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Biomedical subjects

D Anderson

Publications and source records attributed to D Anderson.

At least 451 records · Page 25Linked to original sources
PubMed1989

Interleukin-3, GM-CSF, and G-CSF receptor expression on cell lines and primary leukemia cells: receptor heterogeneity and relationship to growth factor responsiveness.

Recombinant human granulocyte-macrophage (GM) colony-stimulating factor (GM-CSF), G-CSF, and interleukin-3 (IL-3) labeled with 125I were used to study the characteristics and distribution of receptors for these factors on in vitro cell lines and on cells from patients with acute nonlymphocytic leukemia (ANL) and acute lymphocytic leukemia (ALL). Receptors for GM-CSF and G-CSF were restricted to a subset of myelomonocytic cell lines whereas IL-3 receptors were also found on pre-B- or early B-cell lines. Receptors for all three CSFs were broadly distributed on ANL cells, with considerable variability in levels of expression. Measurement of the colony-forming ability of ANL cells in response to the CSFs showed that there was no direct correlation between the ability of the cells to respond to a growth factor and the absolute number of receptors expressed for that growth factor. Binding of radiolabeled IL-3 and GM-CSF to ANL cells produced complex biphasic curves. Further analysis showed that both IL-3 and GM-CSF were able to partially compete for specific binding of the heterologous radiolabeled ligand to cells from several ANL patients, suggesting that heterogeneity may exist in human CSF receptors. These results provide new insights into the complex role that CSFs may play in ANL.

Cell Division↗
PubMed1989

Different agonist-receptor active conformations for rat brain M1 and M2 muscarinic receptors that are separately coupled to two biochemical effector systems.

In dissociated cellular preparations of adult rat cortex, M1 and M2 muscarinic receptors were shown to mediate phosphoinositide metabolism and cAMP inhibition, respectively. Additionally, in dissociated striatum, an M2 receptor was shown to inhibit the level of cAMP. The components of "receptor reserve" in these three receptor-effector systems were evaluated by the method of partial receptor inactivation and the dissociation constants for the full agonist carbachol were determined. In dissociated cellular preparations of cortex, and in the presence of 10 mM lithium ion, carbachol (EC50 = 116 microM) activated an M1 receptor subtype (atropine Ki = 0.9 nM; pirenzepine Ki = 9.3 nM) to elicit up to a 7-fold release over the basal level of [3H]inositol 1-phosphate. Carbachol was 100-fold more potent (EC50 approximately 1 microM) in the inhibition of forskolin-elevated [3H]cAMP levels in both the cortex (maximally 28%) and striatum (maximally 49%). Pirenzepine blocked the [3H]cAMP inhibition responses to carbachol in cortex and striatum with Ki values of 334 nM and 313 nM, respectively, which indicated that cortical and striatal M2 receptors mediate [3H]cAMP inhibition. The equilibrium dissociation constants for the full agonist carbachol in mediating these two biochemical responses were determined after partial receptor inactivation with propylbenzilylcholine mustard. The results indicate that cortical M1 receptor-mediated phosphoinositide metabolism is elicited by carbachol through a low affinity agonist-receptor complex (carbachol Kd = 90 microM). However, the cortical and striatal M2 receptor-mediated inhibition of [3H]cAMP is mediated by a high affinity agonist-receptor complex (carbachol Kd = 8.5 microM and 2.9 microM, respectively). Thus, the agonist is bound in a low affinity active conformation of the M1 receptor but the agonist is bound in a high affinity active conformation of the M2 receptor. In contrast to the cortical M1-phosphoinositide system, the central M2 receptors exhibited a significant receptor reserve in their mediation of [3H]cAMP inhibition, as elicited by the full agonist carbachol. Whereas the ratio of Kd/EC50 for carbachol was 0.9 at the cortical M1 receptor, this ratio was 9.4 and 3.2 at the cortical M2 and striatal M2 receptors, respectively.

Animals↗
PubMed1989

Characterization of the striatal M2 muscarinic receptor mediating inhibition of cyclic AMP using selective antagonists: a comparison with the brainstem M2 receptor.

