PubMed Health⌕ Search

Biomedical subjects

G A Currie

Publications and source records attributed to G A Currie.

At least 19 recordsLinked to original sources
PubMed1985

Activation of N-ras in a human melanoma cell line.

DNA isolated from cell line Mel Swift, a human melanoma cell line, transforms NIH3T3 cells. Southern blot analysis of DNA from secondary foci revealed conserved 8.8- and 7.8-kilobase EcoRI fragments which hybridized with a human repetitive sequence clone, blur 8. The activated transforming gene was identified as N-ras, and the 8.8-kilobase EcoRI fragment from a secondary transformant was cloned. Synthetic 17-mer oligonucleotides which spanned either the normal codon 61 (CAA) or a mutant codon 61 (AAA) were used for hybridization. Cloned N-ras from melanoma cell line Mel Swift hybridized to the mutant (AAA) oligonucleotide. From this we predicted a glutamine-to-lysine substitution in amino acid 61, a change confirmed by conventional sequencing of the first and second exons of N-ras from cell line Mel Swift. Transfection experiments showed that only those recombinant clones with the mutation in position 61 were biologically active.

Amino Acid Sequence↗
PubMed1979

Monocytes and macrophages in malignant melanoma IV. Effects of C. parvum on monocyte function.

Assays for the capacity of peripheral-blood monocytes (a) to mature in vitro into macrophages, (b) to reduce nitro-blue tetrazolium (NBT) and (c) to lyse antibody-coated human Group A red cells, were applied to a group of 82 patients with histologically proven malignant melanoma. In patients with micrometastatic disease there was an enhancement of red-cell lysis and NBT reduction, suggesting that their monocytes are in some way "activated", whereas NBT reduction was suppressed in those with overt dissemination. Monocyte maturation in vitro was impaired in all patient groups to an extent which correlated with overall tumour burden. Corynebacterium parvum was administered i.v. to 12 patients with disseminated disease and by the intradermal route to 24 patients with micrometastatic disease. The 3 monocyte functions were significantly enhanced by C. parvum.

Bacterial Vaccines↗
PubMed1979

Microenvironmental arginine depletion by macrophages in vivo.

Since the tumour-selective cytotoxic activity of activated macrophages in vitro can be attributed to depletion of the culture medium of L-arginine by macrophage arginase, a series of experiments was designed to determine whether such a mechanism could operate in vivo. Extracellular fluid obtained from Gullino chambers within established tumours contained high levels of arginase, no detectable arginine and high levels of ornithine. When tumours were disaggregated into single-cell suspensions, arginase was readily detected within tumour macrophages but not within malignant cells. Inflammatory ascites induced in mice by Corynebacterium parvum was rich in arginase, depleted of L-arginine and cytotoxic in vitro to L5178Y and V79 cells. High levels of arginase in the ascites fluid were associated with resistance to challenge with syngeneic L5178Y cells. Lymph collected from the cisterna chyli in rats bearing a macrophage-rich sarcoma on the small bowel contained elevated levels of arginase, was depleted of arginine and contained increased concentrations of ornithine. We conclude that in sites of macrophage infiltration there is microenvironmental arginine depletion due to the action of arginase, and that arginase release could represent an important macrophage effector mechanism against a variety of targets, including malignant cells, virus-infected cells, fungi and parasites.

Animals↗
PubMed1979

Immunity as the predominant factor determining metastasis by murine lymphomas.

The metastatic behaviour of the L5178E (non-M) lymphoma and a highly metastatic subline L51787ES (M) were studied in syngeneic DBA2 mice. The non-M tumour rarely metastasizes in intact syngeneic mice, but produces extensive and rapidly lethal metastases when implanted into irradiated recipients. The metastatic behaviour of the M subline is unaffected by irradiation of the host. By conventional transplantation criteria, the non-M tumour is more immunogenic than the M subline. Both tumours, however, produce similar responses in a lymphnode weight-gain assay. Host-cell infiltration of the tumours growing s.c. is much greater in the non-M than the M, the infiltrating cells being Fc-receptor-positive and maturing into macrophages after 2 days in vitro. Although spontaneous in vitro motility of the M cells is much greater than that of the non-M, the metastatic behaviour of the tumours is clearly determined by host immunological responses.

Animals↗
PubMed1978

Monocytes and macrophages in malignant melanoma. III. Reduction of nitroblue tetrazolium by peripheral blood monocytes.

Peripheral-blood monocytes from normal individuals and from patients with malignant melanoma reduce nitroblue tetrazolium (NBT). A quantitative assay for dye reduction was applied to 25 healthy donors and 31 patients with malignant melanoma. NBT reduction expressed as dye reduction per monocyte was significantly impaired in patients with disseminated disease, and they responded poorly to a phagocytic stimulus. Monocytes from patients with micrometastatic disease, however, showed normal resting NBT reduction but, following exposure to a suspension of latex-polystyrene, showed significantly greater NBT reduction than those from normal individuals. Since NBT reduction is an indirect measure of intracellular hexose-monophosphate-shunt activity we conclude that the monocytes from patients with minimal disease are in some way activated.

Adolescent↗
PubMed1978

Repopulation of gamma-irradiated Lewis lung carcinoma by malignant cells and host macrophage progenitors.

