We have evaluated a commercial assay for serum IgA class antibodies to tissue transglutaminase, the enzyme identified as the major endomysial autoantigen in coeliac disease (CD). Sera were available from 130 adults diagnosed with CD in Southern Derbyshire between 01 01 97 and 31 12 99. Sera from 100 patients without villous atrophy on small intestinal biopsy were controls. The ability of the assay to detect abnormally low total IgA levels was assessed using sera from 18 subjects with IgA deficiency. Sensitivity and specificity of this IgA-anti tissue transglutaminase (tTGA) assay (86.2%, 91.0%) were inferior to endomysial antibody (EMA; 93.8%, 100%). tTGA has significantly higher sensitivity than IgA-antigliadin (76.2%). tTGA was appropriately undetectable (<0.03 U/mL) in 17 of 18 subjects with selective IgA deficiency. The high likelihood ratio (35) for tTGA at levels >9.0 U/mL and methodological advantages over EMA suggest that tTGA could be used as a first line diagnostic test for CD. At tTGA levels of 4-9 U/mL, use of EMA as a second line test would improve specificity.
A survey of hospital laboratory services has demonstrated marked deficiencies in the performance of gastrointestinal function tests. The repertoire of gastrointestinal investigations available varies widely between laboratories and, in general, analyses are performed infrequently. Most laboratories do not perform internal quality control, and inter-laboratory reproducibility of some analytes is very poor. A wide variety of protocols and reference ranges are in use, many of which are unevaluated. Some analytical methods and protocols in current use are outdated, with published improvements not being applied.
The 1-hour serum xylose (surface area corrected) as an indication of xylose absorption after 5 g oral D-xylose has been compared with the 5-hour urine excretion test in a tropical population. The study confirmed that the peak serum xylose concentration occurs at 1 hour and that correction to a constant body surface are improves the discrimination between subjects with normal and impaired xylose absorption. The significantly lower reference range for the 1-hour surface area corrected serum xylose (0.55-1.11 mmol/l) compared to the UK figure reflects the reduced absorptive capacity of the jejunum, a result of tropical enteropathy. In view of the difficulties in obtaining accurate urine collections in tropical countries, especially in field studies, it is recommended that the 1-hour serum xylose (surface area corrected) should be adopted as the standard test of xylose absorption.
Abstract: In the British Isles the majority of volcanic rocks containing upper mantle and lower crustal xenoliths occur in Scotland. Most of the occurrences are of Carboniferous–Permian age. This paper presents new data on the mineral chemistry of spinel lherzolite xenoliths from the five principal Scottish tectonic terranes. Compositional variations among the minerals emphasize the broad lateral heterogeneity of the subcontinental lithospheric mantle across the region. The remarkable range of Al 2 O 3 v. CaO exhibited by the clinopyroxenes compared with data from other ‘xenolith provinces' emphasizes the extremely complex tectonomagmatic history of the Scottish lithosphere. The generalized age increase from southern and central Scotland to the Northern Highland and Hebridean terranes of the north and NW, with concomitant complexity of geological history, is reflected also by trace element and isotopic studies. Reaction relationships in lherzolites from the Hebridean Terrane, owing to pervasive metasomatism, involve secondary growth of sodic feldspar. This, and light REE enrichment of clinopyroxenes, points to involvement of a natro-carbonatitic melt. Most pyroxenitic xenoliths are inferred to form a basal crustal layer with a generally sharp discontinuity above the underlying (dominantly lherzolitic) mantle. A second discontinuity is inferred to separate these ultramafic cumulates from overlying, broadly cognate metagabbroic cumulates.
We have improved the enzyme-linked immunosorbent assay for IgA-class antibodies to gliadin in serum by evaluating earlier publications. We also assess the value of measuring these antibodies when screening for adult celiac disease and monitoring dietary compliance. Of 61 adults with untreated celiac disease, 57 had abnormal results, giving a sensitivity for the test of 0.93. Patients (n = 283) attending a gastroenterology clinic formed the control group. The predictive values of positive results and negative results were 50% and 99.7%, respectively, indicating that the test has a role in helping select those subjects in whom small bowel biopsy is indicated. Adults with celiac disease, after two years on a strict gluten-free diet, and normal subjects showed no significant difference in serum IgA-class anti-gliadin antibody concentrations. The test thus provides objective evidence of dietary compliance in addition to its role as a screening test.
Editor—Agreus and Talley’s recommendations for the use of Helicobacter pylori testing in the management of patients with newly appeared dyspepsia1 differ from published guidelines.2,3 They consider eradication therapy an acceptable alternative to endoscopy for patients with a positive test result when access to this investigation is difficult. This alternative option is probably a fait accompli in primary care.
In June 1995 I sent a questionnaire to all 298 general practitioners in north and east Devon asking how they would use H pylori testing for the management of patients with dyspepsia. After a reminder questionnaire, 271 general practitioners (91%) responded. The table shows the results.
Only 73 (27%) said they would limit the use of this test to younger patients (under 50 years of age) as recommended by published guidelines at the time.2 Eighty five did not know when to use the test but many of these said how they would manage patients with a positive result. Most general practitioners (73%) would use eradication therapy rather than endoscopy in younger patients with a positive test result. Seventy eight (29%) said they would also attempt eradication therapy in older patients.
At the time of the survey patients referred for endoscopy had to be placed on a waiting list. General practitioners might have preferred to prescribe antibiotics for dyspeptic patients with a positive H pylori result, which is likely to cure a possible peptic ulcer, rather than wait too long for the diagnosis to be confirmed by endoscopy.
I thank all general practitioners in north and east Devon district for their cooperation and Dr I Morrel for his help in designing the questionnaire.
AIMS: To study the incidence and possible cause of abnormalities of the subfoveal choriocapillaris after surgical excision of subfoveal choroidal neovascularisation in age-related macular degeneration (ARMD). METHODS: The postoperative fluorescein angiograms and colour photographs of 29 eyes of 29 patients were reviewed after surgical excision of subfoveal choroidal neovascularisation in exudative ARMD. Preoperative and postoperative fluorescein angiograms were examined for perfusion of the subfoveal choriocapillaris. The excised subfoveal choroidal neovascular membranes from eight eyes that demonstrated postoperative abnormalities of the choriocapillaris were embedded in paraffin, serially sectioned and examined for the presence of the choriocapillaris. RESULTS: Postoperative fluorescein angiograms revealed abnormal perfusion of the subfoveal choriocapillaris in 26 of the 29 eyes (90%) and in all eight eyes that had histopathological examination of the surgical specimens. Examination of serial sections demonstrated that none of the excised neovascular membranes contained choriocapillaris. CONCLUSIONS: Abnormal perfusion of the subfoveal choriocapillaris was frequently present following removal of the subfoveal neovascular membrane in ARMD. The histopathological study demonstrated that abnormalities of the choriocapillaris were not due to removal of the choriocapillaris at the time of surgery.
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