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Biomedical subjects

Leslie G Cleland

Publications and source records attributed to Leslie G Cleland.

At least 19 recordsLinked to original sources
PubMed2006

Importance of the carboxyl terminus of FAT/CD36 for plasma membrane localization and function in long-chain fatty acid uptake.

This study investigates the role of the cytoplasmic C terminus of fatty acid translocase (FAT/CD36) in localization of the molecule to the plasma membrane, its insertion into lipid rafts, and its ability to enhance long-chain fatty acid uptake in transfected H4IIE rat hepatoma cells. In these cells, wild-type FAT/CD36 is localized to both lipid raft and nonraft domains of the plasma membrane. Interestingly, a FAT/CD36 truncation mutant lacking the final 10 amino acids of the cytoplasmic C terminus was retained within the cell in detergent-resistant membranes, and unlike wild-type FAT/CD36, it did not enhance oleate uptake. Furthermore, expression of FAT/CD36 in these cells increased the incorporation of oleate into diacylglycerol, a property that was not shared by truncated FAT/CD36. To examine whether the C terminus itself has an intrinsic ability to dictate the plasma membrane localization of FAT/CD36, this region was fused in-frame to enhanced green fluorescent protein (EGFP). This domain was sufficient to attach EGFP to cellular membranes, suggesting an involvement in the intracellular traffic of the molecule. We conclude that the C terminus of FAT/CD36 is required for localization of the receptor to the cell surface and its ability to enhance cellular oleate uptake.

Animals↗
PubMed2006

Endothelial cell COX-2 expression and activity in hypoxia.

The clinical experience with selective cyclooxygenase (COX)-2 inhibitors reveals there are important protective roles for COX-2 in the cardiovascular system. This study examined the response to hypoxia of endothelial cell eicosanoid synthesis with respect to the role of COX-2 and its molecular regulation in hypoxia. Human umbilical vein endothelial cells (HUVEC) were exposed to hypoxia and the effects on COX-2, prostacyclin (PGI(2)) and thromboxane (TXA(2)) synthesis were examined. COX-2 promoter constructs were used to examine the role of Hypoxia Inducible Factors (HIFs) in COX-2 responses to hypoxia. Hypoxia caused an increase in PGI(2) synthesis, but not TXA(2) synthesis. PGI(2), but not TXA(2) synthesis, was absolutely dependent on upregulation of COX-2 by hypoxia. Mutations of transcription factor binding sites in the promoter showed a lack of involvement of NFkappaB in the response to hypoxia, but suggested involvement of HIFs. Transfection of HUVEC with HIF expression vectors increased activity of the promoter construct and increased native COX-2 expression in normoxia. EMSA showed HIF binding in nuclear extracts of hypoxic HUVEC to a region of the COX-2 promoter. The endothelial cell response to hypoxia involves increased production of the anti-thrombotic eicosanoid, PGI(2), which is dependent on COX-2 upregulation by a HIF-mediated process.

6-Ketoprostaglandin F1 alpha↗
PubMed2006

A system for improving vitamin D nutrition in residential care.

