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Biomedical subjects

A Richmond

Publications and source records attributed to A Richmond.

At least 73 records · Page 4Linked to original sources
PubMed1988

Immunoaffinity purification of melanoma growth stimulatory activity.

Melanoma growth stimulatory activity (MGSA) is an endogenous growth factor produced by human malignant melanoma cells. When purified from conditioned medium from the Hs0294 human melanoma cell line, MGSA has been shown to be most reproducibly associated with a 16 kDa acid and heat stable moiety which is sensitive to trypsin and dithiothreitol. Monoclonal antibodies to MGSA have been produced. This report describes the use of FB2AH7 monoclonal antibody to prepare an immunoaffinity resin which binds the MGSA produced by Hs0294 cells. This resin was used to purify the MGSA antigen from Hs0294 human melanoma extracts and medium conditioned by the Hs0294 melanoma cell line. The immunoaffinity eluant obtained from both sources produced a significant stimulation in [3H]thymidine incorporation into DNA in Hs0294 cells and yielded similar profiles when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Upon elution of the material from the polycrylamide gels, a 16 kDa moiety was found to be more reproducibly active in the MGSA [3H]thymidine bioassay and enzyme-linked immunoadsorbent assay. The bioactivity of the 16 kDa material represents a 235,000-fold purification of MGSA.

Antibodies, Monoclonal↗
PubMed1988

Molecular characterization and chromosomal mapping of melanoma growth stimulatory activity, a growth factor structurally related to beta-thromboglobulin.

Melanoma growth stimulatory activity (MGSA) is a mitogenic polypeptide secreted by Hs294T human melanoma cells. Comparison of the N-terminal sequences of the 13 and 16 kd MGSA species with the cDNA sequence revealed that the mature form of human MGSA is maximally 73 amino acids long. Expression of the cDNA in mammalian cells results in the secretion of this peptide with mitogenic activity. MGSA is structurally related to the platelet-derived beta-thromboglobulin and to several other polypeptides. These factors may constitute a family of growth factors. MGSA mRNA was detected in a variety of cell types. The level of MGSA mRNA in melanoma cells is strongly elevated by treatment with MGSA. MGSA is the gene product of a recently detected gene gro. The gene was mapped to chromosome 4 (region q13----q21). This same region also contains genes for two of the structurally related factors, for c-kit, a receptor for an as yet unidentified ligand, and for 'piebald trait', an inherited skin pigmentation disorder.

Amino Acid Sequence↗
PubMed1988

Melanoma growth stimulatory activity: isolation from human melanoma tumors and characterization of tissue distribution.

Melanoma growth stimulatory activity (MGSA) is an acid and heat stable, auto-stimulatory growth factor which was first isolated from culture medium conditioned by the Hs294T human melanoma cell line. In this report, we describe the purification of MGSA from acid ethanol extracts of Hs294T tumors grown in nude mice using a series of Bio-Gel P30, reverse phase-high performance liquid chromatography and heparin-sepharose steps. This modified procedure provides a 10-fold improved yield of MGSA over previously published procedures. Purified MGSA-stimulated melanoma cell growth in both 3H-thymidine and cell number assays over a concentration range of 0.06 to 6 ng/ml. The MGSA bioactivity was primarily associated with fractions which exhibited molecular weights of 16 and 13-14 Kd based upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Purified platelet-derived growth factor (PDGF), insulin-like growth factor (IGF-1), transforming growth factor-beta (TGF beta), and epidermal growth factor (EGF) in combination with TGF beta did not stimulate 3H-thymidine incorporation in Hs294T cells under the conditions used for MGSA bioassay. Monoclonal antibody to MGSA was used to screen melanoma and benign nevus cultures as well as fixed sectioned tissue for MGSA. The majority of the melanoma cultures were MGSA positive, while most nevus cultures were MGSA negative. However, when fixed sectioned tissue was screened for MGSA immunoreactivity, melanoma tissue was MGSA positive and three-fourths of the benign nevi were MGSA positive. In addition, epidermal keratinocytes and several tissues exhibiting proliferative disorders contained immunoreactive MGSA. These data suggest that MGSA may be a normal regulator of growth and that the microenvironment of the cell may regulate both production of MGSA and response to MGSA.

Animals↗
PubMed1988

High yield purification of melanoma growth stimulatory activity.

