Correlates of Balance and Aerobic Indices in Lower-Limb Prostheses Users on Arm Crank Exercise.

BACKGROUND: The HUMAC Balance System (HBS) offers valid measurement of balance, and the arm crank exercise test (ACE) is a valid measure of physiological capacity. Neither have been used to evaluate associations between balance and physiological capacity in lower-limb amputees. METHODS: Thirty-five participants with lower-limb amputations were recruited. Standing balance (center of pressure) was evaluated during eyes opened (EO) and eyes closed (EC) conditions using the HBS. Participants performed ACE graded exercise testing (GXT) to evaluate aerobic capacity. Spearman's rho was used to identify relationships between variables. Cut-points for three groups were generated for time on ACE. Mann-Whitney U tests were used to explore significant differences in variables of balance and ACE between low and high performers. RESULTS: Relationships between variables of eyes open displacement (EOD), eyes open velocity (EOV), eyes closed displacement (ECD), and eyes closed velocity (ECV) were significant (p < 0.05), and high performers with EO also performed best with EC. Longer exercise times were significantly associated with increased HRpeak, VO2peak, VEpeak, and RERpeak (p < 0.05). HRpeak (143.0 ± 30.6 b/min), VO2peak (22.7 ± 7.9 and 10.6 ± 4.7 mL/kg/min), VEpeak (80.2 ± 22.2 and 33.2 ± 12.7 L/min), and RERpeak (1.26 ± 0.08 and 1.13 ± 0.11) were significantly greater in high performers than low performers, respectively (p < 0.05). There was no significant association among VO2peak and any balance task variables; however, there were significant associations between some balance and physiological variables. CONCLUSIONS: Findings differentiated high and low performers; however, participants were still well below able-bodied norms of physical capacity. Training to mitigate deconditioning is suggested.

Quantifying Step Count and Oxygen Consumption with Portable Technology during the 2-Min Walk Test in People with Lower Limb Amputation.

Step counts and oxygen consumption have yet to be reported during the 2-min walk test (2MWT) test in persons with lower-limb amputations (LLA). The purpose of this study was to determine step counts and oxygen consumption during the 2MWT in LLA. Thirty-five men and women walked for two minutes as quickly as possible while wearing activity monitors (ActiGraph Link on the wrist (LW) and ankle (LA), Garmin vivofit®3 on the wrist (VW) and ankle (VA), and a modus StepWatch on the ankle (SA), and a portable oxygen analyzer. The StepWatch on the ankle (SA) and the vivofit3 on the wrist (VW) had the least error and best accuracy of the activity monitors studied. While there were no significant differences in distance walked, oxygen consumption (VO2) or heart rate (HR) between sexes or level of amputation (p > 0.05), females took significantly more steps than males (p = 0.034), and those with unilateral transfemoral amputations took significantly fewer steps than those with unilateral transtibial amputations (p = 0.023). The VW and SA provided the most accurate step counts among the activity monitors and were not significantly different than hand counts. Oxygen consumption for all participants during the 2MWT was 8.9 ± 2.9 mL/kg/min, which is lower than moderate-intensity activity. While some may argue that steady-state activity has not yet been reached in the 2MWT, it may also be possible participants are not walking as fast as they can, thereby misclassifying their performance to a lower standard.

Confined acoustic line modes within a glide-symmetric waveguide.

Confined coupled acoustic line-modes supported by two parallel lines of periodic holes on opposite surfaces of a glide-symmetric waveguide have a hybrid character combining symmetric and anti-symmetric properties. These hybrid coupled acoustic line-modes have a near constant group velocity over a broad frequency range as no band gap is formed at the first Brillouin zone boundary. We show that the hybrid character of these confined modes is tuneable as a function of the spacing between the two surfaces. Further we explore how the band-gap reappears as the glide symmetry is broken.

The effect of abdominal exercise on abdominal fat.

