Femoroacetabular impingement: normal values of the quantitative morphometric parameters in asymptomatic hips.

OBJECTIVE: To determine the means and the reference intervals of the quantitative morphometric parameters of femoroacetabular impingement (FAI) in normal hips with high-resolution computed tomography (CT). METHODS: We prospectively included 94 adult individuals who underwent CT for thoracic, abdominal or urologic pathologies. Patients with a clinical history of hip pathology and/or with osteoarthritis on CT were excluded. We calculated means and 95 % reference intervals for imaging signs of cam-type (alpha angle at 90° and 45° and femoral head-neck offset) and pincer-type impingement (acetabular version angle, lateral centre-edge angle and acetabular index). RESULTS: The 95 % reference interval limits were all far beyond the abnormal thresholds found in the literature for cam-type and to a lesser extent for pincer-type FAI. The upper limits of the reference intervals for the alpha angles (at 90°/45°) were 68°/83° (men) and 69°/84° (women), compared to thresholds from the literature (50°, 55° or 60°). Reference intervals were similar between genders for cam-type parameters, and slightly differed for pincer-type. CONCLUSION: The 95 % reference intervals of morphometric measurements of FAI in asymptomatic hips were beyond the abnormal thresholds, which was especially true for cam-type FAI. Our results suggest the need for redefining the current morphometric parameters used in the diagnosis of FAI. KEY POINTS: ? 95 % reference intervals limits of FAI morphotype were beyond currently defined thresholds. ? Reference intervals of pincer-type morphotype measurements were close to current definitions. ? Reference intervals of cam-type morphotype measurements were far beyond the current definitions. ? Current morphometric definitions of cam-type morphotype should be used with care.

GPS analysis of human locomotion: further evidence for long-range correlations in stride-to-stride fluctuations of gait parameters.

During free walking, gait is automatically adjusted to provide optimal mechanical output and minimal energy expenditure; gait parameters, such as cadence, fluctuate from one stride to the next around average values. It was described that this fluctuation exhibited long-range correlations and fractal-like patterns. In addition, it was suggested that these long-range correlations disappeared if the participant followed the beep of metronome to regulate his or her pace. Until now, these fractal fluctuations were only observed for stride interval, because no technique existed to adequately analyze an extended time of free walking. The aim of the present study was to measure walking speed (WS), step frequency (SF) and step length (SL) with high accuracy (<1 cm) satellite positioning method (global positioning system or GPS) in order to detect long-range correlations in the stride-to-stride fluctuations. Eight participants walked 30 min under free and constrained (metronome) conditions. Under free walking conditions, DFA (detrended fluctuation analysis) and surrogate data tests showed that the fluctuation of WS, SL and SF exhibited a fractal pattern (i.e., scaling exponent alpha: 0.5 < alpha < 1) in a large majority of participants (7/8). Under constrained conditions (metronome), SF fluctuations became significantly anti-correlated (alpha < 0.5) in all participants. However, the scaling exponent of SL and WS was not modified. We conclude that, when the walking pace is controlled by an auditory signal, the feedback loop between the planned movement (at supraspinal level) and the sensory inputs induces a continual shifting of SF around the mean (persistent anti-correlation), but with no effect on the fluctuation dynamics of the other parameters (SL, WS).

How useful is satellite positioning system (GPS) to track gait parameters? A review.

Over the last century, numerous techniques have been developed to analyze the movement of humans while walking and running. The combined use of kinematics and kinetics methods, mainly based on high speed video analysis and forceplate, have permitted a comprehensive description of locomotion process in terms of energetics and biomechanics. While the different phases of a single gait cycle are well understood, there is an increasing interest to know how the neuro-motor system controls gait form stride to stride. Indeed, it was observed that neurodegenerative diseases and aging could impact gait stability and gait parameters steadiness. From both clinical and fundamental research perspectives, there is therefore a need to develop techniques to accurately track gait parameters stride-by-stride over a long period with minimal constraints to patients. In this context, high accuracy satellite positioning can provide an alternative tool to monitor outdoor walking. Indeed, the high-end GPS receivers provide centimeter accuracy positioning with 5-20 Hz sampling rate: this allows the stride-by-stride assessment of a number of basic gait parameters--such as walking speed, step length and step frequency--that can be tracked over several thousand consecutive strides in free-living conditions. Furthermore, long-range correlations and fractal-like pattern was observed in those time series. As compared to other classical methods, GPS seems a promising technology in the field of gait variability analysis. However, relative high complexity and expensiveness--combined with a usability which requires further improvement--remain obstacles to the full development of the GPS technology in human applications.

