The effects of a mid-morning bout of exercise on adolescents' cognitive function

The aim of the present study was to examine the effects of a mid-morning bout of exercise on adolescents’ cognitive function in a randomised crossover design where each participant completed two experimental trials. Forty-five adolescents (13.3±0.3 years old), undertook a bout of exercise (ten repeats of level one of the multi-stage fitness test, 30s rest between repeats; exercise trial) or continued to rest (resting trial). A battery of cognitive function tests assessing visuo-motor speed, executive function and working memory (visual search test, Stroop test and Sternberg paradigm, respectively) was completed 30 min before and 45 min following the exercise. Average heart rate during exercise was 172±17 beats/min. On the visual search test, there was a greater improvement in response times across the morning on the exercise trial (t=2.6, p=0.009). However, this improvement in response times was combined with a greater decrease in accuracy on the exercise trial (z=2.0, p=0.044). On the Sternberg paradigm there was a greater improvement in response times across the morning following exercise when compared to resting (t=2.6, p=0.010). The mid-morning bout of exercise did not affect Stroop test performance. These improvements in response times are most likely the result of a general speeding up of responses across several cognitive domains, because response times were improved similarly across two different domains and across all test complexity levels, rather than being restricted to the specific high cognitive load levels. Accordingly, exercise in school settings may help to improve cognitive function in adolescents during the school morning

Positive and Negative Experiences of Social Support and Risk of Dementia in Later Life: An Investigation Using the English Longitudinal Study of Ageing.

BACKGROUND: Having a network of close relationships may reduce the risk of developing dementia. However, social exchange theory suggests that social interaction entails both rewards and costs. The effects of quality of close social relationships in later life on the risk of developing dementia are not well understood. OBJECTIVE: To investigate the effects of positive and negative experiences of social support within key relationships (spouse or partner, children, other immediate family, and friends) on the risk of developing dementia in later life. METHODS: We analyzed 10-year follow up data (2003/4 to 2012/13) in a cohort of 10,055 dementia free (at baseline) core participants aged 50 years and over from the English Longitudinal Study of Ageing (ELSA). Incidence of dementia was identified from participant or informant reported physician diagnosed dementia or overall score of informant-completed IQCODE questionnaire. Effects of positive and negative experiences of social support measured at baseline on risk of developing dementia were investigated using proportional hazards regression accommodating interval censoring of time-to-dementia. RESULTS: There were 340 (3.4%) incident dementia cases during the follow-up. Positive social support from children significantly reduced the risk of dementia (hazard ratio, HR = 0.83, p = 0.042, 95% CI: 0.69 to 0.99). Negative support from other immediate family (HR = 1.26, p = 0.011, CI: 1.05 to 1.50); combined negative scores from spouse and children (HR = 1.23, p = 0.046, CI: 1.004 to 1.51); spouse, children, and other family (HR = 1.27, p = 0.021, CI = 1.04 to 1.56); other family & friends (HR = 1.25, p = 0.033, CI: 1.02 to 1.55); and the overall negative scores (HR = 1.31, p = 0.019, CI: 1.05 to 1.64) all were significantly associated with increased risk of dementia. CONCLUSION: Positive social support from children is associated with reduced risk of developing dementia whereas experiences of negative social support from children and other immediate family increase the risk. Further research is needed to better understand the causal mechanisms that drive these associations

Breakfast glycaemic index and cognitive function in adolescent school children

It has been suggested that a low-glycaemic index (GI) breakfast may be beneficial for some elements of cognitive function (e.g. memory and attention), but the effects are not clear, especially in adolescents. Thus, the aim of the present study was to examine the effects of a low-GI breakfast, a high-GI breakfast and breakfast omission on cognitive function in adolescents. A total of fifty-two adolescents aged 12–14 years were recruited to participate in the study. Participants consumed a low-GI breakfast, a high-GI breakfast or omitted breakfast. A battery of cognitive function tests was completed 30 and 120 min following breakfast consumption and capillary blood samples were taken during the 120 min postprandial period. The findings show that there was a greater improvement in response times following a low-GI breakfast, compared with breakfast omission on the Stroop (P=0·009) and Flanker (P=0·041) tasks, and compared with a high-GI breakfast on the Sternberg paradigm (P=0·013). Furthermore, accuracy on all three tests was better maintained on the low-GI trial compared with the high-GI (Stroop: P=0·039; Sternberg: P=0·018; Flanker: P=0·014) and breakfast omission (Stroop: P<0·001; Sternberg: P=0·050; Flanker: P=0·014) trials. Following the low-GI breakfast, participants displayed a lower glycaemic response (P<0·001) than following the high-GI breakfast, but there was no difference in the insulinaemic response (P=0·063) between the high- and low-GI breakfasts. Therefore, we conclude that a low-GI breakfast is most beneficial for adolescents' cognitive function, compared with a high-GI breakfast or breakfast omission

