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Biomedical subjects

M R Duncan

Publications and source records attributed to M R Duncan.

At least 19 recordsLinked to original sources
PubMed2003

Etoricoxib in the treatment of chronic pain.

For the many patients who suffer chronic pain, we seek the most effective anti-inflammatory drug with the least side-effect profile and the greatest long-term safety. Etoricoxib, a selective COX2 inhibitor, has been shown to be as effective as non-selective non-steroidal anti-inflammatory drugs in the management of chronic pain in rheumatoid arthritis and osteoarthritis, for periods of up to one year. Data on etoricoxib efficacy in chronic low back pain is beginning to emerge. The side-effect profile of etoricoxib suggests it is well tolerated with similar adverse effects to non-selective NSAIDs. Larger studies are awaited, to see whether superior gastrointestinal tolerability can be proven. Further work will be required to show that etoricoxib is safe in patients with pre-existing cardiovascular or gastrointestinal comorbidity, and the potentially confounding role of aspirin still needs to be elucidated. However, etoricoxib shows promise as a new and effective COX2 inhibitor in clinical practice.

Adult↗
PubMed1999

Connective tissue growth factor mediates transforming growth factor beta-induced collagen synthesis: down-regulation by cAMP.

Connective tissue growth factor (CTGF) is a cysteine-rich peptide synthesized and secreted by fibroblastic cells after activation with transforming growth factor beta (TGF-beta) that acts as a downstream mediator of TGF-beta-induced fibroblast proliferation. We performed in vitro and in vivo studies to determine whether CTGF is also essential for TGF-beta-induced fibroblast collagen synthesis. In vitro studies with normal rat kidney (NRK) fibroblasts demonstrated CTGF potently induces collagen synthesis and transfection with an antisense CTGF gene blocked TGF-beta stimulated collagen synthesis. Moreover, TGF-beta-induced collagen synthesis in both NRK and human foreskin fibroblasts was effectively blocked with specific anti-CTGF antibodies and by suppressing TGF-beta-induced CTGF gene expression by elevating intracellular cAMP levels with either membrane-permeable 8-Br-cAMP or an adenylyl cyclase activator, cholera toxin (CTX). cAMP also inhibited collagen synthesis induced by CTGF itself, in contrast to its previously reported lack of effect on CTGF-induced DNA synthesis. In animal assays, CTX injected intradermally in transgenic mice suppressed TGF-beta activation of a human CTGF promoter/lacZ reporter transgene. Both 8-Br-cAMP and CTX blocked TGF-beta-induced collagen deposition in a wound chamber model of fibrosis in rats. CTX also reduced dermal granulation tissue fibroblast population increases induced by TGF-beta in neonatal mice, but not increases induced by CTGF or TGF-beta combined with CTGF. Our data indicate that CTGF mediates TGF-beta-induced fibroblast collagen synthesis and that in vivo blockade of CTGF synthesis or action reduces TGF-beta-induced granulation tissue formation by inhibiting both collagen synthesis and fibroblast accumulation.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1998

Determining the capability of a drug product to be terminally sterilized: a case study involving a heat-sensitive, oxygen-sensitive drug product.

A decision scheme for determining the capability of a finished product dosage form to be terminally sterilized was presented and followed for a heat-sensitive, oxygen-sensitive drug product (DP). Studies were conducted first in a laboratory steam sterilizer and then in a production unit. When a nonheat-sensitive steam sterilization cycle produced unfavorable loss of potency and increases in the amount of impurities, a new heat-sensitive steam sterilization cycle was investigated. An acceptable product was produced by reducing the headspace oxygen level and reducing the heat delivered to the product during terminal sterilization. The amount of sterilizing steam heat delivered to the product was reduced by reducing the allowable temperature range from set-point of the terminal steam sterilizer, and by developing a new heat-sensitive cycle. The heat-sensitive cycle, with a model based upon a known relationship of the biological indicator, product D value, and the environmental bioburden, can achieve a 10(-6) sterility assurance level when it delivers an F0 > or = 4 min. When the standard terminal sterilization model and cycle produced unacceptable levels of degradation, formulation/production changes, and terminal sterilization model and cycle modifications were explored, before the DP was directed to aseptic filling. Acceptable moist heat terminal sterilization the DP was then achieved.