Pharmacological profiles of the striatal and brainstem M2 receptors were developed with a group of selective muscarinic antagonists. The striatal M2 muscarinic receptor was identified by its inhibition of [3H]cyclic AMP levels, whereas the brainstem M2 receptor was characterized using competition with [3H]quinuclidinyl benzilate binding. The potency of pirenzepine does not differentiate clearly between the striatal M2 receptor (Ki approximately 300 nM) and the brainstem M2 receptor (Ki = 219 nM) or peripheral M2 receptors. In the present study, we used 4-diphenylacetoxy-N-methylpiperidine methbromide, hexahydrosiladifenidol, AF-DX 116 and methoctramine to characterize the striatal and brainstem M2 receptors in more pharmacological detail. For comparison, the potencies of these antagonists were also measured at cortical M2 receptors (using competition with [3H]pirenzepine binding). The potencies of 4-diphenylacetoxy-N-methylpiperidine methbromide (KB = 0.19 nM) and hexahydrosiladifenidol (KB = 14 nM) in blocking the striatal M2 receptor suggested similarity to those M2 receptors localized in certain smooth muscles or in glands. However, AF-DX 116 (KB = 155 nM) and methoctramine (KB = 47 nM) were considerably more potent in blocking the striatal M2 receptor than as reported in functional studies in smooth muscle or glands. Thus, the profile of the striatal M2 receptor obtained with these antagonists did not match in all respects with either glandular (probable M4 gene product) or cardiac (probable M2 gene product) muscarinic receptors. In contrast, our data with the brainstem M2 receptor was highly correlated (r = 0.93) with literature data regarding the cardiac muscarinic system.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Polymethylmethacrylate-induced release of bone-resorbing factors.

A pseudomembranous structure that has the histological characteristics of a foreign-body-like reaction invariably develops at the bone-cement interface in the proximity of resorption of bone around aseptically loosened cemented prostheses. This study was an attempt to implicate polymethylmethacrylate in this resorptive process. Unfractionated peripheral-blood mononuclear cells (consisting of lymphocytes and monocytes) and surface-adherent cells (monocyte-enriched) were prepared from control subjects who did and did not have clinical evidence of osteoarthrosis and from patients who had osteoarthrosis and were having a revision for failure of a cemented hip or knee implant. Cells were cultured for varying periods in the presence and absence of nonpolymerized methacrylate (one to two-micrometer spherules), pulverized polymerized material, or culture chambers that were pre-coated with polymerized cement. Conditioned media that were derived from both methacrylate-stimulated cell populations were shown to contain specific bone-resorbing mediators (interleukin-1, tumor necrosis factor, or prostaglandin E2) and to directly affect bone resorption in 45Ca-labeled murine limb-bone assays.

Animals↗
PubMed1988

Cholesteryl ester accumulation in smooth muscle cells after uptake of necrotic products from atherosclerotic lesions.

Cholesterol-ladened plasma membrane vesicles were used to load smooth muscle cells (SMC) with cholesterol. Plasma membrane vesicles (PMV) were isolated from rabbit atherosclerotic lesions, and characterized as to size, cholesterol content, and marker enzyme (plasma membrane, lysosome, endoplasmic reticulum) composition. PMV were regarded as a necrotic product since they are produced upon injury to cells. Degradation of PMV was proportional to the PMV protein concentration in the culture medium, suggesting bulk intake of PMV. Cholesterol accumulation of SMC varied with the cholesterol content of the vesicle. Incubation for 3 days with PMV having 0.39 and 0.62 mg cholesterol/mg protein induced the accumulation of 8 and 29 micrograms of esterified cholesterol/mg cell protein, respectively. Incorporation of oleate into cholesteryl ester during a 24-hr period under these conditions, however, was the same. The contribution of cholesterol ester synthesis to the esterified cholesterol content of SMC was 40 and 11% of the total when exposed to PMV having, respectively, low and high contents of cholesterol. This study suggests that cholesterol-bearing PMV in lesions can be utilized to load lesion-SMC. These observations suggest that lipid-bearing elements other than low density lipoprotein may be responsible for cholesterol-loaded SMC in lesions.

