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Biomedical subjects

M Strand

Publications and source records attributed to M Strand.

At least 109 records · Page 6Linked to original sources
PubMed1983

Lung-stage expression of a major schistosome surface antigen.

The topographical expression of a glycoprotein of 180,000 molecular weight on the surface of lung-stage Schistosoma mansoni schistosomula was determined by immunofluorescence microscopy using a monoclonal antibody. Postfixation treatment with graded ethanols enhanced specific immunofluorescent staining of adult worms, and was required for detection of the antigen on the surfaces of lung-stage schistosomula. The epitope recognized by the monoclonal antibody was also present on the surfaces of adult Schistosoma haematobium, but not on those of Schistosoma japonicum.

Animals↗
PubMed1983

Kinetic and catabolic considerations of monoclonal antibody targeting in erythroleukemic mice.

The parameters affecting the use of tumor-specific monoclonal antibodies for diagnostic imaging and tumor cell targeting and therapy were quantitatively examined in a murine erythroleukemia model system. Normal and tumor-bearing leukemic BALB/c mice were given injections of 125I-, 131I-, or 111In-labeled specific and control immunoglobulins. At various times after injection, gamma camera images were obtained, and targeting to whole organs and to isolated cells was measured. The following observations were made: (a) tumor-specific monoclonal antibodies rapidly targeted to tumor cells (within hr); (b) the ratio of binding to tumor cells as compared to normal cells was highest (63.7 +/- 7.6) at the earliest times (6 hr after injection); (c) specific targeting was reflected by 20-fold shorter half-lives of antibody in the blood of tumor-bearing mice; (d) bound antibody was rapidly catabolized, and the radiolabel was cleared from the target (within hr) and appeared in organs metabolizing or excreting the radioisotope; (e) optimal images of tumors, using either 131I- or 111In-diethylenetriaminepentaacetic acid-labeled antibodies, were obtained early after extravascular distribution of the antibody because of the rapid targeting, clearance, and excretion or metabolism of isotope; and (f) changing the immunoglobulin isotype class or fragment had large effects on the half-life of the antibody but did not improve cell targeting uptake ratios or image contrast or alleviate the problem of specific catabolism. These results suggest (a) that diagnostic imaging should be obtained immediately after extravascular distribution of the antibody using short-lived isotopes and (b) that tumoricidal agents coupled to antibodies must act quickly upon targeting. In our system, the radiometal chelate-conjugated monoclonal antibodies appear to be the most versatile and effective at satisfying these criteria.

Animals↗
PubMed1983

Identification of species-specific and gender-specific proteins and glycoproteins of three human schistosomes.

Species-specific and gender-specific polypeptides of Schistosoma haematobium, Schistosoma japonicum, and Schistosoma mansoni have been identified. Proteins of these schistosomes were metabolically labeled in vitro with 35S-methionine and their total proteins, concanavalin-A binding glycoproteins, released (shed or secreted) proteins, and released glycoproteins compared by two-dimensional polyacrylamide electrophoresis. Many of the released proteins were glycosylated, and most of the synthesized glycoproteins were released. The most striking gender-specific and species-specific differences were observed in the released glycoproteins. These results provide a basis for investigating the molecular evolution of schistosomes, the occurrence of dioecy in the schistosomatidae , and for the development of improved serodiagnostic reagents.

Animals↗
PubMed1982

Tumor imaging with radioactive metal chelates conjugated to monoclonal antibodies.

High-resolution gamma camera images of mouse erythroid tumors were obtained by use of leukemia cell-specific monoclonal antibodies labeled with bifunctional radioactive metal chelates. Small tumors (200 to 300 milligrams) were visible without subtraction or enhancement 1 to 5 hours after injection of antibody. Chelate-derivitized monoclonal antibodies permit targeting of a broad spectrum of radioisotopes, including those that are optimum for agamma for gamma camera imaging or positron tomography, as well as those that are tumoricidal.

Animals↗
PubMed1982

Leukemic cell targeting and therapy by monoclonal antibody in a mouse model system.

