The effect of Providence night-time bracing on the sagittal profile in adolescent idiopathic scoliosis.

PURPOSE: Adolescent idiopathic scoliosis (AIS) is characterized by coronal scoliosis and often a sagittal hypokyphosis. The effect of bracing on the sagittal profile is not well understood. The aim of this study is to assess the effect of night-time bracing on the sagittal profile in patients with AIS. METHODS: We retrospectively included AIS patients with a main curve of 25-45° treated with a night-time brace in our institution between 2005 and 2018. Patients with estimated growth potential based on either Risser stage, hand X-rays, or menarchal status were included. Coronal and sagittal radiographic parameters were recorded at both brace- initiation and -termination. Patients were followed until surgery or one year after brace termination. Results were compared to a published cohort of full-time braced patients. RESULTS: One hundred forty-six patients were included. Maximum thoracic kyphosis (TK) increased 2.5° (± 9.7) (p = 0.003), corresponding to a 3.5-fold relative risk increase post bracing in TK compared to a full-time brace cohort. Twenty-seven percent (n = 36) of the patients were hypokyphotic (T4/T12 < 20°) at brace initiation compared with 19% (n = 26) at brace termination (p = 0.134). All other sagittal parameters remained the same at follow-up. We found no association between progression in the coronal plane and change in sagittal parameters. CONCLUSION: This is the first study to indicate that night-time bracing of AIS does not induce hypokyphosis. We found a small increase in TK, with a substantially lower risk of developing flat back deformity compared to full-time bracing. The coronal curve progression was not coupled to a change in TK.

The influence of night-time bracing on curve progression is not affected by curve magnitude in adolescent idiopathic scoliosis: a study of 299 patients.

BACKGROUND AND PURPOSE: The efficacy of bracing larger curves in adolescent idiopathic scoliosis (AIS) patients is uncertain. We aimed to assess the influence of night-time bracing in AIS patients with main curves exceeding 40° Cobb angle at brace initiation. METHODS: We reviewed AIS patients treated with nighttime braces between 2005 and 2018. Patients with curves ≥ 25° and estimated growth potential were included. Patients were monitored with radiographs from brace initiation until brace weaning at skeletal maturity. Patients were grouped based on curve magnitude at initial evaluation: a control group (25-39°) and a large-curves group (≥ 40°). Progression was defined as > 5° increase. RESULTS: We included 299 patients (control group, n = 125; large-curves group, n = 174). In the control group, 65 (52%) patients progressed compared with 101 (58%) in the large-curves group (P = 0.3). The lower-end vertebra (LEV) shifted distally post-bracing in 41 (23%) patients in the largecurves group. Patients with progressive large curves were younger (age 13.2 [SD 1.5] vs. 13.9 [SD 1.1], P = 0.009) and more premenarchal (n = 36 [42%] vs. n = 6 [9%], P < 0.001) compared with non-progressive large curves. CONCLUSION: Progression risk in patients with curves exceeding 40° treated with night-time bracing is similar to smaller curves. The LEV moved distally in almost one-fourth of the larger curves, possibly affecting fusion levels in cases of surgery.

Does Risser stage accurately predict the risk of curve progression in patients with adolescent idiopathic scoliosis treated with night-time bracing?

PURPOSE: Risser stage is widely used as a marker for skeletal maturity (SM) and thereby an indirect measure for the risk of progression of adolescent idiopathic scoliosis (AIS). The Scoliosis Research Society recommends bracing for Risser stages 0-2 as Risser stage 3 or above is considered low risk. Very few studies have assessed the risk of progression during bracing in Risser stages 3-4. The objective of the current study is to determine if Risser stages 3-4 provide a meaningful cutoff in terms of progression risk in patients with AIS treated with night-time bracing. METHODS: AIS patients treated with night-time brace from 2005 to 2018 with a Cobb angle between 25 and 40 degrees and Risser stages 0-4 were retrospectively included. Curve progression (> 5 degrees increase) was monitored until surgery or SM. Skeletal maturity was defined as either 2 years postmenarchal, no height development or closed ulnar epiphyseal plates on radiographs. RESULTS: One hundred and thirty-five patients were included (Risser stages 0-2: n = 86 and 3-4: n = 49). Overall, radiographic curve progression occurred in 52% while progression beyond 45 degrees was seen in 35%. The progression rate in the Risser 0-2 group was 60% and 37% in the Risser 3-4 group (p = 0.012). In multivariate logistic regression analysis, adjusted for Risser stages and age, only premenarchal status showed a statistically significant association with progression (OR: 2.68, 95%CI 1.08-6.67). CONCLUSION: Risser stage does not provide a clinically meaningful differentiation of progression risk in AIS patients treated with a night-time brace. Risk assessment should include other more reliable measures of skeletal growth potential.