Sex differences in adolescents' glycaemic and insulinaemic responses to high and low glycaemic index breakfasts: a randomised control trial

During puberty young people undergo significant hormonal changes which affect metabolism and, subsequently, health. Evidence suggests there is a period of transient pubertal insulin resistance, with this effect greater in girls than boys. However, the response to everyday high and low glycaemic index (GI) meals remains unknown. Following ethical approval, forty adolescents consumed a high GI or low GI breakfast, in a randomised cross-over design. Capillary blood samples were taken during a 2-h postprandial period, examining the glycaemic and insulinaemic responses. Maturity offset and homoeostatic model assessment (HOMA) were also calculated. The glycaemic response to the breakfasts was similar between boys and girls, as shown by similar peak blood glucose concentrations and incremental AUC (IAUC) following both high and low GI breakfasts (all P> 0·05). Girls exhibited a higher peak plasma insulin concentration 30 min post-breakfast following both high GI (P=0·043, g=0·69) and low GI (P =0·010, g =0·84) breakfasts, as well as a greater IAUC following high GI (P=0·041, g =0·66) and low GI (P =0·041, g =0·66) breakfasts. HOMA was positively correlated with the insulinaemic responses (all P<0·0005) and maturity offset (P =0·037). The findings of the present study suggest that pubertal insulin resistance affects the postprandial insulinaemic responses to both high and low GI meals. Specifically, girls exhibit a greater insulinaemic response than boys to both meals, despite similar glycaemic responses. This study is the first to report the glycaemic and insulinaemic responses to everyday meals in boys and girls, supporting the recommendation for young people to base their diet on low GI carbohydrates

Effect of exercise duration on postprandial glycaemic and insulinaemic responses in adolescents

High-intensity intermittent exercise (HIIE) is a potential intervention to manage hyperglycaemia and insulin resistance in adolescents. The aim of this study was to determine the optimum duration of HIIE to reduce postprandial glycaemic and insulinaemic responses in adolescents and the longevity of the response. Thirty-nine participants (12.4 ± 0.4 year) completed a 30- and 60-min exercise trial (Loughborough Intermittent Shuttle Test) and a rested control trial in a randomised crossover design. Capillary blood samples were taken at baseline, immediately and 1-h post-exercise; and 30, 60 and 120 min following a standardised lunch (day one) and a standardised breakfast 24-h post-exercise. Plasma insulin total area under the curve (tAUC) following lunch was lower following 60-min HIIE (21,754 ± 16,861 pmol·L−1 × 120 min, p = 0.032) and tended to be lower following 30-min HIIE (24,273 ± 16,131 pmol·L−1 × 120 min, p = 0.080), when compared with the resting condition (26,931 ± 21,634 pmol·L−1 × 120 min). Blood glucose concentration was lower 1-h post-exercise following 30-min HIIE (3.6 ± 0.6 mmol·L−1) when compared to resting (4.1 ± 0.9 mmol·L−1, p = 0.001). Blood glucose and plasma insulin concentration did not differ across trials on day two. Shorter bouts of HIIE (30-min), as well as a 60-min bout, reduced the postprandial insulinaemic response to lunch, an ecologically valid marker of insulin sensitivity. As the beneficial effects of HIIE were limited to 3 h post-exercise, adolescents are recommended to engage daily HIIE to enhance metabolic health

Predictors of postprandial glycaemia, insulinaemia and insulin resistance in adolescents

