The role of strength in rising from a chair in the functionally impaired elderly

Rising from a chair is a task essential for independent living. Many elderly persons have difficulty with this task. Previous studies have drawn conflicting conclusions as to the role of strength in limiting the ability to rise from a chair. The purpose of this study is to determine the role of knee extensor strength in rising from a chair in the functionally impaired elderly. It is hypothesized that knee extensor strength limits the minimum chair height from which a subject can rise in the functionally impaired elderly, but not in the young. Studying both young healthy adults and functionally impaired elderly showed that required joint moment increased monotonically with decreasing chair height. Further, the elderly used significantly more of their available strength to rise from any chair height, and their mean required knee moment was 97% of the available strength when rising from the lowest chair height from which they could successfully rise. These data suggest that strength is a limiting factor in determining the minimum chair height from which the functionally impaired elderly may rise     

Body segments decoupling in sitting: control of body posture from automatic chair adjustments

Background

Individuals who cannot functionally reposition themselves adopt a passive body posture and suffer from physical discomfort in long-term sitting. To regulate body load and to prevent sitting related mobility problems, proper posture control is important. The inability to reposition underlines the importance for seating interventions that control body posture from automatic chair adjustments. We developed an adjustable simulator chair that allows the alignment of the trunk, pelvis and thighs to be controlled independently. This study describes the system for decoupled body segments adjustment and develops a predictive model that computes angular chair configuration for desired body postures.

Methods

Eighteen healthy male subjects participated in this study. The experiment involved a protocol of five trials, each investigating the effect of individual chair segment angle adjustment on body segments rotation. Quasi-static chair adjustments were performed, in which angular chair configuration and body segments orientation were measured using an infrared motion capturing system and an inertia sensor attached on the pelvis.

Results

Linear best-fit equations together with the coefficients of determination were computed. Significant relations have been found between angular chair configuration and body segments orientation leading to an algorithm that predicts chair configuration for desired body posture.

Conclusions

The predictive algorithm seems applicable to compute angular chair configuration for desired body posture when the initial body–chair configuration is known. For clinical application, future experiments must be performed on impaired individuals to validate the algorithm in terms of accuracy.     

Development of an inexpensive, low attenuation styrofoam primate chair for use in a PET scanner

Pharmacokinetic modelling of radiotracers for positron emission tomography (PET) imaging of neuroreceptors can be performed with time-activity data for brain and blood. We aimed to develop an alternative to withdrawal of arterial blood samples for acquisition of a blood curve. A supportive primate chair was constructed out of styrofoam and fixed to the head portion of the bed of a PET scanner. A lightly anaesthetised rhesus monkey was positioned in the chair in a sitting position and injected with the radiotracer. The styrofoam chair provided sufficient support for the monkey. The presence of the chair in the PET scanner caused negligible attenuation of radiation, allowing simultaneous acquisition of dynamic data from the subject's brain and heart. We conclude that a styrofoam primate chair is an ideal tool to measure blood and brain data from a rhesus monkey with PET. Invasiveness to the animal is reduced, as well as experimenter time.     

5th Annual Monoclonal Antibodies Conference: March 24–25, 2009, London,UK

The conference, which was organized by Visiongain and held at the BSG Conference Center in London, provided an excellent opportunity for participants to exchange views on the development, production, and marketing of therapeutic antibodies, and discuss the current business environment. The conference included numerous interactive panel and group discussions on topics such as isotyping for therapeutic antibodies (panel chair: Nick Pullen, Pfizer), prospects for fully human monoclonal antibodies (chair: Christian Rohlff, Oxford BioTherapeutics), perspectives on antibody manufacturing and development (chair: Bo Kara, Avecia), market impact and post-marketing issues (chair: Keith Rodgers, Bodiam Consulting), and angiogenesis inhibitors (chair: David Blakey, AstraZeneca).     

Effect of Furniture Weight on Carrying,Lifting, and Turning of Chairs and Desks among Elementary School Children

