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Biomedical subjects

W Clark

Publications and source records attributed to W Clark.

At least 19 recordsLinked to original sources
PubMed2006

A systematic review of the effectiveness of adalimumab, etanercept and infliximab for the treatment of rheumatoid arthritis in adults and an economic evaluation of their cost-effectiveness.

OBJECTIVES: This report reviews the clinical effectiveness and cost-effectiveness of adalimumab, etanercept and infliximab, agents that inhibit tumour necrosis factor-alpha (TNF-alpha), when used in the treatment of rheumatoid arthritis (RA) in adults. DATA SOURCES: Electronic databases were searched up to February 2005. REVIEW METHODS: Systematic reviews of the literature on effectiveness and cost-effectiveness were undertaken and industry submissions to the National Institute for Health and Clinical Excellence (NICE) were reviewed. Meta-analyses of effectiveness data were also undertaken for each agent. The Birmingham Rheumatoid Arthritis Model (BRAM), a simulation model, was further developed and used to produce an incremental cost-effectiveness analysis. RESULTS: Twenty-nine randomised controlled trials (RCTs), most of high quality, were included. The only head-to-head comparisons were against methotrexate. For patients with short disease duration (<or=3 years) who were naïve to methotrexate, adalimumab was marginally less and etanercept was marginally more effective than methotrexate in reducing symptoms of RA. Etanercept was better tolerated than methotrexate. Both adalimumab and etanercept were more effective than methotrexate in slowing radiographic joint damage. Etanercept was also marginally more effective and better tolerated than methotrexate in patients with longer disease durations who had not failed methotrexate treatment. Infliximab is only licensed for use with methotrexate. All three agents, either alone (where so licensed) or in combination with ongoing disease-modifying antirheumatic drugs (DMARDs), were effective in reducing the symptoms and signs of RA in patients with established disease. At the licensed dose, the numbers needed to treat (NNTs) (95% CI) required to produce an American College for Rheumatology (ACR) response compared with placebo were: ACR20: adalimumab 3.6 (3.1 to 4.2), etanercept 2.1 (1.9 to 2.4), infliximab 3.2 (2.7 to 4.0); ACR50: adalimumab 4.2 (3.7 to 5.0), etanercept 3.1 (2.7 to 3.6), infliximab 5.0 (3.8 to 6.7); and ACR70: adalimumab 7.7 (5.9 to 11.1), etanercept 7.7 (6.3 to 10.0), infliximab 11.1 (7.7 to 20.0). In patients who were naïve to methotrexate, or who had not previously failed methotrexate treatment, a TNF inhibitor combined with methotrexate was significantly more effective than methotrexate alone. Infliximab combined with methotrexate had an increased risk of serious infections. All ten published economic evaluations met standard criteria for quality, but the incremental cost-effectiveness ratios (ICERs) ranged from being within established thresholds to being very high because of varying assumptions and parameters. All three sponsors who submitted economic models made assumptions favourable to their product. BRAM incorporates improvements in quality of life and mortality, but assumes no effect of TNF inhibitors on joint replacement. For use in accordance with current NICE guidance as the third DMARD in a sequence of DMARDs, the base-case ICER was around pound30,000 per quality-adjusted life-year (QALY) in early RA and pound50,000 per QALY in late RA. Sensitivity analyses showed that the results were sensitive to the estimates of Health Assessment Questionnaire (HAQ) progression while on TNF inhibitors and the effectiveness of DMARDs, but not to changes in mortality ratios per unit HAQ. TNF inhibitors are most cost-effective when used last. The ICER for etanercept used last is pound24,000 per QALY, substantially lower than for adalimumab ( pound30,000 per QALY) or infliximab ( pound38,000 per QALY). First line use as monotherapy generates ICERs around pound50,000 per QALY for adalimumab and etanercept. Using the combination of methotrexate and a TNF inhibitor as first line treatment generates much higher ICERs, as it precludes subsequent use of methotrexate, which is cheap. The ICERs for sequential use are of the same order as using the TNF inhibitor alone. CONCLUSIONS: Adalimumab, etanercept and infliximab are effective treatments compared with placebo for RA patients who are not well controlled by conventional DMARDs, improving control of symptoms, improving physical function, and slowing radiographic changes in joints. The combination of a TNF inhibitor with methotrexate was more effective than methotrexate alone in early RA, although the clinical relevance of this additional benefit is yet to be established, particularly in view of the well-established effectiveness of MTX alone. An increased risk of serious infection cannot be ruled out for the combination of methotrexate with adalimumab or infliximab. The results of the economic evaluation based on BRAM are consistent with the observations from the review of clinical effectiveness, including the ranking of treatments. TNF inhibitors are most cost-effective when used as last active therapy. In this analysis, other things being equal, etanercept may be the TNF inhibitor of choice, although this may also depend on patient preference as to route of administration. The next most cost-effective use of TNF inhibitors is third line, as recommended in the 2002 NICE guidance. Direct comparative RCTs of TNF inhibitors against each other and against other DMARDs, and sequential use in patients who have failed a previous TNF inhibitor, are needed. Longer term studies of the quality of life in patients with RA and the impact of DMARDs on this are needed, as are longer studies that directly assess effects on joint replacement, other morbidity and mortality.

