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Summary A method is described for the quantitative estimation of clinically important monosaccharides in plasma or whole blood by direct densitometry of chromatographically-separated zones on silica gel layers. Simple modifications of technique originally introduced to improve the reproducibility of paper chromatography have now been adapted for thin layers. The present method is based on peak height measurement with an internal marker correction. Galactose, fructose, D-xylose, and 3-O-methyl glucose can be estimated in addition to glucose, either singly or in combination, within three or four hours, using an initial sample volume of 0·5 ml. With reasonable experience and skill a coefficient of variation of 3 to 6 %, depending on sugar concentration, can be achieved without replication, and the limit of sensitivity is about 0·05 mmol/l. When the performance was compared with an automated glucose oxidase/peroxidase system for glucose and the recovery for the other monosaccharides was calculated, the results were satisfactory.

Disease activity was assessed clinically and erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), orosomucoid, alpha 1-antitrypsin (alpha 1AT) and alpha 2-macroglobulin (alpha 2M) were measured in 65 patients with ankylosing spondylitis (AS). Positive correlations were found between ESR and the acute phase proteins (APP), CRP, orosomucoid and alpha 1AT, but none of these variables correlated with the clinical assessment of activity. No relationship was demonstrated between the protease inhibitor, alpha 2M and clinical activity, ESR or any of the APP. While the treatment of AS remains predominantly symptomatic, routine management of patients should continue to be founded on the clinical assessment of disease activity rather than on laboratory indices of inflammation.

SUMMARY Immunoturbidimetric assays for measuring the apolipoproteins Al and B using the Cobas Bio centrifugal analyser are described. The methods were specific, offered good sensitivity (< 0-05 g/l) and intrabatch variability, with coefficients of variation between 2-4% and 3 5%, and were cost effective. Reference ranges were calculated for a group of civil servants, aged 35 to 55 years.The routine laboratory assessment of the risk and severity of coronary heart disease (CHD) depends on the measurement of total cholesterol, high density lipoprotein cholesterol, and serum triglycerides. Retrospective studies have shown that patients with angiographically defined CHD have significantly higher values of apoliprotein B (apoB) and lower values of apoliprotein Al (apoA 1) than patients without the disease.' These observations have encouraged a recent interest in the measurement of apoA 1 and apoB and their potential use with conventional lipid assays as predictors of risk of CHD. Material and methodsThe assays were performed using the Cobas Bio centrifugal analyser from Roche Products Limited. Welwyn Garden City, Hertfordshire.Reference ranges for the two apolipoproteins were calculated using non-parametric procedures for a group of civil servants (n = 421), aged 35-55 years.Phosphate buffered saline (PBS) at pH7-4, 0-34 g of potassium dihydrogen phosphate dihydrate and 133 g ofdisodium hydrogen phosphate, 9 g sodium chloride, and I g sodium azide were dissolved in distilled water.The pH was adjusted to 7-4 and made to I litre with distilled water. Buffered polyethylene glycol (PEG) and PBS (5% w/v) 5 g PEG 6000, and 200 pl Tween 20 were dissolved and made up to 100 ml with PBS.Anti-human apolipoproteins Al (150 Ml) and B (250 p1) antisera (Boehringer, Mannheim, West Germany) were each added to 6 ml ofPEG/PBS. The appropriate antibody dilution was determined for each batch of antisera.

Adaptation of coenzyme stimulation assays for the nutritional assessment of thiamine, riboflavin and pyridoxine on the Cobas Bio centrifugal analyser are described. Whole blood was collected into acid-citrate dextrose, which preserves the erythrocytes, prior to assay for several days. Washed erythrocytes stored at −70°C and subsequently thawed, showed altered enzyme activities. The methods offer improved precision over existing procedures and take advantage of the high throughput capabilities of the instrumentation.