Tumor cells produce a variety of hormones and growth factors that are associated with modulation of the growth pattern of malignant cells. Hs294T human malignant melanoma cells produce a monolayer mitogen, melanoma growth stimulatory activity (MGSA), that stimulates the growth of Hs294T cultures in serum-free medium. MGSA has been purified to homogeneity from conditioned medium of Hs294T human malignant melanoma cells using acetic acid extraction of the crude conditioned medium followed by three chromatographic processes, including gel-filtration, heparin-Sepharose, and reverse-phase HPLC. MGSA was eluted from the heparin-Sepharose resin with 0.1-0.3 M NaCl. The binding affinity is similar to that of platelet-derived growth factor (PDGF) and epidermal growth factor (EGF) but much less than many endothelial cell-derived growth factors which require significantly higher salt concentrations for elution. These procedures resulted in a final yield of purified MGSA that was significantly greater than yields obtained using previously reported procedures. The homogeneous 16,000 and 13,000 molecular weight moieties obtained by means of these procedures exhibited similar bioactivities (stimulating a 2- to 3-fold increase in Hs294T cell growth) over a 0.06-6 ng concentration range. This bioactivity was progressively inactivated during storage at -80 degrees C. These results indicate that the combination of heparin-Sepharose chromatography and reverse phase-HPLC provides a more efficient means of purification of MGSA.

Cell Line↗
PubMed1988

Sympathetic (alpha-beta) or calcium channel blockade for hypertensive myocardial infarction? A haemodynamic comparison of labetalol and nifedipine.

The haemodynamic impact of alpha- and beta-adrenoceptor blockade (labetalol) was compared with that of slow-calcium channel blockade (nifedipine) in 32 patients with sustained elevation of systemic arterial pressure (systolic blood pressure greater than 160; diastolic blood pressure greater than 95 mmHg) following a recent myocardial infarction (6-22 h). Patients with normal (pulmonary artery occluded pressure; (PAOP less than 18 mmHg; n = 16) or impaired (PAOP greater than 18 mmHg; n = 16) left ventricular function were randomized to labetalol (1 mg/kg i.v. 15 min) or nifedipine (20 mg sublingually) and haemodynamic profile was measured over 2 h. Both drugs equally reduced mean systemic arterial pressure (P less than 0.01 versus pretreatment control), and presumably left ventricular afterload; however, the heart rate (P less than 0.01) and cardiac index (P less than 0.01) increased after nifedipine, contrasting with reductions in both variables following labetalol (P less than 0.01). The elevated left ventricular filling pressure was reduced by both labetalol (P less than 0.05) and nifedipine (P less than 0.01) but the reduction was greater following nifedipine (-2 mmHg versus -5 mmHg, P less than 0.05). Thus both compounds were equally effective hypotensive agents. Labetalol consistently reduced cardiac stroke work and double product, important determinants of myocardial oxygen requirements; however, nifedipine afforded some improvement in cardiac performance in patients with left ventricular dysfunction.

Adrenergic alpha-Antagonists↗
PubMed1988

Ocular findings in partial trisomy 3q. A case report and review of the literature.

The authors report the ocular findings in a patient with partial trisomy 3 [46, XY-15, der(15), t(3;15) (q26;128) mat] and review the literature on this chromosomal anomaly. The patient's main ocular finding was infantile glaucoma. The patient's mother was phenotypically normal and carried a balanced chromosome translocation. Awareness of the ocular abnormalities associated with partial trisomy syndromes is essential since more children with these syndromes survive today than in the past.

Chromosomes, Human, Pair 3↗
PubMed1987

Preparation of a monoclonal antibody to a melanoma growth-stimulatory activity released into serum-free culture medium by Hs0294 malignant melanoma cells.

