Mechanisms underlying center of pressure displacements in obese subjects during quiet stance.

OBJECTIVE: the aim of this study was to assess whether reduced balance capacity in obese subjects is secondary to altered sensory information. DESIGN: cross sectional study. SUBJECTS: 44 obese (BMI = 40.6 ± 4.6 kg/m2, age = 34.2 ± 10.8 years, body weight: 114,0 ± 16,0 Kg, body height 167,5 ± 9,8 cm) and 20 healthy controls (10 females, 10 males, BMI: 21.6 ± 2.2 kg/m2, age: 30.5 ± 5.5 years, body weight: 62,9 ± 9,3 Kg, body height 170,1 ± 5,8 cm) were enrolled. MEASUREMENTS: center of pressure (CoP) displacements were evaluated during quiet stance on a force platform with eyes open (EO) and closed (EC). The Romberg quotient (EC/EO) was computed and compared between groups. RESULTS: we found statistically significant differences between obese and controls in CoP displacements (p < 0.01) and no statistically significant differences in Romberg quotients (p > 0.08). CONCLUSION: the increased CoP displacements in obese subjects do not need an hypothesis about altered sensory information. The integration of different sensory inputs appears similar in controls and obese. In the latter, the increased mass, ankle torque and muscle activity may probably account for the higher CoP displacements.

Effect of obesity and low back pain on spinal mobility: a cross sectional study in women.

BACKGROUND: obesity is nowadays a pandemic condition. Obese subjects are commonly characterized by musculoskeletal disorders and particularly by non-specific chronic low back pain (cLBP). However, the relationship between obesity and cLBP remains to date unsupported by an objective measurement of the mechanical behaviour of the spine and its morphology in obese subjects. Such analysis may provide a deeper understanding of the relationships between function and the onset of clinical symptoms. PURPOSE: to objectively assess the posture and function of the spine during standing, flexion and lateral bending in obese subjects with and without cLBP and to investigate the role of obesity in cLBP. STUDY DESIGN: Cross-sectional study PATIENT SAMPLE: thirteen obese subjects, thirteen obese subjects with cLBP, and eleven healthy subjects were enrolled in this study. OUTCOME MEASURES: we evaluated the outcome in terms of angles at the initial standing position (START) and at maximum forward flexion (MAX). The range of motion (ROM) between START and MAX was also computed. METHODS: we studied forward flexion and lateral bending of the spine using an optoelectronic system and passive retroreflective markers applied on the trunk. A biomechanical model was developed in order to analyse kinematics and define angles of clinical interest. RESULTS: obesity was characterized by a generally reduced ROM of the spine, due to a reduced mobility at both pelvic and thoracic level; a static postural adaptation with an increased anterior pelvic tilt. Obesity with cLBP is associated with an increased lumbar lordosis.In lateral bending, obesity with cLBP is associated with a reduced ROM of the lumbar and thoracic spine, whereas obesity on its own appears to affect only the thoracic curve. CONCLUSIONS: obese individuals with cLBP showed higher degree of spinal impairment when compared to those without cLBP. The observed obesity-related thoracic stiffness may characterize this sub-group of patients, even if prospective studies should be carried out to verify this hypothesis.

Strength characterization of knee flexor and extensor muscles in Prader-Willi and obese patients.

