Moderate and heavy metabolic stress interval training improve arterial stiffness and heart rate dynamics in humans

Traditional continuous aerobic exercise training attenuates age-related increases of arterial stiffness, however, training studies have not determined whether metabolic stress impacts these favourable effects. Twenty untrained healthy participants (n = 11 heavy metabolic stress interval training, n = 9 moderate metabolic stress interval training) completed 6 weeks of moderate or heavy intensity interval training matched for total work and exercise duration. Carotid artery stiffness, blood pressure contour analysis, and linear and non-linear heart rate variability were assessed before and following training. Overall, carotid arterial stiffness was reduced (p < 0.01), but metabolic stress-specific alterations were not apparent. There was a trend for increased absolute high-frequency (HF) power (p = 0.10) whereas both absolute low-frequency (LF) power (p = 0.05) and overall power (p = 0.02) were increased to a similar degree following both training programmes. Non-linear heart rate dynamics such as detrended fluctuation analysis $({| {1 - \alpha_{1} }|})$ also improved (p > 0.05). This study demonstrates the effectiveness of interval training at improving arterial stiffness and autonomic function, however, the metabolic stress was not a mediator of this effect. In addition, these changes were also independent of improvements in aerobic capacity, which were only induced by training that involved a high metabolic stress.     

Smartphones for Smarter Delivery of Mental Health Programs: A Systematic Review

Background

The rapid growth in the use of mobile phone applications (apps) provides the opportunity to increase access to evidence-based mental health care.

Objective

Our goal was to systematically review the research evidence supporting the efficacy of mental health apps for mobile devices (such as smartphones and tablets) for all ages.

Methods

A comprehensive literature search (2008-2013) in MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, PsycINFO, PsycTESTS, Compendex, and Inspec was conducted. We included trials that examined the effects of mental health apps (for depression, anxiety, substance use, sleep disturbances, suicidal behavior, self-harm, psychotic disorders, eating disorders, stress, and gambling) delivered on mobile devices with a pre- to posttest design or compared with a control group. The control group could consist of wait list, treatment-as-usual, or another recognized treatment.

Results

In total, 5464 abstracts were identified. Of those, 8 papers describing 5 apps targeting depression, anxiety, and substance abuse met the inclusion criteria. Four apps provided support from a mental health professional. Results showed significant reductions in depression, stress, and substance use. Within-group and between-group intention-to-treat effect sizes ranged from 0.29-2.28 and 0.01-0.48 at posttest and follow-up, respectively.

Conclusions

Mental health apps have the potential to be effective and may significantly improve treatment accessibility. However, the majority of apps that are currently available lack scientific evidence about their efficacy. The public needs to be educated on how to identify the few evidence-based mental health apps available in the public domain to date. Further rigorous research is required to develop and test evidence-based programs. Given the small number of studies and participants included in this review, the high risk of bias, and unknown efficacy of long-term follow-up, current findings should be interpreted with caution, pending replication. Two of the 5 evidence-based mental health apps are currently commercially available in app stores.     

