CONFORMATION-SPECIFIC IR AND UV SPECTROSCOPY OF A SERIES OF SYNTHETIC FOLDAMERS: α/β3- AND β3- ALA DIPEPTIDES

With the development of designed foldamers that display biological activity and aid in drug delivery processes, there is an increasing interest in exploring the inherent conformational properties of model foldamers to understand better the subtle counter-balance of forces at play $\beta$-amino acids have one additional backbone carbon atom that extends the spacing between amide groups, thereby providing flexibility in construction of $\beta$- and $\alpha$/$\beta$- peptides, leading to secondary structures that either mimic or are complementary to those found in nature. Here we explore the conformational preferences of a series of $\beta$- and $\alpha$/$\beta$- dipeptides under jet-cooled conditions in the gas phase. The molecules are brought into the gas phase using laser desorption. Our studies include two capped $\alpha$/$\beta$ - dipeptides, Ac-L-Ala-$\beta^{3}$-(R)-hAla-NHBn and Ac-$\beta^{3}$-(R)-hAla-L-Ala-NHBn as structural isomers, and one capped pure $\beta^{3}$-dipeptide, Ac-(R)-hAla-$\beta^{3}$-(S)-hAla-NHBn . By incorporating an NHBn cap, a UV chromophore is present that can be used to record resonant two-photon ionization (R2PI) spectra. Conformation-specific infrared and ultraviolet spectra are then recorded using resonant ion-dip infrared (RIDIR) and IR-UV hole burning spectroscopies, respectively. With this set of peptides, we are able to probe the effect of a chirality switch at a single chiral center on inherent local conformational preferences. Following an exhaustive computational search of the conformational potential energy surface, low-lying minima are optimized and IR spectra calculated for comparison with the experimental RIDIR spectra provide conformational assignments. Lowest-energy conformers are observed for the $\alpha$/$\beta$-peptides and assigned to C7/C8 (C8/C7) hydrogen-bonded architectures, while for the pure $\beta^{3}$-peptide analog, only one conformer is observed experimentally and assigned to a C12 hydrogen-bonded architecture

CONFORMATION-SPECIFIC IR AND UV SPECTROSCOPY OF A MODEL SYNTHETIC FOLDAMER: β3-ALA TRIPEPTIDE

With the development of designed foldamers that that display biological activity and aid in drug delivery processes, there is an increasing interest in exploring the inherent conformational properties of model foldamers to understand better the subtle counter-balance of forces at play. $\beta$-amino acids have one additional backbone carbon atom that extends the spacing between amide groups, thereby providing a flexibility of construction, leading to secondary structures that either mimic or are complementary to those found in nature. Here we explore the secondary structures of foldamers in which the position of substitution of the methyl side chains of the Ala residues are switched from the $\beta$$^{2}$ to the $\beta$$^{3}$ position. In particular, we present data on a $\beta$$^{3}$-Ala tripeptide, Ac- $\beta$$^{3}$-Ala- $\beta$$^{3}$-Ala-$\beta$$^{3}$-Ala-NHBn under jet-cooled, isolated conditions. This talk will present conformation-specific IR and UV spectra using the techniques of resonant ion-dip infrared (RIDIR) spectroscopy and IR-UV holeburning, respectively. Following an exhaustive computational search of the conformational potential energy surface, low-lying minima are optimized and IR spectra calculated for comparison with the experimental RIDIR spectra. A single conformer is observed experimentally and assigned to a conformer with a C12/C8 hydrogen-bonded architecture that incorporates a 12-membered turn that is the $\beta$-peptide analog of a $\beta$-turn

EFFECTS OF EXERCISE ON ANKLE PROPRIOCEPTION DURING SIXTEEN WEEKS OF TRAINING AND EIGHT WEEKS OF DETRAINING IN OLDER ADULTS

This study evaluates the ankle proprioception in older adults. Sixty women (age 62.1±4.3yr) were randomly assigned to three groups to undergo a 16-week training (one group practice Tai Chi,one group practice brisk walking and one group reading) and 8-week detraining program. Proprioception of ankle plantarflexion (PF), dorsiflexion (DF) were measured, better proprioception is defined as being able to detect a smaller degree in joint angle. The results showed that degree PF and DF changes earlier and were smaller in TG than in BG in training; degree of PF and DF declined in all groups during the detraining, but TG exhibited a significant difference with pre-training data. So Tai Chi can more effectively improve and maintain ankle proprioception as well as prevent fall in old age. However, the extent of benefit depends on the regularity of training in older adults

THE POTENTIAL INJURY RISK OF BACKPACK WEIGHT ON POSTURE AND GROUND REACTION FORCES OF OBESE CHILDREN DURING STAIR DESCENT

This study investigated the effects of backpack weight on posture, gait pattern, and ground reaction forces for children with obesity in an attempt to define a safe backpack weight limit for them. A total of 16 obese (11.19±0.66 years of age) and 21 normal body weight (11.13±0.69 years of age) school boys were recruited. Two force plates and two video cameras were used. Multivariate analysis of variance with repeated measures was employed. Obese children showed increased trunk and head forward inclination angle, increased ground reaction force in the medial-lateral and anterior-posterior directions when compared to male children with a normal body weight. The changes were observed even with an empty backpack in comparison with normal body weight children and a 15% increase in backpack weight led to further instability and damage on their already strained bodies

