932 research outputs found
Interlinked signaling feedback loops and self-regulation during vertebrate limb development
No full textReliable organ and tissue morphogenesis seems to depend on self-regulatory mechanisms that are able to buffer spontaneous and/or genetic variations. While the analysis of the interactions of BMPs with their antagonists during gastrulation has provided insights into the self-regulatory capacity of early embryos, few other mechanisms endowing developmental programmes with robustness have been identified. Limb development and digit specification are regulated by epithelial-mesenchymal (e-m) interactions involving instructive SHH and FGF signaling. The BMP antagonist Gremlin1 (GREM1) is key to establishing these interactions. By combining genetics with ex vivo manipulation and mathematical modeling, we establish that both BMP4 and SHH positively regulate Grem1 expression, defining this antagonist as a critical node that links a fast and self-regulatory BMP4/GREM1 module to the SHH/GREM1/FGF e-m feedback loop. This network architecture allows a self-regulative switch from BMP4- to SHH-driven limb development and endows limb patterning with robustness against variations in gene activity due to interconnectivity between the BMP, SHH and FGF signaling pathways. The establishment of this robust signaling network may have contributed to the appearance and stabilization of pentadactyly in tetrapods
Analysis of lower limb internal kinetics and electromyography in elite race walking.
No full textThe aim of this study was to analyse lower limb joint moments, powers and electromyography patterns in elite race walking. Twenty international male and female race walkers performed at their competitive pace in a laboratory setting. The collection of ground reaction forces (1000 Hz) was synchronised with two-dimensional high-speed videography (100 Hz) and electromyography of seven lower limb muscles (1000 Hz). As well as measuring key performance variables such as speed and stride length, normalised joint moments and powers were calculated. The rule in race walking which requires the knee to be extended from initial contact to midstance effectively made the knee redundant during stance with regard to energy generation. Instead, the leg functioned as a rigid lever which affected the role of the hip and ankle joints. The main contributors to energy generation were the hip extensors during late swing and early stance, and the ankle plantarflexors during late stance. The restricted functioning of the knee during stance meant that the importance of the swing leg in contributing to forward momentum was increased. The knee flexors underwent a phase of great energy absorption during the swing phase and this could increase the risk of injury to the hamstring muscles
Pulmonary function at follow up of very preterm infants from the United Kingdom Oscillation Study
No full textPrematurely born infants supported by conventional ventilation frequently have abnormal pulmonary function when assessed in childhood. The aim of this study was to test the hypothesis that infants who were randomly assigned to high frequency oscillatory ventilation would have superior pulmonary function at follow-up to those who received conventional ventilation (United Kingdom Oscillation Study). Infants from 12 trial centres were recruited for pulmonary function testing at a single centre. Seventy-six infants, of mean gestational age 26.4 weeks, were studied following sedation with chloral hydrate at between 11 and 14 months of age, corrected for prematurity. Infants assigned to conventional ventilation had similar pulmonary function to those assigned to high frequency oscillatory ventilation, with mean (SD) results as follows: functional residual capacity measured by whole body plethysmography 26.9 (6.3) vs. 26.5 (6.4) ml/kg; functional residual capacity measured by helium dilution 24.1 (5.4) vs. 23.5 (5.7) ml/kg; inspiratory airway resistance 3.3 (1.3) vs. 3.4 (1.6) kPa/(l/s); expiratory airway resistance 4.4 (2.8) vs. 4.1 (2.5) kPa/(l/s); respiratory rate 31.2 (6.0) vs. 33.9 (8.0) breaths/minute. We conclude that early use of high frequency oscillatory ventilation in very preterm infants appears to offer no advantage over conventional ventilation in terms of pulmonary function at follow-u
Randomised trial of high frequency oscillatory ventilation or conventional ventilation in babies of gestational age 28 weeks or less: respiratory and neurological outcomes at 2 years
No full textBackground The long term outcome of children entered into neonatal trials of high frequency oscillatory
ventilation (HFOV) or conventional ventilation (CV) has been rarely studied.Objective To evaluate respiratory and neurodevelopmental outcomes for children entered into the United
Kingdom Oscillation Study, which was designed to evaluate these outcomes.Methods Surviving infants were followed until 2 years of age corrected for prematurity. Study forms were completed by local paediatricians at routine assessments, and parents were asked to complete a validated neurodevelopmental questionnaire.