Adalimumab↗
PubMed2004

Percutaneous radiofrequency ablation of pulmonary metastases in patients with colorectal cancer.

INTRODUCTION: This study aimed to assess the safety and efficacy of imaging-guided percutaneous radiofrequency ablation (RFA) for local control of lung metastases from colorectal cancer (CRC). METHODS: Twenty patients with lung metastases from CRC were treated with a RITA Starburst XL electrode and RITA 1500 generator using temperature control and impedance monitoring. Patients received intravenous sedation and analgesia, or local anaesthetic, and stayed in hospital for at least 24 h after treatment. RFA was assessed with computed tomography (CT) at 1 week and 1 month, and then every 3 months. RESULTS: Forty-four CRC lung metastases in 19 patients were treated successfully at 25 treatment sessions. Five of 19 patients were retreated for new lesions. There were 13 pneumothoraces following the 25 treatments, and six patients required drainage. The median length of follow-up was 730 (range 148-924) days. Six months after treatment CT demonstrated that three lesions had progressed, 25 metastases were stable or smaller, and 11 were no longer visible. At 12 months five metastases had progressed, 11 were smaller or stable, and nine were not visible. CONCLUSION: Percutaneous imaging-guided RFA was associated with modest morbidity. RFA can achieve local control of CRC lung metastases: nine of 25 metastases were not visible on CT at 12 months after treatment.

Adult↗
PubMed2004

Intestinal permeability in patients with irritable bowel syndrome after a waterborne outbreak of acute gastroenteritis in Walkerton, Ontario.

BACKGROUND: Post-infectious irritable bowel syndrome is a common clinical phenomenon of uncertain aetiology. AIM: To test the association between intestinal permeability and irritable bowel syndrome symptoms 2 years after a large waterborne outbreak of bacterial gastroenteritis. METHODS: Consecutive adults with Rome I irritable bowel syndrome and controls without irritable bowel syndrome attending a community clinic were enrolled. Intestinal permeability was measured as the ratio of fractional urinary excretions of lactulose and mannitol, and compared among cases vs. controls and predictors of abnormal intestinal permeability were assessed. RESULTS: A total of 218 subjects (132 irritable bowel syndrome cases and 86 non-irritable bowel syndrome controls) completed the study protocol. About 27 (12%) had been diagnosed with the irritable bowel syndrome before the outbreak and 115 (53%) had been ill during the outbreak. Lactulose-mannitol ratios were increased among cases vs. controls (Mann-Whitney mean rank 118.8 vs. 95.3, P = 0.007), and cases were more likely to have a ratio >0.020 (P = 0.007). Among cases, those with increased intestinal permeability were more likely to report increased stool frequency. Both irritable bowel syndrome symptoms and male gender, but not diarrhoeal illness during the outbreak, were significant predictors of abnormal permeability. CONCLUSIONS: Irritable bowel syndrome symptoms are associated with a subtle increase in intestinal permeability irrespective of prior gastroenteritis. This may improve understanding of the aetiology of both sporadic and post-infectious irritable bowel syndrome.

