Guanghao Zhang

A fast key generation method based on dynamic biometrics to secure wireless body sensor networks for p-health

Body sensor networks (BSNs) have emerged as a new technology for healthcare applications, but the security of communication in BSNs remains a formidable challenge yet to be resolved. The paper discusses the typical attacks faced by BSNs and proposes a fast biometric based approach to generate keys for ensuing confidentiality and authentication in BSN communications. The approach was tested on 900 segments of electrocardiogram. Each segment was 4 seconds long and used to generate a 128-bit key. The results of the study found that entropy of 96% of the keys were above 0.95 and 99% of the hamming distances calculated from any two keys were above 50 bits. Based on the randomness and distinctiveness of these keys, it is concluded that the fast biometric based approach has great potential to be used to secure communication in BSNs for health applications.

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.

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.

Compensation for injury potential by electrical stimulation after acute spinal cord injury in rat

Injury potential, a direct current potential difference between normal section and the site of injury, is a significant index of spinal cord injury. However, its importance has been ignored in the studies of spinal cord electrophysiology and electrical stimulation (ES). In this paper, compensation for injury potential is used as a criterion to adjust the intensity of stimulation. Injury potential is modulated to slightly larger than 0 mV for 15, 30 and 45 minutes immediately after injury by placing the anodes at the site of injury and the cathodes at the rostral and caudal section. Injury potentials of all rats were recorded for statistical analysis. Results show that the injury potentials acquired after ES are higher than those measured from rats without stimulation and much lower than the initial amplitude. It is also observed that the stimulating voltage to keep injury potential be 0 remain the same. This phenomenon suggests that repair of membrane might occur during the period of stimulation. It is also suggested that a constant voltage stimulation can be applied to compensate for injury potential.

Construction of modular novel bioartificial liver support system

A modular novel bioartificial liver support system was designed and constructed in order to simplify tedious operation of artificial liver treatment and to improve the applicability in the system. The design ideas, structure composition, system function, and etc, were described in detail. In this system, the variety of the therapy modes could be conveniently connected by the interface of modular structure. Industrial control computer was used as the main control platform, and physical of control parameters such as pressure, pump speed, dissolved oxygen, temperature, and etc, were transmitted into computer, then according to the instruction, process of the treatment was accomplished by the executing units implemented by main control system. Touch screen of human-computer interface was adopted, which made the system better operational and more comfortable. The system has passed the spot function test, and all indexes can meet requirements for the clinical treatment requested. It has the character such as modular design, systematic distribution, building-block structure, and etc, which supports a great novel operation platform for artificial therapy.

Effect of DSPE-PEG on compound action potential, injury potential and ion concentration following compression in ex vivo spinal cord

It has been shown that polyethylene glycol (PEG) can reseal membrane disruption on the spinal cord, but only high concentrations of PEG have been shown to have this effect. Therefore, the effect of PEG is somewhat limited, and it is necessary to investigate a new approach to repair spinal cord injury. This study assesses the ability of 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(poly (ethylene glycol)) 2000] (DSPE-PEG) to recover physiological function and attenuate the injury-induced influx of extracellular ions in ex vivo spinal cord injury. Isolated spinal cords were subjected to compression injury and treated with PEG or DSPE-PEG immediately after injury. The compound action potential (CAP) was recorded before and after injury to assess the functional recovery. Furthermore, injury potential, the difference in gap potentials before and after compression, and the concentration of intracellular ions were used to evaluate the effect of DSPE-PEG on reducing ion influx. Data showed that the injury potential and ion concentration of the untreated, PEG and DSPE-PEG group, without significant difference among them, are remarkably higher than those of the intact group. Moreover, the CAP recovery of the DSPE-PEG and PEG treated spinal cords was significantly greater than that of the untreated spinal cords. The level of CAP recovery in the DSPE-PEG and PEG treated groups was the same, but the concentration of DSPE-PEG used was much lower than the concentration of PEG. These results suggest that instant application of DSPE-PEG could effectively repair functional disturbance in SCI at a much lower concentration than PEG.

Electric field stimulation protects injured spinal cord from secondary inflammatory response in rats

Objectives: To investigate acute beneficial effects of electrical field stimulation (EFS) on secondary inflammatory response in spinal cord injury (SCI) rats.OBJECTIVES To investigate acute beneficial effects of electrical field stimulation (EFS) on secondary inflammatory response in spinal cord injury (SCI) rats. METHODS Sprague-Dawley (SD) rats were divided into three groups,sham group rats received laminectomy only, control group rats were subjected to SCI only, and EFS group rats received EFS immediately after the injury. During the 30-min-stimulation, the injury potential modulated to 0 ± 0.5 mV by EFS. At 12h, 24h and 48h after the surgery, the rats in each group were sacrificed. Immunofluorescence staining for macrophage marker (ED-1), the tautomerase activity of macrophage inhibitory factor (MIF) assay and real-time PCR analysis for interleukin-1β (IL-1β) and matrix metalloproteinase-9 (MMP-9) were performed. RESULTS Compared to the rats in control group, the rats treated with EFS presented less ED-1 positive cells 12h (P <; 0.05), 24h (P <; 0.01) and 48h (P <; 0.05) after the surgery and showed a lower MIF tautomerase activity 12h (P <; 0.01), 24h (P <; 0.01) and 48h (P <; 0.01) after the surgery. Moreover, EFS significantly decreased the mRNA levels of IL-β (P <; 0.05) and MMP-9 at 48h (P <; 0.01) after the injury. CONCLUSIONS EFS could attenuate secondary inflammatory response of injured spinal cord shortly after SCI, and EFS treatment could be a candidate for SCI therapy.

