The forced vital capacity (FVC) maneuver is the most common lung function test. One of its major prerequisites is that it be performed with sufficient effort to achieve the maximal flows that are due to expiratory flow limitation. To verify this, in nine normal subjects, short (0.25-s) pulses of negative pressure (-5 to -20 cmH2O) were applied at the mouth at different times (0.25-1 s) after the onset of 1) FVC maneuvers and 2) vital capacity expirations with submaximal expiratory efforts (SVC). All subjects were experienced in FVC maneuvers. With FVC, the expiratory flow did not change with application and removal of negative-pressure pulses, apart from brief flow transients, mainly reflecting displacement of air from the compliant oral and neck structures. With SVC, flow increased throughout the application of the negative-pressure pulses. Thus application of pulses of negative pressure provides a simple method for on-line recognition of whether an FVC maneuver is performed with sufficient effort to achieve flow limitation.

• MeSH
• cvičení fyziologie   MeSH
• dospělí MeSH
• lidé MeSH
• respirační funkční testy * metody   MeSH
• usilovný výdechový objem MeSH
• ventilátory s negativním tlakem MeSH
• vitální kapacita * MeSH
• vrcholová exspirační průtoková rychlost MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• klinické zkoušky MeSH
• práce podpořená grantem MeSH

The present study evaluates the compression process of tablets containing microcrystalline cellulose, lactose or calcium hydrogenphosphate dihydrate. The evaluation used the force-displacement record and stress relaxation test. The obtained results also showed that both othe methods based on different principles are comparable.

• MeSH
• celulosa MeSH
• farmaceutická technologie * MeSH
• farmaceutické pomocné látky MeSH
• fosforečnany vápenaté MeSH
• fyzikální jevy MeSH
• laktosa MeSH
• lékové formy MeSH
• mechanické jevy MeSH
• metody MeSH
• pevnost v tahu MeSH
• pevnost v tlaku MeSH
• příprava léků * MeSH
• tablety MeSH

A new method to estimate the selected viscoelastic parameters of foods using damped vibration analysis is presented for the evaluation of fruits and baked products. A flat disk is attached to the flat sample surface using a laser rangefinder that measures the sample thickness in advance, and it is locked by a trigger. Next, the trigger is released to allow the probe to press the sample through the force of gravity. The damped vibration of the probe caused by the deformation of the food is measured by monitoring the displacement of the probe via a linear encoder. The bulk modulus and viscosity are estimated using the fractional Zener model and mass. Young's modulus (E) is estimated independently by determining the maximum velocity of the probe using Hooke's law. Poisson's ratio (ν), and the shear modulus and viscosity are calculated by employing the estimated E and bulk modulus. The bulk modulus, bulk viscosity, shear modulus, shear viscosity, and E of apples were found to be higher than those of bananas. The bulk modulus, bulk viscosity, E, and shear modulus for white bread were lower than those for pound cake, but the ν values were higher, whereas those of sponge cake were intermediate. After drying the baked products for 1 day, most of the parameters of the samples increased, but the value of ν for white bread decreased. The proposed free-falling device estimated the four viscoelastic coefficients, Poisson's ratio, and Young's modulus of the food sample in less than 1 s.

• MeSH
• modul pružnosti MeSH
• pružnost * MeSH
• viskozita MeSH
• Publikační typ
• časopisecké články MeSH