OBJECTIVE: To assess the feasibility of administering an inexpensive preparation of vitamin D(3) 100 000 IU orally 3 monthly to aged-care residents. DESIGN: Prospective, controlled open-label implementation trial. SETTING: Residential aged care, November 2003 to May 2004 (primary study). PARTICIPANTS: 137 ambulant residents: 107 treated (mean age, 85 years; 79 were women), 30 untreated controls (mean age, 87 years; 22 were women). INTERVENTIONS: Lactose microencapsulated vitamin D(3) 100 000 IU orally at baseline, then 3 monthly (three or more doses); untreated subjects were observed contemporaneously. MAIN OUTCOME MEASURES: Serum levels of 25-hydroxyvitamin D [25(OH)D] at 6 months compared with baseline; acceptability of the program to residents and staff. RESULTS: At baseline, 95% of residents assessed (n = 137) had serum 25(OH)D levels below the desirable range of 60-160 nmol/L. At 6 months, all treated residents (n = 98) achieved desired levels, with the mean (+/- SD) 25(OH)D level increasing from 36.4 +/- 12.6 nmol/L (range, 12-75 nmol/L) at baseline to 124.0 +/- 27.9 nmol/L (range, 68-244 nmol/L). In no resident did 25(OH)D approach toxic levels. The mean serum 25(OH)D level remained low in the control group (n = 27): 42.8 +/- 18.3 nmol/L (range, 18-98 nmol/L). The difference between the mean 25(OH)D levels of treatment and control groups at 6 months was 81.2 nmol/L (95% CI, 69.7-92.0 nmol/L). The cost of the supplement was $4 per resident per annum. Substudies showed mean trough serum 25(OH)D levels in the desired range at 3 months (n = 31), but below the desired range at 6 months (n = 50). Subjects given 3-monthly doses for up to 2 years maintained serum 25(OH)D levels within the desired range, with no trend toward undesirable accumulation (n = 11). CONCLUSIONS: Vitamin D(3) 100 000 IU given orally 3 monthly is a practical, safe, effective and inexpensive way to meet the vitamin D(3) requirements of aged-care residents.

Administration, Oral↗
PubMed2006

Reduction of cardiovascular risk factors with longterm fish oil treatment in early rheumatoid arthritis.

OBJECTIVE: Rheumatoid arthritis (RA) is associated with increased risk for cardiovascular (CV) events through multiple factors. Fish oil has been shown to reduce symptoms in RA and to reduce CV risk. We assessed the effect of an antiinflammatory dose of fish oil on CV risk factors within a program of combination chemotherapy for patients with early RA. METHODS: Patients who chose not to take fish oil (n = 13) were compared with patients who achieved a sustained elevation of eicosapentaenoic acid (EPA) in plasma phospholipid fatty acids (> 5% total fatty acids) while taking fish oil over a 3-year period (n = 18). We examined cellular content of arachidonic acid (AA), synthesis of thromboxane A2 and prostaglandin E2, use of nonsteroidal antiinflammatory drugs (NSAID), traditional CV lipid risk factors, and disease activity at 3 years. RESULTS: At 3 years, AA (as a proportion of AA plus long-chain n-3 fatty acids that can compete with AA for cyclooxygenase metabolism) was 30% lower in platelets and 40% lower in peripheral blood mononuclear cells in subjects taking fish oil. Serum thromboxane B2 was 35% lower and lipopolysaccharide-stimulated whole-blood prostaglandin E2 was 41% lower with fish oil ingestion compared to no fish oil. NSAID use was reduced by 75% from baseline with fish oil (p < 0.05) and by 37% without fish oil (NS). Favorable changes in fasting blood lipids were seen with, but not without fish oil. Remission at 3 years was more frequent with fish oil use (72%) compared to no fish oil (31%). CONCLUSION: Fish oil reduces cardiovascular risk in patients with RA through multiple mechanisms.

Adult↗
PubMed2006

Recruitment and proliferation of CD4+ T cells in synovium following adoptive transfer of adjuvant-induced arthritis.

Adjuvant-induced arthritis can be transferred to naive Dark Agouti (DA) strain (DA.CD45.1) rats by thoracic duct (TD) lymphocytes. Disease can be re-induced in convalescent rats by further transfer of arthritogenic cells, suggesting that resolution of the adoptive disease is not due to active regulation. To examine whether resolution is due to exhaustion of effector cells, we transferred the disease to DA.CD45.1 recipients, using CD4+ T cells from DA.CD45.2 donors. At the height of the adoptively transferred disease, donor cells comprised only 5-10% of recirculating CD4+ T cells but they accounted for approximately 40% of the CD4+ T cells in synovium-rich tissues of the hind paws. Approximately 65% of the donor cells in the synovium expressed a marker of proliferation (Ki-67 antigen). Division of CD4+ T cells continued in shielded paws after suppression of the recirculating pool of lymphocytes by selective irradiation. Intravenously injected CD4+ TD T lymphoblasts from arthritic donors were recruited to normal paws and, in greater numbers, to paws of animals with existing arthritis. Survival of the [125I]iodo-deoxyuridine-labeled lymphoblasts was greater in animals with existing arthritis. We conclude that effector CD4+ T cells in target tissues can proliferate in response to autoantigens and exhibit enhanced survival. However, without a continuous supply, adoptively transferred effector cells do not produce autonomous local disease, due to limits to their lifespan and ability to replicate indefinitely.