EFFECTS OF RUNNING BIOMECHANICS ON THE OCCURRENCE OF ILIOTIBIAL SYNDROME IN MALE RUNNERS — A PROSPECTIVE STUDY

This study aimed to determine the gait characteristics that easily induce ITBS and explore the gait changes after the occurrence of ITBS. 30 healthy male runners participated in our study, 15 in ITBS and control group respectively. All participants underwent two gait trials, namely, before the first day of their routine running and after 8 weeks. After 8 weeks of running, the ITBS group exhibited greater peak anterior pelvic tilt and hip flexion angle than the control group. The ITBS group showed increased peak trunk inclination angle, whereas the control group demonstrated lower peak hip flexion and peak hip adduction than those at the beginning of running. Decreased peak hip flexion and peak hip adduction angle was a gait adjustment strategy that could be used to avoid ITBS occurrence. Excessive trunk posture and pelvic activity during running are also ITBS risk factors

ANALYSIS OF DYNAMIC STABILITY WHILE TEXTING DURING STAIR DESCENT

The purpose of this study was to explore the modifications in saggital and frontal dynamic stability during stair descent while texting to provide a database for guidelines of fall prevention. Participants (n=26; 13 male, 13 female) performed three stair descent trials under texting and No texting task conditions at self-selected speed, respectively. Synchronous kinematics and kinetics were collected by an eight-camera Vicon infrared motion capture system and two force platforms. A paired sample t-test was used to analyze the differences between two task conditions. With the interference of texting, anterior–posterior margin of stability (MOSap) increased in the initiation of double-support phase (DSP), while decreased in the initiation of single-support phase (SSP), medial–lateral MOS (MOSml) decreased in the initiation of SSP. Posterior instability was induced in the initiation of DSP. The initiation of DSP was the most unstable moment and should alert texters, particularly young adults, to potential risk of falling backward during stair descent

EFFECTS OF PNF INTERVENTION ON PAIN, JOINT PROPRIOCEPTION AND KNEE MOMENTS IN THE ELDERLY WITH KNEE OSTEOARTHRITIS DURING STAIR ASCENDING

In this study, we aimed to explore the effects of a 6-week proprioceptive neuromuscular facilitation (PNF) intervention on stair pain, joint proprioception, and external knee moment in the elderly patients with knee osteoarthritis (KOA) during stair ascending. A total of 27 elderly patients with KOA participated in our study. Fourteen of the patients were included in the PNF group, and 13 were included in the control group. The WOMAC measures for specific pain and joint motion sense measures were used, and gait test were performed at weeks 0 and 6. After a 6-week PNF intervention, the PNF group showed a decreased “using stairs” pain score, decreased difficulty with “climbing stairs” score, decreased joint kinesthesia threshold, increased knee flexion moment (KFM), and decreased knee adduction moment (KAM) during climbing stairs. We suggest the use of PNF intervention, which relieves joint pain, enhances muscles strength and proprioception recovery, increases KFM, and decreases KAM, in the treatment of KOA in elderly patients

DETRAINING EFFECTS OF TAI CHI ON STATIC BALANCE IN OLDER WOMEN

This study aimed to investigate the detraining effects of Tai Chi (TC) on balance ability in single leg stance (SLS). TC, brisk walking (BW), and control (C) groups completed a 16-week intervention and 8-week detraining program. Time and center of pressure trajectory in SLS was tested with pressure plate at baseline, 16th, 24th week. Primary outcome (Time) and secondary outcomes (Lng, Area, D-ap, D-ml) improved significantly at the 16th week in the TC and BW groups. Most outcomes increased significantly at the 24th week compared to the 16th week in the BW group. TC was effective to improve balance ability and maintaining intervention gains and is recommended as an appropriate exercise to prevent falls in the older adults

BIOMECHANICS AND INJURY RISK FACTORS DURING RACE WALKING

The purpose of this study is to describe the biomechanical characteristics during race walking and identify whether the race walking rules could cause potential injury risks. Fourteen elite race walkers participated in this study. Rs-scan plantar pressure plate and three digital cameras were used to collect data during race walking and normal walking. Paired t-tests were used to detect the differences. The results showed that during race walking, the peak pressures of the lateral heel and medial heel, the displacements of the center of pressure, ankle dorsiflexion, plantarflexion, knee extension, hip adduction, foot eversion, ankle angular velocity, and average horizontal velocity were significantly larger than those during normal walking. The greater heel peak pressure and more ankle eversion may be the injury risks caused by the rules of race walking

The RELIABILITY OF A NEW DEVICE FOR ASSESSING ANKLE JOINT PRORIOCEPTION IN HEALTHY ADULTS

The objective of this study is to evaluate the within-day and between-day reliability of a new device for assessing ankle joint prorioception. Eleven healthy adults, composed of seven males and four females, participated in the study. Each subject completed three sessions, two on the same day and the last one week later. In each session, three successful testing trials for ankle joint plantarflexion, dosiflexion, inversion, and eversion were performed. The mean values in one direction were calculated and analyzed. The within-day ICC values ranged from 0.808 to 0.973. The SEM for the device ranged from 0.118 ° to 0.448 °. The between-day ICC values ranged from 0.628 to 0.884. The SEM ranged from 0.287 °to 0.618 °. The measurements indicate good to excellent reliability of the device