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Biomedical subjects

D Benton

Publications and source records attributed to D Benton.

At least 19 recordsLinked to original sources
PubMed1995

The impact of long-term vitamin supplementation on cognitive functioning.

The possibility that the taking of vitamin supplements may influence cognitive functioning was explored. One hundred and twenty-seven young healthy adults took either ten times the recommended daily dose of nine vitamins, or a placebo, under a double-blind procedure, for a year. After 12 months better performance on two measures of attention was found in females who had taken the vitamin supplement, even though the blood status of nine vitamins reached a plateau after 3 months. The use of regression equations demonstrated the association between improved thiamin status and improved performance on a range of measures of cognitive functioning in females rather than males. Although it was not possible to establish the reason for a beneficial response in females rather than males, the evidence that females respond differently to dietary factors was discussed.

Adolescent↗
PubMed1995

The effects of the opiate antagonist naloxone on measures of cellular immunity during rest and brief psychological stress.

This study investigated subjective, cardiovascular, and cellular immune system responses in 20 healthy young men during brief mental arithmetic stress compared with a video-watching control task. The role of endogenous opioids in mediating the immunological change to stress was examined by pre-task administration of the opiate antagonist naloxone. Immune changes were followed over a 1 hr post-task period. The results indicate significant physiological arousal and subjective distress as well as increases in NK cell cytotoxicity, numbers of circulating CD8 suppressor/cytotoxic T cells and NK lymphocytes following mental arithmetic but not the control task. Immune measures generally returned to baseline by 1 hr after the stress. Naloxone did not block the increase in NK cell activity or cell numbers following the stressor and had no effect on the other physiological or subjective measures. Thus, the results do not support endogenous opioids as a primary mechanism for immune changes to this type of acute stress. Naloxone did, however, increase NK cell cytotoxicity during the video task without effecting NK cell numbers, suggesting naloxone itself can increase per-cell NK cytotoxicity. Affective ratings for the week preceding testing were inversely related to the increase in NK cell numbers during mental arithmetic. If the increase in NK cell numbers under brief stress is part of an adaptive response to potential injury, then our data suggest that increases in general distress may impede normal immune system adaptation. Acute stress paradigms may be used as potential probes for investigations of individual differences in immune system responsivity.

Adult↗
PubMed1995

Blood glucose levels selectively influence memory for word lists dichotically presented to the right ear.

The relationship between performance on a dichotic listening task and blood glucose levels was examined. It was predicted that, if the ability of blood glucose to supply the brain with its basic fuel limits performance under conditions of cognitive demand, in a dichotic listening task information directed to the left hemisphere would be particularly susceptible to the level of blood glucose. Via headphones subjects heard lists of words directed to both ears, although randomly they were asked to attend to those directed to one ear. Those receiving a glucose drink recalled more of a list of words directed to the right ear and hence the left hemisphere. Subjects with low baseline blood glucose levels recalled more from the attended ear, and those with high baseline blood glucose more from the unattended ear. In those who received a glucose drink, a fail in blood glucose during the dichotic task was associated with a right ear superiority. The pattern of findings can be explained by the assumptions that under conditions of cognitive demand the supply of glucose to the brain limits performance and that there are individual differences in the ability to efficiently take glucose from the blood stream into the brain.

Adult↗
PubMed1995

Vitamin supplementation for 1 year improves mood.

The possibility that the taking of vitamin supplements may influence mood was explored. One hundred and twenty-nine young healthy adults took either 10 times the recommended daily dose of 9 vitamins, or a placebo, under a double-blind procedure, for a year. Males taking the vitamins differed from those taking the placebo in that they reported themselves as feeling more 'agreeable' after 12 months. After 12 months the mood of females taking the vitamin supplement was significantly improved in that they felt more 'agreeable', more composed and reported better mental health. These changes in mood after a year occurred even though the blood status of 9 vitamins reached a plateau after 3 months: this improvement in mood was associated in particular with improved riboflavin and pyridoxine status. In females baseline thiamin status was associated with poor mood and an improvement in thiamin status after 3 months was associated with improved mood.

Adolescent↗
PubMed1994

Blood glucose influences memory and attention in young adults.

There is evidence from animal studies that increased blood glucose levels are associated with improved memory and attention. Although previous studies have found human memory to be facilitated by the administration of glucose, attentional measures have been largely ignored. Therefore the impact of a glucose drink, or a placebo, on the Rapid Information Processing Task and the Stroop Task was examined. The reaction times of those taking the Rapid Information Processing Task were faster both during the baseline period and after a glucose drink if the blood glucose values were high. With the Stroop task the ability to perform the most cognitively demanding sub-test was selectively enhanced if blood glucose values were increasing prior to starting the test. The ability to recall words from a word list was greater if a glucose drink had been consumed, although primary and recency were not differentially influenced. The possibility is discussed that higher levels of brain glucose are associated with better memory and attention.

