Biomechanical and metabolic aspects of backward (and forward) running on uphill gradients: another clue towards an almost inelastic rebound.

PURPOSE: On level, the metabolic cost (C) of backward running is higher than forward running probably due to a lower elastic energy recoil. On positive gradient, the ability to store and release elastic energy is impaired in forward running. We studied running on level and on gradient to test the hypothesis that the higher metabolic cost and lower efficiency in backward than forward running was due to the impairment in the elastic energy utilisation. METHODS: Eight subjects ran forward and backward on a treadmill on level and on gradient (from 0 to + 25%, with 5% step). The mechanical work, computed from kinematic data, C and efficiency (the ratio between total mechanical work and C) were calculated in each condition. RESULTS: Backward running C was higher than forward running at each condition (on average + 35%) and increased linearly with gradient. Total mechanical work was higher in forward running only at the steepest gradients, thus efficiency was lower in backward running at each gradient. CONCLUSION: Efficiency decreased by increasing gradient in both running modalities highlighting the impairment in the elastic contribution on positive gradient. The lower efficiency values calculated in backward running in all conditions pointed out that backward running was performed with an almost inelastic rebound; thus, muscles performed most of the mechanical work with a high metabolic cost. These new backward running C data permit, by applying the recently introduced 'equivalent slope' concept for running acceleration, to obtain the predictive equation of metabolic power during level backward running acceleration.

Synaptic-dependent developmental dysconnectivity in 22q11.2 deletion syndrome.

Chromosome 22q11.2 deletion is among the strongest known genetic risk factors for neuropsychiatric disorders, including autism and schizophrenia. Brain imaging studies have reported disrupted large-scale functional connectivity in people with 22q11 deletion syndrome (22q11DS). However, the significance and biological determinants of these functional alterations remain unclear. Here, we use a cross-species design to investigate the developmental trajectory and neural underpinnings of brain dysconnectivity in 22q11DS. We find that LgDel mice, an established mouse model of 22q11DS, exhibit age-specific patterns of functional MRI (fMRI) dysconnectivity, with widespread fMRI hyper-connectivity in juvenile mice reverting to focal hippocampal hypoconnectivity over puberty. These fMRI connectivity alterations are mirrored by co-occurring developmental alterations in dendritic spine density, and are both transiently normalized by developmental GSK3ß inhibition, suggesting a synaptic origin for this phenomenon. Notably, analogous hyper- to hypoconnectivity reconfiguration occurs also in human 22q11DS, where it affects hippocampal and cortical regions spatially enriched for synaptic genes that interact with GSK3ß, and autism-relevant transcripts. Functional dysconnectivity in somatomotor components of this network is predictive of age-dependent social alterations in 22q11.2 deletion carriers. Taken together, these findings suggest that synaptic-related mechanisms underlie developmentally mediated functional dysconnectivity in 22q11DS.

Skyscraper running: physiological and biomechanical profile of a novel sport activity.

Skyscraper running is here analyzed in terms of mechanical and metabolic requirements, both at the general and at the individual level. Skyscraper runners' metabolic profile has been inferred from the total mechanical power estimated in 36 world records (48-421 m tall buildings), ranked by gender and age range. Individual athlete's performance (n=13) has been experimentally investigated during the Pirelli Vertical Sprint, with data loggers for altitude and heart rate (HR). At a general level, a non-linear regression of Wilkie's model relating maximal mechanical power to event duration revealed the gender and age differences in terms of maximum aerobic power and anaerobic energy resources particularly needed at the beginning of the race. The total mechanical power was found to be partitioned among: the fraction devolved to raise the body center of mass , the need to accelerate the limbs with respect to the body , and running in turns between flights of stairs . At the individual level, experiments revealed that these athletes show a metabolic profile similar to middle-distance runners. Furthermore, best skyscraper runners maintain a constant vertical speed and HR throughout the race, while others suddenly decelerate, negatively affecting the race performance.

Impact of the shift from NCHS growth reference to WHO(2006) growth standards in a therapeutic feeding programme in Niger.

