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Biomedical subjects

J B Matthews

Publications and source records attributed to J B Matthews.

At least 73 records · Page 4Linked to original sources
PubMed2000

Evaluation of the response of primary human peripheral blood mononuclear phagocytes to challenge with in vitro generated clinically relevant UHMWPE particles of known size and dose.

The response of primary human peripheral blood mononuclear phagocytes to challenge with clinically relevant ultra-high molecular weight polyethylene (UHMWPE) wear debris of known particle size and dose was evaluated. Particles with a mean size of 0.24, 0. 45, 1.7, 7.6, and 88 microm were cocultured with cells for 24 h before assessment of cell viability and production of the osteolytic cytokines interleukin (IL)-1 beta, IL-6, tumor necrosis factor-alpha, and granulocyte macrophage colony-stimulating factor, and prostaglandin E(2). All particle fractions were evaluated at particle volume (microm(3)) to cell number ratios of 10:1 and 100:1, which had been previously identified as being the most stimulatory and clinically relevant. None of the test fractions had an effect on cell viability. Whereas the heterogeneity of human individuals was clearly evident in the responses of the donors evaluated in this study (the response of donor 3 was between 5 and 20 times greater than the other donors), the most biologically active particles were found to be submicrometer in size. Stimulation with phagocytosable particles (0.24, 0.45, and 1.7 microm) resulted in enhanced levels of cytokine secretion. Macrophages stimulated with particles outside this size range produced considerably less cytokines at the volumes tested. These results confirm earlier findings and suggest that the size and volume of UHMWPE particles are critical factors in macrophage activation. Furthermore, they suggest that the heterogeneity of human individuals may be another important factor in determining implant life.

Biocompatible Materials↗
PubMed2000

Comparison of the response of primary human peripheral blood mononuclear phagocytes from different donors to challenge with model polyethylene particles of known size and dose.

The response of primary human peripheral blood mononuclear phagocytes to challenge with polyethylene particles of known size and dose was evaluated. Particles with mean sizes of 0.21, 0.49, 4.3, 7.2, and 88 microm were co-cultured with cells for 24 h prior to the assessment of cell viability and production of the osteolytic mediators IL-1beta, IL-6, TNFalpha, GM-CSF and PGE2. All particle fractions were evaluated at particle volume (microm3) to cell number ratios of 10:1 and 100:1 which were previously identified as being the most biologically active and clinically relevant. The heterogeneity of human individuals was clearly evident both in the profile and the magnitude of the response of the donors evaluated in this study (the response of donor 5 being 2- to 15-fold lower than that of the other donors). Only the sub-micrometre particles stimulated significantly enhanced cytokine secretion at the ratios tested: mean particle sizes of 0.49 and 0.21 microm being the most biologically active. Macrophages stimulated with particles outside this size range produced considerably lower levels of mediator. These results compared favourably with the results of earlier studies, which demonstrated that particles within the phagocytosable size range (0.1-10 microm) were the most biologically active. These results, therefore, confirm earlier findings and suggest that the size and volume of polyethylene particles are critical factors in macrophage activation. Furthermore, they suggest that the heterogeneity of human individuals may be another important factor in determining implant life and could provide the basis for a valuable diagnostic tool to identify those patients most at risk of implant loosening.

Blood Donors↗
PubMed2000

Phylogenetic analysis of partial mitochondrial cytochrome oxidase c subunit I and large ribosomal RNA sequences and nuclear internal transcribed spacer I sequences from species of Cyathostominae and Strongylinae (Nematoda, Order Strongylida), parasites of the horse.

Three nucleotide data sets, one nuclear (ITS-2) and two mitochondrial (COI and l-rRNA), have been investigated in order to determine relationships among species of Strongylinae and Cyathostominae, intestinal parasites of the horse. The data exhibited a strong mutational bias towards A and T and in the COI gene, silent sites appeared to saturate rapidly partly due to this substitution bias. Thus, the COI gene was found to be less phylogenetically informative than the l-rRNA and ITS-2 genes. Combined analysis of the l-rRNA and ITS-2 genes supported a monophyletic clade of the cyathostomes with Tridentoinfundibulum gobi, which had previously been classified as a nematode of' uncertain origin'. The Strongylinae grouped consistently outside the clade containing the cyathostomes and T. gobi. Molecular analysis failed to provide strong evidence for the separation of cyathostomes into classical genera, as previously defined by morphological classification.

Animals↗
PubMed2000

Transforming growth factor-beta isoform expression in mature human healthy and carious molar teeth.