Sedation and analgesia for colonoscopy: patient tolerance, pain, and cardiorespiratory parameters.

BACKGROUND: Colonoscopy is generally performed with the patient sedated and receiving analgesics. However, the benefit of the most often used combination of intravenous midazolam and pethidine on patient tolerance and pain and its cardiorespiratory risk have not been fully defined. METHODS: In this double-blind prospective study, 150 outpatients undergoing routine colonoscopy were randomly assigned to receive either (1) low-dose midazolam (35 micrograms/kg) and pethidine (700 micrograms/kg in 48 patients, 500 micrograms/kg in 102 patients), (2) midazolam and placebo pethidine, or (3) pethidine and placebo midazolam. RESULTS: Tolerance (visual analog scale, 0 to 100 points: 0 = excellent; 100 = unbearable) did not improve significantly more in group 1 compared with group 2 (7 points; 95% confidence interval [-2-17]) and group 3 (2 points; 95% confidence interval [-7-12]). Similarly, pain was not significantly improved in group 1 as compared with the other groups. Male gender (p < 0.001) and shorter duration of the procedure (p = 0.004), but not amnesia, were associated with better patient tolerance and less pain. Patient satisfaction was similar in all groups. Oxygen desaturation and hypotension occurred in 33% and 11%, respectively, with a similar frequency in all three groups. CONCLUSIONS: In this study, the combination of low-dose midazolam and pethidine does not improve patient tolerance and lessen pain during colonoscopy as compared with either drug given alone. When applying low-dose midazolam, oxygen desaturation and hypotension do not occur more often after combined use of both drugs. For the individual patient, sedation and analgesia should be based on the endoscopist's clinical judgement.

A template-assembled synthetic protein surface mimetic of the von Willebrand factor A1 domain inhibits botrocetin-induced platelet aggregation.

Platelet adhesion, the initial step of platelet activation, is mediated by the interaction of von Willebrand factor (VWF) with its platelet receptor, the GPIb-IX complex. The binding of VWF to GPIb-IX is induced either by increased shear stress or by exogenous modulators, such as botrocetin. At a molecular level, this interaction takes place between the A1 domain of VWF and the GPIb alpha chain of the GPIb-IX complex. We report here the design and functional characteristics of a VWF template-assembled synthetic protein (TASP), a chimeric four-helix-bundle TASP scaffold mimicking the surface of the A1 domain. Twelve residues located on helices alpha 3 and alpha 4 in the native A1 domain were grafted onto a surface formed by two neighboring helices of the TASP. VWF TASP was found to inhibit specifically botrocetin-induced platelet aggregation and to bind both botrocetin and GPIb alpha. However, in contrast to the native A1 domain, VWF TASP did not bind simultaneously to both ligands. Modeling studies revealed that the relative orientation of the alpha helices in VWF TASP led to a clash of bound botrocetin and GPIb alpha. These results demonstrate that a chimeric four-helix-bundle TASP as a scaffold offers a suitable surface for presenting crucial residues of the VWF A1 domain; the potential of the TASP approach for de novo protein design and mimicry is thereby illustrated.

Diagnostic value of vestibulo-ocular reflex parameters in the detection and characterization of labyrinthine lesions.