Cellular repopulation in Lewis carcinoma irradiated with 60Co gamma-rays was examined by performing sequential cell-survival estimations using an in vitro soft-agar-colony assay. Following local irradiation (15--35 Gy) two distinct types of colony were seen: compact colonies with tightly packed cells and diffuse colonies with widely dispersed cells. Maximal diffuse colony formation in vitro was only obtained in the simultaneous presence of adequate numbers of compact colonies. After whole-body irradiation only compact colonies were observed. Only-cell survival data from compact colony counts correlated with cell survival estimated by the lung colony assay and we conclude that compact colonies are produced by clonogenic tumour cells. Cytochemical and immunological evidence showed that diffuse colonies were composed of macrophages. After local irradiation the initial kill of clonogenic tumour cells was dose dependent. At each dose level, repopulation began immediately and proceeded with a doubling time of about 1 day. Macrophage colony-forming cells (macrophage progenitors) per tumour were initially reduced by about 3 decades, but recovered very rapidly to reach pretreatment levels within 2 days. We conclude that at least two populations of clonogenic cells are present in Lewis lung carcinoma, tumour cells that repopulate irradiated tumours by in situ proliferation and host-macrophage progenitors that repopulate locally irradiated tumours by infiltration. The hazards of confusing host and tumour cell colonies in in vitro assay systems are stressed.

Cell Survival↗
PubMed1978

Differential arginine dependence and the selective cytotoxic effects of activated macrophages for malignant cells in vitro.

Normal and neoplastic cells from 4 species (man, rat, mouse and hamster) were examined for their dependence on exogenous L-arginine in tissue culture. The malignant cells required a higher concentration of L-arginine in the medium than their normal counterparts (with similar doubling times) to maintain optimal proliferation. Complete arginine deprivation resulted in equal growth inhibition of normal and malignant cells, but more rapid cytolysis of the malignant cell. Deprivation of L-arginine, followed 24 h later by rescue with L-arginine, allowed normal cells to proliferate, but the reproductive capacity of the malignant cells was irreversibly impaired. Since the cytotoxic activity of LPS-activated macrophages was associated with the release of arginase and was abrogated by excess L-arginine, it is suggested that the biological basis for the selective effects of such macrophages may reside in the L-arginine dependence of the target cells.

Animals↗
PubMed1978

Monocytes and macrophages in malignant melanoma. II. Lysis of antibody-coated human erythrocytes as an assay of monocyte function.

Peripheral blood mononuclear cells will lyse antibody-treated human erythrocytes. Using Group A red cells and a hyperimmune anti-A1 serum, we have devised a microassay for the cytolytic capacity of mononuclear cell suspensions. The effector cells responsible for red-cell lysis are mononuclear, adherent and phagocytic, and their activity is blocked by aggregated IgG. Their presence correlates well with non-specific esterase-containing cells and we conclude that they are monocytes. Dose-response curves of red-cell lysis plotted against numbers of monocytes were used to derive a simple parameter expressing the number of monocytes needed to lyse 15% of the 51Cr-labelled red cells. The assay was applied to a group of 27 normal controls and 36 patients with a histologically proven diagnosis of malignant melanoma. The results indicate that monocytes from patients show significantly greater lytic activity than those from the controls. These data suggest that monocytes from cancer patients are in some way activated, and that other defects in monocyte function which have been detected in cancer patients (defective chemotaxis and maturation) may be associated with monocyte "activation".

Antibody-Dependent Cell Cytotoxicity↗
PubMed1978

Specific active immunotherapy does not prolong survival in surgically treated patients with stage IIB malignant melanoma and may promote early recurrence.

A prospective trial with concurrent controls was designed to assess the effects of specific active immunotherapy in patients receiving intermittent cytotoxic chemotherapy (DTIC + Vincristine) as an adjuvant to surgery in Stage IIB malignant melanoma. The treated group received monthly irradiated allogeneic melanoma cells and BCG, and the controls BCG only. Sixteen patients in the treatment arm had a median relapse-free interval of 5 months, compared to 8 months in 12 controls given chemotherapy and BCG, and because of this we felt that continuation of the study was unjustified on ethical grounds. Although all the controls who relapsed did so at distant sites, 7/11 patients given specific active immunotherapy relapsed initially within the lymphatic drainage area of the primary tumour. The median intervals from starting treatment to relapse at distant sites, and the median survival were identical in the 2 groups. We conclude that immunotherapy comprising irradiated allogenic melanoma cells as employed in this study does not prolong survival in surgically treated Stage IIB malignant melanoma and may even promote early, local relapse.

Adult↗
PubMed1977

Monocytes and macrophages in malignant melanoma. I. Peripheral blood macrophage precursors.

A micro-assay designed to assess the capacity of peripheral blood mononuclear cells to differentiate in vitro into mature macrophages is described. In patients with "final common pathway" malignant melanoma, there was a highly significant deficiency in macrophage precursors (MPs). By conventional morphological criteria such patients did not show a significant monocytopenia. Serum factors do not seem to contribute to the MP defect in the patients. We conclude that these patients have an intrinsic functional defect in their peripheral blood monocytes, but the mechanisms responsible for this defect are as yet unknown.

Adhesiveness↗
PubMed1977

Inhibition of leukaemia blast cell motility as a test for specific antibody in acute adult myelogenous leukaemia.

Migration studies of acute myelogenous leukaemia blast cells in autologous diagnostic and remission sera from a series of 11 patients have demonstrated two factors. A factor of less than 70 000 molecular weight appears to potentiate blast cell migration whereas the other of molecular weights 100 000-250 000 inhibits blast cell migration relative to a standard non-immune AB serum. The low molecular weight fraction was found in the serum of patients prior to relapse while the greater molecular weight fraction was possibly an IgG antibody that increased in concentration with length of remission. The inhibitory factor was found in patients following immunotherapy and in one patient who received chemotherapy alone. An inhibitory factor was also consistently found in patients in overt clinical relapse following on remission induction and maintenance therapy.

Adult↗