Transforming growth factor (TGF)-beta isoforms have been implicated in cellular signalling during tooth development and repair, but little is known of their cellular localisation or distribution within the dental tissues in the mature tooth. This study investigated the presence of TGF-beta1, beta2 and beta3 isoforms in tissues of sound and carious human molar teeth, to understand better the expression of TGF-betas during health and disease. In healthy tissues, odontoblasts, cells of the cell rich layer, pulpal fibroblasts and endothelial cells were stained to varying degrees for all isoforms, with TGF-beta3 showing the greatest intensity and TGF-beta1 the weakest intensity. Similar patterns of staining were observed in carious teeth; however, TGF-beta1 showed significantly increased staining intensity within odontoblasts and pulpal cells of carious teeth (p < 0.001). Biochemical analysis showed greater amounts of TGF-beta1 in tertiary dentine than in primary dentine samples. The expression of TGF-betas in odontoblasts and the increased presence of TGF-beta1 in tertiary dentine suggest that these isoforms may be important in odontoblast behaviour and the modulation of the tissue response to injury.

Edetic Acid↗
PubMed2000

Neurotensin stimulates Cl(-) secretion in human colonic mucosa In vitro: role of adenosine.

BACKGROUND & AIMS: Previous studies indicated that the peptide neurotensin (NT) stimulates Cl(-) secretion in animal small intestinal mucosa in vitro. In this study, we investigated whether NT causes Cl(-) secretion in human colonic mucosa and examined the mechanism of this response. METHODS: Human mucosal preparations mounted in Ussing chambers were exposed to NT. Drugs for pharmacologic characterization of NT-induced responses were applied 30 minutes before NT. RESULTS: Serosal, but not luminal, administration of NT (10(-8) to 10(-6) mol/L) induced a rapid, monophasic, concentration- and chloride-dependent, bumetanide-sensitive short-circuit current (Isc) increase that was inhibited by the specific nonpeptide NT receptor antagonists SR 48692 and SR 142948A, the neuronal blocker tetrodotoxin, and the prostaglandin synthesis inhibitor indomethacin. The mast cell stabilizer lodoxamide and the histamine 1 and 2 receptor antagonists pyrilamine and ranitidine, respectively, did not significantly alter NT-induced Isc increase. In contrast, the adenosine receptor 1 and 2 antagonists inhibited this secretory response, whereas the adenosine uptake inhibitors S-(4-nitrobenzyl)-6-thioguanosine and S-(4-nitrobenzyl)-6-thioinosine and the adenosine deaminase inhibitor deoxycoformycin potentiated NT-induced Isc increase. Serosal adenosine induced a rapid, monophasic, concentration- and chloride-dependent, bumetanide-sensitive Isc increase. CONCLUSIONS: NT stimulates chloride secretion in human colon by a pathway(s) involving mucosal nerves, adenosine, and prostaglandins.

Adamantane↗
PubMed2000

Mast cells, extracellular matrix components, TGFbeta isoforms and TGFbeta receptor expression in labial salivary glands in systemic sclerosis.

OBJECTIVE: To determine whether there was altered elaboration of non-collagenous extracellular matrix proteins or expression of TGFbeta isoforms and their receptors in salivary glands of patients with systemic sclerosis (SSc) and Raynaud's phenomenon (RP). Because of the possible role of mast cells in the early stages of SSc their presence was also investigated. METHODS: Sections of normal labial salivary glands (n=10) and glands from patients with SSc (n = 13) and RP (n = 5) were stained immunohistochemically and using acid toluidine blue. RESULTS: SSc glands contained more mast cells than control tissues (p<0.005) and similar numbers to those found in RP specimens. There were no differences in the pattern or amount of non-collagenous matrix proteins detected. Tenascin and elastin were predominantly found surrounding ducts whereas fibronectin had a more general distribution. TGFbeta isoforms and receptors were expressed by glandular epithelium, fibroblasts, vascular endothelium and inflammatory cells. Cell counts showed no differences in expression of TGFbeta1 or TGFbeta receptors between groups. However, the percentage of TGFbeta2 positive fibroblasts was significantly higher in SSc glands compared with controls (p<0.004). RP glands showed an intermediate level of expression. By contrast, a lower percentage of RP fibrolasts expressed TGFbeta3 compared with controls with SSc glands showing an intermediate level of expression. CONCLUSIONS: These results show that (a) there are no changes in glandular expression of tenascin, elastin and fibronectin in SSc and RP and (b) both conditions are associated with an increased salivary gland mast cell population and changes in expression of TGFbeta2 and beta3 isoforms by glandular fibroblasts.

