Development of a novel index to characterise arterial dynamics using ultrasound imaging

Abdominal aortic aneurysms (AAA) are associated with systemic inflammation and endothelial dysfunction. We previously reported flow mediated dilatation (FMD) of the brachial artery as a predictor of AAA growth. We hence hypothesised that other physical characteristics of the brachial artery correlate with AAA growth. Using a prospectively cohort of AAA patients, we devised a ‘brachial artery relaxation index’ (BARI) and examined its role as a biomarker for AAA growth. However, no correlation between BARI and future aneurysm growth was observed (p = 0.45). Therefore, our investigations did not substantiate the hypothesis that other physical characteristics of the brachial artery predicts AAA growth.

Neuromechanical Assessment of Activated vs. Resting Leg Rigidity Using the Pendulum Test Is Associated With a Fall History in People With Parkinson’s Disease

Leg rigidity is associated with frequent falls in people with Parkinson’s disease (PD), suggesting a potential role in functional balance and gait impairments. Changes in the neural state due to secondary tasks, e.g., activation maneuvers, can exacerbate (or “activate”) rigidity, possibly increasing the risk of falls. However, the subjective interpretation and coarse classification of the standard clinical rigidity scale has prohibited the systematic, objective assessment of resting and activated leg rigidity. The pendulum test is an objective diagnostic method that we hypothesized would be sensitive enough to characterize resting and activated leg rigidity. We recorded kinematic data and electromyographic signals from rectus femoris and biceps femoris during the pendulum test in 15 individuals with PD, spanning a range of leg rigidity severity. From the recorded data of leg swing kinematics, we measured biomechanical outcomes including first swing excursion, first extension peak, number and duration of the oscillations, resting angle, relaxation index, maximum and minimum angular velocity. We examined associations between biomechanical outcomes and clinical leg rigidity score. We evaluated the effect of increasing rigidity through activation maneuvers on biomechanical outcomes. Finally, we assessed whether either biomechanical outcomes or changes in outcomes with activation were associated with a fall history. Our results suggest that the biomechanical assessment of the pendulum test can objectively quantify parkinsonian leg rigidity. We found that the presence of high rigidity during clinical exam significantly impacted biomechanical outcomes, i.e., first extension peak, number of oscillations, relaxation index, and maximum angular velocity. No differences in the effect of activation maneuvers between groups with clinically assessed low rigidity were observed, suggesting that activated rigidity may be independent of resting rigidity and should be scored as independent variables. Moreover, we found that fall history was more common among people whose rigidity was increased with a secondary task, as measured by biomechanical outcomes. We conclude that different mechanisms contributing to resting and activated rigidity may play an important yet unexplored functional role in balance impairments. The pendulum test may contribute to a better understanding of fundamental mechanisms underlying motor symptoms in PD, evaluating the efficacy of treatments, and predicting the risk of falls.

Development of a Novel Index to Characterise Arterial Dynamics Using Ultrasound Imaging

Abdominal aortic aneurysms (AAA) are associated with systemic inflammation and endothelial dysfunction. We previously reported flow mediated dilatation (FMD) of the brachial artery as a predictor of AAA growth. We hence hypothesised that other physical characteristics of the brachial artery correlate with AAA growth. Using a prospectively cohort of AAA patients, we devised a ‘brachial artery relaxation index’ (BARI) and examined its role as a biomarker for AAA growth. However, no correlation between BARI and future aneurysm growth was observed (p=0.5). Therefore, our investigations did not substantiate the hypothesis that other physical characteristics of the brachial artery predicts AAA growth.

Biomechanical outcomes of the pendulum test characterize individual differences in activated versus resting leg rigidity in people with Parkinson's disease

Leg rigidity is associated with frequent falls in people with Parkinson's disease (PD), suggesting a potential role in functional balance and gait impairments. Changes in neural state due to secondary tasks, e.g. activation maneuvers, can exacerbate (or 'activate') rigidity, possibly increasing the risk of falls. However, the subjective interpretation and coarse classification of the standard clinical rigidity scale has prohibited the systematic, objective assessment of resting and activated leg rigidity. The pendulum test is an objective diagnostic method that we hypothesized would be sensitive enough to characterize resting and activated leg rigidity. We recorded kinematic data during the pendulum test in 15 individuals with PD, spanning a range of leg rigidity severity (slight to severe). From the recorded data of leg swing kinematics we measured biomechanical outcomes including first swing excursion, first extension peak, number and duration of the oscillations, resting angle, relaxation index, maximum and minimum angular velocity. We examined associations between biomechanical outcomes and clinical leg rigidity score. We evaluated the effect of increasing rigidity through activation maneuvers on biomechanical outcomes. Finally, we assessed whether either biomechanical outcomes or changes in outcomes with activation were associated with fall history. Our results suggest that the biomechanical assessment of the pendulum test can objectively quantify leg rigidity among people with PD. We found that the presence of marked rigidity during clinical exam significantly impacted biomechanical outcomes, i.e. first extension peak, number of oscillations, relaxation index and maximum angular velocity. No differences in the effect of activation maneuvers between groups with clinically assessed moderate and marked rigidity were observed, suggesting that activated rigidity may be independent of resting rigidity and should be scored as independent variables. Moreover, we found that fall history was more common among people whose rigidity was increased with a secondary task, as measured by biomechanical outcomes. We conclude that different mechanisms contributing to resting and activated rigidity may play an important yet unexplored functional role in balance impairments. The pendulum test may contribute to a better understanding of fundamental mechanisms underlying motor symptoms in PD, evaluating the efficacy of treatments, and predicting the risk of falls.

