Utilidad de la estación unipodal en la valoración del riesgo de caídas

Aimsto compare posturographic test with One-Leg Balance test in the elderly.Methodswe studied 59 healthy men and women living in the community who were at least 65 years of age. All of them were evaluated with One–Leg Balance (defined as the ability to stand on one leg unsupported for 5 seconds) and Modifies Clinical Test for the Sensory Interaction on Balance by the Balance Master (Neurocom®). We distributed the patients in two groups. Group A included those who couldn’t perform one-leg balance and group B those who could perform it.Results62.6% of subjects could perform one-leg balance and 37.2% could not perform it. On a firm surface with opened eyes, the A group made a variation of 0.4 deg/s (0.28-0.6) in the gravity center position and the B group 0,2 deg/s (0.1-0.3) (p = 0.010). On a firm surface with closed eyes, the A group made a variation of 0.5 deg/s (0.3-0.8) and the B group 0.3 deg/s (0.1- 0.4) (p = 0.002). On a foam surface with open eyes, the A group made a variation of their gravity center position of 1.10 deg/s (0.90-1.60) and the B group 0.9 deg/s (0.73-1.30) (p = 0.045). On a foam surface with closed eyes the A group made a variation of their gravity center position of 6 deg/s (4-6) and the B group 2.3 deg/s (1.63-3.08) (p < 0.001).Conclusionselderly patients who can perform one-leg balance, make less variations of their gravity centre. The results are the same when visual and propioceptive afferences are suppressed.     

The surface electromyographic evaluation of the Functional Reach in elderly subjects

This study proposes a comprehensive assessment of myoelectric activity of the main muscles involved in the Functional Reach (FR) test, in 24 elderly subjects. A specific protocol for the surface electromyography (sEMG) signal acquisition during FR-test was developed. Results show that anterior muscles activate following a caudo-cranial order. Tibialis Anterior (TA) is the first to be activated (−18.0 ± 16.3% of the FR-period), together with Rectus Femoris (−10.4 ± 17.9%). Then, Rectus Abdominis (19.7 ± 24.7%) and Sternocleidomastoideus (19.9 ± 15.6%) activate after the FR-start. Hamstrings, Soleus, and L4-level Erectores Spinae (posterior muscles) activate after the FR-start in this order (11.4 ± 16.8%, 17.7 ± 16.6%, and 35.2 ± 29.0%, respectively) and remain active until the movement end. The analysis of the kinematic strategies adopted by subjects revealed an association between TA-activation patterns and two kinematic strategies (hip/mixed strategy), quantified by an increase (p < 0.05) of TA-activity duration in subjects adopting the hip strategy (89.9 ± 34.5) vs. subjects adopting the mixed strategy (27.0 ± 16.8). This suggests that TA sEMG activity could be able to discriminate among kinematic strategies, providing different information on balance control. Thus, the present analysis represents the first attempt to quantify the sEMG activity during FR-test in elderly subjects, providing an early contribution in building a reference frame for balance assessment in clinical context.     

Testing prediction accuracy in short-term ecological studies

Applied ecology is based on an assumption that a management action will result in a predicted outcome. Testing the prediction accuracy of ecological models is the most powerful way of evaluating the knowledge implicit in this cause-effect relationship, however, the prevalence of predictive modeling and prediction testing are spreading slowly in ecology. The challenge of prediction testing is particularly acute for small-scale studies, because withholding data for prediction testing (e.g., via k-fold cross validation) can reduce model precision. However, by necessity small-scale studies are common. We use one such study that explored small mammal abundance along an elevational gradient to test prediction accuracy of models with varying degrees of information content. For each of three small mammal species, we conducted 5000 iterations of the following process: (1) randomly selected 75 % of the data to develop generalized linear models of species abundance that used detailed site measurements as covariates, (2) used an information theoretic approach to compare the top model with detailed covariates to habitat type-only and null models constructed with the same data, (3) tested those models’ ability to predict the 25 % of the randomly withheld data, and (4) evaluated prediction accuracy with a quadratic loss function. Detailed models fit the model-evaluation data best but had greater expected prediction error when predicting out-of-sample data relative to the habitat type models. Relationships between species and detailed site variables may be evident only within the framework of explicitly hierarchical analyses. We show that even with a small but relatively typical dataset (n = 28 sampling locations across 125 km over two years), researchers can effectively compare models with different information content and measure models’ predictive power, thus evaluating their own ecological understanding and defining the limits of their inferences. Identifying the appropriate scope of inference through prediction testing is ecologically valuable and is attainable even with small datasets.     

