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

Study of trunk asymmetry in normal children and adolescents

The scoliometer readings in both standing and sitting position of 2071 children and adolescents (1099 boys and 972 girls) aged from 5 to 18 years old were studied. The angle of trunk rotation (ATR) was measured, in order to quantify the existing trunk asymmetry. Children and adolescents were divided in two groups according to the severity of trunk asymmetry. In the first group asymmetry was 1 to 6 degrees and in the second group was 7 or more degrees. Radiographic and leg length inequality evaluation were also performed in a number of children. The mean frequency of symmetric (ATR = 0 degrees) boys and girls was 67.06% and 65.01% for the standing screening position and 76.5% and 75.1% for the sitting position, respectively. The mean difference of frequency of asymmetry (ATR > 0 degrees) at standing minus sitting forward bending position for boys and girls was 10.22% and 9.37%, respectively. The mean frequency of asymmetry of 7 or more degrees was 3.23% for boys and 3.92% for girls at the standing forward bending position and 1.62% and 2.21% at the sitting, respectively. Girls are found to express higher frequency of asymmetry than boys. Right trunk asymmetry was more common than left. The sitting position is the preferred screening position for examining the rib or loin hump during school screening as it demonstrates the best correlation with the spinal deformity exposing the real trunk asymmetry

Study of PM10 and PM2.5 levels in three European cities: Analysis of intra and inter urban variations

In the present paper, 1-year PM10 and PM 2.5 data from roadside and urban background monitoring stations in Athens (Greece), Madrid (Spain) and London (UK) are analysed in relation to other air pollutants (NO,NO2,NOx,CO,O3 and SO2)and several meteorological parameters (wind velocity, temperature, relative humidity, precipitation, solar radiation and atmospheric pressure), in order to investigate the sources and factors affecting particulate pollution in large European cities. Principal component and regression analyses are therefore used to quantify the contribution of both combustion and non-combustion sources to the PM10 and PM 2.5 levels observed. The analysis reveals that the EU legislated PM 10 and PM2.5 limit values are frequently breached, forming a potential public health hazard in the areas studied. The seasonal variability patterns of particulates varies among cities and sites, with Athens and Madrid presenting higher PM10 concentrations during the warm period and suggesting the larger relative contribution of secondary and natural particles during hot and dry days. It is estimated that the contribution of non-combustion sources varies substantially among cities, sites and seasons and ranges between 38-67% and 40-62% in London, 26-50% and 20-62% in Athens, and 31-58% and 33-68% in Madrid, for both PM10 and PM 2.5. Higher contributions from non-combustion sources are found at urban background sites in all three cities, whereas in the traffic sites the seasonal differences are smaller. In addition, the non-combustion fraction of both particle metrics is higher during the warm season at all sites. On the whole, the analysis provides evidence of the substantial impact of non-combustion sources on local air quality in all three cities. While vehicular exhaust emissions carry a large part of the risk posed on human health by particle exposure, it is most likely that mitigation measures designed for their reduction will have a major effect only at traffic sites and additional measures will be necessary for the control of background levels. However, efforts in mitigation strategies should always focus on optimal health effects

Advantages of the Ilizarov external fixation in the management of intra-articular fractures of the distal tibia

<p>Abstract</p> <p>Background</p> <p>Treatment of distal tibial intra-articular fractures is challenging due to the difficulties in achieving anatomical reduction of the articular surface and the instability which may occur due to ligamentous and soft tissue injury. The purpose of this study is to present an algorithm in the application of external fixation in the management of intra-articular fractures of the distal tibia either from axial compression or from torsional forces.</p> <p>Materials and methods</p> <p>Thirty two patients with intra-articular fractures of the distal tibia have been studied. Based on the mechanism of injury they were divided into two groups. Group I includes 17 fractures due to axial compression and group II 15 fractures due to torsional force. An Ilizarov external fixation was used in 15 patients (11 of group I and 4 of group II). In 17 cases (6 of group I and 11 of group II) a unilateral hinged external fixator was used. In 7 out of 17 fractures of group I an additional fixation of the fibula was performed.</p> <p>Results</p> <p>All fractures were healed. The mean time of removal of the external fixator was 11 weeks for group I and 10 weeks for group II. In group I, 5 patients had radiological osteoarthritic lesions (grade III and IV) but only 2 were symptomatic. Delayed union occurred in 3 patients of group I with fixed fibula. Other complications included one patient of group II with subluxation of the ankle joint after removal of the hinged external fixator, in 2 patients reduction found to be insufficient during the postoperative follow up and were revised and 6 patients had a residual pain. The range of ankle joint motion was larger in group II.</p> <p>Conclusion</p> <p>Intra-articular fractures of the distal tibia due to axial compression are usually complicated with cartilaginous problems and are requiring anatomical reduction of the articular surface. Fractures due to torsional forces are complicated with ankle instability and reduction should be augmented with ligament repair, in order to restore normal movement of talus against the mortise. Both Ilizarov and hinged external fixators are unable to restore ligamentous stability. External fixation is recommended only for fractures of the ankle joint caused by axial compression because it is biomechanically superior and has a lower complication rate.</p

