Biomedical subjects

S M Anderson

Publications and source records attributed to S M Anderson.

At least 91 records · Page 5Linked to original sources

PubMed1995

Activation of src-related tyrosine kinases by IL-3.

The activation of src-related tyrosine kinases following IL-3 stimulation was examined in 32Dcl3 cells. Three src-related tyrosine kinases were activated following IL-3 stimulation: fyn, hck, and lyn. 32Dcl3 cells were transfected with retroviral vectors expressing each of these kinases and independent clones overexpressing each kinase were isolated. In cells overexpressing either fyn or hck, IL-3 stimulated a rapid increase in catalytic activity, which remained elevated longer compared with the kinetics observed in parental 32Dcl3 cells. An increase in the number of tyrosine-phosphorylated proteins in the presence and absence of IL-3 stimulation was observed in cells overexpressing fyn or hck. Transfection of 32Dcl3 cells with a retroviral vector encoding lyn also resulted in an elevated level of kinase activity, although the increase was not as dramatic as that observed with fyn or hck. Consistent with observations in parental 32Dcl3 cells, a high basal level of lyn kinase activity was observed in unstimulated lyn-transfected cells and IL-3 stimulation resulted in an approximate threefold increase in kinase activity. Overexpression of c-src in 32Dcl3 did not result in IL-3-stimulated activation of c-src, indicating specificity for fyn, hck, and lyn. While the overexpression of fyn, hck, or lyn in 32Dcl3 cells resulted in increased kinase activity and IL-3 stimulated tyrosine phosphorylation, it did not render the cells more sensitive to IL-3. These results suggests that in addition to the JAK2 tyrosine kinase, src-related kinases may play a significant role in signal transduction by cytokine receptors.

Animals↗

PubMed1995

Human parvovirus B19 can infect cynomolgus monkey marrow cells in tissue culture.

The human pathogenic parvovirus B19 cannot be grown in standard tissue culture but propagates in human bone marrow, where it is cytotoxic to erythroid progenitor cells. We now show that parvovirus B19 can replicate in cynomolgus bone marrow. Cynomolgus monkeys may be a suitable animal model for pathogenesis studies of parvovirus B19.

Animals↗

PubMed1995

Comparative analysis of human papillomavirus detection by PCR and non-isotopic in situ hybridisation.

AIMS--To assess the relative diagnostic performance of the polymerase chain reaction (PCR) and non-isotopic in situ hybridisation (NISH) and to correlate these data with cytopathological assessment. METHODS--Paired analysis of human papillomavirus (HPV) detection was performed by PCR and NISH on exfoliated cervical cells from 122 women attending a routine gynaecological examination. PCR amplification followed by generic and HPV type specific hybridisation was compared with NISH on a parallel cervical smear. RESULTS--Overall, 32 cases were positive by NISH and 61 positive by PCR. Of the 105 cases in which both PCR and NISH were interpretable, 76 (26%) were normal smears, 20 of which were HPV positive by NISH and 37 (49%) by PCR. Of 17 borderline smears, two were NISH positive and 12 PCR positive. Eight of nine smears containing koilocytes were positive by NISH and seven by PCR. Of three dyskaryotic smears, none were NISH and two were PCR positive. The concordance of NISH and PCR in these samples was 57%. To assess sampling error, NISH and PCR were performed on an additional 50 cases using aliquots from the same sample. This increased the concordance between assays to 74%. Filter hybridisation of PCR products with the cocktail of probes used in NISH (under low and high stringency conditions) demonstrated that several cases of NISH positivity could be accounted for by cross-hybridisation to HPV types identified by PCR but not present in the NISH probe cocktail. CONCLUSIONS--Sampling error and potential cross-hybridisation of probe and target should be considered in interpretation of these techniques. PCR is more sensitive because it provides for the amplification of target DNA sequences. In addition, the PCR assay utilised in this study detects a wider range of HPV types than are contained in the cocktails used for NISH. However, PCR assays detect viral DNA present both within cells and in cervical fluid whereas NISH permits morphological localisation.

