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Biomedical subjects

J B Matthews

Publications and source records attributed to J B Matthews.

At least 55 records · Page 3Linked to original sources
PubMed2001

Immunisation of cattle with recombinant acetylcholinesterase from Dictyocaulus viviparus and with adult worm ES products.

Dictyocaulus viviparus causes a serious lung disease of cattle. For over 30 years, a radiation-attenuated larval vaccine has been used with success; however, this vaccine has several disadvantages. A more stable vaccine against D. viviparus, capable of stimulating prolonged protective immunity, would be beneficial. Recent research has been directed at adult worm ES components that may be involved in parasite survival in the host. One component is the secreted enzyme, acetylcholinesterase (AChE), a target for circulating antibody in infected calves. Here, we describe a study where protection was investigated in calves immunised with either native adult ES products or a recombinant parasite AChE. These antigens were administered twice with Freund's incomplete adjuvant. Subsequently, all calves were challenged with 700 L3 and their worm burdens and immune responses compared with those in calves that received an anthelmintic-abbreviated infection and challenge control calves. Significant levels of protection were not obtained in the immunised groups but significant immunity was achieved in the calves that received the anthelmintic abbreviated infection. Antibody responses amongst the groups were different, with significantly higher IgG1 responses in the immune, infected group and in adult ES recipients. Significantly higher IgG2 responses were found in the latter group. Following challenge, the groups that received the abbreviated infection and the fusion protein produced specific antibody that bound the native enzyme. No differences were observed between groups in peripheral blood mononuclear cell responsiveness to either antigen. However, adult ES products appeared to have a mitogenic effect on these cells, whilst the fusion protein exhibited an inhibitory effect. These results suggest that in this form, AChE is not a potential vaccine candidate and that adult ES products, in contrast to previous experiments in guinea pigs, do not contain protective components.

Acetylcholinesterase↗
PubMed2001

Evaluation of the specificity of five oligoprobes for identification of cyathostomin species from horses.

Here, we report evaluation of five oligoprobes designed from intergenic spacer (IGS) region sequences for identification of cyathostomin species. Oligoprobes were designed for identification of Cylicocyclus ashworthi, Cylicocyclus nassatus, Cylicostephanus longibursatus, Cylicostephanus goldi and a fifth probe designed to identify all members of this tribe. PCR amplification of IGS DNA from 16 cyathostomin species allowed sequence comparison and identification of four putative species-specific probes. Southern blotting of amplified products from 16 species showed that all probes were species-specific. The fifth probe recognised all 16 cyathostomin species but did not bind to members of the genus Strongylus. Furthermore, these probes were used to identify individual infective L3, eggs and L4 indicating that they will be invaluable to furthering the study of the epidemiology and pathogenesis of these important equine nematodes.

Animals↗
PubMed2001

An evaluation of the capacity of differently prepared demineralised bone matrices (DBM) and toxic residuals of ethylene oxide (EtOx) to provoke an inflammatory response in vitro.

Demineralised bone matrix (DBM) is a form of allogeneic tissue graft widely used in oral and maxillofacial procedures. There is a long history of controversy relating to the suitability of ethylene oxide gas (EtOx) as a terminal sterilisation agent for this graft, relating to its effects on the clinical performance of the grafts. Furthermore, the generation of a toxic residual chemical (ethylene chlorohydrin, ECl) during the ethylene oxide sterilisation of patellar tendon allografts has been implicated in the failure of these grafts owing to the induction of a localised inflammatory response. In this study we have investigated the capacity of a range of different DBM preparations, and ECl dilutions, to induce the production of three pro-inflammatory cytokines, interleukin-6 (IL-6), interleukin-1beta (IL-1beta), and tumour necrosis factor alpha (TNF-alpha) from human peripheral blood mononuclear cells (PBMNCs). The levels of EtOx and ECl in EtOx terminally sterilised DBM and mineralised bone grafts were measured by gas chromatography. It was found that the only factor capable of rendering DBM pro-inflammatory was the presence of small (<20 micrometre diameter) DBM particles. No other processing or sterilisation technique resulted in the DBM becoming pro-inflammatory. Although it was also found that DBM, when EtOx-sterilised, retained more ECI than mineralised bone grafts following a standard EtOx sterilisation protocol, ECl did not provoke an inflammatory response in vitro at levels up to and including those which are cytotoxic to PBMNCs.

