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Biomedical subjects

A Woods

Publications and source records attributed to A Woods.

At least 145 records · Page 8Linked to original sources
PubMed1985

Characterization of a dermatan sulfate proteoglycan synthesized by murine parietal yolk sac (PYS-2) cells.

A dermatan sulfate proteoglycan has been isolated from a murine parietal yolk sac cell line, which in culture synthesizes basement membrane components. The proteoglycan has a molecular weight of 200,000-300,000 with 10-15 dermatan sulfate chains of Mr = 14,000-16,000. The glycosaminoglycan chains carry sulfate residues predominantly attached to C-4 of the galactosamine unit; less than 10% of the sulfate groups occur as 6-sulfated galactosamine units. About 60% of the uronic acid residues are of the glucuronic configuration, the rest being iduronic acid. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of chondroitinase ABC-treated 125I-labeled proteoglycan reveals two polypeptides with molecular weights of 34,000 and 27,000. Results from papain digestion of the proteoglycan suggest that most of the polysaccharide chains are clustered at a papain-resistant segment of the core protein (Mr = 8,000). This proteoglycan is distinctly different from the large cartilage proteoglycan in the smaller size of its core protein, and its relationship to other small chondroitin and dermatan sulfate proteoglycans and to the chondroitin sulfate proteoglycan recently located in rat tissue basement membranes will be discussed.

Animals↗
PubMed1985

Heparan sulfate proteoglycans of rat embryo fibroblasts. A hydrophobic form may link cytoskeleton and matrix components.

Heparan sulfate proteoglycans (HSPGs) synthesized in cultures of rat embryo fibroblasts have been isolated and characterized. Cells grown in the presence of [35S]sulfate secreted a large amount of radiolabeled macromolecules into the culture medium of which only a small proportion was identified as HSPG. However, the majority of radiolabeled proteoglycans isolated from the cell layer were HSPGs. Here, two types of HSPG were detected. One type had an Mr of 5-8 X 10(5) as estimated by gel chromatography on Sepharose CL-4B in the presence of 0.1% sodium dodecyl sulfate and lacked hydrophobic properties in that it showed no affinity for octyl-Sepharose and could not be inserted into liposomes. The other HSPG type had an estimated Mr of 3-5 X 10(5), was retained on octyl-Sepharose, and could be inserted into liposomes. In addition, the cells contained low molecular weight heparan sulfate oligosaccharides. Treatment of living cells with 0.2% Triton X-100, which retained stress fibers and extracellular matrix but solubilized cell membranes, released a proportion of the smaller HSPG together with the heparan sulfate oligosaccharides. The cytoskeleton-matrix residue remaining after detergent extraction of the cell contained the larger species of HSPG in addition to the smaller HSPG. The presence of the smaller hydrophobic HSPG in the detergent-treated cytoskeleton-matrix preparations suggests that it may form part of a transmembrane cytoskeleton-matrix linkage.

Animals↗
PubMed1985

Distinct functional phenotypes of cloned Ia-restricted helper T cells.

Analysis of activation of phosphorylcholine (PC)-specific B cells by a large number of different cloned, self Ia-specific helper T cell (Th) clones has permitted the classification of such T cells into four distinct functional types. Types 1 and 2 induce B cells to secrete anti-PC antibody in an antigen-specific, Ia-restricted fashion. Type 3 cells induce antigen-specific, Ia-restricted B cell proliferation, but do not lead to specific antibody formation, and have been shown previously to have suppressor functions. Type 4 cells are autoreactive, and induce antigen-independent B cell activation and antibody secretion. The distinction between type 1 and type 2 Th clones was analyzed in detail. In bulk cultures, type 1 cloned lines generate an idiotypically heterogeneous anti-PC antibody response, whereas type 2 cloned lines induce a larger response that is dominated by the T15 idiotype. In limiting-dilution analyses, type 2 cells induce fourfold more T15+, PC-specific precursor B cells than do type 1 cells, and in addition, induce larger burst sizes for T15+, PC-specific B cells. Type 4 clones can also be subdivided into cells that are type 1-like, and cells that are type 2-like. These differences in functional phenotype are seen over a broad range of antigen and cell doses. Detailed analysis of the behavior of these distinct functional types of Th should allow a better understanding of the functional properties of mixed populations of antigen-primed, Ia-restricted Th cells.

Animals↗
PubMed1984

Proteoglycans in basement membranes.

