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Biomedical subjects

G D Birnie

Publications and source records attributed to G D Birnie.

At least 19 recordsLinked to original sources
PubMed1992

Tumour metastasis.

Explore the source record for details and available documents.

Disease Models, Animal↗
PubMed1992

The serum response element and an AP-1/ATF sequence immediately downstream co-operate in the regulation of c-fos transcription.

Transcription of the c-fos gene is activated in response to a wide variety of extracellular stimuli and several cis-acting transcriptional control elements have been characterized. One of these elements is called the serum response element (SRE) and here we investigate an interaction between this element and an AP-1/ATF-like sequence immediately downstream from the SRE. In growing cells these sequences activate transcription in an additive fashion whereas in quiescent cells they co-operate to repress transcription. This co-operation is disrupted upon separation of the elements which also alters the response of the elements to serum or 12-O-tetradecanoyl-phorbol-13-acetate (TPA) stimulation of quiescent cells. This separation also results in an increase of transcription in growing cells. A consensus AP-1 DNA-binding site can substitute for the AP-1/ATF-like sequence present in the c-fos promoter to activate transcription in an additive fashion with the SRE in growing cells, and co-operate in repression in quiescent cells. These observations show that any interaction that may be occurring between proteins binding to these elements results in a different pattern of transcriptional control in growing and quiescent cells. Alternatively, different proteins (or modified proteins) may complex with these sequences in the two different states of cell growth.

3T3 Cells↗
PubMed1992

Temporal relationships between induced changes in c-myc mRNA abundance, proliferation, and differentiation in HL60 cells.

Changes in the relative abundances of c-myc mRNA have been related to changes in other parameters of differentiation (histochemical, clonogenic) during the course of the differentiation of HL60 cells to monocytes/macrophages or to granulocytes. Induction of differentiation to monocytes/macrophages was marked by a rapid rate of appearance of committed cells (80 to 90% in 24 hours) and a concomitant rapid loss of c-myc mRNA. Induction of granulocytic differentiation resulted in a much slower rate of appearance of committed cells (50% in 48 hours), and a much faster rate of loss of c-myc mRNA (tenfold in 1 hour). These data are consistent with there being a direct link between down-regulation of the expression of c-myc and the onset of proliferation arrest and monocytic differentiation, but show there is no such association of c-myc mRNA abundance and proliferation or differentiation during the maturation of HL60 granulocytes.

Cell Differentiation↗
PubMed1991

Loss of amplification and appearance of a novel translocation site of the c-myc oncogene in HL-60 leukemia cells.

The chromosomal localization of c-myc sequences was determined by in situ hybridization in HL-60 cells (HL-60a) which contain an amplified c-myc locus and in an HL-60 subline (T-HL60) which has lost the amplification and has proportionately lower levels of c-myc RNA. While in HL-60a cells amplified c-myc sequences were found on the M3q+ marker chromosome, in T-HL60 cells one or few residual c-myc copies were found on a novel 4q+ marker chromosome. Comparative phenotypic analysis of HL-60a and T-HL60 cells show that the decrease in c-myc amplification/expression is not accompanied by changes in the malignant phenotype, namely in doubling time and clonogenic capability in semi-solid media. The significance of these results is discussed in the context of the role of c-myc amplification in the establishment and/or maintenance of the leukemic phenotype in HL-60 cells. In general, these results further underscore the utility of in situ hybridization analysis in identifying oncogene translocations which are not detectable by conventional karyotypic analysis.

Cell Line↗
PubMed1991

Restriction fragment length polymorphism analysis of the C1-inhibitor gene in hereditary C1-inhibitor deficiency.

Four out of 12 kindreds with Type I hereditary angio-oedema (HAE) were shown to have unique disease-related restriction fragment length polymorphism (RFLPs) in one allele of the C1-inhibitor gene. These RFLPs were used to localise the gene mutations responsible for them in each family. The four mutations affected exon 4, exon 6, exon 7 and exon 8, respectively. Mutations in exon 6 and exon 8 have not been described previously in Type I HAE. The other two mutations which comprised an exon 4 deletion and an exon 7 deletion have already been documented by other investigators. In each family the mutation was seen to cosegregate with the disease. Detection of a disease-related RFLP in 30% of the Type I HAE kindred tested is higher than other published studies, and reflects the larger number of restriction enzymes employed. These results suggest that Type I HAE is likely to be associated with a multiplicity of gene mutations as is seen in other genetic diseases. A new C1-inhibitor gene-related RFLP in the normal population was also characterised. This may be useful as an indirect marker of the mutant C1-inhibitor allele in certain families with Type I HAE.