Cervix Uteri↗

PubMed1995

Glucose suppression of insulin secretion in chronically hyperglycemic fetal sheep.

Previous observations in fetal sheep indicate that glucose may inhibit as well as enhance insulin secretion. To study conditions involved in inhibition of insulin secretion, we compared changes in plasma insulin concentration in response to acute increases in glucose and arginine concentrations in a group of normal, late gestation fetal sheep (euglycemic controls, EC) and a comparable group made chronically hyperglycemic by constant maternal glucose infusion (hyperglycemics, HG). After 7-10 d of maternal and fetal hyperglycemia, fetal glucose concentrations (G) were significantly increased in the HG group (0.98 +/- 0.07 mM EC, 2.00 +/- 0.11 mM HG, p < 0.001) but fetal plasma insulin concentrations (I) were not significantly different (57 +/- 7 pM EC, 71 +/- 9 pM HG, p = 0.2). Furthermore, the I/G ratio was significantly decreased in the HG group (60 +/- 9 EC, 40 +/- 4 HG, p = 0.03) and during a hyperglycemic glucose clamp (delta G approximately equal to 1.4 mM), glucose-stimulated increase in steady state I was less in the HG than in the EC fetuses (mean delta I/delta G = 106 +/- 15 EC, 61 +/- 10 HG, p = 0.01). An arginine infusion at the end of the clamp produced similar increases in I in the EC and HG groups (delta I = 824 +/- 116 pM EC, 906 +/- 131 pM HG, p = 0.45). There were no differences between groups for blood oxygen saturation and content, pH, or lactate concentration. After 14-17 d of hyperglycemia, glucose-stimulated increase in I was even more reduced in the HG fetuses than observed at 7-10 d. Decreased insulin response to arginine also was present, although pancreatic insulin concentration was not decreased. Glucose-stimulated increase in I returned to normal after 7 d of no glucose infusion and euglycemia. These data indicate that glucose-stimulated insulin secretion is reversibly decreased by marked, chronic hyperglycemia. Because pharmacologic inhibitors of insulin secretion (e.g. streptozotocin or alloxan) were not used, and oxygenation, pH, and lactate values were similar between the two groups, this decrease of insulin secretion appears to be glucose-specific, although mechanisms involved can include both glucose and amino acid (arginine) stimulation processes. Such decrease in fetal insulin secretion may limit the rate of fetal glucose utilization during chronic hyperglycemia and thereby modulate the rate of fetal growth.

Animals↗

PubMed1994

Resistance to parvovirus B19 infection due to lack of virus receptor (erythrocyte P antigen).

BACKGROUND: The presence of a specific cellular receptor is thought to be necessary for susceptibility to viral infection. The erythrocyte P antigen is the cellular receptor for parvovirus B19. We hypothesized that the rare persons with the p phenotype, whose erythrocytes do not have this receptor, would be naturally resistant to B19 infection, which causes erythema infectiosum. METHODS: Blood samples were collected from two populations in cross-sectional studies. We determined the P antigen phenotype of the red cells and tested plasma for anti-B19-specific antibodies. Bone marrow from donors of known P antigen phenotype was inoculated with parvovirus B19. Infectivity was measured by assays of erythroid progenitor cells, dot blot analysis, and in situ hybridization for B19 DNA, and an immunofluorescence assay for viral-capsid proteins. RESULTS: Of the 17 subjects with the p red-cell phenotype, who did not have P antigen on their erythrocytes, none (0 of 11 and 0 of 6) had serologic evidence of previous parvovirus B19 infection. In contrast, the seropositivity rates in the two control groups were 71 percent (53 of 75, P < 0.001) and 47 percent (32 of 68, P = 0.03). In vitro, bone marrow from donors with the p phenotype maintained normal erythropoiesis despite very high concentrations of virus, with no evidence of infection of erythroid progenitor cells by parvovirus B19. CONCLUSIONS: People who do not have P antigen, which is the cellular receptor for parvovirus B19, are naturally resistant to infection with this pathogen.