Inter-annual trends of ultrafine particles in urban Europe

Ultrafine particles (UFP, those with diameters ≤ 100 nm), have been reported to potentially penetrate deeply into the respiratory system, translocate through the alveoli, and affect various organs, potentially correlating with increased mortality. The aim of this study is to assess long-term trends (5–11 years) in mostly urban UFP concentrations based on measurements of particle number size distributions (PNSD). Additionally, concentrations of other pollutants and meteorological variables were evaluated to support the interpretations. PNSD datasets from 12 urban background (UB), 5 traffic (TR), 3 suburban background (SUB) and 1 regional background (RB) sites in 15 European cities and 1 in the USA were evaluated. The non-parametric Theil-Sen's method was used to detect monotonic trends. Meta-analyses were carried out to assess the overall trends and those for different environments. The results showed significant decreases in NO, NO2, BC, CO, and particle concentrations in the Aitken (25–100 nm) and the Accumulation (100–800 nm) modes, suggesting a positive impact of the implementation of EURO 5/V and 6/VI vehicle standards on European air quality. The growing use of Diesel Particle Filters (DPFs) might also have clearly reduced exhaust emissions of BC, PM, and the Aitken and Accumulation mode particles. However, as reported by prior studies, there remains an issue of poor control of Nucleation mode particles (smaller than 25 nm), which are not fully reduced with current DPFs, without emission controls for semi-volatile organic compounds, and might have different origins than road traffic. Thus, contrasting trends for Nucleation mode particles were obtained across the cities studied. This mode also affected the UFP and total PNC trends because of the high proportion of Nucleation mode particles in both concentration ranges. It was also found that the urban temperature increasing trends might have also influenced those of PNC, Nucleation and Aitken modes.</p

Association between adolescent idiopathic scoliosis prevalence and age at menarche in different geographic latitudes

BACKGROUND: Age at menarche is considered a reliable prognostic factor for idiopathic scoliosis and varies in different geographic latitudes. Adolescent idiopathic scoliosis prevalence has also been reported to be different in various latitudes and demonstrates higher values in northern countries. A study on epidemiological reports from the literature was conducted to investigate a possible association between prevalence of adolescent idiopathic scoliosis and age at menarche among normal girls in various geographic latitudes. An attempt is also made to implicate a possible role of melatonin in the above association. MATERIAL-METHODS: 20 peer-reviewed published papers reporting adolescent idiopathic scoliosis prevalence and 33 peer-reviewed papers reporting age at menarche in normal girls from most geographic areas of the northern hemisphere were retrieved from the literature. The geographic latitude of each centre where a particular study was originated was documented. The statistical analysis included regression of the adolescent idiopathic scoliosis prevalence and age at menarche by latitude. RESULTS: The regression of prevalence of adolescent idiopathic scoliosis and age at menarche by latitude is statistically significant (p < 0.001) and are following a parallel declining course of their regression curves, especially in latitudes northern than 25 degrees. CONCLUSION: Late age at menarche is parallel with higher prevalence of adolescent idiopathic scoliosis. Pubarche appears later in girls that live in northern latitudes and thus prolongs the period of spine vulnerability while other pre-existing or aetiological factors are contributing to the development of adolescent idiopathic scoliosis. A possible role of geography in the pathogenesis of idiopathic scoliosis is discussed, as it appears that latitude which differentiates the sunlight influences melatonin secretion and modifies age at menarche, which is associated to the prevalence of idiopathic scoliosis