Quantification of triamcinolone acetonide in ocular tissues after intravitreal injection to rabbit using liquid chromatography-tandem mass spectrometry

A sensitive and selective liquid chromatographic-tandem mass spectrometric method was developed for quantification of triamcinolone acetonide (TA) in rabbit ocular tissues. After a simple liquid–liquid extraction using tert-butyl methyl ether, TA and internal standard methylprednisolone were separated on a C₁₈ column with a mobile phase of acetonitrile:water:formic acid (60:40:0.1, v/v/v) and quantified by the use of selected reaction monitoring mode with a total run time of 4 min. The method was validated in tissue homogenates with a daily working range of 1–1000 ng/mL with correlation coefficient of more than 0.99 and a sensitivity of 1 ng/mL as lower limit of quantification, respectively. The mean intra-day and inter-day precisions were less than 10% and accuracy values were higher than 90%. This method was fully validated for the accuracy, precision and stability studies. The method proved to be accurate and specific, and was applied to an in vivo biodistribution study of TA after intravitreal injection to rabbits. Values of mean residence time in vitreous humor, crystalline lens and aqueous humor were 27.7, 35.8 and 20.0 days, respectively.     

Influence of ankle functional instability on the ankle electromyography during landing after volleyball blocking

The purpose of this study was to describe, interpret and compare the EMG activation patterns of ankle muscles – tibialis anterior (TA), peroneus longus (PL) and gastrocnemius lateralis (GL) – in volleyball players with and without ankle functional instability (FI) during landing after the blocking movement. Twenty-one players with FI (IG) and 19 controls (CG) were studied. The cycle of movement analyzed was the time period between 200 ms before and 200 ms after the time of impact determined by ground reaction forces. The variables were analyzed for two different phases: pre-landing (200 ms before impact) and post-landing (200 ms after impact). The RMS values and the timing of onset activity were calculated for the three studied muscles, in both periods and for both groups. The co-activation index for TA and PL, TA and GL were also calculated. Individuals with FI presented a lower RMS value pre-landing for PL (CG = 43.0 ± 22.0; IG = 26.2 ± 8.4, p < 0.05) and higher RMS value post-landing (CG = 47.5 ± 13.3; IG = 55.8 ± 21.6, p < 0.10). Besides that, in control group PL and GL activated first and simultaneously, and TA presented a later activation, while in subjects with FI all the three muscles activated simultaneously. There were no significant differences between groups for co-activation index. Thus, the rate of contraction between agonist and antagonist muscles is similar for subjects with and without FI but the activation individually was different. Volleyball players with functional instability of the ankle showed altered patterns of the muscles that play an important role in the stabilization of the foot–ankle complex during the performance of the blocking movement, to the detriment of the ligament complex, and this fact could explain the usual complaints in these subjects.     

Muscle fiber conduction velocity in different gait phases of early and late-stage diabetic neuropathy

We investigated the muscle fiber conduction velocity (MFCV) during gait phases of the lower limb muscles in individuals with various degrees of diabetic peripheral neuropathy (DPN). Forty-five patients were classified into severity degrees of DPN by a fuzzy model. The stages were absent (n = 11), mild (n = 14), moderate (n = 11) and severe (n = 9), with 10 matched healthy controls. While walking, all subjects had their sEMG (4 linear electrode arrays) recorded for tibialis anterior (TA), gastrocnemius medialis (GM), vastus lateralis (VL) and biceps femoris (BF). MFCV was calculated using a maximum likelihood algorithm with 30 ms standard deviation Gaussian windows. In general, individuals in the earlier stages of DPN showed lower MFCV of TA, GM and BF, whilst individuals with severe DPN presented higher MFCV of the same muscles. We observed that mild patients already showed lower MFCV of TA at early stance and swing, and lower MFCV of BF at swing. All diabetic groups showed a markedly reduction in MFCV of VL, irrespective of DPN. Severe patients presented higher MFCV mainly in distal muscles, TA at early and swing phases and GM at propulsion and midstance. The absent group already showed MFCV of VL and GM reductions at the propulsion phase and of VL at early stance. Although MFCV changes were not as progressive as the DPN was, we clearly distinguished diabetic patients from controls, and severe patients from all others.     