BACKGROUND: despite evidence of an obesity-related disability, there is a lack of objective muscle functional data in overweight subjects. Only few studies provide instrumental strength measurements in non-syndromal obesity, whereas no data about Prader-Willi syndrome (PWS) are reported. The aim of our study was to characterize the lower limb muscle function of patients affected by PWS as compared to non-syndromal obesity and normal-weight subjects. METHODS: We enrolled 20 obese (O) females (age: 29.1 +/- 6.5 years; BMI: 38.1 +/- 3.1), 6 PWS females (age: 27.2 +/- 4.9 years; BMI: 45.8 +/- 4.4) and 14 healthy normal-weight (H) females (age: 30.1 +/- 4.7 years; BMI: 21 +/- 1.6). Isokinetic strength during knee flexion and extension in both lower limbs at the fixed angular velocities of 60 degrees /s, 180 degrees /s, 240 degrees /s was measured with a Cybex Norm dynamometer. RESULTS: the H, O and PWS populations appear to be clearly stratified with regard to muscle strength.: PWS showed the lowest absolute peak torque (PT) for knee flexor and extensor muscles as compared to O (-55%) and H (-47%) (P = 0.00001). O showed significantly higher strength values than H as regard to knee extension only (P = 0.0014). When strength data were normalised by body weight, PWS showed a 50% and a 70% reduction in PT as compared to O and H, respectively. Knee flexors strength values were on average half of those reported for extension in all of the three populations. CONCLUSION: the novel aspect of our study is the determination of objective measures of muscle strength in PWS and the comparison with O and H patients. The objective characterization of muscle function performed in this study provides baseline and outcome measures that may quantify specific strength deficits amendable with tailored rehabilitation programs and monitor effectiveness of treatments.

Walking in an immersive virtual reality.

The aim of this study was to investigate the effects on gait induced by a completely immersive Virtual Reality (VR) with and without perturbation. Ten healthy subjects were analyzed during over-ground walking in different conditions: standard gait, VR gait and perturbed VR gait. Results showed that subjects immersed in the virtual environment walked slowly, with decreased cadence (-13%) and stride length (-28%) as well as increased base of support in terms of step width (+20%). The perturbation of the VR caused an interesting effect: many computed parameters, still away from the standard gait condition, improved if compared to the unperturbed VR condition. In conclusion, walking in VR leads to gait instability, which is less pronounced in presence of perturbation, probably due to the reweight of sensory inputs. This study could represent the first step for the application of the proposed VR environment to pathological subjects.

Virtual reality for the upper limb motor training in stroke: a case report.

In this report we describe the effects of a virtual reality (VR) training addressed to the upper limb of a stroke patient. After 20 days of rehabilitation sessions consisting of physical therapy and VR rehabilitation, the subject was evaluated by means of kinematics and clinical scales. Results showed the improvement of paretic arm mobility, in terms of quantitative parameters and clinical scales, suggesting that VR training could represent a valuable tool to supplement the traditional rehabilitation provided by the physical therapist.

Behaviour of motor disabilities and appearance of visual hallucinations in patients with Parkinson's disease in a virtual environment.

We studied 23 Parkinson's disease (PD) non-demented patients and 15 controls in Virtual Reality (VR) environments reproducing usual daily living situations. In VR sessions, PD patients performed their actions worse than controls, in terms of time of execution in exploration and pointing, precision as objects avoiding, and in semantic incidental memory task. We observed clear differences of performances between on and off status medication, with a global worsening during off phase. Moreover, all six patients with motor fluctuations described visual hallucinations during off state, with occurrence of images not included in the virtual environment.

Lactase non-persistent genotype distribution in Italy.

BACKGROUND: Adult-type hypolactasia is a frequent condition of lactose malabsorption; in Europe the distribution of adult-type hypolactasia have been shown to display a North-South gradient. Genotyping for LCT-13910 C>T polymorphism has been proposed as a useful diagnostic marker of adult-type hypolactasia. Data concerning lactase non-persistent genotype distribution in Italy are confused and not well characterized. The aim of this study was to determine the prevalence of CC-genotype corresponding to lactase non-persistence in Italian population. METHODS: We genotyped 1312 adult Italian subjects for LCT-13910 C>T polymorphism by KASPar chemistry (KBioscience Ltd., Hoddesdon, England, UK). RESULTS: The frequency of the lactase non-persistence genotype of our sample was 62.3% that was higher than the values published for adult hypolactasia in Italy. In our study a frequency of 58.6%, 74.1% and 67.1% was detected in the three main macro-regions of Italy (North, Center, and South), respectively. CONCLUSIONS: For the first time we analyzed the distribution of the LCT-13910 CC genotype in a big population of Italian subjects. Our data did not validate the presence of a North-South gradient for adult hypolactasia along the Italian peninsula.

A 3D interactive multimodal viewer as data mining tool for the Visible Human Dataset color image histograms.

