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Biomedical subjects

C R King

Publications and source records attributed to C R King.

At least 19 recordsLinked to original sources
PubMed1997

Multiple Grb2-protein complexes in human cancer cells.

Grb2 is an SH2/SH3 domain-containing adaptor protein that links receptor tyrosine kinases to the ras signaling pathway. The Grb2-SH2 domain binds phosphotyrosine sequences on activated tyrosine kinases, and one target of the SH3 domains is the ras-nucleotide-exchange factor Sos1. We have examined Grb2-protein interactions in human cancer cells that over-express the receptor tyrosine kinase erbB2. Our results show that the 2 Grb2-SH3 domains complex with Sos1, dynamin and at least 4 other proteins (p228, p140, p55, p28) in these cells. The 2 Grb2-SH3 domains bind these proteins differently, with the N-terminal SH3 domain interacting preferentially with p228, Sos1, p140 and dynamin. The C-terminal SH3 domain has higher affinity toward p28. The Grb2-SH3 domain interactions appear to be similar in erbB2 over-expressing breast, ovarian and lung cancer cells. Also, the major tyrosine-phosphorylated proteins that associate with Grb2 in erbB2 over-expressing cancer cells appear to be erbB2 and Shc. The multiple Grb2-SH3 domain interactions in these cells may mediate novel cellular functions.

3T3 Cells↗
PubMed1997

Potent antitumour activity of a new class of tumour-specific killer cells.

Two approaches to the antibody-directed targeting of toxic or cytolytic activity and augmentation of cellular immune responses have been explored for tumour immunotherapy, but so far success has been limited. Obstacles facing immunotherapy are the limited accessibility of antibodies or antibody conjugates to solid tumours and the difficulty in obtaining tumour-specific cytotoxic lymphocytes. Here we generate a new class of tumour-specific killer cells by genetically modifying lymphocytes to produce and secrete a targeted toxin against an oncoprotein overexpressed on breast and other tumour cells. The transduced lymphocytes were shown to have potent and selective cytotoxicity to tumours in culture and nude mouse models. The potent in vivo antitumour activity is probably a result of the migration of the lymphocytes to tumours as a targeted toxin carrier, and production and accumulation of the targeted toxins inside tumours as a producer. Our approach, which has features of both antibody-directed and cell-mediated immunotherapy, may have application in a gene therapy context.

ADP Ribose Transferases↗
PubMed1996

The performance of e23(Fv)PEs, recombinant toxins targeting the erbB-2 protein.

The overexpression of the erbB-2 (HER-2, neu) gene has attracted significant interest as a molecular target for the rational design of cancer therapies. This review examines the design and preclinical testing phase for one such experimental therapy, recombinant toxins targeted to the erbB-2 protein, termed e23(Fv)PEs.

ADP Ribose Transferases↗
PubMed1996

Preclinical testing of an anti-erbB-2 recombinant toxin.

The performance of OLX-209 indicates it should enter phase I clinical testing. OLX-209 is a recombinant toxin targeting the erbB-2 oncoprotein. The design of OLX-209 takes advantage of improvements in immunotoxin technology to produce a molecule that is smaller and more potent than a conventional chemically linked antibody-toxin conjugate. The targeting portion of OLX-209 is a single chain antibody structure derived from the anti-erbB-2 hybridoma, e23. This antibody has unusual specificity in that it does not bind to most normal tissue including peripheral nerve or kidney tissue. Preclinical testing shows in vitro activity against breast cancer cell lines in the pM range. Efficacy testing in five models of human cancer indicates that a dose of 43 micrograms/kg causes reproducible tumor regressions. Efficacy can be achieved on a variety of schedules of administration. The effective dose results in no measurable change in serum liver enzymes when delivered to mice or primates. The LD10 is over twice the effective dose in mice. The pharmacokinetics indicate a t 1/2 of 50 minutes for both mice and cynomolgus monkeys. Serum concentrations of more than ten times those observed at the effective dose can be achieved in monkeys with no evidence of toxicity. Antigenicity of OLX-209 is surprisingly low. These results form the basis for the clinical testing phase for OLX-209.

Animals↗
PubMed1995

Quantitative analysis of Grb2-Sos1 interaction: the N-terminal SH3 domain of Grb2 mediates affinity.