OBJECTIVES: To describe the implementation of the WHO(2006) growth standards in a therapeutic feeding programme. METHODS: Using programme monitoring data from 21,769 children 6-59 months admitted to the Médecins Sans Frontières therapeutic feeding programme during 2007, we compared characteristics at admission, type of care and outcomes for children admitted before and after the shift to the WHO(2006) standards. Admission criteria were bipedal oedema, MUAC <110 mm, or weight-for-height (WFH) of <-70% of the median (NCHS) before mid-May 2007, and WFH <-3 z score (WHO(2006)) after mid-May 2007. RESULTS: Children admitted with the WHO(2006) standards were more likely to be younger, with a higher proportion of males, and less malnourished (mean WFH -3.6 z score vs. mean WFH -4.6 z score). They were less likely to require hospitalization or intensive care (28.4%vs. 77%; 12.8%vs. 36.5%) and more likely to be treated exclusively on an outpatient basis (71.6%vs. 23%). Finally, they experienced better outcomes (cure rate: 89%vs. 71.7%, death rate: 2.7%vs. 6.4%, default rate: 6.7%vs. 12.3%). CONCLUSIONS: In this programme, the WHO(2006) standards identify a larger number of malnourished children at an earlier stage of disease facilitating their treatment success.

[Left colon necrosis after endoscopic para-aortic lymph node exploration in a cervical carcinoma stage IIB]. / Nécrose colique gauche après un curage lomboaortique coelioscopique pour cancer du col utérin de stade IIB.

Authors report a left colon ischemia six days after laparoscopic para-aortic lymphadenectomy in the staging of advanced cervical carcinoma. Before surgery, positron emission tomography scanning was performed: there were no para-aortic nodal metastasis. The histologic examination confirmed the radiological staging. Positron emission tomography scanning could avoid surgery in the case of patients with high risks morbidity factors.

[Immediate and long term complications of episiotomy]. / Complications immédiates et à long terme de l'épisiotomie.

OBJECTIVE: The objective of this review was to describe the complications of episiotomy. MATERIAL AND METHODS: A systematic review on Medline Database set was performed with the key words: episiotomy, dyspareunia, fecal incontinence, urinary incontinence, maternal morbidity, pelvic floor defects and sexual function. Four hundred seventy two articles were selected. RESULTS: When performed liberally, episiotomy appears to increase the risk of post partum bleeding. More restrictive use does not appear to increase the risk of serious perineal injury. In the event of instrumental extraction, use of episiotomy appears to be associated with more severe damage. Medial episiotomy does not appear to be associated with third or fourth degree tears. Following delivery, patients who had an episiotomy complain of perineal pain more than those with an intact perineum or first or second degree tears. Three months after delivery, there is no difference. While episiotomy appears to be a source of dyspareunia during the first weeks after delivery in comparison with spontaneous tears, this does not appear to be true later after delivery. CONCLUSION: Episiotomy appears to be the cause of more perineal pain and dyspareunia during the early post partum weeks.

The biomechanics of skipping gaits: a third locomotion paradigm?

Skipping, a gait children display when they are about four- to five-years-old, is revealed to be more than a behavioural peculiarity. By means of metabolic and biomechanical measurements at several speeds, the relevance of skipping is shown to extend from links between bipedal and quadrupedal locomotion (namely galloping) to understanding why it could be a gait of choice in low-gravity conditions, and to some aspects of locomotion evolution (ground reaction forces of skipping seem to originate from pushing the walking gait to unnaturally high speeds). When the time-courses of mechanical energy and the horizontal ground reaction force are considered, a different locomotion paradigm emerges, enabling us to separate, among the bouncing gaits, the trot from the gallop (quadrupeds) and running from skipping (bipeds). The simultaneous use of pendulum-like and elastic mechanisms in skipping gaits, as shown by the energy curve analysis, helps us to understand the low cost of transport of galloping quadrupeds.

From bipedalism to bicyclism: evolution in energetics and biomechanics of historic bicycles.

