Quantitative analysis of each of the S-alk(en)yl-L-cysteine sulphoxides was achieved by the following procedure. A methanol : chloroform : water extract of onion tissue was purified by electrophoresis. Alk(en)yl-L-cysteine sulphoxides were separated by thinlayer chromatography (t.l.c,) on commercial silica-gel plates and were reacted with ninhydrin, the spot intensity being measured by an integrating densitometer. The synthetic analogue ( k )-S-1-butyl-L-cysteine sulphoxide was used as an internal standard in each extract.In white bulb onion (cv. Southport White Globe), ( & )-S-1-propyl-L-cysteine sulphoxide is the predominant flavour precursor at a concentration of 2.9 f 0.4 mg g-1 fresh weight. rt -S-1-methyl-L-cysteine sulphoxide and ( 2 ) trans-S-1-propenyl-Lcysteine sulphoxide are present at the lower concentrations of 0.9 f 0.25 mg g-l fresh weight and 0.6 f 0.15 mg g-1 fresh weight respectively.Stable n-butyl, trifluoroacetyl derivatives of standards and of the alk(en)yl-Lcysteine sulphoxides in extracts, were formed. Subsequent g.c.-m.s. enabled parent ions and fragmentation patterns to be recorded and allowed the conclusive identification of the endogenous alk(en)yl-L-cysteine sulphoxides.

Central brain network connections greatly contribute to overall network efficiency. Here we examined whether small vessel disease related white matter alterations in central brain network connections have a greater impact on executive functioning than alterations in non-central brain network connections. Brain networks were reconstructed from diffusion-weighted MRI scans in 72 individuals (75 ± 8 years) with cognitive impairment and small vessel disease on MRI. The centrality of white matter connections in the network was defined using graph theory. The association between the fractional anisotropy (FA) of central versus non-central connections, executive functioning, and markers of small vessel disease was evaluated with linear regression and mediation analysis. Lower FA in central network connections was more strongly associated with impairment in executive functioning than FA in non-central network connections (r=0.41 vs. 0.27; p<0.05). Results were consistent across varying thresholds to define the central subnetwork (>50%–10% connections). Higher small vessel disease burden was associated with lower FA in central as well as non-central network connections. However, only central network FA mediated the relationship between white matter hyperintensity volume and executive functioning (change in regression coefficient after mediation (95% CI): −0.15 (−0.35 to −0.02)). The mediation effect was not observed for FA alterations in non-central network connections (−0.03 (−0.19 to 0.04)). These findings suggest that the centrality of network connections, and thus their contribution to global network efficiency, appears to be relevant for understanding the relationship between small vessel disease and cognitive impairment.

Background Impairment in instrumental activities of daily living (IADL) starts as individuals with amnestic mild cognitive impairment (MCI) transition to Alzheimer’s disease (AD) dementia. However, most IADL scales have not shown IADL alterations in clinically normal (CN) elderly. The objective of this study was to determine which of the IADL-related Everyday Cognition (ECog) scale items are most sensitive for detection of early functional changes. Methods We assessed 290 CN and 495 MCI participants from the Alzheimer’s Disease Neuroimaging Initiative. We performed logistic regression analyses predicting the probability of CN vs. MCI diagnosis using only the 17 participant-based and 17 informant-based ECog items related to IADL. We then performed Cox regression analyses to predict progression from CN to MCI. All analyses were adjusted for demographic characteristics. Results We found that worse performance on “remembering a few shopping items” (participant and informant-based p<0.0001), “remembering appointments” (participant and informant-based p<0.0001), “developing a schedule in advance of anticipated events” (participant-based p=0.007), “balancing checkbook” (participant-based p=0.02), and “keeping mail and papers organized” (informant-based p=0.002) best discriminated MCI from CN. We found that worse performance on “keeping mail and papers organized” (participant-based Hazard Ratio (HR)=2.27, p=0.07) marginally predicted greater hazard of progressing from CN to MCI. Conclusions Our results indicate that a few simple questions targeting early functional changes, addressed either to the individual or informant, can effectively distinguish between CN elderly and individuals with MCI. Additionally, one of the above questions related to organization suggested which CN individuals are likely to progress to MCI.

Particulate fractions prepared from meadow hay, ranging in size from (M to 2 mm, were incubated with rumen digesta from four cannulated Romney sheep fed the same hay. The rates of gas production, lipolysis of corn oil and hydrogenation of linoleic acid were measured.The rate of gas production per g fermentable particles (FP) was approximately 30 % lower with 1-2 mm than with the 0-1-0-4 mm particles. However, per m 2 surface area the rate for the larger particles was found to be approximately 600% greater.The rates of lipolysis of triacylglycerols and hydrogenation of linoleic acid were respectively 25 and 60% higher per g FP and 1100 and 1200% higher per m 2 FP surface area with the 1-2 mm particulate fraction.The same hay particulate fractions were incubated with pure cultures of Ruminococcus flavefaciens, since this organism is active in both lipid metabolism and cellulose fermentation. The rate of gas production and the number of organisms adhering to the particles were determined.The effects of particle size on gas production were similar to those found when incubations were carried out with rumen digesta. Per g FP the rate was 40 % lower with 1-2 mm than with Q-1-0-4 mm particles. However, per m 2 surface area the rate was found to be approximately 450% greater with the former.It was further found that although the density of the bacterial population on 1-2 mm particles was 600% higher than on the 0-1-0-4 mm particles, the rate of gas production per 10" bacteria remained unchanged.We conclude that per m 2 surface area fermentation, lipolysis and hydrogenation were more rapid with particles ranging from 1 to 2 than from 0-1 to 0-4 mm in size. This was due, at least in part, to microbial population density.