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Biomedical subjects

P A Bacon

Publications and source records attributed to P A Bacon.

At least 19 recordsLinked to original sources
PubMed1999

Localized bowel vasculitis: postoperative cyclophosphamide or not?

We describe 2 patients with necrotizing vasculitis localized to the bowel, who were treated by excision of the involved tissue. Postoperatively, there was no evidence of active vasculitis, and both patients remain in remission on followup, without the use of immunosuppressive treatment. Evidence that an abnormal local microenvironment is necessary to sustain chronic inflammation may explain why surgical excision can be an important tool in the treatment of vasculitis.

Adult↗
PubMed1998

Examination of disease severity in systemic vasculitis from the novel perspective of damage using the vasculitis damage index (VDI).

Assessment of disease severity in systemic vasculitis encompasses mortality, which is now uncommon, and morbidity, which is increasing in significance. Morbidity includes permanent scars or damage, an evolving concept offering a novel perspective which may be particularly valuable in chronic disease. We have developed a method for assessing damage in systemic vasculitis, but the relationship between damage and disease severity was unknown. Therefore, we examined whether the number of items of damage or the pattern of damage varied with the severity of systemic vasculitis. We established the characteristics of severe disease by examining fatal vasculitis as an example of the most severe disease possible. We then showed that more damage occurred in fatal vasculitis, more systems were damaged, and critical damage akin to organ failure was more common in fatal than non-fatal vasculitis. These observations were reproduced in specific diagnostic groups, namely classical Wegener's granulomatosis and systemic rheumatoid vasculitis. Thus, severe disease was characterized by many items of damage, multisystem damage and critical damage. This pattern of damage was also seen in a subgroup of patients with non-fatal vasculitis, who also have severe disease.

Adult↗
PubMed1997

Inhibition of T cell apoptosis in the rheumatoid synovium.

Synovial T cells in rheumatoid arthritis are highly differentiated and express a phenotype suggesting susceptibility to apoptosis (CD45RB dull, CD45RO bright, Bcl-2 low, Bax high, Fas high). However, no evidence of T cell apoptosis was found in synovial fluid from any of 28 patients studied. In contrast, synovial fluid from 10 patients with crystal arthritis showed substantial levels of T cell apoptosis. The failre of apoptosis was not an intrinsic property of rheumatoid synovial T cells, as they showed rapid spontaneous apoptosis on removal from the joint. Synovial T cells from rheumatoid arthritis and gout patients could be rescued from spontaneous apoptosis in vitro either by IL-2R gamma chain signaling cytokines (which upregulate Bcl-2 and Bcl-XL) or by interaction with synovial fibroblasts (which upregulates Bcl-xL but not Bcl-2). The phenotype of rheumatoid synovial T cells ex vivo (Bcl-2 low, Bcl-xL high) suggested a fibroblast-mediated mechanism in vivo. This was confirmed by in vitro culture of synovial T cells with fibroblasts which maintained the Bcl-xL high Bcl-2 low phenotype. Synovial T cells from gout patients were Bcl-2 low Bcl-xL low and showed clear evidence of apoptosis in vivo. Inhibition experiments suggested that an integrin-ligand interaction incorporating the Arg-Gly-Asp motif is involved in fibroblast-mediated synovial T cell survival. We propose that environmental blockade of cell death resulting from interaction with stromal cells is a major factor in the persistent T cell infiltration of chronically inflamed rheumatoid synovium.

Apoptosis↗
PubMed1997

Development and initial validation of the Vasculitis Damage Index for the standardized clinical assessment of damage in the systemic vasculitides.

