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C M Steel

Publications and source records attributed to C M Steel.

At least 19 recordsLinked to original sources
PubMed1992

p53 mutations in breast cancer.

We have identified and analyzed 41 mutations in p53 in sporadic breast tumors from 136 unselected breast cancer patients and estimate that approximately 40% of such tumors contain p53 mutations. The frequency of G-T transversions and the incidence of guanosine mutations in the nontranscribed strand of the p53 gene were found to be higher than expected, and we suggest, therefore, that exogenous carcinogens have an etiological role in sporadic breast cancers. Mutations were recorded in 44 codons of the p53 gene, with no obvious mutational hot-spots, although mutations at codons 175, 194, 273, and 280 accounted for 25% of the changes. One germ-line mutation was found in 136 patients and so we conclude that constitutional mutation of p53 may be an uncommon etiological factor in breast cancer.

Base Composition↗
PubMed1992

Insertion of SMRV-H viral DNA at the c-myc gene locus of a BL cell line and presence in established cell lines.

Mutation of the c-myc gene locus has occurred during in vitro culture of the Burkitt lymphoma cell line Namalwa. Gene cloning and sequencing of this c-myc gene locus has revealed the insertion of incomplete copies of the Squirrel Monkey Retrovirus-Human (SMRV-H) proviral genome. Insertions of the SMRV-H genome were seen in all Namalwa cell lines tested, with multiple insertions being seen in some sublines. Viral particles with the morphology of type-D retrovirus, budding from these cells, were seen by transmission EM. New insertions of the genome were produced spontaneously in these cells. The origins of the type-D retrovirus and its implications for workers in the field are discussed.

Base Sequence↗
PubMed1992

p53 allele losses, mutations and expression in breast cancer and their relationship to clinico-pathological parameters.

The p53 locus on the short arm of chromosome 17 at 17p 13.1 was examined for loss of heterozygosity, mutation, mRNA and protein expression in 60 primary breast cancers. Allele loss around the p53 locus was detected in 19/45 informative tumours (42%). p53 mutations in the evolutionarily conserved exons 5 to 9 were detected in 17/60 (28%) by amplification mismatch and confirmed by direct DNA sequencing. p53 mRNA expression was detected by Northern blot in 36/59 (61%) of tumours, and p53 protein expression using antibody 1801 on frozen-tissue sections in 13/44 of the tumours examined. p53 mutation was significantly associated with oestrogen-receptor-poor tumours (p less than 0.01) and hence with poor prognosis, but not with other clinical or pathological parameters. There was no statistical correlation between loss of heterozygosity around the p53 locus at 17p13.1 and p53 mutation. Furthermore, p53 mutation was not associated with p53 expression detected by immunohistochemical staining with antibody 1801 or as p53 mRNA. In addition, events on 17p (allele losses, p53 mutation, p53 expression) were independent of c-erbB-2 expression. In breast cancer, by contrast with colorectal, lung and ovarian cancer, there appears to be no clear association between p53 DNA abnormalities and p53 expression.

Alleles↗
PubMed1992

Overexpression of the p53 protein and allele loss at 17p13 in ovarian carcinoma.

Mouse monoclonal antibodies PAb 240 and PAb 1801 which specifically immunoprecipitate p53 protein, were used to examine 27 fresh ovarian tumours (16 serous adenocarcinomas, six endometrioid carcinomas, one mucinous adenocarcinoma, one mucinous borderline tumour and three benign adenomas). Eleven out of 16 (69%) serous adenocarcinomas and one endometrioid tumour showed positive staining with one or both antibodies and none of the mucinous or benign tumours stained with either antibody. DNA from tumour and peripheral blood leukocytes was used to identify allelic deletions on chromosome 17p in tumours. 11/12 positively staining tumours showed less of heterozygosity (LOH) on 17p at the nearest informative locus to the p53 gene. In this series of ovarian tumours, LOH on 17p correlates closely with the aberrant expression of the p53 protein in a high proportion of advanced stage serous adenocarcinomas. This observation suggests that the p53 tumour suppressor gene is involved in the evolution of epithelial ovarian cancer (EOC) and may have prognostic significance.

Adenocarcinoma↗
PubMed1992

Enhancement of human T cell responses to allogeneic stimuli by factor VIII concentrates.

