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N Matthews

Publications and source records attributed to N Matthews.

At least 37 records · Page 2Linked to original sources
PubMed1996

Active systemic lupus erythematosus is associated with the recruitment of naive/resting T cells.

The aim of this study was to determine whether active systemic lupus erythematosus (SLE) is associated with recruitment of resting CD45RA+ T cells or reactivation of CD45RO+ memory T cells. Three-colour immunofluorescence was used to determine CD45 isoform expression by CD4+ T cells from 28 patients with SLE. Newly recruited and highly differentiated primed T cells were distinguished by their CD45RB expression. The pattern of CD45 isoform expression varied directly with time since the onset of symptoms in patients with active SLE. Shortly after symptoms appeared, most cells were CD45RA+ resting cells or CD45RO(dull)RB(bright) early primed cells. However, over the course of active disease, patients accumulated CD45RO(bright)RB(dull) cells which represent an advanced state of differentiation. The switch from an early to late primed phenotype correlated significantly with time since the onset of symptoms. The recruitment of resting T cells in active SLE, rather than the simple reactivation of existing memory clones, has implications for understanding the pathology of this disease and for treating it.

Biomarkers↗
PubMed1995

Structure-activity relationships of phenothiazines in inhibiting lymphocyte motility as determined by a novel flow cytometric assay.

Lymphocyte motility is highly dependent on rapid changes in cell shape. The human T-lymphoma cell line, MOLT-4, is constitutively shape-changing and motile, and both of these properties can be inhibited by the phenothiazine, chlorpromazine, as assessed by video analysis and migration across polycarbonate filters. In this paper, the light-scattering facility of a flow cytometer has been used to establish a simpler and more quantitative means of measuring changes in shape. By this method, the structure activity relationship (SAR) of phenothiazines and related compounds has been determined. The most active compounds had the tricyclic phenothiazine nucleus with a constrained dialkylaminoalkyl substituent at the nitrogen. The SAR for inhibition of lymphocyte motility differs from those reported for neuroleptic effects and for inhibition of PKC or calmodulin. Phenothiazine concentrations that inhibited lymphocyte shape-changing resulted in reduced F-actin concentrations. This indicates that the probable mode of action is disruption of mechanisms regulating actin polymerisation.

Actins↗
PubMed1995

Inhibition of protein kinase C results in a switch from a non-motile to a motile phenotype in diverse human lymphocyte populations.

Circulating lymphocytes are rounded, non-motile cells which on contact with cytokines, specialized or activated endothelium, acquire a constantly shape-changing, polarized morphology which enables migration into appropriate sites. The biochemical mechanisms which regulate this switch are not understood but the various stimuli may have a common final pathway. In this study we show that protein kinase C (PKC) inhibitors of the bisindolylmaleimide type (GF 109203X, Ro 31-8220, CGP 41,251) induce resting, spherical lymphocytes to change rapidly (< 30 min) into polarized, locomotory cells. This phenomenon was seen with diverse populations of blood T lymphocytes, tonsillar B cells and Jurkat and Molt4 T-cell lines. Consistent with this, down-regulation of PKC by chronic treatment (44 hr) with bryostatin also induced the polarized phenotype in blood lymphocytes and non-motile Molt4 cells. Conversely, treatment of a spontaneously motile subline of Molt4 cells with various PKC activators caused a reversion to the non-motile phenotype within minutes. PKC activation must be sufficient to overcome the effects of a constitutively active phosphatase because bisindolylmaleimide induction of motility could be prevented by pretreatment of the cells with a phosphatase inhibitor, calyculin A. It is concluded that, in resting lymphocytes, chronic activation of a PKC offsets the action of a constitutively active phosphatase and the net result is maintenance of the non-motile state. Agents which alter the kinase/phosphatase balance in favour of dephosphorylation result in induction of the locomotory phenotype.

Alkaloids↗
PubMed1994

Effect of serine/threonine kinase inhibitors on motility of human lymphocytes and U937 cells.