The purpose of this study was to investigate the effect of abdominal exercises on abdominal fat. Twenty-four healthy, sedentary participants (14 men and 10 women), between 18 and 40 years, were randomly assigned to 1 of the following 2 groups: control group (CG) or abdominal exercise group (AG). Anthropometrics, body composition, and abdominal muscular endurance were tested before and after training. The AG performed 7 abdominal exercises, for 2 sets of 10 repetitions, on 5 d·wk(-1) for 6 weeks. The CG received no intervention, and all participants maintained an isocaloric diet throughout the study. Significance was set at p = 0.05 for all tests. There was no significant effect of abdominal exercises on body weight, body fat percentage, android fat percentage, android fat, abdominal circumference, abdominal skinfold and suprailiac skinfold measurements. The AG performed significantly greater amount of curl-up repetitions (47 ± 13) compared to the CG (32 ± 9) on the posttest. Six weeks of abdominal exercise training alone was not sufficient to reduce abdominal subcutaneous fat and other measures of body composition. Nevertheless, abdominal exercise training significantly improved muscular endurance to a greater extent than the CG.

Diffraction from the edge of a thin elastic half plane and implications for panel measurements.

Solutions for the diffraction of a plane wave from the edge of a semi-infinite, thin elastic plate are presented. A thin plate formulation that takes into account the coupling into both symmetric and antisymmetric waves on the plate is used. The symmetric contributions are found to be small for steel in water but can be significant for plastic plates. Expansions in terms of the fluid loading parameter are used in the far field of the edge to explore the effect of the diffraction from a single edge on transmission measurements. Examples for steel and polymethylmethacrylate in water are presented.

The validity and accuracy of wrist-worn activity monitors in lower-limb prosthesis users.

Purpose: To investigate the accuracy of consumer-grade wrist-worn activity monitors during over ground walking in persons using lower-limb prosthetics.Method: Thirty-two participants using lower-limb prosthetics (age = 49.7 ± 14.0 yrs, height = 176.1 ± 11.6 cm, weight = 87.8 ± 21.1 kg) were fitted with a Polar Loop, Fitbit Flex, MOVEBAND, Garmin Vivofit, and a Fitbit Charge on the right and left wrists as well as an Omron HJ-113 pedometer on the right and left hip, then walked 140 m at a self-selected pace on an indoor flat surface.Results: There were no significant differences between any of the respective right and left monitors, p > 0.05. When comparing step counts with actual step counts, Polar Loop (p = 0.001), Fitbit Flex (p = 0.001), and MOVEBAND (p = 0.001) were significantly lower than actual step counts. No significant differences existed between the remaining monitors and actual step counts (p > 0.05). Omron incurred the least error (0.6%), followed by Garmin Vivofit (1.3%) and Fitbit Charge (3.6%), with greatest error in the MOVEBAND (21.4%) and Polar Loop (13.1%). Bland-Altman plots suggest Garmin Vivofit to have the least error along with tightest agreement among the wrist-worn activity monitorsConclusion: When considering the use of consumer-grade wrist-worn activity monitors for assessing step counts in persons using lower-limb prostheses, the Garmin Vivofit seems to be the best option followed by Fitbit Charge.Implications for rehabilitationThis study shows that despite potential of altered gait, some consumer-grade activity monitors can track over ground walking quite well.Clinicians and researchers can use these devices to track activity and prosthetic compliance in their patients.

Expression of endothelial intercellular adhesion molecule-1 is determined by genotype: effects on efficiency of leukocyte adhesion to human endothelial cells.

Two biallelic polymorphisms, previously described in the human intercellular adhesion molecule (ICAM)-1 gene at codon 241 (glycine [G] to arginine [R] substitution) and codon 469 (glutamic acid [E] to lysine [K] substitution) have been associated with a number of diseases including myocardial infarction, transplant rejection, and diabetes. However, the functional significance of these polymorphisms has not been determined. ICAM-1 cell surface expression and ICAM-1-mediated leukocyte adhesion were investigated using Cos7 transfected with ICAM-1 polymorphic variants or human umbilical vein endothelial cells (HUVEC) of different ICAM-1 genotypes. There was significantly higher expression of surface ICAM-1 on Cos7 transfected with a plasmid encoding the GE (G241/E469) ICAM-1 variant or untreated HUVEC of GEGE (G241/E469 homozygous genotype). ICAM-1-mediated adhesion of peripheral blood mononuclear cells (PBMC) to GE-Cos7 cells or TNF-treated GEGE HUVEC was significantly increased. However, there was no significant difference in adhesion of PBMC to recombinant ICAM-1 of each polymorphic variant plated onto plastic wells. We conclude that the GE genotype of ICAM-1 is associated with greater cell surface expression of ICAM-1, which in turn leads to greater adhesion of leukocytes. This may explain the previously described associations of ICAM-1 polymorphisms with chronic inflammatory disease.