PURPOSE OF THE STUDY The presented study was construed as a retrospective multicentric clinical study focused on paediatric skeletal injuries of the proximal radius. As a general rule, the Type I displaced fractures (Judet classification) are treated conservatively, with no reduction. In the case of Type II-IV displacement, the fracture necessitates reduction or is also transfixed by a Kirschner wire (K-wire) or a Prevot nail (P-nail) where subsequent fragment instability occurs. The comparison aimed to ascertain whether there is a statistically significant difference between the two methods. No difference was expected by the authors, therefore a null hypothesis was set. MATERIAL AND METHODS The patients were treated at the Clinic of Paediatric Surgery, Orthopaedics and Traumatology (CPSOT) of the Faculty of Medicine of the Masaryk University and at the Clinic of Orthopaedics and Traumatology of the Musculoskeletal System of the University Hospital in Pilsen in the period from 2006 to 2015. Two methods of closed reduction and minimally- invasive osteosynthesis were evaluated. The first method was the elastic stable intramedullary nailing (ESIN) with a P-nail, the second method was an osteosynthesis using a K-wire. In the clinical part of the study, comparisons were made based on the monitoring of the same parameters - final restriction of movement, time to full weight bearing of the extremity and incidence of serious complications. RESULTS The final group comprised a total of 31 patients, of whom 7 boys and 24 girls aged 3-16 years with the median of 9-10 years. Some restriction of movement following the treatment occurred in a total of seven patients (44%) with the K-wire and in four patients (27%) with the P-nail. When comparing the movement at 5% level of significance using the Chi-Square tests, no significant difference was found (p = 0.446). When evaluating the serious complications at 5% level of significance using the Chi-Square tests, the difference between the two methods of treatment was again insignificant (p = 0.365). When the full weight bearing was compared (median K-wire 8 weeks, median P-nail 10 weeks), a statistically significant difference was obtained at 5% level of significance using the Fischer exact test (p = 0.003). DISCUSSION In these fractures, usually the metaphysis or the physis are involved in the injury, in which case the fractures are classified according to Salter and Harris, with the most frequent occurrence of SHII epiphyseal separation and rare SHIII and SHIV epiphyseal fractures. The radial head fractures are mostly caused by valgus force. Therefore, the individuals with a higher elbow valgosity are more prone to injuries. The girls strongly prevail (77%) also in our study. In general, our results as well as the literature have proven that as the displacement increases, the necessity of closed reduction and osteosynthesis grows. The post-treatment complications in our group were observed in 35.5% of patients, namely most often in the form of limited movement. The literature refers to complications in 26.5-53% of patients. CONCLUSIONS The clinical results clearly show that when comparing the complications after the radial head fracture in children there is no statistically significant difference between the methods of osteosynthesis. This study shall serve as a starting point for the currently ongoing prospective multicentric study evaluating the modified ESIN technique using a pre-bent Kirschner wire. Key words:children, fracture, radius, proximal, osteosynthesis.

• MeSH
• dítě MeSH
• fraktury vřetenní kosti * diagnóza   chirurgie   MeSH
• intramedulární fixace fraktury * škodlivé účinky   přístrojové vybavení   metody   MeSH
• konzervativní terapie * škodlivé účinky   metody   MeSH
• kostní dráty MeSH
• kostní hřeby * MeSH
• lidé MeSH
• miniinvazivní chirurgické výkony metody   MeSH
• mladiství MeSH
• pooperační komplikace * diagnóza   etiologie   MeSH
• předškolní dítě MeSH
• radius * diagnostické zobrazování   zranění   chirurgie   MeSH
• rozsah kloubních pohybů MeSH
• výsledek terapie MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• klinické zkoušky MeSH
• multicentrická studie MeSH

INTRODUCTION: This systematic review aims to identify previously used techniques in biomechanics to assess pelvic instability following pelvic injury, focusing on external fixation constructs. METHODS: A systematic literature search was conducted to include biomechanical studies and to exclude clinical trials. RESULTS: Of an initial 4666 studies found, 38 met the inclusion criteria. 84% of the included studies were retrieved from PubMed, Scopus, and Web of Science. The studies analysed 106 postmortem specimens, 154 synthetic bones, and 103 computational models. Most specimens were male (97% synthetic, 70% postmortem specimens). Both the type of injury and the classification system employed varied across studies. About 82% of the injuries assessed were of type C. Two different fixators were tested for FFPII and type A injury, five for type B injury, and fifteen for type C injury. Large variability was observed for external fixation constructs concerning device type and configuration, pin size, and geometry. Biomechanical studies deployed various methods to assess injury displacement, deformation, stiffness, and motion. Thereby, loading protocols differed and inconsistent definitions of failure were determined. Measurement techniques applied in biomechanical test setups included strain gauges, force transducers, and motion tracking techniques. DISCUSSION AND CONCLUSION: An ideal fixation method should be safe, stable, non-obstructive, and have low complication rates. Although biomechanical testing should ensure that the load applied during testing is representative of a physiological load, a high degree of variability was found in the current literature in both the loading and measurement equipment. The lack of a standardised test design for fixation constructs in pelvic injuries across the studies challenges comparisons between them. When interpreting the results of biomechanical studies, it seems crucial to consider the limitations in cross-study comparability, with implications on their applicability to the clinical setting.