Evaluation of Brace Treatment Using the Soft Brace Spinaposture: A Four-Years Follow-Up.

The braces of today are constructed to correct the frontal plane deformity of idiopathic adolescent scoliosis (AIS). The Spinaposture brace© (Spinaposture Aps, Copenhagen, Denmark) is a soft-fabric brace for AIS and is designed to enhance rotational axial stability by inducing a sagittal plane kyphotic correction. This prospective observational study evaluated the brace in fifteen patients with AIS. The initial average CA was 16.8° (SD: 2.8). They were followed prospectively every 3 to 6 months during their brace usage until skeletal maturity of 25 months and at long-term follow-up of 44 months. In- and out-of-brace radiographs were performed in six subjects at inclusion. This resulted in an immediate in-brace correction of 25.3 percent in CA (14.3°â†’10.8°) and induced a kyphotic effect of 14.9 percent (40.8°â†’47.9°). The average in-brace improvement at first follow-up was 4.5° in CA, and the CA at skeletal maturity was 11° (SD: 7.4°) and long-term 12.0° (SD: 6.8°). In conclusion, the Spinaposture brace© had an immediate in-brace deformity correction and a thoracic kyphotic effect. At skeletal maturity, the deformities improved more than expected when compared to that of the natural history/observation and similar to that of other soft braces. No long-term deformity progression was seen. To substantiate these findings, stronger designed studies with additional subjects are needed.

The relationship between age and fitness profiles in elite male ice hockey players.

BACKGROUND: The present study investigated relationships between age, body composition and performance in elite male ice hockey players. METHODS: 199 players performed off-ice tests (countermovement jump height (CMJ) and body composition) and on-ice tests (5-10-5 Pro Agility test, 30-m sprint test and the maximal Yo-Yo Intermittent Recovery Ice Hockey test (Yo-Yo IR1-IHMAX) for assessment of aerobic capacity. RESULTS: No overall correlations between age and performance were present except small-moderate positive associations between age and body- and muscle mass (r=0.24-0.30, P≤0.05). The youngest age group (YOU; 18-21 years) were 4-9% lighter than all other age groups and possessed 7% less muscle mass compared to the oldest players (OLD; 30-33 years) (P≤0.05), whereas no differences were present in body fat percentage. OLD were 2-3% inferior to the second youngest (SEC; 22-25 years) and mid-age group (MID; 26-29 years) in sprint and agility performance in addition to a 6-10% lower CMJ height (P≤0.05). The younger age groups differed only by a 7 and 5% better CMJ performance in MID compared to YOU and SEC, respectively (P≤0.05). In contrast, no differences were found in distance covered on the Yo-Yo IR1-IHmax. CONCLUSIONS: Only small-moderate associations between age and body composition were present unlike for the remaining performance parameters. Nevertheless, a consistently lower high-intensity exercise performance was evident in the oldest- and a lower body weight in the youngest players, whereas aerobic capacity was similar. This suggests that capabilities related to size, strength and power are the most critical parameters differing between young and old ice hockey players.

On-Ice and Off-Ice Fitness Profiles of Elite and U20 Male Ice Hockey Players of Two Different National Standards.