Acoustic characterization of panel materials under simulated ocean conditions using a parametric array source.

A technique for evaluating the underwater acoustic performance of panels under simulated ocean conditions in a laboratory test facility is described. The method uses a parametric array as a source of sound within a test vessel capable of simulating ocean depths down to 700 m and water temperatures from 2 to 35 degrees C. The reflection loss and transmission loss of the test panel may be determined at frequencies from a few kilohertz to 50 kHz. The use of the parametric array enables wideband measurements to be undertaken with short-duration pulses and reduces the effects of diffraction from the panel edges. An acoustic filter is used to truncate the array in order to provide a source-free measurement region and to simplify the measurement process. The difficulties of establishing a parametric array in the confined space of the vessel are outlined, and the experimental procedures adopted are described. The techniques were validated by undertaking measurements on two test objects that have predictable behavior. The potential of the technique is also illustrated with experimental results for test panels for hydrostatic pressures up to 2.8 MPa. An extensive discussion of the measurement limitations is included.

Leg compressions improve ventilatory efficiency while reducing peak and post exercise blood lactate, but does not improve perceived exertion, exercise economy or aerobic exercise capacity in endurance-trained runners.

PURPOSE: The objective of this study was to determine if leg compressions would alter cardiorespiratory and perceived exertion measures during rest, submaximal and maximal exercise in endurance-trained runners. METHOD: Thirteen young, endurance trained runners (10 males, 20.9±3y, 58.9±5.7mlkgmin-1) completed a randomized design, leg compressions and non-compression control condition. The incremental graded exercise test consisted of baseline rest and submaximal intensities at 23%, 70%, 75%, 85% and then a progressive increase to 100% VO2max. Running economy (RE), rating of perceived exertion (RPE), breathing rate (BR), heart rate (HR), ventilation (VE), blood lactate, VO2max and ventilatory efficiency (VE/VO2) were the primary outcome variables. RESULTS: Relative to the control condition, VO2 at rest, during submaximal and at max were not different. Additionally, RE, RPE, BR, and HR were similar under both conditions. Leg compressions reduced lactate at VO2max by 11% (P<0.05) and at 10min post-exercise recovery by 18% (P<0.01). Additionally, peak VE was significantly reduced in the compression condition by 8% (P<0.0001) relative to the control condition. Ventilatory efficiency was improved in compressions compared to control condition at 85 and 100% VO2max (condition×time interaction, P<0.0001). CONCLUSION: These data suggest that leg compressions do not alter RE, RPE, BR, HR, or VO2, during exercise. However, compressions may be beneficial for submaximal and maximal ventilatory efficiency while improving lactate clearance at VO2max and during recovery in trained runners.

Detection and clinical relevance of antibodies after transplantation.

Until recently, the role of antibodies in graft failure has been hampered by poor methods of defining specificity. Development of solid phase assays using purified major histocompatibility complex (MHC) molecules has greatly advanced our ability to monitor anti-human leukocyte antigen (HLA) antibodies in patients and to distinguish between HLA and non-HLA antibodies. The purpose of this chapter is to describe the methods for detecting antibodies and what we have learned in recent years regarding the role of well-defined antibodies to HLA and non-HLA antigens. Use of the complement-dependent lymphocytotoxic test was instrumental in defining patients who are sensitized to donor HLA antigens, and it still plays a major role in avoiding transplantation of organs into sensitized patients. However, solid phase assays are more useful for following patients posttransplant. A major advance has been the demonstration that anti-MHC class II antibodies are made late after transplantation and contribute to late graft failure. This has been demonstrated for renal and lung transplantation, but has not yet been confirmed for other organs. Clearer definition of non-HLA antibodies has been achieved, such as the autoantigen vimentin and MHC I-related chain A. Experimental studies using minor mismatched strain combinations confirm that non-HLA antibodies bind to donor endothelial cells; these antibodies seem to cause apoptosis but not complement-mediated lysis.

Synthesis and Characterization of bis(Tetrahydrofurfuryl) Ether.