Acute Disease↗
PubMed2004

The clinical and cost-effectiveness of anakinra for the treatment of rheumatoid arthritis in adults: a systematic review and economic analysis.

OBJECTIVES: To review the evidence of the clinical and cost-effectiveness of anakinra, an interleukin-1 receptor antagonist (IL-1Ra), for the treatment of rheumatoid arthritis (RA) in adults. DATA SOURCES: Electronic bibliographic databases. Scrip, Food and Drug Administration (FDA) submissions for new drug applications, European Agency for the Evaluation of Medicinal Products (EMEA) reports and the pharmaceutical company submission to the National Institute for Clinical Excellence. REVIEW METHODS: Studies were identified that included randomised controlled trials (RCTs) or economic evaluations of anakinra in adult patients with RA. Existing health economic reviews were also assessed. Data were extracted and quality assessed using a structured approach. The Birmingham Rheumatoid Arthritis Model (BRAM) was used to compare disease-modifying antirheumatic drug (DMARD) sequences, chosen to reflect current clinical practice, with and without anakinra, at different points in the DMARD sequence. RESULTS: Five high-quality RCTs of anakinra in adult patients with RA, involving a total of 2905 patients, of whom 2146 received anakinra, were identified. The results of the clinical trials were consistent with clinical benefit (compared with placebo) as measured by American College of Rheumatology (ACR) composite response rate at 6 months. Variation in response rate was seen across the trials, which is likely to be a reflection of the size of the trials and the wide range of doses evaluated. Consistent benefit was seen at the higher dose evaluated. Benefit was evident both with monotherapy and when used in combination with methotrexate. Data on the efficacy end-points evaluated in a large pragmatic safety study have not been made available, which is of concern. Anakinra treatment was associated with a high incidence of injection-site reactions. Serious adverse events were infrequent, but longer term follow-up is required. No fully published economic evaluations of anakinra in patients with RA were identified. The BRAM gives a base-case estimate of the incremental cost-effectiveness ratio (ICER) of anakinra of 106,000 pounds to 604,000 pounds/quality-adjusted life-year (QALY). In the sensitivity analyses substantial variations were made in key parameters and ICERs were shown to be responsive. However, ICERs did not drop below 50,000 pounds/QALY in any univariate sensitivity analysis. CONCLUSIONS: Anakinra can be considered modestly effective in the treatment of RA based on ACR response, although no conclusion can currently be made on the effect of treatment on disease progression. Adjusted indirect comparison suggests that anakinra may be significantly less effective at relieving the clinical signs and symptoms of RA, as measured by the ACR response criteria, than tumour necrosis factor (TNF) inhibitors all used in combination with methotrexate, although these results should be interpreted with caution. The BRAM produces an ICER for anakinra substantially higher than those for infliximab and etanercept. However, patients may respond to anakinra when they have not responded to other TNF inhibitors, as these agents have a different mechanism of action. Thus, anakinra may produce a clinically significant and important improvement in some patients that they could not otherwise have achieved. Further research would be valuable in the following areas: RCTs to evaluate the efficacy, safety and cost of anakinra over the longer term; comparative trials of anakinra with other DMARDs and biological modifiers; assessment of the role of anakinra in the treatment of patients who have failed to achieve a benefit while taking infliximab or etanercept; assessment on the impact of DMARDs and anakinra on joint replacement, mortality and quality of life; controlled clinical trials of combination therapy with two anticytokines; investigations into newer biological therapies; and the utility of radiographic outcomes in clinical trials of RA.

Adult↗
PubMed2003

v-Jun stimulates both cdk2 kinase activity and G1/S progression via transcriptional repression of p21 CIP1.