Bone Demineralization Technique↗
PubMed2001

Percutaneous treatment of a pancreatic fistula after pancreaticoduodenectomy.

Breakdown of the pancreaticojejunal anastomosis after a Whipple procedure is reported to occur in as many as 15% of cases. Intraoperative placement of a drain adjacent to the anastomosis is performed to allow the creation of a controlled pancreaticocutaneous fistula in the event of an anastomotic disruption. The authors present a case of successful percutaneous treatment of a disrupted pancreaticojejunal anastomosis. This was achieved with use of the resulting pancreaticocutaneous fistula for access to restore internal drainage, followed by fistula occlusion with use of gelatin pledgets.

Anastomosis, Surgical↗
PubMed2001

In vitro and in vivo interactions of bisphenol A and its metabolite, bisphenol A glucuronide, with estrogen receptors alpha and beta.

The estrogenic activities of bisphenol A (BPA) and its major metabolite BPA glucuronide (BPA-G) were assessed in a number of in vitro and in vivo assays. BPA competed with [3H]-17beta-estradiol (E2) for binding to mouse uterine cytosol ER, a glutathione S-transferase (GST)-human ER D, E, and F domain fusion protein (GST-hERalphadef) and full-length recombinant hERbeta. The IC(50) values for E2 were similar for all three receptor preparations, whereas BPA competed more effectively for binding to hERbeta (0.96 microM) than to either mouse uterine cytosol ER (26 microM) or GST-hERalphadef (36 microM). In contrast, BPA-G did not competitively displace [3H]E2 from any of the ER preparations. In MCF-7 cells transiently transfected with Gal4-hERalphadef or Gal4-hERbetadef, BPA induced reporter gene activity with comparable EC(50) values (71 and 39 microM, respectively). No significant induction of reporter gene activity was seen for BPA-G. Cotreatment studies showed that concentrations of (10 microM) BPA and BPA-G did not antagonize E2-induced luciferase mediated through either Gal4-hERalphadef or Gal4-hERbetadef. In vivo, the uterotropic effect of gavage or subcutaneous (sc) administration of 0.002-800 mg of BPA/kg of body weight/day for three consecutive days was examined in immature rats. Dose-related estrogenic effects on the rat uterus were observed at oral doses of 200 and 800 mg/kg and at sc doses of 10, 100, and 800 mg/kg. These results demonstrate that BPA competes more effectively for binding to ERbeta, but induces ERalpha- and ERbeta-mediated gene expression with comparable efficacy. In contrast, BPA-G did not exhibit any in vitro estrogenic activity. In addition, there was a clear route dependency on the ability of BPA to induce estrogenic responses in vivo.

Animals↗
PubMed2001

Comparison of the response of three human monocytic cell lines to challenge with polyethylene particles of known size and dose.

The response of three human monocytic cell lines (Monomac-1, U937 and THP-1) to challenge with polyethylene particles of known size and dose was evaluated. Particles with a mean size of 0.21, 0.49, 4.3, 7.2, and 88 microm were co-cultured with the cells for 24 hours prior to the assessment of cell viability and production of the pro-inflammatory cytokines, IL-1beta, IL-6 and TNFalpha. Additionally, GM-CSF and prostaglandin E2 were measured in culture supernatants from particle stimulated U937 cells. All particle fractions were evaluated at particle volume (microm3) to cell number ratios of 100 : 1, 10 : 1, 1 : 1 and 0.1 : 1. None of the test fractions had any effect on cell viability. Only the response of the U937 cell line was demonstrated to be comparable to that of primary macrophages as determined in a previous study. Furthermore only particle volume to cell number ratios of 10 : 1 or greater consistently stimulated significantly enhanced levels of cytokine secretion with particles within the phagocytosable size range (0.1 to 10 microm) being the most biologically active. No response was observed when U937 macrophages were stimulated with the largest (88 microm) particles at any of the volume ratios tested in this study. These results suggest that the size and volume of polyethylene particles are critical factors in macrophage activation. In addition, the U937 cell line has been shown to be a suitable model for the in vitro study of macrophage-particle interactions.

