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G B Price

Publications and source records attributed to G B Price.

At least 55 records · Page 3Linked to original sources
PubMed1990

The dynamic distribution and quantification of DNA cruciforms in eukaryotic nuclei.

Cruciforms have been suggested as potential recognition structures at or near origins of DNA replication in eukaryotic cells. Monoclonal antibodies specific for cruciforms have been produced. The antibody binds to structural determinants at the base of the cruciform stem, the "elbow." Labeling of nuclei with anti-cruciform antibodies produces a nonuniform pattern of fluorescence in cells arrested at the G1/S boundary. This pattern of fluorescence changes when these cells are released from synchrony. Using fluorescence flow cytometry to quantify the number of DNA cruciform structures in cells throughout the cell cycle, we observed two major populations of nuclei with different numbers of cruciforms; the modal number of cruciforms in these populations was 0.6 x 10(5) and 3 x 10(5) cruciforms per nucleus. Synchronized cells (doubly arrested by serum starvation and aphidicolin) displayed a biphasic distribution of the number of cruciforms over the first 6 h after release from synchrony with maxima at 0 and 4 h after release.

Animals↗
PubMed1989

Characterization of the binding specificity of two anticruciform DNA monoclonal antibodies.

Two monoclonal antibodies (2D3 and 4B4) have been raised against a stable cruciform DNA structure containing the 27-base pair palindrome of the SV40 origin of replication on one strand and an unrelated 26-base pair palindrome on the complementary strand (pRGM 21 x pRGM 29) and have been shown to recognize conformational determinants specific to cruciform DNA structures (Frappier, L., Price, G.B., Martin, R. G., and Zannis-Hadjopoulos, M. (1987) J. Mol. Biol. 193, 751-758). To define the region(s) of the cruciform that is recognized by these antibodies, we examined the ability of 2D3 and 4B4 to protect the single-stranded tips of the loops or the four-way junctions at the base of the stem of stable cruciform molecules against cleavage by mung bean nuclease or T7 endonuclease 3, respectively. Both antibodies were found to protect two of the four elbow-like structures at the base of the cruciform from T7 endonuclease 3 cleavage, but not the tips of the cruciform arms from mung bean nuclease cleavage. Also, predigestion of the cruciform with mung bean nuclease did not affect the binding of either antibody. In addition, 2D3 bound to a cruciform and a T-shaped structure involving the palindromic sequence at the cloning site of pUC7, which is completely unrelated in sequence to the palindrome of pRGM 21 x pRGM 29, and protected the base of these stem-loop structures against cleavage by T4 endonuclease VII. These results indicate that 2D3 and 4B4 bind at or near the base of the cruciform molecules and that, at least for 2D3, binding is independent of DNA sequence.

Antibodies, Monoclonal↗
PubMed1988

Effect of anti-cruciform DNA monoclonal antibodies on DNA replication.

To study the possible involvement of DNA cruciforms in the initiation of DNA replication, we used two monoclonal antibodies, 2D3 and 4B4, with anti-cruciform DNA specificity. Synchronized CV-1 cells were released into S phase for hourly intervals up to 6 h and permeabilized in the presence of monoclonal antibodies, under conditions that allow limited DNA replication. Exposure of the permeabilized cells to 2D3 or 4B4 resulted in a 2- to 6-fold enhancement of incorporation of labeled precursor nucleotide over the 6 h period. Approximately 50% of the enhanced synthesis was sensitive to aphidicolin, and the enhancing effect of 2D3 was abolished by absorption with immunobead anti-mouse immunoglobulin. Dot-blot hybridization analyses of DNA isolated from anti-cruciform antibody treatment groups showed a similar 2- to 11-fold increase in the relative copy number of low copy probes. In contrast, exposure of the permeabilized cells to a monoclonal antibody directed against Z-DNA and B-DNA had no significant effect on DNA synthesis. The results suggest that cruciforms are present in replicating DNA and that they are recognized and stabilized by the monoclonal antibodies.

Animals↗
PubMed1987

Monoclonal antibodies to cruciform DNA structures.

Two monoclonal antibodies, 2D3 and 4B4, have been raised against a cruciform structure in a heteroduplex DNA molecule. Antibody binding to DNA fragments was determined by a radioimmunoassay in which DNA--antibody complexes were separated from unbound DNA by acrylamide gel electrophoresis. These antibodies seem to recognize conformational determinants specific to cruciform structures. 2D3 and 4B4 antibodies do not bind to linear double-stranded homoduplex DNA fragments, linear single-stranded DNA or single-stranded simian virus 40 DNA containing a stem--loop structure, but do bind to the original cruciform and to a different cruciform with one shortened arm. 2D3 also bound to a T-shaped double-stranded DNA molecule, while 4B4 binding to this structure was weak. The monoclonal antibodies 2D3 and 4B4 were found to be immunoglobulin G1 and immunoglobulin M, respectively.