Angioedema↗
PubMed1990

Interferon-mediated transcriptional and post-transcriptional modulation of complement gene expression in human monocytes.

The addition of lymphoblastoid interferon alpha, fibroblast interferon beta and recombinant interferon gamma to in vitro monocyte cultures produced dose-dependent increases in transcription rates of the genes encoding the second component of complement (C2), factor B (B) and C1 inhibitor, and the abundance of their respective mRNA. Interferon gamma was the most effective at stimulating transcription of the C1-inhibitor gene whereas interferons alpha and beta were more effective at increasing the transcription of the C2 and B genes. Transcription of the C3 gene was reduced by interferon gamma. None of these cytokines altered the level of transcription of the actin gene. Interferon-induced changes in the levels of transcription of the C2, B and C1-inhibitor genes occurred rapidly, with significant changes occurring within 30 min of exposure to these cytokines. Within 4 h of removal of the interferons from the culture fluid, the level of transcription of the C1-inhibitor, C2, B and C3 genes returned to control values, as did abundance of C2, B and C3 mRNA. However, the abundance of C1-inhibitor mRNA remained elevated in interferon-gamma-treated monocytes. Combinations of interferons produced less than additive effects on the stimulation of the transcription of C2, B and C1-inhibitor genes, whereas measurements of C1-inhibitor mRNA and B mRNA showed that interferon gamma acted synergistically with interferon gamma to increase the abundance of the mRNA. Their effects on C2 mRNA abundance were less than additive. The half-lives of C1-inhibitor, C2, B and C3 mRNA were not altered by interferon alpha, whereas interferon gamma shortened the half-life of C2 mRNA by approximately 50%, and prolonged the half-lives of B and C1-inhibitor mRNA approximately twofold and fivefold, respectively. The half-life of C3 mRNA was unaltered by either interferon. These results show that the large increase in C1-inhibitor synthesis which occurs in interferon-gamma-treated monocytes, is due to a combination of increased transcription and increased C1-inhibitor mRNA stability. They also suggest that the synergistic effects of interferon alpha together with interferon gamma on C1-inhibitor and factor B synthesis is also dependent upon increased transcription and increased mRNA stability.

Complement C1 Inactivator Proteins↗
PubMed1990

Modulation by interferons of the expression of monocyte complement genes.

Interferons-alpha, -beta and -gamma (IFNs-alpha, -beta and -gamma) stimulated the synthesis of the second complement component (C2), Factor B (B) and C1 inhibitor (C1-inh) by human monocytes in vitro. The degree of increase of the secretion rates of C2, B and C1-inh was dose-dependent and proportional to increases in the abundances of their respective mRNAs. IFN-gamma was the most effective at stimulating monocyte C1-inh synthesis, whereas IFN-alpha and IFN-beta were marginally more effective at stimulating monocyte C2 and B synthesis. Kinetic studies showed that the effect of the IFNs was rapid, with maximum stimulation occurring within 1-2 h for all three proteins. After the removal of IFNs from cultures the C1-inh mRNA abundance remained elevated for over 24 h in IFN-gamma-treated monocytes but returned to control levels within 8 h in IFN-alpha-treated and IFN-beta-treated monocytes. The abundances of C2 mRNA and B mRNA also returned to basal values within 8 h after removal of any of the three cytokines from the cultures. Both IFN-alpha and IFN-beta acted synergistically with IFN-gamma to stimulate synthesis of C1-inh and B. This synergistic effect only occurred when the cytokines were present in the cultures simultaneously. The effects of IFN-gamma plus IFN-alpha or IFN-beta on C2 synthesis appeared to be additive rather than synergistic. IFN-gamma inhibited synthesis of C3 by monocytes, but IFN-alpha and IFN-beta had no effect on the synthesis of this protein. Furthermore, none of the three cytokines had any effect on the expression of actin mRNA in monocytes.

Cells, Cultured↗
PubMed1990

Renin gene expression in nephroblastoma.

Most cases of nephroblastoma have high plasma levels of prorenin which is biologically inactive. Plasma prorenin levels fall to normal following nephrectomy. In order to ascertain whether renin synthesis occurs in nephroblastomas we decided to search for renin-specific mRNA using a cDNA probe and Northern blot analyses on total RNA purified from snap-frozen human tumour tissue obtained at nephrectomy. We demonstrated renin-specific mRNA in 5/11 (45 per cent) nephroblastomas. It was 1.6 Kb in length, similar to the mRNA detected in normal kidney tissue and in kidneys with renal artery stenosis. In one of the cases of nephroblastoma, in which we could detect no normal renin mRNA at 1.6 Kb, the cDNA probe hybridized with a higher molecular weight mRNA 3 Kb in length. We conclude that some nephroblastomas synthesize renin.

