Impact of infancy duration on adult size in 22 subsistence-based societies

Aim: Humans evolved to withstand harsh environments by adaptively decreasing their body size. Thus, adaptation to a hostile environment defers the infancy‐childhood transition age (ICT), culminating in short stature. In natural‐fertility human societies, this transition is associated with weaning from breastfeeding and the mother’s new pregnancy. We therefore used the interbirth interval (IBI) as a surrogate for the ICT. Methods: We hypothesized that long IBI will be associated with smaller body size. The sample used is 22 subsistence‐based societies of foragers, horticulturalists and pastorals from Africa, South America, Australia and Southeast Asia. Results: The IBI correlated negatively with the average adult bodyweight but not height. After correction for ‘pubertal spurt takeoff’ and ‘weight at age 5’, the IBI explains 81% of ‘average adult weight’ variability. Conclusions: This inter‐population study confirms that body weight is adaptively smaller in hostile environments and suggests that the selected trait for this adaptation is the ICT age.     

Event-related slow-wave activity in two subtypes of attention-deficit/hyperactivity disorder.

OBJECTIVE: Previous time-frequency studies have indicated that event-related low-frequency activity has important effects on component topography and developmental effects in auditory event-related potentials (ERPs) of children and adolescents. This study investigated the influence of event-related slow-wave (SW) (0.01-2 Hz) activity in the group differences seen between children with and without attention-deficit/hyperactivity disorder (AD/HD) of different subtypes. METHODS: Time-frequency analysis techniques were applied to auditory ERP data derived from children with AD/HD predominantly inattentive type (n = 30), AD/HD combined type (n = 30) and age-matched control subjects (n = 30). RESULTS: Event-related early frontal negative and late posterior positive SW components were reduced in the AD/HD combined type group, but not AD/HD inattentive type group, relative to controls. The RESIDUAL ERPs, which represented event-related 2-12 Hz activity, showed clinical vs. control group differences in components that were similar in both AD/HD subtype groups. CONCLUSIONS: The time-frequency results showed that event-related SW (0.1-2 Hz) activity contributes importantly to group differences between AD/HD and control children, and the pattern of group differences from controls for each of the AD/HD subtype groups, which are evident in raw ERPs. These results emphasise both the clinical and developmental importance of this form of analysis. SIGNIFICANCE: This novel approach revealed additional specific information about stimulus processing and regional inhibition/activation in two AD/HD subtypes, relative to control subjects.     

A risk of breast cancer in women - carriers of constitutional <Emphasis Type="Italic">CHEK2</Emphasis> gene mutations,originating from the North - Central Poland

Background

Germline mutations of the CHEK2 gene have been reported to be associated with breast cancer. In this study, we analyzed the association of CHEK2 mutations with the risk of development of breast cancer in women of North-Central Poland.

Methods

420 women with breast cancer and 435 controls were tested for three protein truncating (IVS2 + 1G > A, 1100delC, del5395) and one missense (I157T) CHEK2 mutation. IVS2 + 1G > A and I157T mutations were identified by RFLP-PCR, 1100delC variant was analyzed using an ASO-PCR and del5395 mutation by multiplex-PCR. The statistical tests: the odds ratio (OR) and Fisher’s exact test were used.

Results

In 33 out of 420 (7.9%) women consecutively diagnosed with breast cancer, we detected one of four analyzed CHEK2 mutations: I157T, 1100delC, IVS2 + 1G > A or del5395. Together they were not associated with the increased risk of breast cancer (North-Central control group: OR = 1.6, p = 0.124; the general Polish population: OR = 1.4, p = 0.109). This association was only seen for IVS2 + 1G > A mutation (OR = 3.0; p = 0.039). One of the three truncating CHEK2 mutations (IVS2 + 1G > A, 1100delC, del5395) was present in 9 of 420 women diagnosed with breast cancer (2.1%) and in 4 of 121 women (3.3%) with a history of breast cancer in a first- and/or second- degree relatives. Together they were associated with the increased risk of disease in these groups, compared to the general Polish population (OR = 2.1, p = 0.053 and OR = 3.2; p = 0.044, respectively). I157T mutation was detected in 25 of 420 women diagnosed with breast cancer (6.0%) and in 8 of 121 women (6.6%) with a history of breast cancer in first- and/or second- degree relatives. The prevalance of I157T mutation was 4.1% (18/435) in North-Central control group and 4.8% (265/5.496) in the general Polish population. However it was not associated with an increased risk of breast cancer.