An investigation of the simultaneously recorded occlusal contact and surface electromyographic activity of jaw-closing muscles for patients with temporomandibular disorders and a scissors-bite relationship

Surface electromyographic (SEMG) activity of the masseter and anterior temporalis (TA) muscles has been reported to be associated with occlusion and orofacial pain. However, our recent report did not reveal an association between the side of orofacial pain and the side showing higher or lower level of SEMG activity of masseter or TA. The present purpose was to re-test this association in patients who had unilateral scissors-bite relationship. Thirty-two unilateral scissors-bite femalepatients complaining of unilateral orofacial pain (n = 15) or TMJ sounds (n = 17) were enrolled to simultaneously record contacts, force distribution of occlusion, and SEMG activity of masseter and TA during centric maximal voluntary clenching (MVC). The results indicated that neither orofacial pain nor the TMJ sounds had an association with the masseter’s SEMG values, while scissors-bite had (P < 0.05). A lower SEMG value for masseter was found on the scissors-bite side where there was a smaller number of contacts and a lower biting force distribution (P < 0.05). No such association was revealed in TA. In conclusion, in patients with unilateral TMD symptom(s) and scissors-bite, the jawclosing muscles’ SEMG activity during centric MVC was associated with the scissors-bite rather than the symptoms of orofacial pain or TMJ sounds.     

Characterization of cervical lymph-nodes using a multi-parametric and multi-modal approach for an early prediction of tumor response to chemo-radiotherapy

PurposeIn the treatment of Head-and-Neck Squamous Cell Carcinoma (HNSCC), the early prediction of residual malignant lymph nodes (LNs) is currently required. Here, we investigated the potential of a multi-modal characterization (combination of CT, T2w-MRI and DW-MRI) at baseline and at mid-treatment, based on texture analysis (TA), for the early prediction of LNs response to chemo-radiotherapy (CRT).Methods30 patients with pathologically confirmed HNSCC treated with CRT were considered. All patients underwent a planning CT and two serial MR examinations (including T2w and DW images), one before and one at mid-CRT. For each patient the largest malignant LN was selected and within each LN, morphological and textural features were estimated from T2w-MRI and CT, besides a quantification of the apparent diffusion coefficient (ADC) from DW-MRI. After a median follow-up time of 26.6 months, 19 LNs showed regional control, while 11 LNs showed regional failure at a median time of 4.6 months. Linear discriminant analysis was used to test the accuracy of the image-based features in predicting the final response.ResultsPre-treatment features showed higher predictive power than mid-CRT features, the ADC having the highest accuracy (80%); CT-based indices were found not predictive. When ADC was combined with TA, the classification performance increased (accuracy = 82.8%). If only T2w-MRI features were considered, the best combination of pre-CRT indices and their variation reached an equivalent accuracy (81.8%).ConclusionOur results may suggest that TA on T2w-MRI and ADC can be combined together to obtain a more accurate prediction of response to CRT.     