Adult↗
PubMed2000

Comparison of the response of primary murine peritoneal macrophages and the U937 human histiocytic cell line to challenge with in vitro generated clinically relevant UHMWPE particles.

The response of primary murine macrophages and the U937 human histiocytic cell line to challenge with clinically relevant UHMWPE wear debris of known particle size and dose was evaluated. Particles with mean sizes of 0.24, 0.45, 1.71, 7.62 and 88 microm were co-cultured with cells for 24 hours prior to assessment of cell viability and production of the osteolytic mediators IL-1beta, IL-6, TNFalpha and, in supernatants from murine phagocytes, PGE2 and GM-CSF. All particle fractions were evaluated at particle volume (microm3) to cell number ratios of 10 : 1 and 100 : 1 (and, additionally, 0.1 : 1 and 1 : 1 for U937 cells). These ratios had previously been identified as the most stimulatory and clinically relevant. Although the results for the cell line were highly variable, stimulation with phagocytosable particles (range 0.1 to 15 microm) resulted in enhanced levels of cytokine secretion by both murine macrophages and U937 histiocytes. The most biologically active particles were sub-micrometre in size. However, U937 cells responded to wear debris at much lower particle volume to cell number ratios (>0.1 microm3 per cell) than the murine cells (> 10 microm3 per cell). No GM-CSF was produced by particle or LPS stimulated murine macrophages. Similarly, U937 histiocytes failed to secrete any IL-1beta. Neither macrophage population responded to stimulation with the largest (88 microm) particles. These results confirm earlier findings and suggest that the size of UHMWPE wear particles is a critical factor in macrophage activation. Moreover, primary murine macrophages have been demonstrated to be a suitable model for studying cell-particle interactions in vitro.

Animals↗
PubMed1999

Protein kinase C activation downregulates the expression and function of the basolateral Na+/K+/2Cl(-) cotransporter.

The basolateral Na+/K+/2Cl(-) cotransporter (NKCC1) has been shown to be an independent regulatory site for electrogenic Cl(-) secretion. The proinflammatory phorbol ester, phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C (PKC), inhibits basal and cyclic adenosine monophosphate (cAMP)-stimulated NKCC1 activity in T84 intestinal epithelial cells and decreases the steady state levels of NKCC1 mRNA in a time- and dose-dependent manner. The levels of NKCC1 protein also fall in accordance with the NKCC1 mRNA transcript and these levels are unaffected by 4alpha-phorbol, which does not activate PKC. Inhibition of maximal (cAMP-stimulated) NKCC1 functional activity by PMA was first detected by 1 h, whereas decreases in the steady state levels of NKCC1 mRNA were not detectable until 4 h. NKCC1 mRNA expression recovers toward control levels with extended treatment of cells with PMA suggesting that the PMA effects on NKCC1 expression are mediated through activation of PKC. Although NKCC1 mRNA and protein levels return to control values after extended PMA exposure, NKCC1 functional activity does not recover. Immunofluorescence imaging suggest that the absence of functional recovery is due to failure of newly synthesized NKKC1 protein to reach the cell surface. We conclude that NKCC1 has the capacity to be regulated at the level of de novo expression by PKC, although decreased NKCC1 expression alone cannot account for either early or late loss of NKCC1 function.

Carrier Proteins↗
PubMed1999

Monochloramine directly modulates Ca(2+)-activated K(+) channels in rabbit colonic muscularis mucosae.

BACKGROUND & AIMS: Mesenteric ischemia, infection, and inflammatory bowel disease may eventuate in severe colitis, complicated by toxic megacolon with impending intestinal perforation. Monochloramine (NH(2)Cl) is a membrane-permeant oxidant generated during colitis by the large amount of ambient luminal NH(3) in the colon. Reactive oxygen metabolites can modulate smooth muscle ion channels and thereby affect colonic motility, which is markedly impaired in colitis. METHODS: Effects of NH(2)Cl on ionic currents in the innermost smooth muscle layer of the colon, the tunica muscularis mucosae, were examined using the patch clamp technique. Membrane potential in whole tissue strips was measured using high-resistance microelectrodes. RESULTS: Whole cell voltage clamp experiments showed that NH(2)Cl (3-30 micromol/L) enhanced outward currents in a dose-dependent manner, increasing currents more than 8-fold at a test potential of +30 mV. Tail current analysis showed that the currents enhanced by NH(2)Cl were K(+) currents. Inhibition by tetraethylammonium and iberiotoxin suggested that these currents represented activation of large-conductance, Ca(2+)-activated K(+) channels. The membrane-impermeant oxidant taurine monochloramine, however, had no effect on whole cell currents. Single-channel studies in inside-out patches showed that NH(2)Cl increased open probability of a 257-pS channel in symmetrical (140 mmol/L) K(+). In the presence of NH(2)Cl, the steady-state voltage dependence of activation was shifted by -22 mV to the left with no change in the single-channel amplitude. The sulfhydryl alkylating agent N-ethylmaleimide prevented NH(2)Cl-induced channel activation. NH(2)Cl also hyperpolarized intact muscle strips, an effect blocked by iberiotoxin. CONCLUSIONS: NH(2)Cl, at concentrations expected to be found during colitis, may contribute to smooth muscle dysfunction by a direct oxidant effect on maxi K(+) channels.

