Elevated epidermal growth factor receptor binding in plutonium-induced lung tumors from dogs

The objective of this study is to examine and characterize epidermal growth factor receptor (EGF-R) binding in inhaled plutonium-induced canine lung-tumor tissue and to compare it with that in normal canine lung tissue. Crude membrane preparations from normal and lung-tumor tissue from beagle dogs were examined in a radioreceptor assay, using 125I-labeled epidermal growth factor (EGF) as a ligand. Specific EGF receptor binding was determined in the presence of excess unlabeled EGF. We have examined EGF receptor binding in eight lung-tumor samples obtained from six dogs. Epidermal growth factor receptor binding was significantly greater in lung-tumor samples (31.38%) compared with that in normal lung tissue (3.76%). Scatchard plot analysis from the displacement assay revealed that there was no statistical difference in the binding affinity but significantly higher concentration of EGF-R sites in the lung-tumor tissue (619 fmol/mg) than in normal lung tissue (53 fmol/mg). The increase in EGF-R number in plutonium-induced dog lung tumors does not seem to correlate with increase in the initial lung burden exposure to plutonium. Our results demonstrate that there is a significant increase in EGF-R binding in inhaled plutonium-induced dog lung tumors.     

Position and orientation in the metaphase equator of an interchange quadrivalent of hybrid rye

The position and orientation of an interchange quadrivalent in flattened lateral views of metaphase I were studied in pollen mother cells of hybrid rye. Five quadrivalent types showed three positional distributions in the equator, these distributions having elements both similar to and very different from those found previously for an interchange quadrivalent of Allium triquetrum.     

Target-sensitive immunoliposomes: preparation and characterization

A novel target-sensitive immunoliposome was prepared and characterized. In this design, target-specific binding of antibody-coated liposomes was sufficient to induce bilayer destabilization, resulting in a site-specific release of liposome contents. Unilamellar liposomes were prepared by using a small quantity of palmitoyl-immunoglobulin G (pIgG) to stabilize the bilayer phase of the unsaturated dioleoylphosphatidylethanolamine (PE) which by itself does not form stable liposomes. A mouse monoclonal IgG antibody to the glycoprotein D of Herpes simplex virus (HSV) and PE were used in this study. A minimal coupling stoichiometry of 2.2 palmitic acids per IgG was essential for the stabilization activity of pIgG. In addition, the minimal pIgG to PE molar ratio for stable liposomes was 2.5 X 10(-4). PE immunoliposomes bound with HSV-infected mouse L929 cells with an apparent Kd of 1.00 X 10(-8) M which was approximately the same as that of the native antibody. When 50 mM calcein was encapsulated in the PE immunoliposomes as an aqueous marker, binding of the liposomes to HSV-infected cells resulted in a cell concentration dependent lysis of the liposomes as detected by the release of the encapsulated calcein. Neither uninfected nor Sendai virus infected cells caused a significant amount of calcein release. Therefore, the release of calcein from PE immunoliposomes was target specific. Dioleoylphosphatidylcholine immunoliposomes were not lysed upon contact with infected cells under the same conditions, indicating that PE was essential for the target-specific liposome destabilization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Failure of gallamine and pancuronium to inhibit selectively (-)-[3H]quinuclidinyl benzilate binding in guinea-pig atria

Binding of (-)-[3H]quinuclidinyl benzilate (QNB) to muscarinic sites in guinea-pig atrial and ileal longitudinal muscle homogenates showed the presence of a single population of binding sites in atria (KD = 41 (32-53) (95% confidence limits) pM; Bmax = 0.225 +/- 0.02 pmol/mg protein (3)) and two binding sites in the ileum (KD = 20.9 (8.8-49) pM and 11.3 nM; Bmax = 0.436 +/- 0.09 and 11.85 +/- 2.63 pmol/mg protein (4), respectively). Atropine, gallamine, and pancuronium displaced (-)-[3H]QNB binding from the high affinity binding sites in the two tissues in a dose-dependent manner with -log Ki values of 8.6, 6.4, and 6.9, respectively, in atria and 8.7, 6.8, and 6.9, respectively, in ileal longitudinal muscle. The lack of selectivity of gallamine and pancuronium in binding experiments differed from results obtained in isolated tissue experiments where these antagonists showed a marked difference in their ability to antagonize cholinomimetics in the two tissues. In addition, the Ki values for gallamine and pancuronium in ileal homogenates were ca. 130- and 16-fold lower, respectively, than their KB values determined from isolated tissue experiments. Attempts to correlate data from binding experiments and isolated tissue experiments using combinations of antagonists led to variable results attributed to differences in the rates of dissociation of the antagonists from muscarinic receptors. It is concluded that the interaction of gallamine or pancuronium with agonists or antagonists at muscarinic receptors is not a simple bimolecular interaction.     

Altered gene products are associated with activation of cellular rasK genes in human lung and colon carcinomas

Two lung and two colon carcinoma cell lines of human origin, which contained the same activated ras^K transforming gene, expressed abnormal species of p21 that were distinct from the p21 proteins expressed in normal human cells and other human carcinomas. The abnormal species of p21 expressed by three of these cell lines were indistinguishable from each other, but differed from the abnormal p21 expressed by one lung carcinoma cell line. NIH cells transformed by DNAs of these carcinomas expressed the same abnormal p21 species, indicating that these abnormal proteins were encoded by the activated ras^K genes detected by transfection. These results indicate that transforming activity of ras^K genes in human lung and colon carcinoma cell lines is activated by mutations which alter the structure of their gene products, and that activation of ras^K genes can result from different molecular alterations in different individual neoplasms.     

Isolation of two pure polysaccharides from the hemicellulose of slash pine (Pinus elliottii)

Two pure, acidic polysaccharides have been isolated from the hemicellulose of slash pine in yields of 1–2% and 4–5%. Their properties are compared, and the structure of one of them has been investigated by methylation analysis. The results indicate that the glycan is a β-D-(1→4)-linked xylan chain with many branch points. 4-O-Methyl-D-glucopyranosyluronic acid, L-arabinofuranose, and D-xylopyranose residues occur as non-reducing end groups. The uronic acid occurs as single-unit attachments to the main chain. Some of the D-xylose residues in the polysaccharide are doubly branched. The total hemicellulose components of the wood probably represent a complex mixture of chemical types, from which the two pure fractions described above may be separated fortuitously by careful, fractional precipitation.