We measured the metabolic cost (C) and mechanical work of riding historic bicycles at different speeds: these bicycles included the Hobby Horse (1820s), the Boneshaker (1860s), the High Wheeler (1870s), the Rover (1880s), the Safety (1890s) and a modern bicycle (1980s) as a mean of comparison. The rolling resistance and air resistance of each vehicle were assessed. The mechanical internal work (W(INT)) was measured from three-dimensional motion analysis of the Hobby Horse and modern bicycle moving on a treadmill at different speeds. The equation obtained from the modern bicycle data was applied to the other vehicles. We found the following results. (i) Apart from the Rover, which was introduced for safety reasons, every newly invented bicycle improved metabolic economy. (ii) The rolling resistance decreased with subsequent designs while the frontal area and, hence, aerodynamic drag was fairly constant (except for the High Wheeler). (iii) The saddle-assisted body weight relief (which was inaugurated by the Hobby Horse) was responsible for most of the reduction in metabolic cost compared with walking or running. Further reductions in C were due to decreases in stride/pedalling frequency and, hence, W(INT) at the same speeds. (iv) The introduction of gear ratios allowed the use of pedalling frequencies that optimize the power/contraction velocity properties of the propulsive muscles. As a consequence, net mechanical efficiency (the ratio between the total mechanical work and C) was almost constant (0.273 +/- 0.015s.d.) for all bicycle designs, despite the increase in cruising speed. In the period from 1820 to 1890, improved design of bicycles increased the metabolically equivalent speed by threefold compared with walking at an average pace of ca. + 0.5 ms(-1) per decade [corrected]. The speed gain was the result of concurrent technological advancements in wheeled, human-powered vehicles and of 'smart' adaptation of the same actuator (the muscle) to different operational conditions.

Mechanical and metabolic profile of locomotion in adults with childhood-onset GH deficiency.

OBJECTIVE: The aim of the present study was to evaluate the energy cost and the mechanical work of locomotion in a group of adults with childhood-onset GH deficiency (GHD). SUBJECTS: Eight males with childhood-onset GHD (mean age+/-s.d.: 31.7+/-3.6 years; mean height: 145.1+/-6.7cm) and six age-, sex- and exercise-matched normal subjects were studied. DESIGN: GHD patients and healthy controls were requested to walk and run in the speed range of 2-11km h(-1). For each condition, simultaneous mechanical and metabolic measurements were taken. METHODS: Oxygen consumption, and mechanical internal and external work of locomotion were evaluated with standard open-circuit respirometry and three-dimensional motion analysis respectively. RESULTS: External work was not significantly different between GHD patients and healthy controls, while internal work was higher for patients at all speeds. In walking, the relationships between both the mechanical energy recovery and the metabolic cost with speed were shifted towards lower speeds in patients. As a consequence, the optimal speed of walking, i.e. the speed at which the cost of locomotion is minimum, was lower for GHD patients. Stride frequency was significantly higher (11.2-11.3%) for GHD patients at all speeds of walking and running. GHD patients were unable to run at speeds higher than 8km h(-1) for the time needed to reach a metabolic steady state. CONCLUSION: It appears that both the mechanics and energetics of locomotion in short-statured adults with childhood-onset GHD are not strikingly different from those of healthy controls, thus demonstrating a substantial 'normality' in this group of GHD patients at metabolically attainable speeds. The 'harmonic' body structure and the adherence to allometric transformations in these patients do not exclude the possibility of a different metabolic role of GH in normally statured adults with childhood-onset GHD and in those with acquired GHD, taking into account the well recognized heterogeneity of the adult GHD syndrome.

Cellular prion protein binds laminin and mediates neuritogenesis.

Laminin (LN) plays a major role in neuronal differentiation, migration and survival. Here, we show that the cellular prion protein (PrPc) is a saturable, specific, high-affinity receptor for LN. The PrPc-LN interaction is involved in the neuritogenesis induced by NGF plus LN in the PC-12 cell line and the binding site resides in a carboxy-terminal decapeptide from the gamma-1 LN chain. Neuritogenesis induced by LN or its gamma-1-derived peptide in primary cultures from rat or either wild type or PrP null mice hippocampal neurons, indicated that PrPc is the main cellular receptor for that particular LN domain. These results point out to the importance of the PrPc-LN interaction for the neuronal plasticity mechanism.