Results: Paediatricians’ forms were returned for 73% of the 585 surviving infants. Respiratory symptoms were common in all infants, and 41% had received inhaled medication. Mode of ventilation had no effect on frequency of any symptoms. At 24 months of age, severe neurodevelopmental disability was present in 9% and other disabilities in 38% of children, but the prevalence of disability was similar in children who
received HFOV or CV (relative risk 0.93; 95% confidence interval 0.74 to 1.16). The prevalence of disability did not vary by gestational age, but boys were more likely to have overall disability. Developmental scores were unaffected by mode of ventilation (relative risk 1.13; 95% confidence interval
0.78 to 1.63) and were lower in infants born before 26 weeks gestation compared with babies born at 26–28 weeks.Conclusions Initial mode of ventilation in very preterm infants has no impact on respiratory or neurodevelopmental morbidity at 2 years. HFOV and CV appear equally effective for the early treatment
of respiratory distress syndrome. The effects of high frequency oscillatory ventilation (HFOV) and conventional ventilation (CV) on short term respiratory and neurological morbidity have been compared in several studies.1–10 Such short term observations may have poor predictive value for outcome in childhood, but to date only two reports have provided information about long term outcome. The HiFi trial evaluated respiratory morbidity and neurodevelopmental outcome up to 2 years of post-term age for 77% of survivors.11 Growth and clinical respiratory status did not differ between the two groups, but neurodevelopmental outcome was worse in the HFOV group, in keeping with the excess of major cranial ultrasound
abnormalities identified in the original report. This study
used a low volume HFOV strategy, which is now thought to
be suboptimal in preterm infants with respiratory distress
syndrome
Germanismen im Verpolnischungswörterbuch von E.S. Kortowicz (1891)
No full textOut of concern for language ‘purity’ ‘Polonizing’ dictionaries/dictionaries of Polish equivalents were published in Poland, whose authors (language purists) aimed to replace words/expressions of foreign origin with native-language equivalents (or with assimilated loanwords). Besides Latinisms or Gallicisms under criticism were also German loanwords. The main focus of the paper is on the presentation of the dictionary by E.S. Kortowicz (1891), in which the author seeks to eliminate Germanisms from the Polish language.W trosce o „czystość” językową w Polsce tworzone były „słowniki spolszczające”/,,słowniki spolszczeń”, w których autorzy (puryści językowi) próbowali zastępować wyrazy/wyrażenia pochodzenia obcego rodzimymi ekwiwalentami (lub zasymilowanymi zapożyczeniami). Obok latynizmów czy galicyzmów piętnowano w nich często zapożyczenia z języka niemieckiego. Centralną część publikacji stanowi opis pracy E.S. Kortowicza (1891), w której autor dąży do wyeliminowania germanizmów z języka polskiego
Dataset for PhD Thesis "Data Technologies for Lower Limb Orthosis Design and Assessment"
No full textThis dataset supports the Thesis:
by Kelly, E.S.
TITLE- Data Technologies for Lower Limb Orthosis Design and Assessment
The thesis featured participant testing (Chapter 3) and secondary analysis of MR and clinical data (Chapters 4-6).
Due to participant confidentiality constraints of the original study ethics, the imaging data are not enclosed in this raw data file.
This dataset contains: A simple Excel spreadsheet containing the raw data behind the tables and figures in the linked thesis.