Combination of applied electric field and polyethylene glycol effectively enhance functional recovery in acute spinal cord injury of rats

Applied electric field stimulation (EFS) can reduce extracellular Ca2+ influx and consequently enhance functional recovery after spinal cord injury (SCI). However, the influx of Ca2+ continued through disrupted membranes when EFS completed. As polyethylene glycol (PEG) can reseal the damaged membranes, we proposed a hypothesis that combination therapy of EFS and PEG may effectively prevent Ca2+ influx and further promote functional recovery in rats subjected to SCI. Rats were randomly divided into three groups: saline group, treated with saline only; control group, treated with EFS and saline; and experimental group, treated with EFS and PEG. The effects of EFS combined with PEG were assessed by means of injury potential and Basso, Beattie, and Bresnahan (BBB) scores. Data showed that the injury potential at the moment of EFS termination in experimental group was significantly smaller compared with that in control group, but higher than that in saline group. Moreover, the BBB scores in experimental group were significantly higher than those in other groups. These findings suggest that combination therapy of EFS and PEG could further enhance functional recovery in acute SCI of rats.

Injury potentials of spinal cord in ex vivo compression injury model.

The effect of applied electric field on neuroprotection and axonal regeneration has been studied in previous studies of acute spinal cord injury (SCI). However, due to the complexity of the microenvironment of the lesion site, the underlying mechanism of applied electric field is not yet fully understood. Thus, the injury potential, a significant index of the microenvironment change, was investigated in ex vivo spinal cords compression injury. Spinal cords isolated from rat were cultured in a double sucrose gap recording chamber. Both compound action potential (CAP) and injury potential were measured. Compression induced the decreasement of compound action potential, but the amplitude of CAP increased gradually after decompression. Compression also lead to the appearance of injury potential, represented by the voltage difference between the gap potential before and after compression, and the injury potential decreased with time logarithmicly after decompression. Intracellular Na(+) and Ca(2+) concentrations were measured and results showed that after injury these ions flowed into intracellular space. Therefore, the current approach can provide a basis for investigating the formation mechanism of the injury potential and help understand the pathophysiology of the SCI.The effect of applied electric field on neuroprotection and axonal regeneration has been studied in previous studies of acute spinal cord injury (SCI). However, due to the complexity of the microenvironment of the lesion site, the underlying mechanism of applied electric field is not yet fully understood. Thus, the injury potential, a significant index of the microenvironment change, was investigated in ex vivo spinal cords compression injury. Spinal cords isolated from rat were cultured in a double sucrose gap recording chamber. Both compound action potential (CAP) and injury potential were measured. Compression induced the decreasement of compound action potential, but the amplitude of CAP increased gradually after decompression. Compression also lead to the appearance of injury potential, represented by the voltage difference between the gap potential before and after compression, and the injury potential decreased with time logarithmicly after decompression. Intracellular Na+ and Ca2+ concentrations were measured and results showed that after injury these ions flowed into intracellular space. Therefore, the current approach can provide a basis for investigating the formation mechanism of the injury potential and help understand the pathophysiology of the SCI.

Oscillating field stimulation promotes recovery after spinal cord injury in rats: Assessment using behavioral, electrophysiological and histological evaluations.

OBJECTIVES We explored whether oscillating field stimulation (OFS) could efficiently promote motor function recovery in rat model of spinal cord injury. METHODS SD rats with spinal cord injury induced by Allen method was divided into two groups, experimental group rats received active stimulator units and control group rats received sham (inoperative) stimulator units. The electric field intensity was 600μV/mm, and the polarity alternated every 15 min. RESULTS The results showed that the experimental group rats had significantly better locomotor function recovery (inclined-plane testing and modified Tarlov motor grading scale) 5 weeks after the injury (P<;0.05). OFS treatment significantly decreased motor evoked potential (MEP) latency differences and amplitude differences 4 w and 8 w post injury (P<;0.05, P<;0.01). Furthermore, the number of axons was quantified by immunofluorescence staining of nerve fiber (NF), increased axon numbers were observed at 4 w and 8 w in experimental group (P<;0.05). CONCLUSIONS These findings suggest OFS can promote motor function recovery in SCI rats, and this effect may be related to the improving axon regeneration in spinal cord.Objectives: We explored whether oscillating field stimulation (OFS) could efficiently promote motor function recovery in rat model of spinal cord injury. Methods: SD rats with spinal cord injury induced by Allen method was divided into two groups, experimental group rats received active stimulator units and control group rats received sham (inoperative) stimulator units. The electric field intensity was 600μV/mm, and the polarity alternated every 15 min. Results: The results showed that the experimental group rats had significantly better locomotor function recovery (inclined-plane testing and modified Tarlov motor grading scale) 5 weeks after the injury (P<;0.05). OFS treatment significantly decreased motor evoked potential (MEP) latency differences and amplitude differences 4 w and 8 w post injury (P<;0.05, P<;0.01). Furthermore, the number of axons was quantified by immunofluorescence staining of nerve fiber (NF), increased axon numbers were observed at 4 w and 8 w in experimental group (P<;0.05). Conclusions: These findings suggest OFS can promote motor function recovery in SCI rats, and this effect may be related to the improving axon regeneration in spinal cord.