Age-dependent Strategy Research Articles

Gordon Holmes Syndrome Model Mice Exhibit Alterations in Microglia, Age, and Sex-Specific Disruptions in Cognitive and Proprioceptive Function.

Gordon Holmes syndrome (GHS) is a neurological disorder associated with neuroendocrine, cognitive, and motor impairments with corresponding neurodegeneration. Mutations in the E3 ubiquitin ligase RNF216 are strongly linked to GHS. Previous studies show that deletion of Rnf216 in mice led to sex-specific neuroendocrine dysfunction due to disruptions in the hypothalamic-pituitary-gonadal axis. To address RNF216 action in cognitive and motor functions, we tested Rnf216 knock-out (KO) mice in a battery of motor and learning tasks for a duration of 1 year. Although male and female KO mice did not demonstrate prominent motor phenotypes, KO females displayed abnormal limb clasping. KO mice also showed age-dependent strategy and associative learning impairments with sex-dependent alterations of microglia in the hippocampus and cortex. Additionally, KO males but not females had more negative resting membrane potentials in the CA1 hippocampus without any changes in miniature excitatory postsynaptic current (mEPSC) frequencies or amplitudes. Our findings show that constitutive deletion of Rnf216 alters microglia and neuronal excitability, which may provide insights into the etiology of sex-specific impairments in GHS.

Electroencephalographic markers of brain development during sevoflurane anaesthesia in children up to 3 years old

BackgroundGeneral anaesthetics generate spatially defined brain oscillations in the EEG that relate fundamentally to neural-circuit architecture. Few studies detailing the neural-circuit activity of general anaesthesia in children have been described. The study aim was to identify age-related changes in EEG characteristics that mirror different stages of early human brain development during sevoflurane anaesthesia. MethodsMultichannel EEG recordings were performed in 91 children aged 0–3 yr undergoing elective surgery. We mapped spatial power and coherence over the frontal, parietal, temporal, and occipital cortices during maintenance anaesthesia. ResultsDuring sevoflurane exposure: (i) slow–delta (0.1–4 Hz) oscillations were present in all ages, (ii) theta (4–8 Hz) and alpha (8–12 Hz) oscillations emerge by ∼4 months, (iii) alpha oscillations increased in power from 4 to 10 months, (iv) frontal alpha-oscillation predominance emerged at ∼6 months, (v) frontal slow oscillations were coherent from birth until 6 months, and (vi) frontal alpha oscillations became coherent ∼10 months and persisted in older ages. ConclusionsKey developmental milestones in the maturation of the thalamo-cortical circuitry likely generate changes in EEG patterns in infants undergoing sevoflurane general anaesthesia. Characterisation of anaesthesia-induced EEG oscillations in children demonstrates the importance of developing age-dependent strategies to monitor properly the brain states of children receiving general anaesthesia. These data have the potential to guide future studies investigating neurodevelopmental pathologies involving altered excitatory–inhibitory balance, such as epilepsy or Rett syndrome.

Age-dependent strategies related to lionfish activities in the Mexican Caribbean

Lionfish are successful invasive predators in the Caribbean region and inhabit a large range of habitats. Our study in the Caribbean has focused on the relationships between the biological characteristics of lionfish particularly their size, their activities and use of those different habitats. In this study, we observed a high number of lionfish individuals, focusing on the behavioural activities and biological traits in relation to different habitats and environmental characteristics. We monitored 793 individuals, recording their activities, biological traits, and habitat characteristics. Our results report that lionfish are not solitary, but frequently form groups for many activities. We provide evidence of differences between lionfish habitat use according to activity, and the size of individual fish. Considering the size is correlated with age, coral reefs appear to be the preferred habitat of older individuals, whereas the youngest lionfish use a diversity of habitats, ranging from mangroves to coral reefs. In addition, this study suggests that predation of lionfish is age-dependent strategy, and depends on time and the tone of the environment. Lionfish do not only use the head-down posture to catch prey but also horizontal and head-up postures. The youngest lionfish hunt mainly in dark areas and during the night while the older fish were observed hunting mostly during the day and in clear areas. These new aspects of lionfish ecology and behaviour are discussed in light of their invasive success.