• MeSH
• biomechanika MeSH
• externí fixátory MeSH
• fixace fraktury metody   MeSH
• fraktury kostí * MeSH
• lidé MeSH
• pánevní kosti * chirurgie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• systematický přehled MeSH

Atomic force microscopy (AFM) is not only a high-resolution imaging technique but also a sensitive tool able to study biomechanical properties of bio-samples (biomolecules, cells) in native conditions-i.e., in buffered solutions (culturing media) and stable temperature (mostly 37 °C). Micromechanical transducers (cantilevers) are often used to map surface stiffness distribution, adhesion forces, and viscoelastic parameters of living cells; however, they can also be used to monitor time course of cardiomyocytes contraction dynamics (e.g. beating rate, relaxation time), together with other biomechanical properties. Here we describe the construction of an AFM-based biosensor setup designed to study the biomechanical properties of cardiomyocyte clusters, through the use of standard uncoated silicon nitride cantilevers. Force-time curves (mechanocardiograms, MCG) are recorded continuously in real time and in the presence of cardiomyocyte-contraction affecting drugs (e.g., isoproterenol, metoprolol) in the medium, under physiological conditions. The average value of contraction force and the beat rate, as basic biomechanical parameters, represent pharmacological indicators of different phenotype features. Robustness, low computational requirements, and optimal spatial sensitivity (detection limit 200 pN, respectively 20 nm displacement) are the main advantages of the presented method.

• MeSH
• biomechanika * MeSH
• biosenzitivní techniky MeSH
• kardiomyocyty cytologie   MeSH
• lidé MeSH
• mikroskopie atomárních sil * přístrojové vybavení   metody   MeSH
• pluripotentní kmenové buňky cytologie   MeSH
• preklinické hodnocení léčiv MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

OBJECTIVE: Postural control is a complex skill based on the interaction of dynamic sensorimotor processes. This study assessed the effect of lateral perturbations on postural re-stabilization regarding lower limb preference. METHODS: A group of 14 physically active individuals (9 male, 5 female) randomly underwent postural perturbations in lateral-left and lateral-right directions at a velocity of 0.2 m.s-1 and a platform shift of 6 cm. Perturbation to the preferred limb side (PS) was noted when the contralateral body movement was primarily controlled by the preferred limb and perturbation to the non-preferred limb side (NS) was noted when the contralateral body movement was primarily controlled by the non-preferred (stabilizing) limb. Prior to, during and after the perturbation centre of pressure (CoP) was registered using a computerized motor driven FiTRO Dynamic Posturography System based on force plate (Fitro Sway Check) with a sampling rate of 100 Hz. The basic stabilographic parameters of peak displacement (Peak 1), peak-to-peak displacement (Peak 2), time to peak displacement (Time 1), time to peak-to-peak displacement (Time 2) and re-stabilization time (Time 3) were analyzed. RESULTS: Results showed significantly larger Time 3 on PS than on NS (2.81 ± 1.32 s and 1.73 ± 1.10 s; p=0.02). However, there were no significant differences in other parameters between PS and NS. CONCLUSION: It may be concluded that the observed shorter re-stabilization time at NS was due to the stabilization role of the non-preferred limb.

• MeSH
• dolní končetina fyziologie   MeSH
• dospělí MeSH
• funkční lateralita fyziologie   MeSH
• lidé MeSH
• mladý dospělý MeSH
• postura těla fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This book deals with the mechanics of impacts and vibrations and mitigation of their effects. It brings the expressions for impacts and for velocity, displacement and force in various cases of braking or stopping, and pays attention to the fact that force impulses propagate in bodies only with limited velocity. Then, it shows how various materials respond to load, how they absorb energy and how they can fail. Further it describes technical means for impact energy absorption, such as bend parts, compressed shells, composites, air cushions and hydraulic shock dampers with constant deceleration. One chapter is devoted to vibrations and mitigation of their effects. Formulae are presented for free and forced vibrations, without or with damping, and attention is also paid to the transmission of forces into foundations and to kinematic exciting, appearing during a vehicle ́s ride on a wavy road. Also a dynamic absorber of vibrations is described and vibrations of a system of several bodies. More complex analysis needs numerical methods, such as the finite element method. The last chapter is devoted to the dimensional analysis and theory of similarity, which can spare work during the development of appliances for the damping of impacts and vibrations. The book contains explanatory examples, numerous figures and references.