Adult↗
PubMed1994

The impact of raising blood glucose on reaction times.

Although previous studies have demonstrated enhanced mood and memory in humans following the consumption of glucose drinks, the effect of increasing blood glucose levels on other tasks has not received the same attention. In the present study, inspection time was unaffected by glucose drinks and blood glucose levels. However, increasing blood glucose levels resulted in faster decision times when reaction time was measured. It is concluded that speed of processing is faster when the availability of glucose to the brain is increased. The possibility that the glucose-induced improvements in reaction time reflect an increased synthesis of acetylcholine is discussed.

Adolescent↗
PubMed1993

Blood glucose and human memory.

As it has been suggested that blood glucose might play a role in the action of some cognitive enhancing drugs, the influence of glucose containing drinks on human memory was examined. In a double-blind study the influence was examined of a drink containing 50 g glucose, or a placebo, on the ability to recall a word list. There was a significant correlation between blood glucose values and the number of words recalled. Those whose blood glucose levels were increasing remembered significantly more words than those whose blood glucose levels were falling. No relationship was found between blood glucose and performance on a test of spatial memory. In a second study blood glucose levels were raised for 2 h by taking a series of glucose-containing drinks. The number of words recalled from a word list correlated significantly with blood glucose levels but not with recall of a Wechsler story. The glucose-induced improvement in memory did not occur only in those whose blood glucose levels were initially low; rather it occurred irrespective of initial blood glucose level.

Adult↗
PubMed1993

Is raised blood glucose associated with the relief of tension?

A series of three studies examined the influence of glucose drinks and increasing blood glucose levels on mood. Experiment one considered the short-term effect of a glucose containing drink on mood in young adults: a glucose drink in the morning and higher blood glucose levels were both associated with feeling less tense. Higher blood glucose was also correlated with greater self-reported energy. In the second experiment high blood glucose levels were sustained for 2 hr by repeatedly taking a glucose containing drink. Again higher blood glucose levels were associated with reports of less tension. In a final study subjects were placed in a frustrating situation. The consumption of a glucose drink resulted in fewer negative responses, following a negative statement from the experimenter, in subjects who had fasted over-night. It was concluded that higher blood glucose levels are associated with feeling less tense.

Adaptation, Psychological↗
PubMed1993

Myxococcus xanthus encodes an ATP-dependent protease which is required for developmental gene transcription and intercellular signaling.

The bsgA gene of Myxococcus xanthus plays an essential role in the regulation of early gene expression during fruiting body formation and sporulation. bsgA mutants behave as though unable to initiate a required cell-cell interaction and consequently fail to transcribe normal levels of many developmentally induced genes. We determined the nucleotide sequence of bsgA, which predicts a single gene encoding a 90.4-kDa protein. The deduced BsgA protein shares 45 and 48% amino acid identity with the lon genes of Escherichia coli and Bacillus brevis, respectively. The cloned bsgA gene was expressed in E. coli, and the BsgA protein was partially purified and found, like its E. coli homolog, to be an ATP-dependent protease. Thus, the basis for the phenotype of bsgA mutants is likely to be a defect in intracellular proteolysis.

ATP-Dependent Proteases↗
PubMed1992

IQ and diet.

Explore the source record for details and available documents.

Child↗
PubMed1992

Participation in physical activity and cardiovascular fitness have different effects on mental health and mood.

The cardiovascular fitness, blood pressure, resting pulse, lung capacity and body fat of 246 subjects were measured and each subject completed activity, mental health and mood questionnaires. The results of this study support the hypothesis that participation in physical activity, rather than cardiovascular fitness, is the factor associated with better mental health and mood. Higher levels of physical activity were associated with better mood scores unless the individuals were unfit. This research has implications for how physical activity is prescribed; the emphasis needs to be on performing physical activity rather than improving fitness and should not be beyond the physical capabilities of the individual.

Adaptation, Psychological↗
PubMed1992

Breakfast, blood glucose and memory.

The hypothesis that blood glucose levels influence memory was re-examined. The performance on two memory tests was quicker when breakfast had been taken, suggesting that the ability to retrieve memories had been facilitated. Performance on a spatial memory test correlated significantly with blood glucose levels.

Adult↗