Biomedical Engineering: Applications, Basis and Communications

Tissue engineering is a new approach for articular cartilage repair. The aim of the present article was to review the current status of cartilage tissue engineering researches. The scaffold materials used for cartilage tissue engineering, the in vitro, in vivo studies and the clinical trials were all reviewed. Our researches about in vitro cartilage tissue engineering with new type bioactive scaffold and preliminary animal studies results will also be described. The scaffold was tricopolymer made from gelatin, hyaluronan and chondroitin. Chondrocytes seeded in tricopolymer showed in vitro engineered cartilage formation. The engineered cartilage constructs were implanted into knee joints of miniature pigs for animal study.

Our previous study indicated that montmorillonite (MMT for short) was pharmaceutically feasible to be used as a carrier of an anticancer drug 5-FU. Emphasis of this study is thus placed on the toxicity of MMT to address whether it is clinically safe for practical use. Hematological data of rats model showed that the rats administered with oral MMT had significant increases in hemoglobin (Hb) concentration, Hamatocrit and RBC count than those of oral PBS buffer (p<0.05). However, MCV, MCH, MCHC, WBC Count and WBC were not statistically significant different between experimental and control group (p>0.05). Hematological analysis for intravenous injection also showed no statistically significant differences between experimental and control group (p>0.05).

Biochemical analysis pointed out that compared to oral PBS there was not only a significant decrease of sodium (Na⁺) and chloride (Cl⁻) ion (p<0.05) in plasma for oral MMT, but also an extremely significant decrease in the plasma calcium (Ca²⁺)(p<0.01). On the other hand, after intravenous injection of MMT compared to control group, a significant increase (p<0.05) in ALT (SGPT), and an extremely significant decease (p<0.01) in plasma potassium (K⁺) were observed. It is deserved to mention here that histochemical examinations were all normal, suggesting that montmorillonite may be considered non-toxic. Regarding histopathological sections of rats, there were all in normal ranges irrespective of experimental or control group.

For bacterial model, a generally considered safe and non-pathological microorganism Saccharomyces cerevisiae was used as the model yeast to be administrated with various extracellular doses of MMT, montmorillonite-K₆Fe(CN)₃ (MMTK), or montmorillonite-K₆Fe(CN)₃-sodium alginate (MMTK-SA) for toxicological assessments. Dose-response analysis indicated that the toxicity ranking as Lannate ≫ MMTK > MMTK-SA ≫ MMT-SA > MMT according to EC₀ or EC₅₀ line. These all suggested that MMT alone is much less toxic than Lannate and potassium hexacyanoferrate(III). Apparently, it was concluded that MMT alone could be considered non-toxic to S. cerevisiae and Wistar rat for myriads of applications.

The aim of this study was to establish a scoring system, Neonatal Facial Image Scoring System (NFISS), for investigating the pain responses in neonates during routine venipuncture. We collected 1998 facial images from 19 infants during the first phase of this study and identified twelve features of the facial image: normalized scale for NFISS (scale from 0-15), including brow bulge (0-2), vertical brow furrowing (0-1) and short distance (0-1), brow lowering (0-1), eyes close (0-1), bulging eyes (0-2), eye-eye furrowing (0-1), cheek bulge (0-1), nasal-labial furrowing (0-2), mouth open and stretch (0-1), lip purse (0-1) and taut tongue (0-1). During the second evaluation phase, with 2770 images from 31 newborn infants (average age: 2.85°”.027 days), the pain responses were graded on the NFISS scale. Two peak score values during a time course of baseline-venipuncture-recovery (3-3-10 min) were found with needle piercing and needle withdrawal. The reliability of the score analysis was evaluated using 492 randomly selected images out of the 2770 images. The results for intra-scorer (author, one week interval) and inter-scorer (author and one experienced nurse) has correlation coefficients of 0.916 and 0.826, respectively.

A pH-sensitive membrane for colon-specific drug delivery was prepared by glycine-immobilization on poly (ethylene-co-vinyl alcohol) (Gly-EVAL) that can enhance the permeability of hydrocortisone at pH 7.4 and resist drug permeation at pH 2.0 or in gastric juice. As the results of drug releasing profile, it is proposed that the electrical repulsion occurring between adjacent carboxylate ions at pH 7.4 on Gly-EVAL causes the higher permeation rate of hydrocortisone. Consequently, the hydrocortisone coated by Gly-EVAL can escape from degradation in acid environment and release significantly in neutral or weak basic pH values, which is ideally suitable for local treatment of ulcerative colitis.

