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S M Watt

Publications and source records attributed to S M Watt.

69 records · Page 4Linked to original sources
PubMed1984

Haemopoietic progenitor cell heterogeneity revealed by a single monoclonal antibody, YW 13.1.1.

Rapid segregation and purification of haemopoietic progenitor cells by simple methods is necessary for a proper analysis of the control of early haemopoiesis. In this paper we describe the use of a rat monoclonal antibody, YW 13.1.1, for that purpose. This reagent reacts with more than 90% of foetal liver cells but spares stem cells. A single-step lysis with antibody and complement achieves a tenfold enrichment for early progenitor cells. The marker also shows an increasing level of expression on the three defined subsets of erythroid progenitor cells. This parallels their developmental pathway and erythropoietin responsiveness. Simple quantitative considerations therefore permit separation of cells at different stages of erythropoiesis.

Animals↗
PubMed1984

Effects of four taurine-conjugated bile acids on mucosal uptake and lymphatic absorption of cholesterol in the rat.

The importance of the bile acid structure on mucosal uptake and lymphatic absorption of cholesterol was investigated using four different taurine-conjugated bile acids. Pure synthetic conjugates of a trihydroxy bile acid, taurocholate, and three dihydroxy bile acids, tauroursodeoxycholate, taurochenodeoxycholate, and taurodeoxycholate were used to completely solubilize [14C]cholesterol and polar lipids for steady rate intraduodenal infusion for 8 hr in bile fistula rats. Lymph output and esterification of [14C]cholesterol and endogenous cholesterol were measured in hourly samples. A second group of bile fistula rats was given the same bile acids as the first group but without added cholesterol or other lipid, i.e., fasting lymph fistula group. Mucosal uptake of [14C]cholesterol was studied using recovery of [14C]cholesterol from lumen and mucosa after 1-hr infusions in conscious bile fistula rats. Lymph output of [14C]cholesterol was promoted more rapidly with taurocholate than with the dihydroxy conjugates and [14C]cholesterol output differed for the three groups given dihydroxy bile acids. The mass of cholesterol in lymph, measured chemically, varied in parallel with [14C]cholesterol absorption. For fasting lymph, infusion of dihydroxy bile acids failed to produce a significant change in endogenous cholesterol output when compared with rats given saline only. Taurocholate infusion markedly increased endogenous cholesterol in lymph of fasted rats. Under all conditions where cholesterol output was stimulated, the increase could be accounted for mainly as esterified cholesterol. Mucosal uptake of [14C]cholesterol during 1-hr infusions in conscious bile fistula rats was slower with the dihydroxy bile acids than with taurocholate. The results indicate the marked effect of the number and configuration of the hydroxyl groups on the solubilizing bile acid for cholesterol absorption.

Absorption↗
PubMed1983

The characterisation of monoclonal antibodies against haemopoietic cells: comparison of an immunoperoxidase method with fluorescence activated cell sorting.

Nucleated cells from normal human peripheral blood and bone marrow have been analysed with 2 rat monoclonal antibodies of known specificity, one (YAML 555.6.6) directed against the P28,33 complex (anti-HLA-DR), and the other (YAML 501.4.4) directed against leucocyte common antigen (anti-LCA). The patterns of reactivity with an indirect immunoperoxidase method on fixed smeared cells were in close agreement with those obtained with a fluorescence activated cell sorter. A further new monoclonal antibody of unknown antigen specificity (YAML 537.2) reacts with an intracellular antigen present in neutrophils and their precursors from the promyelocyte stage onwards, megakaryocytes, and a proportion of monocytes, but not with eosinophils, nucleated red cells or lymphocytes. This reactivity could not be demonstrated using the fluorescence activated cell sorter. The immunoperoxidase method allows the identification of individual positive and negative cells and therefore provides a method of identifying minor reactive and non-reactive cell populations in a heterogeneous cell sample such as normal bone marrow. Cytoplasmic binding sites can be differentiated from membrane binding.

Animals↗
PubMed1983

Removal of T cells from bone marrow for transplantation. Comparison of rat monoclonal anti-lymphocyte antibodies of different isotypes.

We describe a family of six rat monoclonal antibodies which appear to recognize identical or closely related determinants present on virtually all mature human lymphocytes and monocytes, but absent from other blood cells including myeloid and erythroid colony-forming cells. Four IgM antibodies and one IgG2a fix human complement; one IgG2c antibody does so only poorly. All of the antibodies react with lymphocytes from baboons, rhesus and cynomolgus monkeys. However, in all baboons and rhesus monkeys tested, and some cynomolgus monkeys, they also recognize red cells. Nevertheless, in other cynomolgus monkeys reactivity is with lymphocytes only, so these animals will be suitable models for testing the effects of the antibodies in vivo. The antibodies described here could be useful for in vitro removal of lymphocytes from allogeneic marrow grafts (to prevent graft-versus-host disease) or malignant lymphoid cells from autologous grafts (for treatment of leukaemia) and may also find application as general immunosuppressants and for immunotherapy of leukaemia.