Adjuvants, Immunologic↗
PubMed2006

Early combination disease modifying antirheumatic drug treatment for rheumatoid arthritis.

Most people presenting with rheumatoid arthritis today can expect to achieve disease suppression, can avoid or substantially delay joint damage and deformities, and can maintain a good quality of life. Optimal management requires early diagnosis and treatment, usually with combinations of conventional disease modifying antirheumatic drugs (DMARDs). If these do not effect remission, biological DMARDs may be beneficial. Lack of recognition of the early signs of rheumatoid arthritis, ignorance of the benefits of early application of modern treatment regimens, and avoidable delays in securing specialist appointments may hinder achievement of best outcomes for many patients. Triage for recognising possible early rheumatoid arthritis must begin in primary care settings with the following pattern of presentation as a guide: involvement of three or more joints; early-morning joint stiffness of greater than 30 minutes; or bilateral squeeze tenderness at metacarpophalangeal or metatarsophalangeal joints.

Antirheumatic Agents↗
PubMed2006

Cyclooxygenase-2 inhibitors: what went wrong?

PURPOSE OF REVIEW: This review describes the biology underpinning the development of selective cyclooxygenase-2 inhibitors, documenting the clinical experience from the pivotal gastrointestinal safety trials to their eventual withdrawal or labelling with cardiovascular safety warnings. RECENT FINDINGS: The elucidation of differences between the active sites of cyclooxygenase-1 and cyclooxygenase-2 allowed the targeted design of the selective cyclooxygenase-2 inhibitors known as coxibs. These were developed and marketed as non-steroidal anti-inflammatory drugs (NSAIDs) that had improved upper gastrointestinal safety compared with older non-selective NSAIDs. A large-scale study with arthritis patients to evaluate upper gastrointestinal safety, however, demonstrated that celecoxib was not superior in terms of upper gastrointestinal safety compared with the older non-selective NSAIDs that were used as comparators. In an equally large study with arthritis patients, a more selective cyclooxygenase-2 inhibitor, rofecoxib, did have improved upper gastrointestinal safety compared with the non-selective non-steroidal anti-inflammatory drug naproxen. Although concomitant clinical trial evidence emerged that rofecoxib increased cardiovascular risk, this was discounted by its pharmaceutical company owner. Despite the lack of improved upper gastrointestinal safety with celecoxib and the evidence of cardiovascular risk with rofecoxib, both agents had widespread clinical use for 4-5 years. This was not diminished by the publication of plausible eicosanoid-based biological mechanisms whereby selective cyclooxygenase-2 inhibition could increase cardiovascular risk. Finally, clinical trials involving patients with colorectal cancer and post-operative pain revealed increased cardiovascular risk with all members of this class of drug. SUMMARY: These events provide a case study of a failure of the medical journal literature to guide drug usage.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2006

Fish oil: what the prescriber needs to know.

There is a general belief among doctors, in part grounded in experience, that patients with arthritis need nonsteroidal anti-inflammatory drugs (NSAIDs). Implicit in this view is that these patients require the symptomatic relief provided by inhibiting synthesis of nociceptive prostaglandin E2, a downstream product of the enzyme cyclo-oxygenase (COX), which is inhibited by NSAIDs. However, the concept of 'safe' NSAIDs has collapsed following a multiplicity of observations establishing increased risk for cardiovascular events associated with NSAID use, especially but not uniquely with the new COX-2-selective NSAIDs. This mandates greater parsimony in the use of these agents. Fish oils contain a natural inhibitor of COX, reduce reliance on NSAIDs, and reduce cardiovascular risk through multiple mechanisms. Fish oil thus warrants consideration as a component of therapy for arthritis, especially rheumatoid arthritis, in which its symptomatic benefits are well established. A major barrier to the therapeutic use of fish oil in inflammatory diseases is ignorance of its mechanism, range of beneficial effects, safety profile, availability of suitable products, effective dose, latency of effects and instructions for administration. This review provides an evidence-based resource for doctors and patients who may choose to prescribe or take fish oil.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2006

Public funding of bosentan for the treatment of pulmonary artery hypertension in Australia: cost effectiveness and risk sharing.