Efectos del estado cognitivo sobre las alteraciones del equilibrio y la marcha en ancianos institucionalizados

BackgroundAgeing has been linked to a high prevalence of cognitive impairment, which, in turn, has been related to balance disturbances and gait disorders. The aim of this study was to identify whether there are differences between subjects with and without cognitive impairment regarding the quality of gait and balance.Material and methodsAn observational study was conducted on institutionalised people older than 65 years (n = 82). Gait and balance was evaluated after the assessment of cognitive impairment using the Mini-Mental State Examination (MMSE). Single and dual tests were used including, the 6-minute walking, stride length, and gait speed. Timed Up and Go tests were also used to evaluate balance.ResultsThe participants were divided into three groups: 28 subjects in the group without cognitive impairment (MMSE ≥ 27), 29 subjects with mild (27 < MMSE ≤ 21) and 26 subjects with moderate cognitive impairment (MMSE < 21). Gait assessment showed significant between-groups differences in all the variables (P < .05). The variables assessing balance also showed significantly worse values in those groups with cognitive impairment.ConclusionThe severity of cognitive impairment is related to impaired balance and gait, thus the clinical monitoring of these variables in population at risk is needed.     

Mechanisms that influence accuracy of the soccer kick

Goal scoring represents the ultimate purpose of soccer and this is achieved when players perform accurate kicks. The purpose of the present study was to compare accurate and inaccurate soccer kicks aiming to top and bottom targets. Twenty-one soccer players performed consecutive kicks against top and bottom targets (0.5 m²) placed in the center of the goal. The kicking trials were categorized as accurate or inaccurate. The activation of tibialis anterior (TA), rectus femoris (RF), biceps femoris (BF) and gastrocnemius muscle (GAS) of the swinging leg and the ground reaction forces (GRFs) of the support leg were analyzed. The GRFs did not differ between kicking conditions (P > 0.05). There was significantly higher TA and BF and lower GAS EMG activity during accurate kicks to the top target (P < 0.05) compared with inaccurate kicks. Furthermore, there was a significantly lower TA and RF activation during accurate kicks against the bottom target (P < 0.05) compared with inaccurate kicks. Enhancing muscle activation of the TA and BF and reducing GAS activation may assist players to kick accurately against top targets. In contrast, players who display higher TA and RF activation may be less accurate against a bottom target. It was concluded that muscle activation of the kicking leg represents a significant mechanism which largely contributes to soccer kick accuracy.     

How to efficiently obtain accurate estimates of flower visitation rates by pollinators

Regional declines in insect pollinators have raised concerns about crop pollination. Many pollinator studies use visitation rate (pollinators/time) as a proxy for the quality of crop pollination. Visitation rate estimates are based on observation durations that vary significantly between studies. How observation duration relates to the accuracy of the visitation rate estimate is, however, unknown. We studied this relationship using six day-long observations (06:00 h–19:00 h) in leek-seed production fields (totalling 78 h). We analysed beyond which point in time observing longer did not significantly improve the accuracy of the visitation rate estimate (minimum observation duration). We furthermore explored the relationship between the minimum observation duration and visitation rate, time of day and temperature. We found that the minimum observation duration (mean ± SD: 24 ± 11.9 min) was significantly related to visitation rate, where the observation time required to obtain accurate estimates decreased with increasing visitation rate. Minimum observation duration varied greatly between days and between fields but not within days. Within days, the visitation rates differed significantly only between the hour-intervals 06:00 h–07:00 h (lowest visitation rate) and 09:00 h–11:00 h (highest rate). Minimum observation duration decreased up to around 22 °C beyond which it remained fairly stable. Surprisingly, even after three day-long observations on the same plant we found new pollinator species visiting the flowers, suggesting that species-richness estimates based on plant observations alone probably underestimate true species richness. Because especially between-day variation in visitation rate on single plants can be large, reliable estimates of the pollinator visitation rate during the plant’s flowering time require observations on multiple days. Standardising the number of pollinators rather than the time to observe (standardised pollinator timing approach: time to n-pollinator visits) may provide more consistent accurate assessments of visitation rate, especially for studies that use gradients in visitation rates to examine the contribution of pollinators to crop pollination.     