Journal Article↗
PubMed2001

TGF-beta isoforms and TGF-beta receptors in drug-induced and hereditary gingival overgrowth.

Drug therapy and hereditary factors are two of the main causes of gingival overgrowth (GO). Both of these forms of GO are associated with increased extracellular matrix production by fibroblasts. Transforming growth factor beta (TGF-beta) is an important mediator of wound healing and tissue regeneration, which stimulates fibroblasts to produce extracellular matrix materials. The aim of this immunohistochemical study was to determine whether there is any altered expression of TGF-beta isoforms or its receptors in tissue from patients with drug-induced GO (DIGO; n=10) and hereditary gingival fibromatosis (n=10) when compared to non-overgrowth tissue (n=10). Compared to control tissues, significantly more fibroblasts expressed TGF-beta1 in both DIGO and hereditary gingival fibromatosis tissues (P<0.03). Cells expressing TGF-beta2 were present at control levels in DIGO but were significantly reduced in hereditary gingival fibromatosis (P<0.02). By contrast, the number of TGF-beta3-positive cells was the same in overgrowth tissues and controls. However, because of differences in total fibroblast densities between groups, there was a proportional increase in TGF-beta3 as well as TGF-beta1 expressing cells within both overgrowth populations (P<0.0001). Furthermore, representation of the TGF-beta2-positive phenotype was reduced in hereditary gingival fibromatosis (P<0.01) but increased in DIGO (P<0.005) compared to controls. Absorbance measurements of the positive cell populations showed that the level of expression was significantly higher for TGF-beta1 in hereditary gingival fibromatosis (P<0.002) and significantly lower for TGF-beta3 in DIGO (P<0.03). No significant differences in the numbers of TGF-betaRI- or RII-positive cells were detected between overgrowth tissues and controls. However, there were increases in the proportion of receptor-positive cells in the total cell population analysed in overgrowth tissues (P<0.0001). These results indicate qualitative and quantitative differences in TGF-beta isoform and receptor expression by fibroblasts in gingival overgrowth that may contribute to disease pathogenesis.

Adolescent↗
PubMed2001

Current status of medical and surgical therapy for obesity.

The incidence of obesity (especially childhood obesity) and its associated health-related problems have reached epidemic proportions in the United States. Recent investigations suggest that the causes of obesity involve a complex interplay of genetic, environmental, psychobehavioral, endocrine, metabolic, cultural, and socioeconomic factors. Several genes and their protein products, such as leptin, may be particularly important in appetite and metabolic control, although the genetics of human obesity appear to involve multiple genes and metabolic pathways that require further elucidation. Severe obesity is frequently associated with significant comorbid medical conditions, including coronary artery disease, hypertension, type II diabetes mellitus, gallstones, nonalcoholic steatohepatitis, pulmonary hypertension, and sleep apnea. Long-term reduction of significant excess weight in these patients may improve or resolve many of these obesity-related health problems, although convincing evidence of long-term benefit is lacking. Available treatments of obesity range from diet, exercise, behavioral modification, and pharmacotherapy to surgery, with varying risks and efficacy. Nonsurgical modalities, although less invasive, achieve only relatively short-term and limited weight loss in most patients. Currently, surgical therapy is the most effective modality in terms of extent and duration of weight reduction in selected patients with acceptable operative risks. The most widely performed surgical procedure, Roux-en-Y gastric bypass, achieves permanent (followed up for more than 14 years) and significant weight loss (more than 50% of excess body weight) in more than 90% of patients.

Anastomosis, Roux-en-Y↗
PubMed2001

Protein kinase epsilon dampens the secretory response of model intestinal epithelia during ischemia.