OBJECTIVES: In Australia, no therapeutic agents were subsidised for the treatment of idiopathic pulmonary artery hypertension (iPAH), a rare progressive and severe disease with short life expectancy, until 1 March 2004, when bosentan (a dual endothelin receptor antagonist of high cost) was listed on the Pharmaceutical Benefits Scheme (PBS). Bosentan, in addition to conventional therapy, has been shown to slow iPAH progression and improve clinical and haemodynamic status and symptomatology, compared with placebo and conventional therapy. The objective of this paper is to describe the process of the Australian Pharmaceutical Benefits Scheme listing for bosentan (Tracleer), which included a health economic model assessing the cost effectiveness of bosentan from a healthcare payer perspective, and a risk-sharing arrangement based on the establishment of a patient registry. METHODS: The health economic model predicted the cost, hospitalisation and mortality rates of a population of iPAH patients treated with either the conventional therapy regimen used in Australia or bosentan plus the conventional therapy regimen. The model was implemented as a first-order Monte Carlo simulation with mortality modelled directly as the main clinical outcome. The impacts of proposed continuation criteria, restricting the ongoing use of the drug, were evaluated. Costs and outcomes were discounted at 5% and a sensitivity analysis examined the robustness of the key assumptions. RESULTS: The model predicted that after 5, 10 and 15 years, the difference in average cumulative costs between bosentan plus conventional therapy and conventional therapy alone would be 116,929 Australian dollars (A dollars), A181,808 dollars and A216,331 dollars for each patient, respectively. There would be an associated increase in average life expectancy of 1.39, 2.93 and 3.87 years at 5, 10 and 15 years, respectively, with an incremental cost-effectiveness ratio at 15 years of A55,927 dollars for each life-year gained. Removing the continuation criteria from the model increased the incremental cost-effectiveness ratio to A62,267 dollars (1996-2002 values). CONCLUSIONS: Economic modelling based on improved survival suggests bosentan to be a potentially cost-effective treatment for iPAH. However, the structure of the model and its inputs should be reviewed and updated as more data become available.

Antihypertensive Agents↗
PubMed2005

MHC II+ CD45+ cells from synovium-rich tissues of normal rats: phenotype, comparison with macrophage and dendritic cell lineages and differentiation into mature dendritic cells in vitro.

Synovial tissues are frequent sites of inflammatory disorders in which dendritic cells (DCs) may play an important role. This study examines potential antigen-presenting cells obtained from synovium-rich tissues (SRTs) by vascular perfusion of rat hind limbs with collagenase and further enzymatic digestion of the disarticulated hind paws in vitro. The three sub-populations of interest were: CD45+MHC IIhi, mainly CD11c+ and CD163-; CD45+MHC IIlo, mainly CD11c- and CD163+ and CD45+MHC II-, mainly CD11c- and CD163+. Expression of CD11c and CD163 correlated with ruffled cell-surface (CD11c+CD163-) and highly vacuolated cytoplasm (CD11c-CD163+), respectively. Culture of the CD45+CD163- sub-population in granulocyte macrophage colony-stimulating factor (GM-CSF) yielded CD45+MHC IIhi CD11c+CD163- cells with veiled morphology, while the large vacuolated cells that expressed CD163 resembled type A synoviocytes in both surface antigen phenotype and morphology. These results demonstrate that SRTs contain indeterminate cells that can differentiate into mature DCs in vitro in response to GM-CSF, plus mature synovial lining macrophages.

Animals↗
PubMed2005

MHC class II compartment, endocytosis and phagocytic activity of macrophages and putative dendritic cells isolated from normal tissues rich in synovium.

