Ambulatory stress monitoring with a wearable bluetooth electrocardiographic device.

We tried to monitor stress by using a wearable one channel ECG device that can send ECG signals through Bluetooth wireless communication. Noxious physical and mental arithmetic stress was given three times repeatedly to healthy adults, and cortisol and catecholamines were measured serially from peripheral blood. At the same time, time domain and frequency domain parameters of heart rate variability (HRV) were calculated by taking precordial electrocardiogram. The intensity of correlation between subjective visual analogue scale (VAS) and catecholamine, cortisol, and HRV parameters according to stress was analyzed by using concordance correlation coefficients. The HRV triangular index and LF/HF ratio had high concordance correlation with the degree of stress in the physical stress model. In mental arithmetic stress model, the HRV triangular index and LF/HF ratio had weak concordance correlation with the degree of stress, and it had lower predictability than epinephrine. In both models, cortisol had some correlation with catecholamine, but it had little correlation with HRV parameters. HRV parameters using wearable one channel ECG device can be useful in predicting acute stress and also in many other areas.

Performance study of the wearable one-lead wireless electrocardiographic monitoring system.

This study attempts to compare and assess the performance of a wearable electrocardiogram (ECG) using a sensing fabric electrode and a Bluetooth network with a conventional ECG. A one-lead ECG examination was performed using Bioshirt and an iWorx 214 while walking or running at 3, 6, and 9 km per hour. A correlation coefficient of a heart rate variability (HRV) between these two devices was higher than 0.96 and power spectral density of HRV measured also showed an excellent agreement. Thus, both of these two ECG devices showed similar detection capability for R peaks. The measured values for wave duration and intervals of both devices concur with each other. The intensity of noise is controversial. The ECG device using a sensing fabric electrode and a wireless network showed an ECG signal detection and transmission capability similar to that of a conventional ECG device.

The effect of rod domain A148V mutation of neurofilament light chain on filament formation.

Neurofilaments (NFs) are neuronal intermediate filaments composed of light (NF-L), middle (NF-M), and heavy (NF-H) subunits. NF-L self-assembles into a "core" filament with which NF-M or NF-H co-assembles to form the neuronal intermediate filament. Recent reports show that point mutations of the NF-L gene result in Charcot-Marie-Tooth disease (CMT). However, the most recently described rod domain mutant of human NF-L (A148V) has not been characterized in cellular level. We cloned human NF-L and used it to engineer the A148V. In phenotypic analysis using SW13 cells, A148V mutation completely abolished filament formation despite of presence of NF-M. Moreover, A148V mutation reduced the levels of in vitro self-assembly using GST-NF-L (H/R) fusion protein whereas control (A296T) mutant did not affect the filament formation. These results suggest that alanine at position 148 is essentially required for NF-L self-assembly leading to subsequent filament formation in neuronal cells.

Robust measurement of ocular torsion using iterative Lucas-Kanade.

We present a new method to measure ocular torsion using Lucas-Kanade method. After pixels of iris annulus around a pupil have been converted into Cartesian coordinates, 30 features on the iris was selected then the features were tracked using the iterative Lucas-Kanade algorithm to calculate torsional shift. The results show that a precision of the method is higher than those measured by a conventional cross-correlation and by a template matching method. The suggested method showed 0.03 degrees mean error with 0.15 degrees maximum error. Particularly, the method was robust to change of pupil size and misalignment of pupil location. Processing time was also fast enough to be implemented in a real-time system.

In vitro assay of neurofilament light chain self-assembly using truncated mutants.

Neurofilaments (NFs) are heteropolymers composed of light (NF-L), middle (NF-M), and heavy (NF-H) subunits, present in most neurons. NF-L polymerizes on its own to provide a scaffold on which regular NFs form via the cross-bridging of NF-M or NF-H. To clarify the mechanism of regulation of NF-L self-assembly, we developed an assay using truncated mutant NF-L fused to glutathione-S transferase (GST). Western immunoblotting data show that the GST-fused head-rod domains of NF-L are necessary and sufficient for detecting assembled NF-L. The levels of self-assembled NF-L subunits detected using GST fusion proteins were consistent with those detected by electron microscopy and turbidity assay. Our results collectively imply that GST-fused head-rod domains of NF-L are critical tools for analyzing NF-L self-assembly in vitro.

Development of pupillography using image processing.

PURPOSE: Pupillary examination is an important objective method to diagnose lesions of the anterior visual pathways. However, errors and faults may easily alter the interpretation and value of the test as it is highly dependent on the examiner's skills. Therefore, we tried to develop a pupillography which is independent of the examiner. METHODS: Hardware composed of a binocularly measuring instrument adapted for an infrared charge coupled device (CCD) was developed. Two arrays of infrared light emitting diodes (LED) were supplied in front of each of the subject's eyes. A microcontroller to modulate these LED was developed, as was software to save and analyze the pupil images. The hardware was able to deliver a light to either eye or to both eyes, and to change the time, frequency, and intensity of the stimulus. The software automatically analyzed the pupil size and location by image processing. Pupil size was calculated continuously. After artifact elimination, the response amplitudes of the pupils were determined for the right and left pupils. RESULTS: Pupillary images of size 320 x 240, at 30 frames/second, were saved and processed to evaluate the change of the actual pupil size and the velocity of pupillary response. CONCLUSIONS: A pupillography to measure, save and analyze the pupillary response using image processing was developed. Further detailed clinical studies with a large number of patients will be required to validate this new method.

Effects of dehydroepiandrosterone on articular cartilage during the development of osteoarthritis.

OBJECTIVE: To investigate the in vivo effects of dehydroepiandrosterone (DHEA) on knee joints during the development of experimentally induced osteoarthritis (OA). METHODS: Twenty-two mature NZW rabbits underwent bilateral anterior cruciate ligament transection (ACLT) and received 0.3-ml intraarticular injections of DHEA (at a concentration of 100 microM in phosphate buffered saline) and control solution in the right and left knees, respectively, beginning 4 weeks after ACLT and continuing once weekly for 5 weeks. All animals were killed 9 weeks after surgery, and the knee joints were assessed by gross morphologic, histologic, histomorphometric, and biochemical methods. RESULTS: Gross morphologic inspection following India ink application showed that the right femoral condyles, which received DHEA, demonstrated less severe cartilage damage than did the contralateral condyles. The thickness, area, and roughness of the DHEA-treated femoral condyles provided evidence of a cartilage-protecting effect of DHEA following ACLT. These results were supported by gene expression analysis. Messenger RNA expression of a proinflammatory cytokine, interleukin-1beta, and catabolic enzymes, matrix metalloproteinases 1 and 3, was reduced in the cartilage of the DHEA-treated knee joints, and expression of tissue inhibitor of metalloproteinase 1 was increased. CONCLUSION: Results of the present study demonstrate a cartilage-protecting effect of DHEA during the development of OA following ACLT in a rabbit model.