Drug Stability↗
PubMed1997

Effect of social deprivation on disease severity and outcome in patients with rheumatoid arthritis.

OBJECTIVE: Social deprivation is now recognised to have an important impact on morbidity and mortality. This study sought to ascertain the effect of deprivation, if any, on disease severity, functional disability, and outcome in rheumatoid patients in Glasgow. METHODS: 814 patients with rheumatoid arthritis (RA) were assessed for clinical, functional, and laboratory indices of disease activity. Deprivation categories for individual patients were determined using the Carstairs index. Five year follow up is available for 440 patients. RESULTS: The study population of RA patients live largely in the most deprived areas. Patients from deprived areas have significantly poorer function at outset and at five years as defined by the Health Assessment Questionnaire (HAQ) score. This is not attributable to differences in disease duration in patients from the most deprived regions or compliance with treatment. Furthermore, these patients do not achieve over five years the initial functional level of those living in the most advantaged localities. CONCLUSION: RA patients from deprived areas have poorer function, which is associated with greater need--medical, social, and paramedical. Strategies and resources for healthcare need to be adjusted according to this variation.

Adult↗
PubMed1996

The use of antimalarials in combination with other disease modifying agents in RA--the British experience.

Antimalarial drugs are effective disease modifying agents in RA with a low incidence of serious toxic effects. Recently, combinations of second-line agents have been used in RA in attempts to treat patients with no response to a number of single agents, or suboptimal response to a single agent. Combinations of drugs have been selected for maximum efficacy and minimum toxicity, but clinical trials are difficult to design and interpret. In particular, ensuring adequate power to detect small differences in response poses a major problem. Antimalarials are an attractive choice for combination therapy due to their efficacy, mechanisms of action and toxicity profile. In this review, the evidence for the use of antimalarials in combination in RA is examined. No advantage has been shown in combining antimalarials with gold, penicillamine or sulphasalazine compared with monotherapeutic regimens. There is some evidence to suggest a beneficial combination of antimalarials with methotrexate, but this is as yet inconclusive. Open non-randomised uncontrolled studies have shown that antimalarials combined with cytotoxic agents are effective but highly toxic. The authors conclude that there is little good evidence to support the introduction of combination second-line drug therapy for RA into widespread therapeutic use.

Antimalarials↗
PubMed1995

Pentoxifylline, pentifylline, and interferons decrease type I and III procollagen mRNA levels in dermal fibroblasts: evidence for mediation by nuclear factor 1 down-regulation.

Pentoxifylline (PTX) is a methylxanthine that exhibits multiple biologic activities, including the inhibition of collagen synthesis by dermal fibroblasts. Because some PTX activities have recently been linked to transcription factor-mediated regulation of gene transcription, we have investigated if PTX acts to inhibit collagen synthesis at a transcriptional locus by measuring procollagen mRNA levels by assaying for the presence of an activator of procollagen gene promoters, nuclear factor (NF)-1. The effects of another methylxanthine, pentifylline (PTF), shown herein to be a tenfold more potent inhibitor of collagen synthesis than PTX, and interferon-alpha, -beta, and -gamma were studied in parallel. Analysis of extracellular protein and RNA from 48-h-treated fibroblasts showed that PTX, PTF, and interferons decreased alpha 1(I), alpha 2(I), and alpha 1(III) procollagens by reducing the steady-state levels of the corresponding procollagen mRNA transcripts. Reduction of procollagen mRNA levels appeared to be dependent on new protein synthesis, as it was prevented by treatment with cycloheximide. Assay for the presence of nuclear NF-1 by gel mobility shift analysis showed that extracts from interferon, PTX, and PTF-treated fibroblasts lacked proteins recognizing the consensus DNA binding sequence for NF-1. Taken together, these observations suggest interferons and methylxanthines may inhibit fibroblast collagen synthesis by a common mechanism requiring new protein synthesis that suppresses procollagen gene transcription through down-regulation of NF-1.

