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Biomedical subjects

S Denham

Publications and source records attributed to S Denham.

At least 19 recordsLinked to original sources
PubMed2000

Q-sort assessment of attachment security during the preschool years: links from home to school.

This study investigated relations among preschoolers' secure-base behavior with mother at home, stressful family conditions, and qualities of developing relationships with peers and teachers in preschool. Preschool-age children (N = 94; 51 boys and 43 girls) and their mothers were observed during multiple home visits, and their security of attachment was assessed with the Attachment Q-Set. Children in families with lower levels of stress had more secure attachment relationships with mothers. Both boys and girls who were less securely attached to their mothers expressed significantly more anger-aggression in preschool. For boys, higher levels of family stress were also significantly related to anger-aggression and to social competence in preschool. In addition, boys who were more securely attached to their mothers were more securely attached to their preschool teachers and were more popular with peers in preschool.

Child, Preschool↗
PubMed1999

Computational models of predictive and memory-related functions of the hippocampus.

We discuss the role of the hippocampus in information processing in the brain and hypothesise that the hippocampus monitors the stability of sensory cues it receives from the external world, using the current context to predict the next sensory event in the episodic sequence by learning from experience, and memorising these sequences of sensory events. Two computational models are presented here. The predictive theory and model are closely related to experimental evidence and use dynamic synapses with an asymmetric learning rule to develop predictive neural activity of a leaky integrate-and-fire model of a pyramidal CA3 cell. The oscillatory model of the hippocampus for memorising sequences of sensory events is developed as a chain of interacting neural oscillators forced by oscillatory inputs from the entorhinal cortex and from the medial septum.

Animals↗
PubMed1998

Overview of the Second International Workshop to define swine cluster of differentiation (CD) antigens.

The aim of the Second International Swine Cluster of Differentiation (CD) Workshop, supported by the Veterinary Immunology Committee (VIC) of the International Union of Immunological Societies (IUIS), was to standardize the assignment of monoclonal antibodies (mAb) reactive with porcine leukocyte differentiation antigens and to define new antibody clusters. At the summary meeting of the workshop in July, 1995, revisions in the existing nomenclature for Swine CD were approved, so that the rules are now in accord with those for human and ruminant CD. Swine CD numbers will now be given to clusters of mAb to swine orthologues of human CD molecules when homology is proven by (1) suitable tissue distribution and lymphoid cell subset expression, (2) appropriate molecular mass of the antigen recognized by the mAbs, and (3) reactivity of mAbs with the cloned swine gene products, or cross-reactivity of the mAb on the human gene products. In some cases, this reactivity would not be fully proven, mainly due to the lack of cloned gene products; for these CD antigens, the respective clusters will be assigned by the prefix 'w' which will lead to 'wCD' antigens. As a result of the Second International Swine CD Workshop the assignment of 16 mAb to existing CD groups (CD2a, CD4a, CD5a, wCD6, wCD8, CD14, CD18a, wCD21, wCD25) was confirmed, and 2 mAb to existing swine workshop clusters (SWC). More importantly, for the work on the porcine immune system, was the definition of 5 new swine CD antigens, namely CD3 (recognized by 6 new mAb and 3 epitopes), CD16 (1 new mAb), wCD29 (2 mAb), CD45RA (3 mAb) and CD45RC (1 new mAb). Finally, the demarcation of two new SWC molecules in swine, SWC8 (2 mAb) and SWC9 (2 mAb) was confirmed.

Animals↗
PubMed1998

Monoclonal antibodies putatively identifying porcine B cells.

Comparison was made of the binding of 38 test and three standard monoclonal antibodies (mAbs) to B cells from various pig lymphoid tissues by flow cytometry (FCM) and immunohistochemistry. Some mAbs were also tested on B cells from foetal pig tissues. Twenty of the new mAbs bound, though to variable degrees, to porcine B cells but only three were given cluster assignations: C35 (#147) and BB6-11C9 (#167) were assigned to wCD21 and 2F6/8 (#057) was assigned to SWC7.

Animals↗
PubMed1998

Expression of biologically active recombinant porcine GM-CSF by baculovirus gene expression system.

The full length porcine granulocyte/macrophage colony stimulating factor (GM-CSF) cDNA, including secretion signal peptide coding region was recloned into baculovirus transfer vector pAcYM1. The vector was then transfected with Autographica californica nuclear polyhedrosis virus (AcNPV) DNA into SF21AE cells and the recombinant virus AcPGM was recovered. Recombinant porcine GM-CSF (rpGM-CSF) was obtained from the serum-free culture medium of Tn5 cells infected with the AcPGM virus, and was shown to be a glycosylated 21 kDa protein as confirmed by tunicamycin treatment and [3H]-glucosamine uptake. The biological activities of rpGM-CSF in AcPGM-infected cell culture supernatants were demonstrated by porcine bone marrow cell proliferation and haematopoietic cell colony formation assays. The use of rpGM-CSF enabled us to culture porcine monocytes/macrophage and dendritic-like cells, derived from either porcine bone marrow or peripheral blood, for up to 4 months.