OBJECTIVE: To evaluate the power of various parameters of the vestibulo-ocular reflex (VOR) in detecting unilateral peripheral vestibular dysfunction and in characterizing certain inner ear pathologies. STUDY DESIGN: Prospective study of consecutive ambulatory patients presenting with acute onset of peripheral vertigo and spontaneous nystagmus. SETTING: Tertiary referral center. PATIENTS: Seventy-four patients (40 females, 34 males) and 22 normal subjects (11 females, 11 males) were included in the study. Patients were classified in three main diagnoses: vestibular neuritis: 40; viral labyrinthitis: 22; Meniere's disease: 12. METHODS: The VOR function was evaluated by standard caloric and impulse rotary tests (velocity step). A mathematical model of vestibular function was used to characterize the VOR response to rotational stimulation. The diagnostic value of the different VOR parameters was assessed by uni- and multivariable logistic regression. RESULTS: In univariable analysis, caloric asymmetry emerged as the most powerful VOR parameter in identifying unilateral vestibular deficit, with a boundary limit set at 20%. In multivariable analysis, the combination of caloric asymmetry and rotational time constant asymmetry significantly improved the discriminatory power over caloric alone (p&lt;0.0001) and produced a detection score with a correct classification of 92.4%. In discriminating labyrinthine diseases, different combinations of the VOR parameters were obtained for each diagnosis (p&lt;0.003) supporting that the VOR characteristics differ between the three inner ear disorders. However, the clinical usefulness of these characteristics in separating the pathologies was limited. CONCLUSION: We propose a powerful logistic model combining the indices of caloric and time constant asymmetries to detect a peripheral vestibular loss, with an accuracy of 92.4%. Based on vestibular data only, the discrimination between the different inner ear diseases is statistically possible, which supports different pathophysiologic changes in labyrinthine pathologies.

Formule sanguine: intérêt des nouveaux paramètres [Complete blood counts: new parameters].

Performing a complete blood count analysis is a daily routine necessary for a good care of patients. Nowadays, modern blood analyzers provide on top of classical blood values, several additional parameters. In this paper, using short case presentations, we discuss how to interpret these results and integrate them in the clinical context.

Bacterial contamination of platelet concentrates: pathogen detection and inactivation methods

Whereas the reduction of transfusion related viral transmission has been a priority during the last decade, bacterial infection transmitted by transfusion still remains associated to a high morbidity and mortality, and constitutes the most frequent infectious risk of transfusion. This problem especially concerns platelet concentrates because of their favorable bacterial growth conditions. This review gives an overview of platelet transfusion-related bacterial contamination as well as on the different strategies to reduce this problem by using either bacterial detection or inactivation methods.

Correlations between trabecular bone score, measured using anteroposterior dual-energy x-ray absorptiometry acquisition, and 3-dimensional parameters of bone microarchitecture: an experimental study on human cadaver vertebrae.

Developing a novel technique for the efficient, noninvasive clinical evaluation of bone microarchitecture remains both crucial and challenging. The trabecular bone score (TBS) is a new gray-level texture measurement that is applicable to dual-energy X-ray absorptiometry (DXA) images. Significant correlations between TBS and standard 3-dimensional (3D) parameters of bone microarchitecture have been obtained using a numerical simulation approach. The main objective of this study was to empirically evaluate such correlations in anteroposterior spine DXA images. Thirty dried human cadaver vertebrae were evaluated. Micro-computed tomography acquisitions of the bone pieces were obtained at an isotropic resolution of 93μm. Standard parameters of bone microarchitecture were evaluated in a defined region within the vertebral body, excluding cortical bone. The bone pieces were measured on a Prodigy DXA system (GE Medical-Lunar, Madison, WI), using a custom-made positioning device and experimental setup. Significant correlations were detected between TBS and 3D parameters of bone microarchitecture, mostly independent of any correlation between TBS and bone mineral density (BMD). The greatest correlation was between TBS and connectivity density, with TBS explaining roughly 67.2% of the variance. Based on multivariate linear regression modeling, we have established a model to allow for the interpretation of the relationship between TBS and 3D bone microarchitecture parameters. This model indicates that TBS adds greater value and power of differentiation between samples with similar BMDs but different bone microarchitectures. It has been shown that it is possible to estimate bone microarchitecture status derived from DXA imaging using TBS.