Adult↗
PubMed1995

Oncostatin M stimulates collagen and glycosaminoglycan production by cultured normal dermal fibroblasts: insensitivity of sclerodermal and keloidal fibroblasts.

It is thought that normal fibrotic repair progresses to dermal fibrosis when fibroblasts are activated persistently by chronic exposure to cytokines such as transforming growth factor-beta. However, additional cytokines and mechanisms may play a role in the development of fibrosis. Thus, we examined a recently described T-lymphocyte/macrophage-derived cytokine, oncostatin M, for its effect on the production of collagen and glycosaminoglycan by microcultures of normal dermal, sclerodermal, and keloidal fibroblasts. Treatment with oncostatin M for 48 h induced dose-dependent (1-100 ng/ml) increases in the collagen and glycosaminoglycan production of nine normal fibroblast strains, which in the absence of fetal bovine serum at 100 ng/ml averaged 196% and 244%, respectively. Oncostatin M treatment increased both types I and III procollagens and their mRNA transcripts, as well as levels of hyaluronic acid, chondroitin-4/6 sulfates, and dermatan sulfate, but not fibronectin or general noncollagenous protein synthesis. In contrast, the collagen production of six of eight sclerodermal and keloidal fibroblast strains was essentially unresponsive to oncostatin M treatment, with 100 ng/ml inducing an average increase of only 34% for the eight fibrotic strains. Oncostatin M stimulation of fibrotic fibroblast glycosaminoglycan production was also hyporesponsive, as 100 ng/ml of oncostatin M induced an average increase of only 101%. These results indicate that oncostatin M could function as a stimulator of normal fibrotic repair via activation of fibroblast collagen and glycosaminoglycan synthesis and that the persistent activation of sclerodermal and keloidal fibroblasts is accompanied by a loss of sensitivity to oncostatin M stimulation.

Adult↗
PubMed1995

Mononuclear cells isolated from fibrotic skin lesions in avian scleroderma constitutively produce fibroblast-activating cytokines and immunoglobulin M.

University of California, Davis line 200 and 206 chickens develop an inherited autoimmune fibrotic disease associated with autoantibodies and other features similar to human scleroderma. Early in life, line 200/206 chickens develop mononuclear cell (MNC) infiltrates in the skin, followed by severe dermal fibrosis and vascular occlusions. Cultured fibroblasts derived from fibrotic skin lesions of line 200/206 chickens display an activated phenotype producing elevated quantities of collagen and glycosaminoglycan (GAG) compared to fibroblasts derived from normal chicken skin. To demonstrate a link between skin mononuclear cell infiltration and fibroblast activation, we cultured MNC isolated from developing fibrotic skin lesions, normal appearing skin, and peripheral blood of line 206 chickens for 24-72 h. Subsequent assay of MNC culture supernatants for effect on the collagen and GAG production of normal chicken skin fibroblasts demonstrated that only fibrotic lesion MNC supernatants contained significant collagen and GAG synthesis stimulatory activity. Both stimulatory activities were constitutively produced, undialyzable, heat and protease sensitive, and coeluted on gel filtration with a M(r) of 24-32 kD. Gel filtration also revealed that fibrotic lesion MNC secrete a protein > 250 kD, which we have identified as immunoglobulin (Ig) M by Western blot analysis. These results demonstrate that skin infiltrating MNC secrete both fibroblast-activating cytokines and IgM and thus they likely play an important role as effector cells in the development of dermal fibrosis and autoantibodies in this avian model of scleroderma.

Animals↗
PubMed1993

Nonradioactive gel mobility shift assay using chemiluminescent detection.