Animals↗
PubMed1999

TGF-beta receptor expression in human odontoblasts and pulpal cells.

Transforming growth factor-beta (TGF-beta) isoform expression by odontoblasts leads to their sequestration within the dentine matrix, from where they may be released during caries and participate in the reparative processes. Two receptor types for TGF-beta have been implicated in TGF-beta induced signalling. The aim of this study was to characterise immunohistochemically the expression of these receptors in sound and carious human teeth to facilitate our understanding of the ability of these cells to respond to TGF-beta stimulation. Sound and carious human teeth were routinely processed and paraffin sections stained for TGF-beta receptors I and II, using the StrAviGen immunoperoxidase method. Strong specific staining for both receptor types was observed in the odontoblasts of healthy teeth with the greatest intensity seen with receptor I. Staining of weaker intensity was also observed for both receptors in the underlying cell rich area and pulp core. Similar patterns of staining were observed within carious tissues. We conclude that odontoblasts and other cells of the pulp of mature human molar teeth show the presence of both TGF-beta receptors I and II in health and disease with odontoblasts showing the strongest expression. Such findings may be important in the response of these cells to tissue injury.

Activin Receptors, Type I↗
PubMed1999

Prediction and diagnosis of attachment loss by enhanced chemiluminescent assay of crevicular fluid alkaline phosphatase levels.

The current study aimed to apply a novel enhanced chemiluminescence assay in the analysis of gingival crevicular fluid (GCF) alkaline phosphatase (ALP) levels from patients with untreated adult periodontitis. 3666 sites in 25 patients were monitored prior to and after attachment loss was detected with a Florida disc probe. Parameters assessed were, relative attachment level, probing pocket depth, occurrence of bleeding on probing (single episode), GCF volume (microliter), total ALP levels (microIU/30 s sample time) and ALP concentration (IU/l). After recruiting patients to the study, all measures were taken at baseline and 3 months later, prior to the institution of non-surgical periodontal therapy at active sites. Thresholds for determining attachment loss were calculated using a modification of the tolerance method. The mesio-buccal sites of all teeth had GCF samples collected. The size of individual patient thresholds used to define whether attachment loss had occurred, was dependent upon the discomfort felt by that patient during electronic probing, with a positive correlation existing between discomfort on probing (10 cm visual analogue scale) and threshold size (R = 0.52, p < 0.049). A total of 274 sites (7.5%) experienced attachment loss of which 39 sites had GCF samples available for analysis. Total ALP levels were significantly higher at baseline for sites that progressed to attachment loss than paired controls (p < 0.003), but all other parameters showed no differences (p > 0.1). There were significant increases in total ALP levels and GCF volumes for active sites between baseline and 3 month measures (p < 0.01), but not for control sites or test site ALP concentration (p > 0.8). The diagnostic accuracy for GCF ALP as a predictor of future attachment loss (threshold 900 microIU/30 s) was 64%, with +ve and -ve predictive values of 62% and 68%. When a threshold of 1300 microIU/30 s was selected for ALP as a marker of recent or currently active disease, diagnostic accuracy and +ve/-ve predictive values were 77% and 77%/76%, respectively. These results indicate that total GCF ALP levels may serve as a predictor of future or current disease activity.

Adult↗
PubMed1999

Loss of differentiation of 4NQO-induced rat malignant oral keratinocytes correlates with metastatic dissemination and is associated with a reduced cellular response to TGF-beta1 and an altered receptor profile.