Amino Acid Sequence↗
PubMed1996

Granulocyte-macrophage colony stimulating factor promotes prolonged survival and the support of virulent infection by African swine fever virus of macrophages generated from porcine bone marrow and blood.

Long-surviving cultures of non-adherent cells of the monocyte-macrophage lineage were established from the bone marrow and blood of weanling pigs by culturing cells from these tissues in the presence of recombinant porcine granulocyte-macrophage colony stimulating factor (GM-CSF). The cells increased in number, principally during the first 4 weeks of culture, bound monoclonal antibodies recognizing porcine macrophage antigens and avidly phagocytosed latex particles. The GM-CSF generated mononuclear phagocytes were highly infectible [correction of infectable] with a virulent Malawi isolate of African swine fever virus (ASFV) and able to generate levels of virus progeny similar to those produced by freshly isolated pig macrophages. The cultured cells retained their susceptibility to ASFV infection for as long as the cultures survived i.e. for up to 3 months.

African Swine Fever Virus↗
PubMed1995

G-CSF is a major component of colony-stimulating activity (CSA) in the plasma of patients with multiple myeloma after treatment with high-dose melphalan (HDM).

Colony-stimulating activity (CSA) was measured by the production of granulocyte-macrophage colony-forming units (GM-CFU) from normal donor bone marrow in the plasma of 29 patients with multiple myeloma (MM) after intensive treatment with high-dose melphalan (HDM) with or without autologous bone marrow rescue (ABMR). Although patients who received ABMR had an earlier recovery of circulating neutrophils compared with those who received HDM alone, the time at which CSA reached a maximum was similar in both groups (10 to 11 days) after therapy. The decline in CSA correlated with the recovery of the neutrophil count. In plasma from patients who received recombinant human granulocyte colony-stimulating factor (rhG-CSF), in addition to an autograft, CSA reached a maximum earlier (7 days). Furthermore, neutrophil recovery was earlier in these patients. Platelet recovery was not increased by rhG-CSF. The time at which CSA was maximum in four patients who were undergoing intensive therapy for the second time occurred 9 days after treatment with HDM. Although the period without neutrophils was longer in three (of four) patients who survived long term, one patient who received rhG-CSF had a shorter period of neutropenia than the two who had not had the cytokine. G-CSF was detected in plasma from seven of seven patients but not at all times after treatment. In plasma samples that contained G-CSF, colony numbers were increased by recombinant interleukin-4 (rIL-4) in vitro. Neither IL-3 nor GM-CSF was detected in plasma; however, antibody to GM-CSF reduced CSA in all samples after intensive therapy. The data suggest that CSA is a consistent physiologic response to intensive therapy, even in previously treated patients, but that hematologic recovery is dependent on the availability of viable progenitor cells.

Bone Marrow Transplantation↗
PubMed1994

Monoclonal antibodies recognising differentiation antigens on porcine B cells.

Nineteen monoclonal antibodies (mAbs) submitted to the porcine CD Workshop were analysed on porcine B cells from different lymphoid tissues by flow cytometry and immunohistochemistry. Six mAbs only bound to pig B cells and three of these were assigned cluster numbers, 76-7-4 (No. 001):CD1, K231-3B2 (No. 027):CD25 and CC51 (No. 100):CD21. Of the three remaining B cell positive mAbs, one was assigned to a swine cluster, CC55 (No. 101):SWC7, a second, LIG4 (No. 123), recognised cell surface IgM and the third, MUC106A (No. 072), remained unassigned.

Animals↗
PubMed1993

The stimulation by dendritic cells of host-versus-graft reactivity in vivo.

Dendritic cells (DC) isolated from peripheral intestinal lymph of inbred Wistar rats were injected into the hind footpads of Hooded CBH/Cbi rats. Administration of 10(4) and 5 x 10(5) allogeneic DC produced approximately six-fold increase in popliteal node weight. This is only marginally greater than that caused by similar doses of syngeneic DC and about 30% greater than that caused by allogeneic mononuclear cells. The data indicated that allogeneic DC were not effective stimulators of host-versus-graft reactions in this assay.

Animals↗
PubMed1992

Recombinant mouse monoclonal antibodies with single amino acid substitutions affecting Clq and high affinity Fc receptor binding have identical serum half-lives in the BALB/c mouse.

