Biomedical subjects
Publications and source records attributed to R E Williams.
A 65-year-old female with angiotropic B-cell lymphoma is reported. Despite the absence of systemic involvement on formal staging and the favourable response of the cutaneous lesions to triple systemic chemotherapy with prednisolone, vincristine and cyclophosphamide, postmortem findings showed that death was due to widespread disease dissemination.
It has been previously demonstrated that maley-lated-BSA (maleyl-albumin) induces functional activation in murine peritoneal macrophages. Furthermore, maleyl-albumin has been shown to interact with two distinct sites on human monocytes; one site is the scavenger receptor, a 260-kDa oligomeric protein which recognizes modified forms of low density lipoprotein (LDL), and the second is a lower affinity site which has yet to be structurally characterized. In the present study, we wished to quantitatively assess the number and character of maleyl-albumin-binding sites on murine peritoneal macrophages and to determine which site or sites are involved in signaling the macrophage to undergo extensive functional development. Binding studies. demonstrate at least two distinct receptors for maleyl-albumin on murine peritoneal macrophages. Scatchard analyses of the binding isotherms reveal two sites characterized by dissociation constants (Kd) of 17.6 nM and 4.9 microM and maximal binding of 1.2 x 10(5) and 1 x 10(6) sites/cell, respectively. The contribution of the scavenger receptor, determined by binding analyses of malondialdehyde-LDL, is described by two sites with Kd of 39.4 pM and 9.6 nM, and maximal binding of 2.7 x 10(3) and 1.9 x 10(4) sites/cell, respectively. Maleyl-albumin blocks binding of malondialdehyde-LDL, whereas modified LDL fails to inhibit binding of maleyl-albumin. Maleyl-albumin, at concentrations producing lower affinity binding, stimulates tumor cytolysis, expression of mRNA encoding TNF, and suppression of INF-gamma-induced expression of Ia Ag. Malondialdehyde-LDL fails to elicit these responses. We conclude that macrophage activation produced by maleyl-albumin is mediated by interaction with the low affinity, high capacity binding site for maleyl-albumin rather than the scavenger receptor.
Current misalignment mutagenesis models have identified certain sequences such as direct and inverted repeats, which can stabilize transient misalignments on single-stranded DNA, as major structural parameters for deletions. We have constructed derivatives of the plasmid pBR325 to investigate further the relative roles of such sequences under controlled conditions. The plasmid derivatives pOCE15, pRS1 and pRS4, were obtained by cloning fragments of the same approximate size (60-64 bp) but different sequence into the unique EcoR1 site of the chloramphenicol acetyl transferase (cat) gene of plasmid pBR325. The insert of pOCE15 is a perfectly palindromic lac operator fragment. Both pRS1 and pRS4 carry the same non-palindromic fragment but differ from each other in the sequence at the right (3') end of the insert. Plasmid pRS4 differs from pRS1 by a 9-bp duplication containing an additional EcoR1 site at the 3' end of the insert. This arrangement yields overlapping imperfect 17-18 bp and perfect 11 bp direct repeats at the deletion termini and creates multiple opportunities for the stabilization of misaligned intermediates. The deletion rate, measured from the reversion of chloramphenicol sensitivity (Cms) to resistance (Cmr), was always highest in pRS4, intermediate in pOCE15 and lowest in pRS1, with an approximate ratio of 100:10:1. We have also obtained evidence for the participation of RecA in the genesis of deletions in these pBR325-derived plasmids.
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Clear cell acanthomas (Degos' acanthomas) are usually solitary tumours and an excisional diagnostic biopsy therefore provides effective treatment. Such an approach is, however, impractical in the much rarer condition of multiple clear cell acanthomas where up to 30 lesions have been described on one patient. We describe a case of multiple clear cell acanthomas in which cryotherapy provided a quick and convenient method of treatment resulting in minimal scarring especially when compared to excision biopsy.
The contributions of direct immunofluorescence, light microscopy and serology to the investigation of 52 patients with possible lupus erythematosus were studied. Direct immunofluorescence was found to be most valuable in the investigation of possible systemic lupus erythematosus whilst only of supportive value in the investigation of possible chronic discoid lupus erythematosus. The importance of performing light microscopy before direct immunofluorescence in cases of possible chronic discoid lupus erythematosus is shown.
