Biomedical Engineering: Applications, Basis and Communications

Poor compatibility between blood and metallic coronary artery stents is one reason for arterial restenosis. Immobilization of heparin on stent's surface is feasible for improving compatibility. We examined possible surface-coupling agents for anticoagulant agent immobilization. Hexamethylene diisocyanate (HMDI) was examined as surface-coupling agent to activate 316L stainless steel (e.g. stent material). Afterwards, we grafted PEG on the HMDI activated surface to provide heparin with higher conformational freedom and a more hydrophilic environment. The effectiveness of HMDI activated and PEG grafted surface was confirmed by FTIR, XPS, and water contact angle test. Heparin was then immobilized onto the activated 316L stainless steel. The heparin surface density was 9.5 μg/cm². Sessile drop water contact angles showed that the heparingrafted surface is even more hydrophilic than the PEG grafted one. The function of grafted heparin was evaluated by antithrombrin III (ATIII) adsorption testing and SEM. The surface with heparin grafting shows better ATIII binding ability and hemocompatibility than the native one.

The asymmetric porphyrins with different substituents show various bioactivities in biomedical application. In this study, a series of asymmetric porphyrins with varying proportion of substituents, such as hydroxyphenyl and aminophenyl, were synthesized and characterized to evaluate their cell uptake, intracellular localization, cytotoxicities and phototoxicities in vitro. Among these synthesized porphyrins, 5-(4-aminophenyl)-10,15,20-tri-(4-hydroxyphenyl)-21,23H-porphyrin (porphyrin 5), which was mainly localized in mitochondria and with high quantum yields of singlet oxygen, is a potential candidate for photodynamic therapy. The effective phototoxicity of porphyrin 5 is mainly due to the higher extent in the cells and the selective mitochondria-localization. Comparing the partition coefficients of porphyrin derivatives, the best cellular uptake performs apparently with a partition coefficient (log p) ranging from about 1.7 to 1.9. In summary, higher quantum yields of singlet oxygen, and more specific mitochondrial localization of porphyrin 5 demonstrate its potential application in photodynamic therapy.

It is important to ensure the data security of biosignals transmitted by a wireless network. This paper proposes a mobile-care device using Tame Transformation Signatures (TTS), which is a digital signature scheme from the family of asymmetric public key systems to encrypt the electrocardiogram (ECG) data. TTS has the advantages of high security, fast key generation, complex algorithm, less calculations and low signature delay. The proposed system consists of a mobile-care device to measure ECG signal, a key center to generate key pair, and a monitor center. The proposed ECG mobile-care device adopts the TI MSP430F449 microprocessor as the kernel and generates 8-byte hash codes and 10-byte signatures to sign the data. And the mobile-care device transmits the signed data through a wireless network to the server to decrypt. This paper describes the design and implementation of the proposed system in detail and also completely verifies the validity of the proposed system.

The well being of the fetal is one of the primary issues in prenatal obstetric care. The assessment of fetal well being is usually practiced by observing the fetal heart rate and monitoring its patterns. Ultrasound based instruments are commonly used for this purpose in hospitals, but they are not suitable for home monitoring applications because of several known reasons. This work is focused around the development of a web-based prototype system for routine fetal home monitoring application. This is helpful in management of complex pregnancies. The presented system is used for recording fetal heart sound in the woman's restful hours at home and makes it available to the physician remotely via the internet. Transmitted data is then processed by an innovative methodology for deriving crucial results of diagnostic importance. After careful examination of these results, status report is electronically e-mailed to the expectant mother for a ready reference and subsequent action. The system has been tested on 20 pregnant women with varied gestation age and pathological conditions. The resultant performance was compared with a standard ultrasound based device commonly used in hospitals. It is found that the developed fetal health care system provides promising result that enables fetal monitoring in low stress, and relaxed home environment. It also supports rapid information flow, and provides quick accessibility to information at the point of decision.

Blood oxygenation level dependent functional magnetic resonance imaging technique was used to explore the antinociceptive effect of morphine in the rat brain under α-chloralose and isoflurane anesthesia. Formalin was used as a pain-testing model which could produce significant activation in various brain areas. The results also showed that morphine pretreatment modulate neurovascular activities evoked by formalin stimulation, especially in cingulate cortex, somatosensory cortex, caudate putamen, visual cortex, and hippocampus. The present study identified the brain areas involved in modulating nociception.

Electricity has been shown to exhibit significant effects on immunological responses in many studies. In this study, an electrostatic filed induced device was first applied to the macrophage cell culturing process. Mouse macrophage-like cells J774 A.1 were exposed to the electrostatic field of 1.5 kV for 1, 2, and 6 days, respectively. The results show that the electrostatic field can inhibit cell proliferation and TNF-α secretion in six days. Cell proliferation is decreased and TNF-α secretion is increased with increasing voltage applied from 0 kV to 0.8 kV and 1.2 kV of the electrostatic fields.

Modified calcium silicate cement had previously been developed as a dental retrograde filling. It had great sealing ability, good biocompatibility, and anti-bacterial properties. However, its clinical application was limited by a long setting time and poor handling property. In previous study,^{1, 2} the setting property of PSC was greatly improved due the sol-gel process, without the addition of transition metal element.

In this study, different ratio of starting material of PSC was prepared. The composition of each group was also altered with the ratio of the starting materials according to the result of XRD pattern. There is no significant difference in pH variation profile between each group. Even though low C₃S/C₄AF ratio (DX631 and DX541 groups) possessed high initial strength at first 24 hours after hydration, there was no increase in strength ever since according to the result of microhardness. However, the groups with high C₃S/C₄AF ratio (DX811 and DX721 groups) possessed relatively low initial strength at 24 hours after hydration, but the strength increased rapidly and continuously at least for the next six days of hydration. Moreover, the peak intensity of hydration product (Portlandite) on XRD pattern in DX811 group was much higher than other three groups, and this was also in agreement with the result of microhardness. DX811 group is determined to be the optimal one for the further development in the application as root-end filling materials.

A versatile, low cost, low power electrical stimulator for urinary incontinence is described in this paper. The device is compact with a simple user interface. The device enables precise adjustments to the frequency, pulse width, mode (burst or continuous), and amplitude of the output current. It is valuable for experimental and clinical applications. Detailed circuit design, complete specification, and test are described.