Vigh-Larsen, JF, Haverinen, MT, Panduro, J, Ermidis, G, Andersen, TB, Overgaard, K, Krustrup, P, Parkkari, J, Avela, J, Kyröläinen, H, and Mohr, M. On-ice and off-ice fitness profiles of elite and U20 male ice hockey players of two different national standards. J Strength Cond Res 34(12): 3369-3376, 2020-Differences in body composition and performance were investigated between elite and U20 male ice hockey players of 2 different national standards. One hundred seventy-nine players were recruited from the highest Finnish (n = 82) and Danish (n = 61) national level, as well as from 1 U20 team from Finland (n = 19) and Denmark (n = 17). Body composition and countermovement jump performance (CMJ) were measured off-ice in addition to on-ice assessments of agility, 10- and 30-m sprint performance, and endurance capacity (the maximal Yo-Yo Intermittent Recovery Level 1 Ice Hockey Test, Yo-Yo IR1-IHmax). Large differences in on-ice performances were demonstrated between Finnish and Danish elite players for agility, 10- and 30-m sprint performance (2-3%, P ≤ 0.05), and Yo-Yo IR1-IHmax performance (15%, P ≤ 0.05). By contrast, no differences (P > 0.05) were present between elite players for CMJ ability or body composition. However, elite players possessed more body and muscle mass than U20 players. Finally, the Finnish U20 cohort had a similar performance level as the Danish elite players and superior 10-m sprint performance, whereas the Danish U20 level was inferior to the other groups in every performance assessment (P ≤ 0.05). In conclusion, on-ice speed and endurance differ markedly between elite players of 2 different national standards with no distinction in body composition or CMJ ability. Moreover, the most consistent difference between U20 and senior elite players was related to body and muscle mass. These results highlight the usefulness of on-ice assessments and suggest the importance of on-ice high-intensity training in elite players in addition to training targeted the development of lean body mass in youth prospects.

Muscle Metabolism and Fatigue during Simulated Ice Hockey Match-Play in Elite Players.

PURPOSE: The present study investigated muscle metabolism and fatigue during simulated elite male ice hockey match-play. METHODS: Thirty U20 male national team players completed an experimental game comprising three periods of 8 × 1-min shifts separated by 2-min recovery intervals. Two vastus lateralis biopsies were obtained either during the game (n = 7) or pregame and postgame (n = 6). Venous blood samples were drawn pregame and at the end of the first and last periods (n = 14). Activity pattern and physiological responses were continuously monitored using local positioning system and heart rate recordings. Further, repeated-sprint ability was tested pregame and after each period. RESULTS: Total distance covered was 5980 ± 199 m with almost half the distance covered at high skating speeds (>17 km·h). Average and peak on-ice heart rate was 84% ± 2% and 97% ± 2% of maximum heart rate, respectively. Muscle lactate increased (P ≤ 0.05) more than fivefold and threefold, whereas muscle pH decreased (P ≤ 0.05) from 7.31 ± 0.04 pregame to 6.99 ± 0.07 and 7.13 ± 0.11 during the first and last periods, respectively. Muscle glycogen decreased by 53% postgame (P ≤ 0.05) with ~65% of fast- and slow-twitch fibers depleted of glycogen. Blood lactate increased sixfold (P ≤ 0.05), whereas plasma free fatty acid levels increased 1.5-fold and threefold (P ≤ 0.05) after the first and last periods. Repeated-sprint ability was impaired (~3%; P ≤ 0.05) postgame concomitant with a ~10% decrease in the number of accelerations and decelerations during the second and last periods (P ≤ 0.05). CONCLUSIONS: Our findings demonstrate that a simulated ice hockey match-play scenario encompasses a high on-ice heart rate response and glycolytic loading resulting in a marked degradation of muscle glycogen, particularly in specific sub-groups of fibers. This may be of importance both for fatigue in the final stages of a game and for subsequent recovery.

Fitness Characteristics of Elite and Subelite Male Ice Hockey Players: A Cross-Sectional Study.