Postprandial glycaemia and insulinaemia are important risk factors for type 2 diabetes. The prevalence of insulin resistance in adolescents is increasing, but it is unknown how adolescent participant characteristics such as BMI, waist circumference, fitness and maturity offset may explain responses to a standard meal. The aim of the present study was to examine how such participant characteristics affect the postprandial glycaemic and insulinaemic responses to an ecologically valid mixed meal. Data from the control trials of three separate randomised, crossover experiments were pooled, resulting in a total of 108 participants (52 boys, 56 girls; age: 12.5±0.6 y; BMI: 19.05±2.66 kg·m-2). A fasting blood sample was taken for the calculation of fasting insulin resistance, using the HOMA-IR model. Further capillary blood samples were taken before and 30-, 60- and 120-min after a standardised lunch, providing 1.5 g.kg-1 body mass of carbohydrate, for the quantification of blood glucose and plasma insulin total area under the curve (tAUC). Hierarchical multiple linear regression demonstrated significant predictors for plasma insulin tAUC were waist circumference, physical fitness and HOMA-IR (F(3, 98)=36.78, p<.001, Adj. R2=.515). The variance in blood glucose tAUC was not significantly explained by the predictors used (F(7, 94)=1.44, p=.198). Significant predictors for HOMA-IR were BMI and maturity offset (F(2, 102)=14.06, p<.001, Adj. R2=.021). In summary, the key findings of the study are that waist circumference, followed by physical fitness, best explained the insulinemic response to an ecologically valid standardised meal in adolescents. This has important behavioural consequences because these variables can be modified

Effect of football activity and physical fitness on information processing, inhibitory control and working memory in adolescents

Background: Whilst an acute bout of exercise has been shown to enhance subsequent cognition, including in adolescents, the effects of team games (of which Football is the most popular) has received little attention. Therefore, this study examined: the effect of an acute bout of outdoor Football activity on information processing, inhibitory control, working memory and circulating brain-derived neurotrophic factor (BDNF) in adolescents; the effect of physical fitness on cognition and; the moderating effect of physical fitness on the acute exercise responses. Methods: Following familiarisation, 36 adolescents (16 girls) took part in two trials (60-min Football and 60-min seated rest) separated by 7-d in a counterbalanced, crossover design. Information processing and inhibitory control (Stroop Test), and working memory (Sternberg Paradigm) were assessed 30-min before exercise/rest and immediately, 45- and 90-min post-exercise/rest. Capillary blood samples were obtained before exercise/rest and up to 120-min post-exercise/rest. The median split of distance covered on the MSFT was used to divide the group into high- and low-fit groups. Results: Performance on the cognitive function tasks was similar between Football and seated rest (trial*time interactions; all p > .05). However, the high-fit group had overall quicker response times on both levels of the Stroop Task and all three levels of the Sternberg Paradigm (main effect of fitness; all p  .05). Conclusion: The present study shows that higher levels of physical fitness are beneficial for cognitive function and provides novel evidence that an ecologically valid, and popular, form of exercise is beneficial for working memory following exercise, in high-fit participants only

Holistic process development to mitigate proteolysis of a subunit rotavirus vaccine candidate produced in Pichia pastoris by means of an acid pH pulse during fed‐batch fermentation

To meet the challenges of global health, vaccine design and development must be reconsidered to achieve cost of goods as low as 15¢ per dose. A new recombinant protein‐based rotavirus vaccine candidate derived from non‐replicative viral subunits fused to a P2 tetanus toxoid CD4(+) T cell epitope is currently under clinical development. We have sought to simplify the existing manufacturing process to meet these aims. To this end, we have taken a holistic process development approach to reduce process complexity and costs while producing a product with the required characteristics. We have changed expression system from Escherichia coli to Pichia pastoris, to produce a secreted product, thereby reducing the number of purification steps. However, the presence of proteases poses challenges to product quality. To understand the effect of fermentation parameters on product quality small‐scale fermentations were carried out. Media pH and fermentation duration had the greatest impact on the proportion of full‐length product. A novel acidic pH pulse strategy was used to minimize proteolysis, and this combined with an early harvest time significantly increased the proportion of full‐length material (60–75%). An improved downstream process using a combination of CIEX and AIEX to further reduce proteases, resulted in maintaining product quality (95% yield)