Autostimulatory growth factors may contribute to the ability of malignant cells to escape normal growth controls. We have previously shown that Hs0294 human malignant melanoma cells release into culture medium an acid-soluble, heat-stable, trypsin-sensitive, autostimulatory monolayer mitogen which can be purified from acetic acid extracts of conditioned medium by gel filtration, reverse-phase high-performance liquid chromatography, and preparative electrophoresis. The majority of this melanoma growth-stimulatory activity (MGSA) resides in a 16-Kd moiety, though bioactivity is also associated with 24-26 and less than 14-Kd forms of MGSA (Richmond and Thomas: J Cell Physiol 129:375, 1986). In order to further characterize this growth factor, monoclonal antibodies were prepared against a partially purified preparation of the autostimulatory melanoma mitogen. Monoclonal antibody clones were selected based on supernate inhibition of 3H-thymidine incorporation in serum-free Hs0294 melanoma cultures. One of these, termed FB2AH7, slows, but does not completely block, the growth of Hs0294 cells in serum-free medium in a dose-dependent manner. This antibody does not slow the growth of normal rat kidney fibroblasts, which neither produce nor require this mitogen, in either serum-free medium or medium containing 0.8% calf serum. This monoclonal antibody also blocks the mitogenic effects of partially purified preparations of this melanoma growth stimulatory activity (MGSA) on both Hs0294 cells and normal rat kidney fibroblasts. The FB2AH7 antibody has been demonstrated to bind MGSA by Western blot and by immunoprecipitation procedures. Western blot analysis of reverse-phase high-performance liquid chromatography purified growth factor demonstrated that FB2AH7 antibody binds to the 16-Kd and approximately 13-14-Kd forms of MGSA. FB2AH7 antibody can be used in immunoprecipitation experiments to bind the approximately 13-16-Kd forms of MGSA. The specificity of the binding of FB2AH7 antibody for MGSA but not other growth factors has been demonstrated in a modified dot blot assay. These data thus support the hypothesis that MGSA is an autostimulatory melanoma mitogen distinct from other growth factors.

Animals↗
PubMed1987

First-line treatment of left ventricular failure complicating acute myocardial infarction: a randomised evaluation of immediate effects of diuretic, venodilator, arteriodilator, and positive inotropic drugs on left ventricular function.

A prospective randomised trial compared the immediate haemodynamic effects of intravenous diuretic (frusemide), venodilator (isosorbide dinitrate), arteriolar dilator (hydralazine), and positive inotropic stimulation (prenalterol) as first-line therapy for acute left ventricular (LV) failure following myocardial infarction. Forty-eight patients with transmural myocardial infarction and a pulmonary artery occluded pressure (PAOP) of greater than 20 mm Hg were studied within 18 h of admission to a coronary care unit. Both frusemide (-4 mm Hg; p less than 0.01) and isosorbide dinitrate (-6 mm Hg; p less than 0.01) reduced LV filling pressure without change in cardiac index and heart rate. Although both hydralazine and prenalterol increased cardiac index (p less than 0.01), the reduction in LV filling pressure (-2 mm Hg; p less than 0.05) was less than with frusemide and isosorbide dinitrate, and was associated with an increased heart rate (+8 and +13 beats min-1; p less than 0.01). These data suggest that in acute heart failure following myocardial infarction the four treatment modalities could be ranked in descending order of potential benefit as follows: venodilatation (isosorbide dinitrate)--decrease of LV pressure/work; diuretic therapy (frusemide)--decrease of LV pressure/work offset by a transient pressor effect; arteriolar dilatation (hydralazine)--decrease of LV pressure/work and of PAOP, but offset by tachycardia; and positive inotropic therapy (beta 1-agonist prenalterol)--tachycardia and augmented LV afterload. Combination of the former and latter agents, because of their differing modes of action, should offer haemodynamic advantages over monotherapy and deserves further evaluation.

Adult↗
PubMed1986

Purification of melanoma growth stimulatory activity.