Vigh-Larsen, JF, Beck, JH, Daasbjerg, A, Knudsen, CB, Kvorning, T, Overgaard, K, Andersen, TB, and Mohr, M. Fitness characteristics of elite and subelite male ice hockey players: A cross-sectional study. J Strength Cond Res 33(9): 2352-2360, 2019-The purpose was to evaluate fitness profiles in elite (age 23.5 ± 4.4 years) and subelite (age 19.4 ± 3.1 years) male ice hockey players. Twenty teams from the best (n = 164) and second-best (n = 132) Danish ice hockey division were assessed in-season using a field-test battery consisting of off-ice measurements of countermovement jump (CMJ) performance and body composition, as well as performance tests on the ice. These included the submaximal and maximal Yo-Yo intermittent recovery ice hockey tests, level 1 (Yo-Yo IR1-IHSUB and Yo-Yo IR1-IHMAX), the 5-10-5 pro-agility test, and a straight-line sprint test. Elite players were heavier (85.7 ± 8.1 vs. 80.8 ± 10.0 kg, p ≤ 0.05) and had a higher skeletal muscle mass (41.9 ± 3.9 vs. 38.8 ± 4.7 kg, p ≤ 0.05) than subelite players. Moreover, elite players elicited a superior CMJ (50.1 ± 6.1 vs. 44.9 ± 5.4 cm, p ≤ 0.05), agility (4.76 ± 0.17 vs. 4.96 ± 0.22 seconds, p ≤ 0.05), and sprint (4.49 ± 0.16 vs. 4.71 ± 0.19 seconds, p ≤ 0.05) performance. Finally, elite players outperformed subelite players in Yo-Yo IR1-IHSUB (79.7 ± 6.8 vs. 88.0 ± 5.4% HRmax, p ≤ 0.05) and Yo-Yo IR1-IHMAX tests (2,434 ± 414 vs. 1,850 ± 499 m, p ≤ 0.05). Top elite teams performed. 1.1 and 7% better than bottom elite teams on the agility and CMJ test (p ≤ 0.05), whereas differences approached significance for sprint (p = 0.08) and Yo-Yo IR1-IHMAX (p = 0.08) performance in favor of top-tier teams. No differences were observed between forwards and defensemen. In conclusion, elite-level ice hockey requires a high level of fitness in terms of muscle mass and explosive strength, as well as a well-developed high-intensity intermittent exercise capacity. In addition, these demands seem to apply for both forwards and defensemen.

Effects of a lighter, smaller football on acute match injuries in adolescent female football: a pilot cluster-randomized controlled trial.

BACKGROUND: The high injury incidence during match-play in female adolescent football is a major concern. In football, males and females play matches with the same football size. No studies have investigated the effect of football size on injury incidence in female adolescent football. Thus, the aim of the present study was to investigate the effects of introducing a lighter, smaller football on the injury pattern in female adolescent football. METHODS: We conducted a pilot cluster randomized controlled trial including 26 football teams representing 346 adolescent female football players (age 15-18 years). The teams were randomized to a new lighter, smaller football (INT, N.=12 teams) or a traditional FIFA size 5 football (CON, N.=14 teams) during a full match-season. Acute time-loss injuries and football-exposure during match-play were reported weekly by text-message questions and verified subsequently by telephone interview. RESULTS: In total, 46 acute time-loss injuries were registered (5 severe injuries), yielding an incidence rate of 15.2 injuries per 1000 hours of match-play (95% CI: 8.5-27.2) in INT and 18.6 injuries per 1000 hours of match-play (95% CI: 14.0-24.8) in CON. The estimated 22% greater injury incidence rate risk (IRR: 1.22 [95% CI: 0.64-2.35]) in the CON group was not significant. With an IRR of 1.22, a future RCT main study would need to observe 793 acute time-loss injuries during match-play, in order to have a power of 80%. CONCLUSIONS: A large-scaled RCT is required to definitively test for beneficial or harmful effects of a lighter, smaller football in adolescent female football.

Detection of Spatiotemporal Asymmetry in Pro Level Soccer Players.

Knudsen, NS and Andersen, TB. Detection of spatiotemporal asymmetry in pro level soccer players. J Strength Cond Res 32(3): 798-804, 2018-Several papers have focused on change of direction (COD) asymmetry investigated through standardized tests, and used this information to provide some spatiotemporal insight during games. The aim of this study was to investigate asymmetry in the reachable areas of the players through actual position data from soccer games. Sixteen professional players from the Danish Superliga participated in this study, but 5 were excluded because of lack of participation throughout the investigated games. The reachable areas of the players were investigated at varying sprint velocities (1-7 m·s) and within varying time intervals (0.5-4 seconds). The analysis found 7 players having spatiotemporal asymmetries in their reachable areas (0.5-3%) and shift of center of reachable area (4-29 cm). Four players (LB, RB, DM, and CF) had spatiotemporal asymmetries that could be attributed to COD and thus physiological asymmetries, whereas 3 players (LCB, LW, and RW) had spatiotemporal asymmetries that might be caused by their position or by use of tactic. This type of asymmetry was named a tactical spatiotemporal asymmetry. Coaches with knowledge about spatiotemporal asymmetries can use these actively in their tactical approach using the players' asymmetries in synergy, using opponents' asymmetries or improving the existing postgame spatiotemporal analyzing tools.

