Relatively lower body mass index is associated with an excess of severe truncal asymmetry in healthy adolescents: Do white adipose tissue, leptin, hypothalamus and sympathetic nervous system influence truncal growth asymmetry?

<p>Abstract</p> <p>Background</p> <p>In healthy adolescents normal back shape asymmetry, here termed truncal asymmetry (TA), is evaluated by higher and lower subsets of BMI. The study was initiated after research on girls with adolescent idiopathic scoliosis (AIS) showed that higher and lower BMI subsets discriminated patterns of skeletal maturation and asymmetry unexplained by existing theories of pathogenesis leading to a new interpretation which has therapeutic implications <it>(double neuro-osseous theory)</it>.</p> <p>Methods</p> <p>5953 adolescents age 11–17 years (boys 2939, girls 3014) were examined in a school screening program in two standard positions, standing forward bending (FB) and sitting FB. The sitting FB position is thought to reveal intrinsic TA free from back humps induced by any leg-length inequality. TA was measured in both positions using a Pruijs scoliometer as angle of trunk inclinations (ATIs) across the back at each of three spinal regions, thoracic, thoracolumbar and lumbar. Abnormality of ATIs was defined as being outside 2 standard deviations for each age group, gender, position and spinal region, and termed <it>severe </it>TA.</p> <p>Results</p> <p>In the sitting FB position after correcting for age,<it>relatively lower BMIs </it>are statistically associated with a greater number of severe TAs than with relatively higher BMIs in both girls (thoracolumbar region) and boys (thoracolumbar and lumbar regions).</p> <p>The relative frequency of severe TAs is significantly higher in girls than boys for each of the right thoracic (56.76%) and thoracolumbar (58.82%) regions (p = 0.006, 0.006, respectively). After correcting for age, smaller BMIs are associated with more <it>severe TAs </it>in boys and girls.</p> <p>Discussion</p> <p>BMI is a surrogate measure for body fat and circulating leptin levels. The finding that girls with relatively lower BMI have significantly later menarche, and a significant excess of TAs, suggests a relation to energy homeostasis through the hypothalamus. The hypothesis we suggest for the pathogenesis of severe TA in girls and boys has the same mechanism as that proposed recently for AIS girls, namely: severe TAs are initiated by a <it>genetically-determined selectively </it>increased hypothalamic sensitivity (up-regulation, i.e. increased sensitivity) to leptin with asymmetry as an adverse response to stress (hormesis), mediated bilaterally mainly to the growing trunk via the sympathetic nervous system <it>(leptin-hypothalamic-sympathetic nervous system (LHS) concept)</it>. The putative autonomic dysfunction is thought to be increased by any lower circulating leptin levels associated with relatively lower BMIs. Sympathetic nervous system activation with asymmetry leads to asymmetries in ribs and/or vertebrae producing severe TA when beyond the capacity of postural mechanisms of the somatic nervous system to control the shape distortion of the trunk. A test of this hypothesis testing skin sympathetic responses, as in the Rett syndrome, is suggested.</p

Host-plants of leaf-miners in Australian subtropical rainforest

Leaf-miners are endophytic insect herbivores that are considered to be relatively host-specific compared with other types of insect herbivores, often depending on one or a few congeneric hosts. Because of their degree of host-specificity, they may be particularly vulnerable to environmental change. Despite this, little is known about the host-plants and life histories of the Australian leaf-mining fauna. Here we present new information on the host-plant use of leaf-miners occurring in Australian subtropical rainforest. We repeatedly hand-collected leaf-miners at 14 sampling sites in the ‘Tweed Caldera’ subtropical rainforest region of south-eastern Queensland and north-eastern New South Wales, Australia. Leaf-miners and their host-plants were identified to species (or morphospecies in the case of some leaf-miners). Within the region, a total of 106 plant species was recorded as leaf-miner hosts, on which a total of 12 679 individual leaf-miners was counted, belonging to 50 different species. We measured the local host-plant range of each leaf-miner species for which we had reliable incidence records across sampling sites (24 species). Local host-specificity was relatively high with 66.7 % of species recorded from a single or two congeneric host-plants. 16.7 % of species were restricted to a single plant family and 16.7 % were recorded on a few to several plants of the same plant order or across a range of unrelated host-plants

Mobile energy depot feasibility study: summary report

Declassified 28 Aug 1973. Various methods of producing and using nuclear power for military land vehicles and other military equipment were investigated and evaluated. A nuclear-powered mobile energy depot (MED) would move with advancing armies and produce vehicle fuels from materials readily available in the field. This would make mechanized units independent of external fuel supplies for extended periods, and permit them to move quickly and easily to areas impossible for units that depend on the customary fuel supply lines. Many possible MED systems were evaluated on the basis of energy sources, fuel manufacturing (by both conventional and chemonuclear processes), fuel storage and transportation, and fuel utilization in both present-day internal-combustion engines and power units of the future (i.e., fuel cells). The applications of more than a dozen MED systems to vehicular propulsion were studied. (auth