An on-line virtual three-dimensional immersive environment to navigate through colorimetric characterization of the Visible Human Dataset (VHD) cryosectional cross-section color images is introduced. Real-time analysis of color component characteristics of a user defined set of VHD images is now possible. This is a potentially useful resource to many developers working on the VHD raw data, however it could be used in medical education.

Effect of obesity onset on pendular energy transduction at spontaneous walking speed: Prader-Willi versus nonsyndromal obese individuals.

OBJECTIVE: To compare the mechanical external work (Wext ) and pendular energy transduction (Rstep ) at spontaneous walking speed (Ss ) in individuals with Prader-Willi syndrome (PWS) versus subjects with nonsyndromal obesity (OB) to investigate whether the early onset of obesity allows PWS subjects to adopt energy conserving gait mechanics. DESIGN AND METHODS: Wext and Rstep were computed using kinematic data acquired by an optoelectronic system and compared in 15 PWS (BMI = 39.5 ± 1.8 kg m(-2) ; 26.7 ± 1.5 year) and 15 OB (BMI = 39.3 ± 1.0 kg m(-2) ; 28.7 ± 1.9 year) adults matched for gender, age and BMI and walking at Ss . RESULTS: Ss was significantly lower in PWS (0.98 ± 0.03 m s(-1) ) than in OB (1.20 ± 0.02 m s(-1) ; P < 0.001). There were no significant differences in Wext per kilogram between groups (PWS: 0.37 ± 0.04 J kg(-1) m(-1) ; OB: 0.40 ± 0.05 J kg(-1) m(-1) ; P = 0.66) and in Rstep (PWS: 69.9 ± 2.9%; OB: 67.7 ± 2.4%; P = 0.56). However, Rstep normalized to Froude number (Rstep /Fr) was significantly greater in PWS (6.0 ± 0.6) than in OB (3.8 ± 0.2; P = 0.001). Moreover, Rstep /Fr was inversely correlated with age of obesity onset (r = -0.49; P = 0.006) and positively correlated with obesity duration (r = 0.38; P = 0.036). CONCLUSION: Individuals with PWS seem to alter their gait to improve pendular energy transduction as a result of precocious and chronic adaptation to loading.

Effects of tiotropium and formoterol on quiet breathing pattern assessed by optoelectronic plethysmography in COPD patients: a pilot study.

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) is a disease characterized by an airflow limitation that is not fully reversible. ß(2)-agonists and anticholinergics represent the most effective therapeutic options. Optoelectronic plethysmography (OEP) is a novel technology, which provides noninvasive steady-state measurements of chest wall kinematics, together with the assessment of the relative contribution of all different thoracic and abdominal compartments to tidal volume. OBJECTIVES: The aim of this pilot study was to investigate the changes in quiet breathing due to different long-acting bronchodilators (namely, formoterol and tiotropium) administered to COPD patients of different severity. METHODS: Eight moderate-to-severe COPD patients were studied according to a randomized crossover design. All subjects received both the long-acting bronchodilators: formoterol (long-acting ß(2)-agonist, 24 µg) and tiotropium (long-acting anticholinergic bronchodilator, 18 µg). The effect of bronchodilators on quiet breathing was evaluated by means of OEP at base conditions, and 2 and 7 hours after inhalation. RESULTS: Both bronchodilators caused changes in the quiet breathing pattern in COPD patients that had previously reported only negligible changes in FEV(1) (ΔFEV(1) = 2.6% after salbutamol). The main changes were observed in increased ventilation per minute, inspiratory and expiratory flow, and decreased breath-by-breath variability. Formoterol induced its main effects during the first 2 hours after inhalation, while tiotropium caused improvements between 2 and 7 hours. CONCLUSION: Even though a greater cohort of COPD patients is needed in order to confirm the present results, this pilot study reports a novel piece of evidence concerning the effects of bronchodilators on quiet breathing pattern in severe and very severe COPD patients.

Gait pattern in myotonic dystrophy (Steinert disease): a kinematic, kinetic and EMG evaluation using 3D gait analysis.