The endocytic and phagocytic activities of a population of MHC IIhi CD11c+ dendritic cell (DC)-like cells in synovium-rich tissues (SRTs) of normal rat paws were compared with CD163+ cells (putative macrophages) from the same tissues and pseudo-afferent lymph DCs, peritoneal macrophages and blood monocytes. Fifty percent of CD11c+ cells and 75% of CD163+ cells isolated from SRT internalized fluorescein-conjugated dextran (FITC-DX). Of these endocytic cells, half of those expressing CD11c, but only 30% of those expressing CD163, were surface MHC class II+ (sMHC II+). CD11c+ cells were more endocytic than monocytes or pseudo-afferent lymph DC, but some CD163+ cells (type A synoviocytes) were found to be highly endocytic. CD163+ cells from SRT were more phagocytic (25%) than the general MHC class II+ population (16%). Of phagocytic cells, 40% of CD163+ cells were sMHC II(variable) and they constituted 60% of all MHC class II+ phagocytic cells. Only 18% of phagocytic MHC II+ cells expressed CD11c and the most of these were MHC IIhi. In comparison, 60% of CD163+ peritoneal macrophages were phagocytic, while blood monocytes were poorly phagocytic. Intracellular MHC class II-rich compartments (MIIC) were prominent in sMHC IIhi cells in SRT but rare in CD163+ cells. Most MHC IIhi CD11c+ cells did not have a detectable MIIC.

Animals↗
PubMed2005

Paradoxical effect of n-3-containing vegetable oils on long-chain n-3 fatty acids in rat heart.

Flaxseed, echium, and canola oils contain alpha-linolenic acid (18:3n-3, ALA) in a range of concentrations. To examine their effect on elevating cardiac levels of long-chain n-3 FA, diets based on these n-3-containing vegetable oils were fed to rats for 4 wk. Sunflower oil, which contains little ALA, was a comparator. Despite canola oil having the lowest ALA content of the three n-3-containing vegetable oils, it was the most potent for elevating DHA (22:6n-3) levels in rat hearts and plasma. However, the relative potencies of the dietary oils for elevation of EPA (20:5n-3) in heart and plasma followed the same rank order as their ALA content, i.e., flaxseed > echium > canola > sunflower oil. This paradox may be explained by lower ALA intake leading to decreased competition for Delta6 desaturase activity between ALA and the 24:5n-3 FA precursor to DHA formation.

Animals↗
PubMed2005

Diet and rheumatoid arthritis: a review of the literature.

INTRODUCTION: Rheumatoid arthritis is a common inflammatory condition. A large number of patients seek alternative or complementary therapies of which diet is an important component. This article reviews the evidence for diet in rheumatoid arthritis along with the associated concept of oral tolerization. METHODS: References were taken from Medline from 1966 to September 2004. The keywords, rheumatoid arthritis, diet, n-3 fatty acids, vitamins, and oral tolerization, were used. RESULTS: Randomized controlled trials (RCTs) indicate that dietary supplementation with n-3 fatty acids provides modest symptomatic benefit in groups of patients with rheumatoid arthritis. Epidemiological studies and RCTs show cardiovascular benefits in the broader population and patients with ischemic heart disease. A number of mechanisms through which n-3 fats may reduce inflammation have been identified. In a small number of patients with rheumatoid arthritis, other dietary manipulation such as fasting, vegan, and elimination diets may have some benefit. However, many of these diets are impractical or difficult to sustain long term. CONCLUSIONS: Dietary manipulation provides a means by which patients can a regain a sense of control over their disease. Dietary n-3 supplementation is practical and can be easily achieved with encapsulated or, less expensively, bottled fish oil.

Arthritis, Rheumatoid↗
PubMed2005

Blockade of IFN-gamma does not affect the arthritogenicity of T cells generated during the induction of adjuvant arthritis but exacerbates the polyarthritis produced by adoptive transfer of arthritogenic effector cells.