The Hs0294 human malignant melanoma cell line produces a monolayer mitogen that stimulates the serum free growth of low-density cultures of Hs0294 cells. This report describes the purification of that mitogen, termed MGSA for melanoma growth stimulatory activity, from serum-free conditioned medium from the Hs0294 cultures. MGSA has been purified from acetic acid extracts of lyophilized conditioned medium by gel filtration, reverse-phase high-pressure liquid chromatography (RP-HPLC), and preparative electrophoresis, resulting in a greater than 400,000-fold purification. MGSA bioactivity resides in acid- and heat-stable polypeptides of high and low molecular weight (24-28 kd and less than 14-16 kd). However, the majority of the activity is reproducibly associated with the approximately 16-kd moiety eluting from RP-HPLC at approximately 35% acetonitrile. Reduction with dithiothreitol or B-mercaptoethanol results in a loss of biological activity but does not convert the 24-28-kd moieties to the less than 14-16-kd forms of MGSA. 125I-MGSA that has been purified by preparative electrophoresis (16 kd) specifically binds to Hs0294 melanoma cells and retains 100% of the growth-stimulatory activity. The 16-kd MGSA stimulates the proliferation of Hs0294 cells at concentrations of 0.3-30 pM. The electrophoretic mobility of MGSA is also unaltered by the preparative electrophoresis procedure, further demonstrating that this procedure does not alter the biochemical integrity of the growth factor. Purified MGSA does not enable anchorage-independent growth of normal rat kidney (NRK) cells and is therefore different from the previously described transforming growth factors. The amino acid composition of MGSA differs from that of other previously described growth factors. These data demonstrate that MGSA represents a separate class of growth factors with biological and biochemical properties different from other growth factors.

Amino Acids↗
PubMed1986

Growth factor and cytogenetic abnormalities in cultured nevi and malignant melanomas.

It has been proposed that benign nevi that fail to differentiate normally may undergo stepwise growth and morphologic changes resulting in progression toward dysplastic nevi, which in some cases progress into malignant melanoma. In this study, we sought to determine the relationship between production of endogenous growth factors and the appearance of chromosomal abnormalities in cultured nevi and melanomas. Newly established cultures from 8 nevi with benign histology and 6 malignant melanomas, and 2 malignant melanoma cell lines were studied. Assays for mitogenic growth factors were based on stimulation of [3H]thymidine incorporation into DNA in Hs0294 malignant melanoma cells, produced by serum-free conditioned medium from nevus or melanoma cultures. Karyotypes were examined in cultures of an equivalent passage. Three of the 8 nevus cultures were mitogen-negative and displayed normal karyotypes; one nevus culture was mitogen-positive and had a normal karyotype, although the biopsied tissue demonstrated histologic evidence of benign melanocytic proliferation; one was mitogen-negative initially, but had an extra chromosome 8 in 2 of 50 cells; 3 were mitogen-positive and chromosomally abnormal. Each of the cultures in this latter group exhibited reciprocal translocation (rcpt) as the only identifiable abnormality [rcpt(6;15), rcpt(10;15), rcpt(15;20)], or a constitutional rcpt(4;5). Thus, there was direct correlation between growth factor production and chromosome abnormality in 6 of 8 benign nevus cultures. In the newly established melanoma cultures there was also concordance between growth factor and chromosomal status; conditioned media from 4 of 6 were mitogen-positive by at least one assay, and all 4 of the mitogen-positive cultures had chromosomally abnormal cell populations. Of the 2 melanoma cultures negative for growth factors, one was also negative for chromosome abnormality; the other had chromosomal change consisting of increased polyploidy. Both melanoma cell lines had abnormal karyotypes and were mitogen-positive. Though numerous chromosome changes were noted in the karyotypically abnormal melanoma cells, 6 of the 8 cultures exhibited abnormalities in chromosomes 1, 6, and/or 7. These data suggest that steps in the progression from benign nevi toward dysplastic nevi or malignant melanoma include: proliferation resulting from altered production of endogenous mitogenic growth factors; and development of specific chromosomal abnormalities.

Cells, Cultured↗
PubMed1985

Intravenous amrinone in left ventricular failure complicated by acute myocardial infarction.

Hemodynamic dose-response effects of intravenous amrinone were studied in 22 male patients aged 38 to 62 years with left ventricular failure occurring within 18 hours of acute myocardial infarction. After hemodynamic confirmation of a raised left-sided cardiac filling pressure--pulmonary artery occluded pressure greater than 20 mm Hg--patients were randomized to either low-dose infusion of amrinone (200 micrograms/kg/hr for 30 minutes, 400 micrograms/kg/hr for 30 minutes and then 800 micrograms/kg/hr for 30 minutes) or high-dose infusion of the drug (800, 1,600 and 3,200 micrograms/kg/hr sequentially, each for 30 minutes). Hemodynamic measurements were obtained at 1 hour before amrinone and at the end of each infusion step. Low-dose infusion of amrinone resulted in a progressive increase in cardiac output (p less than 0.05) and stroke volume (p less than 0.05) and progressive reductions in pulmonary artery occluded pressure (p less than 0.01) and systemic vascular resistance (p less than 0.05). Systemic blood pressure and heart rate were unchanged. High-dose infusion resulted in a similar increase in cardiac output (p less than 0.05) but no change in stroke volume owing to associated tachycardia (p less than 0.01). There was a significantly greater decrease in pulmonary artery occluded pressure compared with the low-dose infusion (p less than 0.05), and systemic arterial diastolic and mean pressures were also decreased (p less than 0.05). The decrease in systemic vascular resistance was of a similar order to that induced by the low-dose infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Characterization of autostimulatory and transforming growth factors from human melanoma cells.