Grb2 is an adaptor protein that links receptor and cytoplasmic tyrosine kinases to the Ras signalling pathway by binding the Ras-specific guanine nucleotide exchange factor, Sos1, through its SH3 domains. The Grb2-SH3 domain binding has been localized to the carboxy-terminal two hundred amino acids of Sos1 (Sos1-c). By using real time biospecific interaction analysis (BIAcore), we studied the kinetic parameters and binding affinity of the Grb2-Sos1-c interaction. The binding of Grb2 to Sos1-c is a high affinity interaction with a moderate association rate (9.45 x 10(4) per M per s), a slow dissociation rate (13.8 x 10(-5) s), and an affinity constant of 1.48 nM. BIAcore measurements on isolated N-terminal and C-terminal SH3 domains (NSH3 and CSH3) further indicate that the high affinity Grb2-Sos1-c interaction is primarily mediated through the NSH3 domain (Kd = 1.68 nM). The CSH3 domain shows substantially reduced binding to Sos1-c in these measurements. Inhibition studies with BIAcore using proline rich peptides derived from the C-terminus of Sos1 show that there is a single major binding site for Grb2 in Sos1. This binding site is contained within the peptide N20, which corresponds to amino acids 1143-1162 of Sos1. This peptide completely blocks the Grb2-Sos1-c and NSH3-Sos1-c interactions with IC50 values of 8 microM and 4 microM respectively. The discrete interaction between the NSH3 domain and the N20 peptide may be amenable for drug discovery through screening or peptidomimetic approaches.

3T3 Cells↗
PubMed1995

Read Don Quixote.

Explore the source record for details and available documents.

Attitude to Health↗
PubMed1995

Nurses' perceptions of the meaning of quality of life for bone marrow transplant survivors.

Nurses play an integral role in the care of bone marrow transplant (BMT) patients from pre-transplant to posttransplant. The purpose of this study was to explore the nurses' perceptions of the impact of transplant on the quality of life (QOL) of survivors. The conceptual framework for the study was the model of QOL developed by Ferrell, Grant, Schmidt, Rhiner, Whitehead, and Forman (1992). It depicts the QOL domains of physical well-being, psychological well-being, social concerns, and spiritual well-being. One hundred fifty nurses responded to a mailed survey. The items were based on the Quality of Life-BMT Survey used previously with patients. Nurses' and patients' responses to the same item were compared. Results reflect that transplant nurses generally perceived patients as having a poorer QOL than they actually reported. Nurses described transplant as having both positive and negative consequences. Transplant was seen as providing patients with a second chance at life and an opportunity to increase their QOL. Nurses described negative consequences as resulting from physical losses, psychological distress, financial distress, and loss of relationships. The findings of the study have implications for training future transplant nurses and for improving nursing care for transplant patients.

Adult↗
PubMed1994

Improved binding and antitumor activity of a recombinant anti-erbB2 immunotoxin by disulfide stabilization of the Fv fragment.

e23(dsFv)-PE38KDEL is a recombinant immunotoxin composed of the Fv region of anti-erbB2 monoclonal antibody e23 connected to a truncated form of Pseudomonas exotoxin (PE38KDEL), in which the inherently unstable Fv heterodimer (composed of VH and VL) is stabilized by a disulfide bond engineered between structurally conserved framework positions of VH and VL. We have now found that e23(dsFv)-PE38KDEL is considerably more cytotoxic to antigen-positive cell lines than the corresponding single-chain immunotoxin. The basis for the enhanced cytotoxic activity is that the e23 dsFv-immunotoxin binds to erbB2 with greater affinity than the single-chain counterpart. The dsFv-immunotoxin had 4-fold increased binding compared to the scFv and almost identical to the binding affinity of e23 Fab. e23(dsFv)-PE38KDEL was also considerably more stable at 37 degrees C than the single-chain immunotoxin. The therapeutic potential of the disulfide-stabilized immunotoxin was compared with its single-chain counterpart using two animal models of immunodeficient mice bearing subcutaneous tumor xenografts of human gastric tumor N87 cells or human A431 epidermoid carcinoma cells. The antitumor effect of e23(dsFv)-PE38KDEL was significantly better than that of the single-chain immunotoxin. e23(dsFv)-PE38KDEL caused complete regression of tumors at doses which caused no toxic effects in mice, whereas the single-chain immunotoxin did not cause complete regressions at the same doses.

ADP Ribose Transferases↗
PubMed1994

Intracellular single-chain antibody directed against erbB2 down-regulates cell surface erbB2 and exhibits a selective anti-proliferative effect in erbB2 overexpressing cancer cell lines.