Position-Specific Acceleration and Deceleration Profiles in Elite Youth and Senior Soccer Players.

Vigh-Larsen, JF, Dalgas, U, and Andersen, TB. Position-specific acceleration and deceleration profiles in elite youth and senior soccer players. J Strength Cond Res 32(4): 1114-1122, 2018-The purpose of the study was to characterize and compare the position-specific activity profiles of young and senior elite soccer players with special emphasis put on accelerations and decelerations. Eight professional senior matches were tracked using the ZXY tracking system and analyzed for the number of accelerations and decelerations and running distances within different speed zones. Likewise, 4 U19 and 5 U17 matches were analyzed for comparison between youth and senior players. In senior players, the total distance (TD) was 10,776 ± 107 m with 668 ± 28 and 143 ± 10 m being high-intensity running (HIR) and sprinting, respectively. Number of accelerations and decelerations were 81 ± 2 and 84 ± 3, respectively, with central defenders performing the lowest and wide players the highest number. Declines were found between first and second halves for accelerations and decelerations (11 ± 3%), HIR (6 ± 4%), and TD (5 ± 1%), whereas sprinting distance did not differ. U19 players performed a higher number of accelerations, decelerations, and TD compared with senior players. In conclusion, differences in the number and distribution of accelerations and decelerations appeared between player positions, which is of importance when monitoring training and match loads and when prescribing specific training exercises. Furthermore, youth players performed as much high-intensity activities as senior players, indicating that this is not a discriminating physiological parameter between these players.

Technical Actions, Heart Rate, and Locomotor Activity in 7v7 and 8v8 Games for Female Youth Soccer Players.

Ørntoft, C, Larsen, MN, Andersen, TB, Rasmussen, LS, Póvoas, SCA, Randers, MB, and Krustrup, P. Technical actions, heart rate, and locomotor activity in 7v7 and 8v8 games for female youth soccer players. J Strength Cond Res 30(12): 3298-3303, 2016-The purpose of this study was to evaluate technical performance, heart rate (HR), and activity profile in 7v7 and 8v8 soccer games for 9- to 10-year-old girls (U11). A total of 24 female youth players participated in the study, all playing 20-minute 7v7 and 8v8 games with 160 and 223 m per player, respectively. Technical actions, HR, and activity profile were measured during the games using video filming, HR monitors, and 5-Hz Global positioning system (GPS) units. The number of technical actions was higher in 7v7 than in 8v8 games (34 ± 19 vs. 28 ± 14; p = 0.03; d = 0.37), as was the number of successful actions (25 ± 16 vs. 20 ± 12; p = 0.01; d = 0.35), with no difference in success rate for technical actions (70 ± 13 vs. 69 ± 14%; p = 0.63; d = 0.07). No differences were found between 7v7 and 8v8 in total distance covered (1,574 ± 251 and 1,622 ± 281 m; p = 0.66; d = 0.18), peak speed (19.5 ± 2.6 and 20.7 ± 1.5 km·h; p = 0.16; d = 0.56), mean HR values (85 ± 5 and 86 ± 6%HRpeak; p = 0.85; d = 0.18), and time of >90% HRpeak (37 ± 16 and 35 ± 14% of playing time; p = 0.70; d = 0.13). Distance covered at the highest running speeds of >16 km·h was lower in 7v7 than in 8v8 games (34 ± 24 vs. 63 ± 34 m; p = 0.018; d = 0.98), as was the number of entries into this speed zone (8 ± 5 vs. 13 ± 7; p = 0.006; d = 0.82). In conclusion, more technical actions and successful actions were observed in 7v7 than in 8v8 games, but players covered more ground with high-speed running in 8v8 games. This study also revealed that HR values were high in both game formats for U11 adolescent female players, with no difference between formats.