A nonradioactive gel mobility shift assay using chemiluminescent detection following semidry transfer to nylon membranes is described. The procedure utilizes digoxigenin-labeled oligonucleotides in conjunction with anti-digoxigenin antibody Fab fragments coupled to alkaline phosphatase. Detection of alkaline phosphatase is by autoradiography of the chemiluminescence produced during enzymatic dephosphorylation of a dioxetane substrate. This method offers similar sensitivity to radioactive methods while having the advantages of multiple exposures, faster processing, stability of labeled oligonucleotides and safety associated with nonradioactive methods of detection.

DNA-Binding Proteins↗
PubMed1992

Cultured fibroblasts in avian scleroderma, an autoimmune fibrotic disease, display an activated phenotype.

University of California, Davis, line 200 and 206 chickens spontaneously develop an autoimmune syndrome that has many features analogous to human scleroderma, including dermal fibrosis, antinuclear antibodies and antibodies to type II collagen. These birds also have thymic subcapsular epithelial defects and an abnormality in T cell calcium influx and proliferation in response to both T cell receptor-dependent and -independent activators. To determine whether fibroblast activation is a contributing factor to development of skin fibrosis in line 200/206 chickens, as it is in human scleroderma, we studied the collagen, non-collagenous protein and glycosaminoglycan (GAG) production of 34 separate fibroblast lines derived from the normal and fibrotic skin of line 200 and 206 chickens and from the skin of control chicken lines 058 and 254. The mean +/- SEM 24-h incorporation of 3H-proline or 3H-glucosamine into extracellular collagen, non-collagenous protein or GAG by first passage fibroblast lines derived from the fibrotic skin of diseased birds was 1,526 +/- 136, 859 +/- 82 and 25.7 +/- 1.3 dpm/10(3) cells, respectively, while fibroblast lines derived from the skin of control birds produced only 341 +/- 36, 343 +/- 42 and 15.2 +/- 1.4 dpm/10(3) cells. Similar differences in results were recorded for cell-associated production, and when collagen and non-collagenous protein production were assessed using non-radioactive electrophoretic methods. The activated phenotype of the fibroblast lines derived from the fibrotic skin of diseased birds persisted through 10 cell doublings in tissue culture. However, the ratio of type I:III collagen and the profile of GAG types produced were similar in all fibroblast lines studied. These results suggest that fibroblast activation is responsible for the skin fibrosis observed in this avian model of scleroderma.

Animals↗
PubMed1992

Pentoxifylline inhibits certain constitutive and tumor necrosis factor-alpha-induced activities of human normal dermal fibroblasts.

Pentoxifylline (PFN), analog of theobromine, which phenotypically and functionally alters various cell types including dermal fibroblasts, has been reported to inhibit tumor necrosis factor-alpha (TNF alpha) activation of neutrophils. We investigated the ability of PFN to alter constitutive and TNF alpha-induced biosynthetic activities of human normal dermal fibroblasts. The sixteenfold increase over constitutive intracellular 2'-5' oligo-adenylate synthetase (2'-5' A synthetase) activity induced by TNF alpha (400 U/ml) failed to occur when PFN (1 mg/ml) was added prior to cytokine treatment. This loss of biologic activity paralleled a reduction in 2'-5' A synthetase proteins and 2'-5' A synthetase-specific m-RNA. PFN failed to inhibit constitutive or TNF alpha-induced IL-6 hybridoma proliferative activity, IL-6 protein, or IL-6-specific m-RNA levels. The presence of PFN (1 mg/ml) in fibroblast cultures reduced constitutive synthesis of collagen and glycosaminoglycan (GAG) by 87% and 45%, respectively, and blocked induction of their synthesis by TNF alpha (10(4) U/ml). Total non-collagenous protein synthesis was not inhibited following PFN treatment (1 mg/ml). PFN did not inhibit TNF alpha induction of only those biosynthetic activities also susceptible to PFN in the constitutive state, with PFN failing to reduce constitutive collagenolytic activity but reducing TNF alpha-induced enhanced collagenolytic activity by 26% and collagenase m-RNA by 51%. Furthermore, PFN did inhibit, by 98%, TNF alpha-dependent murine and human fibroblast cytotoxicity. The selective nature of PFN inhibition of certain TNF alpha activities, the failure of PFN (1 mg/ml) to alter constitutive and TNF alpha-induced levels of type 1 and 2 TNF alpha receptor m-RNA, and the finding that PFN-treated fibroblasts express a similar number of receptors, of similar molecular weight and high affinity for TNF alpha as control, untreated cells, suggest that inhibitory activities of PFN are mediated at a locus other than receptors for TNF alpha.