Rearranging furniture in elementary school classrooms encourages classroom activities. In elementary schools in Indonesia and some other developing countries, usually only one style of furniture is used for all children, and the furniture is heavy and oversized for younger children. This affects their ability to carry it. The objective of this study is to investigate the effects of elementary school furniture weight and children’s age on performance of three carrying tasks (carrying a chair, lifting and turning a chair on a desk, and carrying both a chair and a desk together), from the ergonomics point of view. A total of 42 schoolchildren (ages 6–9; 17 Indonesian, 25 Japanese) participated in this study. Two types of Japanese chairs (Chair A and B, weight: 3.2 kg and 3.9 kg), one type of Indonesian chair (Chair C, weight: 5.0 kg), and two types of desks (height: 58 cm and 68 cm) were used. Indonesian chairs took significantly longer time to carry than the two Japanese chairs, and there was a significant negative relationship between age and task time for Chairs B and C, but not Chair A. Success rates for lifting and turning the chair declined as age decreased and chair weight increased, but were not significantly influenced by desk height. Success rates for carrying a chair and desk together significantly decreased with heavier furniture. Children aged six showed an extremely low success rate in almost all conditions. In conclusion, children’s ability to carry furniture is affected by their age and furniture characteristics, especially weight. In order to encourage classroom activities in elementary school, school furniture should be of appropriate weight. Supervision for younger children is required during classroom furniture arrangement.     

Effects of repeated chair restraint on physiological values in the rhesus monkey (Macaca mulatta)

The purpose of this study was to examine the effects of repeated chair restraint on some physiological values in the rhesus monkey. Although heart rate and blood pressure increased significantly at the onset of chair restraint, these increased values gradually decreased with repetition of restraint as well as with the lapse of time after restraining. Finally, no elevation of these levels was detected after repetitions lasting eight hours per day for five days. Plasma cortisol, CK and GOT values also showed similar trends. These elevated physiological values at the onset of chair restraint seemed to be due to high sympathetic tone and muscular activity used to try to avoid the restraint. It is concluded that repeated chair restraint has an accommodative component in monkeys resulting in the return of some elevated physiological values to the normal level.     

Using topological equivalence to discover stable control parameters in biodynamic systems

In order to better understand the mechanisms that contribute to low back pain, researchers have developed mathematical models and simulations. A mathematical model including neuromuscular feedback control is developed for a person balancing on an unstable sitting apparatus, the wobble chair. When the application of a direct method fails to discover appropriate controller gain parameters for the wobble chair, we show how topological equivalence can be used to indirectly identify appropriate parameter values. The solution is found by first transforming the wobble chair into the Acrobot, another member of the same family of topologically equivalent dynamical systems. After finding appropriate gain parameters for the Acrobot, a continuous transformation is performed to convert the Acrobot back to the wobble chair, during which the gain parameters are adjusted to maintain stability. Thus, we demonstrate how topological equivalence can be used to indirectly solve a problem that was difficult to solve directly.     

Using topological equivalence to discover stable control parameters in biodynamic systems

In order to better understand the mechanisms that contribute to low back pain, researchers have developed mathematical models and simulations. A mathematical model including neuromuscular feedback control is developed for a person balancing on an unstable sitting apparatus, the wobble chair. When the application of a direct method fails to discover appropriate controller gain parameters for the wobble chair, we show how topological equivalence can be used to indirectly identify appropriate parameter values. The solution is found by first transforming the wobble chair into the Acrobot, another member of the same family of topologically equivalent dynamical systems. After finding appropriate gain parameters for the Acrobot, a continuous transformation is performed to convert the Acrobot back to the wobble chair, during which the gain parameters are adjusted to maintain stability. Thus, we demonstrate how topological equivalence can be used to indirectly solve a problem that was difficult to solve directly.     

Effects of chair restraint on plasma enzyme values in the rhesus monkey (Macaca mulatta)

The purpose of this paper was to examine the effect of chair restraint on plasma enzyme values in the rhesus monkey. Six monkeys were restrained to the monkey chair for eight hours. Creatine phosphokinase (CK) value increased significantly three hours after the onset of restraint and LDH value did eight hours after the onset of restraint. The increase in CK, GOT and GPT values continued for 1 or 2 days after the release from restraint. On the other hand, these plasma enzyme values in non-restraint monkeys showed almost no changes. These results indicate that it is necessary to establish a proper method for the adjustment to chair restraint in the rhesus monkey.     

Functional evaluation of the TKA patient using the coordination and variability of rising.

A kinematic analysis of the knee function is important for the evaluation of total knee arthroplasties (TKA). We used the coordination and variability of rising from a chair as functional knee parameters. Twelve knee patients were measured prior to surgery (=pre-TKA group) and one year after surgery (=post-TKA group). A group of 15 healthy, age-matched subjects was selected as control group. The WOMAC questionnaire, frequently used by orthopaedic surgeons, was administered prior to the test. The test consisted of 10 times rising from a low chair and 10 times from a high chair. Knee and hip angles and angular velocities were measured with electrogoniometers. The relative phase (=MRP) between hip and knee was a measure for the coordination of rising and the standard deviation of the relative phase of the 10 trials (=SRP) was a measure for the variability. The coordination and variability of rising of the TKA patients were compared to the control group, and the relationship with the WOMAC questionnaire was calculated. The coordination of rising from a high chair and the variability of rising from both chair heights were significantly different for the pre-TKA group compared to the control group (p<0.05). The post-TKA group showed no significant differences with the control group, which indicates a functional recovery after TKA implantation. The functional parameters correlated adequately with the subjective WOMAC questionnaire. This study showed that our method is an objective measure of functionality and it will be worthwhile to use it as an additional evaluation tool.     