</span
The effect of different skin-ankle brace application pressures with and without shoes on single-limb balance, electromyographic activation onset and peroneal reaction time of lower limb muscles
No full textBackground: Several studies have been carried out in order to investigate the effect of ankle bracing on ankle joint function and performance. However, no study so far has examined the role of skin-brace interface pressure in neuromuscular control. The aim of this study was to investigate the effect of different skin-ankle brace interface pressures, with and without shoes, on quiet single-limb balance and the electromyographic (EMG) activation sequence of four lower limb muscles. Methods: Twelve male physical education students who volunteered to take part in the study were measured with and without shoes under three ankle brace conditions: (i) without brace, (ii) with brace and 30 kilopascals (kPa) application pressure and (iii) with brace and 60 kPa application pressure. Single-limb balance (anteroposterior and mediolateral parameter) was assessed on the dominant lower limb, with open and closed eyes, on a force platform, simultaneously with the EMG recording of four lower lower limb muscles' (gastrocnemius, peroneus longus, rectus femoris and biceps femoris) activation onset. Peroneus longus reaction time was also measured by provoking a sudden subtalar inversion stress test using a trap-door. Results: The results showed that the application of athletic footwear resulted in a significant difference between the condition with shoes and without shoes, with a significantly increased anteroposterior sway and sway velocity, in all three ankle brace application conditions with shoes (F = 50.9, d.f. = 1, p < 0.001 and F = 58.4, d.f. = 1, p < 0.001), but had no effect in the mediolateral stability, or the total stability parameter. Shoes had no significant effect on the EMG activation sequence of the four lower limb muscles. Lastly, ankle brace application with 30 and 60 kPa application pressures, with and without athletic footwear, led to a significant delay in the peroneus longus reaction time (F = 9.71, d.f. = 2, p < 0.001). Conclusions: These findings suggest that different ankle brace application pressures may have an effect on single-limb balance, and peroneal reaction time. The application of athletic footwear, further adversely affects these parameters significantly. Further research is needed in this area with more dynamic and functional measurements, before the safe use of ankle bracing can be widely recommended. © 2008 Elsevier Ltd. All rights reserved
Maternal occupation in agriculture and risk of limb defects in Washington State, 1980-1993
No full textObjectives. This study examined the association between maternal occupational exposure to agricultural chemicals and the risk of limb defects among offspring. Methods. A retrospective cohort study was conducted using Washington State birth records for the years 1980 through 1993. The exposed group, consisting of 4466 births to mothers employed in agriculture, was compared with 2 reference groups: (i) 23 512 births in which neither parent worked in agriculture (″nonagricultural″ group) and (ii) 5994 births in which only the father worked in agriculture (″paternal agriculture″ group). The outcome of interest was limb defects [syndactyly, polydactyly, adactyly, and ″other limb reductions″ (as listed in the birth record)]. Results. An elevated risk of limb defects was observed for the exposed group in comparison with both the nonagricultural and paternal agriculture groups, with ethnicity-adjusted prevalence ratios of 2.6 [95% confidence interval (95% CI) 1.1-5.8] and 2.6 (95% CI 0.7-9.5), respectively. Conclusions. These results support the hypothesis that maternal occupational exposure to agricultural chemicals may increase the risk of giving birth to a child with limb defects
Methods of reliability assessment of heterogeneous redundant systems
No full textAccepted Author ManuscriptTransport Engineering and Logistic
Notch1 and 2 cooperate in limb ectoderm to receive an early Jagged2 signal regulating interdigital apoptosis
No full textAbstractSpontaneous and engineered mutations in the Notch ligand Jagged2 produced the Syndactylism phenotype (Jiang, R.L., Lan, Y., Chapman, H.D., Shawber, C., Norton, C.R., Serreze, D.V., Weinmaster, G., Gridley, T., 1998. Defects in limb, craniofacial, and thymic Development in Jagged2 mutant mice. Genes Dev. 12, 1046–1057; Sidow, A., Bulotsky, M.S., Kerrebrock, A.W., Bronson, R.T., Daly, M.J., Reeve, M.P., Hawkins, T.L., Birren, B.W., Jaenisch, R., Lander, E.S., 1997. Serrate2 is disrupted in the mouse limb-development mutant syndactylism. Nature 389, 722–725). Given that additional ligands may be expressed in the developing limb bud, it was possible that loss of Jagged2 disabled only part of Notch function in the limb. In addition, it is not clear from the expression pattern of Jagged2 in the apical ectodermal ridge (AER) whether the ectodermal or mesenchymal compartment of the limb bud receives the Jagged2 signal. To elucidate the requirement for the Notch pathway in limb development, we have analyzed single and compound Notch receptor mutants as well as γ-secretase-deficient limbs. Floxed alleles were removed either from the developing limb bud ectoderm (using Msx2-Cre) or from the mesenchyme (using Prx1-Cre). Our results confirm that Jagged2 loss describes the contribution of the entire Notch pathway to the mouse limb development and revealed that both Notch1 and 2 are required in the ectoderm to receive the Jagged2 signal. Interestingly, our allelic series allowed us to determine that Notch receives this signal at an early stage in the developmental process and that memory of this event is retained by the mesenchyme, where Notch signaling appears to be dispensable. Thus, Notch signaling plays a non-autonomous role in digit septation
- …