Previous studies have shown that the viral Jun (v-Jun) oncoprotein induces marked alterations in cell cycle control, which are associated with, and may be caused by, increased cdk2 kinase activity. Since p21 CIP1 is an important regulator of cdk2, we investigated whether aberrant expression of this cyclin-dependent kinase inhibitor might contribute to cell cycle deregulation by v-Jun. We find that the basal levels of p21 CIP1 mRNA and protein expression are greatly reduced in chick embryo fibroblasts (CEF) transformed by v-Jun, and that v-Jun blocks the increases in p21 CIP1 expression that normally accompany growth inhibition induced by serum deprivation or confluency in untransformed CEF. Importantly, ectopic expression of p21 CIP1 in v-Jun-transformed CEF inhibits both cdk2 kinase activity and cell cycle progression, indicating that these alterations in p21 CIP1 expression are likely to be functionally significant for growth deregulation. We also investigated the mechanism through which v-Jun disturbs p21 CIP1 expression and the possible involvement of a known p21 CIP1 regulator, p53, as an intermediate in this process. This analysis revealed that repression is mediated primarily at the level of p21 CIP1 gene transcription, however the mechanism is complex; both p53-dependent and -independent mechanisms contribute as judged by analysis of p21 CIP1 promoter mutants and other assays of p53 transcriptional activity.

Amino Acid Sequence↗
PubMed2001

Transient hyperinsulinism in an asphyxiated newborn infant with hypoglycemia.

We describe a case of transient hyperinsulinism in an asphyxiated newborn infant with hypoglycemia. Although hypoglycemia in birth asphyxiated infants is generally attributed to depletion of glycogen stores, we observed severe hyperinsulinism associated with the hypoglycemia. The hypoglycemia was refractory to high glucose delivery rates (25 mg/kg/min), but responded to a combination of octreotide and diazoxide. At 3 weeks of age, the medications were discontinued and infant was normoglycemic on glucose infusion rates of 5-8 mg/kg/min. Subsequent insulin studies were within normal limits. Transient hyperinsulinism should be considered in asphyxiated infants with protracted hypoglycemia and medications designed to suppress insulin secretion may be useful in refractory cases.

Asphyxia Neonatorum↗
PubMed2001

Outcome of stroke patients without angiographically revealed arterial occlusion within four hours of symptom onset.

BACKGROUND AND PURPOSE: Follow-up imaging data from stroke patients without angiographically apparent arterial occlusions at symptom onset are lacking. We reviewed our Emergency Management of Stroke (EMS) trial experience to determine the clinical and imaging outcomes of patients with ischemic stroke who showed no arterial occlusion on angiograms obtained within 4 hours of symptom onset. METHODS: All patients in this report were participants in the EMS trial that was designed to address the safety and potential efficacy of combined IV and intraarterial thrombolytic therapy with recombinant tissue plasminogen activator (rt-PA) in patients with acute ischemic stroke. RESULTS: Thirty-five patients were randomized to receive either IV rt-PA (n = 17) or placebo (n = 18), followed by cerebral angiography. No symptomatic arterial occlusion was evident in 10 (29%) of the 34 patients. Eight (80%) of 10 patients without angiographically apparent clot within 4 hours of symptom onset had a new cerebral infarction confirmed on follow-up brain imaging. The median 72-hour infarction volume was 2.4 cc (range, 1-30 cc). Four of the 10 "no-clot" patients had a favorable 3-month outcome as assessed by Barthel Index (score, 95 or 100) and modified Rankin Scale (score, 0 or 1). The six remaining patients had 3-month Rankin Scale scores of 1 (Barthel of 90), 2, 3, 4, or 5. CONCLUSION: Acute ischemic stroke patients with a neurologic deficit but a negative angiogram during the first 4 hours after symptom onset usually develop image-documented cerebral infarction, and approximately half suffer from long-term functional disability. The two most likely explanations for negative angiograms are very early irreversible ischemic damage despite recanalization or ongoing ischemia secondary to clot in non-visible penetrating arterioles or in the microvasculature.