Solid and solution state conformation of 1L-1-O-acetyl-2,3:5,6-di-O-isopropylidene-chiro-inositol

The X-ray crystal structure of 1L-1-O-acetyl-2,3:5,6-di-O-isopropylidene-chiro-inositol is described. The inositol ring deviates considerably from the ideal chair conformation to a flattened chair. A comparison of its conformation in solution with that in solid was made by the use of 1H NMR. This conformational analysis revealed that the title compound adopts similar conformations in solid state and in solution states irrespective of solvent polarity.     

A Flexible Restraint Chair for the Cynomolgus Monkey (Macaca fascicularis)1

We have found that commercial restraint chairs suitable for the rhesus monkey (Macaca mulatta) cause severe physical distress to many cynomolgus monkeys (Macaca fascicularis). A new restraint chair has therefore been designed specifically for the cynomolgus. The key features of the chair are an angled neck piece, a large opening to provide free movement for the tail, a soft waist restraint, and a level surface for both the heels and ischial pads. This new chair is not only suitable for the cynomolgus monkey but may also be more comfortable for the rhesus monkey than standard commercial chairs.     

Design for the Next Generation: Incorporating Cradle-to-Cradle Design into Herman Miller Products

In the late 1990s, office furniture manufacturer Herman Miller, Inc., entered into a collaboration with architect William McDonough to create a system for designing cradle-to-cradle products. This collaboration led to the creation of a tool—the Design for Environment (DfE) product assessment tool—that evaluates progress towards cradle-to-cradle products. The first product Herman Miller designed using the DfE product assessment tool was the Mirra chair. Over the course of the chair's development, the DfE process generated a number of design changes, including selecting a completely different material for the chair's spine, increasing recycled content in chair components, eliminating all PVC (polyvinyl chloride) components, and designing the chair for rapid disassembly using common tools.
The areas of greatest success in designing the Mirra chair for the environment were the increased use of recyclable parts and increased ease of disassembly, whereas the areas of greatest challenge were increasing recycled content and using materials with a green chemistry composition. The success in recyclability reflects the use of metals, materials that have a well-established recycling infrastructure. The success in disassembly reflects the high degree of control that Herman Miller has over product assembly. The challenge to increasing recycled content is the use of plastics in chairs. Unlike the metals, which all contain some recycled content, most plastics are made from virgin polymers. The challenge to improving materials chemistry is the limited range of green chemicals and materials on the market.
The Mirra chair exemplifies the value of incorporating the environment into design and the need for tools to benchmark progress, as well as the challenges of creating a truly cradle-to-cradle product. Herman Miller recognizes that working toward cradle-to-cradle products is a journey that will involve continuous improvement of its products.     

Life cycle assessment of commercial furniture: a case study of Formway LIFE chair