BACKGROUND: Luminal fluid sequestration and diarrhea are early manifestations of mesenteric ischemia. This can be modeled in vitro with the use of T84 intestinal epithelia, where ischemia induces Cl(-) secretion with adenosine-mediated autocrine feedback. Protein kinase C (PKC) regulates epithelial transport and, in some organ systems, is involved in the response to ischemic stress. The purpose of this study was to define the role of PKC on epithelial transport during ischemia. METHODS: By voltage-current clamp, short-circuit current (Isc) equals Cl(-) secretion. Ischemic conditions were simulated with the use of a well-established chemical hypoxia protocol. RESULTS: Chemical hypoxia briskly activated Isc. Gö6850, an antagonist of novel and conventional PKC isoforms, markedly enhanced the ischemia-induced Isc response, although Gö6976 (which inhibits only conventional isoforms) had no effect. Rottlerin, a specific inhibitor of PKC delta, did not attenuate ischemic Isc. Both phorbol 12-myristate, 13-acetate and bryostatin-1, which selectively activate PKC epsilon in T84 cells, markedly attenuated the Isc response to ischemia. Both agents also inhibited the Isc response to exogenous adenosine. CONCLUSIONS: PKC (likely the novel epsilon isoform) in intestinal epithelia modulates ischemia-induced alterations in ion transport. Inhibition of PKC epsilon exaggerates the secretory response that is induced by ischemia and by authentic adenosine; conversely, augmented activation of PKC epsilon inhibits secretion. Manipulation of PKC epsilon could limit luminal fluid sequestration during mesenteric ischemia.

Biological Transport↗
PubMed2001

Hydroxylated benzo[a]pyrene metabolites are responsible for in vitro estrogen receptor-mediated gene expression induced by benzo[a]pyrene, but do not elicit uterotrophic effects in vivo.

The estrogenic activities of benzo[a]pyrene (B[a]P) and 10 metabolites (1, 3-, 7-, and 9-hydroxy-B[a]P; 4,5-, 7,8-, and 9,10-dihydrodihydroxy-B[a]P; and 1,6-, 3,6-, and 6,12-B[a]P-dione) were investigated. In vitro, B[a]P did not displace tritiated 17beta-estradiol ([3H]E2) from either a bacterially expressed fusion protein consisting of glutathione-S:-transferase linked to the D, E, and F domains of human ERalpha (GST-hERalphadef), or from full-length human ERbeta (hERbeta) at concentrations as high as 60 microM. However, 10 microM B[a]P demonstrated partial agonist activity in human Gal4-ERalphadef and mouse Gal4-ERbetadef reporter gene assays in transiently transfected MCF-7 cells, relative to 10 nM E2. 1-, 3-, 7-, and 9-hydroxy-B[a]P were found to bind to both receptor isoforms, each showing a higher affinity for the beta isoform. At 10 microM the four monohydroxylated metabolites were able to induce Gal4-hERalphadef- and Gal4-mERbetadef-mediated reporter gene expression to levels 20-100% of that caused by 10 nM E2, suggesting that these metabolites, and not the parent compound, induced reporter gene expression following B[a]P treatment of transiently transfected MCF-7 cells. In addition, the effect of B[a]P on two estrogen-inducible end points, uterine weight and lactoferrin mRNA levels, was determined in ovariectomized DBA/2 and C57BL/6 mice. Neither orally administered B[a]P at doses as high as 10 mg/kg body weight nor subcutaneously injected 3- or 9-hydroxy-B[a]P at doses as high as 20 mg/kg induced effects on uterine wet weight or uterine lactoferrin mRNA levels in either strain. These data suggest that B[a]P metabolites that are estrogenic at high concentrations in vitro do not induce estrogenic effects in the mouse uterus.

Animals↗
PubMed2001

Regulation of epithelial transport and barrier function by distinct protein kinase C isoforms.