Aged↗
PubMed2001

Systematic review of randomised controlled trials of sildenafil (Viagra) in the treatment of male erectile dysfunction.

BACKGROUND: Sildenafil (Viagra), a new oral drug for the treatment of erectile dysfunction, was licensed for use across Europe in 1998. AIM: To examine the effectiveness and safety of sildenafil as an oral treatment for erectile dysfunction. DESIGN OF STUDY: Systematic review and meta-analysis. SETTING: All published or unpublished randomised controlled trials comparing sildenafil with a placebo or alternative therapies. METHOD: Published studies were sought by computerised searches of electronic databases using the keywords 'sildenafil' and 'Viagra'. A hand search was also done of the British Medical Journal, Lancet, Journal of the American Medical Association, New England Journal of Medicine, British journal of General Practice, Drug, Inpharma and Scrip. An assessment of quality of all identified studies and data extraction was undertaken independently by two researchers. Results were combined in a meta-analysis where appropriate, using RevMan version 3. RESULTS: Twenty-one trials were identified. All trials showed a statistically significant improvement in erectile or sexual function in patients using sildenafil compared with a placebo. A meta-analysis of 16 trials reporting a global efficacy response showed that men were 3.57 (95% CI = 2.93-4.43) times as likely to have improved erections on sildenafil compared with those on a placebo. The number needed to treat to have one man with improved erections was two. The drug has a relatively safe side-effect profile. CONCLUSIONS: Available research shows that sildenafil is an effective treatment for male erectile dysfunction. Many trial participants had some baseline erectile function and it is probable that in clinical practice, where the erectile function tends to be more impaired, the number needed to treat may be higher.

Adult↗
PubMed2001

Uremic toxicity: present state of the art.

The uremic syndrome is a complex mixture of organ dysfunctions, which is attributed to the retention of a myriad of compounds that under normal condition are excreted by the healthy kidneys (uremic toxins). In the area of identification and characterization of uremic toxins and in the knowledge of their pathophysiologic importance, major steps forward have been made during recent years. The present article is a review of several of these steps, especially in the area of information about the compounds that could play a role in the development of cardiovascular complications. It is written by those members of the Uremic Toxins Group, which has been created by the European Society for Artificial Organs (ESAO). Each of the 16 authors has written a state of the art in his/her major area of interest.

Cardiovascular Diseases↗
PubMed2001

An update of neuroprotectants in clinical development for acute stroke.

Neuroprotectants are drugs designed to treat stroke by preserving ischemic neurons in the penumbra. Despite numerous studies over the past ten years, no such drug has yet shown clinical efficacy. This article reviews those trials completed since 1999, including assessments of drugs that modify receptors or ion flow, block leukocyte adhesion receptors or stabilize membranes. In addition, ongoing trials and early trials using novel mechanisms of action, such as hypothermia and antioxidants, are discussed.

Acute Disease↗
PubMed2000

Preincubation with endothelial cell monolayers increases gene transfer efficiency into human bone marrow CD34(+)CD38(-) progenitor cells.

Retroviral gene transfer studies targeting bone marrow CD34(+)CD38(-) stem cells have been disappointing because of the rarity of these cells, their G(0) cell cycle status, and their low or absent expression of surface retroviral receptors. In this study, we examined whether preincubation of bone marrow CD34(+)CD38(-) stem cells with a hematopoietically supportive porcine microvascular endothelial cell line (PMVECs) could impact the cell cycle status and expression of retroviral receptors in pluripotent CD34+CD38- cells and the efficiency of gene transfer into these primitive target cells. PMVEC coculture supplemented with GM-CSF + IL-3 + IL-6 + SCF + Flt-3 ligand induced >93% of the CD34(+)CD38(-) population to enter the G(1) or G(2)/S/M phase while increasing this population from 1.4% on day 0 to 6.5% of the total population by day 5. Liquid cultures supplemented with the identical cytokines induced 73% of the CD34(+)CD38(-) population into cell cycle but did not maintain cells with the CD34(+)CD38(-) phenotype over time. We found no significant increase in the levels of AmphoR or GaLVR mRNA in PMVEC-expanded CD34(+)CD38(-) cells after coculture. Despite this, the efficiency of gene transfer using either amphotropic vector (PA317) or GaLV vector (PG13) was significantly greater in PMVEC-expanded CD34(+)CD38(-) cells (11.4 +/- 5.6 and 10.9 +/- 5.2%, respectively) than in either steady state bone marrow CD34(+)CD38(-) cells (0.6 +/- 1.7 and 0.2 +/- 0.6%, respectively; p < 0.01 and p < 0.01) or liquid culture-expanded CD34(+)CD38(-) cells (1.4 +/- 3.5 and 0.0%, respectively; p < 0.01 and p < 0.01). Since PMVEC coculture induces a high level of cell cycling in human bone marrow CD34(+)CD38(-) cells and expands hematopoietic cells capable of in vivo repopulation, this system offers potential advantages for application in clinical gene therapy protocols.