Previous studies have shown that sulphated proteoglycans are integral components of basement membranes. We have used mouse parietal yolk sac cells as a model system for our studies. These cells produce several basement membrane components, including a heparan sulphate proteoglycan and a chondroitin sulphate proteoglycan. The structure of the heparan sulphate proteoglycan has been described previously. The chondroitin sulphate proteoglycan has an Mr of 200 000-300 000 and contains 10-20 chondroitin sulphate chains (Mr = 14 000-16 000), attached to a core protein that on polyacrylamide gel electrophoresis appears as a doublet (with Mr = 34 000 and 27 000). Further structural analysis suggests that the majority of the polysaccharide chains are clustered around one segment of the core protein. The polysaccharide chains carry sulphate residues predominantly attached to C-4 of the galactosamine unit. More than 60% of the uronic acid residues are of the glucuronic configuration, the rest being iduronic acid. The parietal yolk sac cells secrete about equal amounts of the two proteoglycans into the culture medium, whereas heparan sulphate proteoglycan is the predominant proteoglycan found in the extracellular matrix of these cells. This proteoglycan appears to be anchored in the matrix by interactions involving the core protein rather than the polysaccharide chains.

Animals↗
PubMed1984

The effect of storage in liquid nitrogen on the recovery of human dental plaque bacteria.

Centrifuged deposits of various individual bacteria from type-culture collections and dental plaque samples were immersed in liquid nitrogen for periods of up to 2 years. All the organisms were recovered after storage in liquid nitrogen but Fusobacterium nucleatum (ATCC 10953) and Campylobacter fetus (NCTC 10354) consistently showed a reduction in the number of colony-forming units after freezing. The main effect on bacterial proportions in plaque samples was a reduction in aerobic Gram-negative cocci. Thus, storage in liquid nitrogen may be useful for comparative studies of dental plaque and as a means of storing individual organisms.

Adolescent↗
PubMed1984

An investigation of the effects of maltose and sucrose in the diet on the microbiology of dental plaque in man.

In a double-blind cross-over study, 24 dental students consumed 150 g of sucrose or maltose a day in various foods. After 15 days, plaque samples were collected from the distal surface of upper right first premolars; post-diet samples were collected four months later. The median total anaerobic count of plaque exposed to sucrose was significantly lower compared with maltose samples (p less than 0.05). Glucan-producing organisms per 100 anaerobes in the sucrose samples compared with the maltose (p less than 0.05). Streptococcus sanguis and Streptococcus mitior were the most frequently-isolated streptococci.

Adult↗
PubMed1984

The effect of solubilized bone matrix fractions from different mammalian species on glycosaminoglycan synthesis by cultured fibroblasts.

Human and bovine bone matrices were extracted with salt solutions of different composition and the extracts tested for stimulation of incorporation of radioactivity from [3H]glucosamine and [35S]SO4 into the hyaluronic acid and chondroitin sulfate of the cell pellet, the cell surface and the medium fractions of human synovial cells in culture. Stimulatory activity was extracted with a solution of 0.3 M EDTA in 2.5 M NaCl from bovine but not human bone. Subsequent extraction of the residues with 4 M guanidinium hydrochloride yielded activity from both matrices. A major stimulation of incorporation of radioactivity was observed in the cell surface fractions. Human synovial cells constitute a more sensitive assay system for the stimulatory activity than rabbit synovial cells.

Animals↗
PubMed1984

Relationship of heparan sulfate proteoglycans to the cytoskeleton and extracellular matrix of cultured fibroblasts.

The distribution of heparan sulfate proteoglycans (HSPG) on cultured fibroblasts was monitored using an antiserum raised against cell surface HSPG from rat liver. After seeding, HSPG was detected by immunofluorescence first on cell surfaces and later in fibrillar deposits of an extracellular matrix. Cell surface HSPG aligned with microfilament bundles of rat embryo fibroblasts seen by phase-contrast microscopy but was diffuse on transformed rat dermal fibroblasts (16C cells) which lack obvious stress fibers. Focal adhesions isolated from either cell type and monitored by interference reflection microscopy showed a concentration of HSPG labeling with respect to the rest of the membrane. Increased labeling in these areas was also seen for fibronectin (FN) by using an antiserum that detects both plasma and cell-derived FN. Double immunofluorescent staining of fully adherent rat embryo fibroblast cells showed some co-distribution of HSPG and FN, and this was confirmed by immunoelectron microscopy, which detected HSPG at localized areas of dorsal and ventral cell membranes, overlapping cell margins, and in the extracellular matrix. During cell shape changes on rounding and spreading, HSPG and FN may not co-distribute. Double labeling for actin and either HSPG or FN showed a closer correlation of actin with HSPG than with FN. The studies are consistent with HSPG being closely involved in a transmembrane cytoskeletal-matrix interaction; the possibility that HSPG coordinates the deposition of FN and other matrix components with cytoskeletal organization is discussed.