Animals↗
PubMed1983

Selective isolation of murine erythropoietin-responsive progenitor cells (CFU-E) with monoclonal antibodies.

Erythropoietin-responsive progenitor cells (CFU-E) from normal mouse foetal liver have been substantially purified on the basis of their differential binding to two monoclonal antibodies in conjunction with flow cytometry. This has allowed the formal identification of the foetal liver CFU-E as an early erythroid blast cell with a highly basophilic cytoplasm. It has also been possible to show a quantitative association of a membrane marker with proliferative potential within a single differentiation lineage. This is the first demonstration of such an association. Progenitor cells enriched in this way should allow study of the molecular mechanisms of erythropoietin action and also serve as a target for determining the cellular specificity of erythroid-transforming viruses.

Animals↗
PubMed1981

High-resolution two-dimensional electrophoretic analysis of acidic, basic and surface proteins of mouse neutrophils.

The proteins from murine neutrophils have been examined using isoelectric focusing and non-equilibrium pH gradient electrophoresis in the first dimension and sodium dodecyl sulfate-polyacrylamide electrophoresis as a second dimension. The major protein, actin, dominates the protein profiles and it appears to be one of the few proteins being synthesised rapidly. In the presence of protease inhibitors, neutrophil (a homogeneous, non-dividing cell population) lysates gave extremely reproducible two-dimensional electrophoretic patterns both with Coomassie blue staining (approx. 20 proteins detected) and with fluorography or autoradiography after [35S]methionine biosynthetic labelling (approx. 450 proteins detected between pH 4 and 7). Biosynthetic labelling was more sensitive than protein staining for some components, although the mature neutrophils did not synthesis certain cellular proteins (e.g., granule proteins such as lactoferrin). Surface labelling of neutrophils (as indicated by the absence of 125I associated with actin) yielded more than 20 major 125I-labelled proteins on high-resolution electrophoretic maps. The major 125I-labeled protein (Mr approximately 90 kdalton) focused at the acidic end of the gels near pH 4.1. This protein could also be detected after [35S]methionine biosynthetic labelling. All of the high molecular weight components focused over a broad pH range (0.2 pH units). At lease one of the surface components appeared to consist of several discrete charge entities.

Actins↗
PubMed1981

The effect of pancreatic diversion on lymphatic absorption and esterification of cholesterol in the rat.

Lymph fistula rats with either biliary fistula or pancreaticobiliary fistula were used to measure coenzyme A-independent mucosal cholesterol esterifying activity in the presence and absence of pancreatic exocrine secretion. Efficiency of pancreatic diversion was verified to minimize contamination of mucosal homogenates with adherent luminal enzyme. The synthetic activity of cholesteryl ester hydrolase (E.C. 3.1.1.13) was measured directly in mucosal homogenates. Indirect evidence for mucosal esterifying activity was obtained from hourly cholesteryl ester output into lymph when other factors known to affect cholesterol absorption were controlled. Rats infused intraduodenally at a constant rate with different concentrations of bile salts, polar lipid, and [3H]cholesterol showed that the infused [3H]cholesterol was absorbed and esterified with equal efficiency in the presence and absence of pancreatic flow. Total lymph output of free and esterified endogenous cholesterol was slightly less efficient in the pancreaticobiliary fistula group (85% of bile fistula values) but percent esterification was the same for both groups. Infusion of lipid-free micellar bile salts separately from other bile components produced a highly significant increase in absorption and esterification of lymph cholesterol for both groups. No correlation was found between cholesterol esterifying activity in a) the lumen or b) the mucosa, and cholesteryl ester output into lymph. The present study suggests an alternative enzyme dependent directly or indirectly on the presence of micellar bile salts in the lumen to explain intestinal cholesterol esterifying activity during absorption.

Acyltransferases↗
PubMed1980

Isolation of mouse bone marrow neutrophils by light scatter and autofluorescence.