The serum half-lives of three recombinant mouse monoclonal antibodies, differing radically in their ability to bind to Clq or FcRI but only minimally in structure, were determined in the BALB/c mouse following intravenous administration. The wild-type antibody, a chimaeric antibody comprising variable domains binding 3-iodo-4-hydroxy-5-nitrophenylacetate and constant domains of the mouse IgG2b isotype, was eliminated from the bloodstream with biphasic kinetics: alpha-phase, 0.5 days; beta-phase, 7.0 days. The alpha- and beta-phase half-lives of mutant recombinant antibodies with single amino acid substitutions, either Glu 235-Leu allowing binding to the mouse FcRI, or Lys 322-Ala reducing Clq binding 30-fold, were indistinguishable from those of the wild-type antibody demonstrating that the biological half-life of intact mouse IgG is independent of the ability to bind Clq or FcRI. The major implication of the present study is that IgG molecules which have been genetically engineered to eliminate interaction with other components of the immune system should retain the long half-life typical of natural antibodies.

Animals↗
PubMed1992

Inhibition of the reactive proliferation of lymphocytes by activated macrophages: the role of nitric oxide.

The effects of nitric oxide synthesis by activated macrophages on concanavalin A (Con A) stimulated lymphocyte proliferation and the modulation of these events by extraneous L-arginine concentration were investigated. In 1 mM or 5 mM exogenous L-arginine, inhibition of proliferation of a fixed number of lymphocytes was progressively inhibited in the presence of increasing numbers of macrophages. This inhibition was related to increased nitric oxide synthesis by the macrophages and was suppressed in the presence of NG-monomethyl-L-arginine (NMMA), a specific inhibitor of nitric oxide synthesis. Inhibition of nitric oxide synthesis by 500 microM NMMA was less effective at high concentrations of macrophages, and in 5 mM as compared with 1 mM L-arginine. In the absence of exogenous L-arginine, NMMA inhibited lymphocyte proliferation in the presence of low numbers of macrophages but appeared to promote proliferation at high macrophage concentrations. Membrane separation of lymphocytes and macrophages led to loss of the nitric oxide mediated inhibitory effect on lymphocyte division except at the highest concentrations of macrophages used. Inhibition of lymphocyte proliferation could not be associated with L-arginine depletion of the media by macrophages or by the action of nitrite ions, a product of nitric oxide oxidation.

Arginine↗
PubMed1990

The rat FcR for monomeric IgG is preferentially expressed on red pulp macrophages in the spleen.

Rat monoclonal IgG2b immunoglobulins labelled with 125I or biotin were localized in the red pulp areas but were not found in the marginal zones of the white pulp of the spleen 8 hr after their i.v. injection. In cell suspensions made from the spleen, 90% of red pulp macrophages (M phi) bound 125I-IgG2b monomeric proteins in vitro, whereas similar estimates for marginal zone M phi were 12-30%. Red pulp and marginal zone M phi were distinguished primarily by monoclonal antibodies (mAb) ED2 and ED3, but also by their ability to take up FITC-labelled Ficoll in vivo.

Animals↗
PubMed1989

Some properties of dendritic macrophages from peripheral lymph.

Peripheral lymph was collected from the skin and liver of sheep, and from the intestine of rats. The dendritic macrophages contained in it were isolated by centrifuging the lymph over a layer of 'Nycodenz'. Similar cells were produced by culturing mononuclear cells from venous blood, but the yields were very small. The numbers of dendritic cells in the lymph from the legs of sheep increased five-fold after xylene had been applied to the skin. Dendritic macrophages displayed abundant class II histocompatibility antigens on their surfaces, as well as immunoglobulins. Although the latter were probably acquired passively, they remained present for several days on cells cultured in vitro. When in vitro, dendritic cells could be shown to phagocytose marker particles, such as latex beads, but their performance was unimpressive compared to macrophages from the peritoneal cavities of rats. In contrast, their ability to phagocytose rapidly T4 phage or influenza viruses unequivocal and striking.

Animals↗
PubMed1988

Studies on the adjuvant action of beryllium. III. The activity in the plasma of lymph efferent from nodes stimulated with beryllium.

Efferent lymph from the popliteal or prefemoral lymph nodes was collected from unanaesthetized sheep before and after the injection of insoluble Be(OH)2 into the subcuticulum that was drained by the nodes. Sterile, cell-free plasma from lymph collected during the 48 hr after the injections, induced vigorous lympho-proliferative responses in naive lymph nodes after s.c. injection into autochthonous or allogeneic recipients. The same lymph had an adjuvant action when injected i.p. into both nude and euthymic rats. Many samples of such lymph were screened for biological activity in rats by noting the increase in the weight of the regional popliteal nodes that occurred after the test sample had been injected into the footpad. All the active samples were shown, by atomic absorbance spectroscopy, to contain beryllium, and we concluded that this metal, in the form of soluble Be-protein adducts, was probably the prime mover in all the observed responses.

Adjuvants, Immunologic↗