Serum-free growth of the human malignant melanoma cell line Hs0294 is associated with production of transforming growth factor-alpha and an autostimulatory melanoma mitogen (melanoma growth-stimulatory activity, MGSA). The transforming activity is characterized by stimulation of anchorage-independent growth of normal rat kidney fibroblasts and competition with 125I-epidermal growth factor for binding to normal rat kidney cells. The second activity, MGSA, stimulates the anchorage-dependent growth of human melanoma cells in serum-free culture medium. When acetic acid extracts of Hs0294 conditioned medium are subjected to Bio-Gel P-30 chromatography followed by reverse-phase high-pressure liquid chromatography, the majority of the transforming growth factor-alpha elutes at 30 +/- 4% acetonitrile, while the major peak of MGSA elutes at 35 +/- 3% acetonitrile. These data indicate that the anchorage-dependent serum-free growth of the Hs0294 human melanoma cell line is apparently dependent upon the autostimulatory melanoma mitogen, MGSA, which is separable from the 125I-epidermal growth factor competing activity produced by these cells.

Chromatography, Gel↗
PubMed1983

Evaluation of transsphenoidal hypophysectomy in the management of patients with advanced malignant melanoma.

Transsphenoidal hypophysectomy was performed in 13 patients with advanced malignant melanoma. Although three minor responses were observed, there were no complete or partial responses. All three patients with bone pain had a decrease in discomfort lasting 1-2 months. All five patients with minor responses or stable disease had postoperative decreases in the excretion of the dihydroxyphenylalanine (DOPA) metabolite 3-O-methyldopamine; all but one patient with clinical progression had postoperative increases in excretion. Average survival of those whose postoperative excretion fell (143 +/- days; range, 60-217+) was significantly longer (P less than 0.004) than that of those whose postsurgical values rose (30 days; range, 15-58).

Adult↗
PubMed1983

Extraction of a melanoma growth-stimulatory activity from culture medium conditioned by the Hs0294 human melanoma cell line.

Extracts of conditioned medium (CM) from Hs0294 human malignant melanoma cells stimulate [3H]thymidine incorporation and an increase in cell number in serum-depleted Hs0294 cells. This activity is acid and heat stable, nonproteolytic, protease sensitive, contains disulfide bonds and elutes broadly from a Bio-Gel P-30 column with an approximate molecular weight range of 6,000 to 25,000. Hs0294 CM also stimulates [3H]thymidine incorporation in nonmalignant human nevus cells and normal rat kidney fibroblast cells but not in human fibroblasts. There was only limited competition with 125I-epidermal growth factor in binding assays. Hs0294 CM extracts stimulate anchorage-independent growth in normal rat kidney fibroblast cells in soft agar but not in Hs0294 cells, nevus cells, or human fibroblasts. This second activity elutes from the Bio-Gel P-30 column in two positions with apparent molecular weights of 27,000 and 11,000.

Agar↗
PubMed1982

In vitro growth promotion in human malignant melanoma cells by fibroblast growth factor.

Bovine pituitary fibroblast growth factor (FGF) stimulates the incorporation of [3H]thymidine into DNA in serum-depleted cultures of some but not other human melanoma cells. The melanotic malignant melanoma cell line MIRW exhibited a 40% increase in [3H]thymidine incorporation into DNA and a 48% increase in cell number in response to 3.73 x 10(-9) M FGF. This same concentration of FGF produced a 22% increase in [3H]thymidine incorporation in the melanotic melanoma cell line Hs0294. However, FGF had no effect on the amelanotic melanoma cell line Hs0675, early-passage cultures of a human amelanotic melanoma (W-1), or early-passage cultures of a congenital nevus (N-1).

Cell Division↗