The effect of factor VIII concentrate, from commercial and National Health Services manufacturers, on in vitro lymphocyte proliferative response to allogeneic stimulator cells was investigated. Factor VIII preparations 'purified' by ion exchange or by monoclonal antibody affinity had no effect in this assay but lymphocyte proliferation in response to allogeneic cells was markedly and consistently enhanced by some intermediate purity factor VIII concentrates and, to a lesser extent, by a factor IX preparation. These preparations did not stimulate lymphocyte proliferation in the absence of other mitogens. The co-mitogenic factor(s) present in intermediate purity factor VIII was not identified. However, enhanced proliferation was not due to factor VIII itself, nor to albumin or fibronectin. The clinical relevance of the immunomodulatory activity of intermediate purity factor VIII concentrates in vitro is discussed.

Cell Division↗
PubMed1992

Immunological studies in HIV seronegative haemophiliacs: relationships to blood product therapy.

Immunological studies were performed on a group of 44 haemophilia A and 15 haemophilia B patients who were treated exclusively with blood products manufactured by the Scottish National Blood Transfusion Service (SNBTS). All patients were HIV seronegative throughout the study. Of the haemophilia A patients 14 (32%) had CD4+ lymphocyte subset counts less than or equal to 0.5 x 10(9)/l, compared with one (6%) haemophilia B patient and four (8%) controls. The percentage of activated T cells was greater than 5% in 19/33 (57%) with haemophilia A, 5/9 (55%) haemophilia B and 14/50 (28%) of control subjects. beta 2 microglobulin values greater than or equal to 2.0 mg/l were observed in 19 (43%) haemophilia A and four (26%) haemophilia B patients, compared with one (2%) control. No significant increases in serum interleukin-2 receptor concentrations were observed in 15 haemophilia A and one haemophilia B patients. Significantly elevated levels of IgG, IgM and IgA were observed in the haemophilia A group, but elevation of immunoglobulins was restricted to the IgG class in the haemophilia B group. Of the haemophilia A patients 16/30 (53%) and 6/11 (54%) haemophilia B patients had depression of cell-mediated immunity (CMI) as assessed by delayed-type hypersensitivity responses to intradermally injected recall antigens. There was no correlation between factor VIII or factor IX usage and changes in lymphocyte subsets, beta 2 microglobulin, and immunoglobulin levels. There was, however, a strong correlation between annual factor VIII usage and the degree of depression of CMI for those with haemophilia A but not for those with haemophilia B. No correlation between alterations in the immune parameters and disturbance of liver function tests was observed in either haemophilia A or haemophilia B patients. We conclude that alloantigen or non-HIV viral exposure due to repeated administration of factor concentrates brings about alterations in the immune response, and that these changes are more marked following exposure to intermediate purity factor VIII compared with factor IX concentrate.

Factor IX↗
PubMed1992

A significant proportion of patients with osteosarcoma may belong to Li-Fraumeni cancer families.

We studied the pedigrees of 17 index patients with osteosarcoma, recording malignant disease and cause of death for first- and second-degree relatives. There were seven cancers and five cancer deaths per 2151.5 person-years in first-degree relatives of osteosarcoma patients under the age of 50 years, a significantly greater incidence than in an age- and sex-matched population group (p < 0.001). This excess of malignancy was largely due to two families which fulfilled the criteria for the Li-Fraumeni cancer family syndrome. Both of these families were shown to have the genetic alterations in the p53 gene which have been implicated in this syndrome. Our study suggests that orthopaedic surgeons seeing new cases of osteosarcoma should arrange screening for familial malignancy.

Adolescent↗
PubMed1992

Familial breast cancer.

Familial clustering of breast cancer has been recognised for over a century but until recently a genetic basis has been suspected rather than proven. Epidemiological studies have tended to support the view that an autosomal dominant gene, with high but incomplete penetrance, accounts for most breast cancer families. However, it is likely that several different predisposing genes are present within most populations. Difficulties arise in a conventional 'linkage mapping' approach to identifying these genes, first, because it is not clear that genetically homogeneous groups of families can be recognised on the basis, for example, of mean age of onset or pattern of other cancers within the kindred and, second, because breast cancer is so common (affecting almost one in twelve women) that large affected kindreds are likely to include an admixture of sporadic (non-genetic) cases. Cytogenetic and 'Loss of Heterozygosity' (LOH) studies in sporadic breast cancers have pointed to several candidate loci for breast cancer genes but there is no clear consensus from these two approaches that might direct attention to any prime target region. Recent reports of tight linkage between familial breast cancer (early onset) and breast/ovarian cancer (regardless of mean age of onset) and a locus on chromosome 17q21 defined by the anonymous probe CMM86, have not been confirmed in detail but have led to the identification of a locus some 15 Mb centromeric of CMM86 that gives a high positive lod at very low recombination fraction in fifteen Edinburgh breast and breast/ovarian cancer families. The disease in the majority of such families therefore appears to be attributable to a mutant gene at 17q12-21. A much smaller proportion of familial breast cancer is accounted for by mutations in the p53 gene (17p13). Not all such families fulfil the criteria for Li-Fraumeni syndrome and not all of the inherited mutations lie within exon 7 of p53. Counselling of members of breast cancer families becomes more exacting as these genetic lesions are identified. It is essential to extend the collection of data and tissue (blood or fixed pathology material) as widely as possible to confirm linkage to a specific locus within each individual kindred, to define the precise mutation and to establish the cancer phenotype and its penetrance. In the course of these studies a substantial population of women at high risk of breast (and other) cancer will be identified. Resources should be directed to this population so that optimum procedures for screening and prevention can be developed.