Conclusion

Obtained results suggest that CHEK2 mutations could potentially contribute to the susceptibility to breast cancer. The germline mutations of CHEK2, especially the truncating ones confer low-penetrance breast cancer predisposition that contribute significantly to familial clustering of breast cancer at the population level.     

Divergent effects of age on performance in spatial associative learning and real idiothetic memory in humans

This study focuses on age-related differences concerning two kinds of spatial memory assessed by: (1) Paired Associates Learning (PAL) test from the CANTAB and (2) a test of Real Idiothetic Memory (RIM) using real-life settings. Despite a clear age-related drop in PAL that is reported in existing studies, age-related differences in idiothetic navigation still remain unclear. In our study we tested 80 healthy volunteers classified according to their age into two groups, i.e. young (aged from 20 to 29 years of life; n=40; 20M/20F) and elderly (from 64 to 77 years; n=40; 20M/20F) healthy volunteers. They were asked in the PAL test to remember the spatial location of visual patterns presented on a computer screen, and in the RIM test to walk on the arena in darkness in order to find a cue place and then to return to the start/exit point. A white noise was switched on at entering the cue place and switched off at leaving this place. Elderly subjects indicated poorer performance than their younger counterparts on the PAL test, as evidenced by all tested outcome measures. In contrast, for the RIM test no clear age effect was evidenced. In both tests no gender effect was observed. A dissociation in age-related changes for these two tests indicates that visuo-spatial associative learning and idiothetic navigation may have different cognitive control which is probably rooted in an interplay of different brain structures.     

Effect of Secondary Carbon Nanofillers on the Electrical,Thermal, and Mechanical Properties of Conductive Hybrid Composites Based on Epoxy Resin and Graphite

In this work, we present a comparative study of the impact of secondary carbon nanofillers on the electrical and thermal conductivity, thermal stability, and mechanical properties of hybrid conductive polymer composites (CPC) based on high loadings of synthetic graphite and epoxy resin. Two different carbon nanofillers were chosen for the investigation—low-cost multi-layered graphene nanoplatelets (GN) and carbon black (CB), which were aimed at improving the overall performance of composites. The samples were obtained by a simple, inexpensive, and effective compression molding technique, and were investigated by the means of, i.a., scanning electron microscopy, Raman spectroscopy, electrical conductivity measurements, laser flash analysis, and thermogravimetry. The tests performed revealed that, due to the exceptional electronic transport properties of GN, its relatively low specific surface area, good aspect ratio, and nanometric sizes of particles, a notable improvement in the overall characteristics of the composites (best results for 4 wt % of GN; σ = 266.7 S cm⁻¹; λ = 40.6 W mK⁻¹; fl. strength = 40.1 MPa). In turn, the addition of CB resulted in a limited improvement in mechanical properties, and a deterioration in electrical and thermal properties, mainly due to the too high specific surface area of this nanofiller. The results obtained were compared with US Department of Energy recommendations regarding properties of materials for bipolar plates in fuel cells. As shown, the materials developed significantly exceed the recommended values of the majority of the most important parameters, indicating high potential application of the composites obtained.     

Left atrial and left atrial appendage systolic function in patients with post-myocardial distal blocks

Introduction

The study aimed to evaluate function of the left atrium (LA) and of the left atrial appendage (LAA) after myocardial infarction (MI) complicated by intracardiac conduction disturbances.

Material and methods

The study comprised 59 patients with persistent post-myocardial distal blocks, who were allocated to one of the three following subgroups: study group I – 20 patients with left bundle branch block (LBBB); study group II – 20 patients with right bundle branch block (RBBB), and study group III –19 pts with left anterior hemiblock (LAHB). The control groups included patients with MI in their history and no BBBs (19 pts – group IV) and clinically healthy people (16 patients – group V). The parameters of LA and LAA systolic function were determined by means of transthoracic (TTE) and transoesophageal echocardiography (TOE).

Results

We showed that patients who experienced myocardial infarction not complicated with conduction disturbances expressed compensatory LA systolic function enhancement. In patients with post-myocardial RBBB and LAHB significant enhancement of LA systolic function was observed as well but it was expressed to a lesser degree. There was also a tendency towards deterioration of LA systolic function in patients with post-myocardial LBBB. LBBB did not affect LAA systolic function negatively.

Conclusions

Parameters of LAA systolic function showed its enhancement in all patients after myocardial infarction irrespective of whether it was complicated by conduction disturbances.Key words: left atrium, left atrial appendage, echocardiography, distal blocks