Evolocumab in paediatric heterozygous familial hypercholesterolaemia: cognitive function during 80 weeks of open-label extension treatment

AIMS

PCSK9 inhibition intensively lowers low density lipoprotein cholesterol and is well tolerated in adults and paediatric patients with familial hypercholesterolaemia (FH). HAUSER-RCT showed that 24 weeks of treatment with evolocumab in paediatric patients did not affect cognitive function. This study determined the effects of 80 additional weeks of evolocumab treatment on cognitive function in paediatric patients with heterozygous FH.

METHODS AND RESULTS

HAUSER-OLE was an 80-week open-label extension of HAUSER-RCT, a randomized, double-blind, 24-week trial evaluating the efficacy and safety of evolocumab in paediatric patients (ages 10-17 years) with FH. During the OLE, all patients received monthly 420 mg subcutaneous evolocumab injections. Tests of psychomotor function, attention, visual learning, and executive function were administered at baseline and Weeks 24 and 80 of the OLE. Changes over time were analysed descriptively and using analysis of covariance. Cohen's d statistic was used to evaluate the magnitude of treatment effects. Analysis of covariance results indicated no decrease in performance across visits during 80 weeks of evolocumab treatment for Groton Maze Learning, One Card Learning accuracy, Identification speed, or Detection speed (all P > 0.05). Performance on all tasks was similar for those who received placebo or evolocumab in the RCT (all P > 0.05). For all tests, the least square mean differences between patients who received placebo vs. evolocumab in the parent study were trivial (all Cohen's d magnitude < 0.2).

CONCLUSION

In paediatric patients with FH, 80 weeks of open-label evolocumab treatment had no negative impact on cognitive function.

REGISTRATION

ClinicalTrials.gov identifier: NCT02624869.

Incorporating Risk Stratification Into the Practice of Pediatric Preventive Cardiology

Atherosclerosis in its earliest stages is associated with the same traditional cardiovascular disease (CVD) risk factors as are associated with manifest CVD events in adulthood. Clustering of risk factors is associated with exponential increases in atherosclerotic burden from a young age. Some medical conditions and risk behaviours occurring in children can either increase the likelihood of higher levels of risk factors (such as chronic kidney disease) or the presence of risk factor clustering (such as obesity and cardiometabolic syndrome) or are associated with acquired coronary artery pathology (such as Kawasaki disease). This creates a milieu for-or increases the impact of-accelerated atherosclerosis that, in turn, increases the likelihood of premature CVD. This review highlights the importance of considering the total risk factor and risk-condition profile of pediatric patients. An algorithm is provided for stratifying patients into high-, moderate-, and at-risk categories, and practical examples are provided as to how the evaluation and management of 1 risk factor or risk condition might need to be intensified in the context of additional risk factors or risk conditions. For example, for treatment of an adolescent with familial hypercholesterolemia, the target low-density lipoprotein cholesterol level might be lowered by the concomitant presence of low high-density lipoprotein cholesterol or elevated lipoprotein(a) levels. As awareness of cardiovascular risk and atherosclerosis in pediatric patients increases, new at-risk conditions that warrant consideration are emerging. The identification and management of high-risk individuals is an important part of the overall practice of pediatric preventive cardiology.

Alterations in cellular energy metabolism associated with the antiproliferative effects of the ATM inhibitor KU-55933 and with metformin

KU-55933 is a specific inhibitor of the kinase activity of the protein encoded by Ataxia telangiectasia mutated (ATM), an important tumor suppressor gene with key roles in DNA repair. Unexpectedly for an inhibitor of a tumor suppressor gene, KU-55933 reduces proliferation. In view of prior preliminary evidence suggesting defective mitochondrial function in cells of patients with Ataxia Telangiectasia (AT), we examined energy metabolism of cells treated with KU-55933. The compound increased AMPK activation, glucose uptake and lactate production while reducing mitochondrial membrane potential and coupled respiration. The stimulation of glycolysis by KU-55933 did not fully compensate for the reduction in mitochondrial functions, leading to decreased cellular ATP levels and energy stress. These actions are similar to those previously described for the biguanide metformin, a partial inhibitor of respiratory complex I. Both compounds decreased mitochondrial coupled respiration and reduced cellular concentrations of fumarate, malate, citrate, and alpha-ketogluterate. Succinate levels were increased by KU-55933 levels and decreased by metformin, indicating that the effects of ATM inhibition and metformin are not identical. These observations suggest a role for ATM in mitochondrial function and show that both KU-55933 and metformin perturb the TCA cycle as well as oxidative phosphorylation.

