Biomedical subjects

G K Ward

Publications and source records attributed to G K Ward.

11 recordsLinked to original sources

PubMed1992

Cellular heterogeneity in human transitional cell carcinoma: an analysis of optical properties and lectin binding.

Flow cytometry was used to measure the binding of a panel of ten fluorescein isothiocyanate(FITC)-conjugated lectins to fifteen samples of normal and neoplastic human urothelium. Concurrent measurement of light scattering and fluorescence permitted the quantification of lectin binding to cellular subpopulations defined by their light-scattering properties. In normal urothelium, we previously demonstrated levels of lectin binding to the cellular subpopulations derived from the superficial and intermediate cell layers which were higher than levels which bound to the subpopulation derived from the basal cell layer (Ward et al., 1987). This difference was most marked with Maclura pomifera agglutinin (MPA), Ricinus communis agglutinin (RCA) and Ulex europeus agglutinin (UEA). We now report a similar correlation between the degree of differentiation of a cellular subpopulation and the level of lectin binding in human transitional cell carcinomas (TCCs). Morphological differentiation in human TCCs is accompanied by alterations in cell-surface carbohydrates which are similar to those which accompany cellular differentiation in the corresponding normal tissue. No systematic difference in lectin binding was observed between the corresponding subpopulations of normal and neoplastic urothelial cells.

Carbohydrate Metabolism↗

PubMed1991

DNA cruciforms and the nuclear supporting structure.

Cruciforms have been suggested as potential recognition structures at or near origins of DNA replication in eukaryotic cells. Monoclonal antibodies with structural specificity for DNA cruciforms have been produced (Frappier et al. J. Mol. Biol. 193, 751, 1987). The effect of these antibodies, when introduced into permeabilized cells, was to increase overall DNA synthesis and relative copy number of genes (Zannis-Hadjopoulos et al. EMBO J. 7, 1837, 1988); this was interpreted to be a consequence of antibody stabilization of the cruciforms located at or near replication origins resulting in multiple initiations of DNA replication at a single site. Fluorescent labeling of nuclei with anti-cruciform antibodies produces a nonuniform pattern of fluorescence in cells arrested at the G1/S boundary which then changes with progression through S-phase (Ward et al. Exp. Cell Res. 188, 235, 1990). In order to determine the relationship of cruciform distribution in DNA with the nuclear matrix/chromosomal scaffold, we assessed the susceptibility of DNA containing cruciforms to digestion with DNase I. The majority of the cruciforms detectable at G1/S and throughout the nucleus are readily digested by DNase, suggesting that cruciform structures may not be intimately associated with matrix proteins. The fraction that is resistant to DNase I appears associated with nuclear membrane and the nucleolus. No cruciforms could be detected in metaphase chromosomes; cruciforms either are not present or are inaccessible--buried in the scaffold. The absence of cruciforms from metaphase chromosomes would be consistent with the viewpoint that the cruciform in vivo is a transient structure dependent upon and interacting with proteins essential for replication or transcription.

Animals↗

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

Clinical trials in cancer: the role of surrogate patients in defining what constitutes an ethically acceptable clinical experiment.

Doctors who treat lung cancer in Ontario were previously asked how they would wish to be managed if they developed non-small cell lung cancer and whether they would consent to participate in six clinical trials for which they might be eligible. The proportion of these expert surrogate patients who would consent to each clinical trial ranged from 11 to 64%. The results of this study were transmitted to the same group of doctors who were asked to comment on the ethical acceptability of each trial in the light of this information. The majority of physicians said that those trials to which less than 50% of expert surrogates consented should not have been opened to patients. Sixty-nine per cent of doctors thought that new trials should be evaluated in this way. We also present the results of a survey of 400 lay people in Ontario who were asked to imagine that they had lung cancer and whether they would consent to participate in two of these same clinical trials. Fifty per cent of lay people consented to a randomised trial of lobectomy versus segmentectomy in early, operable disease (LCSC-821) compared to 64% of expert surrogates, and 48% of lay people consented to a randomised trial of five different forms of chemotherapy in metastatic disease (SWOG-8241) compared to 19% of doctors. It was concluded that the lay people were unable to discern differences in the acceptability of clinical trials which were clear to experts in the field. Subsequently, respondents were told about the decisions which doctors would make in the same circumstances and asked if this information would modify their previous decisions. There is no net change in the proportion of patients consenting to the surgery trial but the proportion of people consenting to the chemotherapy trial decreased by 40%. The majority of lay people said that they would wish to have access to this type of information before consenting to participate in a clinical trial.

Attitude of Health Personnel↗

PubMed1987

Non-small cell lung cancer: how oncologists want to be treated.