Murine bone marrow and blood cells have been analyzed and fractionated using an automated FACS II cell sorter. Using visible light scattered in the direction of (0 degrees) and perpendicular to (90 degrees) the laser beam it was possible to enrich for neutrophils (84%), immature myeloid cells (47%), and monocytes (78%). The enrichment for neutrophils was improved to 92% by using the light scattered by ultraviolet laser light (ca.360 nm). The autofluorescence at these wavelengths proved useful for obtaining further enrichment (to 97%). Indeed, three parameter sorting with 0 degrees and 90 degrees light scatter as well as autofluorescence also allowed the separation of lymphocytes (95%) and immature myeloid cells (89%). The same procedures could be applied for the isolation of neutrophils from mouse peripheral blood.

Animals↗
PubMed1980

Preparation and surface labeling of murine eosinophils.

Eosinophilic polymorphonuclear leukocytes were isolated from the peritoneal cavity of BALB/c mice infected with the parasite Mesocestoides corti. Approximately 4 X 10(7) eosinophils (purity, 50%) could be harvested from each mouse. A high yield and purity of eosinophils was obtained from the peritoneal cells of infected male BALB/c mice using density centrifugation on a gradient of slightly hypotonic colloidal silica sol (Percoll). After initial irradiation of the mice to lower the lymphocyte contamination, subsequent density gradient (and where necessary sedimentation velocity) centrifugation yielded 10(8) eosinophils (purity > 95%) from six to eight mice. It was also possible to isolate small numbers of eosinophils (2 X 10(4) cells/minute, purity > 99%) without irradiating the mice. This could be achieved by separating the density gradient purified peritoneal cells by light-scatter on a Becton-Dickinson cell sorter (FACS II). Analysis of proteins extracted from eosinophils using polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed a group of high molecular weight proteins (bwtween 250K and 160K) which were not as distinctive in the neutrophil profile. Surface labeling was performed, before the cell separation by using 125I and 1,3,4,6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril. Only five 125I-labeled proteins were detected initially (all with apparent molecular weights > 50,000). No 125I appeared to be associated with actin under the conditions used for surface labeling. Four of the eosinophil surface labeled proteins corresponded to surface labeled proteins on neutrophils, but the major surface component of the eosinophils (MW 79,000) appeared to be smaller than the major neutrophil protein (MW 90,000).

Animals↗
PubMed1979

Isolation and surface labeling of murine polymorphonuclear neutrophils.

Methods for the induction of an exudate of polymorphonuclear neutrophilic leukocytes (PMN) in the peritoneal cavity of C57BL, BALB/c, SJL and CBA mice were analysed. Peritoneal exudates in male mice were highly enriched for PMN (80-90%) three hours after a single injection of calcium caseinate whereas eosinophils comprised less than 1% of the exudate population. Female mice were a less satisfactory source of PMN because the proportion of eosinophilis in the exudate was variable. Purification of PMN from peritoneal exudate cells was performed on the basis of light scattering using a Becton-Dickinson cell sorter or by density gradient centrifugation with graded polyvinylpyrrolidone-coated silica particles (Percoll). Both techniques yielded approximately 97% pure PMN preparations. Electrophoretic analysis of the PMN proteins revealed an abundance of lactoferrin and actin, but several other proteins were also present in high concentrations. Proteolytic degradation of several high molecular weight proteins (greater than 90,000) was prevented by the addition of phenylmethylsulphonyl fluoride (PMSF) and ethylene diamine tetracetic acid (EDTA). Surface iodination, using diphenyl, tetrachloroglycouril (IODO-DEN), indicated that there were six tyrosine-containing proteins present on the external cell membrane. The apparent molecular weights of these surface proteins ranged from 185,000 to 90,000 and the major 125I-labeled protein had an apparent molecular weight of 90,000. Neither actin nor lactoferrin was labeled with 125I unless cell viability was lost during the iodination procedure. Standard conditions for labeling the cell surface only, required low iodide and IODO-GEN concentrations. Biosynthetic labeling of PMN using S-methionine increased the sensitivity of detection for most of the proteins, but some of the granule storage proteins (such as lactoferrin) were not effectively labeled within three hours.

Animals↗
PubMed1978

Regulation of hemopoietic cell differentiation and proliferation.

