Microfluidic system for detection of alpha-thalassemia-1 deletion using saliva samples.

This current study presents a new miniature, integrated system capable of rapid detection of genetic deletion from saliva samples. Several critical modules including a genomic DNA (gDNA) extraction module, a polymerase chain reaction (PCR) module, and an external optical detection module are integrated into the system. Silica-modified magnetic beads are first incubated with saliva in an extraction chamber with a cell lysis solution. This is followed by the collection of released gDNA onto the surface of the microbeads, which is then further purified and concentrated utilizing a magnetic field generated by an on-chip array of microcoils. Then, genetic deletion of human genes can be specifically amplified by the on-chip PCR module and is immediately detected using the optical detection module. Experimental results show that high-quality gDNA with an average concentration of 50.45 ng/microL can be extracted from 100 microL of saliva. The detection of a mutated alpha-globin gene associated with alpha-thalassemia-1 of southeast Asian (SEA)-type deletion can be completed within less than 1 h. Moreover, the detection limit of the system is found to be 12.00 pg/microL with a high sensitivity up to 90%. Consequently, the proposed saliva-based miniature system can provide a powerful platform for rapid DNA extraction and detection of genetic diseases.

Magnetic-bead-based microfluidic system for ribonucleic acid extraction and reverse transcription processes.

This paper presents a new integrated microfluidic chip that automatically performs ribonucleic acid (RNA) extraction and reverse transcription (RT) processes. The microfluidic system consists of a microfluidic control module and a magnetic bio-separator. The microfluidic control module can perform pumping and mixing of small amount of fluids and subsequent purification and concentration of RNA samples by incorporating with the magnetic bio-separator consisting of 2-dimension twisted microcoils. Notably, the magnetic bio-separators are developed either to generate the required magnetic field to perform the separation of magnetic beads or to work as a micro-heater to control the temperature field for the following RT process. Experimental results show that the total RNA can be successfully purified and extracted by using magnetic beads and the subsequent RT processing of the RNA can be performed automatically. Total RNA is successfully extracted and purified from T98 cells utilizing the microfluidic system, which is comparable with the conventional methods. The whole automatic procedure of RNA sample extraction only takes 35 min, which is much faster than the conventional method (more than 2 h). As a whole, the developed microfluidic system may provide a powerful platform for rapid RNA extraction and RT processes for further biomedical applications.

The role of astragaloside in regeneration of the peripheral nerve system.

The aim of this study was to evaluate peripheral nerve regeneration across a 15-mm gap in the sciatic nerve of the rat, using a silicone rubber nerve guide filled with different concentrations of astragaloside (0, 50, 100, and 200 microM). Collagen was also filled in the chambers to prevent the astragaloside from leakage. At the end of 8 weeks, animals from the group treated with astragaloside, especially at the concentration of 50 microM, had a higher rate of successful regeneration across the wide gap, a significantly larger number of myelinated axons, and a greater evoked action potential than the control group. However, the high-dose astragaloside (200 microM) completely reversed this positive effect of growth-promoting capability and inhibited nerve regeneration. Thus, astragaloside plays a dual role in anastomosis, being salutary in aiding the growth of axons in peripheral nerve but also detrimental, terminating the nerve regenerative processes if improperly applied.

Effect of bilobalide on peripheral nerve regeneration.

The present study provides in vivo trials of silicone rubber chambers filled with different concentrations of bilobalide (0, 50, 100, 200, 400 microM) to bridge a 15 mm sciatic nerve defect in rats. Collagen was also filled in the chambers to prevent the bilobalide from leakage. Histological and electrophysiological techniques were used to evaluate the functional recovery of the nerve. At the conclusion of 8 weeks, animals from the group treated with the bilobalide, especially at the concentration of 200 microM, had a higher rate (40%) of successful regeneration across the wide gap and a significantly larger number of myelinated axons (4094 +/- 1555), compared to only 10% and 2485 in the control group. However, the high dose bilobalide (400 microM) completely reversed this positive effect of growth-promoting capability and inhibited nerve regeneration. Only 10% of the animals treated with the high dose bilobalide had regenerated cables within the silicone rubber chambers. These results indicated that bilobalide could be involved in both positive and negative effects on regenerating nerves. Therefore, whether a proper dosage of bilobalide is used or not plays a critical factor in deciding if it can sustain nerve regeneration over long gaps.

4G/5G promoter polymorphism of plasminogen activator inhibitor-1, lipid profiles, and ischemic stroke.

The 4G allele of common 4G/5G polymorphism in the promoter of the plasminogen activator inhibitor-1 (PAI-1) gene is associated with increased PAI-1 transcription and has been proposed as a candidate genetic risk factor for thrombotic diseases. We investigated the relationship between this polymorphism and lipid profiles and stroke risk. One hundred patients with ischemic stroke and 150 age- and sex-matched control subjects were enrolled. PAI-1 genotype was determined with the use of polymerase chain reaction and restriction-length analysis. Genotype distribution in the stroke group was 40% 4G/4G, 46% 4G/5G, and 14% 5G/5G; in the control group it was 38.7% 4G/4G, 45.3% 4G/5G, and 16% 5G/5G. The allele and genotype frequencies of 4G/5G polymorphism were not different between the stroke and control groups. Control subjects who were homozygous for the 4G allele had significantly lower high-density lipoprotein (HDL) cholesterol levels than did those carrying the 5G allele (51.2 +/- 11.8 vs 58.4 +/- 15.8 mg/dL; P =.002). In the control group, regression analysis revealed a significant contribution of 4G/4G genotype to increased triglyceride (P =.042) and to decreased HDL cholesterol (P <.001) levels. Our findings suggest that PAI-1 4G/5G promoter polymorphism alone is not associated with ischemic stroke. However, this polymorphism influences lipid levels, and the underlying mechanism must be determined.