Changes in Roughness and Mechanical Properties of Invisalign® Appliances after One- and Two-Weeks Use

The aim of this study was to estimate the possible changes of surface roughness and the mechanical properties of Invisalign® appliances over one- and two-week of service. Forty appliances with attachments were retrieved after the end of orthodontic treatment from different patients. Half of them had been used for one week (1W), and the rest for two weeks (2W). Ten unused Invisalign® appliances were used as the control (CON). An equal number of teeth possessing attachments were cut of aligners deriving from all groups (1W, 2W, and CON), and the Sa, Sq, Sz, Sc, and Sv roughness parameters of the internal surface of the aligner attachment area and the opposite lingual side (which was in contact to enamel) were determined by optical profilometry. Then, ten first molars originating from all groups were embedded in acrylic resin, and were ground and polished. Instrumented indentation testing (IIT) was performed in order to determine the Martens hardness (HM), indentation modulus (EIT), and relaxation index (RIT), according to ISO 14577-2002. The produced data were statistically processed by one- or two-way analysis of variance (ANOVA) and multiple comparison post-hoc tests (a = 0.05). Both the surface roughness and mechanical properties of the retrieved groups (1W and 2W) showed statistically significant differences compared with CON, but without statistically significant differences between each other. The roughness variables of the as-received material were shown to be reduced after intraoral service demonstrating a wear effect. Ageing has a detrimental effect on the surface roughness and mechanical properties of Invisalign® appliances, although this effect is restricted to the first week of clinical usage.

Effects of Symbol Component on the Identifying of Graphic Symbols from EEG for Young Children with and without Developmental Delays

Using Augmentative and Alternative Communication (AAC) to improve the communication skills of children with disabilities is generally supported by both domestic and foreign scholars. Graphic symbols that represent individual words or phrases are often used in conjunction with AAC; however, research on the reading and identifying of AAC graphic symbols is scant. Therefore, this study used electroencephalogram (EEG) to investigate the success rates of identifying AAC graphic symbols and brainwave changes of young children with and without developmental delays. The results revealed that the number of symbol components affected participants’ success rates of identifying AAC graphic symbols. The EEG Attention Index between the children with and without developmental delays varied during the test. By contrast, the EEG Relaxation Index exhibited no difference between the children with and without developmental delays. When the participants viewed the single-component animations, the children without developmental delays had a significantly higher Relaxation Index than those with developmental delays did. According to cognitive load theory, the children with developmental delays and low cognitive capacities may feel stressed.

Abstract 2910: Echocardiographic Indices For Diastolic Function Correlate to With The Collagen Content From Endomyocardial Biopsies In Patients With Heart Failure And Normal Ejection Fraction

Background: Morphologic charactheristics of the ventricle can influence the LV stiffness and therefore its diastolic function. We correlated diastolic parameters with collagen content from the endomyocardial biopsies (EMBs) in the patients with heart failure and normal EF. Method: We investigated 24 patients (51 ±10 years) with normal EF (65 ±8) and heart failure symptoms, whose endomyocardial biopsies (EMBs) were previously taken. Patients with coronary artery disease, valvular disease or atrial fibrillation were excluded. Total collagen content was determined using Sirius red staining. Collagen subtypes I and III were determined by standard immunohistochemistry methods in 19 patients. Assessment of diastolic function was performed by conventional Doppler (E/A, DT, IVRT), tissue Doppler measurements (E’/A’) and LV filling index E/E’. Results: Tissue Doppler parameters E’/A’ and E/E’ correlated strong with collagen content (r=-0.52, p=0.028 and r=0.50, p=0.040 respectively) and with collagen subtype I (r=-0.68, p=0.015 and r=0.66, p=0.018), whereas E/A (r= -0.34, p=0.078 and r=-0.28, p=0.268) and DT (r=0.22, p=0.093 and r=0.21, p=0.211) did not reach a statistical significance. Relaxation index IVRT correlated with collagen subtype I (r=0.62, p=0.014). Conclusion: Of all parameters tissue Doppler and LV filling index E/E’ correlated best with increased collagen content of endomyocardial biopsies in patients with heart failure and normal EF indicating induced cardiac remodelling process in those patients.