A monoclonal antibody prepared against the Rauscher virus envelope glycoprotein with a molecular weight of 70,000 targeted to neoplastic cells and cured the Rauscher leukemia virus-induced erythroleukemia in BALB/c mice. This antibody, 103A, specifically reacted with the Rauscher and Friend erythroleukemia viruses and erythroleukemic cells but did not react with other murine ecotropic or xenotropic viruses or feline leukemia virus or with normal spleen cells, thymocytes, or fibroblasts, as measured by radioimmunoassays. P3, a control antibody of the same immunoglobulin G1 subclass, did not bind to any of these cells or viruses. This specificity was maintained in vivo. 125I-Labelled 103A injected into mice targeted to leukemic spleen cells but not to normal cells. Mean uptake ratios of binding to leukemic over normal spleen cells ranged from greater than 70 at 7 hr after injection to less than 10 at 40 hr later. The control antibody showed no binding in vivo. A single small dose of 103A was able to cure leukemic mice as assayed by spleen focus formation on Day 8 or splenomegaly on Day 20. The 50% effective dose was 1.5 micrograms when injected 72 hr after onset of leukemia. The therapeutic potencies of drugs, toxins, and cytotoxic radioisotopes conjugated to antibodies can be quantitatively compared using the established dose-response curve. Such quantitative comparisons showed that 131-labeled 103A immunoglobulin G was no more potent than unlabeled 103A immunoglobulin G in this system.

Animals↗
PubMed1981

A brain membrane protein similar to the rat src gene product.

We report the purification to homogeneity of a 20,000-dalton, transformation-related, rat cell membrane protein. This protein, p20, was originally identified in preparations of a defective woolly monkey leukemia virus pseudotype of Kirsten sarcoma virus. The chromatographically purified p20 was an acidic hydrophobic protein, capable of specifically binding GTP (dissociation constant = 15 microM). This nucleotide binding property and other previously reported characteristics were similar to properties ascribed to the Harvey sarcoma virus src gene product. p20 also appeared similar to this src gene product when immunoprecipitates of both proteins were directly compared by one- and two-dimensional NaDodSO4 gel electrophoreses. However, the proteins were not identical, because their tryptic maps differed. Using a competition radioimmunoassay, we have measured the concentration of p20 in cells, viruses, and rat tissues: p20 was not encoded by rat sarcoma viruses because it was increased only slightly after Kirsten sarcoma virus transformation of rat cells and was not increased in nonrat cells transformed by the Kirsten or Harvey sarcoma virus. Remarkably, of 10 rat tissues examined, p20 was found predominantly in brain, specifically in the membranes.

Animals↗
PubMed1981

55,000-dalton, retrovirus-associated, cell membrane glycoprotein: purification and quantitative measurements of expression in viruses, cells, and tissues.

We have purified to homogeneity and characterized a 55,000-dalton rat cell membrane glycoprotein, gp55. This protein was originally identified in preparations of a defective pseudotype of the Kirsten sarcoma virus and shown to be present in several rodent retrovirus particles. The gp55 was purified from this defective virus by concanavalin A and heparin affinity chromatography, as well as by preparative sodium dodecyl sulfate-gel electrophoresis. Both preparations displayed similar purity and antigenic characteristics. The 125I-labeled gp55 was precipitated by antisera against rodent retroviruses, but not by monospecific antisera against purified type C virus structural proteins, thus indicating that gp55 was retrovirus associated, but unrelated to known retrovirus structural proteins. Competition radioimmunoassay with an anti-rat virus serum which recognized rodent group-specific antigens on gp55 indicated: the presence of gp55 antigens in 15 rodent cell lines, but not 10 nonrodent cell lines; no effect of viral infection or cell transformation on the amount of gp55 expressed; up to 100-fold increases in the concentration of the gp55 antigens in nine rodent retroviruses, but not in five nonrodent viruses, as compared to cells; the presence of gp55 in rodent sera, especially of the NZB mouse, where anti-gp55 antibody was also detected; a lymphoid and epithelial tissue distribution of gp55 in rats and mice. Additional competition radioimmunoassays with a broad-reacting antivirus serum also detected the presence of gp55 in nonrodent, mink, and human cells and thus distinguished rat type, rodent group, and interspecies antigenic determinants on gp55. In conclusion, gp55 is a cell membrane glycoprotein associated in high concentration with retroviruses.