Reaching back: the relative strength of the retroactive emotional attentional blink

Visual stimuli with emotional content appearing in close temporal proximity either before or after a target a stimulus can hinder conscious perceptual processing of the target via an emotional attentional blink (EAB). This occurs for targets that appear after the emotional stimulus (forward EAB) and for those appearing before the emotional stimulus (retroactive EAB). Additionally, the traditional attentional blink (AB) occurs because detection of any target hinders detection of a subsequent target. The present study investigated the relations between these different attentional processes. Rapid sequences of landscape images were presented to thirty-one male participants with occasional landscape targets (rotated images). For the forward EAB, emotional or neutral distractor images of people were presented before the target; for the retroactive EAB, such images were also targets and presented after the landscape target. In the latter case, this design allowed investigation of the AB as well. Erotic and gory images caused more EABs than neutral images, but there were no differential effects on the AB. This pattern is striking because while using different target categories (rotated landscapes, people) appears to have eliminated the AB, the retroactive EAB still occurred, offering additional evidence for the power of emotional stimuli over conscious attention

Human Cytomegalovirus: detection of congenital and perinatal infection in Argentina

BACKGROUND: Human cytomegalovirus (CMV) is one of the most commonly found agents of congenital infections. Primary maternal infection is associated with risk of symptomatic congenital diseases, and high morbidity is frequently associated with very low birth weight. Neonates with asymptomatic infection develop various sequelae during infancy. This is the first Argentine study performed in neonates with congenital and postnatal HCMV infection. The purpose of this study was to evaluate the performance of the polymerase chain reaction (PCR) technique with different pairs of primers, to detect cytomegalovirus isolated in tissue cultures and directly in urine and dried blood spot (DBS) specimens. Results were compared with IgM detection. METHODS: The study was performed between 1999 and 2001 on routine samples in the Laboratory. A total of 61 urine and 56 serum samples were selected from 61 newborns/infants, 33 patients whose samples were analyzed during the first two to three weeks of life were considered congenital infections; the remaining 28 patients whose samples were taken later than the third week were grouped as perinatal infections, although only in 4 the perinatal transmission of infection was determined unequivocally Cytomegalovirus diagnosis was made by isolating the virus from urine samples in human foreskin fibroblast cells. Three different primer pairs directed to IE, LA and gB genes were used for the HCMV PCR assay in viral isolates. Subsequently, PCR and nested PCR (nPCR) assays with gB primers were performed directly in urine and in 11 samples of dried blood spot (DBS) on Guthrie Card, these results were then compared with serology. RESULTS: The main clinical manifestations of the 33 patients with congenital infection were purpura, jaundice, hepatomegaly and anaemia. Three patients presented low birth weight as single symptom, 10, intracranial calcifications, and 2, kidney failure. In the 28 patients grouped as with perinatal infection, anaemia, hepatosplenomegaly and enzymatic alteration were predominant, and 4 patients were HIV positive. The primers used to amplify the gB region had a PCR positivity rate of 100%, whereas those that amplified IE and LA regions had a PCR positivity rate of 54% and 61% respectively, in CMV isolates. Amplification by PCR of urine samples (with no previous DNA extraction), using primers for the gB region, detected 34/61 positive samples. Out of the 33 samples from patients with congenital infection, 24 (73%) were positive. When nPCR was used in these samples, all were positive, whereas in the remaining 28 patients, two negative cases were found. Cytomegalovirus DNA detection in 11 samples was also carried out in DBS: 7 DBS samples were positive and 4 were negative. CONCLUSIONS: Primers directed to the gB fragment region were the best choice for the detection of CMV DNA in positive isolates. In congenital infections, direct PCR in urine was positive in a high percentage (73%) of samples; however, in patients grouped as with perinatal infection only 36% of the cases were positive. With n-PCR, total sample positivity reached 97%. PCR technique performed in DBS allowed identifying congenital infection in four patients and to be confirmed in 3. These results show the value of nPCR for the detection of all cases of CMV infection. The assay offers the advantage that it may be performed within the normal working day and provides reliable results in a much shorter time frame than that required for either traditional tissue culture or the shell-viral assay