A Unification- and Object-Based Symbolic Computation System

this paper are: First to extend the one-way pattern matching to (ac-) unification for AlgBench and therefore to increase the expressive power of its language. Second, to extend the type-constrained pattern matching by taking into account inheritance information in the unification process from a user-defined hierarchy of object types. 2 Extending Matching to Unificatio

Efficient Integration of Declarative Paradigms into Symbolic Computation Systems

. This paper describes the efficient integration of the functional, logic and constraint paradigms into symbolic computation systems. Moreover, it proposes the constraint logic paradigm for the programming language of symbolic computation systems. First, it describes the integration of a separate constraint logic inference engine with the functional language of the symbolic computation system AlgBench. The procedural, functional, and APL-like programming styles are inherited from Mathematica and are integrated on top of its term-rewriting mechanism. The proposed language could serve as a stand alone programming language. Second, it shows the efficient compilation of the resulting language to an intermediate code. The compiler generates code for a uniform abstract machine (extended WAM) which is achieved in an object-oriented way. 1 Introduction The new generation of symbolic computation systems, such as MathematicaÔ [21] or AXIOMÔ [13] provides beyond the usual mathematical and calcul..

Particulate matter concentrations in the atmosphere of Athens: spatial and temporal variability – predictive models

The aim of the dissertation was to study the particle pollution problem in Athens, as it was established during the period that followed the promulgation of EU directive 99/30/EC. Field measurements were conducted for the characterization of ambient particle concentrations. Measurements were centered on PM10, PM2.5 and PM1 fractions, on total number concentrations (TNC) and their size distributions and on the chemical composition of particles regarding elemental and organic carbon. The characterization process was directed towards the identification of factors controlling temporal/spatial variations of concentration levels. Data utilization was carried out in a stochastic data mining framework, involving exploratory and inferential statistics, multivariate analysis, time-series and spectral analysis and geostatistics. The findings from the characterization procedure were employed in the development of predictive models for particle concentrations. Regression mapping models, using GIS data, were built for spatial estimation. Spatial interpolation models were evaluated in parallel. Artificial neural networks comprised the principal methodology used for short-term forecasting and they were assessed comparatively to alternative methods (MLR, ARIMA, PLSR, CART). Input variable selection techniques were examined (e.g. genetic algorithms) and the efficiency of network training with local and global (simulated annealing) optimization algorithms was tested. The results revealed exceedances of limit values for PM10 and PM2.5 concentrations, while PM1 levels were elevated as well. Statistical associations between particle mass and number (TNC) concentrations were very weak. While elemental carbon levels