This study examined the metastatic capacity of clonal populations of 4NQO-induced rat malignant oral keratinocytes following orthotopic transplantation to athymic mice. Polygonal and spindle cells formed well-differentiated squamous cell carcinomas (keratin positive and vimentin negative) and undifferentiated spindle cell tumours (keratin negative and vimentin positive), respectively, in almost 100% of animals at the site of inoculation (floor of mouth). Transplantation of 5x 10(6) cells of either cell type at high cell density resulted in approximately 50% of animals forming pulmonary metastases. By contrast, inoculation of 2x 10(6) differentiated polygonal cells resulted in the formation of significantly fewer pulmonary metastases than the undifferentiated spindle cells. A single well-differentiated clone of polygonal cells and 3 of 4 of the undifferentiated spindle cell lines produced comparable levels of TGF-beta1. One undifferentiated spindle cell line expressed significantly more TGF-beta1 and, following transplantation orthotopically, fewer animals formed pulmonary metastases despite the formation of primary tumours in almost all grafted animals, suggesting that TGF-beta1 can act as a tumour suppressor in this cell type. All cell lines produced comparable amounts of TGF-beta2. The clones of polygonal cells were markedly inhibited and the spindle cells were only partially inhibited by exogenous TGF-beta1. Both cell types expressed high-affinity TGF-beta cell surface receptors; the ratio of type I to type II TGF-beta receptors was 1.0:<3.0 in the spindle cells and 1.0:17.9 in the polygonal clone. The results suggest that differentiated rat malignant oral keratinocytes are less aggressive and have a decreased potential to metastasise than their undifferentiated spindle cell counterparts. This may be attributable, in part, to a change in TGF-beta receptor profile leading to the partial loss of response to exogenous TGF-beta1.

4-Nitroquinoline-1-oxide↗
PubMed1999

PKC-epsilon regulates basolateral endocytosis in human T84 intestinal epithelia: role of F-actin and MARCKS.

Protein kinase C (PKC) and the actin cytoskeleton are critical effectors of membrane trafficking in mammalian cells. In polarized epithelia, the role of these factors in endocytic events at either the apical or basolateral membrane is poorly defined. In the present study, phorbol 12-myristate 13-acetate (PMA) and other activators of PKC selectively enhanced basolateral but not apical fluid-phase endocytosis in human T84 intestinal epithelia. Stimulation of basolateral endocytosis was blocked by the conventional and novel PKC inhibitor Gö-6850, but not the conventional PKC inhibitor Gö-6976, and correlated with translocation of the novel PKC isoform PKC-epsilon. PMA treatment induced remodeling of basolateral F-actin. The actin disassembler cytochalasin D stimulated basolateral endocytosis and enhanced stimulation of endocytosis by PMA, whereas PMA-stimulated endocytosis was blocked by the F-actin stabilizers phalloidin and jasplakinolide. PMA induced membrane-to-cytosol redistribution of the F-actin cross-linking protein myristoylated alanine-rich C kinase substrate (MARCKS). Cytochalasin D also induced MARCKS translocation and enhanced PMA-stimulated translocation of MARCKS. A myristoylated peptide corresponding to the phosphorylation site domain of MARCKS inhibited both MARCKS translocation and PMA stimulation of endocytosis. MARCKS translocation was inhibited by Gö-6850 but not Gö-6976. The results suggest that a novel PKC isoform, likely PKC-epsilon, stimulates basolateral endocytosis in model epithelia by a mechanism that involves F-actin and MARCKS.

Acetophenones↗
PubMed1999

Effects of substance P on human colonic mucosa in vitro.

Previous studies indicated that the peptide substance P (SP) causes Cl--dependent secretion in animal colonic mucosa. We investigated the effects of SP in human colonic mucosa mounted in Ussing chamber. Drugs for pharmacological characterization of SP-induced responses were applied 30 min before SP. Serosal, but not luminal, administration of SP (10(-8) to 10(-6) M) induced a rapid, monophasic concentration and Cl--dependent, bumetanide-sensitive short-circuit current (Isc) increase, which was inhibited by the SP neurokinin 1 (NK1)-receptor antagonist CP-96345, the neuronal blocker TTX, the mast cell stabilizer lodoxamide, the histamine 1-receptor antagonist pyrilamine, and the PG synthesis inhibitor indomethacin. SP caused TTX- and lodoxamide-sensitive histamine release from colonic mucosa. Two-photon microscopy revealed NK1 (SP)-receptor immunoreactivity on nerve cells. The tyrosine kinase inhibitor genistein concentration dependently blocked SP-induced Isc increase without impairing forskolin- and carbachol-mediated Isc increase. We conclude that SP stimulates Cl--dependent secretion in human colon by a pathway(s) involving mucosal nerves, mast cells, and the mast cell product histamine. Our results also indicate that tyrosine kinases may be involved in this SP-induced response.

Anti-Inflammatory Agents, Non-Steroidal↗