Animals↗
PubMed1980

Transformation-related antigens identified by monoclonal antibodies.

Tumor-cell proteins that were antigenic in a syngeneic animal were identified by immunoprecipitation with monoclonal antibodies. Spleen cells of BALB/c mice immunized with plasma membranes of Kirsten RNA sarcoma virus-transformed BALB/3T3 cells were fused with NS-1 myeloma cells. Antibodies secreted into the culture fluid from these hybridomas were distinguished by their reactivity against proteins of different target cells. A total of 191 cultures were established; 143 produced antibodies that bound to BALB/3T3 cells transformed by the RNA sarcoma virus, of which antibodies from 82 bound to BALB/3T3 transformed with simian virus 40, and antibodies from 56 bound to BALB/3T3 cells. Thus, more than 50% of the cultures produced antibodies that possibly were specific to antigens of the transformed cell. Twenty different hybridomas have been cloned, and antibodies, from eight of these were found to immunoprecipitate five different proteins. A protein of approximately 32,000 daltons was precipitated from BALB/3T3 cells transformed by the RNA sarcoma virus, simian virus 40, or methylcholanthrene but not from untransformed BALB/3T3 cells. A protein of about 300,000 daltons was precipitated from all four cell lines; precipitation was enhanced in the viral transformed cells. Proteins of approximately 57,000, 54,000, and 8500 daltons were immunoprecipitated from all four cell lines.

Animals↗
PubMed1979

Identification of a mouse gene required for binding of Rauscher MuLV envelope gp70.

Mouse chromosome segregating somatic cell hybrids were established between a mouse thymic leukemai cell line (GRSL) and Chinese hamster E36 cells. The GRSL cells specifically bound purified Rauscher leukemia virus gp70 while the E36 cells exhibited no binding. The hybrids selectively bound Ruascher gp70 depending on the presence of a mouse cellular gene for the ecotropic murine luekemia gp70 receptor. A syntenic relationship was observed between the DIP-3 chromosome marker (on chromosome 5) and the gp70 receptor in primary clones and subclones of these hybrids; this was confirmed by chromosome analysis. The involvement of H-2 in the binding of Rauscher MuLV gp70 could be ruled out, because discordancies of the receptor presence and H-2 absence as well as of the receptor absence and H-2 presence type could be observed. Our results indicate that the Rec-1 (replication ecotropic MuLV) gene of Gazdar et al. (4) may well be the receptor gene for the ecotropic murine leukemia virus.

Animals↗
PubMed1979

Interactions between cellular membrane receptors and oncovirus envelope glycoprotein: influence of enzymes and protein-modifying reagents on receptors.

Binding of purified envelope glycoprotein (gp69/71) of Rauscher murine type C oncovirus to cellular membrane receptors has been analyzed with reaction systems using intact cells or membranes of disrupted cells. The reaction was highly specific; only cells permissive to infection by Rauscher virus bound the 125I-labeled viral glycoprotein. The specificity of binding was also demonstrated with respect to virus interference; cells productively infected with murine ecotropic type C virus failed to bind the virus envelope glycoprotein, whereas permissive cells infected with murine xenotropic virus continued to bind the Rauscher ecotropic virus glycoprotein. The reaction required the presence of Ca2+ or Mn2+ and was rapid and reversible. Studies of the enzymatic digestion of membranes suggested that the receptor is a protein which requires lipid either for its activity or for the integrity in the membrane. Receptor binding was greatly reduced by modification of histidine, tyrosine, and tryptophan residues.

2-Hydroxy-5-nitrobenzyl Bromide↗