Influence of husbandry and control measures on porcine circovirus type 2 (PCV-2) dynamics within a farrow-to-finish pig farm: a modelling approach

We assessed, using a modelling approach, the influence of several management practices within a farrow-to-finish farm on the age of PCV-2 infection. The impact of PCV-2 vaccination with different vaccination schemes on infection dynamics, was also tested. A stochastic individual-based model describing the population dynamics in a typical French farrow-to-finish pig farm was built and coupled with an epidemiological model of PCV-2 infection. The parameters of the infectious model were mainly obtained from previous transmission experiments. Results were subjected to a survival analysis of time-to-infection. For each comparison, the reference situation was no vaccination followed by random mixing of piglets after birth and after weaning. The risk of early infection was significantly reduced when mixing of piglets was reduced at different stages (avoiding cross-fostering and grouping piglets by litters in small pens after weaning, hazard ratio (HR)=0.52 [0.46; 0.59]). Sow-targeted vaccination delayed the infectious process until the waning of passive immunity and piglet-targeted vaccination considerably decreased the force of infection leading to a dramatic decrease of the total number of infections (HR=0.44 [0.37; 0.54]). The effect was even more pronounced when strict management measures were applied (HR=0.24 [0.19; 0.31]). Changing from a low (3%) prevalence of PCV-2-infected semen to a higher one (18%) significantly increased the risk of early infections (HR=1.36 [1.2; 1.53]), whereas reducing replacement rate or changing sow housing from individual crates to group housing had a limited impact on PCV-2 dynamics.

How could host discrimination abilities influence the structure of a parasitoid community?

Three related Aphidius parasitoid species share the same host, the grain aphid Sitobion avenae. Among this parasitoid community, Aphidius rhopalosiphi is the most abundant species in the field. Both the interspecific host discrimination of A. rhopalosiphi towards hosts parasitized by the two other species (i.e. A. avenae and A. ervi) and the interspecific host discrimination of the two other species towards hosts parasitized by A. rhopalosiphi were studied here. Results showed that females of A. rhopalosiphi and A. avenae both discriminated between unparasitized hosts and hosts parasitized by the other species. This discrimination occurred only after ovipositor insertion, suggesting the perception of an internal marker of parasitism. Likewise, females of A. rhopalosiphi and A. ervi were able to discriminate between unparasitized hosts and hosts parasitized by the other species. However, in this combination of species, recognition of parasitized hosts occurred before ovipositor insertion, through an antennal perception, suggesting the presence an external cue indicating parasitism. Hence, interspecific host discrimination in the three Aphidius species is based on internal or external cues, which are used either alone or together. Our results showed that the cues used for interspecific host discrimination depend on the specific identity of the interaction. These differences seemed strongly linked to the way the different species respond to defensive behaviours of their aphid hosts. Results are discussed in the context of optimal foraging and possible consequences for community structure.

Modelling the time-dependent transmission rate for porcine circovirus type 2 (PCV2) in pigs using data from serial transmission experiments

Six successive transmission trials were carried out from 4 to 39 days post inoculation (DPI) to determine the features of the infectious period for PCV2-infected pigs. The infectiousness of inoculated pigs, assessed from the frequency of occurrence of infected pigs in susceptible groups in each contact trial, increased from 4 to 18 DPI (0, 7 and 8 infected pigs at 4, 11 and 18 DPI, respectively) and then decreased slowly until 39 days post infection (4, 2 and 1 pigs infected at 25, 32 and 39 DPI, respectively). The estimated time-dependent infectiousness was fitted to three unimodal function shapes (gamma, Weibull and lognormal) for comparison. The absence of infected pigs at 4 DPI revealed a latency period between 4 and 10 DPI. A sensitivity analysis was performed to test whether the parametric shape of the transmission function influenced the estimations. The estimated time-dependent transmission rate was implemented in a deterministic SEIR model and validated by comparing the model prediction with external data. The lognormal-like function shape evidenced the best quality of fit, leading to a latency period of 8 days, an estimated basic reproduction ratio of 5.9 [1.8,10.1] and a mean disease generation time of 18.4 days [18.2, 18.5].

A branching process, its application in biology: influence of demographic parameters on the social structure in mammal groups

Branching processes are widely used in biology. This theoretical tool is used in cell dynamics, epidemics and population dynamics. In population dynamics, branching processes are mainly used to access extinction probabilities of populations, groups or families, with the Galton-Watson branching process. Many mammal species live in socially-structured groups, and the smallest units of these groups are lineages (or families) of kin-related individuals. In many primate species, these lineages are matrilines, as females remain in their natal groups most of the time, whereas males generally disperse. Lineage parameters, such as numbers of matrilines, size of each matriline and average degree of relatedness, could strongly influence the genetic composition of groups. Evidence indicates that division along matrilines could induce substantial differentiation among fission groups. Here, we develop a novel mathematical model based on the branching process theory describing demographic dynamics of groups. The main result of this model is an explicit analytical expression of the joint distribution of numbers of lineages and sizes of socially-structured groups. We investigated the influence of parameters such as natality and mortality on the outcome of the process, including extinction probability. Finally, we discuss this theoretical result with respect to biological significance.

The moving Dynamic Random Dot Stereosize test: development, age norms, and comparison with the Frisby, Randot, and Stereo Smile tests

PURPOSE

To determine the response of infants and children to the Moving Dynamic Random Dot Stereosize (MDRS) test and to collect cross-sectional age-related data.

METHODS

Sixty visually normal individuals were divided into four age groups: 0.5-<2, 2-<5, 5-<8, and 8-<20 years. Stereopsis was measured with the MDRS test on two occasions, plus the Frisby, Randot, or Stereo Smile tests, as was age appropriate.