Adolescent↗

PubMed1994

Fluid restitution and blood volume redistribution in anesthetized rabbits in response to vasoactive drugs.

BACKGROUND: Vasoactive drugs could alter the fluid restitution from the tissue and redistribute blood volume between the macrocirculation and microcirculation. METHODS AND RESULTS: With bolus injections of vasoactive drugs in anesthetized rabbits, we measured the changes in blood and plasma density for the determination of the volume of restitution and redistribution. Epinephrine 3.5 micrograms/kg caused a fluid loss to the tissue, leading to a transient decrease in total blood volume by 2.30 mL/kg. Because of blood volume redistribution, the peak volume reduction was accompanied by a volume reduction of 0.81 mL/kg from the macrocirculation and 1.49 mL/kg from the microcirculation. Phenylephrine 70 micrograms/kg caused a peak reduction in total blood volume of 1.40 mL/kg (with 0.41 mL/kg from macrocirculation and 0.99 mL/kg from microcirculation). Nitroprusside 7 micrograms/kg increased the blood volume by 1.44 mL/kg (0.83 mL/kg macro and 0.61 mL/kg micro), nitroglycerin 7 micrograms/kg by 1.48 mL/kg (0.97 mL/kg macro and 0.51 mL/kg micro), and isoproterenol 7 micrograms/kg by 2.07 mL/kg (0.68 mL/kg macro and 1.39 mL/kg micro). All plasma (or blood) density changes measured for the five drugs (with epinephrine, phenylephrine, and nitroprusside done over a wide dosage range) correlated linearly with the drug-induced changes in arterial pressures. CONCLUSIONS: These results indicate that vasoactive drugs alter total blood volume and the volume of microcirculation and macrocirculation.

Anesthesia↗

PubMed1994

Direct effects of intravenous anesthetics on pulmonary vascular resistance in the isolated rat lung.

We determined the direct effects of thiopental, ketamine, midazolam, etomidate, and propofol on pulmonary vascular resistance (PVR), the relationship of the direct effects to the baseline PVR, and the possible interaction with functional endothelium. The intravenous anesthetics were injected randomly into 1) endothelium-intact isolated rat lungs which were either unconstricted or constricted with angiotensin II (n = 10), and 2) lungs with endothelial injury produced by electrolysis (n = 10). In endothelium-intact lungs thiopental (0.5 and 5.0 mg/kg) and etomidate (3.0 mg/kg) significantly (P < 0.05) increased PVR by 3% +/- 1%, 30% +/- 7%, and 29% +/- 5%, respectively. Ketamine (3.0 and 100 mg/kg) and propofol (20 mg/kg) significantly (P < 0.05) decreased the PVR by 6% +/- 1%, 15% +/- 1%, and 8% +/- 1%, respectively. Midazolam (0.3 and 3.0 mg/kg) and smaller doses of etomidate (0.3 mg/kg) and propofol (2.0 mg/kg) did not affect PVR. These responses did not vary with the baseline PVR over a twofold range. The effects of thiopental, ketamine, etomidate, and midazolam were not altered by endothelial injury. In contrast to the vasodilation produced by propofol in normal lungs, propofol (20 mg/kg) significantly (P < 0.05) increased the PVR by 8% +/- 2% after endothelial injury. In conclusion, this study demonstrates that thiopental and etomidate are direct pulmonary vasoconstrictors, ketamine and propofol are direct pulmonary vasodilators, and midazolam has no direct effects in the isolated rat lung. Further, these effects on pulmonary vasculature do not vary with baseline PVR, and only propofol appears to have endothelium-dependent effects.

