Biomedical subjects

J-C Tsai

Publications and source records attributed to J-C Tsai.

9 recordsLinked to original sources

PubMed2006

Lamivudine reverses severe acute hepatitis B and pancytopenia after renal transplantation: a case report.

Pancytopenia is rare after acute hepatitis B infection. The use of lamivudine in the treatment of acute hepatitis B-associated pancytopenia in renal transplant recipients has not been documented. Herein we reported a 21-year-old woman who was infected with acute hepatitis B 6 months after renal transplantation, a condition complicated by pancytopenia. Lamivudine reversed the acute hepatitis in 1 month and the pancytopenia after 3 months, without a change in renal function. Lamivudine was maintained for 2 years without a hepatitis flare-up after 4 years.

Adult↗

PubMed2005

Granular packings sheared in an annular channel: flow localization and grain size dependence.

We investigate experimentally a quasistatic flow of glass beads in an annular channel, in which particles are packed and sheared from above under a constant normal load. The experiments utilize techniques of refractive-index-matched fluorescent imaging to determine the motion of individual particles and the velocity fields inside the sheared packing. We demonstrated in a previous paper [Phys. Rev. E 70, 031303 (2004)] that an ordering transition has a significant impact on the velocity profile. Here, we report the effects of layer thickness, channel width, and particle size on the internal velocity field. For very thin layers, the grain velocity exhibits a linear vertical profile. As the layer thickness increases, a strongly nonlinear velocity profile emerges, with particle motion that is largely localized to a narrow region (shear band) near the driving surface. Once the packing has reached its steady state, the velocity field is insensitive to the size of grains being used--the velocity profile does not scale with grain size. However, the vertical decay of grain velocity becomes significantly steeper as the horizontal width of the channel decreases. In addition, we demonstrate that changing the direction of shearing generates an anomalous mobility of grains in the deep interior that is sensitive to particle size. The transient grain motion is accompanied by an abrupt volume compaction and a gradual recovery as the shearing proceeds. Reviewing results from this and other works reveals that the velocity profiles of granular shear flows are often geometry specific. We present a heuristic continuum model that qualitatively captures the shear banding observed in this geometry.

Journal Article↗

PubMed2005

A chiral granular gas.

Inspired by rattleback toys, we created small chiral wires that rotate in a preferred direction on a vertically oscillating platform and quantified their motion with experiment and simulation. We demonstrate experimentally that angular momentum of rotation about particle centers of mass is converted to collective angular momentum of center-of-mass motion in a granular gas of these wires, and we introduce a continuum model that explains our observations.

Journal Article↗

PubMed2005

In-patient medical resource utilization for high-level cervical spinal cord injury without bone fracture in Taiwan.

STUDY DESIGN: Retrospective review of secondary data obtained from the Bureau of National Health Insurance (BNHI) on medical resource utilization in in-patient cervical spinal cord injury patients in Taiwan. OBJECTIVES: Since the start of the National Health Insurance Program in Taiwan in 1995, costs have continued to increase each year. High-level cervical spinal cord injury, a catastrophic illness, consumes a large amount of medical resources. Appropriate control of in-patient costs for these patients is mandatory. Analyses of the factors influencing the health-care costs of these patients are needed, so cost-containment policies can be established by the BNHI to conserve health-care resources. SETTING: Health-care institutions throughout Taiwan. METHODS: We obtained secondary data on a randomized basis for diagnostic codes 952.00, 952.01, 952.02, or 952.03 of the International Classification of Diseases, Ninth Revision, Clinical Modification from the BNHI files of annual in-patient expenses during the period from 1998 to 2000. There were 184 hospital admission records studied. RESULTS: The lengths of stay and in-patient costs were significantly different among different hospital types. Length of stay also was statistically different according to patient, gender, and age. The lengths of stay and in-patient costs were influenced by the hospital accreditation level and patient gender. Medical orders were influenced by patient age. CONCLUSIONS: Basic and selective diagnostics and therapeutics for high-level spinal cord injury without bone fracture should be established. Thus, patient needs for appropriate medical care will be met and overuse of medical resources will be prevented. Communication among doctors also should be strengthened.

Adolescent↗

PubMed2004

Slowly sheared dense granular flows: crystallization and nonunique final states.

Simultaneous time-resolved measurements of internal structure, granular volume, and boundary shear force are reported for dense granular packing steadily sheared under a fixed normal load. We identify features of the crystallization transition for a deep shear flow, whose height-dependent local mean velocity spans more than five orders of magnitude. This structural change is accompanied by a significant decrease of granular volume and shear force, with a more rapid falloff of particle velocity with depth than occurs in the disordered state. Boundary conditions can have a profound influence on the crystallization of the entire packing. We find that continuously sheared flow can exhibit nonunique final states even under identical boundary conditions; a few cycles of oscillatory pretreatment can initiate states that evolve into either a crystallized or a disordered final state after long-term unidirectional shearing. On the other hand, the disordered state can be stabilized after being sufficiently compacted by unidirectional shear. These experiments raise interesting questions about how prior history is recorded in the internal structure of granular packings, affecting their instantaneous rheology and long-term evolution in response to shear.