were characterized as moderate, organic carbon levels were high, thus making organic aerosols the chemical group with the highest participation in particle mass. By means of the EC tracer methodology it was concluded that a significant fraction of organic particles in the area is of secondary origin. Vehicular traffic, secondary processes and intra-urban transport were determined as the principal factors associated to the observed temporal variability. At the spatial level, while the distribution of concentration levels displayed moderate heterogeneity, significant correlations were observed among measurement locations. The developed models for spatial estimation produced a very strong performance, also providing satisfactory mapping of PM10 annual levels in the area. Regarding short-term forecasting, two model categories where examined; for daily mean and hourly PM10 concentrations, 24-h in advance at various locations within the study area. The predictive ability of neural network models was high, especially in comparison to alternative statistical models.Αντικείμενο της διατριβής αποτέλεσε η μελέτη του προβλήματος της σωματιδιακής ρύπανσης στην Αθήνα, όπως διαμορφώθηκε κατά την περίοδο που ακολούθησε την εξαγγελία της οδηγίας 99/30/EC. Βασικό μέσο προσέγγισης ήταν η πραγματοποίηση μετρήσεων πεδίου για τον χαρακτηρισμό των αιωρουμένων σωματιδίων. Οι μετρήσεις επικεντρώθηκαν στα κλάσματα PM10, PM2.5 και PM1, στις κατ’αριθμό ολικές σωματιδιακές συγκεντρώσεις (TNC) και τις κατανομές τους και στη χημική σύσταση των σωματιδίων σε στοιχειακό και οργανικό άνθρακα. Η κύρια κατεύθυνση της διαδικασίας χαρακτηρισμού στοχεύει στον εντοπισμό των παραγόντων που ελέγχουν τις χρονικές/χωρικές διακυμάνσεις των επιπέδων. Η αξιοποίηση των μετρήσεων πραγματοποιήθηκε σε ένα πλαίσιο στοχαστικής ανάλυσης δεδομένων, που περιέλαβε τεχνικές διερευνητικής και επαγωγικής στατιστικής, πολυμεταβλητής ανάλυσης, ανάλυσης χρονοσειρών - φασματικής ανάλυσης και γεωστατιστικής. Τα ευρήματα απ’ τη διαδικασία χαρακτηρισμού αξιοποιήθηκαν στην ανάπτυξη μοντέλων πρόβλεψης συγκεντρώσεων. Για την χωρική εκτίμηση, αναπτύχθηκαν μοντέλα τύπου regression mapping, με χρήση δεδομένων GIS. Παράλληλα αξιολογήθηκαν μοντέλα χωρικής παρεμβολής.Κύρια μεθοδολογία χρονικής πρόρρησης ήταν τα τεχνητά νευρωνικά δίκτυα, τα οποία αξιολογήθηκαν συγκριτικά με εναλλακτικές μεθόδους (MLR, ARIMA, PLSR, CART). Εξετάσθηκαν τεχνικές επιλογής μεταβλητών εισόδου (όπως γενετικοί αλγόριθμοι) και η αποτελεσματικότητα της εκμάθησης με αλγορίθμους τοπικής και ολικής (προσομοιωμένη ανόπτηση) βελτιστοποίησης.Από τα αποτελέσματα προέκυψαν υπερβάσεις των οριακών τιμών για τις συγκεντρώσεις PM10 και PM2.5, ενώ υψηλά ήταν τα επίπεδα PM1. Οι συσχετίσεις μεταξύ των κατά μάζα και κατ’αριθμό συγκεντρώσεων ΤΝC ήταν ασθενέστατες. Ενώ τα επίπεδα στοιχειακού άνθρακα χαρακτηρίζονται ως μέτρια, για τον οργανικό άνθρακα ήταν υψηλά, αναδεικνύοντας τα οργανικά σωματίδια ως τη χημική ομάδα με την υψηλότερη συμμετοχή στις συγκεντρώσεις PM. Διαπιστώθηκε, μέσω της μεθοδολογίας EC tracer, ότι σημαντικό ποσοστό των οργανικών σωματιδίων είναι δευτερογενούς προέλευσης.Ως κύριοι παράγοντες που σχετίζονται με τις παρατηρούμενες χρονικές διακυμάνσεις, προσδιορίσθηκαν η κυκλοφορία οχημάτων, οι δευτερογενείς διαδικασίες σχηματισμού και η ενδο-αστική μεταφορά. Σε χωρικό επίπεδο, ενώ η κατανομή των επιπέδων είναι σχετικά ανομοιογενής, παρατηρούνται σημαντικές συσχετίσεις μεταξύ θέσεων μέτρησης.