Anesthesia, Intravenous↗

PubMed1994

Human papillomavirus detection and p53 expression in clear-cell adenocarcinoma of the vagina and cervix.

OBJECTIVE: To determine whether infection with oncogenic human papillomavirus (HPV) and/or altered expression of the tumor suppressor protein p53 is associated with clear-cell adenocarcinoma of the vagina or cervix. METHODS: Paraffin-embedded tissue specimens were studied from 14 women with clear-cell adenocarcinoma of the vagina or cervix. Nine women had a history of intrauterine diethylstilbestrol exposure. Human papillomavirus DNA was amplified via the polymerase chain reaction using consensus L1 primers and was detected by dot blot hybridization with a generic HPV probe and type-specific oligonucleotide probes. P53 protein was detected by immunohistochemical analysis with a mouse monoclonal antibody, DO-7. RESULTS: Three tumors contained HPV 31 DNA sequences. Eight tumors were HPV DNA-negative and three were indeterminate for HPV. P53 was detected in ten tumors; it was undetectable in the three tumors containing HPV 31 and in one tumor indeterminate for HPV. Three patients presented with or later developed metastatic disease. In each case, the tumor, including sites of metastasis, was HPV-negative and p53-positive. CONCLUSIONS: These findings suggest that infections with oncogenic HPVs may be a cofactor in the development of clear-cell adenocarcinoma of the vagina or cervix, though this association is less than that reported for squamous or non-clear-cell adenocarcinomas. Prior studies have shown that detection of the p53 protein by immunohistochemistry correlates with mutations in the p53 tumor suppressor gene. The detection of p53 in HPV-negative clear-cell adenocarcinoma suggests a second mechanism in the etiology of these rare tumors.

Adenocarcinoma, Clear Cell↗

PubMed1993

Erythrocyte P antigen: cellular receptor for B19 parvovirus.

The pathogenic human parvovirus B19 replicates only in erythroid progenitor cells. This virus was shown to bind to blood-group P antigen, as measured by hemagglutination. Erythrocytes lacking P antigen were not agglutinated with B19. Purified P antigen (globoside) blocked the binding of the virus to erythroid cells and the infectivity of the virus in a hematopoietic colony assay. Target cells were protected from infection by preincubation with monoclonal antibody to globoside. Knowledge of a parvovirus receptor has implications for understanding the pathogenesis of parvovirus infections and for the use of parvoviruses in gene therapy.

Antibodies, Monoclonal↗

PubMed1993

The discrimination of high-risk HPV types by in situ hybridization and the polymerase chain reaction.

The parameter Tmt has been defined by non-isotopic in situ hybridization and describes the tissue melting temperature (Tmt) of human papillomavirus (HPV) DNA sequences. In this study, multiple in situ hybridization signals for HPV types 16, 31 and 33 in individual archival biopsies hybridized with genomic probes are shown by polymerase chain reactions to be due to cross-hybridization of probe sequences to a single tissue target. Tmt is independent of viral type but depends on the homology between probe and target when using nick-translated whole genomic probes. The difference between Tm and Tmt is not due to the presence of viral capsid protein. Multiple HPV signals in archival material should not therefore be interpreted as indicative of multiple HPV infection unless adequate stringency conditions have been employed or they are present in morphologically distinct areas of the biopsy. Furthermore, extrapolation of calculated DNA homologies to non-isotopic in situ hybridization analysis may not be appropriate. A hybridization signal does not imply probe and target identity: this has implications for HPV typing in clinical material.

Capsid↗

PubMed1993

The human neuroblastoma cell line, IMR-32 possesses a GABAA receptor lacking the benzodiazepine modulatory site.