The phorbol ester phorbol 12-myristate 13-acetate (PMA) inhibits Cl(-) secretion (short-circuit current, I(sc)) and decreases barrier function (transepithelial resistance, TER) in T84 epithelia. To elucidate the role of specific protein kinase C (PKC) isoenzymes in this response, we compared PMA with two non-phorbol activators of PKC (bryostatin-1 and carbachol) and utilized three PKC inhibitors (Gö-6850, Gö-6976, and rottlerin) with different isozyme selectivity profiles. PMA sequentially inhibited cAMP-stimulated I(sc) and decreased TER, as measured by voltage-current clamp. By subcellular fractionation and Western blot, PMA (100 nM) induced sequential membrane translocation of the novel PKC epsilon followed by the conventional PKC alpha and activated both isozymes by in vitro kinase assay. PKC delta was activated by PMA but did not translocate. By immunofluorescence, PKC epsilon redistributed to the basolateral domain in response to PMA, whereas PKC alpha moved apically. Inhibition of I(sc) by PMA was prevented by the conventional and novel PKC inhibitor Gö-6850 (5 microM) but not the conventional isoform inhibitor Gö-6976 (5 microM) or the PKC delta inhibitor rottlerin (10 microM), implicating PKC epsilon in inhibition of Cl(-) secretion. In contrast, both Gö-6976 and Gö-6850 prevented the decline of TER, suggesting involvement of PKC alpha. Bryostatin-1 (100 nM) translocated PKC epsilon and PKC alpha and inhibited cAMP-elicited I(sc). However, unlike PMA, bryostatin-1 downregulated PKC alpha protein, and the decrease in TER was only transient. Carbachol (100 microM) translocated only PKC epsilon and inhibited I(sc) with no effect on TER. Gö-6850 but not Gö-6976 or rottlerin blocked bryostatin-1 and carbachol inhibition of I(sc). We conclude that basolateral translocation of PKC epsilon inhibits Cl(-) secretion, while apical translocation of PKC alpha decreases TER. These data suggest that epithelial transport and barrier function can be modulated by distinct PKC isoforms.

Biological Transport↗
PubMed2001

Trans-dentinal stimulation of tertiary dentinogenesis.

Trans-dentinal stimulation of tertiary dentinogenesis has long been recognized, and has traditionally been ascribed to diffusion of irritant substances arising during injury and restorative treatment. Identification of bio-active components, especially growth factors including TGF-beta s, sequestered within dentin matrix provides a new explanation for cellular signaling during tertiary dentinogenesis. Both isolated dentin matrix components and pure growth factors (TGF-beta s) have been shown to signal cellular events leading to reactionary and reparative tertiary dentinogenesis. Release of these bio-active components from dentin matrix may arise during carious attack and other injury to the tissue, and also during subsequent surgical intervention and restoration of the tooth. Both cavity-conditioning agents and leaching from restorative materials may contribute to release of these components. Distance of diffusion, as determined by cavity residual dentin thickness, and other restorative parameters may influence the signaling process after release of these components. Careful consideration of the interplay between tissue injury and surgical and restorative material factors is required for optimum exploitation of the exquisite regenerative capacity of dentin-pulp for more biological approaches to clinical treatment of dental disease.

Animals↗
PubMed2001

A novel method for the prediction of functional biological activity of polyethylene wear debris.

The comparative performance of artificial hip joints has been extensively investigated in vitro through measurements of wear volumes. In vivo a major cause of long-term failure is wear-debris-induced osteolysis. These adverse biological reactions are not simply dependent on wear volume, but are also controlled by the size and volumetric concentration of the debris. A novel model is presented which predicts functional biological activity; this is determined by integrating the product of the biological activity function and the volumetric concentration function with the wear volume over the whole particle size range. This model combines conventional wear volume measurements with particle analysis and the output from in vitro cell culture studies to provide a new indicator of osteolytic potential. The application of the model is demonstrated through comparison of the functional biological activity of wear debris from polyethylene acetabular cups articulating under three different conditions in a hip joint simulator.

Biocompatible Materials↗
PubMed2001

A novel three-dimensional tissue equivalent model to study the combined effects of cyclic mechanical strain and wear particles on the osteolytic potential of primary human macrophages in vitro.

The effects of cyclic mechanical strain and challenge with physiologically relevant doses of submicrometre-size polyethylene (PE) particles on the osteolytic potential of primary human mononuclear phagocytes were investigated. Cells were seeded into a three-dimensional tissue matrix and co-cultured with particles (mean size 0.21 microm) at particle volume to cell number ratios of 7.5, 15, 30 and 100 microm3/cell. Matrices were then either cultured statically or subjected to 20 per cent cyclic compressional strain in the 'ComCell' for 16 h prior to the assessment of cell viability and quantification of the pro-inflammatory cytokine tumour necrosis factor alpha (TNFalpha). The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazdium bromide) assay was shown to be too insensitive to detect changes in cell viability. However, when quantified by the adenosine triphosphate (ATP) assay, cell viability was demonstrated to be reduced following exposure to cyclic strain. Macrophages cultured in the static three-dimensional tissue equivalent model produced very high levels of TNFalpha in response to submicrometre PE particles at a ratio of 100 microm3/cell. Cyclic strain in the absence of particles gave only a small increase in TNFa production. However, the combined effects of strain and particle stimulation at a ratio of 30 microm3/cell resulted in the secretion of significantly more TNFalpha than was produced by macrophages subjected to strain alone, or the cells-only control. This synergy between cyclic strain and PE particle stimulation was only evident when the volume of particles was reduced below the volume that maximally stimulated cells. These results suggest that while cyclic strain may not be the primary factor responsible for macrophage activation and periprosthetic osteolysis, at low particle load, it may contribute significantly to the osteolytic potential of macrophages in vitro or in vivo.