Optimum gradient of mountain paths.

By combining the experiment results of R. Margaria (Atti Accad. Naz. Lincei Memorie 7: 299-368, 1938), regarding the metabolic cost of gradient locomotion, together with recent insights on gait biomechanics, a prediction about the most economical gradient of mountain paths (approximately 25%) is obtained and interpreted. The pendulum-like mechanism of walking produces a waste of mechanical work against gravity within the gradient range of up to 15% (the overall efficiency is dominated by the low transmission efficiency), whereas for steeper values only the muscular efficiency is responsible for the (slight) metabolic change (per meter of vertical displacement) with respect to gradient. The speeds at the optimum gradient turned out to be approximately 0.65 m/s (+0.16 m/s vertical) and 1.50 m/s (-0.36 m/s vertical), for uphill and downhill walking, respectively, and the ascensional energy expenditure was 0.4 and 2.0 ml O2.kg body mass-1.vertical m-1 climbed or descended. When the metabolic power becomes a burden, as in high-altitude mountaineering, the optimum gradient should be reduced. A sample of real mountain path gradients, experimentally measured, mimics the obtained predictions.

Maximal instantaneous muscular power after prolonged bed rest in humans.

A reduction in lower limb cross-sectional area (CSA) occurs after bed rest (BR). This should lead to an equivalent reduction in maximal instantaneous muscular power (W(p)) if the body segments' lengths remain unchanged. W(p) was determined during maximal jumps off both feet on a force platform before and on days 2, 6, 10, 32, and 48 after a 42-day duration BR. CSA of thigh muscles was measured by magnetic resonance imaging before and on day 5 after BR. Before BR, W(p) was 3.63 +/- 0.43 kW or 48.6 +/- 3.3 W/kg. On days 2 and 6 after BR, W(p) was reduced by 23.7 +/- 6.9 and 22.7 +/- 5.4% (P < 0.01), respectively. Thigh extensors CSA (CSAEXT) was 16.7 +/- 4.7% (P < 0.01) lower than before. When normalized per CSAEXT, W(p) was reduced by only 4.8 +/- 4.5% (P < 0.05). By day 48 of recovery, W(p) had returned to baseline values. Therefore, if W(p) is appropriately normalized for CSA of the extensor muscles, the reduction in CSAEXT explains most of the decrease in W(p) decrease after BR. Other factors such as a deficit in neural activation or a decrease in fiber-specific tension may account for only 5% of the W(p) loss after BR.

Plantar flexor activation capacity and H reflex in older adults: adaptations to strength training.

The purpose of this study was to investigate whether the voluntary neural drive and the excitability of the reflex arc could be modulated by training, even in old age. To this aim, the effects of a 16-wk strengthening program on plantar flexor voluntary activation (VA) and on the maximum Hoffman reflex (H(max))-to-maximum M wave (M(max)) ratio were investigated in 14 elderly men (65-80 yr). After training, isometric maximum voluntary contraction (MVC) increased by 18% (P < 0.05) and weight-lifting ability by 24% (P < 0.001). Twitch contraction time decreased by 8% (P < 0.01), but no changes in half relaxation time and in peak twitch torque were observed. The VA, assessed by twitch interpolation, increased from 95 to 98% (P < 0.05). Pretraining VA, also evaluated from the expected MVC for total twitch occlusion, was 7% higher (P < 0.01) than MVC. This discrepancy persisted after training. The interpolated twitch torque-voluntary torque relationship was fitted by a nonlinear model and was found to deviate from linearity for torque levels >65% MVC. Compared with younger men (24-35 yr), the H(max)- to M(max) ratio and nerve conduction velocity (H index) of the older group were significantly lower (42%, P < 0.05; and 29%, P < 0.001, respectively) and were not modulated by training. In conclusion, older men seem to preserve a high VA of plantar flexors. However, the impaired functionality of the reflex pathway with aging and the lack of modulation with exercise suggest that the decrease in the H(max)- to M(max) ratio and H index may be related to degenerative phenomena.