Mononuclear cell migration across the endothelium and through connective tissue into inflammatory sites is a multi-step process. After adhesion to the endothelium, there is an initial change in shape from spherical to irregular, followed by the migratory phase itself in which the cells constantly change in shape. In this paper we have investigated the possibility that the shape-changing in this latter phase is controlled by serine/threonine phosphorylation. For this purpose, we used a spontaneously shape-changing variant of U937 monocytoid cells as well as human peripheral blood lymphocytes that had been previously activated by anti-CD3. To test the role of phosphorylation in shape-changing, a wide range of serine/threonine kinase inhibitors was tested, including ML-7, KT5720, KT823, H7, H8, staurosporine, calphostin C, sphingosine, bisindolylmaleimide, chelerythrine and KN-62. Only those compounds which inhibited protein kinase C prevented lymphocyte and U937 shape-change and transmigration across polycarbonate filters. However, one specific protein kinase C inhibitor, bisindolylmaleimide, stimulated lymphocyte shape-change. In conclusion, these studies show that activation of a serine/threonine kinase is necessary for the constant shape-changing required for motility of mononuclear cells. The kinase may be a protein kinase C isotype or a closely related enzyme.

Alkaloids↗
PubMed1993

Nitric oxide is produced during TNF killing of U937A cells but does not contribute to the cytotoxic process.

Proinflammatory cytokines, including TNF, stimulate nitric-oxide free radical production in a variety of tissues through the induction of the enzyme nitric-oxide synthase. As free radicals are considered likely candidates in the cytotoxic action of TNF, we examined nitric oxide production in TNF-sensitive U937A and TNF-resistant U937A/R cells and its potential role in TNF-induced cytotoxicity. TNF stimulated U937A nitrite production through a process that was abolished by the competitive inhibitors of nitric-oxide synthase N-omega-nitro-L-arginine methyl ester (NAME) and N-G-monomethyl-L-arginine (NMMA) without inhibition of TNF-induced cytotoxicity. TNF also increased nitrite production in TNF-resistant U937A/R cells. In addition, the cytotoxic action of TNF was independent of L-arginine substrate availability. Thus, although cytokine-inducible nitric oxide production is emerging as an effective antitumour mechanism, here, TNF clearly exerted potent antitumour activity against U937A cells through a nitric-oxide-independent mechanism.

Animals↗
PubMed1993

Subpopulations of primed T helper cells in rheumatoid arthritis.

OBJECTIVE: To analyze subsets of primed T helper cells, defined by expression of the CD45RB isoform of the leukocyte common antigen, in the blood and synovial fluid (SF) of patients with rheumatoid arthritis (RA). METHODS: Three-color immunofluorescence was used to study CD45 isoform expression by peripheral blood and SF CD4+ T cells. RESULTS: CD45 isoform expression in the peripheral blood of patients with either RA or reactive arthritis did not differ from that in healthy controls. SF T cells from both RA patients and reactive arthritis patients were almost exclusively primed (CD45RO+) cells. RA SF T cells expressed very low levels of CD45RB; this is the most highly differentiated subset of primed cells. Patients with acute reactive arthritis showed higher levels of CD45RBbright cells in their synovial fluid. CONCLUSION: The highly selected cell population in SF, representing one subset of primed cells, may relate to the apparent functional abnormalities of cells from this site in patients with RA.

Adult↗
PubMed1993

Synthesis of the foetal protein fetuin by early developing neurons in the immature neocortex.

The presence of the foetal protein fetuin has previously been demonstrated by immunocytochemistry to be specifically confined to the primordial plexiform layer, the early cortical plate and subplate zone cells in the developing neocortex of a number of species. In order to investigate its origin there, we have applied in situ hybridization in paraffin sections of Bouin's fixed foetal sheep brain, using a short anti-sense oligonucleotide probe. The distribution of fetuin mRNA has been compared with that of the protein by using anti-fetuin antibodies and immunocytochemistry. This allowed us to confirm that fetuin is synthesised initially in cells of the primordial plexiform layer and subsequently cortical plate and subplate cells. On the other hand, cells in the ventricular zone that are fetuin (protein) positive do not contain detectable fetuin mRNA. The time course of fetuin mRNA expression in the developing neocortex follows closely the previously described pattern of fetuin (protein) distribution in the sheep brain, apart from its absence from the ventricular zone where its origin is probably by uptake from cerebrospinal fluid.