GABAA receptors were identified in IMR-32 cell membranes by the binding of [35S]t-butyl-bicyclophosphorothionate ([35S]TBPS) to the chloride channel. GABA (IC50 2.2 microM), muscimol (IC50 0.8 microM), picrotoxin (IC50 1.7 microM), pentobarbitone (IC50 108 microM), etomidate (IC50 53 microM), chlormethiazole (IC50 98 microM) and Ro 5-3663 (IC50 280 microM) all inhibited [35S]TBPS binding. The potency of these drugs at the [35S]TBPS binding site in IMR-32 cell membranes did not correlate with their potency on [35S]TBPS binding to rat cortical membranes (linear correlation of pIC50 values, r = 0.75, NS). No specific binding of the benzodiazepine ligands [3H]flunitrazepam or [3H]Ro 15-4513 to IMR-32 cell membranes was observed. Chloride efflux from IMR-32 cells was studied using the fluorescent dye 6-methoxy-N-(3-sulphopropyl) quinolinium. Chloride efflux was stimulated by GABA and muscimol (0.1-100 microM) but not by the GABAB agonist baclofen (100 microM). In the absence of exogenous GABA chloride efflux was stimulated by chlormethiazole (1-100 microM) in a picrotoxin-sensitive manner. Flurazepam (1-100 microM) both alone and in the presence of GABA had no effect on chloride efflux. It is concluded that IMR-32 cells contain a functional GABAA receptor which differs from that in rat cortex both in its general pharmacology and specifically in the absence of the allosteric modulatory site sensitive to benzodiazepines.

Animals↗

PubMed1993

Distribution of human papillomavirus types in genital lesions from two temporally distinct populations determined by in situ hybridization.

We examined 341 paraffin-embedded cervical tissues for human papillomavirus (HPV) DNA by in situ hybridization. The genital lesions examined represented tissue biopsies from two temporally distinct populations (1964 to 1965 and 1988 to 1989). Biotinylated probes to 14 different HPV types were used in our analysis: HPV types 6, 11, 16, 18, 31, 33, 35, 42, 43, 44, 45, 51, 52, and 56. The number of HPV DNA-positive specimens and the distributions of HPV types were similar for these two populations. Human papillomavirus DNA sequences were detected in approximately 50% of the tissues from each time period. Of the low-grade lesions (condyloma/cervical intraepithelial neoplasia 1 [CIN 1]) 52% (1964 to 1965) and 35% (1988 to 1989) were positive for HPV DNA by in situ hybridization. Among the high-grade lesions (CIN 2/CIN 3), 41% (1964 to 1965) and 67% (1988 to 1989) had detectable HPV sequences. Approximately 15% of the tissues with minimal histopathologic changes also contained HPV DNA. Human papillomavirus types 16 and/or 18 were the most common viral types in lesions from both time periods, followed by types 31/33/35; 6/11, 51/52; and 42/43/44, 45/46. Types 16 and/or 18 were strongly associated with high-grade lesions. Five percent of the HPV-positive lesions demonstrated evidence of multiple infections. Our results indicate that HPV DNA sequences can be detected readily by in situ hybridization in archival materials, even those prepared more than 25 years ago. In addition, analysis of HPV type distributions demonstrates that recently isolated HPV types (42, 43, 44, 45, 51, 52, and 56) were equally represented in tissues from both time periods.

Biopsy↗

PubMed1993

Effects of chronic stress on anterior pituitary and brain corticotropin-releasing factor receptors.