Overexpression of the tyrosine kinase receptor erbB2 is important in the pathogenesis of a variety of neoplasms. Based on this concept, targeted anti-cancer strategies have been designed to selectively eradicate erbB2 overexpressing tumor cells. These strategies have employed either monoclonal antibodies or antibody toxin molecules with specificity for the cell surface erbB2 protein. As an alternative strategy, anti-erbB2 single-chain immunoglobulin (sFv) genes were constructed to direct expression of intracellular anti-erbB2 antibodies. Expression of an endoplasmic reticulum (ER) form of the anti-erbB2 sFv resulted in a profound down-regulation of cell surface erbB2 in an erbB2 overexpressing ovarian carcinoma cell line. In addition, expression of the intracellular antibody resulted in marked inhibition of tumor cell proliferation. Whereas stable transfectants expressing the anti-erbB2 sFv could be dervied from non-erbB2 overexpressing cancer cell lines, expression of the intracellular antibody was incompatible with long-term survival of the erbB2 overpressing tumor cells. The ability to selectively 'knock-out' erbB2 demonstrates that cell surface localization of erbB2 is essential to its ability to induce aberrant cellular proliferation in tumor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

High-level expression of the ribosomal protein L19 in human breast tumors that overexpress erbB-2.

The erbB-2 (or HER-2 or neu) gene is amplified and overexpressed in approximately one-third of cancers of the breast, stomach, and ovary. Evidence is accumulating that erbB-2 overexpression is associated with decreased survival of breast cancer patients. In an effort to understand how erbB-2 overexpression might impart a more malignant potential to breast cancer cells, we have searched for evidence of changes in gene expression associated with erbB-2 overexpression. Using differential screening of a complementary DNA library we identified several complementary DNAs that represent mRNAs the expression of which may vary according to erbB-2 level. One complementary DNA was studied in detail. The mRNA encoding the ribosomal protein L19 (1.9 kilobases) was more abundant in breast cancer samples that express high levels of erbB-2 (P < 6 x 10(-7)). The level of L19 mRNA expression varied over a 1- to 64-fold range among the tumor samples. No evidence of gene amplification for L19 was identified. The L19 overexpression in these breast tumor samples was not associated with the increased expression of the mRNAs for other ribosomal proteins (S16 and L26).

Amino Acid Sequence↗
PubMed1993

Calling Jane: the life and death of a women's illegal abortion service.

In May, 1972, seven Chicago women were arrested and charged with performing illegal abortions. Over the course of the preceding five years, the members of Jane, as this illegal abortion collective was denoted, had arranged, assisted and performed nearly 15,000 illegal abortions. The very fact that Jane existed as long as it did and assisted as many women as it did, was evidence of the central role that abortion and other reproductive decisions play in women's daily lives. Jane began amid the political and social discontent of the late 1960s. Like the Chicago Women's Liberation Union, Jane was founded by women helping other women. This action was, in effect, a continuation of the centuries old women's health network. Records of the Chicago Women's Liberation Union, words and deeds of the city's feminists and interviews with members of Jane, permit a consideration of important medical, philosophical and historical issues that surround the turbulent issue of abortion. In this setting the boundaries between and definitions of lay and medical practitioners become indistinct, the differences between women-centered and physician-centered medical care become more obvious, and at the very least Jane provides evidence of a model system by which women a generation ago successfully confronted restrictive abortion practices.

Abortion, Illegal↗
PubMed1992

Recombinant anti-erbB2 immunotoxins containing Pseudomonas exotoxin.

Immunotoxins were made using five different murine monoclonal antibodies to the human erbB2 gene product and LysPE40, a 40-kDa recombinant form of Pseudomonas exotoxin (PE) lacking its cell-binding domain. All five conjugates were specifically cytotoxic to cancer cell lines overexpressing erbB2 protein. The most active conjugate was e23-LysPE40, generated by chemical crosslinking of anti-erbB2 monoclonal antibody e23 to LysPE40. In addition, a recombinant immunotoxin, e23(Fv)PE40, was constructed that consists of the light-chain variable domain of e23 connected through a peptide linker to its heavy-chain variable domain, which in turn is fused to PE40. The recombinant protein was made in Escherichia coli, purified to near homogeneity, and shown to selectively kill cells expressing the erbB2 protooncogene. To improve the cytotoxic activity of e23(Fv)PE40, PE40 was replaced with a variant, PE38KDEL, in which the carboxyl end of PE is changed from Arg-Glu-Asp-Leu-Lys to Lys-Asp-Glu-Leu and amino acids 365-380 of PE are deleted. The e23(Fv)PE38KDEL protein inhibits the growth of tumors formed by the human gastric cancer cell line N87 in immunodeficient mice.