The anaerobic sulfate-reducing bacterium Desulfovibrio desulfuricans was grown on medium supplemented with either Kraft lignin or lignosulfonate. Only lignosulfonate contributed to the growth of D. desulfuricans cells, by replacing sulfate, a natural electron acceptor for this microorganism. Kraft lignin added to the culture medium could not substitute for lactate or sulfate, both necessary culture medium components. However, it was found to enhance the viability of D. desulfuricans cells. When changes occurring in lignin during growth of Desulfovibrio cultures were monitored, it was found that both lignin preparations could be partially depolymerized. Spectrophotometric and elemental analysis of biologically treated lignins suggested that both the polyphenolic backbone and lignin functional groups were affected by D. desulfuricans. After treatment, a twofold increase in the sulfur content of Kraft lignin and a minor decrease (14%) in the sulfur content of lignosulfonate were observed. After biological treatment, Kraft lignin and lignosulfonate both bound larger quantities of heavy metals.
Human granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulates the colony growth of myeloid progenitors in semisolid media, and enhances the function of mature effector cells, including neutrophils, monocytes, and eosinophils. Small cell carcinoma lines (SCCL) have properties of amine precursor uptake and decarboxylation (APUD) cells and express high levels of the enzyme, L-aromatic amino acid decarboxylase. We looked for possible expression of GM-CSF receptors on nonhematopoietic cells and found specific high-affinity binding of human GM-CSF to SCCL and to the SV40-transformed African green monkey kidney cell line, COS. The small cell carcinoma lines responded to GM-CSF with enhanced proliferation, and both small cells and COS cells were found to express authentic 84,000 dalton GM-CSF receptor protein. These findings indicate that nonhematopoietic cells can bind and respond to GM-CSF, suggesting additional biological activities as well as the possibility of tumor responses when GM-CSF is used therapeutically in humans. Since preliminary clinical trials using CSFs as adjunctive treatment in patients with solid tumors are underway, it will be important to consider the possible responsiveness of nonhematopoietic tumor cells to CSFs.
Although its potential is great, the use of aquatic insects in determining submersion intervals at death-scene investigations has not been exploited in the past. Aquatic environments have no known true specific indicator species, as do terrestrial habitats. However, aquatic environmental studies show that organisms may colonize a substrate dependent on factors such as size, position, exposure to current, water temperature, current speed, water depth, the presence of algal communities, or detritus. Certain aquatic insects such as the chironomid midges (Diptera, Chironomidae), and the caddisflies (Trichoptera), are capable of colonizing immersed bodies; and with the known biology of a specific species of insect for a certain geographic area, time intervals of submersion can be established.
During preliminary examination of the body of a homicide victim, a peculiar red "fiber" was noticed and recovered. Initially believing this to be a carpet fiber, the item was subjected to fiber analysis. It was found to be a short coiled particle not like any known natural or synthetic fabric fiber. Subsequent examinations determined this "fiber" to be the larva of a common freshwater midge (Diptera; Chironomidae). Chironomid larvae have been observed on other bodies recovered from freshwater environments. Entomological studies of this organism have led to the conclusion that the presence of chironomid larvae indicates submersion of the body.
Each of four independent experimental approaches showed that human breast carcinoma T47D cells contain both high and low affinity progesterone receptors. (i) Equilibrium-specific [3H]progesterone binding to adherent cultured cells revealed dissociation constants (Kd) of 1.5 and 60 nM and 0.33 and 2.4 X 10(6) sites/cell, respectively. Both the high and low affinity receptors were specific for progestins as demonstrated by steroid binding competition studies conducted at 5 and 50 nM [3H]progesterone. (ii) Equilibrium [3H]progesterone binding to the resolved soluble and particulate fractions from a cell homogenate sedimented at 40,000 X g.min revealed Kd = 1.4 nM high affinity binding sites exclusively in the supernatant fraction and Kd = 24 nM low affinity sites exclusively in the particulate fraction. Extraction of the particulate fraction with a high ionic strength buffer solubilized the low affinity receptors stoichiometrically; but once solubilized, they displayed Kd = 2.4 nM high affinity progesterone binding. Characterizations of 3H-ligand bound specifically to progesterone receptors in intact cells or resolved subcellular fractions revealed no [3H]progesterone metabolites that could account for the low affinity binding. (iii) Calculations based on the rate constants of [3H] progesterone association with or dissociation from adherent cells revealed the same dissociation constants for both high and low affinity binding as those determined by equilibrium measurements. (iv) Nonionic detergent extraction of cells incubated with a wide range of [3H]progesterone concentrations revealed high affinity progesterone binding to receptors in the detergent-soluble fraction and low affinity binding associated primarily with the particulate residue, consistent with the data on equilibrium progesterone binding to resolved cell homogenate fractions. The rate of extraction of the high affinity receptor-progesterone complex with nonionic detergent (t1/2 = 1 min at 0 degrees C) equaled the rate of extraction of a representative lysosomal enzyme, beta-acetylglucosaminidase.