RESULTS

All children aged >2 years and 80% of the children between ages 6 months and 2 years were able to perform the MDRS test on at least one occasion. Sixty percent of the 6-month to 2-year-old children were able to perform the Stereo Smile test on both occasions. Performance on the MDRS test improved with age up to 9 years. Improvement on the Frisby and Randot tests was seen in children aged up to 7 years. Mean and 95% confidence interval ranges for each test are given.

CONCLUSION

This study gives evidence that aspects of the visual system are not fully mature until age 7-9 years. The MDRS test is a visually demanding but cognitively simple test that shows potential for detecting visual anomalies in young children.

Superparasitism limitation in an aphid parasitoid: cornicle secretion avoidance and host discrimination ability

Superparasitism avoidance by the endoparasitoid Aphidius rhopalosiphi De Stefani Perez on the grain aphid, Sitobion avenae was studied. Experiments were carried out in which aphids were exposed to two consecutive attacks by parasitoids. Results showed that superparasitism avoidance in A. rhopalosiphi was mediated by two successive stimuli whose effectiveness depended on the time interval between attacks. For short time intervals (<16 h), host rejections were mainly associated with the presence of dried cornicle secretion on the host's body which was exuded during the first attack. The repellency of this secretion declined with the time interval between attacks, becoming ineffective 2 days after the first parasitization, and allowed females to reject up to 30% of parasitized hosts. For longer time intervals (>/=16 h), host rejection behavior was a response of parasitoid females to internal changes in host quality associated with parasite development. This response gradually increased with an increase in time interval, reaching no more than 60%, 96 h after initial parasitization. This host discrimination ability did not allow females to distinguish between hosts parasitized by themselves or by conspecifics. Consequently, these findings suggest that superparasitism is a common event in A. rhopalosiphi and especially on recently parasitized hosts.

Reproductive mode and population genetic structure of the cereal aphid Sitobion avenae studied using phenotypic and microsatellite markers

As French populations of the aphid Sitobion avenae exhibit a range of reproductive modes, this species provides a good opportunity for studying the evolution of breeding system variation. The present analysis combined ecological and genetic investigations into the spatial distribution of variation in reproductive mode. Reproductive mode was characterized in 277 lineages of S. avenae from France, and these aphids were scored for five microsatellite loci. The analyses revealed strong geographical partitioning of breeding systems, with obligate asexuals mostly restricted to the south of France, while lineages producing sexual forms were more common in the north. Contrary to what might be anticipated for organisms with frequent parthenogenesis, there was substantial genic and genotypic diversity, even in the obligately asexual lineages. More than 120 different genotypes were detected among the 277 aphid lineages, with an average of 5.9 alleles per locus (range four to 16) and heterozygosity of 56.7%. As with previous studies of allozyme variation in aphids, most loci showed heterozygote deficits, and disequilibrium was common among allelic variants at different loci, even after removal of replicate copies of genotypes that might have been derived through clonal reproduction. Our results suggest that selection is important in structuring reproductive systems and genetic variation in French S. avenae. Canonical correspondence analysis was employed to examine the associations between genotypic and phenotypic variables, enabling the identification of alleles correlated with life-history traits.

Coexistence between cyclical parthenogens, obligate parthenogens, and intermediates in a fluctuating environment

We evaluate the cost of sex in cyclical parthenogens coexisting with obligate parthenogens that produce a few sexuals, a situation found in numerous species. In aphids and cladocera, sex is generally the only way to produce a resistant form; this gives a potential ecological advantage to sex. We focus on the selective factor constituted by variations of the environment, that may be alternatively advantageous to cyclical parthenogens (cold winters in aphids, drought in daphnia) or to obligate parthenogens. Our calculations show that the production of a few sexuals by lineages that are essentially obligate parthenogens has a critical effect on the balance between the different life-cycles, especially when this production is limited to males. This male production by intermediates confers additional fitness to obligate parthenogenesis genes and then sharply increases the cost of sex. Copyright 1998 Academic Press

Effect of cold acclimation on vascularization of ears, heart, liver and muscles of white rats

The degree of vascularization of different tissues of rats killed with ether after a 4-week acclimation period to 30°C or 6°C was estimated by counting on benzidine stained cross-sections, capillaries in heart and leg muscles (soleus, gastrocnemius, plantaris), sinusoids in liver and all blood vessels in ears. Short exposure to cold (2 hr.) of the 30°C acclimated rats had no effect on the vascularization of any of the organs studied. Cold acclimation had no effect on number of capillaries in the heart and sinusoids in the liver, but in the ears it produced a 12-fold increase in number of blood vessels. In the plantaris and the red fiber regions of the gastrocnemius but not in the white fiber region of the latter, there was an absolute increase in the number of capillaries/mm2. In the soleus and the two heads of gastrocnemius, there were densely vascularized subregions which were on the average approximately 50% larger after cold acclimation. The increases in the number of opened capillaries observed in the ears and the leg muscles are interpreted as indicating a higher metabolism, and possibly an increased chemical thermogenesis in the red fiber muscles.