Background, aims and scope  The environmental aspects of companies and their products are becoming more significant in delivering competitive advantage. Formway Furniture, a designer and manufacturer of office furniture products, is a New Zealand-based company that is committed to sustainable development. It manufactures two models of the light, intuitive, flexible and environmental (LIFE) office chair: one with an aluminium base and one with a glass-filled nylon (GFN) base. It was decided to undertake a life cycle assessment (LCA) study of these two models in order to: (1) determine environmental hotspots in the life cycle of the two chairs (goal 1); (2) compare the life cycle impacts of the two chairs (goal 2); and (3) compare alternative potential waste-management scenarios (goal 3). The study also included sensitivity analysis with respect to recycled content of aluminium in the product. Materials and methods  The LIFE chair models consist of a mix of metal and plastic components manufactured by selected Formway suppliers according to design criteria. Hence, the research methodology included determining the specific material composition of the two chair models and acquisition of manufacturing data from individual suppliers. These data were compiled and used in conjunction with pre-existing data, specifically from the ecoinvent database purchased in conjunction with the SimaPro7 LCA software, to develop the life cycle inventory of the two chair models. The life cycle stages included in the study extended from raw-material extraction through to waste management. Impact assessment was carried out using CML 2 baseline 2000, the methodology developed by Leiden University’s Institute for Environmental Sciences. Results  This paper presents results for global warming potential (GWP100). The study showed a significant impact contribution from the raw-material extraction/refinement stage for both chair models; aluminium extraction and refining made the greatest contribution to GWP100. The comparison of the two LIFE chair models showed that the model with the aluminium base had a higher GWP100 impact than the model with the GFN base. The waste-management scenario compared the GWP100 result when (1) both chair models were sent to landfill and (2) steel and aluminium components were recycled with the remainder of the chair sent to landfill. The results showed that the recycling scenario contributed to a reduced GWP100 result. Since production and processing of aluminium was found to be significant, a sensitivity analysis was carried out to determine the impact of using aluminium with different recycled contents (0%, 34% and 100%) in both waste-management scenarios; this showed that increased use of recycled aluminium was beneficial. The recycling at end-of-life scenarios was modelled using two different end-of-life allocation approaches, i.e. consequential and attributional, in order to illustrate the variation in results caused by choice of allocation approach. The results using the consequential approach showed that recycling at end-of-life was beneficial, while use of the attributional method led to a similar GWP100 as that seen for the landfill scenario. Discussion  The results show that the main hotspot in the life cycle is the raw-material extraction/refinement stage. This can be attributed to the extraction and processing of aluminium, a material that is energy intensive. The LIFE chair model with the aluminium base has a higher GWP100 as it contains more aluminium. Sensitivity analysis pertaining to the recycled content of aluminium showed that use of aluminium with high recycled content was beneficial; this is because production of recycled aluminium is less energy intensive than production of primary aluminium. The waste-management scenario showed that recycling at end-of-life resulted in a significantly lower GWP100 than landfilling at end-of-life. However, this result is dependent upon the modelling approach used for recycling. Conclusions  With respect to goal 1, the study found that the raw-material extraction/refinement stage of the life cycle was a significant factor for both LIFE chair models. This was largely due to the use of aluminium in the product. For goal 2, it was found that the LIFE chair model with the aluminium base had a higher GWP100 than the GFN model, again due to the material content of the two models. Results for goal 3 illustrated that recycling at end-of-life is beneficial when using a system expansion (consequential) approach to model recycling; if an attributional ‘cut-off’ approach is used to model recycling at end-of-life, there is virtually no difference in the results between landfilling and recycling. Sensitivity analysis pertaining to the recycled content of aluminium showed that use of higher recycled contents leads to a lower GWP100 impact. Recommendation and perspectives  Most of the GWP100 impact was contributed during the raw-material extraction/refinement stage of the life cycle; thus, the overall impact of both LIFE chair models may be reduced through engaging in material choice and supply chain environmental management with respect to environmental requirements. The study identified aluminium components as a major contributor to GWP100 for both LIFE chair models and also highlighted the sensitivity of the results to its recycled content. Thus, it is recommended that the use of aluminium in future product designs be limited unless it is possible to use aluminium with a high recycled content. With respect to waste management, it was found that a substantial reduction in the GWP100 impact would occur if the chairs are recycled rather than landfilled, assuming an expanding market for aluminium. Thus, recycling the two LIFE chair models at end-of-life is highly recommended.     

Conformation of the mucopolysaccharides. X-ray fibre diffraction of heparin

Oriented films of the sodium salt of heparin crystallize in a triclinic unit cell. The X-ray diffraction results favour a tetrasaccharide covalent repeating sequence but the measured molecular repeat of 1.59nm is inconsistent with all alpha-(1-->4)(1ax-->4eq)-glycosidic linkages as generally accepted. Three models are proposed for the molecular shape of heparin, which depend on the chair conformation adopted by the hexuronic acid moieties. Model I has both uronic acids in the C1 chair form, model II has one uronic acid in each of the C1 and 1C chairs and model III has both in the 1C chair form. The merits of these models are discussed.     

Crystal structure of 1L-1,2:4,5-di-O-isopropylidene-allo-inositol: a comparison of its conformation in solid and solution states

The X-ray crystal structure of 1l-1,2:4,5-di-O-isopropylidene-allo-inositol, is described. The inositol ring deviate slightly from the ideal chair conformation to a flattened chair. A comparison of its conformation in solution with that in solid was made by the use of 1H NMR. This conformational analysis revealed that the title compound adopts similar conformations in solid state and in solution in low polar solvents like benzene and CHCl3 while in high polar solvents such as Me2SO, the solid state conformation is not retained.     