2',5'-Oligoadenylate Synthetase↗
PubMed1991

Stimulation of collagen and glycosaminoglycan production in cultured human adult dermal fibroblasts by recombinant human interleukin 6.

Interleukin (IL) 6 is a pleiotropic cytokine synthesized by fibroblasts in response to many stimuli, including IL-1 beta. To evaluate the possibility that previously observed stimulation of fibroblast biosynthetic functions by IL-1 beta may be mediated by autocrine IL-6, we investigated the effect of recombinant human (rh) IL-6 on the connective tissue-related biosynthetic functions of three lines of cultured human adult dermal fibroblasts. We found that rhIL-6 mimicked some of the activities of IL-1 beta, as 24-96-h treatment of confluent fibroblast cultures with rhIL-6 caused concentration (10 to 1000 ng/ml)-dependent increases in the production of collagen and the glycosaminoglycans (GAG), hyaluronic acid and chondroitin-4/6-sulfates, but had little effect on fibronectin or total protein production. Although the effective stimulating concentrations of IL-6 were within the range (approximately 100 ng/ml) we found produced by rhIL-1 beta-treated fibroblast cultures, rhIL-1 beta at 0.2-1.0 ng/ml induced significantly greater amounts of collagen and GAG than the maximum effective concentrations of IL-6. Moreover, an anti-rhIL-6 antibody, which effectively neutralized the fibroblast-stimulating activities of rhIL-6, only fractionally blocked the fibroblast-stimulating actions of rhIL-1 beta, suggesting autocrine IL-6 only partially mediates the effects of IL-1 beta on fibroblasts. Conversely, the fibroblast-stimulating effects of rhIL-6 are unlikely due to autocrine IL-1 beta, as an anti-rhIL-1 beta antibody had only minimal inhibitory action on rhIL-6-treated fibroblast cultures. Overall these results suggest that IL-6 could function as a paracrine/autocrine regulator of dermal fibrotic repair.

Adult↗
PubMed1991

Regulation of the proliferation and biosynthetic activities of cultured human Peyronie's disease fibroblasts by interferons-alpha, -beta and -gamma.

To determine the therapeutic potential of interferon (IFN) treatment for Peyronie's disease, we investigated the effect of human recombinant (hu-r) IFNs on cultured fibroblasts derived from a Peyronie's disease penile plaque. Treatment of cultured fibroblasts with hu-r-IFN-alpha2b, hu-r-IFN-beta-ser17 and hu-r-IFN gamma caused a concentration dependent inhibition of both fibroblast proliferation and collagen production, as well as an increase in collagenase production. Hu-r-IFN-alpha and beta had no effect on fibroblast glycosaminoglycan (GAG) or fibronectin production, while hu-r-IFN-gamma markedly increased both GAG and fibronectin production. These results demonstrate that IFNs, especially IFNs-alpha and beta, exhibit antifibrotic activity on Peyronie's disease fibroblasts and suggest a rationale for using IFNs to treat Peyronie's disease.

Cell Division↗
PubMed1990

Urinary cytokines following photodynamic therapy for bladder cancer. A preliminary report.

This preliminary study was undertaken to test for the presence of urinary cytokines whose detection would provide evidence in support of the theory that photodynamic therapy (PDT) produces an immunologic response in patients treated for bladder cancer. Gamma interferon, interleukin 1-beta, interleukin 2, and tumor necrosis factor-alpha were assayed for in the urine of 4 patients treated with photodynamic therapy for bladder cancer, in 7 control patients undergoing transurethral surgical procedures, and in 5 healthy control subjects. Quantifiable concentrations of all cytokines, except gamma interferon, were measured in urine samples from the PDT patients with the highest light energies, while no urinary cytokines were found in the PDT patient who received the lowest light energy nor in any of the control subjects. These findings suggest that a local immunologic response may occur following PDT for bladder cancer.