Small molecule tolfenamic acid and dietary spice curcumin treatment enhances antiproliferative effect in pancreatic cancer cells via suppressing Sp1, disrupting NF-kB translocation to nucleus and cell cycle phase distribution

Combination of dietary/herbal spice curcumin (Cur) and COX inhibitors has been tested for improving therapeutic efficacy in pancreatic cancer (PC). The objective of this study was to identify agent with low toxicity and COX-independent mechanism to induce PC cell growth inhibition when used along with Cur. Anticancer NSAID, tolfenamic acid (TA) and Cur combination were evaluated using PC cell lines. L3.6pl and MIA PaCa-2 cells were treated with Cur (5–25 μM) or TA (25–100 μM) or combination of Cur (7.5 μM) and TA (50 μM). Cell viability was measured at 24–72 h posttreatment using CellTiter-Glo kit. While both agents showed a steady/consistent effect, Cur + TA caused higher growth inhibition. Antiproliferative effect was compared with COX inhibitors, Ibuprofen and Celebrex. Cardiotoxicity was assessed using cordiomyocytes (H9C2). The expression of Sp proteins, survivin and apoptotic markers (western blot), caspase 3/7 (caspase-Glo kit), Annexin-V staining (flow cytometry), reactive oxygen species (ROS) and cell cycle phase distribution (flow cytometry) was measured. Cells were treated with TNF-α, and NF-kB translocation from cytoplasm to nucleus was evaluated (immunofluorescence). When compared to individual agents, combination of Cur + TA caused significant increase in apoptotic markers, ROS levels and inhibited NF-kB translocation to nucleus. TA caused cell cycle arrest in G₀/G₁, and the combination treatment showed mostly DNA synthesis phase arrest. These results suggest that combination of Cur + TA is less toxic and effectively enhance the therapeutic efficacy in PC cells via COX-independent mechanisms.     

Extra-torque of human tibialis anterior during electrical stimulation with linearly varying frequency and amplitude trains

This work aimed to characterise the whole human muscle input/output law during electrical stimulation with triangular varying frequency and amplitude trains through combined analysis of torque, mechanomyogram (MMG) and electromyogram (EMG).The tibialis anterior (TA) of ten subjects (age 23–35 years) was investigated during static contraction obtained through neuromuscular electrical stimulation. After potentiation, TA underwent two 15 s stimulation patterns: (a) frequency triangle (FT): 2 > 35 > 2 Hz at Vmax (amplitude providing full motor unit recruitment); (b) amplitude triangle (AT): Vmin > Vmax > Vmin (Vmin providing TA least mechanical response) at 35 Hz. 2 > 35 Hz or Vmin > Vmax as well as 35 > 2 Hz or Vmax > Vmin were defined as up-going ramp (UGR) and down-going ramp (DGR), respectively. TA torque, MMG and EMG were detected by a load cell, an optical laser distance sensor and a probe with two silver bar electrodes, respectively. For both FT and AT, only the two mechanical signals resulted always larger in DGR than in UGR, during AT extra-torque and extra-MMG were present even in the first 1/3 of the amplitude range where EMG data presented no significant differences between DGR and UGR.Our data suggest that extra-torque and extra-displacement are evident for both FT and AT, being mainly attributed to an intrinsic muscle property.     

Ultrasonographic assessment of early pregnancy diagnosis,fetometry and sex determination in goats

This study was conducted to use B-mode trans-rectal (TR) and trans-abdominal (TA) ultrasonography to determine early pregnancy and fetometry as crown-rump-length (CRL) and bi-parietal-diameter (BPD). A total of 110 does aged between 8 and 36 months were used. The accuracy for detecting early pregnancy (fetal fluids and heartbeats) and fetal number (single or twins) was measured. The relationship between gestation age and CRL or BPD was determined from day 40 to 109 of gestation. The accuracy of fetal sexing was determined by differentiation of genital tubercle (GT) at different stages of gestation (from day 40 to 109 of gestation). The examination revealed 95.5% of examined does were pregnant, with accuracy 100% in detecting pregnancy for positive cases. The fetal number was 45.7% and 54.3% for single and twins + triplets, respectively. The TR probe enabled the reliable and earlier recognition of fetal fluid and heartbeats (indicating pregnancy) than TA probe. For maximum reliability, the TR observation of heartbeats is recommended as conclusive evidence of the presence of a live fetus. The TA convex probe was used from day 40 to 89 for measuring CRL and from day 40 to 109 for measuring the BPD. Gestation equations were: CRL = 0.464x ? 17.767 and BPD = 0.055x ? 1.431 (x = gestational age in days). The relation between gestational age and CRL or BPD was highly (p < 0.0001) significant. The fetal sexing was found in 100, 83.3 and 64.3% of single pregnancies and in 85.7, 80 and 52.3% of twins + triplets pregnancies during 40–60 days, 61–70 days and 71–109 days of gestation, respectively. The accuracy of sex identification among the 3 groups was not significantly (p > 0.05) higher in single than twins + triplets pregnancies. However, identification of GT in male fetus was possible from day 40 onward. From a total of 105 scanned does, 80 (76.25) were sexed. In conclusion, B-mode real-time ultrasonography is recommended as a reliable mean for early detection of gestation as early as 19–27 days after mating, for CRL or BPD measuring as well as fetal sex determination from day 40 of gestation onwards under field conditions.     