Infants use relative numerical group size to infer social dominance

Detecting dominance relationships, within and across species, provides a clear fitness advantage because this ability helps individuals assess their potential risk of injury before engaging in a competition. Previous research has demonstrated that 10- to 13-mo-old infants can represent the dominance relationship between two agents in terms of their physical size (larger agent = more dominant), whereas younger infants fail to do so. It is unclear whether infants younger than 10 mo fail to represent dominance relationships in general, or whether they lack sensitivity to physical size as a cue to dominance. Two studies explored whether infants, like many species across the animal kingdom, use numerical group size to assess dominance relationships and whether this capacity emerges before their sensitivity to physical size. A third study ruled out an alternative explanation for our findings. Across these studies, we report that infants 6–12 mo of age use numerical group size to infer dominance relationships. Specifically, preverbal infants expect an agent from a numerically larger group to win in a right-of-way competition against an agent from a numerically smaller group. In addition, this is, to our knowledge, the first study to demonstrate that infants 6–9 mo of age are capable of understanding social dominance relations. These results demonstrate that infants’ understanding of social dominance relations may be based on evolutionarily relevant cues and reveal infants’ early sensitivity to an important adaptive function of social groups.Competition for valuable resources such as mates, food, and territory (1) is commonplace across the animal kingdom. To minimize the cost of fighting (e.g., energy spent and personal injury or death), natural selection appears to have favored the emergence of cognitive adaptations that help individuals predict whether they stand a chance against an opponent (2–5). For example, many species, including ants, bees, birds, chimpanzees, and humans, appear to represent dominance relationships among conspecifics and use this information to decide whether to engage in or avoid a physical conflict (6–10). One such cue often associated with dominance ranking is physical size, with larger individuals often benefiting from greater strength and power over smaller individuals. Natural selection has also favored adaptations that exploit this inference, such that under threat, certain species adopt postures that make them appear bigger (11, 12) in order to intimidate an opponent.Underscoring the possibility that representations of social dominance may be part of humans’ evolved psychology, recent evidence has demonstrated that preverbal human infants infer social dominance relationships by comparing the physical size of two competing agents (13). In this earlier study, infants were introduced to two agents (one twice as large as the other), each with the goal of crossing to the opposite side of a platform. When both agents tried to cross the platform at the same time, their paths conflicted. Infants were shown two scenarios: one in which the larger agent yielded to the smaller agent, and one in which the smaller agent yielded to the larger agent. Although 10–13 mo olds expected a smaller agent to yield to a larger agent, younger infants (8–9 mo) failed to show any systematic belief about which agent should prevail. Therefore, only older infants were able to use the relative physical size of two competing agents to infer which one would get the right of way.Because younger infants did not reliably use physical size as a cue to social dominance, it remains unclear whether the younger infants were incapable of representing dominance relationships in general, or if they lacked sensitivity to this particular cue. To address this issue, the present study examined whether infants’ understanding of social dominance extends to cues beyond physical size—namely, to numerical group size, and if so, whether such a sensitivity emerges earlier in development.For many group-living animals, including social insects (7), wolves (14), hyenas (15), lions (16), primates (6), and human children and adults (5, 10), the ability to infer social dominance by assessing the numerical size of one’s own group relative to another is particularly important for survival (15, 17). The importance of this capacity to evaluate one’s own group size relative to another is illustrated by groups of chimpanzees patrolling their territory borders. To advertise the numerical strength of their group to others (18, 19) and deter opposing groups from approaching (20, 21), both males and females will engage noisy pant-hoot calling. In general, both chimpanzees and lions are more likely to approach if they outnumber intruders, but will stay silent and refrain from engaging in intergroup conflict if they do not (6, 16, 22, 23). Consequently, a group’s decision to engage in competition is more likely to occur if there are more individuals in one’s own group than in the opposing group (22, 24). Further, the relationship between numerical group size and inferences about social dominance has also been recently observed among children ages 6–8 y (5). School-aged children predicted that alliance strength would determine the likelihood of success in a conflict, such that two individuals aligned together were expected to win against a single individual. Coupled with the evidence reviewed from behavioral ecology, numerical group size may serve as an evolutionarily relevant cue to social dominance that humans are sensitive to within the first few years of life.Indeed, if young human infants have core knowledge of social relationships, as some have argued (13, 25), along with the capability to track the numerical size of small groups (26), it is possible that infants may be able to draw on both capacities to support inferences about the social dominance relationship between groups that differ in numerical size. If infants infer that individuals from larger groups are more dominant than individuals from smaller groups, this would demonstrate that infants’ understanding of social dominance can extend beyond the direct relationship between two competing individuals. Specifically, such a finding may shed light on whether infants already have an understanding of how social alliances operate—namely, that group members may help their own during a conflict, which confers a benefit to having more alliance members in close proximity during a conflict (10).Here, we explored whether infants can infer the dominance relationship between two agents from groups that differ in numerical size by modifying the methodology designed by Thomsen et al. (13). In our study, infants were first introduced to two groups that differed in numerical size (but equated for total surface area) and color. Next, infants were familiarized to an agent from each group independently achieving their goal of crossing a platform. When both of these agents attempted to cross the platform simultaneously, they bumped into one another. Therefore, the only way an agent could continue along their goal path was if one agent yielded to the other by moving out of the way.In study 1, we investigated whether 9- to 12-mo-old infants use numerical group size as a cue to social dominance. In study 2, we examined whether 6- to 9-mo-old infants (who have not yet been shown to represent social dominance relationships between individuals) would also be sensitive to the cue of numerical group size. Infants in studies 1 and 2 viewed the same sequence of events.     