Influence of the timing of low-dose aspirin on tolerability of prolonged-release nicotinic acid in patients at elevated cardiovascular risk

OBJECTIVES: To investigate the effect of low-dose aspirin administered in the morning or evening on the rate of discontinuation of prolonged-release nicotinic acid (Niaspan) due to flushing in patients at elevated cardiovascular risk. RESEARCH DESIGN AND METHODS: This was an observational, non-interventional study in patients at elevated cardiovascular risk due to cardiovascular disease or type 2 diabetes. Patients received prolonged-release nicotinic acid and aspirin under the usual care of their physician for 15 weeks. MAIN OUTCOME MEASURES: The main outcome measure was the rate of treatment discontinuation for flushing. Other adverse drug reactions (ADRs) were also recorded. Lipid parameters were also measured. RESULTS: The patient population included 539 subjects (70% male); 36% had type 2 diabetes, 80% had prior cardiovascular disease, and 37% had a family history of cardiovascular disease. The rate of treatment discontinuation due to flushing did not differ (p = 0.3375) between the morning aspirin group (10.6%) and the evening aspirin group (13.8%). The overall incidence of flushing was 57%. Most flushes were of mild or moderate severity and decreases occurred over time in both frequency and intensity. ADRs unrelated to flushing occurred in 6.6% of the morning aspirin group and 7.4% of the evening aspirin group. HDL-cholesterol increased by +21.3% in the overall population, together with moderate improvements in other lipid parameters. CONCLUSIONS: Flushing was the most common ADR with prolonged-release nicotinic acid treatment, as expected. The timing of aspirin administration did not influence the rate of treatment discontinuations for flushing. Marked increases in HDL-cholesterol were observed.

Validation of rotational thromboelastometry during cardiopulmonary bypass: A prospective, observational in-vivo study.

BACKGROUND: Rotational thromboelastometry (ROTEM) is a whole blood point-of-test used to assess the patient's coagulation status. Three of the available ROTEM tests are EXTEM, INTEM and HEPTEM. In the latter, heparinase added to the INTEM reagent inactivates heparin to reveal residual heparin effect. Performing ROTEM analysis during cardiopulmonary bypass (CPB) might allow the anaesthesiologist to anticipate the need for blood products. OBJECTIVE: The goal of this study was to validate ROTEM analysis in the presence of very high heparin concentrations during CPB. DESIGN: Prospective, observational trial. SETTING: Single University Hospital. PARTICIPANTS: Twenty patients undergoing coronary artery bypass grafting. MAIN OUTCOME MEASURE: ROTEM analysis was performed before heparin administration (T0), 10 min after heparin (T1), at the end of CPB (T2) and 10 min after protamine (T3). The following tests were performed: EXTEM, INTEM, and HEPTEM. Heparin concentrations were measured at T1 and at the end of bypass (T2). RESULTS: At T1, EXTEM differed from baseline for coagulation time: +26.7 s (18.4 to 34.9, P < 0.0001), α: -3° (1.0 to 5.4, P = 0.006) and A10: -4.4 mm (2.3 to 6.5, P = 0.0004). INTEM at T0 was different from HEPTEM at T1 for coagulation time: + 47 s (34.3 to 59.6, P >0.0001), A10: -2.3 mm (0.5 to 4.0, P = 0.01) and α -2° (1.0 to 3.0; P = 0.0007). At T2, all parameters in EXTEM and HEPTEM related to fibrin-platelet interaction deteriorated significantly compared to T1. At T3, EXTEM and INTEM were comparable to EXTEM and HEPTEM at T2. CONCLUSION: HEPTEM and EXTEM measurements are valid in the presence of very high heparin concentrations and can be performed before protamine administration in patients undergoing cardiac surgery with CPB. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01455454.

The impact of navigator timing parameters and navigator spatial resolution on 3D coronary magnetic resonance angiography.

The impact of navigator spatial resolution and navigator evaluation time on image quality in free-breathing navigator-gated 3D coronary magnetic resonance angiography (MRA), including real-time motion correction, was investigated in a moving phantom. Objective image quality parameters signal-to-noise ratio (SNR) and vessel sharpness were compared. It was found that for improved mage quality a short navigator evaluation time is of crucial importance. Navigator spatial resolution showed minimal influence on image quality.