Dietary patterns and cognitive decline in an Australian study of ageing.

The aim of this paper was to investigate the association of three well-recognised dietary patterns with cognitive change over a 3-year period. Five hundred and twenty-seven healthy participants from the Australian Imaging, Biomarkers and Lifestyle study of ageing completed the Cancer Council of Victoria food frequency questionnaire at baseline and underwent a comprehensive neuropsychological assessment at baseline, 18 and 36 months follow-up. Individual neuropsychological test scores were used to construct composite scores for six cognitive domains and a global cognitive score. Based on self-reported consumption, scores for three dietary patterns, (1) Australian-style Mediterranean diet (AusMeDi), (2) western diet and (3) prudent diet were generated for each individual. Linear mixed model analyses were conducted to examine the relationship between diet scores and cognitive change in each cognitive domain and for the global score. Higher baseline adherence to the AusMeDi was associated with better performance in the executive function cognitive domain after 36 months in apolipoprotein E (APOE) ɛ4 allele carriers (P<0.01). Higher baseline western diet adherence was associated with greater cognitive decline after 36 months in the visuospatial cognitive domain in APOE ɛ4 allele non-carriers (P<0.01). All other results were not significant. Our findings in this well-characterised Australian cohort indicate that adherence to a healthy diet is important to reduce risk for cognitive decline, with the converse being true for the western diet. Executive function and visuospatial functioning appear to be particularly susceptible to the influence of diet.

Bacterial biofilm formation under microgravity conditions.

Although biofilm formation is widely documented on Earth, it has not been demonstrated in the absence of gravity. To explore this possibility, Pseudomonas aeruginosa, suspended in sterile buffer, was flown in a commercial payload on space shuttle flight STS-95. During earth orbit, biofilm formation was induced by exposing the bacteria to sterile media through a 0.2-microm (pore size) polycarbonate membrane. Examination of these membranes by confocal microscopy revealed biofilms to be present and that these biofilms could persist in spite of vigorous agitation. These results represent the first report of biofilm formation under microgravity conditions.

Plasmid-linked maltose utilization in Lactobacillus ssp.

Five strains of Lactobacillus plantarum and 4 strains of Lactobacillus ssp. isolated from fresh meat contained between 1 and 5 plasmids ranging in Mr from 1.3 to 49 MDa. Plasmid-curing studies suggested that maltose utilization is associated with a 49 MDa plasmid (pML291) in Lactobacillus sp. DB29 and 34.5 MDa plasmids in Lactobacillus ssp. DB27, DB28 and DB31. Restriction digestion of pML291 and a putative plasmid deletion derivative, pML292, isolated from a maltose negative mutant of DB29, generated common restriction fragments. Southern blot DNA-DNA hybridization using pML 291 as a probe indicated that there is strong homology between putative maltose plasmids.

Sequence in which the amino acids on corn (Zea mays) become limiting for growing rats.

Three 21-day feeding experiments were conducted to determine the sequence in which the amino acids of corn become limiting for the growth of young rats. Diets consisted of corn fortified with minerals and vitamins, and supplemented with various combinations of essential amino acids. On the basis of improvements in growth rate and feed efficiency, the sequence of limiting amino acids in corn was determined to be: (1st) lysine and tryptophan--colimiting, (3rd) threonine, (4th) isoleucine, (5th) valine, (6th) methionine, and (7th) possibly histidine and phenylalanine--colimiting. Changes in blood urea levels generally confirmed this sequence. There was no limitation of either arginine or leucine, or of nonspecific nitrogen. Weight gains and feed efficiencies of rats fed a corn diet supplemented with the eight limiting amino acids were equivalent to published values for rats fed nutritionally adequate diets.