ADP Ribose Transferases↗
PubMed1992

Therapy of an animal model of human gastric cancer using a combination of anti-erbB-2 monoclonal antibodies.

Amplification and/or overexpression of the erbB-2 gene have been demonstrated in 20-30% of adenocarcinomas of the breast, ovary, lung, and stomach and are associated with aggressive clinical course and poor prognosis. Interference with erbB-2 function by the use of monoclonal antibodies is a promising approach to the treatment of these diseases. In this study we demonstrate that a combination of two anti-erbB-2-specific antibodies inhibited the growth of human gastric tumor cells in vitro. This combination antibody therapy also inhibited the growth of human tumor cell lines growing as xenografts in nude mice and was able to dramatically reduce established tumors. This is the first reported observation of tumor regression induced by anti-erbB-2 monoclonal antibodies. Treatment was not curative in that tumors regrew after 6 weeks. Treatment with either single antibody alone did not inhibit cell growth or tumor formation. Pulse chase and tyrosine kinase activity experiments were used to investigate the activity of the erbB-2 gene product (gp185erbB-2). The formation of complexes by two antibodies was found to interfere with receptor function and mimic some properties of a typical receptor ligand. Selective interference of the erbB-2 receptor by combination antibody therapy may be advantageous for the treatment of human cancers.

3T3 Cells↗
PubMed1992

Determination of concentrations of adenosine and other purines in human term placenta by reversed-phase high-performance liquid chromatography with photodiode-array detection: evidence for pathways of purine metabolism in the placenta.

A robust analytical method, using reversed-phase high-performance liquid chromatography with gradient elution and photodiode-array detection, was used to measure six purines and beta-NAD+ in acid-soluble extracts of samples taken from six different regions of human term placenta. Resolution of the analyte peaks in chromatographic profiles of the extracts, and the use of optimized integration, allowed simultaneous quantitation of all seven analytes from a single chromatogram. Peak purity was confirmed via on-line analysis of peak spectra, utilizing the purity parameter treatment of spectral data. Major placental purines were adenosine, inosine, hypoxanthine and adenine. Except for adenine, concentrations of the purines varied by two-fold or more between different regions of each placenta, but concentration ratios, i.e., adenosine/inosine and inosine/hypoxanthine, were similar. The findings indicate that the pathway of ATP breakdown to hypoxanthine in ischemic human term placenta is via adenosine, and that regional differences in placental concentrations of adenosine and its metabolites may result from regional differences in degree of ischemia.

Adenosine↗
PubMed1992

Development of a shielded 241Am applicator for continuous low dose rate irradiation of rat rectum.

This paper describes the development of sources, applicators, and techniques that can be used to irradiate rat rectums with continuous irradiation at dose rates of interest in brachytherapy, either with the full circumference of the rectum irradiated, or with half of the circumference shielded from the radiation. The system uses encapsulated 241Am sources, to irradiate rat rectum with 60 keV photons continuously at a dose rate of up to 50 cGy/hr. Details of the design and fabrication of the 241Am sources, the rectal applicator, the dosimetry of the system, and the protocols for preparing and irradiating the rats, and for detecting early rectal injury using histological examination of irradiated rectum are presented. Highly effective shielding (attenuation factors as low as 0.04) of half of the circumference of the rat rectum was achievable. Unidirectional 241Am irradiators for intracavitary brachytherapy offer a unique tool for examining the effects of shielding a portion of the circumference of the rat rectum, on the radiation tolerance of the rectum.

Americium↗
PubMed1992

The ideological and technological shaping of motherhood.

Women's medical care, especially the care of birthing women, is increasingly based on technological innovations. While the use of electronic fetal monitoring, in vitro fertilization and cesarean section have benefited some women, the expanding use of medical technology distances women and their physicians. The problem is compounded because the application of medical technology is often clouded by a gender based ideology that defines women as mere reproductive beings. Forgotten is the recognition that the "facts" and interpretations generated by medical advance are subject to the same ideological bias as traditional beliefs and understandings about women. Forgotten is the women, the person, in the body. By seeing, hearing, touching and talking with women, physicians, not technological feats, provide a foundation for women's health based on the mutual interaction, understanding and respect between women and their physicians.

Female↗