Animals↗
PubMed1993

Zn-binding globulin in human fetal brain and liver: a marker for passive blood/CSF transfer of protein.

The presence of Zn-binding globulin (ZnbG) during human fetal development was studied in cerebrospinal fluid (CSF) and plasma with immunodiffusion methods and in brain, CSF, plasma and liver using immunocytochemical methods. At the earliest stages examined with immunocytochemistry (5-6 weeks gestation) no staining for ZnbG was visible in liver, plasma, CSF or brain. However, the primitive mesenchyme exhibited a prominent staining reaction. In late embryonic and early fetal stages, staining for the protein was most prominent in the spinal cord, brain stem and diencephalon and in the choroid plexuses and marginal and subplate zones in the telencephalon. At the cellular level, synaptic strata and territories were most strongly stained. The distribution of ZnbG in the early developing central nervous system suggests that this protein may be involved in the initial establishment of CNS circuitry. Embryonic brain was positive for ZnbG well before the protein could be detected in CSF, plasma or liver. The early occurrence of ZnbG in brain tissue prior to its presence in liver or plasma also suggests that the protein is synthesized in early fetal brain. At the time when CSF first became positive (17 weeks gestation), the brain staining had largely disappeared. ZnbG in plasma increased throughout gestation to reach 2.6 +/- 0.4 mg/100 ml at term and subsequently increased to an adult value of 6.8 +/- 1.5 mg/100 ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Reduced levels of alpha-1-antitrypsin in children exposed to high levels of air pollution.

Health risks associated with environmental pollution, particularly in Eastern Europe, are a cause for concern. In order to gain some insight into the effects of exposure to high levels of air pollution particularly by heavy metals, we measured the concentration of nine plasma proteins in plasma samples from newborn babies and 5- to 6-year old children living in heavily polluted areas of Poland, as well as from some newborns and adults from unpolluted areas of Poland and control samples within the local Southampton population. The concentrations of all proteins measured were in or close to their expected range, with the exception of alpha 1-antitrypsin (alpha 1AT). The concentration of this protein was lower in both groups of Polish children from the polluted areas, particularly in the 5- to 6-year old group. These children were shown to be phenotypically normal. Since adult levels of alpha 1AT are usually reached within 2 weeks postpartum, these findings raise the possibility that continued exposure to high levels of pollution may lead to reduced levels of alpha 1AT in plasma; this may compound the impairment of lung function in children living in highly polluted areas.

Air Pollutants↗
PubMed1993

Studies of lymphocyte transendothelial migration: analysis of migrated cell phenotypes with regard to CD31 (PECAM-1), CD45RA and CD45RO.

CD31 is a 130,000 MW cell-surface glycoprotein expressed on endothelial cells, polymorphonuclear leucocytes, monocytes and about 50% of peripheral blood lymphocytes, and it has been proposed that it plays a role in transendothelial migration. If it is involved in endothelial transmigration of lymphocytes then the proportion of CD31+ cells should be increased in the lymphocyte population which has crossed an endothelial monolayer. This was tested using two endothelial types, namely human umbilical vein endothelial cells (HUVEC) and rat high endothelial venule (RHEV) cells. As a control, lymphocyte CD45RA and CD45RO expression was also determined since there is a correlation between lymphocytes bearing these isoforms and different migratory patterns. Double labelling techniques showed a close correlation between CD31 and CD45RA expression. With HUVEC monolayers, the transmigrated lymphocyte population was depleted of CD31+ cells. This depletion was even more marked if the HUVEC monolayers had been stimulated with interleukin-1 beta (IL-1 beta). The migrated lymphocytes were enriched for CD31-CD45RO+ cells but depleted of CD31+CD45RA+ cells. In addition, lymphocyte populations depleted of CD31+ cells by immunopanning were also able to migrate across HUVEC monolayers. Taken together these data suggest that lymphocyte CD31 expression is not necessary for transmigration across HUVEC monolayers and, if anything, is negatively correlated with transmigration. With the second endothelial cell type, RHEV cells, there was no consistent change in the proportion of CD31+ lymphocyte in the transmigrated population, suggesting neither a positive nor a negative correlation between CD31+ expression and lymphocyte transmigration across RHEV cells. However, with both endothelial cell types, the migrated lymphocyte populations were enriched for the marker CD45RO. In conclusion, lymphocyte surface expression of CD31 is not necessary for transmigration across the endothelial cell types used in this study, but with both cell types an enrichment of CD45RO+ lymphocytes is seen in the migrated population.