Increasing diversity of Human Immunodeficiency Virus type 1 subtypes circulating in Australia

Characterization of HIV subtypes can provide a more comprehensive understanding of the epidemic within a distinct region, and when combined with notification data, may also be helpful in enhancing current HIV prevention strategies. In this study, we characterized 1056 HIV-positive individuals (948 males and 108 females) living in Victoria and whose infection was detected for the first time between 2005 and 2010 inclusive. HIV-1 strains were subtyped based on pol gene sequence. Phylogenetic analysis was performed on all non-B subtype sequences identified. Of the 1056 sequences analyzed, 825 were subtype B and 231 were non-B. Overall 6 HIV-1 subtypes, 6 circulating recombinant forms (CRFs), and 12 unique recombinant forms (URFs) were identified. Regardless of gender, the majority of individuals were infected with a subtype B virus (78%). Subtype B was dominant in males (n=806, 85%). In contrast, the majority of females were infected with non-B subtypes (n=89, 82%), in particular subtype C (n=48, 45%). Phylogenetic analysis of the non-B subtypes revealed that the majority of clustering, and thereby transmission, occurred with CRF01_AE strains. Despite the relatively high numbers identified in females there was very little clustering of subtype C viruses. Subtypes C and A1 both historically associated with heterosexual transmission, and CRF01_AE often associated with IVDU, were also associated with transmission within the MSM population, demonstrating the potential for non-B subtypes to expand into the MSM population. The observation of increasing numbers of females and heterosexual males infected with non-subtype B viruses, the majority imported through migration and travel to countries where there is a high prevalence of HIV, suggests a targeted public health message may be required to prevent further increases within these two groups.     

Weight Recidivism Post-Bariatric Surgery: A Systematic Review

Obesity is considered a worldwide health problem of epidemic proportions. Bariatric surgery remains the most effective treatment for patients with severe obesity, resulting in improved obesity-related co-morbidities and increased overall life expectancy. However, weight recidivism has been observed in a subset of patients post-bariatric surgery. Weight recidivism has significant medical, societal and economic ramifications. Unfortunately, there is a very limited understanding of how to predict which bariatric surgical patients are more likely to regain weight following surgery and how to appropriately treat patients who have regained weight. The objective of this paper is to systematically review the existing literature to assess the incidence and causative factors associated with weight regain following bariatric surgery. An electronic literature search was performed of the Medline, Embase and Cochrane library databases along with the PubMed US national library from January 1950 to December 2012 to identify relevant articles. Following an initial screen of 2,204 titles, 1,437 abstracts were reviewed and 1,421 met exclusion criteria. Sixteen studies were included in this analysis: seven case series, five surveys and four non-randomized controlled trials, with a total of 4,864 patients for analysis. Weight regain in these patients appeared to be multi-factorial and overlapping. Aetiologies were categorized as patient specific (psychiatric, physical inactivity, endocrinopathies/metabolic and dietary non-compliance) and operation specific. Weight regain following bariatric surgery varies according to duration of follow-up and the bariatric surgical procedure performed. The underlying causes leading to weight regain are multi-factorial and related to patient- and procedure-specific factors. Addressing post-surgical weight regain requires a systematic approach to patient assessment focusing on contributory dietary, psychologic, medical and surgical factors.     

Short‐term environmental enrichment,in the absence of exercise,improves memory,and increases NGF concentration,early neuronal survival,and synaptogenesis in the dentate gyrus in a time‐dependent manner

Environmental manipulations can enhance neuroplasticity in the brain, with enrichment‐induced cognitive improvements being linked to increased expression of growth factors, such as neurotrophins, and enhanced hippocampal neurogenesis. There is, however, a great deal of variation in environmental enrichment protocols used in the literature, making it difficult to assess the role of particular aspects of enrichment upon memory and the underlying associated mechanisms. This study sought to evaluate the efficacy of environmental enrichment, in the absence of exercise, as a cognitive enhancer and assess the role of Nerve Growth Factor (NGF), neurogenesis and synaptogenesis in this process. We report that rats housed in an enriched environment for 3 and 6 weeks (wk) displayed improved recognition memory, while rats enriched for 6 wk also displayed improved spatial and working memory. Neurochemical analyses revealed significant increases in NGF concentration and subgranular progenitor cell survival (as measured by BrdU+ nuclei) in the dentate gyrus of rats enriched for 6 wk, suggesting that these cellular changes may mediate the enrichment‐induced memory improvements. Further analysis revealed a significant positive correlation between recognition task performance and BrdU+ nuclei. In addition, rats enriched for 6 wk showed a significant increase in expression of synaptophysin and synapsin I in the dentate gyrus, indicating that environmental enrichment can increase synaptogenesis. These data indicate a time‐dependent cognitive‐enhancing effect of environmental enrichment that is independent of physical activity. These data also support a role for increased concentration of NGF in dentate gyrus, synaptogenesis, and neurogenesis in mediating this effect. © 2013 Wiley Periodicals, Inc.