Τα μοντέλα χωρικής πρόβλεψης PM10 που αναπτύχθηκαν εμφάνισαν πολύ υψηλή απόδοση, παρέχοντας ικανοποιητική χαρτογραφική απεικόνιση των επιπέδων PM10 στην περιοχή. Σχετικά με τη βραχυχρόνια σημειακή πρόβλεψη αναπτύχθηκαν δυο κατηγορίες μοντέλων, για μέσες ημερήσιες και ωριαίες συγκεντρώσεις PM10 της επόμενης ημέρας, σε διάφορες θέσεις στην περιοχή. Η προγνωστική ικανότητα των μοντέλων νευρωνικών δικτύων ήταν υψηλή, ειδικά σε σύγκριση με τα εναλλακτικά στατιστικά μοντέλα. Από την περίληψη θα ληφθούν υπ’ όψη μόνο οι πρώτοι 2500 χαρακτήρες μαζί με τα κενά (~450 λέξεις). στις κατ’αριθμό ολικές σωματιδιακές συγκεντρώσεις (TNC) και τις κατανομές τους και στη χημική σύσταση των σωματιδίων σε στοιχειακό και οργανικό άνθρακα. Η κύρια κατεύθυνση της διαδικασίας χαρακτηρισμού στοχεύει στον εντοπισμό των παραγόντων που ελέγχουν τις χρονικές/χωρικές διακυμάνσεις των επιπέδων. Η αξιοποίηση των μετρήσεων πραγματοποιήθηκε σε ένα πλαίσιο στοχαστικής ανάλυσης δεδομένων, που περιέλαβε τεχνικές διερευνητικής και επαγωγικής στατιστικής, πολυμεταβλητής ανάλυσης, ανάλυσης χρονοσειρών - φασματικής ανάλυσης και γεωστατιστικής. Τα ευρήματα απ’ τη διαδικασία χαρακτηρισμού αξιοποιήθηκαν στην ανάπτυξη μοντέλων πρόβλεψης συγκεντρώσεων. Για την χωρική εκτίμηση, αναπτύχθηκαν μοντέλα τύπου regression mapping, με χρήση δεδομένων GIS. Παράλληλα αξιολογήθηκαν μοντέλα χωρικής παρεμβολής.Κύρια μεθοδολογία χρονικής πρόρρησης ήταν τα τεχνητά νευρωνικά δίκτυα, τα οποία αξιολογήθηκαν συγκριτικά με εναλλακτικές μεθόδους (MLR, ARIMA, PLSR, CART). Εξετάσθηκαν τεχνικές επιλογής μεταβλητών εισόδου (όπως γενετικοί αλγόριθμοι) και η αποτελεσματικότητα της εκμάθησης με αλγορίθμους τοπικής και ολικής (προσομοιωμένη ανόπτηση) βελτιστοποίησης.Από τα αποτελέσματα προέκυψαν υπερβάσεις των οριακών τιμών για τις συγκεντρώσεις PM10 και PM2.5, ενώ υψηλά ήταν τα επίπεδα PM1. Οι συσχετίσεις μεταξύ των κατά μάζα και κατ’αριθμό συγκεντρώσεων ΤΝC ήταν ασθενέστατες. Ενώ τα επίπεδα στοιχειακού άνθρακα χαρακτηρίζονται ως μέτρια, για τον οργανικό άνθρακα ήταν υψηλά, αναδεικνύοντας τα οργανικά σωματίδια ως τη χημική ομάδα με την υψηλότερη συμμετοχή στις συγκεντρώσεις PM. Διαπιστώθηκε, μέσω της μεθοδολογίας EC tracer, ότι σημαντικό ποσοστό των οργανικών σωματιδίων είναι δευτερογενούς προέλευσης.Ως κύριοι παράγοντες που σχετίζονται με τις παρατηρούμενες χρονικές διακυμάνσεις, προσδιορίσθηκαν η κυκλοφορία οχημάτων, οι δευτερογενείς διαδικασίες σχηματισμού και η ενδο-αστική μεταφορά. Σε χωρικό επίπεδο, ενώ η κατανομή των επιπέδων είναι σχετικά ανομοιογενής, παρατηρούνται σημαντικές συσχετίσεις μεταξύ θέσεων μέτρησης.Τα μοντέλα χωρικής πρόβλεψης PM10 που αναπτύχθηκαν εμφάνισαν πολύ υψηλή απόδοση, παρέχοντας ικανοποιητική χαρτογραφική απεικόνιση των επιπέδων PM10 στην περιοχή. Σχετικά με τη βραχυχρόνια σημειακή πρόβλεψη αναπτύχθηκαν δυο κατηγορίες μοντέλων, για μέσες ημερήσιες και ωριαίες συγκεντρώσεις PM10 της επόμενης ημέρας, σε διάφορες θέσεις στην περιοχή. Η προγνωστική ικανότητα των μοντέλων νευρωνικών δικτύων ήταν υψηλή, ειδικά σε σύγκριση με τα εναλλακτικά στατιστικά μοντέλα. Από την περίληψη θα ληφθούν υπ’ όψη μόνο οι πρώτοι 2500 χαρακτήρες μαζί με τα κενά (~450 λέξεις). Η περίληψη πρέπει να περιλαμβάνει τον στόχο, τη μεθοδολογία και τα αποτελέσματα - συμπεράσματα της διατριβής