Optimizing strategies for population-based chlamydia infection screening among young women: an age-structured system dynamics approach.

BackgroundChlamydia infection (CT) is one of the most commonly reported sexually transmitted diseases. It is often referred to as a “silent” disease with the majority of infected people having no symptoms. Without early detection, it can progress to serious reproductive and other health problems. Economical identification of asymptomatically infected is a key public health challenge. Increasing evidence suggests that CT infection risk varies over the range of adolescence. Hence, age-dependent screening strategies with more frequent testing for certain age groups of higher risk may be cost-saving in controlling the disease.MethodsWe study the optimization of age-dependent screening strategies for population-based chlamydia infection screening among young women. We develop an age-structured compartment model for CT natural progress, screening, and treatment. We apply parameter optimization on the resultant PDE-based system dynamical models with the objective of minimizing the total care spending, including screening and treatment costs during the program period and anticipated costs of treating the sequelae afterwards). For ease of practical implementation, we also search for the best screening initiation age for strategies with a constant screening frequency.ResultsThe optimal age-dependent strategies identified outperform the current CDC recommendations both in terms of total care spending and disease prevalence at the termination of the program. For example, the age-dependent strategy that allows monthly screening rate changes can save about 5 % of the total spending. Our results suggest early initiation of CT screening is likely beneficial to the cost saving and prevalence reduction. Finally, our results imply that the strategy design may not be sensitive to accurate quantification of the age-specific CT infection risk if screening initiation age and screening rate are the only decisions to make.ConclusionsOur research demonstrates the potential economic benefit of age-dependent screening strategy design for population-based screening programs. It also showcases the applicability of age-structured system dynamical modeling to infectious disease control with increasing evidence on the age differences in infection risk. The research can be further improved with consideration of the difference between first-time infection and reinfection, as well as population heterogeneity in sexual partnership.

Invasive species control: Incorporating demographic data and seed dispersal into a management model for Rhododendron ponticum

Rhododendron ponticum is a serious invasive alien plant in the British Isles and is of significant conservation and economic concern. Here, we integrate information on both the demographics and spatial dynamics of this species within an individual-based, spatially-explicit model and investigate the effectiveness of different control strategies. Importantly, we simulate seed movement and dispersal using a mechanistic seed dispersal model. We investigate the effectiveness of initiating control at the edge versus the core of the infestation, with and without returning each year to remove seedlings. We compare these results to an age-dependent strategy whereby the oldest plants are removed each year. Age-dependent control, in which the oldest plants were removed first, was the most effective strategy investigated, both in terms of the probability of successful eradication and the number of years taken to control. We demonstrate that this is because the older (and taller) plants towards the core produce more seeds that, on average, travel further. Indeed, our results suggest that the expansion of the invading front is actually driven as much by seeds that disperse long distances from these larger plants as by the seed rain from recently matured plants located much closer to the front. Finally, we investigate the potential use of ‘quarantine lines’ — corridors of unsuitable habitat that are sufficiently wide to contain an infestation, preventing spread to vulnerable areas. This study has provided generic insights into best practice for management based on the current understanding of the biology and ecology of this pernicious, invasive plant.

Risk acceptance and maintenance optimization of aging civil engineering infrastructures

The renewal model for cost-benefit optimization including maintenance is presented. Three types of maintenance strategies are proposed, i.e. age-dependent maintenance, block maintenance and maintenance by inspection and (perfect) repair. Then, new concepts for risk acceptability based on the life quality index philosophy are introduced. It is demonstrated that in limiting the failure rate three concepts can be used, the first addressing the maximum failure rate, a second using a time-average and the third an asymptotic value which may be proposed for practical use. All concepts, however, require computation of the exact failure rate (renewal intensity) or, at least, the asymptotic failure rate. A suitable asymptotic failure rate related to all corrective renewals after failure is given. A numerical example is given showing that the inspection/repair maintenance strategy is more cost-effective than the age-dependent strategy.