Animals↗
PubMed1987

Cellular heterogeneity in normal and neoplastic human urothelium: a study using murine monoclonal antibodies.

To assist in the description of the cellular heterogeneity present in normal and neoplastic urothelium, a panel of monoclonal antibodies (MoAbs) was raised against human transitional cell carcinoma (TCC) of the urinary bladder. All immunizations were carried out using whole cells and membrane preparations from well differentiated human TCCs. Two fusions produced 145 hybridomas. Following primary screening by ELISA and secondary screening with immunohistochemistry, three useful antibodies were identified. MoAb 35.48 binds to all cell layers of the normal urothelium and well differentiated tumours, but not to the majority of poorly differentiated tumours. MoAb 21.48 binds preferentially to the basal cell layer of normal urothelium and to some well differentiated papillary TCCs, but poorly differentiated tumours exhibit diffusely positive staining. MoAb 21.48 also shows cross-reactivity with basal cell layers of other epithelia. MoAb 5.48 binds preferentially to the superficial cell layers of normal urothelium and well differentiated TCCs, but exhibits less binding in poorly differentiated tumours with loss of the preferential superficial staining. Quantitative flow cytometric studies indicate that MoAb 5.48 binds to a cell-surface antigen which is present on significantly fewer cells of poorly differentiated tumours than on either normal urothelium (P less than 0.05), or well differentiated tumours (P = 0.05).

Animals↗
PubMed1986

Studies on HSAG, a middle repetitive family of genetic elements which elicit a leukemia-related cellular surface antigen.

HSAG is a family of genetic elements capable of eliciting, in transfected cells, a cellular surface antigen which is correlated with human chronic lymphocytic leukemia (CLL). Its prototype member, HSAG-1, was cloned as a 3.4 kb insert and contains numerous Alu-related elements, including its left hand 1.4 kb antigen-eliciting end. These elements are present in mammalian cells with copy numbers varying from 7,000 to 200,000 per haploid genome, depending on how closely their sequence conforms to the Alu consensus sequence. They are present in the configuration found in HSAG-1, a 3.4 kb EcoRI fragment which is part of a larger unit of at least 12.7 kb, at a frequency of 20-50 per haploid genome, and dispersed around the genome. A second family member, HSAG-2, isolated using a functional assay, was cloned as a 9.5 kb insert and contained a 1.5 kb antigen-eliciting left hand end. As in HSAG-1, the antigen-eliciting portion of the insert also contained Alu-like elements, unlike most of the remainder of the insert. A number of HSAG family members were cloned from a library of human CLL genomic DNA by sequence homology with the antigen-eliciting portion of HSAG-1. Most of these members were also shown to be capable of eliciting antigen. Their only sequence similarity with HSAG-1 appeared to be in their content of numerous Alu-like elements. The evidence thus supports the view that the HSAG functional family consists of clusters of Alu-like elements.

Animals↗
PubMed1986

The structure of HSAG-1, a middle repetitive genetic element which elicits a leukemia-related cellular surface antigen.

HSAG-1 is a cloned member of a heterogeneous middle repetitive family of genetic elements which is capable of eliciting a leukemia-related surface antigen detected with a monoclonal antibody after DNA transformation of mouse cells. HSAG-1 was originally isolated from a Chinese hamster-human leukemia hybrid cell gene library both by sib-selection for antigen producing activity and by hybridization with labelled human genomic human DNA. We show here that the human labelled site is at the right hand end of the insert, while the antigen-eliciting portion is included in a 1450 bp fragment at the left hand end of the insert. We also present the complete nucleotide sequence of the 3369 bp insert. The sequence contains 12 elements which bear a significant resemblance to accepted consensus sequences for Alu repetitive elements. The right hand end contains adjacent elements with close sequence similarity to portions of the human and hamster type I and type II Alu consensus sequences. All of the other Alu-related elements have diverged relative to the Alu consensus sequences by additions, long deletions and substitutions. The left hand portion of the insert which has the antigen-producing activity contains four of these diverged elements representing a relatively high proportion (26%) of the nucleotide sequence. The sequence is thus consistent with our previous observations of a repetitive family with biological function.

Animals↗
PubMed1986

Realtime acquisition, storage, and display of correlated three-parameter flow cytometric data.

