Y.T. Zhang

The Effect of Music on Hypertensive Patients

The aim of this study is to examine if, and to what extent, daily listening to a certain type of music can help hypertensive patients lower their blood pressure (BP). Experiments were conducted at an elderly home. Thirty subjects aged 63-93 years participated in the study and were randomly assigned into either a music group (n=15) or a control group (n=15). There were no significant differences between the two groups in initial BP values, age, gender, or medication status. Subjects in the music group listened to selected music, 25 min every day for 4 weeks. BP was measured twice a week by a registered nurse with a sphygmomanometer during the 4-week study period and after the completion of the study. Four subjects dropped from the experiment due to a change of medical conditions or to personal reasons. After 4 weeks, the average decrease for the music group (n=12) in systolic BP (SBP) and diastolic BP (DBP) was 11.8 mmHg (/>=0.008) and 4.7 mmHg (/>=0.218), respectively, whereas there was no significant changes in SBP or DBP for the control group (n=14). The results suggest that listening to a certain type of music serves to reduce high SBP and therefore music therapy may be an alterative for hypertension treatment.

Spectral analysis of pulse transit time variability and its coherence with other cardiovascular variabilities.

Pulse transit time (PTT) has been reported correlated with heart rate (HR) and blood pressure (BP), however, the results are not consistent in different investigations. Towards a better understanding of the underlying mechanisms of the PTT changes, this study compares the power spectrum density of the variability in PTT with that in HR and BP under rest and post-exercise physiological conditions. Coherence function is also examined to quantify the strength of coupling between paired variabilities. The results show that the pulse transit time variability (PTTV) has significant coherence (>0.5) with heart rate variability (HRV) and blood pressure variability (BPV) under all physiological conditions at high frequency (HF). However, at the low frequency (LF) band, the coherence reduced to insignificance immediately after the exercise (minutes after exercise) and then return back to significant level 9 minutes after the exercise. The results show that PTTV is strongly coupled with HRV and BPV at the HF, indicating that the parasympathetic modulation could be the main cause of PTTV. The unstable coupling relationship of PTTV with BPV at LF should raise caution in the beat-to-beat BP estimation by PTT in the dynamic situation

A biometric method to secure telemedicine systems

Security and privacy are among the most crucial issues for data transmission in telemedicine systems. This paper proposes a solution for securing wireless data transmission in telemedicine systems, i.e. within a body sensor network (BSN), between the BSN and server as well as between the server and professionals who have assess to the server. A unique feature of this solution is the generation of random keys by physiological data (i.e. a biometric approach) for securing communication at all 3 levels. In the performance analysis, inter-pulse interval of photoplethysmogram is used as an example to generate these biometric keys to protect wireless data transmission. The results of statistical analysis and computational complexity suggest that this type of key is random enough to make telemedicine systems resistant to attacks.

Vertebral blood perfusion reduction associated with vertebral bone mineral density reduction: A dynamic contrast‐enhanced MRI study in a rat orchiectomy model

To investigate the relationship between vertebral blood perfusion and vertebral bone mineral density (BMD) in a rat orchiectomy (ORX) model.

A novel parameter from PPG dicrotic notch for estimation of systolic blood pressure using pulse transit time

This paper proposes a new calibration parameter from the dicrotic notch of photoplethysmography (PPG) waveform for systolic blood pressure (SBP) estimation using pulse transit time (PTT). An experiment including exercise was conducted on twelve subjects. The results show that estimation with PTT and a new parameter, i.e. the Relative Amplitude of Secondary peak (RAS), can predict SBP within 1.7 plusmn 6.8 mmHg of the reference for all the subjects before and after exercise (including within 5 minutes and 20-40 minutes after exercise). The underestimated bias after exercise if PTT was used alone can be largely reduced when RAS is introduced. The preliminary analysis indicates that RAS is a promising parameter for calibrating the PTT-based approach for cuffless BP estimation.