Effects of stride frequency on mechanical power and energy expenditure of walking.

The energetics and mechanics of walking were investigated at different speeds, both at the freely chosen stride frequency (FCSF) and at imposed ones (up to +/- 40% of FCSF). Metabolic energy expenditure was minimized at FCSF for each speed. Motion analysis allowed to calculate: the mechanical internal work rate (Wint), needed to move the segments with respect to the body center of mass (bcm); the external work rate (Wext), necessary to move bcm in the environment; and the total work rate (Wtot), equal to Wint+Wext. Wtot explains the metabolic optimization only at high speeds, while Wext, differently from previously reported, displays minima which better predict FCSF at all speeds (exception made for 1.39 m.s-1). This is probably caused by an overestimation of Wint due to a more ballistic movement of the limbs at low speeds (and low frequencies). The tendency of Wext to increase at high frequencies is due to a persistent minimal vertical excursion of bcm (about 0.02 m, the "locomotory dead space"). While the match between mechanics and energetics (at FCSF and imposed frequencies) occurs to a certain extent, it could be improved by removing the methodological assumptions about the energy transfer between segments and by the possibility to account for the coactivation of antagonist muscles.

A model equation for the prediction of mechanical internal work of terrestrial locomotion.

By refining a previously published model, a simple equation for the estimation of the mechanical internal work during locomotion is presented. The only input variables are the progression speed, the stride frequency and the duty factor, i.e. the fraction of the stride duration at which a foot is in contact with the ground. The inclusion of this last variable, easily measurable, allows to obtain a single equation for both walking and running. The model predictions have been compared with the mechanical internal work experimentally obtained on humans in several conditions: speeds (range 0.8-3.3 m s(-1)), gaits (walking and running) and gradients (+/-15%). The close match between the two indicates that the model equation can be used whenever a direct measurement of the mechanical internal work is unavailable.

A model for the estimation of visceral mass displacement in periodic movements.

This study suggests a method that, on the basis of concurrent cinematographic and dynamometric measurements, detects the motion of the visceral part of the body, provided that an estimate of its mass has been given in advance and the periodicity of the system dynamics can be assumed. The mathematical model provides equations for both vertical and horizontal displacements of the visceral mass, so that they can be used either separately or in combination to detect its one-, two- and three-dimensional trajectories. To test the model predictions, an external load has been periodically raised and lowered by a subject while standing on a dynamometric platform, and its vertical movement has been estimated accurately. A further experiment on hopping in place (without loads) reveals that the internal visceral mass (assumed equal to about 9 kg) oscillates out-of-phase with respect to the body frame, with a vertical range of about 0.05-0.08 m. A discussion on the possible sources of experimental inaccuracy is included. Also discussed are the applications of the model to work calculations in periodic movements as hopping, walking and running, as well as in investigations about locomotion-respiration coupling.

Spatial learning in rats exposed to acute ethanol intoxication on gestational day 8.

Pregnant Wistar rats were treated on gestational day 8 (GD 8) with two IP injections of either ethanol (2.9 g/kg in 24% v/v saline solution) or saline. Offspring were tested in the water-maze task at 45 or 90 days of age. The escape latencies of rats trained with a submerged escape platform at a fixed location were similar between control and experimental rats. Analyses of responses on a probe trial carried out 10 days after the training period, revealed that 90-day-old females prenatally exposed to alcohol were less likely to swim in the target region. No differences were observed in this free-swim trial in 45- and 90-day-old male, and 45-day-old female animals. Binding studies of low-affinity GABAA sites in the hippocampus showed an increase in affinity of [3H]GABAA for their binding sites in 90-day-old female offspring prenatally intoxicated with ethanol. Our results demonstrate that acute intoxication with ethanol on GD 8 did not modify acquisition but impaired the retention of spatial learning only in adult female rats. It is possible that the impaired retention will be consequence of higher GABAA receptor affinity.