Effects of sagittal postural adjustments on seat reaction load

Wheelchair-dependent subjects often adopt a passive sitting posture and suffer from sitting acquired pressure ulcers (PU) that mainly occur when high buttock pressures sustain for a longer period of time. Body posture directly influences seating load and proper postural change is therefore essential. Many subjects cannot reposition themselves and seating systems that adjust sitting posture can regulate seating load and potentially diminish the risk to develop PU. We describe a mechanism for postural adjustments and investigated the influence of seat inclination (1), pelvis rotation (2) and chair recline (3) on buttock load. We developed an experimental simulator chair containing the concept to adjust body posture in the sagittal plane. Measurements involved quasi-static actuated chair movements in which chair configuration, buttock interface pressure and seating forces were simultaneously measured. Significant effects with high coefficients of determination (r(2)>0.8) were found for seating force, centre of pressure and sacral load. We conclude that a combination of independent pelvis rotation and seat inclination is effective to regulate the net buttock shear force and the sacral interface pressure in healthy subjects. Whether both techniques are also applicable in subjects without postural stability is still to be evaluated.     

Mechanics of a constrained chair-rise

A sit-to-stand task is analyzed by a method which estimates the segmental and whole body center of mass (CoM) kinematics and kinetics using bilateral whole body kinematic data from nine healthy young female subjects. The sit-to-stand, or chair-rise, task is constrained with regard to chair height, pace, initial lower limb position and arm use. The chair-rise maneuver is divided into four phases; (1) the flexion momentum phase; (2) the momentum transfer phase; (3) the vertical extension phase; and (4) the stabilization phase; the first three are examined in detail here. The momentum transfer phase, which immediately follows lift-off from the seat of the chair, is the most dynamic portion of the event, demanding a high degree of coordination. This maneuver is analyzed in order to determine if trunk movement is used only to position the body center of gravity or if the trunk motion generates momentum which is important during the brief but critical period of dynamic equilibrium immediately following lift-off from the chair. Our evidence points to the latter case and indicates that inter-segmental momentum transfer is possible during this period.     

Endotracheal intubation with airtraq? versus storz? videolaryngoscope in children younger than two years - a randomized pilot-study

Background

Beach chair positioning during general anesthesia is associated with a high incidence of cerebral desaturation; poor neurological outcome is a growing concern. There are no published data pertaining to changes in cerebral oxygenation seen with increases in the inspired oxygen fraction or end-tidal carbon dioxide in patients anesthetized in the beach chair position. Furthermore, the effect anesthetic agents have has not been thoroughly investigated in this context. We plan to test the hypothesis that changes in inspired oxygen fraction or end-tidal carbon dioxide correlate to a significant change in regional cerebral oxygenation in anesthetized patients in beach chair position. We will also compare the effects that inhaled and intravenous anesthetics have on this process.

Methods/design

This is a prospective within-group study of patients undergoing shoulder arthroscopy in the beach chair position which incorporates a randomized comparison between two anesthetics, approved by the Institutional Review Board of the University of Michigan, Ann Arbor. The primary outcome measure is the change in regional cerebral oxygenation due to sequential changes in oxygenation and ventilation. A sample size of 48 will have greater than 80% power to detect an absolute 4-5% difference in regional cerebral oxygenation caused by changes in ventilation strategy. The secondary outcome is the effect of anesthetic choice on cerebral desaturation in the beach chair position or response to changes in ventilation strategy. Fifty-four patients will be recruited, allowing for drop out, targeting 24 patients in each group randomized to an anesthetic. Regional cerebral oxygenation will be measured using the INVOS 5100C monitor (Covidien, Boulder, CO). Following induction of anesthesia, intubation and positioning, inspired oxygen fraction and minute ventilation will be sequentially adjusted. At each set point, regional cerebral oxygenation will be recorded and venous blood gas analysis performed. The overall statistical analysis will use a repeated measures analysis of variance with Tukey??s HSD procedure for post hoc contrasts.

Discussion

If simple maneuvers of ventilation or anesthetic technique can prevent cerebral hypoxia, patient outcome may be improved. This is the first study to investigate the effects of ventilation strategies on cerebral oxygenation in patients anesthetized in beach chair position.

Trial registration

NCT01535274     

Efficient Cooperative Restraint Training With Rhesus Macaques

It is sometimes necessary for nonhuman primates to be restrained during biomedical and psychosocial research. Such restraint is often accomplished using a “primate chair.” This article details a method for training adult rhesus macaques to cooperate with a chair restraint procedure using positive and negative reinforcement. Successful training was accomplished rapidly in approximately 14 training days. The success of this training technique suggests that this method represents a refinement to traditional techniques. Further, this method worked effectively for animals previously deemed unfit for traditional pole-and-collar training.