Animals↗
PubMed1988

Human macrophage-colony stimulating factor: alternative RNA and protein processing from a single gene.

Macrophage-colony stimulating factor (M-CSF, CSF-1) has been reported to be required for the proliferation and differentiation of macrophages from hematopoietic progenitor cells. Recently, two human M-CSF cDNA clones were isolated encoding proteins of 256 and 554 amino acids. We report here the isolation of a third M-CSF cDNA that encodes a protein of 438 amino acids. The coding regions for the three cDNA clones share a common amino-terminus of 149 amino acids and a common carboxyl-terminus of 75 amino acids including a membrane spanning region. In addition, we isolated a genomic clone of human M-CSF. When each of the cDNA clones or the genomic clone were transfected into COS-7 monkey kidney cells, biologically active M-CSF was expressed as judged by the ability of transfected cell supernatants to stimulate proliferation and colony formation of murine bone marrow cells, as well as formation of monocytic colonies from human bone marrow cells. Surprisingly, proliferation of human bone marrow cells was not induced by recombinant human M-CSF. Analysis of the M-CSF proteins released by COS-7 cells revealed that monomer subunit proteins of 44 or 28 kDa were produced. In addition, we found that the membrane spanning region, present in all three forms of M-CSF cDNA, was not required for the synthesis of a biologically active protein. However, when the membrane spanning region was present in the three M-CSF cDNAs, cell surface associated forms of M-CSF could be readily detected.

Animals↗
PubMed1988

Chromosome aberrations, mitogen-induced blastogenesis and proliferative rate index in peripheral lymphocytes from 106 control individuals of the U.K. population.

Blood samples were taken from 106 individuals (73 males and 33 females) and examined for chromosome aberrations, mitogen-induced blastogenesis and proliferative rate index (PRI). The values obtained were investigated in relation to sex, age, smoking, alcohol consumption and X-ray exposure. In all the parameters, there was shown to be a difference between the mean values for the males and females. The incidence of chromosome aberrations was greater in females than in the males, whereas the mean values of PRI and mitogen-induced blastogenesis were lower in females than in the males. A sex difference has been reported previously in the same population, in that the females were shown to have a higher rate of sister-chromatid exchanges than the males (Anderson et al., 1986; Dewdney et al., 1986). Contraceptive pill usage was not considered to be of importance in the sex difference seen and there was shown to be no significant influence due to age, smoking or alcohol consumption on any of the parameters except that smoking reduced lymphocyte PRI. Males with previous X-ray exposure also showed a lower response to mitogen-induced blastogenesis and had a reduced PRI.

Age Factors↗
PubMed1988

Genotoxic effects in peripheral blood and urine of workers exposed to low level benzene.

Blood samples were obtained from a population of refinery workers representing different age groups. Sixty six men with low average exposure to benzene and 33 male controls were investigated. An examination of cell cycle kinetics and sister chromatid exchange was carried out on control and exposed individuals. No significant differences were found between groups of individuals varying in their drinking and smoking habits or their exposure to diagnostic x rays. Individuals with the lowest and highest phenol values were examined for urine mutagenicity, with urinary phenol used here as an indicator of benzene exposure. There was no difference in the number of revertant colonies in strains TA98 and 100 between the high and low urinary phenol groups. There were also no differences in any of the biochemical measures or haematological parameters investigated in all the individuals except that higher values for mean corpuscular volume were found in exposed than in control individuals. These values, however, were within the normal clinical range.

Adult↗
PubMed1988

Effects of methyl isocyanate on rat muscle cells in culture.