Adult↗
PubMed1990

Pentoxifylline inhibits the proliferation of human fibroblasts derived from keloid, scleroderma and morphoea skin and their production of collagen, glycosaminoglycans and fibronectin.

Pentoxifylline, an analogue of the methylxanthine theobromine, inhibits the proliferation and certain biosynthetic activities of fibroblasts derived from normal human skin. Fibroblasts from the skin of patients with keloids, scleroderma and morphoea were cultured in vitro in the presence and absence of pentoxifylline (100-1000 micrograms/ml) to determine whether it inhibits fibroblast proliferation and the production of collagen, glycosaminoglycans (GAG), fibronectin and collagenase activity. The exposure of subconfluent fibroblast cultures to pentoxifylline resulted in non-lethal, dose-dependent reductions in serum-driven fibroblast proliferation, with 1000 micrograms/ml pentoxifylline virtually negating the proliferative effect of serum on the cells. The fibroblasts assayed as confluent cultures produced reduced amounts, by up to 95%, of collagen and GAG, dependent on the concentration of pentoxifylline, both in the presence and absence of serum. Pentoxifylline similarly inhibited the fibronectin production by keloid and scleroderma fibroblasts, but had no effect on collagenase activity.

Cell Division↗
PubMed1989

Differential regulation of glycosaminoglycan, fibronectin, and collagenase production in cultured human dermal fibroblasts by interferon-alpha, -beta, and -gamma.

In order to determine whether interferons (IFNs) play a universal role in terminating the fibrotic response by inhibiting other fibroblast functions in addition to growth and collagen production, we investigated the effect of human recombinant (hu-r) IFN-alpha, -beta, and -gamma on the glycosaminoglycan, fibronectin, and collagenase production of cultured human dermal fibroblasts. Our results show that short-term (48 h) treatment of confluent fibroblast cultures with hu-r-IFN-alpha 2 and hu-r-IFN-beta-ser17 causes a concentration (1 to 1 x 10(5) U/ml)-dependent inhibition of glycosaminoglycan production, has no effect on fibronectin production, and markedly increases collagenase production. In contrast, hu-r-IFN-gamma not only causes a concentration-dependent increase in collagenase production but also increases both glycosaminoglycan and fibronectin production. These results demonstrate that IFNs differently regulate fibroblast functions rather than universally inhibit all functions, and show that IFN-alpha and -beta exhibit a broader antifibrotic spectrum that IFN-gamma.

Cells, Cultured↗
PubMed1989

Short-term keloid treatment in vivo with human interferon alfa-2b results in a selective and persistent normalization of keloidal fibroblast collagen, glycosaminoglycan, and collagenase production in vitro.

Two intralesional injections of interferon alfa-2b (1.5 million U per injection) into a progressively enlarging keloid resulted in a 41% reduction in its area. Fibroblasts cultured from the keloid before and 9 days after the initial injection were compared with fibroblasts cultured from the patient's normal skin with respect to proliferation and production of connective tissue matrix components and collagenase. There were no significant differences in the in vitro doubling times of keloidal fibroblasts before (p greater than 0.2) and after (p greater than 0.5) treatment with interferon alfa-2b, as well as of normal fibroblasts, in subconfluent cultures. Multiple passages of keloidal fibroblasts before interferon alfa-2b therapy assayed as confluent cultures produced more collagen (171%, 187%, and 204%), more glycosaminoglycans (153% and 141%), and less collagenase (26% and 31%) than the patient's own normal fibroblasts. In contrast, keloidal fibroblasts after interferon alfa-2b therapy persistently produced normal or subnormal amounts of collagen (107%, 73%, and 64%) and glycosaminoglycans (97% and 96%) and normalized levels of collagenase activity (96% and 86%). Normal amounts of fibronectin were produced by keloidal fibroblasts before and after treatment with interferon alfa-2b.

Cell Division↗