Human granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine derived from activated T cells, endothelial cells, fibroblasts, and macrophages. It stimulates myeloid and erythroid progenitors to form colonies in semisolid medium in vitro, as well as enhancing multiple differentiated functions of mature neutrophils, macrophages, and eosinophils. We have examined the binding of human GM-CSF to a variety of responsive human cells and cell lines. The most mature myelomonocytic cells, specifically human neutrophils, macrophages, and eosinophils, express the highest numbers of a single class of high affinity receptors (Kd approximately 37 pM, 293-1000 sites/cell). HL-60 and KG-1 cells exhibit an increase in specific binding at high concentrations of GM-CSF; computer analysis of the data is nonetheless consistent with a single class of high affinity binding sites with a Kd approximately 43 pM and 20-450 sites/cell. Dimethyl sulfoxide induces a 3-10-fold increase in high affinity receptors expressed in HL-60 cells, coincident with terminal neutrophilic differentiation. Finally, binding of 125I-GM-CSF to fresh peripheral blood cells from six patients with chronic myelogenous leukemia was analyzed. In three of six cases, binding was similar to the nonsaturable binding observed with HL-60 and KG-1 cells. GM-CSF binding was low, or in some cases, undetectable on myeloblasts obtained from eight patients with acute myelogenous leukemia. The observed affinities of the receptor for GM-CSF are consistent with all known biological activities. Affinity labeling of both normal neutrophils and dimethyl sulfoxide-induced HL-60 cells with unglycosylated 125I-GM-CSF yielded a band of 98 kDa, implying a molecular weight of approximately 84,000 for the human GM-CSF receptor.
Human erythroid-potentiating activity (EPA) is a 28,000 mol wt glycoprotein that stimulates the growth of erythroid progenitors in vitro and enhances colony formation by the K562 human erythroleukemia cell line. EPA has potent protease inhibitory activity, and is also referred to as tissue inhibitor of metalloproteinases (TIMP). We observed that colony formation by K562 cells in semi-solid medium containing reduced fetal calf serum (FCS) is not directly proportional to the number of cells plated, suggesting production of autostimulatory factors by K562 cells. Using radioimmunoprecipitation and a bioassay for EPA, medium conditioned by K562 cells was found to contain high levels of biologically active EPA; Northern hybridization analysis confirmed the expression of EPA mRNA. Radiolabeled EPA was used to identify cell surface receptors on K562 cells. Together, these results suggest that EPA may act as an autocrine growth factor for K562 cells.
Incubation of adherent human breast epithelial HBL100 cells with epidermal growth factor (EGF) decreased [3H]dexamethasone binding by 35% with no effect on affinity. Maximal inhibition was obtained at 3 nM EGF and the 50% effective dose was 0.2 nM EGF. Decreased dexamethasone binding induced by 3 nM EGF was maximal by 5 min of treatment and, in the continuous presence of EGF, persisted at a constant level over 4 days. The action of EGF was antagonized by 12-O-tetradecanoylphorbol-13-acetate, which did not inhibit dexamethasone binding significantly, and by concanavalin A. In homogenates of EGF-treated cells, decreased dexamethasone binding was observed only in the cytosolic fraction. Saturation dexamethasone binding inhibited the growth rate of HBL100 cells by approximately 50%, but concurrent treatment with EGF overcame this inhibition. The effect of EGF on dexamethasone-inhibited cell growth also was antagonized by 12-O-tetradecanoylphorbol-13-acetate.
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After combination chemotherapy, 19 patients underwent salvage surgery for testicular neoplasia. Active malignancy was found in nine patients, three of whom have died of the disease. Those with benign residual disease have had a good prognosis without further treatment. Biopsy alone of the residual masses proved reliable in determining which patients were to be simply followed or given further chemotherapy. If active malignancy was not resected fully, the prognosis was very poor. Our policy continues to be to attempt complete excision of residual masses after induction chemotherapy and to give salvage chemotherapy to patients with residual active malignancy.