Judging from the continuous increase in population suffering from chronic illnesses in the past 30 years in Taiwan, we can predict that the number of diabetes victims will reach 1.5 million in 15 years. This increase is global. According to an estimate provided by WTO, one out of two diabetes sufferers is not identified as the illness victim. An estimate of 100 million people in the world are diabetes patients. Although there is currently no way to completely cure diabetes, this disease can be controlled, monitored, and improved through education, research and development of new medication and techniques. However, the quality control of glucose monitoring has posed a stubborn problem to all fields related to the medical realm in Taiwan. By contrast, there is already a well-developed management system of blood glucose measurement in the West. All the standard-setting organizations, such as NCCLS and ISO, have published relevant Standard Operation Procedure (SOP). In Taiwan, we haven't had any similar certification mechanism. It is urgent for Taiwan to establish such standards specifically for the yellow race. Now, CNLA has introduced ISO 17025 in clinical test. Although it offers a general guideline, it doesn't specify detailed operation steps. As a result, it cannot offer an accurate result in blood glucose measurement. This paper is focused on ways to evaluate the uncertainty of measurement on blood glucose level based on the standard environment lab for medical device testing in the biomedical engineering department of National Taiwan University Hospital, so as to establish a function of uncertainty of measurement on blood glucose level and make it a stepping stone for certification of the measurement.

Degeneration of the intervertebral disc (IVD) and associated spinal disorders are a leading cause of morbidity resulting in substantial pain and increased health cost. Current treatment options may relieve some clinical symptoms but will never stop further degeneration in the IVD. In recent years, several investigations have been carried out trying to regenerate IVD tissue. These biomedical engineering methods aim to retard or even reverse the degenerative process and possibly regain a healthy IVD. In this review, recent progresses on each category of biomedical engineering approaches will be briefly introduced.

The thermal and degradable properties of carbodiimide (EDC) or glutaraldehyde (GTA) cross-linked gelatin membranes have been investigated in order to evaluate the effects of different concentrations of two kinds of cross-linking reagent on the stability of membranes. In the thermogram recorded from a gelatin membrane cross-linked with EDC solution, the endothermic peak of 0.8% EDC cross-linking gelatin was centered at about 61°C that was higher than other samples treated with EDC solutions. Denaturation temperature (Td) of gelatin samples increased on increasing EDC concentration (0.2% to 0.8%), in agreement with the simultaneous increased of the extent of cross-linking. But increasing GTA concentration from 0.05% to 0.6%, the Td values of gelatin samples were decreased from 66.2°C to 56.3°C . In addition, two endothermic peaks were observed in 0.4% and 0.6% GTA cross-linking groups because of the GTA concentration was too high to complete cross-linking reaction. Therefore, partial of gelatin membrane was cross-linked completely but others were not. In the thermogravimetric analysis, the proportion of cracking endothermic peak of 0.6% GTA cross-linking gelatin (g15G0.6) was higher than the peak of 0.6% EDC cross-linking gelatin (g15C0.6). Therefore, g15G0.6 cracked to smaller molecules has to absorb more calorific capacity than g15C0.6. The increase in the strength of covalent binding on increasing the proportion of endothermic peak was evident. The results of degradable rate were in agreement with the lower concentration of cross-linked reagent the faster degraded rate of gelatin membrane. The MTT assay showed that 15% gelatin cross-linked by 0.8% EDC has the least cytotoxicity, and cell activity of this group was similar to control group (blank dish). As the concentration of GTA in gelatin membranes was down to 0.05% or 0.1% the cell viability was returned to approach the value of control group.

A high input impedance, high common mode rejection ratio, fixed gain (×100) amplifier is proposed for recording biopotential signals. This miniature amplifier affords the feature of power saving. It can continuously function for as long as 3 months with a small battery (3.3 V, 2.2 g). A practical application of this amplifier for ECG recording has shown that it has great potential for recording other biomedical signals. Hence, this amplifier can be used as a building block at the front end of most biomedical systems. Detailed design considerations and circuit implementation of this amplifier are described to facilitate its acceptance as a common module for this purpose.