Animals↗
PubMed1984

Human T-cell leukemia virus in cutaneous T-cell lymphoma in Denmark. A possible association of HTLV and aneuploidy.

Cutaneous T-cell lymphomas (CTCL) are neoplasias of mature T-cells and comprise Sezary syndrome, mycosis fungoides and some cases of lymphomatoid papulosis. Clinically this group of disorders differ from the more aggressive neoplasias of mature T-cells known as adult T-cell leukemia/lymphoma and T-cell lymphosarcoma leukemia which are associated with human T-cell leukemia virus (HTLV). We have found that of 68 patients from Denmark with CTCL ten were positive for HTLV antibodies and that the neoplastic T-cells from skin specimens in seven of eight HTLV-antibody positive patients studied by DNA flow cytometry exhibit DNA aneuploidy. Either one or two hyperdiploid cell clones were present. Aneuploidy was found in two patients with histologically verified mycosis fungoides, in four patients with histological non-diagnostic mycosis fungoides, and in one patient with lymphomatoid papulosis. The present data indicate that further seroepidemiologic survey studies of cutaneous T-cell lymphomas should include the early histological non-diagnostic stages, especially when aneuploidy is present.

Adult↗
PubMed1983

Stages in specialization of fibroblast adhesion and deposition of extracellular matrix.

Fibroblast cells seeded on a serum glycoprotein shown previously to mediate a spread shape without focal adhesions or microfilament bundles (Stage 1 spread) are now shown to have substratum contacts in which coated pits are abundant and associated with small globular deposits of glycocalyx bridging to substratum and staining for fibronectin and acidic glycoconjugates. After stimulation with serum or fibronectin to form focal adhesions and microfilament bundles (Stage 2 spread), clathrin-based structures remain at the cell underside but no longer in conspicuously higher concentration than on the dorsal surface; extracellular material at adhesions is now as regular strands which stain for acidic glycoconjugates but (as reported earlier by Chen and Singer) not always for fibronectin. During these stages of adhesion, striking changes are seen in the cellular display of fibronectin monitored by immunofluorescence. In rounded cells this is granular and cytoplasmic, concentrated around the submembranous cortex; on spreading to Stage 1, it remains granular and intracellular but is now oriented strongly towards the lower cell surface; only in Stage 2 does externalisation proceed to deposit fibrillar fibronectin on the substratum. While cytoplasmic orientation of matrix precursors can be determined by cell contact, organised externalisation is therefore coupled to fully developed adhesion status.

Animals↗
PubMed1983

Effect of calcium on the morphology of human platelets spread on glass substrates.

The morphology of human platelets spread on glass substrates is sensitive to the presence of calcium. In the absence of Ca2+, cells spread from buffered salt solution develop radially oriented filopodia and subsequently a broad hyalomere surrounding the central region of the cell from which granules are frequently exocytosed. In the presence of Ca2+ cell rounding and apparent withdrawal from the substrate occurs. Scanning (SEM) and transmission (TEM) electron microscopy of cells rounded in the presence of Ca2+ show fibrous elements connecting the cells to the substratum as well as adherent to the substrate in the vicinity of the rounded cells. Interference reflection microscope (IRM) images of these cells are heterogeneous: some contain small discrete darker regions suggesting the presence of focal specializations at the ventral cell surface. In contrast IRM images of cells spread in the absence of Ca2+ indicate predominantly broad areas of unspecialized contact with the substrate in agreement with TEM observations. These results suggest that Ca2+ may enhance platelet-substrate adhesion by initially promoting the formation of focal specializations which become more pronounced as cell rounding occurs possibly due to Ca2+ activation of an actomyosin-based contractile mechanism.

Blood Platelets↗
PubMed1982

Factors that affect human hemopoiesis are produced by T-cell growth factor dependent and independent cultured T-cell leukemia-lymphoma cells.