We investigated the gait pattern of 10 patients with myotonic dystrophy (Steinert disease; 4 females, 6 males; age: 41.5+7.6 years), compared to 20 healthy controls, through manual muscle test and gait analysis, in terms of kinematic, kinetic and EMG data. In most of patients (80%) distal muscle groups were weaker than proximal ones. Weakness at lower limbs was in general moderate to severe and MRC values evidenced a significant correlation between tibialis anterior and gastrocnemius medialis (R=0.91). An overall observation of gait pattern in patients when compared to controls showed that most spatio-temporal parameters (velocity, step length and cadence) were significantly different. As concerns kinematics, patients' pelvic tilt was globally in a higher position than control group, with reduced hip extension ability in stance phase and limited range of motion; 60% of the limbs revealed knee hyperextension during midstance and ankle joints showed a quite physiological position at initial contact and higher dorsiflexion during stance phase if compared to healthy individuals. Kinetic plots evidenced higher hip power during loading response and lower ankle power generation in terminal stance. The main EMG abnormalities were seen in tibialis anterior and gastrocnemius medialis muscles. In this study gait analysis gives objective and quantitative information about the gait pattern and the deviations due to the muscular situation of these patients; these results are important from a clinical point of view and suggest that rehabilitation programs for them should take these findings into account.

Osteopathic manipulative treatment in obese patients with chronic low back pain: a pilot study.

BACKGROUND: Obesity is frequently associated with various musculoskeletal disorders including chronic low back pain (cLBP). Osteopathy is a discipline emphasizing the conservative treatment of the disease in an olistic vision. We designed a randomized controlled study to investigate whether Osteopathic Manipulative Treatment (OMT) combined with specific exercises (SE) is more effective than SE alone in obese patients with cLBP. METHODS: nineteen obese females with cLBP, randomized into 2 groups: SE + OMT and SE were studied during the forward flexion of the spine using an optoelectronic system. A biomechanical model was developed in order to analyse kinematics and define angles of clinical interest. OUTCOME MEASURES: kinematic of the thoracic and lumbar spine and pelvis during forward flexion, pain according to a visual analogue scale (VAS), Roland Morris Disability Questionnaire and Oswestry Low Back Pain Disability Questionnaire. RESULTS: significant effects on kinematics were reported only for OMT + SE with an improvement in thoracic range of motion of nearly 20%. All scores of the clinical scales used improved significantly. The greatest improvements occurred in the OMT + SE group. CONCLUSIONS: combined rehabilitation treatment including Osteopathic Manipulative Treatment (OMT + SE) showed to be effective in improving biomechanical parameters of the thoracic spine in obese patients with cLBP. Such results are to be attributed to OMT, since they were not evident in the SE group. We also observed a reduction of disability and pain. The clinical results should be considered preliminary due to the small sample size.

Characterisation of balance capacity in Prader-Willi patients.

Being severely overweight is a distinctive clinical feature of Prader-Willi Syndrome (PWS). This explorative study aims to characterise balance capacity in PWS as compared to non-genetically obese patients (O) and to a group of normal-weight individuals (CG). We enrolled 14 PWS patients: 8 females and 6 males (BMI = 41.3 ± 7.3 kg/m(2), age = 32.86+4.42 years), 44 obese individuals, 22 males and 22 females (BMI = 40.6 ± 4.6 kg/m(2), age = 34.2 ± 10.7 years) and 20 controls (CG: 10 females and 10 males; BMI: 21.6 ± 1.6 kg/m(2); age: 30.5 ± 5.3 years). Postural acquisitions were conducted by means of a force platform from which the COP pattern vs time was analysed. The participants were required to stand barefoot on the platform with eyes open and heels at standardized distance and position for 60s. All of the analysed parameters were statistically different from O and CG groups. PWS individuals showed greater displacements in both the A/P and M/L direction (RMS, RANGE and MV indices). Analysis of the overall planar movement of the CoP showed that the PWS patients were characterised by higher RMS distance from the centre (RMS(CoP) index) and area of confidence ellipse (AREA(CoP) index) when compared both to obese and healthy individuals. PWS patients showed a poorer balance capacity than their non-genetically obese counterparts and healthy individuals, with greater differences in both the A/P and M/L direction than O. Rehabilitation programs for PWS should take this finding into account. In addition to weight loss, strengthening of ankle flexors/extensors, and balance training, tailored interventions aimed at improving A/P control should be given particular consideration.