Modeling balance control during sustained waking allows posturographic sleepiness testing

We develop a method to quantify sleepiness. Sleepiness is a major risk factor in traffic and occupational accidents, but lack of convenient tests precludes monitoring impending sleepiness. Posturographic balance testing could address this need because sleepiness increases postural sway. It is, however, unclear how sleepiness influences balance control. Our results, for 12 subjects, show that balance control is more susceptible to increasing time awake (TA) compared to neuromuscular processes. This conclusion is reached since during sustained waking the control process slows down by 3.4% per hour of increased TA. This slowdown accounts for 65% of the variance in diurnal balance. We quantified balance control by modeling the body as an inverted pendulum and by expressing the control as the critical time interval for open-loop control (Deltat(c)) of the center-of-mass movements of this pendulum. To estimate the subjects' TA, we regressed the Deltat(c) scores recorded during sustained waking against increasing TA, and equated separate Deltat(c) test scores with the diurnal Deltat(c) scores. We estimated TA with 68% positive predictive value. The results encourage implementing balance modeling into a device that performs clinical or industrial balance testing because the model-based Deltat(c) score responded to increasing TA.     

Improved method for the determination of cyclic guanosine monophosphate (cGMP) in human plasma by LC–MS/MS

Cyclic guanosine monophosphate (cGMP) is an important second messenger molecule involved in gating ion channels and activating protein kinases. Here, we describe a validated LC–MS/MS method for the quantification of cGMP in human plasma, utilizing a stable isotope labeled analogue of cGMP as I.S. Plasma samples were extracted and concentrated by weak anion exchange solid phase extraction and the extracts were chromatographically separated on a porous graphitic carbon column. The analytes were detected by positive electrospray ionization and tandem mass spectrometry. The calibration function was linear in the range 1–20 nM and the intra- and inter-day precision showed relative standard deviations of better than 2 and 6%, respectively. The accuracy was always better than 4%. Plasma concentrations in healthy human subjects determined with this method were 3.92 ± 1.17 nM (n = 20). The method was, due to its isotope labeled I.S., matrix independent.     

Prostate-specific antigen screening of workers under the age of 40 in Japan

Background: There is no agreement on the usefulness of the prostate-specific antigen (PSA) test for prostate cancer screening in young men in Japan. We believe that medical check-up departments in hospitals conduct prostate cancer screening in subjects under 40 years of age undergoing intensive health check-up for commercial reasons, and speculate that some medical doctors provide tacit consent for this action. To understand the prevalence of PSA testing in young men, the authors examined the age distribution of workers who underwent the PSA test. Methods: The authors used the 2009 intensive health check-up data of male workers aged 30–65 years (n = 298) in a car-manufacturing company to investigate the status of prostate-cancer screening in young men. Multiple comparison was conducted by Tukey's method when the analysis of variance revealed significant difference. Results: According to the frequency distribution of age, 15.8% of the subjects were under 40 years of age. The mean PSA value increased with age, ranging from 1.0 ng/mL in subjects in their 30s’, to 2.0 ng/mL in subjects in their 60s’. The mean PSA level in subjects in their 60s’ was significantly higher than that in subjects in their 30s’ and 40s’. The percentage of subjects with serum PSA levels of 4 ng/mL or higher in subjects in their 30s’, 40s’, 50s’ and 60s’ were 2.1% (1/47), 1.6% (2/125), 4.4% (5/114) and 8.3% (1/12), respectively. Conclusions: One-sixth of male workers attending the health check-up program were under 40 years of age. According to the criteria of the Japanese Urological Association, this examination program included younger subjects who were not candidates for PSA screening.     