ADP-ribosyl Cyclase↗
PubMed2000

v-Jun sensitizes cells to apoptosis by a mechanism involving mitochondrial cytochrome C release.

v-Jun shares the ability of the Myc, E1A, and E2F oncogenes to both sustain cell cycle progression and promote apoptosis in the absence of mitogenic stimulation. To gain an insight into the mechanism of apoptosis sensitization, we examined the possible involvement of key regulatory proteins previously implicated in oncogene-induced cell death during v-Jun-induced apoptosis triggered by serum withdrawal. We observed that ectopic expression of the anti-apoptotic Bcl-2 protein, or of two downstream effectors of growth factor signalling, v-PI 3-Kinase and v-Src, partially or completely suppressed apoptosis. Apoptosis was also observed in the presence of serum growth factors when endogenous PI3K activity was blocked using the synthetic inhibitor LY294002, further suggesting an important role for PI3-K in cell survival. Cytochrome C was released into the cytosol of apoptotic v-Jun expressing cells, and this release was inhibited by Bcl-2, suggesting an important role for mitochondrial dysfunction in v-Jun induced apoptosis. In contrast, inhibition of Fas signalling using dominant negative FADD did not inhibit apoptosis, nor was there any evidence for accumulation or activation of p53 in v-Jun transformed cells. Consistent with this latter observation, inhibition of p53 function by HPV16 E6 protein had no effect on v-Jun induced cell death. Taken together, these results suggest that mitochondrial dysfunction is an important component of the mechanism through which v-Jun sensitizes cells to apoptosis, but that the apoptotic signals elicited by v-Jun upstream of the mitochondria do not depend on increased levels of p53 activity or Fas signalling.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Transient deactivation of ERK signalling is sufficient for stable entry into G0 in primary avian fibroblasts.

Re-entry into the cell cycle from quiescence requires the activation of mitogen-activated protein (MAP) kinases of the extracellular-signal-regulated kinase (ERK) family [1,2]. The relationship between ERK and cell-cycle control is, however, complex, as ERK activation can also lead to terminal differentiation [3] or a senescence-like growth arrest [4]. Here, we report that reversible cell-cycle exit induced by serum withdrawal in primary avian fibroblasts is associated with rapid deactivation of ERK, but ERK activity is subsequently regenerated and sustained at high levels in fully quiescent (G0) cells. As in proliferating cells, ERK activation during G0 required the MAPkinase kinase MEK and was partially dependent on cell adhesion. Active, phosphorylated ERK was concentrated in the nucleus in cycling cells, but was largely confined to the cytoplasm during G0. This was unexpected, as activatory phosphorylation mediated by MEK is thought to play an important role in promoting nuclear translocation [5,6]. These results indicate that transient deactivation of ERK signalling can be sufficient for stable cell-cycle exit, and that MEK-mediated phosphorylation is not sufficient for nuclear translocation of active ERK in G0. Cytoplasmic sequestration may prevent active ERK from accessing critical nuclear cell-cycle targets, thus allowing quiescent or post-mitotic cells to retain ERK activity for other physiological functions.

3T3 Cells↗