Kicking velocity and physical, technical, tactical match performance for U18 female football players--effect of a new ball.

We investigated kicking velocity and physical, technical, and tactical match performance for under-18 (U18) female football players and evaluated the effect of using a newly developed lighter smaller ball. Ten regional league teams participated. Maximal ball velocity was 4±1% higher when kicking the new ball (NB) compared with the standard ball (SB) in a laboratory testing situation (23.2±0.4 vs. 22.4±0.3 ms(-1); p<.05). Mean HR was similar during games with NB and SB (169±2 vs. 170±2 bmin(-1); p>.05), but lower-limb muscular RPE was lower with NB (4.2±0.4 vs. 5.2±0.3; p<.05). The number of activity changes (1387±76 vs. 1401±55), total distance covered (9.09±0.25 vs. 9.11±0.25 km) and high-intensity running (1.04±0.08 vs. 1.11±0.07 km) were not different between NB and SB (p>.05). High-intensity running decreased (p<.05) from 0-20 to 60-80 min with NB (34%) and SB (37%). The number and success rate of long and short passes did not differ between NB and SB (p>.05). In conclusion, physiological demands were high in youth female football games, and decrements in running performance occurred towards the end of games. The players kicked faster and reported lower muscular exertion during games played with a lighter smaller ball, but locomotor activities, heart rate and overall technical-tactical game performance remained unaffected.

Power monitoring in dielectric-loaded surface plasmon-polariton waveguides.

We report on propagating mode power monitoring in dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) by measuring the resistance of gold stripes supporting the DLSPPW mode propagation. Inevitable absorption of the DLSPPW mode in metal causes an increase in the stripe temperature and, thereby, in its resistance whose variations are monitored with an external Wheatstone bridge being accurately balanced in the absence of radiation in a waveguide. The investigated waveguide configuration consists of a 1-µm-thick and 10-µm-wide polymer ridges tapered laterally to a 1-µm-wide ridge placed on a 50-nm-thin and 4-µm-wide gold stripe, all supported by a magnesium fluoride substrate. Using single-mode polarization-maintaining fiber for in- and out-coupling of radiation, DLSPPW mode power monitoring at telecom wavelengths is realized with the responsivities of up to ~1.8 µV/µW (showing weak wavelength dependence) being evaluated for a bias voltage of 1 V.

Fiber-pigtailed temperature sensors based on dielectric-loaded plasmonic waveguide-ring resonators.

We demonstrate optical fiber-pigtailed temperature sensors based on dielectric-loaded surface plasmon-polariton waveguide-ring resonators (DLSPP-WRRs), whose transmission depends on the ambient temperature. The DLSPP-WRR-based temperature sensors represent polymer ridge waveguides (~1×1 µm(2) in cross section) forming 5-µm-radius rings coupled to straight waveguides fabricated by UV-lithography on a 50-nm-thick gold layer atop a 2.3-µm-thick CYTOP layer covering a Si wafer. A broadband light source is used to characterize the DLSPP-WRR wavelength-dependent transmission in the range of 1480-1600 nm and to select the DLSPP-WRR component for temperature sensing. In- and out-coupling single-mode optical fibers are then glued to the corresponding access (photonic) waveguides made of 10-µm-wide polymer ridges. The sample is heated from 21°C to 46 °C resulting in the transmission change of ~0.7 dB at the operation wavelength of ~1510 nm. The minimum detectable temperature change is estimated to be ~5.1∙10(-3) °C for the bandwidth of 1 Hz when using standard commercial optical detectors.

Compact on-chip temperature sensors based on dielectric-loaded plasmonic waveguide-ring resonators.

The application of a waveguide-ring resonator based on dielectric-loaded surface plasmon-polariton waveguides as a temperature sensor is demonstrated in this paper and the influence of temperature change to the transmission through the waveguide-ring resonator system is comprehensively analyzed. The results show that the roundtrip phase change in the ring resonator due to the temperature change is the major reason for the transmission variation. The performance of the temperature sensor is also discussed and it is shown that for a waveguide-ring resonator with the resonator radius around 5 µm and waveguide-ring gap of 500 nm which gives a footprint around 140 µm(2), the temperature sensitivity at the order of 10(-2) K can be achieved with the input power of 100 µW within the measurement sensitivity limit of a practical optical detector.