Antigens, Differentiation, Myelomonocytic↗
PubMed1992

Fetuin: an acute phase protein in cattle.

Fetuin is a plasma protein present in high concentrations during fetal development in animals of the order Artiodactyla. Its role is not known. The human homologue of fetuin--alpha 2HS glycoprotein--has been shown to be a negative acute phase protein in adult plasma. In the present study, the concentration of fetuin was measured in the serum of healthy cattle (Bovis bovis) and in animals with various injuries and inflammatory disorders. The levels were decreased by 30% in pregnancy but increased up to 10-fold in some trauma cases. A significant negative correlation between the concentrations of fetuin and albumin has also been found. Thus, fetuin appears to be a positive acute phase protein in cattle.

Acute-Phase Proteins↗
PubMed1992

Tumour necrosis factor induction of ELAM-1 and ICAM-1 on human umbilical vein endothelial cells--analysis of tumour necrosis factor-receptor interactions.

Induction of the adhesion molecules ELAM-1 and ICAM-1 on endothelial cells is a key pro-inflammatory effect of tumour necrosis factor (TNF). Earlier work in non-human systems has suggested that unlike other cell types, endothelial cells interact with the N-terminus of the TNF molecule, thereby implying novel TNF receptors on endothelial cells. This is also supported by 125I-TNF cross-linking studies on bovine endothelial cells. The present study aimed to see whether TNF induction of ELAM-1 and ICAM-1 on human umbilical vein endothelial cells (HUVECs) involved novel TNF-receptor interactions. Three approaches were employed. First, antibodies directed at different sites on the TNF molecule were tested for inhibition of TNF-induction of ELAM-1 and ICAM-1 on HUVECs. Inhibition was seen only with antibodies reacting with epitopes outside the N-terminal region. Second, an N-terminal TNF peptide (residues 1-26) failed to induce ELAM-1 and ICAM-1 on HUVECs or antagonise TNF induction of these molecules. Third, HUVEC/125I-TNF cross-linking revealed a major complex characteristic of the known 55 kDa TNF receptor: this was confirmed with receptor-specific monoclonal antibodies. It is concluded that (a) the same part of the TNF molecule interacts with TNF-receptors on HUVECs and other cell types and (b) TNF induction of ELAM-1 and ICAM-1 on HUVECs is mediated via the well-characterized 55 kDa TNF receptor.

Cell Adhesion Molecules↗
PubMed1992

Autoimmunity to collagen in adult periodontal disease: immunoglobulin classes in sera and tissue.

The immunoglobulin class distribution of antibody to human collagen type I has been examined in sera and gingival extracts from patients with adult chronic periodontitis. Tissue extracts were made either by simple washing or ultrasonication. With either method, IgG and IgA antibodies to collagen were present in higher concentration in tissue extracts than in autologous serum when adjustment was made for dilution differences. No significant differences were found for IgM antibodies. Antibodies to human collagen type I are usually "natural antibodies" of the IgM class and, therefore, our findings suggest a class switch to IgG in inflamed gingivae, presumably due to prolonged antigenic stimulation.

Adult↗
PubMed1991

Inducibility of class II major histocompatibility complex antigens by interferon gamma is associated with reduced tumorigenicity in C3H mouse fibroblasts transformed by v-Ki-ras.