[125I]Corticotropin-releasing factor binding was measured in membrane homogenates prepared from the anterior pituitary, frontal cortex, motor cortex, somatosensory cortex, mesolimbic area (olfactory tubercle and nucleus accumbens), caudate putamen, hypothalamus, midbrain, and cerebellum from control and chronically stressed rats. The stressor consisted of 3 or 14 days of around-the-clock intermittent foot-shock (approximately one trial per 5-min frequency) that could be avoided or escaped on 90% of the trials presented by pulling a ceiling chain. Plasma corticosterone levels were almost doubled in stressed rats following 3 days of chronic stress and remained significantly elevated in rats stressed for 14 days as compared to controls. Plasma corticotropin levels were similar in controls and stressed animals in both the 3- and 14-day experiments. [125I]Corticotropin-releasing factor binding was decreased in anterior pituitary and frontal cortex following 3 days of chronic stress; binding affinity of anterior pituitary membranes was not different between control and stressed animals. [125I]Corticotropin-releasing factor binding was similar in control and 3-day-stressed animals in the other brain areas examined. After 14 days of chronic stress, hypothalamic [125I]corticotropin-releasing factor binding was decreased in stressed rats as compared to control animals but no other differences were seen. The decrease in the apparent number of anterior pituitary corticotropin-releasing factor receptors following 3 days of stress may be due, in part, to increased plasma corticosterone levels and/or increased corticotropin-releasing factor secretion during that time.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗

PubMed1993

A trial of recombinant human superoxide dismutase in patients with Fanconi anaemia.

Fanconi anaemia (FA) is a rare genetic disorder that predisposes to the development of aplastic anaemia and neoplasia. The pathophysiologic hallmark of FA is increased susceptibility to chromosomal breakage. Superoxide metabolism has also been shown to be involved in the cellular pathophysiology of FA. Human SOD (rh-SOD), an enzyme which dismutates superoxide, has recently been cloned and expressed in yeast. We treated four FA patients with a 2-week infusion of rh-SOD (25 mg/kg d daily) to determine whether rh-SOD had any effect on haemopoietic progenitor cell growth or on the abnormal cellular phenotype. We found that lymphocyte chromosomal aberrations induced by diepoxybutane were decreased during rh-SOD treatment in two patients and that bone marrow progenitors were increased in one patient.

Adolescent↗

PubMed1993

Identification of the GABAA receptor alpha 3 subunit in the IMR-32 neuroblastoma cell line.

A previous report has described the presence of t-[35S]-butylbicyclophosphorothionate binding sites and GABA-gated Cl- flux in the human neuroblastoma IMR-32 cell line. We now report the further characterisation of this binding site and, even more important, the identification of the GABAA receptor alpha 3 sub-unit expressed in these cells. Cell membranes prepared from IMR-32 cells were screened by immunoblotting for reactivity with various GABAA receptor alpha subunit-specific antibodies. Of these, only anti-Cys alpha 3 454-467 antibodies recognised specifically and in a dose-dependent manner an immunoreactive band. This M(r) 58,000 immunoreactive species and the N-deglycosylated derivatives were both coincident with the respective homologues found in both calf cerebral cortex membranes and purified receptor preparations. This is the first report of the identification of a specific GABAA receptor subunit expressed in a human cell line, and it therefore provides a convenient model for the study of receptor structure and regulation.

Animals↗

PubMed1993

Inhaled nitric oxide: dose response and the effects of blood in the isolated rat lung.

Inhaled nitric oxide (NO) is a vasodilator selective to the pulmonary circulation. Using isolated rat lungs, we determined the dose-response relationship of NO and the role of blood in mediating pulmonary vasodilation and selectivity. Inhaled 20, 50, 100, and 1,000 ppm NO attenuated (P < 0.001) hypoxic pulmonary vasoconstriction by 16.1 +/- 4.9, 22.6 +/- 6.8, 28.4 +/- 3.5, and 69.3 +/- 4.2%, respectively. Inhaled 13, 34, 67, and 670 ppm NO attenuated the increase in pulmonary arterial pressure secondary to angiotensin II more (P < 0.001) in Greenberg-Bohr buffer- (GB) than in blood-perfused lungs (51.7 +/- 9.9, 71.9 +/- 8.9, 78.2 +/- 5.3, and 91.9 +/- 2.1% vs. 14.3 +/- 4.1, 23.8 +/- 4.6, 28.4 +/- 3.8, and 55.5 +/- 5.9%, respectively). Samples from GB- but not blood-perfused lungs contained NO (93.0 +/- 26.3 nM). Intravascular NO attenuated the response to angiotensin II more (P < 0.001) in GB- (with and without plasma) than in blood- (hematocrit = 41 and 5%) perfused lungs (75.6 +/- 6.4 and 70.9 +/- 4.8% vs. 22.2 +/- 2.4 and 39.4 +/- 7.6%). In conclusion, inhaled NO produces reversible dose-dependent pulmonary vasodilation over a large range of concentrations. Inhaled NO enters the circulation, but red blood cells prevent systemic vasodilation and also a significant amount of pulmonary vasodilation.