Differences in proprioception,muscle force control and comfort between conventional and new-generation knee and ankle orthoses

The aim of this study was to compare muscle force control and proprioception between conventional and new-generation experimental orthoses. Sixteen healthy subjects participated in a single-blind controlled trial in which two different types of orthosis were applied to the dominant knee or ankle, while the following variables were evaluated: muscle force control (accuracy), joint position sense, kinesthesia, static balance as well as subjective outcomes. The use of experimental orthoses resulted in better force accuracy during isometric knee extensions compared to conventional orthoses (P = 0.005). Moreover, the use of experimental orthoses resulted in better force accuracy during concentric (P = 0.010) and eccentric (P = 0.014) ankle plantar flexions and better knee joint kinesthesia in the flexed position (P = 0.004) compared to conventional orthoses. Subjective comfort (P < 0.001) and preference scores were higher with experimental orthoses compared to conventional ones. In conclusion, orthosis type affected static and dynamic muscle force control, kinesthesia, and perceived comfort in healthy subjects. New-generation experimental knee and ankle orthoses may thus be recommended for prophylactic joint bracing during physical activity and to improve the compliance for orthosis use, particularly in patients who require long-term bracing.     

Assessing the accuracy and precision of musculoskeletal motion tracking using cine-PC MRI on a 3.0T platform

The rising cost of musculoskeletal pathology, disease, and injury creates a pressing need for accurate and reliable methods to quantify 3D musculoskeletal motion, fostering a renewed interest in this area over the past few years. To date, cine-phase contrast (PC) MRI remains the only technique capable of non-invasively tracking in vivo 3D musculoskeletal motion during volitional activity, but current scan times are long on the 1.5T MR platform (～2.5 min or 75 movement cycles). With the clinical availability of higher field strength magnets (3.0T) that have increased signal-to-noise ratios, it is likely that scan times can be reduced while improving accuracy. Therefore, the purpose of this study is to validate cine-PC MRI on a 3.0T platform, in terms of accuracy, precision, and subject-repeatability, and to determine if scan time could be minimized. On the 3.0T platform it is possible to limit scan time to 2 min, with sub-millimeter accuracy (<0.33 mm/0.97°), excellent technique precision (<0.18°), and strong subject-repeatability (<0.73 mm/1.10°). This represents reduction in imaging time by 25% (42 s), a 50% improvement in accuracy, and a 72% improvement in technique precision over the original 1.5T platform. Scan time can be reduced to 1 min (30 movement cycles), but the improvements in accuracy are not as large.     

Validation of cell density and viability assays using Cedex automated cell counter

A method using Cedex automatic cell counter (Innovatis) to determine the cell density and viability of a whole cell-based immunotherapy product has been developed and validated for the assay performance characteristics including specificity, accuracy, precision, linearity, range, and robustness. Instrument-to-instrument variation due to intrinsic differences in handmade flow cells was also evaluated. For cell density, Cedex demonstrated acceptable specificity, accuracy and precision for cell densities ranging from 3.13 × 10⁵ to approximately 1.0 × 10⁷ cells/mL, with intermediate precision of about 5% relative standard deviation (RSD). However, a marked difference was observed between the two instruments studied and they therefore could not be used interchangeably without additional calibration procedures that went beyond the manufacturer's recommendation. For viability, mixing known numbers of non-viable cells with highly viable cells allowed evaluation of the specificity, accuracy and linearity of the viability determination. Acceptable levels of accuracy (95.3–106.4% recovery) and precision (RSD < 5%) were demonstrated for the viability range from 50 to 100%. The instrument-to-instrument difference was less than 4.6%. The assays for both cell density and viability were sufficiently robust for assay parameters. However, the effect of certain parameters was cell line-dependent, suggesting that Cedex performance should be verified for each cell line of interest.