Coculture Techniques↗
PubMed2000

Quantification of rainbow trout (Oncorhynchus mykiss) zona radiata and vitellogenin mRNA levels using real-time PCR after in vivo treatment with estradiol-17 beta or alpha-zearalenol.

Estrogen receptor-mediated induction of zona radiata (ZR) and vitellogenin (VTG) mRNA and protein in rainbow trout (Oncorhynchus mykiss) was compared to assess their utility as biomarkers for exposure to estrogenic compounds. Partial sequences of rainbow trout ZR and beta-actin were cloned by reverse transcriptase polymerase chain reaction (RT-PCR) using degenerate primers based on conserved regions across a number of species. A 549 bp fragment of the rainbow trout ZR-gene showed a high degree of amino acid sequence identity to that of salmon (77%), winter flounder (64%), carp ZP2 (63%) and medaka (61%) ZR-proteins. The 1020 bp beta-actin fragment was approximately 100% identical to sequences from several species. Real-time PCR was used to quantify the induction of ZR-gene and VTG in rainbow trout liver after in vivo exposure to estradiol-17 beta (E(2)) (0.01, 0.1, 1.0 or 10 mg/kg body weight (bw) fish) or alpha-zearalenol (alpha-ZEA) (0.1, 1.0 or 10 mg/kg bw). Real-time PCR and indirect enzyme-linked immunosorbent assay (ELISA) showed that ZR and VTG were induced in both the liver and the plasma after a single injection of E(2) or alpha-ZEA. ZR was more responsive to low levels of E(2) and alpha-ZEA than VTG, and real-time PCR was shown to be more sensitive than the ELISA. Rainbow trout ZR-gene and proteins provide a sensitive biomarker for assessing estrogenic activity.

Actins↗
PubMed2000

Effect of size and dose on bone resorption activity of macrophages by in vitro clinically relevant ultra high molecular weight polyethylene particles.

Polyethylene wear debris generated at the bearing surfaces of total artificial hip joints is thought to play an important role in the periprosthetic osteolysis and ultimately the aseptic loosening of these prostheses. The macrophage is believed to be central to this process by releasing various cytokines and other mediators of osteolysis upon phagocytosis of the polyethylene wear debris. This study evaluated the in vitro bone resorption response of C3H murine peritoneal macrophages to clinically relevant GUR 1120 polyethylene particles. Macrophages were co-cultured in vitro with GUR 1120 particles with a mean size of 0.24, 0.45, 1.71, and 7.62, and GUR 1120 polyethylene resin with a mean size of 88 microm at various particle volume (microm)(3): macrophage ratios (0.1:1; 1:1; 10:1; and 100:1). The conditioned supernatants were incubated with (45)calcium radio-labeled mouse calvariae, and bone resorption was measured as (45)calcium release. The results showed that the 0.24 microm particles stimulated the macrophages to generate bone resorbing activity at a ratio of 10(microm)(3) per macrophage. The 0.45 and 1.71 microm particles were active at a ratio of 100( microm)(3) per macrophage, and the 7.62 and 88 microm particles were inactive at all the doses tested. The co-culture supernatants were also assayed for TNF-alpha, IL-1beta, IL-6, and PGE(2). The results followed the same trend for particle size and volume dose to that observed for the bone resorbing activity. This study has demonstrated, for the first time, the importance of size and dose of clinically relevant polyethylene particles on the osteolytic response of macrophages in vitro.

Animals↗