OBJECTIVE: To develop and validate the Vasculitis Damage Index (VDI) for the standardized clinical assessment of damage in the systemic vasculitides. METHODS: Using a nominal group consensus approach, the Birmingham Vasculitis Group generated guiding principles for assessment of damage in all systemic vasculitides. Damage was defined as irreversible change resulting from scars. Consensus principles were developed into the VDI, including guidelines for use, a list of items of damage, and a glossary. RESULTS: For 100 surviving patients with systemic vasculitis, the median VDI score at last observation was 3 (range 0-8). Within the Wegener's granulomatosis subgroup, the median VDI score for 12 non-survivors was higher than for 47 survivors (non-survivors median score 7, interquartile range 5-8 versus survivors median score 4, interquartile range 2-5; P = 0.003). VDI scores for 100 patients with systemic vasculitis increased from initial presentation to last observation by a median score of 3 (range 1-4; P < 0.001). The VDI assesses more items and is more sensitive to change than other indices of damage (P < 0.001). Using the VDI, trained observers can produce moderately consistent damage scores. CONCLUSION: The VDI is a sensitive, reproducible, comprehensive, and credible clinical tool for quantifying damage. The data presented herein should enable further validation and testing of the VDI in specific vasculitic syndromes, and should facilitate the comparison of different therapies.

Humans↗
PubMed1997

Disease assessment and management of the vasculitides.

The improvement in survival with chemotherapy has resulted in a change of the natural history of the systemic vasculitic syndromes. The vasculitides are now viewed as chronic disease rather than fatal conditions. Their course is frequently characterized by relapse as well as the scars of irreversible organ damage from disease and drug toxicity. Assessment tools are available which can serve as outcome measures in clinical trials as well as a guide to better management of individual patients. Improvements in therapy in future are dependent on a better understanding of the pathogenesis of these conditions and the ability to assess disease accurately.

Animals↗
PubMed1997

Focal segmental necrotizing glomerulonephritis in rheumatoid arthritis.

We report ten patients with rheumatoid arthritis (RA) who developed a focal segmental necrotizing glomerulonephritis (FSNGN) and extracapillary proliferation typical of vasculitic glomerulonephritis. Five patients also had extrarenal vasculitis. Renal presentation was with renal impairment (n = 9) (median creatinine 726 mumol/l, range 230-1592 mumol/l), microscopic haematuria (n = 8) and proteinuria (n = 10). Nine patients were seropositive for rheumatoid factor and nine had bone erosions. Serum from four of five patients tested by indirect immunofluorescence was positive for antineutrophil cytoplasmic antibody (ANCA) with perinuclear staining. Only three patients had penicillamine or gold therapy. Treatment was with prednisolone and cyclophosphamide (six patients, two of whom were also plasma-exchanged), prednisolone and azathioprine (two patients) and prednisolone alone (two patients). There was a marked improvement in renal function in eight patients. Two patients with dialysis-dependent renal failure recovered renal function, although in one patient this was transient and she required further dialysis 4 months later. Two other patients progressed to dialysis at 3 months and 1 year respectively. Four patients died, one remains dialysis-dependent, and four continue to have good renal function at 5 year follow-up (median creatinine 148.5 mumol/l, range 120-193 mumol/l). One patient was lost to follow-up at 5 years. FSNGN should be considered in all patients with RA and renal impairment, proteinuria and/or microscopic haematuria. This diagnosis appears to be more likely in patients with clinical extrarenal vasculitis, bone erosions or who are seropositive. In these cases, an urgent renal biopsy is indicated.

Adult↗
PubMed1997

Damage occurs early in systemic vasculitis and is an index of outcome.

Because death after acute systemic vasculitis is now uncommon, alternative measures of outcome are required. A significant component of patient morbidity is disease-related damage, which can be quantified by the Vasculitis Damage Index (64 items in 11 organ-based systems). We investigated serially the time-course of damage in 120 patients with systemic vasculitis, to determine the earliest indicators of outcome. High damage scores at 2 years after presentation were characteristic of fatal disease (OR 8.1-12.4). Significant damage occurred within 6 months of presentation, and was a feature of fatal disease. More damage occurred after presentation than after relapse. Lung and multi-system damage were early indicators of poor outcome in severe non-fatal disease. Damage occurs early in systemic vasculitis, and is an indicator of poor outcome. This novel observation, together with evidence of persistent subclinical disease activity and the high frequency of relapse, suggests a need for new treatment strategies. Analogy with the management of acute leukaemia suggests a strategy of early diagnosis and intensive induction of remission, with early escalation of treatment for resistant disease.