A microprocessor-based system which performs realtime correlated acquisition, storage and display of multiparameter (3-parameter) data from a flow cytometer (FACS-III) is presented. List-mode techniques are not employed. The 3-parameter data is collected and correlated, then displayed along with cell-frequency as a realtime 3-parameter colour scattergram, while the experiment is in progress; in addition, correlated and uncorrelated higher-resolution projections of the 3-parameter data are collected and stored. The data projections may also be displayed: as 1-parameter histograms, or as 2-parameter colour or grey-scale scattergrams. Examples of 2- and 3-parameter colour scattergrams are presented. The speed and some characteristics of the realtime acquisition and display software are examined; methods to increase the realtime speed are discussed.

Blood Platelets↗
PubMed1986

Cellular heterogeneity in normal human urothelium: an analysis of optical properties and lectin binding.

Flow cytometry was used to study the optical properties of normal urothelial cells in suspension. Narrow-angle light scatter, which is a function of cell size, defined one major and one minor cell population, and 90 degrees light scatter, a function of intracellular structure, showed three distinct cell populations. These properties were displayed as a 2-dimensional dot plot or "fingerprint" which proved to be characteristic and reproducible from one specimen of urothelium to the next. Cell sorting on the basis of these two parameters demonstrated that the small cells of the basal layer occupy the low narrow angle, low 90 degrees light-scatter region; the giant cells of the superficial layer lie in the high narrow angle, high 90 degrees scatter region; and the pyramidal cells of the intermediate layer lie in an intermediate zone. Studies of tissue sections using the galactose-specific, FITC-conjugated Maclura Pomifera lectin (MPA) demonstrated preferential binding to the superficial layers of intact urothelium. In order to quantify the apparent differences in lectin binding between the superficial and basal layers, urothelial cell suspensions were labeled with FITC-conjugated MPA and studied by flow cytometry. The resolution obtained on the basis of light scatter made it possible to quantify the difference in lectin binding to the three morphologically recognized cell types present in normal urothelium.

Cell Separation↗
PubMed1985

Monoclonal antibody associated with a lymphocyte subpopulation in chronic lymphocytic leukemia.

An IgG monoclonal antibody that detects a subpopulation of lymphocytes found in peripheral blood and bone marrow of patients with CLL and malignant lymphoma is described. The initial immunization used to achieve the resultant monoclonal antibody included the use of cells obtained by DNA transformation of mouse L-cells with the DNA obtained from a morphologically altered somatic cell hybrid between primary human CLL peripheral lymphocytes and a flat-revertant Chinese hamster ovary (CHO) cell line designated GRC+L-73. Hybridomas were thus selected as potentially recognizing antigens associated with the morphological transformation induced by hybridization of CHO cells with lymphocytes from lymphocytic malignancies. One such hybridoma, designated 37-28, was selected for further investigation. The monoclonal antibody produced was IgG (gamma G2a) and detects a subpopulation of lymphocytes present in hematological specimens of some of the lymphocytic malignancies.

Animals↗
PubMed1984

Cells resistant to cytotoxic drugs are recognized by monoclonal antibody.

A monoclonal antibody produced by hybridomas obtained from a mouse immunized with drug-resistant cells recognizes certain hamster and human drug-resistant cell lines but not their drug-sensitive parental lines. Preliminary characterization of the antigen indicates that it is a molecule of approximately 180,000 daltons. This molecule may be the P-glycoprotein previously associated with a drug-resistance permeability barrier (Riordan JR, Ling V: J Biol Chem 254:12701-12705, 1979).

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1984

Alterations in lymphocyte recognition repertoire during ageing. I. Analysis of changes in immune response potential of B lymphocytes from non-immunized aged mice, and the role of accessory cells in the expression of that potential.

The repertoire of specificities recognized by endogenous plaque-forming cells of young or aged mice has been examined, as well as the repertoire of specificities represented by mitogen-activated B cells of those animals. Significant changes occur in both polyclonal endogenous plaque-forming cells and polyclonal B cell responsiveness, as well as reactivity for antigens expressed on bromelain-treated mouse erythrocytes and mouse Ig-coupled sheep erythrocytes. Adoptive transfer experiments suggest that these changes reflect a role for the differentiative environment in the regulation of the B cell recognition repertoire. Additional analysis of changes in antigen-presenting cells in aged mice suggest that alterations in the manner of presentation of environmental antigens in vivo may control the expressed B cell repertoire. Indeed, under experimental conditions it has proven less easy to induce B cell/macrophage restriction (for antigen presentation and induction of antibody formation) in cells of old animals than in cells of younger mice.

Aging↗
PubMed1984

Targeting of liposomes: monoclonal antibodies coupled to phospholipid vesicles provide selective transfer of trapped reagents into cultured cells.