Breast Neoplasms↗
PubMed1991

Determinants of HIV disease progression: six-year longitudinal study in the Edinburgh haemophilia/HIV cohort.

Markers of immune function present before infection may determine the subsequent course of disease in HIV-infected individuals. In 1983, we measured immune function in a group of haemophiliacs in Edinburgh. In 1984, 18 of these patients became infected with HIV-1 from contaminated factor VIII. We have followed-up these patients since their seroconversion. The rate of disease progression, as assessed by the appearance or not of AIDS symptoms or signs within five years of seroconversion, was related both to the concentration of total plasma IgM before exposure to infection and to the pattern of specific IgM and IgA anti-HIV response around the time of IgG seroconversion. Disease progression also correlated with concentrations of plasma interleukin-2 receptor (a marker of lymphocyte activation) and with the number and percentage of circulating DR + ve (activated) T cells. Our findings show that the extent of host immune reactivity, which may be genetically determined, is a powerful factor in the pathogenesis of HIV-associated disease.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Linked DNA markers for presymptomatic diagnosis of familial adenomatous polyposis.

41 symptom-free individuals aged 0-39 years who were at risk of familial adenomatous polyposis (FAP) were genotyped with six linked DNA probes. 28 individuals were informative for probes flanking the gene and 14 people assigned a probe-derived risk of over 0.93 were subsequently shown to be affected by clinical screening. 4 individuals who had been discharged from follow-up were designated high risk by this method. In those screened negative, risk was calculated from genotypic, colonic, and CHRPE findings and 89% of subjects had a risk below 0.003. An integrated risk analysis may have an important place in screening programmes for FAP.

Adenomatous Polyposis Coli↗
PubMed1991

Transforming growth factor beta 1 is implicated in the failure of tamoxifen therapy in human breast cancer.

Transforming growth factor-beta 1 (TGF-beta 1) is inhibitory for breast epithelial cells in vitro and treatment of breast cancer cell lines with tamoxifen results in a rise in TGF-beta 1 mRNA expression with associated inhibition of cell growth. To study whether these findings apply in vivo we examined TGF-beta 1 mRNA expression in an oestrogen-dependent mouse xenograft system following systemic treatment of the mice with tamoxifen. In agreement with in vitro studies. TGF-beta 1 mRNA expression was sustained at high levels and associated with a reduction in tumour size. A subsequent study of breast tumour tissue from 56 patients demonstrated high levels of TGF-beta 1 mRNA in 45 of the tumours. High expression was found to correlate with premenopausal status, but not with tumour oestrogen receptor content or other parameters. In a subgroup of 11 patients who had received tamoxifen therapy for 3 to 6 months prior to surgery, unexpectedly high levels of TGF-beta 1 mRNA were demonstrated in tumours increasing in size and unresponsive to tamoxifen. Data from this study indicate that in patients with breast cancer, TGF-beta 1 in the tumour may not behave as in vitro and xenograft studies have suggested. We speculate that failure of tamoxifen therapy may be due to failure of the autocrine inhibitory functions of TGF-beta 1 either alone or in combination with paracrine stimulation of stromal cells or angiogenesis and localised immunosuppression. Further studies of active TGF-beta 1, TGF-beta receptors and the interactions with other growth factors will be required to elucidate the precise role of TGF-beta 1 in human breast cancer and in the failure of tamoxifen therapy.

Adult↗
PubMed1991

Differential effects of CD45 CD45R and CD45R0 monoclonal antibodies in modulating human B cell activation.