Mechanical external work and recovery at preferred walking speed in obese subjects.

PURPOSE: The aim of this study was to compare the mechanical external work (per kg) and pendular energy transduction at preferred walking speed (PWS) in obese versus normal body mass subjects to investigate whether obese adults adopt energy conserving gait mechanics. METHODS: The mechanical external work (Wext) and the fraction of mechanical energy recovered by the pendular mechanism (Rstep) were computed using kinematic data acquired by an optoelectronic system and were compared in 30 obese (OG; body mass index [BMI] = 39.6 +/- 0.6 kg m(-2); 29.5 +/- 1.3 yr) and 19 normal body mass adults (NG; BMI = 21.4 +/- 0.5 kg m(-2); 31.2 +/- 1.2 yr) walking at PWS. RESULTS: PWS was significantly lower in OG (1.18 +/- 0.02 m s(-1)) than in NG (1.33 +/- 0.02 m s(-1); P

Gender-specific effect of obesity on balance.

Obesity modifies the body geometry by adding mass to different regions and it influences the biomechanics of activities of daily living. Weight influences postural stability, but there is no consensus as to whether the different fat distribution in males and females produces gender-related effects on balance. The aim of this study was to investigate the effect of body weight increases on postural performance in males and females. A total of 22 obese females (BMI: 41.1+/-4.1 kg/m2) and 22 obese males (BMI: 40.2+/-5 kg/m2) were analyzed during a static posture trial on a force platform in standardized conditions. Twenty healthy subjects (10 females, 10 males) constituted the control group. We computed the following parameters related to the center of pressure (CoP): velocity and displacements along the antero-posterior (AP) and medio-lateral axis (ML). We found several statistically significant differences between healthy and obese men, in particular regarding the AP and ML CoP parameters, which were correlated to body weight (r=0.36-0.58). The comparison between healthy and obese females pointed out statistically significant differences in AP parameters and no significant differences in ML displacements. Body weight was found to correlate with AP parameters (r=0.36-0.74), but not with ML displacements. The increased body mass seems to produce AP instability in both genders and ML destabilization only in males. Rehabilitation programs should take these findings into account by adopting specific interventions to improve ML control in obese males, and through weight loss and strengthening of ankle flexors/extensors in both genders.

A web management service applied to a comprehensive characterization of Visible Human Dataset colour images.

Visible Human Dataset (VHD) is a remarkable piece of raw digital anatomical knowledge still to be fully exploited. Colours of VHD anatomic images are the natural targets of different algorithmic approaches devoted to understanding the content of the complex digital medical images, but they have never been analysed exhaustively. A full colorimetric characterization of all 9000 VHD colour images may help to take advantage of implicit available information in raw data. This study describes a novel colorimetric characterization and a Visual Knowledge Discovery tool, using methods from database field, data visualization, and image analysis. The applied heterogeneous methods allowed us to develop a histogram meta database and make it available remotely. It consists of a histogram-based colorimetric characterization of the all VHD 24-bit colour images. A user-friendly, interactive, and intuitive 3D framework providing 3D services was built and made freely available. It allows real-time analysis of colour component characteristics of a user-defined set of VHD images providing 3D interactive navigation of the histogram meta database. New knowledge can be discovered using our tool and the histogram meta database provided. This work allowed us to propose novel methods for colour image characterization and obtained results using developed service on VHD colour images let us to partially understand the not fully satisfactorily results achieved so far analysing these images.

A colorimetric characterization of the raw digital data of the Visible Human Dataset images.

A colorimetric characterization of the all about 9 thousand Visible Human Dataset (VHD) cryosectioned color images of the male and female body is described here. Such characterization is performed keeping limited the computational time besides the high resolution of the considered VHD images. The about 27 thousand distinct histograms obtained are downloadable from the VHD Milano Mirror Site ftp server.