Acute Disease↗
PubMed1997

Controlled trial of pulse versus continuous prednisolone and cyclophosphamide in the treatment of systemic vasculitis.

Although cyclophosphamide and prednisolone are effective in treating systemic vasculitis, the optimum treatment regimes and duration of treatment are unknown. We randomized 54 patients aged 15-70 years (median 57.5 years) with systemic vasculitis (classical polyarteritis n = 8, microscopic polyarteritis n = 17, Wegener's granulomatosis n = 29) to treatment with either pulse cyclophosphamide and prednisolone (PCYP) (n = 24) or continuous oral and prednisolone and cyclophosphamide, with the latter followed after a median of 3 months (range 1.5-10 months) by azathioprine (CCAZP) (n = 30). Patients on CCAZP were more likely to develop leucopenia (13/30) than patients on PCYP, (7/24) although the difference was not significant. The numbers of infective episodes during follow up were comparable in the two groups at 1.7/patient for PCYP and 1.66/patient for CCAZP. Overall, 26/30 patients (87%) treated with CCAZP developed treatment-related toxicity, as did 17/24 patients (71%) treated with PCYP. After a median follow-up of 40.4 months (range 0.7-64.8), there was no difference in the frequency of deaths (PCYP 5, CCAZP 4), relapses (PCCYP 7, CCAZP 8), treatment failures (PCYP 4, CCAZP 4), improvement in disease activity scores or renal function. Survival at three years was 77% in patients treated with PCYP, and 90% in patients on CCAZP (p = 0.38). There was a tendency towards increased toxicity in patients treated with the continuous regimen.

Adolescent↗
PubMed1997

Enhanced co-stimulatory ability of synovial fluid accessory cells in rheumatoid arthritis.

We have established in vitro assays that allow the examination of co-stimulatory function of rheumatoid arthritis (RA) antigen-presenting cells (APC). Synovial fluid (SF) and peripheral blood (PB) APC co-stimulatory ability was compared in the activation of peptide-specific human T-cell clones. T-cell receptor (TCR) stimulation by peptide or anti-CD3 antibody allowed the direct comparison of SF and PB APC co-stimulatory activity, separately from their ability to process antigen. SF APC from 15 RA patients consistently enhanced T-cell proliferation when compared to their PB counterparts. Moreover, increasing the numbers of PB APC present resulted in only a minor increase in T-cell proliferation, failing to achieve levels stimulated by SF APC. We propose that the enhanced co-stimulatory function of synovial APC may be a significant factor in the persistence of local immune responses in RA.

Antigen-Presenting Cells↗
PubMed1997

Consistency and validity of patient administered assessment of quality of life by the MOS SF-36; its association with disease activity and damage in patients with systemic lupus erythematosus.

OBJECTIVE: To investigate the metric properties and validity of the assessment of quality of life by the MOS Short Form 36 (SF-36) in patients with systemic lupus erythematosus (SLE) and to examine the effect of disease on quality of life. METHODS: Cross sectional study of 150 patients with SLE (age: mean 39.7 yrs, SD 11.4 yrs; 95% female) attending 2 specialist lupus clinics between November 1994 and April 1995. Shortly before or after the consultation patients completed the SF-36 and the MOS SF-20 with an additional question about fatigue (SF-20+) in random order. Disease activity was measured by the British Isles Lupus Activity Group System (BILAG), disease damage by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage index (SLICC). RESULTS: SF-36 domains were shown to be internally consistent (Cronbach's coefficient alpha > or = 0.71). Significant associations of the SF-36 domains with the corresponding domains of the SF-20+ and with global disease activity measured by BILAG were observed. SF-36 scores in patients with SLE were significantly lower than in controls. Different disease activity levels were significantly associated with different quality of life scores, with excellent ability to record the continuum from good health to serious illness by the SF-36. Disease activity had greater effect on quality of life than age, cumulative damage, or disease duration. CONCLUSION: This study shows the SF-36 is internally consistent and proves construct, discriminatory, and criterion validity for the SF-36 and construct validity for the SF-20+ in patients with SLE. The SF-36 is preferred because of its broader scope of questions, its widespread use, and previous international validation for a wide variety of diseases.