Monoclonal antibodies were incorporated in small unilamellar vesicles by means of ultrasonic irradiation. In order to increase the incorporation efficiency, the immunoglobulins were previously treated at low pH (pH 2), following recent suggestions on the existence of a lipid soluble conformational isomer for serum IgG. The lipid to protein ratios obtained were comparable to the values obtained by other authors using covalent coupling of the antibody to the lipid matrix. Liposome-incorporated monoclonal antibodies directed towards carcinoembryonic antigen (CEA) provided increased transfer of the fluorescent dye carboxyfluorescein from liposomes into cultured human colon carcinoma cells. Another independent experiment was performed on the drug-resistant CHO cell line B30, using a monoclonal antibody to a cell surface marker of drug resistance. Selective liposome mediate drug killing was observed following incubation of the cells with liposomes containing the antitumor agent drug, daunorubicin.

Animals↗
PubMed1984

Altered tumor growth in vivo after immunization of mice with antitumor antibodies.

A comparison has been made between the growth patterns of two spontaneously appearing mammary adenocarcinomas in murine bone marrow radiation chimeras and in mice preimmunized with monoclonal antibodies (MAb) detecting embryo-associated antigenic determinants. A correlation was seen between the ability of the embryo-immunized chimeras to produce cytotoxic antibody to the tumors, as assessed by an antibody-dependent cellular cytotoxic assay, and the permissiveness of the mice for growth of a tumor transplant. In addition, mice deliberately preimmunized with cytotoxic MAb (antibody-dependent cellular cytotoxic assay) allowed more rapid growth specifically of that tumor earlier found to be most sensitive to the MAb used for immunization. By comparing the changing antigenic phenotype of tumor cells serially passaged through different immunized, nonimmunized mice, evidence was found suggesting that immunization could cause either antigen modulation of transferred tumor cells or a (transient) selective advantage to antigenically discrete subpopulations within the heterogeneous tumor population. Finally, we have studied the growth pattern of tumor cells transplanted into mice immunized with rabbit antibodies directed against the murine MAb. In this case, tumor growth was slowed preferentially for the tumor reactive with the specific MAb, and again, predictable changes in the antigenic spectrum of tumor cells harvested from these animals were observed. Our overall findings are interpreted in terms of the involvement of networks of antibodies reacting with embryo-associated antigens in the regulation of growth of the murine mammary adenocarcinomas studied.

Adenocarcinoma↗
PubMed1983

Loss of promyelocytic maturation in HL60 sublines: a potential model for leukaemia progression.

The majority of cells of the human leukaemic line HL60 appear to be promyelocytes which can be stimulated to mature into functioning neutrophils. We report here the derivation of stable subclones from the parent line which differ. Two forms of variant were obtained: (1) those with a defined lesion, selected by resistance to kill by 6-thioguanine, which matured in the presence of DMSO and retinoic acid but not in hypoxanthine. They also continued to express peroxidase and a major granulocyte antigen, and (2) those obtained by clonal growth in DMSO which did not mature in the presence of any compound tested including hypoxanthine, DMSO, retinoic acid and actinomycin D and lacked granules, peroxidase and the granulocyte antigen. The concurrent loss of the characteristic of maturability and the phenotype of myeloid commitment suggests that the control of the two phenomena may be related. These variant cell lines provide a useful model in which to study how human leukaemic cells may become arrested in less differentiated stages of development.

Animals↗
PubMed1983

Growth and characterization of T cell colonies from human thymus.

A semisolid microculture system was used to study T cell colonies grown from human thymocytes. Colony growth was absolutely dependent upon media conditioned by peripheral blood leukocytes (PBL) in the presence of phytohemagglutinin. Plating efficiency was further enhanced by the addition of a non-T, adherent, radiation-resistant (7500 rad) PBL subpopulation, but was not enhanced by culture supernatants of these cells. The T colony precursor cell in the thymus occurred with a frequency of 8.0 X 10(-3) and had a surface receptor for the OKT3 monoclonal antibody. Thymocyte colony cells were functionally distinct from PBL and the major thymocyte population. The colony cells proliferated in response to T cell mitogens, but only in the presence of exogenous growth factors. The cells stimulated normal PBL in mixed leukocyte culture (MLC), but did not respond to alloantigens in MLC or in assays of spontaneous cytotoxicity. This culture system should prove helpful in the study of human thymocyte differentiation.

Adolescent↗
PubMed1982

A monoclonal antibody demonstrating specificity for drug-resistance cells.

We have described a monoclonal antibody with specificity for permeability-altered drug-resistant cells. This gamma G2b antibody was characterized by antibody-mediated complement-dependent cytotoxicity and by immunofluorescence analysis using a flow cytometer-cell sorter. Further experiments with the flow cytometer showed that vinblastine=resistant cells exposed to that drug had a wider range of fluorescence intensity and had a modal channel 4 times as bright as the same cells cultured in growth medium. We believe that this monoclonal antibody recognizes part of the "P' glycoprotein found on drug-resistant Chinese hamster ovary cells.

Animals↗