Paired lines of C3H mouse fibroblasts transformed with murine sarcoma virus (Kirsten strain) were prepared that express high or low levels of class II major histocompatibility complex antigen after treatment with interferon gamma (IFN-gamma). Here, we described a comparison of the tumorigenicity of these lines in euthymic syngeneic and thymus-deficient nu/nu mice and in mice depleted of IFN-gamma. The class II-inducible cells are clearly less tumorigenic than the noninducible cells in syngeneic mice, but of similar tumorigenicity in nu/nu mice and in mice treated with antibodies to deplete IFN-gamma. We propose that in this system, IFN-gamma induction of class II antigens on the tumor cell surface operates to limit tumor growth; ras expression, which inhibits induction of class II antigens, prevents this and so allows tumor growth.

Animals↗
PubMed1991

Triiodothyronine in the recovery of stunned myocardium in dogs.

Two groups of dogs were subjected to a 15-minute period of regional myocardial ischemia by snaring the left anterior descending coronary artery proximal to its first diagonal branch. After release of the snare, the dogs were given either placebo (group 1: n = 7) or triiodothyronine (T3) therapy (group 2: n = 6). The dose of T3 given was 0.2 microgram/kg at 30-minute intervals to a total of six doses. Plasma free T3 level fell significantly during the ischemic period in both groups and continued to fall after reperfusion in group 1. In both groups, cardiac function deteriorated significantly during the period of ischemia and rapidly returned to control level after reperfusion. After 90 minutes of reperfusion, however, deterioration of left ventricular function was observed in group 1 and was significantly worse than in group 2, in which hemodynamic function was maintained and, in fact, improved to levels superior to control. It is suggested that T3 therapy may be worthy of trial in patients in whom reperfusion of the myocardium takes place after a relatively short ischemic period (the "stunned myocardium").

Animals↗
PubMed1991

Development of tumor cell resistance to tumor necrosis factor cytolysis results in reduced fibronectin binding and altered ganglioside expression.

U937A cells are highly susceptible to tumor necrosis factor (TNF) cytolysis. They are also motile and incorporate fibronectin into the extracellular matrix (ECM). This takes the form of a dense fibrillar network in confluent cultures, but in sparse cultures appears as a "snail trail" of insolubilized fibronectin behind the moving cell. In contrast, U937A/R cells selected for resistance to TNF cytolysis are poorly motile and, although they synthesize fibronectin, fail to incorporate it into the ECM. Compared to U937A/R, U937A cells spread more rapidly and extensively on fibronectin-coated plastic and also bound 125I-fibronectin more effectively. Inhibition of U937A spreading on fibronectin required higher doses of GRGDSPK peptide, indicating greater expression on U937A of integrin-type, fibronectin receptors. Gangliosides are non-integrin structures which can bind fibronectin, and there were also qualitative and quantitative differences in ganglioside expression with U937A having two to five times more than U937A/R. Therefore the development of TNF resistance by U937A/R cells is accompanied by a reduced ability to interact with fibronectin, and this probably accounts for the reduced motility and inability to deposit fibronectin in the ECM.

Amino Acid Sequence↗
PubMed1991

Human neutrophil responses to pathogenic Escherichia coli are receptor-specific and selectively augmented by recombinant human tumor necrosis factor-alpha.

The effect of recombinant human tumor necrosis factor-alpha (rhTNF alpha) on neutrophil (PMNL) response to uropathogenic Escherichia coli was assessed. A strain expressing mannose-sensitive adhesins (type 1 fimbriae) stimulated significant primary granule, secondary granule, and leukotriene B4 (LTB4) release. The same strain grown to suppress fimbrial expression and three non-type 1-fimbriated strains stimulated only background low-level PMNL activation. The binding of the type 1-fimbriated strain to PMNL was inhibitable by D-mannose and concanavalin A, while that of non-type 1-fimbriated strains was not but was inhibited by antibodies to the PMNL complement receptors 1 and 3. TNF alpha (10(-9) M) synergistically augmented the non-type 1-fimbriated E. coli-stimulated LTB4 release and additively increased secondary granule release without affecting primary granule release. In contrast, none of the responses to the type 1-fimbriated strain were augmented by TNF alpha. In the absence of mannose-sensitive adhesins, the activation of PMNL by E. coli may involve both complement receptors 1 and 3 and be augmented by TNF alpha.

Bacterial Adhesion↗