Adult↗
PubMed1996

Undiagnosed systemic lupus erythematosus in the community.

BACKGROUND: Systemic lupus erythematosus (SLE) produces a wide range of symptoms, some of them mild; therefore it may be underdiagnosed. In a pilot study we tested the ability of a screening questionnaire to identify undiagnosed cases in the community. METHODS: A 10-item questionnaire was mailed to 3500 women aged 18-65 randomly selected from a general practice list in Birmingham, UK. A random sample of 300 non-respondents were sent two further mailings. Women returning the questionnaire with three positive answers were to attend for an antinuclear antibody (ANA) test; and those testing positive were to be referred to a rheumatologist for standard clinical assessment. FINDINGS: 1153 (30%) of the women responded, and 307 of these gave three or more positive answers on the questionnaire. The survey disclosed three women with previously undiagnosed SLE; and, in addition, it picked up all four of the women whose SLE had been diagnosed previously. INTERPRETATION: The prevalence of SLE revealed by this survey in Birmingham women is 200/100,000 (95% confidence interval 80 to 412), whereas the prevalence of diagnosed SLE in this age group is 54/100,000 (95% CI 47-62). Thus, a substantial number of undiagnosed cases exist, and further work needs to focus on the prevalence in different ethnic groups and the benefits of early diagnosis and treatment.

Adolescent↗
PubMed1996

Characterization of altered calcium signalling in T lymphocytes from patients with rheumatoid arthritis (RA).

Abnormal function of peripheral blood T lymphocytes is characteristic of RA; diminished proliferation and secretion of cytokines following in vitro mitogen stimulation are observed. We have investigated the calcium flux initiating T cell activation in rheumatoid peripheral blood mononuclear cells (PBMC) to determine whether abnormalities in signalling are also present. We have found that both phytohaemagglutinin (PHA-P)- and anti-CD3-stimulated calcium fluxes were much reduced in the patients' PBMC compared with controls, with a mean six-fold difference (P < 0.01) in rate of Ca2+ flux with PHA-P stimulation. When purified T cells were examined with PHA and CD3 stimulation, a reduction in the peak and plateau [Ca2+]i was observed in RA T cells, but the rate of rise of [Ca2+]i was only reduced in those cells stimulated with PHA. These results suggest that alterations in the initiating signal may underlie the functional T cell abnormalities associated with RA, and that there may be an additional extrinsic influence from non-T cells in the PBMC population.

Arthritis, Rheumatoid↗
PubMed1996

CD4+ CD45RA+ T cells from adults respond to recall antigens after CD28 ligation.

The leukocyte common antigen isoforms CD45RA and CD45RO have long been used to discriminate human naive and memory T cells respectively. This model was largely based on the observation that CD45RO+ T cells respond preferentially to and show a higher frequency of precursors specific for recall antigens. However, CD45RA+ T cells have more stringent requirements for stimulation and standard in vitro assays may favour CD45RO+ cells in this respect. We tested the hypothesis that CD45RA+ T cells respond poorly to in vitro stimulation with recall antigens because of inadequate stimulation rather than a lack of precursors. Limiting dilution analyses (LDA) for tetanus toxoid (TT)-specific T cells were performed in the presence or absence of exogenous anti-CD28 antibody. Addition of anti-CD28 yielded no proliferation in the absence of specific antigen. The precursor frequency for TT in the CD4+ CD45RO+ population was approximately 1:4000, while the frequency of CD4+ CD45RA+ T cells specific for TT was 4- to > 20-fold lower. Addition of anti-CD28 antibody did not significantly alter the apparent precursor frequency for CD45RO+ cells but yielded an enhancement of the value for CD45RA+ cells by 3- to > 5-fold. No enhancement of antigen-specific proliferation by anti-CD28 was observed with CD45RA+ T cells derived from cord blood, although phytohemagglutinin responses of these cells were amplified by CD28 antibody. These results indicate that conventional LDA underestimate the true precursor frequency of antigen-specific cells within the adult CD45RA+ population and support the possibility that a small number of cells revert from a primed (CD45RO+) to an unprimed (CD45RA+) state. The majority of memory T cells, however, appear to reside in the CD45RO+ population.