We have examined the effect of monoclonal antibodies (MoAbs) to different epitopes of the leucocyte common antigen (LCA), CD45, on anti-human immunoglobulin-primed B cell activation. Binding of MoAbs to restricted epitopes present on CD45 glycoproteins of 180 kD and 220 kD (designated CD45R0 and CD45R, respectively) was found to promote B cell proliferation in the presence of T cells. CD45 MoAbs reactive with 'public' determinants on all four constituent members of the LCA family (180, 190, 205, and 220 kD) had either little effect or inhibited the basal B cell response to anti-immunoglobulin priming. Simultaneous immunofluorescent analysis of 5-bromodeoxyuridine incorporation and the expression of CD19 (B cell specific) or CD2 (T cell specific) identified the majority of responder cells as B lymphocytes. CD45R MoAbs significantly enhanced the B cell response to sub-optimal concentrations of interleukin-2. CD45 and CD45R0 MoAbs failed to elicit a similar response. Antibody to the interleukin-2 receptor (anti-Tac) partially blocked the CD45R-driven, T cell-dependent B cell proliferation.

Antibodies, Monoclonal↗
PubMed1991

MCC, a candidate familial polyposis gene in 5q.21, shows frequent allele loss in colorectal and lung cancer.

MCC is a gene located within human chromosome band 5q.21 that shows somatically acquired mutations in colorectal cancer, and may be identical to the gene responsible for inheritance of familial adenomatous polyposis. Here we demonstrate that alleles contiguous with or within MCC are deleted in a high proportion of sporadic colorectal carcinomas. Of 106 carcinomas that were informative concurrently at close-flanking sites both centromeric and telomeric to MCC, 41.5% showed acquired allele loss contiguous with MCC. Evidence is presented to show that the true frequency of loss of MCC alleles is higher still. In contrast, allele losses in chromosome 5 that were incompatible with involvement of MCC were very rare (2% of a total series of 201 informative tumours). Interstitial deletion was the commonest mechanism of allele loss, and L5.71-3, a probe known to include coding sequences of MCC, marks the most consistently deleted site. Moreover mapping of chromosome breakpoints with six probes within 5q.21 sited the common critical deletion in a 2.5 Mb region which included L5.71-3. However use of L5.71-3 itself suggested that critical deleted regions may lie on either side of the probed sequence. The simplest explanation for this unexpected finding is that MCC itself is the essential deleted gene, the lost exons lying sometimes centromeric to, sometimes telomeric to and occasionally within the region detected by L5.71-3. Tumours in which MCC-related alleles were lost by interstitial deletion were in general larger than those with other mechanisms of acquired homozygosity (e.g. mitotic recombination), but there were no other obvious associations with clinicopathological features. Between 20% and 25% of lung cancers also showed acquired allele losses contiguous with MCC. The significance of this observation is still to be determined, as lung tumours show allele losses at many other sites, but the specificity of the probes used in this study does establish that the 5q.21 losses in these tumours are compatible with involvement of MCC.

Adenomatous Polyposis Coli↗
PubMed1990

Five year prospective study of HIV infection in the Edinburgh haemophiliac cohort.

OBJECTIVE: To identify measures of immune state that reflect the course of HIV related disease in order to predict deterioration of symptoms and assess response to treatment. DESIGN: Five year longitudinal clinical and laboratory study. SETTING: Regional haemophilia centre, university virology laboratory, and Medical Research Council laboratory. PATIENTS: 32 Patients with haemophilia A exposed to a single batch of HIV contaminated factor VIII concentrate from the Scottish National Blood Transfusion Service in 1984 who were followed up regularly in Edinburgh (31) or abroad (one). MAIN OUTCOME MEASURES: Counts of circulating T cell subsets (CD4 and CD8); plasma beta 2 microglobulin, neopterin, and IgA concentrations; and delayed type hypersensitivity to multiple skin test antigens. RESULTS: 18 Patients who seroconverted after exposure had received significantly more contaminated factor VIII than the 14 who did not (mean 43 (range 9-109) v 15 (3-30) phials, p less than 0.01). The two groups were not distinguishable by other criteria before exposure. The group that seroconverted subsequently showed a progressive fall in mean circulating CD4 lymphocytes and an increase in plasma beta 2 microglobulin and neopterin concentrations. From 1987 patients in this group also showed an increase in mean circulating CD8 lymphocytes and in plasma IgA concentration, neither of which was seen in patients who did not seroconvert. Patients with HIV antibody who developed Centers for Disease Control category IV symptoms within five years after infection showed more extreme changes in all measures, except CD8 lymphocyte count, than those whose symptoms remained in categories II and III. Skin test reactivity declined to barely detectable levels in all patients positive for HIV antibody. CONCLUSIONS: Serial estimates of circulating CD4 lymphocytes and of plasma beta 2 microglobulin concentration are the most reliable measures of disease progression; of these, beta 2 microglobulin concentration seems to be the better predictor of impending serious symptoms. High IgA concentrations reflect rather than predict disease state. Individual variation in most measures is such that a wide range of measurements should be used in assessing the effects of trial treatment in HIV infected patients without symptoms.

Adolescent↗