibodies recognize carbohydrate epitopes. Thus, heterogeneity in expression of mucin-like glycoprotein antigens can result from heritable variations which affect expression of multiple carbohydrate epitopes.

Antibodies, Monoclonal↗
PubMed1986

Monoclonal mouse antibodies raised against human lung carcinoma.

We have evaluated approximately 10,000 monoclonal antibodies (MoAb) resulting from 25 hybridizations of spleen cells from mice immunized with cells from human non-small cell lung carcinoma or fetal lung. The spleen cells were hybridized with NS-1 myeloma cells, and the resulting hybridomas were screened for production of MoAb to non-small cell lung carcinoma by binding assays with either cell extracts or cells growing in culture, followed by immunohistology on frozen sections. Fourteen MoAb had relative specificity for non-small cell lung carcinoma versus normal tissues. Three of these MoAb (L3, L6, L17) also reacted with most carcinomas of the breast and colon, and two MoAb (L20 and L22) reacted with the four samples of small cell lung carcinoma tested. No MoAb defined an antigen of absolute tumor specificity, and no MoAb reacted substantially more with adenocarcinoma than squamous cell carcinoma of the lung (or vice versa). Five MoAb were Ig G1, two were Ig G2a, and the remaining seven were Ig M. Seven MoAb (L5, L6, L15, L17, L20, L22, L23) could bind to the cell surface. Three MoAb (L6, L15, L17) defined carbohydrate antigens, and three (L3, L5, L20) were to protein antigens, while the antigens to which the remaining MoAb are directed have not been identified. Six MoAb could bind to tumor cells in Carnoy-fixed paraffin-embedded sections. An intercellular variability in antigen expression was detected with all 14 MoAb. At least two of the MoAb, L6 and L20, are good candidates for preclinical testing in view of their high level of tumor selectivity, as shown by both immunohistology and binding assays with living cells.

Animals↗