RNA aptamers as conformational probes and regulatory agents for plasminogen activator inhibitor-1.

The hallmark of serpins is the ability to undergo the so-called "stressed-to-relaxed" switch during which the surface-exposed reactive center loop (RCL) becomes incorporated as strand 4 in central beta-sheet A. RCL insertion drives not only the inhibitory reaction of serpins with their target serine proteases but also the conversion to the inactive latent state. RCL insertion is coupled to conformational changes in the flexible joint region flanking beta-sheet A. One interesting serpin is plasminogen activator inhibitor-1 (PAI-1), a fast and specific inhibitor of the serine proteases tissue-type and urokinase-type plasminogen activator. Via its flexible joints' region, native PAI-1 binds vitronectin and relaxed, protease-complexed PAI-1 certain endocytosis receptors. From a library of 35-nucleotides long 2'-fluoropyrimidine-containing RNA oligonucleotides, we have isolated two aptamers binding PAI-1 by the flexible joint region with low nanomolar K(D) values. One of the aptamers exhibited measurable binding to native PAI-1 only, while the other also bound relaxed PAI-1. While none of the aptamers inhibited the antiproteolytic effect of PAI-1, both aptamers inhibited vitronectin binding and the relaxed PAI-1-binding aptamer also endocytosis receptor binding. The aptamer binding exclusively to native PAI-1 increased the half-life for the latency transition to more than 6 h, manyfold more than vitronectin. Contact with Lys124 in the flexible joint region was critical for strong inhibition of the latency transition and the lack of binding to relaxed PAI-1. We conclude that aptamers yield important information about the serpin conformational switch and, because they can compete with high-affinity protein-protein interactions, may provide leads for pharmacological intervention.

Thermo-optic control of dielectric-loaded plasmonic waveguide components.

We report preliminary results on the development of compact (length < 100 microm) fiber-coupled dielectric-loaded plasmonic waveguide components, including Mach-Zehnder interferometers (MZIs), waveguide-ring resonators (WRRs) and directional couplers (DCs), whose operation at telecom wavelengths is controlled via the thermo-optic effect by electrically heating the gold stripes of dielectric-loaded plasmonic waveguides. Strong output modulation (> 20%) is demonstrated with MZI- and WRR-based components, and efficient (approximately 30%) rerouting is achieved with DC switches.

Anatomy and biomechanics of the back muscles in the lumbar spine with reference to biomechanical modeling.

STUDY DESIGN: This article describes the development of a musculoskeletal model of the human lumbar spine with focus on back muscles. It includes data from literature in a structured form. OBJECTIVE: To review the anatomy and biomechanics of the back muscles related to the lumbar spine with relevance for biomechanical modeling. SUMMARY OF BACKGROUND DATA: To reduce complexity, muscle units have been incorporated in an abridged manner, reducing their actions more or less to a single force equivalent. In early models of the lumbar spine, this may have been a necessary step to reduce complexity and, thereby, calculation time. The muscles of the spine are well described in the literature, but mainly qualitatively. Most of the literature provides a description of the structures without precise data of fiber length, muscle length, cross-sectional areas, moment arms, forces, etc. The predicted output of musculoskeletal models is very much dependent on the input parameters. The information needed to improve models consists of better approximations of the attachments to the vertebrae, and more precise data. METHOD: Review of literature. RESULTS: The predicted output of musculoskeletal models is very much dependent on the input parameters. Moderate changes in the assumed muscle line-of-action (i.e., moment arm) could substantially alter the magnitudes of predicted muscle and spinal forces, while the choice of optimization formulation is less sensitive. CONCLUSIONS: Input parameters, moment arms, as well as physiologic cross-sectional areas have a profound effect on the predicted muscle forces. Therefore, it is important to choose the values for moment arm and physiologic cross-sectional area carefully because they are essential input parameters to biomechanical models.