Invited for this month's cover are researchers from the Naval Air Warfare Center Weapons Division (USA). The cover picture shows the elusive symmetric molecule bis (tetrahydrofurfuryl) ether (BTHFE) in the making. For more details, read the full text of the Communication at 10.1002/open.201600013.

Synthesis and Characterization of bis(Tetrahydrofurfuryl) Ether.

Despite the availability of a large number of alkyl tetrahydrofurfuryl ethers that have a wide range of applications, pure bis(tetrahydrofurfuryl) ether (BTHFE) has not been previously synthesized. Here, we report the synthesis of BTHFE (consisting of the RR, SS, and meso stereoisomers) at greater than 99 % purity from tetrahydrofurfuryl alcohol, using (tetrahydrofuran-2-yl)methyl methanesulfonate as an intermediate. Additionally, we demonstrate that BTHFE can be used as a non-volatile solvent in poly(3,4-propylenedioxythiophene)-based supercapacitors. Supercapacitor devices employing solutions of the ionic liquid 1-ethyl-3-methyl-imidizolium bis(trifluoromethylsulfonyl)imide in BTHFE display similar performances to those prepared by using the neat ionic liquid as an electrolyte, although solution-based devices exhibit a somewhat higher resistance.

Risk of lymphoid neoplasia after cardiothoracic transplantation: the influence of underlying disease and human leukocyte antigen type and matching.

BACKGROUND: It has been known for more than 20 years that there is an increased risk of lymphoid neoplasia after cardiothoracic transplantation. Recent studies have demonstrated the importance of primary Epstein-Barr virus (EBV) infection and type of immunosuppressive therapy to the cause of these neoplasms, but the contribution of other factors remains equivocal. METHODS: The authors followed 1,562 patients undergoing cardiothoracic transplantation at Harefield Hospital, United Kingdom, and used standard cohort methods of analysis to examine whether posttransplant lymphoma risk was related to the underlying disease requiring transplantation or the human leukocyte antigen (HLA) type and matching. Lymphomas were categorized into EBV-associated lymphoproliferative disease (LPD) and EBV-negative non-Hodgkin's lymphoma (NHL), and the authors carried out separate analyses of these. RESULTS: The authors found no significant association between the underlying disease necessitating transplantation and the risk of lymphoid neoplasia. There was also no evidence of a relation of lymphoma risk with the presence or absence of any particular HLA antigen, although significant protective effects of HLA-B14 and -B57 were found when analyses were conducted without adjustment for multiple testing. Risk of LPD was not associated with degree of HLA mismatching, but there was a significant effect of mismatching on risk of EBV-negative tumors. CONCLUSIONS: The differential effect of HLA mismatching on the risks of LPD and EBV-negative NHL provides further evidence that these two tumors are distinct etiologic entities. The authors' results suggest that the immunologic cause of EBV-negative NHL may be different from that of LPD. Investigation of the relation of risk of EBV-negative NHL to degree of immunosuppression is needed.

Involvement of nitric oxide synthase in skeletal muscle adaptation to chronic overload.

The purpose of this study was to determine the necessity of nitric oxide (NO) for hypertrophy and fiber-type transition in overloaded (OL) skeletal muscle. Endogenous NO production was blocked by administering N(G)-nitro-L-arginine methyl ester (L-NAME; 0.75 mg/ml; approximately 100 mg x kg-1 x day-1) in drinking water. Thirty-eight female Sprague-Dawley rats (approximately 250 g) were randomly divided into four groups: control-nonoverloaded (Non-OL), control-OL, L-NAME-Non-OL, and L-NAME-OL. Chronic overload of the plantaris was induced bilaterally by surgical removal of the gastrocnemius and soleus. Rats in the Non-OL groups received sham surgeries. L-NAME treatment began 24 h before surgery and continued until the rats were killed 14 days postsurgery. Although OL induced hypertrophy in both control (+76%) and L-NAME (+39%) conditions (P < 0.05), mean plantaris-to-body mass ratio in the L-NAME-OL group was significantly lower (P < 0.05) than that in the control-OL group. Microphotometric analysis of histochemically determined fiber types revealed increases in cross-sectional area (P < 0.05) for all fiber types (types I, IIA, and IIB/X) in the OL plantaris from control rats, whereas L-NAME-OL rats exhibited increases only in type I and IIB/X fibers. SDS-PAGE analysis of myosin heavy chain (MHC) composition in the plantaris indicated a significant (P < 0.05) OL effect in the control rats. Specifically, the mean proportion of type I MHC increased 6% (P < 0.05), whereas the proportion of type IIb MHC decreased approximately 9% (P < 0.05). No significant OL effects on MHC profile were observed in the L-NAME rats. These data support a role of NO in overload-induced skeletal muscle hypertrophy and fiber-type transition.

