Functional diversity of nematode communities in the southwestern North Sea.

A range of biological traits of nematode species were combined to identify patterns in the functional composition of their assemblages collected at 19 soft-bottom stations in the southwestern North Sea with the primary aim to determine which environmental variables control communities. We used 19 categories of five biological traits thought or known to represent an important ecological function. These were related to buccal morphology, tail shape, body size, body shape and life history strategy. Data on trait membership was provided by biological information on species and genera. A total of 79 different trait combinations were recorded. Results from correlation analyses revealed several significant relationships between traits. Some trait combinations were shared by different species and genera, and the ratio of realised versus total number of possible trait combinations of < 1 suggested that some trait combinations were not represented by the nematode fauna from this region. The functional composition of nematodes was strongly linked to median particle diameter and silt content of the sediment and water depth. The approach adopted and our attempts at defining and analysing functional attributes of nematode communities raised a number of conceptual and methodological issues which are discussed.

Delays by patients in seeking treatment for acute chest pain: implications for achieving earlier thrombolysis.

A study was set up to identify why patients delay seeking medical assistance after myocardial infarction. The study was performed in 100 consecutive patients with suspected acute myocardial infarction admitted to either the University Hospital of Wales, Cardiff, UK, or the Royal Jubilee Hospital, Victoria, British Columbia, Canada (50 patients from each centre). The main outcome measure was the delay from the onset of symptoms to admission to hospital. The mean total delay before admission was 385 minutes (SEM 45). The mean delay incurred by the patient in seeking assistance was 172 minutes (SEM 27), representing 45% of the total. Delay was longer in patients with crescendo angina and shorter in those later confirmed to have myocardial infarction. Patients with prior ischaemic heart disease (74% of patients) presented later than those with no such history. No other demographic or clinical factors predicted early or late presentation. Delays in seeking medical assistance after the onset of severe chest pain contribute significantly to total delays in patients' hospital admission and thrombolysis. The unexpected observation that patients with known ischaemic heart disease delay longer before seeking help in spite of their frequent contact with doctors, suggests that opportunities for educating patients are being wasted. Major efforts are needed to understand and modify behaviour of patients with chest pain to further reduce delays in treatment.

T-cell epitopes recognized within the 65,000 MW hsp in patients with IgA nephropathy.

IgA nephropathy (IgAN) is the commonest cause of glomerulonephritis and clinical exacerbation of IgAN is frequently associated with mucosal infection. T-cell receptor gamma delta (TCR gamma delta+) cells are increased in both the circulation and in renal biopsies of patients with progressive IgAN. We examined the hypothesis that specific peptides within the 65,000 MW heat-shock protein (hsp) might stimulate TCR gamma delta cells and play a part in the immunopathogenesis of IgAN. We studied T-cell proliferative responses stimulated by overlapping peptides derived from the sequence of mycobacterial 65,000 MW hsp. Three T-cell epitopes have been identified (peptides 51-65, 71-85 and 281-295). The three peptides have a synergistic effect and they stimulate significantly higher proliferation of T cells in patients with IgAN than in disease or healthy controls. This response was inhibited by monoclonal antibodies (mAb) to TCR gamma delta+ and human leucocyte antigen (HLA) class I, but not by mAb to HLA class II. The involvement of TCR gamma delta+ cells was confirmed by up-regulation of the proportion of TCR gamma delta+ cells when stimulated with the three specific peptides. We suggest that IgAN might be associated with mucosal infection by a variety of micro-organisms and that peptides within the microbial hsp cross-react with the homologous human hsp which may stimulate TCR gamma delta+ cells and play a part in the pathogenesis of IgAN.

Impaired outcome of continuous ambulatory peritoneal dialysis in immunosuppressed patients.

BACKGROUND: Although immunodeficiency predisposes to CAPD peritonitis with fungal or unusual organisms, the role of immunosuppression as a predisposing factor for CAPD peritonitis, as well as the outcome of such episodes, remains uncertain. METHODS: The incidence, spectrum of infectious organisms, and outcome of CAPD peritonitis was retrospectively reviewed in 39 immunosuppressed and 146 non-immunosuppressed patients treated with CAPD over the calendar year 1993. RESULTS: Immunosuppressed patients were younger (mean 44 vs 57 years, P<0.001) and had an increased incidence of previous transplantation, glomerulonephritis, systemic lupus erythematosus, and vasculitis. Immunosuppressed patients had more episodes of peritonitis (69/29 patients vs 99/147, P<0.001), required more frequent hospital admission (25/39 vs 33/146, P<0.001), had more days off CAPD (331 vs 242, P<0.001), and required more laparotomies to remove infected CAPD catheters (11/39 vs 14/146, P<0. 01). Immunosuppression was associated with increased infection due to S.aureus and fungi, which may have contributed towards increased morbidity in this group. Current immunosuppression or a recent history of immunosuppression appeared to be equally potent risk factors for infection. There was a trend for the incidence of infection to parallel the aggressiveness of immunosuppression. CONCLUSIONS: Immunosuppression is an important risk factor for CAPD peritonitis. A high index of suspicion for infection and aggressive chemotherapy are mandatory. CAPD may not be the initial therapy of choice in this high-risk group.

Role of gamma delta T cells in pathogenesis and diagnosis of Behcet's disease.

BACKGROUND: Behcet's disease (BD) is a multisystem disorder of unknown pathogenesis. The diagnosis is based on a set of international clinical criteria. Previous investigations have suggested that immunological cross-reactivity between peptides within streptococcal heat-shock proteins and human peptides might be involved in the pathogenesis of BD. We tested four peptides from mycobacterial heat-shock proteins to see if they specifically stimulated gamma delta T cells from BD patients. We then investigated this response to see whether it could be used as a laboratory test to diagnose BD. METHODS: We used a T-cell proliferative test to assay responses to four mycobacterial 65 kDa heat-shock-protein peptides and to four homologous peptides derived from the sequence of the human 60 kDa heat-shock protein. FINDINGS: We elicited significant gamma delta T-cell responses to the mycobacterial peptides in 25 (76%) of 33 patients with BD, compared with 2 (3.6%) of 55 controls with recurrent oral ulcers, systemic disease, or no disorders. The proportion of BD patients who had false-negative results decreased if the test was done during clinical manifestation of disease activity. There was a correlation between disease activity and T-cell responses. Four homologous peptides from human 60 kDa heat-shock protein also specifically stimulated T cells from patients with BD but with lower stimulation indices. INTERPRETATION: Activation of peripheral-blood mononuclear cells with the four heat-shock-protein peptides elicited significant T-cell proliferative responses by the gamma delta subset of T cells, which may regulate alpha beta T cells. Because these peptides have a high specificity for BD, this assay can be used as a laboratory diagnostic test for BD.