A novel method for the contactless and continuous measurement of arterial blood pressure on a sleeping bed

Nighttime blood pressure (BP) is found to best predict the 5-year risk of cardiovascular death in comparison to daytime BP, BP measured over a 24-hour period and clinical BP. In view of this, a novel contactless system has been developed on a sleeping bed for the cuffless and continuous estimation of BP at night. Experiments were conducted on 11 subjects to evaluate the contactless system, particularly its performance compared to a contact system. The results of this study showed that the accuracy of the contactless system to estimate BP by a cuffless approach is comparable to that of the contact system when measured at the same posture. More studies have to be conducted in order to understand the difference of the cuffless BP estimation approach when measuring at supine and sitting postures.

A biometrics based security solution for encryption and authentication in tele-healthcare systems

Security and privacy are among the most crucial issues for data transmission in tele-healthcare applications. The paper proposes a biometrics based solution, combining encryption and authentication for wireless communication within a body sensor network (BSN), as well as between a BSN and a remote server (RS) of a tele-healthcare system. The method aims to use static and dynamic biometric traits to generate authentication and encryption keys respectively. Keys of 64 and 128 bits were generated from electrocardiogram and photoplethysmogram of 9 subjects and fingerprint images of 20 subjects. The entropy of the keys ranged from 0.662 to 1 and the hamming distances between them were all non-zero. The results of this study found that random and distinctive keys can be generated by a biometric approach for encrypting and authenticating data in tele-healthcare systems.

Using the Changes in Hydrostatic Pressure and Pulse Transit Time to Measure Arterial Blood Pressure

The pulse transit time (PTT)-based method has been proposed as a noninvasive and cuffless alternative for monitoring blood pressure (BP). Yet, a major challenge of the technology is to overcome the requirement of individual calibration. In this study, we aim to explore the possibility of using the changes in hydrostatic pressure and PTT for estimating BP without a calibrating procedure. Eight subjects (aged 35plusmn15 years) participated in the study and their PTT were recorded during an arm movement exercise. The results of the study found that PTT increases correspondingly with the height of the arm the subjects raised. Moreover, the calculated changes in PTT agree with that derived from the theoretical model using parameter values which were previously reported in literature. To conclude, the cuffless approach presented in this paper is potentially useful for the estimation of arterial BP.

Gender difference of serum angiotensin- converting enzyme (ACE) activity in DD genotype of ACE insertion/deletion polymorphism in elderly Chinese

Introduction: In this study we investigated the gender difference of serum angiotensin-converting enzyme (ACE) activity in a population of Hong Kong-dwelling elderly Chinese. Materials and methods: A total of 1767 (843 male, 924 female) Hong Kong-dwelling elderly Chinese were recruited. ACE I/D genotypes were identified by polymerase chain reaction amplification and serum ACE activity was determined using a commercially available kinetic kit. ACE I/D genotype distribution was compared by chi-square test, the correlation between ACE I/D polymorphism and serum ACE activity was analysed by ANOVA test and gender difference of serum ACE activity of different genotypes was compared by independent sample t-test. Results: No statistically significant difference of genotype distribution between male and female subjects was found. Serum ACE activity was significantly correlated with ACE genotype. Overall, there was no gender difference of serum ACE activity; however, when sub-grouping the subjects by ACE I/D genotype, male subjects with DD genotype had higher serum ACE activity than female subjects with DD genotype. Conclusions: No significant gender difference of genotype distribution was found in elderly Chinese. Serum ACE activity was significantly correlated with ACE I/D polymorphism in elderly Chinese. Male subjects with DD genotype had higher serum ACE activity than female subjects with DD genotype.

Proximal femur bone marrow blood perfusion indices are reduced in hypertensive rats: a dynamic contrast-enhanced MRI study.

To investigate the differences in proximal femoral bone marrow blood perfusion indices between hypertensive and normotensive rats using perfusion magnetic resonance imaging (MRI).