Gene Expression↗
PubMed1990

Regulation of the relative abundances of c-myc mRNAs in human promyelocytic HL60 cells.

Transcription of the c-myc gene is initiated mainly from two promoters, P1 and P2. By S1 nuclease analysis we found that there is 8 times more P2- than P1-initiated RNA in total RNA from HL60 cells. The half-lives of P1- and P2-initiated transcripts are 26 and 18 min, respectively, so the difference in the relative abundance of the mRNAs is not due to differences in their stabilities. The relative rates of transcription from the P1 and P2 promoters, estimated by in vitro nuclear run-on analysis, were found to differ by about 10-fold, sufficient to account for the difference in the steady-state levels of the two mRNAs. The abundance of c-myc mRNA changes dramatically during differentiation of HL60 cells. Dimethyl sulphoxide causes a very rapid reduction in total c-myc mRNA, while with phorbol ester a transient increase occurs followed by a more gradual decline. At no time during these dramatic alterations were significant changes detected in the relative abundance of P1- and P2-initiated mRNAs, or in their stabilities.

Cell Transformation, Neoplastic↗
PubMed1989

Monocyte C1-inhibitor synthesis in patients with C1-inhibitor deficiency.

Monocytes of seven out of eight patients with type 1 C1-inhibitor (C1-inh) deficiency (HAE) produced 40% as much C1-inh as monocytes from normal donors (controls). In contrast, monocytes from three patients with type 2 and three patients with acquired C1-inh deficiency produced similar amounts of C1-inh as controls. Recombinant gamma-interferon (gamma-interferon 10 ng/ml) stimulated C1-inh production of C1-inh (eight-10-fold) by control and patients' monocytes. Monocytes from patients with type 1 HAE contained 40% the level of C1-inh messenger ribonucleic acid (mRNA) found in control monocytes. Gamma-interferon increased the abundance of C1-inh mRNA by the same extent in both control and patients' monocytes. C1-inh protein and mRNA were undetectable in the monocytes of one patient, unless stimulated by gamma-interferon. Under these conditions, his monocytes produced comparable amounts of C1-inh (protein and mRNA) as gamma-interferon-stimulated monocytes of the other type 1 HAE patients. The data suggest that in most type 2 HAE patients there is a lesion in the C1-inh gene such that mRNA is transcribed by a single allele.

Angioedema↗
PubMed1989

Further evidence that the site of the breakpoint in the major breakpoint cluster region (M-bcr) may be a prognostic indicator.

A break in chromosome 22 within the major breakpoint cluster region (M-bcr) is a characteristic of Philadelphia chromosome-positive CML. We have determined the zone of the breakpoint in 80 chronic myelogenous leukemia (CML) patients and have confirmed our previous observation that a relationship does exist between the subregion of the breakpoint within the M-bcr and the average length of the chronic phase of the disease. Patients with a 3' breakpoint have a statistically shorter chronic phase (25 months) than patients with a 5' break (55 months). Thus, a molecular analysis of the M-bcr may provide a prognostically useful indicator of the probable length of the chronic phase, although the underlying mechanism of blast transformation, and the role (if any) of the hybrid phl-abl mRNA, is still unclear.

Blast Crisis↗
PubMed1989

Complement biosynthesis in human synovial tissue.

Molecular biological and immunochemical techniques have been used to study the synthesis of complement components by synovial tissue from patients with rheumatoid arthritis or osteoarthritis and by normal synovial tissue from a patient undergoing patellectomy. Using Northern and dot-blot analyses, mRNAs coding for C1-inhibitor, C2, C3, C4 and factor B have been detected, but not for C5. Quantitative analyses of the data have not shown any significant differences in the steady state levels of any of the mRNAs in synovium from rheumatoid arthritis and osteoarthritis patients. When synovial membrane fragments from rheumatoid arthritis, osteoarthritis patients or normal synovium were cultured in vitro, synthesis of C1-inhibitor, C2, C3, C4 and factor B detected by ELISA and C2, C3 and factor B were shown to be functionally active. This study thus provides conclusive evidence that synthesis of complement components occurs locally within normal and inflamed synovial tissue. The local synthesis of complement within normal synovial joints may be of importance in their defence against infection, whereas in inflamed joints it may contribute to the inflammatory response.

Arthritis, Rheumatoid↗