One hundred and eighteen Canadian doctors who treat lung cancer were asked how they would wish to be managed if they had non-small cell lung cancer. Four clinical situations were described. The doctors' replies to the open-ended management questions were remarkably consistent in view of their diverse backgrounds. Although opinion was divided as to the role of immediate radiotherapy in inoperable cancer, and the role of post-operative radiotherapy following incomplete surgery, there was little controversy as to the role of chemotherapy. Three per cent of doctors wanted adjuvant chemotherapy after surgery for early disease, 9% wanted chemotherapy for advanced disease confined to the chest and 15% wanted chemotherapy for symptomatic metastatic disease. The implications of these results are discussed in the light of current recommendations for treatment of non-small cell lung cancer in the standard North American textbooks of oncology.

Canada↗

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

The use of expert surrogates to evaluate clinical trials in non-small cell lung cancer.

One hundred and eighteen doctors who treat pulmonary neoplasms in Ontario were asked how they would wish to be treated if they had non-small cell lung cancer. Four different scenarios were given. The physicians were then asked if they would consent to take part as subjects in one or more clinical trials for which they would be eligible in those situations. The proportion of respondents who would consent to each study ranged from 11% to 64%. Reasons given for refusing to participate as subjects in each trial were varied, but many felt that the trials offered unacceptable options for treatment. Medical oncologists consented to each study more frequently than radiation oncologists, respirologists or thoracic surgeons but all disciplines ranked the 6 studies in the same order of acceptability. It is concluded that some patients with non-oat cell lung cancer currently receive experimental therapies with high risk/benefits ratios which experts in the field would not accept for themselves. It is suggested that the expert surrogate system may be useful as an adjunct to the institutional review board in evaluating new trials before they are activated.

Attitude of Health Personnel↗

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

Cellular heterogeneity in normal and neoplastic human urothelium.

Cell suspensions derived from 2 specimens of normal human urothelium and 13 human transitional cell carcinomas were studied by discontinuous density gradient centrifugation. The histochemical and proliferative properties of the fractions were evaluated. In normal urothelium, DNA synthesis was restricted to a subpopulation of small round cells which could be partly separated from the more numerous pyramidal and giant cells on the basis of their higher physical density. Normal urothelium did not form colonies in agar. In well-differentiated tumors, the majority of cells present were low-density, elongated cells which histochemically resembled the differentiated pyramidal cells of normal tissue, but DNA synthesis and the ability to form colonies in agar were restricted to a subpopulation of high-density small round cells. Colony size analysis showed that intermediate-density bands contain cells capable of a few divisions which do not form large colonies. With increasing tumor grade, there was an apparent shift into the high-density clonogenic compartment.

Cell Differentiation↗

PubMed1976

Partial specific volume, expansibility, compressibility, and heat capacity of aqueous lysozyme solutions.

Density measurements have been made on aqueous lysozyme solutions at 20, 25, and 30 degrees. The apparent specific volumes, phi v, and expansibilities, phi e, have been determined from the density measurements and fitted to a function of concentration (weight per cent). Sound velocities and heat capacities have also been measured for various concentrations of lysozyme-water solutions at 25 degrees. From the density, expansibility, heat capacity, and sound velocity data at 25 degrees, the isothermal compressibility, phi k, for the lysozyme solutions have been calculated over a range of concentrations. All the physicochemical properties measured were found to be a linear function of the weight per cent of lysozyme. The number of water molecules hydrated to 1 mol of lysozyme was estimated from the volume and compressibility and found to be 162 at 25 degrees.

Mathematics↗

PubMedDate not supplied

Cellular heterogeneity in normal human urothelium: quantitative studies of lectin binding.

A panel of 10 FITC-labelled lectins (MPA, PNA, ConA, DBA, SBA, RCA-120, WGA, UEA, GS-I, GS-II+) was applied to cryosections of seven specimens of normal urothelium. Seven of the lectins (MPA, ConA, RCA, WGA, UEA, GS-I and GS-II) showed a pattern of increasing fluorescence intensity from basal to superficial cells of the urothelium whereas PNA, DBA and SBA showed more uniform binding throughout the urothelium. Urothelial cell suspensions labelled with FITC-lectins were studied by flow cytometry to quantify the variation in binding to different cells types. Three cellular subpopulations were identified in normal urothelium on the basis of their optical properties. Fluorescence intensity due to specific lectin binding was then measured separately for each subpopulation. Although there was some variation among individual cases, a general pattern emerged in this small series. WGA, RCA, and GS-II bind in large quantities to all urothelial cells while PNA, SBA, ConA and DBA show little binding. MPA, RCA, UEA and GS-I showed the most marked increase in fluorescence intensity from basal to superficial cells as observed microscopically and quantified by flow cytometry.

Adult↗