Administration, Inhalation↗

PubMed1993

Coronary angioplasty for acute myocardial infarction in a hospital without cardiac surgery.

We evaluated, retrospectively, the hospital records of 100 consecutive patients with acute myocardial infarction who underwent emergency coronary angiography and percutaneous transluminal coronary angioplasty between January 1984 and August 1990. Intracoronary streptokinase (250,000 to 1 million units) was administered to 46 of these patients. Reperfusion was achieved in 82 patients, 8 of whom died in the hospital within 30 days. Angioplasty failed in 18 patients. Six were managed medically and survived, 7 survived emergency coronary bypass surgery at a nearby facility, and 5 died. The overall mortality rate was 13%. No facilities for open-heart surgery were available at our hospital; however, surgical back-up was available at another hospital, 0.5 miles away. No death was related to the transfer of a patient or to the unavailability of an in-house cardiac surgery facility. The American College of Cardiology/American Heart Association Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures has written guidelines for cardiac surgical back-up for percutaneous transluminal coronary angioplasty. These guidelines strongly recommended that an experienced cardiovascular surgical team be available for emergency surgery in the institution as a back-up for all angioplasty procedures. Our study shows, however, that with careful case selection, emergency angioplasty for acute myocardial infarction can be performed safely with good results in a setting without on-site cardiac surgery facilities.

Aged↗

PubMed1992

Over-expression of c-src or v-src in bone marrow stromal cells stimulates hematopoiesis in long-term bone marrow culture.

The S17 murine stromal cell line was infected with retroviral vectors encoding the v-src and c-src oncogenes and cells expressing high levels of either pp60v-src or pp60c-src were isolated. Long-term bone marrow cultures (LTBMCs) established with these different stromal cell lines showed that progenitor cells proliferated to a greater extent in cultures with stromal cells that over-expressed either c-src or v-src. An increase in the number of granulocytes, monocytes, and colony-forming units granulocyte-macrophage (CFU-GM) in the nonadherent cell population of LTBMCs prepared with S17/v-src or S17/c-src stromal cells was observed. Conditioned media from the S17/v-src and S17/src stromal cell lines stimulated the formation of CFU-GM in the absence of additional hematopoietic cell growth factors. Conditioned media from S17/v-src and S17/c-src stimulated proliferation of the granulocyte-macrophage colony-stimulating factor (GM-CSF)-responsive cell line FDCP-1 and this stimulation was inhibited by neutralizing antisera to murine GM-CSF. An increase in the concentration of GM-CSF was confirmed by enzyme-linked immunosorbent assay. No secretion of interleukin-1 alpha (IL-1 alpha) or tumor necrosis factor-alpha was detected by any of the stromal cell lines. There was no increase in the secretion of either CSF-1 or IL-6 by either S17/v-src or S17/c-src. The addition of 1 micrograms/mL monoclonal anti-GM-CSF antibody to LTBMCs caused a decrease in the number of nonadherent cells in cultures established with each of the different stromal cell lines. Northern blot analysis showed no difference in the level of GM-CSF RNA among the different stromal cell lines. These studies suggest that the increased proliferation of hematopoietic progenitor cells in LTBMCs with S17/v-src or S17/c-src cells may result from a posttranscriptional event that elevates production of GM-CSF by the S17/c-src and S17/v-src stromal cells.

3T3 Cells↗