De novo donor HLA-specific antibodies predict development of bronchiolitis obliterans syndrome after lung transplantation.

BACKGROUND: Bronchiolitis obliterans syndrome (BOS) is the major cause of late graft failure after lung transplantation. The objective was to determine whether de novo donor human leukocyte antigen (HLA)-specific antibodies (DSA) are associated with the development of BOS or patient survival. Data were analyzed from 188 lung transplant recipients with a follow-up period up to 8 years. METHODS: HLA antibody monitoring was performed at 3-month intervals post-transplant at routine outpatient clinic attendances and during the investigation of any acute deterioration. HLA antibody data were available for 148 patients; 66 (45%) had produced HLA antibodies after transplant, of which 38 (26%) were DSA and 28 (19%) non-donor-specific HLA antibodies. RESULTS: De novo DSA was associated with development of BOS Stage 1 (BOS1; hazard ratio [HR] = 2.302, p = 0.0015), BOS2 (HR = 3.627, p < 0.0001) and BOS3 (HR = 5.736, p < 0.0001). De novo persistent DSA correlated strongly with shorter time to onset of BOS3 (HR = 6.506, p = 0.0001). There was a significant reduction in patient survival associated with de novo DSA (HR = 1.886, p = 0.047). In multivariable analyses, de novo DSA was an independent predictor for development of all stages of BOS as well as an independent predictor of poor patient survival. CONCLUSIONS: De novo DSA is a major risk factor for progression to BOS and shorter patient survival. Treatments to remove antibodies or limit antibody-mediated damage could be considered when DSA are first detected. However, a randomized, controlled trial of treatment options would enable a clearer understanding of the benefits, if any, of antibody-removal therapies.

Pre-transplant donor HLA-specific antibodies: characteristics causing detrimental effects on survival after lung transplantation.

BACKGROUND: The impact of Luminex-detected HLA antibodies on outcomes after lung transplantation is unclear. Herein we have undertaken a retrospective study of pre-transplant sera from 425 lung transplants performed between 1991 and 2003. METHODS: Pre-transplant sera, originally screened by complement-dependent cytotoxicity (CDC) assays, were retrospectively tested for the presence of HLA-specific antibodies using HLA-coated Luminex beads and C4d deposition on Luminex beads. The results were correlated with graft survival at 1 year. RESULTS: Twenty-seven patients were retrospectively identified as having been transplanted against donor-specific HLA antibodies (DSA) and 36 patients against non-donor-specific HLA antibodies (NDSA). DSA-positive patients had 1-year survival of 51.9% compared with 77.8% for NDSA and 71.8% for antibody-negative patients (p = 0.029). One-year survival of patients with complement-fixing DSA was 12.5% compared with 62.5% for non-complement-fixing DSA, 75.8% for non-complement-fixing NDSA and 71.8% for antibody-negative patients (p < 0.0001). DSA-positive patients with mean fluorescence intensity (MFI) >5,000 had 1-year survival of 33.3% compared with 71.4% for MFI 2,000 to 5000 and 62.5% for MFI <2,000 (p = 0.0046). Multivariable analysis revealed DSA to be an independent predictor of poor patient survival within 1 year (p = 0.0010, hazard ratio [HR] = 3.569) as well as complement-fixing DSA (p < 0.0001, HR = 11.083) and DSA with MFI >5,000 (p = 0.0001, HR = 5.512). CONCLUSIONS: Pre-formed DSA, particularly complement-fixing DSA, and high MFI are associated with poor survival within the first year after lung transplantation. Risk stratification according to complement fixation or MFI levels may allow for increased transplantation in sensitized patients.

Poly(2,5-bis(N-Methyl-N-Hexylamino)Phenylene Vinylene) (BAM-PPV) as Pretreatment Coating for Aerospace Applications: Laboratory and Field Studies.