PURPOSE OF THE STUDY The study gives a retrospective assessment of the outcomes of surgical treatment in patients who sustained a subtrochanteric fracture. MATERIAL AND METHODS In the period 2010-2018, a total of 118 patients with a subtrochanteric fracture, namely 75 males and 43 females, the mean age 61 years, were treated at our department. The study group included the patients who met the following inclusion criteria: age 18+, fracture treated by intramedullary nailing, follow-up for at least 12 months, in case of impaired healing and need for revision surgery follow-up until complete healing was achieved. Exclusion criteria - pathological fractures, periprosthetic fractures, pertrochanteric fractures with extension into subtrochanteric region, intertrochanteric fractures, fractures during bisphosphonate treatment, incomplete radiological documentation, non-compliance with the condition of 12-month follow-up. In 54 patients (46%) the injury was caused by high-energy impact, in the remaining 64 patients (54%) the fracture was the consequence of low energy mechanism. In 51 patients (43%) closed reduction was performed and 67 patients (57%) underwent open reduction. In 27 patients (23%) a small incision laterally was necessary to insert the reduction instrument in order to achieve correct position of the fracture. In 40 patients (34%) lateral approach was used for the reduction and proper placement of fragments was ensured by one or more cerclage wires prior to nailing. Nails made by Synthes were used for osteosynthesis: PFN A Long in 95 patients, PFN A in 11 patients and LFN in 12 patients. RESULTS In 76 patients (64%) fractures healed within 6 months, in 107 patients (90%) within 9 months. In 11 patients (10%) nonunion was observed that required another surgery. The outcomes were assessed using the Sanders and Regazzoni scoring system. Excellent outcome was achieved in 79 cases (67%), good outcome in 25 cases (21%), satisfactory outcome in 13 cases (11%), poor outcome in 1 case (1%). DISCUSSION At any age subtrochanteric fractures are always treated surgically. Currently, intramedullary nailing is the method of choice. The outcome of the surgery depends on correct reduction and fixation which shall ensure the balance of compression forces transmitted to the medial cortical bone, traction forces transmitted to the lateral femoral cortical bone. Intramedullary nailing has biomechanical advantages which outweigh the often difficult closed reduction. The nail decreases the position vector (of the force moment) and reduces torsional forces at the fracture site. Open reduction and additional cerclage wires are described as a risk factor for impaired healing. Nevertheless, the achievement of anatomical reduction offsets the risk of poor blood supply at the fracture site. Persistent displacement disturbs the balance of forces and results in impaired healing and implant failure. CONCLUSIONS Treatment of subtrochanteric fractures relies on precise reduction. Today, when minimally invasive methods of treatment are preferred, the most commonly used are the intramedullary implants. Displacement to varosity, flexion displacement or a combination of both cause impaired healing with non-union and failed osteosynthesis. Treatment of non-union is extremely challenging and always consists in the correction of anatomical relationships. Key words: subtrochanteric fractures, surgical treatment, outcomes, complications.

• MeSH
• fraktury kyčle * diagnostické zobrazování   chirurgie   MeSH
• hojení fraktur MeSH
• intramedulární fixace fraktury * škodlivé účinky   MeSH
• kostní dráty MeSH
• kostní hřeby MeSH
• lidé středního věku MeSH
• lidé MeSH
• retrospektivní studie MeSH
• vnitřní fixace fraktury MeSH
• výsledek terapie MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Good flow and compaction properties are necessary for the manipulation of particulate material in the pharmaceutical industry. The influence of the addition of an alternative sweetener, rebaudioside A, in a concentration 0.2% w/w and 0.5% w/w on the flow, shear and compaction properties of sorbitol for direct compaction, Merisorb® 200, was investigated in this work. Rebaudioside A worsened the flow properties of sorbitol: the Hausner ratio, the compressibility index and the mass flow rate through the aperture of a model hopper. Using a Jenike shear cell revealed a significant increase in cohesion leading to the decrease of the flow function; moreover, the addition of rebaudioside A increased the total energy for compression of tablets and plasticity estimated by the force-displacement method. Finally, the tablets showed a higher tensile strength and needed longer time to disintegrate compared to the tablets made of sorbitol itself. In view of the results for the free-flowable excipient, sorbitol, the effects of stevia even for a 0.2% w/w concentration have to be carefully considered, particularly whenever used in pharmaceutical formulations of poor flow properties.

• MeSH
• diterpeny kauranové chemie   MeSH
• farmaceutická technologie metody   MeSH
• pevnost v tahu MeSH
• pomocné látky chemie   MeSH
• příprava léků metody   MeSH
• sladidla chemie   MeSH
• sorbitol chemie   MeSH
• Stevia chemie   MeSH
• tablety chemie   MeSH
• tlak MeSH
• Publikační typ
• časopisecké články MeSH