Adult↗
PubMed1996

Active systemic lupus erythematosus is associated with the recruitment of naive/resting T cells.

The aim of this study was to determine whether active systemic lupus erythematosus (SLE) is associated with recruitment of resting CD45RA+ T cells or reactivation of CD45RO+ memory T cells. Three-colour immunofluorescence was used to determine CD45 isoform expression by CD4+ T cells from 28 patients with SLE. Newly recruited and highly differentiated primed T cells were distinguished by their CD45RB expression. The pattern of CD45 isoform expression varied directly with time since the onset of symptoms in patients with active SLE. Shortly after symptoms appeared, most cells were CD45RA+ resting cells or CD45RO(dull)RB(bright) early primed cells. However, over the course of active disease, patients accumulated CD45RO(bright)RB(dull) cells which represent an advanced state of differentiation. The switch from an early to late primed phenotype correlated significantly with time since the onset of symptoms. The recruitment of resting T cells in active SLE, rather than the simple reactivation of existing memory clones, has implications for understanding the pathology of this disease and for treating it.

Biomarkers↗
PubMed1996

Clinical disease activity in systemic vasculitis.

Long-term follow-up data indicate that the systemic vasculitides are chronic relapsing diseases with high morbidity. It is therefore of paramount importance to distinguish activity, which requires cytotoxic or immunosuppressive therapy, from damage requiring rehabilitation. Damage due to underlying disease or treatment highlights the need for more effective, less toxic treatment regimens. An integrated package for clinically based assessment of disease activity in systemic vasculitis, the Vasculitis Integrated Assessment Log, has been accepted for further evaluation and implementation by the European Community Study Group for use in therapeutic trials. The added value of serologic tests and inflammatory markers in clinical assessment is becoming more clear, and unsuspected disease activity has been revealed by biopsy and imaging of standard sites or affected areas. Integration of these data should enable characterization of high- and low-risk patient subgroups to determine specific therapies.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1995

Marked conservation of complementarity-determining region 3 of the beta-chain of TCRs recognizing a mycobacterial heat shock protein 60-derived peptide with strong sequence similarity to human heat shock protein 60.

The variable gene usage and sequence of human TCRs specific for a particular MHC/peptide combination have been investigated. The peptide comprises amino acids 456-466 of the 65-kDa Mycobacterium tuberculosis heat shock protein (hsp60), and is recognized in the context of HLA-DP. TCRs from both synovial fluid and peripheral blood (PB)-derived T cell clones used only five different V beta genes, three of which are closely related (V beta 6.7a, V beta 6.7b, and V beta 21.3). Among TCRs using these three genes there was marked conservation of the beta-chain sequence, whereby complementarity-determining region 3 (CDR3) contained an amino acid motif (*R*G*, amino acids 96-100) in association with either J beta 1.4 or J beta 2.5. These conclusions were strengthened by analysis of peptide-stimulated T cell lines that revealed not only TCR beta-chain sequences identical with those seen in T cell clones, but also additional beta-chains with similar CDR3 region sequences and J gene usage. In contrast, T cell lines derived by using IL-2 or a control peptide revealed variable usage of V beta and J beta genes; V beta 6.7a/b sequences from these lines and from freshly isolated PB did not contain the CDR3 motif noted in TCRs from Ag-specific T cells. We suggest that the remarkably limited diversity of TCRs noted in this study is a consequence of the similarity between the mycobacterial hsp60 peptide and the equivalent peptide from human hsp60, and reflects the trimming of the TCR repertoire required to maintain self-tolerance.

Amino Acid Sequence↗