[Interest in intestinal resection for treatment of advanced ovarian cancer]. / Intérêt des exérèses digestives dans le traitement des cancers évolués de l'ovaire.

AIM OF THE STUDY: Digestive surgery is often necessary for surgical management of advanced ovarian carcinoma. PATIENTS AND METHODS: In a series of 62 patients with stage III ovarian carcinoma, postoperative morbidity and mortality, overall survival after 5 years and disease-free survival after 2 years were studied and corelated with several patients criteria (age, stage of the disease, residual disease, type of surgery, CA125 normalisation delay, postoperative complications and hospital stay). Patients were divided into two groups according to the surgical treatment. The first group (n = 17) included patients treated by gynecologic and digestive surgery, the second group (n = 45) included patients treated by gynecologic surgery only. All patients were proposed for chemotherapy included platyn salt. Mean age was 60 years (range: 20-83). The stage of the cancer was stage IIIa in 7 cases, stage IIIb in ten and stage IIIc in 45. RESULTS: Postoperative mortality was 3.5% (2/62). Postoperative morbidity was 26% (13/62). No statistical differences were noted for hospital stay, general morbidity, surgical morbidity when a gastric resection or a colon resections or a splenectomy were performed. Overall survival at 5 years was 56%. Residual disease less than 2 cm3 is the only prognostic factor for overall survival (56% vs 23% [P = 0.03]) and disease-free survival (86% vs 46% [P = 0.02]). CONCLUSION: This study including 62 patients confirmed the prognostic significance of extensive cytoreductive surgery for treatment in advanced ovarian epithelial cancer without increasing the postoperative morbidy and mortality.

Invariant aspects of human locomotion in different gravitational environments.

Previous literature showed that walking gait follows the same mechanical paradigm, i.e. the straight/inverted pendulum, regardless the body size, the number of legs, and the amount of gravity acceleration. The Froude number, a dimensionless parameter originally designed to normalize the same (pendulum-like) motion in differently sized subjects, proved to be useful also in the comparison, within the same subject, of walking in heterogravity. In this paper the theory of dynamic similarity is tested by comparing the predictive power of the Froude number in terms of walking speed to previously published data on walking in hypogravity simulators. It is concluded that the Froude number is a good first predictor of the optimal walking speed and of the transition speed between walking and running in different gravitational conditions. According to the Froude number a dynamically similar walking speed on another planet can be calculated as [formula: see text] where V(Earth) is the reference speed on Earth.

The velo-uvulo-pharyngeal lift or "roman blinds" technique for treatment of snoring: a preliminary report.

Snoring is caused by vibrating anatomical structures in the upper aerodigestive tract. It can be treated surgically and non-surgically, although resective procedures are associated with high postoperative morbidity and failure rate. We describe a new non-resective surgical procedure called the velo-uvulo-pharyngeal lift in which the soft palate is lifted, shortened, advanced and stiffened by means of permanent threads anchored to fibro-osseous attachments at the level of the posterior nasal spine and both pterygoid hamuli. Four adult patients (median age 44.5 years; range 42-65) affected by snoring and mild obstructive sleep apnoea-hypopnoea syndrome (apneoa-hypopnoea index, AHI < 20) requiring septal surgery under general anesthesia also underwent velo-uvulo-pharyngeal lift. There were no significant intra- or post-operative complications, and all of the patients reported immediate snoring relief. The main complaints were slight pain and a sensation of local fullness, both of which spontaneously disappeared within two days. The subjective clinical improvement in snoring was confirmed during post-operative follow-up (median 15.5 months; range 6-25), as was the stable reshaping of the soft velo-uvulo-pharyngeal tissues and enlargement of the mesopharyngeal space. There was also a decrease in daytime sleepiness. Our preliminary results suggest that velo-uvulo-pharyngeal lift is a simple, cost-effective and minimally invasive means of widening the mesopharyngeal space in snoring patients with or without mild sleep apnoea-hypopnoea syndrome. The widening of the mesopharyngeal space prevents contact-induced wall vibrations and its inspiratory obstruction causing hypopnoea and apnoea. It can also be combined with other procedures if indicated.