Since the Bhopal disaster, in which the causal agent was methyl isocyanate (MIC), exposed people have complained of various disorders including neuromuscular dysfunction. In an attempt to gain some information about the response of muscle tissue to MIC its effects were investigated in cells in culture isolated from muscle of 2 day old rats. After treatment with a range of MIC concentrations (0.025-0.5 microliter/5 ml culture) the total number of nuclei of the two main cell types (fibroblasts and myoblasts) and the number of nuclei in muscle fibres (myotubes) were recorded. At lower doses which had little effect on the total number of nuclei, the formation of muscle fibres--that is, fusion of muscle cells--was prevented as the proportion of nuclei in myotubes was decreased. At higher doses both cell types were killed. This would suggest either an effect on muscle differentiation or a selective toxicity towards myoblasts. The observations were supported by light and electron microscopy.

Animals↗
PubMed1988

Effect of occupational exposure to benzene on phytohaemagglutinin (PHA) stimulated lymphocytes in man.

This study was carried out to investigate the effects of potential low level exposure to benzene on phytohaemagglutinin (PHA) stimulated lymphocytes. Sixty six male workers of a refinery population were studied and compared with 33 control workers in the same refinery who were not known to have been exposed to benzene. The responsiveness of the lymphocyte to PHA as a measure of blastogenesis was measured by the incorporation of radio labelled thymidine by the stimulated lymphocytes in vitro. Questionnaires were used to determine various lifestyle factors such as smoking, drinking, and exposure to ionising radiation. The results showed that there was no difference between the exposed group (mean 28928 + 1524 SE (decays per minute (DPM] as compared with the control group (mean 28304 + 2483 SE DPM). Furthermore, it was not possible to determine any effects attributable to various social factors. There was, however, a suggestion of a decrease in mitogenic response with age in both exposed and control workers that was consistent with other studies. It has been shown that products of benzene metabolism may affect the mitogenic response of lymphocytes in a similar way to known promoting agents. This study was unable to show these effects, probably as a result of the low exposures encountered by the individuals.

Adult↗
PubMed1988

Chromosomal aberrations and sister chromatid exchanges in lymphocytes and urine mutagenicity of migraine patients: a comparison of chronic feverfew users and matched non-users.

1. Thirty migraine patients who had taken the leaves, tablets or capsules of feverfew daily for more than 11 consecutive months were compared to 30 feverfew non-user migraine patients who had been individually age- and sex-matched. 2. The frequency of chromosomal aberrations and sister chromatid exchanges (SCE) were determined from lymphocyte cultures established from blood samples taken over a period of several months. Matched pairs were sampled on the same date for two-thirds of the cases, and the greatest difference in sampling time of the remainder was 20 days. Also, the mutagenicity of urine samples from 10 feverfew user migraine patients was compared to that from 10 matched non-user migraine patients using the Ames Salmonella mutagenicity test system. Paired samples were given on the same date. 3. The mean frequency of chromosomal aberrations in the feverfew user group was lower than that in the non-user group both in terms of cells with breaks (2.13% vs 2.76%) and in terms of cells with all aberrations (4.34% vs 5.11%). However, this difference was small and not significant. 4. The mean frequency of SCE in the feverfew exposed group was lower than that in the control group (8.78 vs 8.80 SCE/cell), but, this difference was not significant as determined by factorial analysis of variance (P = 0.897). There was a highly significant variance between the frequencies of SCE in the matched pairs of migraine patients but this was not related to age, sex or feverfew exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Characterization of lymphocyte stimulation by phorbol related compounds.

1. The stimulation of (3H)-thymidine incorporation by lymphocytes in response to phorbol and seven other phorbol related compounds was investigated. 2. Lymphocytes from each of a small group of individuals were treated with the test compounds over wide concentration ranges. 3. All the tested compounds, including the most active, 12-0-tetradecanoylphorbol-13-acetate, were far less effective lymphocyte mitogens than the plant lectin phytohaemagglutinin. 4. Inter-individual differences were detected in the maximum response to the phorbols but not in their stimulating potency, as estimated by the concentration producing a half maximal response. 5. The rank order of the lymphocyte stimulating potency of the tested compounds was similar to the rank order of both tumour promoting activity and irritant potency in mouse skin. 6. Lymphocyte stimulation was paralleled equally well by these two mouse skin responses.

Adolescent↗