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Myrosinase activity in partially purified extracts of 12 cruciferous vegetables and an acetone powder preparation of Sinapis alba L. (white mustard) was determined by the initial rate of glucose formation from glucosinolate hydrolysis using a coupled assay. Of the species studied Raphanus sativus L. (radish, 12.8+0.7pmol min-' g-' powdered tissue) had the greatest myrosinase activity, and Brassica campestris L. ssp. rapifera (turnip) and Nasturtium officinalis R.Br. (watercress) ( 0 . 6 f 0 . 1 and 0.8k0.03 pmol min-' g-' powdered tissue respectively) the least. The sub-species of Brassica oleracea studied all had similar myrosinase activity (ca 2.5-tO.2prnol min-'g-' powdered tissue) except B. oleracea L. var. gemmifera D.C. (Brussels sprouts) and B. oleracea L. var. capitata L. (white cabbage) which had higher activities (7.6f0.1 and 5.2+0.2pmol min-' g-' powdered tissue respectively). The effect of ascorbate concentration upon the myrosinase activity of six of the crucifers studied and the white mustard preparation, revealed that the ascorbate concentration necessary to promote maximal activity vaned with species. A concentration of 0 . 9 m~ ascorbate maximally activated radish and turnip myrosinase, while red cabbage, watercress, white mustard and Brussels sprouts were maximally activated at 2.0, 3.0, 5.0 and 0.7-1.0m~ ascorbate respectively. Two peaks of maximal myrosinase activity, occurring between 0.9 and 1.OmM and at 3 . 0 m~ ascorbate, were found for B. oleracea L. var. botrytis L. subvar. cauliflora D.C. (cauliflower).

When assessing the relative motion of the lumbar spine and hips in standing forward flexion, there was measurable difference between asymptomatic men and a group of chronic low back pain patients. In particular, two subgroups of individuals with chronic low back pain appeared; one moved relatively similarly to the asymptomatic group, whereas the other sub-group demonstrated reduced hip mobility. These findings indicate the importance of assessing the lumbar and hip flexion motion in chronic low back pain patients to determine if a movement abnormality is present.

The effects of dry extrusion of mixtures of rapeseed and soya bean on total and individual glucosinolates, selected glucosinolate hydrolysis products, myrosinase, sinapine and tannins have been compared with those of more conventional processing, e.g. lime treatment, micronisation and ammoniation. Extrusion at 150°C effectively inactivated myrosinase but had relatively little effect on glucosinolate content unless chemicals were added before extrusion; the most effective combination, 5% alkali+l% ferrous sulphate, reduced the total glucosinolate content by 80%. Under the latter conditions very high (>30,umolg-' defatted meal) levels of nitriles were produced, leading to the suggestion that nitriles in addition to oxazolidine-2-thione and isothiocyanates be used to monitor the effectiveness of processing techniques. None of the extrusion conditions showed any significant effect on reducing sinapine or tannin contents. In view of the chemical data presented, and the probable adverse effects which the processing conditions selected have on the nutritional value of the processed meal it seems unlikely that extrusion will play a significant role in rapeseed detoxification.

This study quantified aflatoxin (AFB1, AFG1 and AFQ1) by enzyme-linked immunosorbent assay in human cord sera obtained at birth and in serum obtained immediately after birth from the mother. The subjects of the study were residents of Songkhla, Thailand. Of the 35 samples of cord sera, 17 (48%) contained aflatoxin in concentrations from 0.064 to 13.6, mean 3.1 nmol/ml. By comparison only two (6%) of 35 maternal sera contained aflatoxin (mean 0.62 nmol/ml). These results demonstrate transplacental transfer and concentration of aflatoxin by the feto-placental unit which may be of biological importance. Aflatoxins are mutagenic, carcinogenic and teratogenic and cause immunosuppression in animals. The implications of these findings are potentially profound and deserve further study.

1. Isoflavones are naturally occurring oestrogenic compounds found in plants, where they exist in the glycosylated form. A proportion of ingested glycosides appears to be absorbed in the upper gastrointestinal tract, where enterocytes play an important role in their metabolism. 2. One hypothesis is that ingestion may involve hydrolysis by the luminally exposed enzyme lactase phlorizin hydrolase (LPH), an enzyme expressed specifically at the small intestinal brush border. 3. Using an everted sac preparation of rat jejunum and an inhibitor of LPH, we investigated the absorption of daidzein-O(7)-glucoside (daidzin) and the effect of LPH inhibition on this process. It was demonstrated that LPH plays a major role in the deglycosylation of daidzin. 4. The hydrolysis product, daidzein, is absorbed by epithelial cells and glucuronidated to daidzein-O(7)-glucuronide, which is subsequently exported primarily to the serosal (vascular) side of the tissue rather than to the luminal side. 5. A small but significant proportion of the intact glycoside is also transferred to the serosal compartment, and in the presence of an LPH inhibitor this was enhanced with a corresponding reduction in deglucosylation and glucuronidation. 6. The results indicate that that LPH plays an important role in the metabolism of glycosylated phytochemicals, and that the expression and activity of this enzyme in the small intestine can modify the profile of metabolites appearing in the circulation.

Isopropylmalate synthase (IPMS) is a key enzyme in the biosynthesis of the essential amino acid leucine, and thus primary metabolism. In Arabidopsis, the functionally similar enzyme, methythiolalkylmalate synthase (MAM), is an important enzyme in the elongation of methionine prior to glucosinolate (GSL) biosynthesis, as part of secondary metabolism. We describe the cloning of an IPMS gene from Brassica, BatIMS, and its functional characterisation by heterologous expression in E. coli and Arabidopsis. Over expression of BatIMS in Arabidopsis resulted in plants with an aberrant phenotype, reminiscent of mutants in GSL biosynthesis. Metabolite analyses showed that these plants had both perturbed amino acid metabolism and enhanced levels of GSLs. Microarray profiling showed that BatIMS over expression caused up regulation of the genes for methionine-derived GSL biosynthesis, and down regulation of genes involved in leucine catabolism, in addition to perturbed expression of genes involved in auxin and ethylene metabolism. The results illustrate the cross talk that can occur between primary and secondary metabolism within transgenic plants.