IFN-gamma production is prominent in some models of autoimmune disease, including adjuvant arthritis (AA), but the role of IFN-gamma in the pathogenesis of these diseases is uncertain. Experimental manipulation (administration of cytokine, blocking cytokine action with specific antibody, disruption of genes encoding the cytokine or its receptor) has revealed both pro- and anti-inflammatory effects, depending on the nature of the manipulation and the timing of the treatment. We examined separately the effects of cytokine blockade during the afferent and efferent phases of AA in Dark Agouti rats, using an adoptive transfer system. Effects of IFN-gamma on the efferent phase were investigated by treating recipients with mAb DB-1, which blocks the activity of rat IFN-gamma. When treatment was commenced before cell transfer, the resulting polyarthritis was more severe than in controls treated with normal IgG. Commencing treatment after the adoptively transferred disease had become established caused neither amelioration nor exacerbation, but did cause some delay in resolution. In contrast, treatment of donors did not appear to affect the generation of arthritogenic cells. The main effect of IFN-gamma appears to be modulation of the arthritogenicity of the migratory effector T cells that can transfer AA.

Adoptive Transfer↗
PubMed2004

Effects of hypoxia on the expression and activity of cyclooxygenase 2 in fibroblast-like synoviocytes: interactions with monocyte-derived soluble mediators.

OBJECTIVE: Rheumatoid synovium is characterized by hyperplasia of fibroblast-like (type B) synoviocytes (FLS), infiltration with mononuclear leukocytes, and tissue hypoxia. Although the latter is well documented, it has received little attention in dissection of the biochemical events that mediate the inflammatory lesion in rheumatoid arthritis (RA). Therefore, this study was designed to assess the effect of hypoxia on FLS responses to the monokine interleukin-1beta (IL-1beta) and to monocyte conditioned medium. METHODS: FLS obtained from serial cultures of synovial fluid aspirates were treated with IL-1beta or monocyte conditioned medium, under normoxia and hypoxia. RESULTS: In hypoxia, transcription of cyclooxygenase 2 (COX-2), expression of COX-2 protein, and production of COX-2-derived eicosanoids and matrix metalloproteinase (MMP) activity by FLS were all increased in response to IL-1beta. In contrast to our recent observations concerning monocytes, there was no change in COX-2 message stability and cytosolic phospholipase A2 activity in the FLS under hypoxia. Treatment of monocyte conditioned medium with an IL-1beta blocking antibody showed that most of the effect of the conditioned medium was attributable to IL-1beta. CONCLUSION: The findings suggest that hypoxia is an important factor in aggravating the inflammatory lesion in RA, through increased production of COX-2-derived nociceptive eicosanoids and increased release of tissue-damaging MMPs.

Arthritis, Rheumatoid↗
PubMed2004

Interleukin-17: the missing link between T-cell accumulation and effector cell actions in rheumatoid arthritis?

The prominence of T cells and monocyte/macrophages in rheumatoid synovium suggests T cells may localize and amplify the effector functions of monocyte/macrophages in rheumatoid disease. However, while T cells are abundant in rheumatoid joints, classic T-cell derived cytokines are scarce, especially when compared to the levels of monokines IL-1 beta and TNF-alpha. For this reason, it has been speculated that monocyte/macrophages may act independently of T cells in rheumatoid disease and that the role of T cells may be more or less irrelevant to core disease mechanisms. The question of T-cell influence requires re-evaluation in light of the characterization of IL-17, a T-cell derived cytokine that is abundant in rheumatoid synovium and synovial fluid. IL-17 has a number of pro-inflammatory effects, both directly and through amplification of the effects of IL-1 beta and TNF-alpha. IL-17 is able to induce expression of pro-inflammatory cytokines and stimulate release of eicosanoids by monocytes and synoviocytes. Furthermore, IL-17 has been implicated in the pathogenesis of inflammatory bone and joint damage through induction of matrix metalloproteinases and osteoclasts, as well as inhibition of proteoglycan synthesis. In animal models of arthritis, intra-articular injection of IL-17 results in joint inflammation and damage. The recognition of IL-17 as a pro-inflammatory T cell derived cytokine, and its abundance within rheumatoid joints, provides the strongest candidate mechanism to date through which T cells can capture and localize macrophage effector functions in rheumatoid arthritis. As such, IL-17 warrants consideration for its potential as a therapeutic target in rheumatoid arthritis.

Animals↗