Some laboratory results and clinical situations suggest that human T cells may be important in the regulation of growth of hematopoietic cells. Since the discovery of T-cell growth factor (TCGF), systems are now available for the long-term specific in vitro propagation of mature normal or neoplastic human T cells, providing an opportunity to study the influence of T cells on hematopoiesis. Recently, 24 cell lines from patients with cutaneous T-cell lymphoma (CTCL) and T-cell acute lymphoblastic leukemia (T-ALL) were grown with TCGF and then assessed for release of humoral factors that affect hematopoiesis. Conditioned media (CM) from these cell lines were tested for erythroid burst-promoting activity (BPA) and granulocyte colony-stimulating activity (CSA). BPA was detected in CM from 3/6 cultures of T-ALL patients and 4/6 CTCL cultures. CSA was found in the CM from 6/8 cultures of T-ALL patients, 7/12 CTCL cultures, and 3/4 CTCL cell lines that become independent of exogenous TCGF for growth. The CSA from several of the neoplastic T-cell cultures stimulated high levels of eosinophil colonies, a possible source of the eosinophilia seen in these patients. The ability of continuously proliferating human T lymphocytes, which retain functional specificity and responsiveness to normal humoral regulation, to produce factors that directly or indirectly stimulate myeloid and erythroid colony formation lends further credence to the role of T lymphocytes in regulating hematopoiesis.

Cell Line↗
PubMed1981

Agglutination of Erwinia stewartii Strains with a Corn Agglutinin: Correlation with Extracellular Polysaccharide Production and Pathogenicity.

A bacterial agglutinin was extracted from ground corn (WI hybrid 64A x W117) seed with phosphate-buffered saline (pH 6.0) and precipitated with (NH(4))(2)SO(4) at 70% saturation. The activities of this agglutinin against 22 strains of Erwinia stewartii (agent of bacterial wilt of corn) that varied in virulence were determined. Specific agglutination (agglutination titer per milligram of protein per milliliter) values were correlated negatively with virulence ratings. Strains with high specific agglutination values (15 or higher) were avirulent or weakly virulent; strains with low specific agglutination values (10 or lower) were highly virulent, with two exceptions. Avirulent strains produced butyrous colonies and released only small amounts of extracellular polysaccharide (EPS) into the medium, and the cells lacked capsules; virulent strains produced fluidal colonies and released large amounts of EPS, and the cells were capsulated. There was a strong correlation between the amount of EPS produced by each strain (as determined by increase in viscosity of the medium) and the specific agglutination value; in contrast, lipopolysaccharide compositions were similar in all strains. When cells of six fluidal strains were washed by repeatedly centrifuging and resuspending them in buffer, they were agglutinated more strongly by corn agglutinin than were unwashed cells. When avirulent cells were washed, their specific agglutination values did not increase significantly. Eight EPS-deficient mutants of E. stewartii, selected for resistance to the capsule-dependent bacteriophage K9, had lower virulence but higher specific agglutination than did their corresponding wild-type parents. Production of EPS appears to be essential for virulence; EPS may prevent agglutination of bacteria in the host, thus allowing their multiplication.

Journal Article↗
PubMed1981

Cooperativity of concanavalin A patching and its influence on cytoskeleton changes in fibroblast rounding and detachment.

We have studied the extent of concanavalin A (Con A) patching on spread fibroblasts as a function of increasing concentration of added Con A, and also the influence of this patching on subsequent cytoskeleton changes during exposure to trypsin and EGTA. Living cells do not patch at low concentrations of Con A (around 1 microgram ml-1) but progressively do so at higher levels (2-10 microgram ml-1), in very close parallel with a cooperative phase of binding characterized earlier. The proportion of visibly patched cells is at a maximum when this cooperative phase is complete and the correlation remains when cells are treated with azide of cytochalasin B to shift the concentration range over which both phenomena occur. All this evidence points to a common origin for cooperative binding and visible patching which is sensitive to the state of cellular actomyosin, and involves the mediation of actin-associated structures. As a consequence of Con A patching, cell attachment is preserved against the action of EGTA. On patched cells, this agent causes minor if any changes in cell shape and in the distributions of microtubules and 10-nm filaments, but actin stress fibres are dispersed. However, conditions appear to be retained for reassembly of the stress fibres because these can be caused to reappear within minutes after removal of EGTA when glucose, or Ca2+ or Mn2+ in the absence of glucose, is supplied in the medium. Trypsin caused only partial destruction of stress fibres in Con A-treated cells and did not promote detachment or dispersal of microtubules or 10-nm filament systems.

Animals↗