In this study, an electroactive polymer (EAP), poly(2,5-bis(N-methyl-N-hexylamino)phenylene vinylene) (BAM-PPV) was investigated as a potential alternative surface pretreatment for hexavalent chromium (Cr(VI))-based aerospace coatings. BAM-PPV was tested as a pretreatment coating on an aerospace aluminum alloy (AA2024-T3) substrate in combination with a non-Cr(VI) epoxy primer and a polyurethane Advanced Performance Coating (APC) topcoat. This testing was undertaken to determine BAM-PPV's adhesion, corrosion-inhibition, compatibility and survivability in laboratory testing and during outdoor field-testing. BAM-PPV showed excellent adhesion and acceptable corrosion performance in laboratory testing. The BAM-PPV aerospace coating system (BAM-PPV, non-Cr(VI) epoxy primer and polyurethane APC topcoat) was field tested for one year on the rear hatch door of the United States Air Force C-5 cargo plane. After one year of field testing there was no evidence of delamination or corrosion of the BAM-PPV aerospace coating system.

Role of anti-vimentin antibodies in renal transplantation.

BACKGROUND: The role of non-HLA antibodies in rejection is not clear. We investigate whether antibodies to vimentin are made after renal transplantation and if production is associated with interstitial fibrosis and tubular atrophy (IFTA). METHODS: In this retrospective study, sera from 70 recipients of renal allografts (40 controls, 30 IFTA) were studied. The biopsy diagnosis of interstitial fibrosis and tubular atrophy (IFTA) was based on random, cause-indicating biopsies. Sera were collected pretransplant and at 3 monthly intervals up to 5 years posttransplant or diagnosis of IFTA and assayed by ELISA for IgM and IgG anti-vimentin antibodies (AVA) and HLA antibodies. RESULTS: Mean titers of IgM AVA were higher at every year after transplantation compared with pretransplant for both IFTA and controls groups (P<0.001). There was no difference in the mean level of IgM AVA achieved by IFTA and control groups. The mean pretransplant levels of IgG AVA in the IFTA and control group were 18.2±11.7 and 11.0±8.1, respectively (P=0.001). There was a significant increase between the pretransplant mean levels of IgG AVA and the levels at years 1 to 4 in the IFTA group (years 1-3, P<0.0001, year 4 P=0.003) but not in the controls. There was no significant difference between the numbers of IFTA or control patients achieving a positive value (mean+2SD of pretransplant antibody titers) of IgM AVA (50% versus 37.5%, respectively) or IgG AVA (26.6% versus 12.5%, respectively). There was no association between production of HLA and AVA antibodies. CONCLUSION: Posttransplant production of IgM AVA is not associated with IFTA. The production of IgG AVA by a minority of IFTA patients suggests that in some individuals, IgG AVA may be involved in the pathology of IFTA.

Solid phase assay measuring C4d deposition to determine complement fixation by HLA-specific antibodies.

The definition of HLA-specific antibodies in solid organ transplant patients is a necessary tool for recipient selection prior to transplantation and monitoring for rejection post transplant. Solid phase assays can detect both complement fixing and non-complement fixing HLA-specific antibodies. Here we describe a method for determining the presence of complement fixing HLA-specific antibodies using a sensitive solid phase assay.

Influence of weight classification on walking and jogging energy expenditure prediction in women.

The purpose of this study was to determine the influence of weight classification on predicting energy expenditure (EE) in women. Twelve overweight (body mass index [BMI] = 25-29.99 kg/m(2)) and 12 normal-weight (BMI = 18.5-24.99 kg/m(2)) women walked and jogged 1,609 m at 1.34 ms(-1) and 2.23 ms(-1), respectively, while EE was assessed using indirect calorimetry and compared to several other prediction methods (American College of Sports Medicine [ACSM], 2010; Heyward, 2006; Léger & Mercier, 1984; McArdle, Katch, & Katch, 2006; Pandolf Givoni, & Goldman, 1978; van der Walt & Wyndham, 1973). More error occurred with overweight EE prediction compared to normal-weight EE prediction. The ACSM and Heyward methods for walking and the McArdle et al. method for jogging most accurately predicted EE for both groups. Weight classification influences EE prediction accuracy and, thus, is important to consider when using these prediction methods.