Differentiation and proliferation of almost all hemopoietic cell lines can now be studied in vitro. Cloning techniques and suspension cultures allow the study of proliferation of the multipotential hemopoietic progenitor cell and the committed progenitors for granulocytes, macrophages, eosinophils, megakaryocytes, and erythrocytes. The proliferation of each of the committed progenitor cells is controlled by specific glycoproteins and two of these have recently been purified: granulocyte-macrophage colony-stimulating factor (GM-CSF) and erythropoietin. The rate of proliferation of the GM-progenitor cells and their pattern of differentiation depends on the concentration of the hormone. At low concentrations of GM-CSF (10(-11) M) fewer progenitor cells are stimulated and macrophage colonies rather than granulocyte colonies develop. The change in the direction of granulocyte-macrophage differentiation appears to be related to a) the concentration of GM- CSF and b) the different sensitivity of a subpopulation of monocyte colony-forming cells which are responsive to GM-CSF even at low concentrations of the regulator. Analysis of the rate of RNA synthesis by bone marrow cells has shown that GM-CSF stimulates the mature nondividing end cells of differentiation (ie, polymorphs) as well as the progenitor cells. Although GM-CSF and erythropoietin have been radiolabeled, binding studies have been hampered by the loss of biologic activity during the labeling procedure and the heterogeneity of the target cells to which the regulators bind. Surface proteins and receptors for erythrocytes have been well characterized but the relationships between these proteins and the cell surface proteins of nucleated blood cells is not well understood. It appears that some proteins are lost from the cell surface during the development of granulocytes, which are retained on the surface of the B lymphocyte. Other proteins such as chemotactic receptors and complement receptors only appear on the mature cells. External radiolabeling of the granulocyte surface using iodogen yielded a simple profile of 125I-labeled proteins when analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis.

Cell Differentiation↗
PubMedDate not supplied

Compartmentalization of a haematopoietic growth factor (GM-CSF) by glycosaminoglycans in the bone marrow microenvironment.

Haematopoietic progenitor cells proliferate and mature in semisolid media when stimulated by exogenous haematopoietic cell growth factors (HCGFs) such as granulocyte-macrophage colony-stimulating factor (GM-CSF). They also proliferate in association with marrow-derived stromal cells although biologically active amounts of HCGFs cannot be detected in stromal culture supernatants. It is possible that HCGFs are synthesized in small amounts by stromal cells but remain bound to the stromal cells and/or their extracellular matrix (ECM). This interpretation accords with haematopoietic progenitor cell proliferation in close association with stromal layers in long-term cultures. Glycosaminoglycans (GAGs) are found in the ECM produced by stromal cells. They are prime candidates for selectively retaining HCGFs in the stromal layer; they influence embryonic morphogenesis and cyto-differentiation and they may regulate haematopoiesis. We now report that granulocyte-macrophage colony-stimulating activity can be eluted from cultured stromal layers and that exogenous GM-CSF binds to GAGs from bone marrow stromal ECM. Selective compartmentalization of HCGFs in this manner may be an important function of the marrow microenvironment and may be involved in haematopoietic cell regulation.

Animals↗
PubMedDate not supplied

The specificity of bile salts in the intestinal absorption of micellar cholesterol in the rat.

1. Two aspects of cholesterol absorption; (a) the importance of solubilization and (b) the effects of different bile salts on the mucosal metabolism and lymphatic output of cholesterol, have been investigated using two different in vivo techniques. 2. Bile diverted lymph fistula rats were infused intraduodenally at a steady rate with a constant lipid mixture containing labelled cholesterol, labelled oleic acid and mono-olein. The lipids were completely solubilized in either bile salts or a non-toxic non-ionic detergent, Pluronic F68. Labelled fatty acid was efficiently absorbed from either micellar infusate but virtually no labelled cholesterol appeared in the lymph in the absence of bile salts. 3. Short-term perfusions of the intestine of anaesthetized rats with the same micellar perfusates as above showed approximately 20% of the labelled cholesterol in the mucosa after 30 min perfusion with the bile salt micellar solutions. When the non-ionic micelles were used virtually no isotopic cholesterol left the lumen. 4. Mucosal uptake of labelled cholesterol was linearly dependent on the concentration of solubilized cholesterol in the perfusate and was not dependent on the bile salt concentration. 5. After 30 min the total amount of perfused isotopic cholesterol was recovered from either the lumen or the mucosa, but some fatty acid appeared to have been transported away from the mucosa by this time. 6. The initial rate of mucosal uptake of labelled cholesterol was similar from micellar perfusates using either taurocholate, taurodeoxycholate or taurofusidate. In contrast, after 8 h of infusion, lymphatic output of labelled cholesterol was markedly greater with taurocholate. 7. The increased lymph output with taurocholate was associated with an increase in the esterified fraction of both labelled and unlabelled cholesterol. Fatty acid was absorbed and esterified equally from all three types of perfusate. 8. These results suggested that for the first step in cholesterol absorption, viz. uptake from the lumen, solubilization by a planar detergent was essential. After uptake, the more rapid transfer of cholesterol to lymph in the presence of trihydroxybile acids appeared to be related to a more efficient esterification of cholesterol, but not to a more efficient resynthesis of triglyceride, the other major component of lymph chylomicrons.

Adsorption↗