Journal Article↗

PubMed2004

Scanning laser polarimetry in patients with acute angle-closure glaucoma.

PURPOSE: To detect differences in retinal nerve fibre layer (RNFL) measurements between patients with acute angle-closure glaucoma (AACG) and normal subjects using scanning laser polarimetry. METHODS: This was a comparative cross-sectional study, where 32 eyes of 32 patients with AACG and 28 eyes of 28 normal subjects were imaged using scanning laser polarimetry (The Nerve Fibre Analyzer GDx, Laser Diagnostic Technology Inc., San Diego, CA, USA). The average RNFL thickness in four quadrants and various GDx parameters between the two groups were compared using Mann-Whitney tests with Bonferroni correction. RESULTS: There were no significant differences in RNFL measurements for the average thickness, ellipse average, inferior, superior, nasal, and temporal average values between the AACG eyes and normal eyes. There were significant differences in some GDx parameters, including superior/nasal ratio (P=0.036), superior ratio (P=0.01), the GDx number (P=0.003), inferior ratio (P<0.001), maximum modulation (P<0.001), and ellipse modulation (P<0.001). CONCLUSIONS: Various GDx parameters exhibit significant changes in patients following short-duration AACG episodes, making GDx RNFL measurements useful for the diagnosis and follow-up of AACG.

Acute Disease↗

PubMed2003

Internal granular dynamics, shear-induced crystallization, and compaction steps.

Internal imaging using index matching, and sensitive volume measurement, are used to investigate the spatial order and dynamics of a deep disordered layer of spheres sheared under a fixed load. Shearing triggers a crystallization transition accompanied by a step compaction event. The delay preceding the transition depends strongly on the layer thickness and can require a translation of about 10(5) particle diameters. The mean velocity varies with depth by more than five decades, and its profile is qualitatively altered by the transition.

Journal Article↗

PubMed2003

Tape stripping and sodium dodecyl sulfate treatment increase the molecular weight cutoff of polyethylene glycol penetration across murine skin.

Prior studies in hairless mice have demonstrated that acute barrier disruption by acetone treatment increases the molecular weight (MW) cutoff of polyethylene glycol (PEG) penetration through the skin. The objective of the present study was to further investigate the dependence of permeability on MW with different forms of barrier disruption. A series of PEGs ranging in MW from near 300 to over 1000 Da were used to study the effects of tape stripping and sodium dodecyl sulfate (SDS) treatment on the MW permeability profiles of mouse skin in vitro. The 12-h percutaneous penetration of all the PEG 300, 600, and 1000 oligomers generally increased as a function of transepidermal water loss (TEWL) of the skin, either tape-stripped or SDS-treated. In addition, the total penetration of PEG oligomers across control skin, and skin tape-stripped and SDS-treated to different degrees of barrier disruption progressively decreased with increasing MW. There were no significant differences in the percutaneous penetration of the PEG oligomers between skin tape-stripped and SDS-treated to the same degree of barrier disruption. The penetration enhancement relative to control skin was more prominent with larger molecules. The MW cutoff for skin penetration increased with the degree of barrier disruption irrespective of the treatment applied, and was 986 Da (tape stripping) and 766 Da (SDS treatment) at TEWL levels in the range 10-20 g/m(2) per h in comparison with 414 Da for control skin. In accordance with previous findings in acetone-treated mouse skin, the results strongly suggest that, irrespective of the form of barrier disruption applied, not only higher amounts but also more varieties of chemicals (larger molecules) may penetrate skin with a compromised barrier than normal skin.

Administration, Cutaneous↗

PubMed2002

In vitro/in vivo correlations between transdermal delivery of 5-aminolaevulinic acid and cutaneous protoporphyrin IX accumulation and effect of formulation.

BACKGROUND: Photodynamic therapy (PDT) using topical application of 5-aminolaevulinic acid (ALA) has been widely reported for the treatment of a variety of neoplastic and non-neoplastic cutaneous diseases. Although different formulations containing variable amounts of ALA have been applied in PDT, the dose-response relationships between transdermal ALA delivery and cutaneous protoporphyrin IX (PpIX) accumulation have not been studied. OBJECTIVES AND METHODS: The objectives of this study were to investigate the effect of permeability barrier function, ALA concentration and formulation on the in vitro penetration of ALA through nude mouse skin and cutaneous PpIX formation at 2 h following a 2-h application of ALA to nude mouse skin in vivo, and to delineate the relationships in between. RESULTS: Results demonstrated that variations in barrier integrity, in addition to ALA concentration, profoundly influenced ALA delivery to generate PpIX. Saturable correlations were found to exist between PpIX concentrations in both the epidermis and dermis in vivo and its transdermal flux in vitro, and the relationships were well described by the Emax model. The established correlations based on pure aqueous solutions were applicable to different formulations containing hydroxypropylmethylcellulose as the gelling agent and ethylenediamine tetraacetic acid as the iron chelator. Moreover, incorporation of desferrioxamine, another iron chelator, in the formulation prolonged cutaneous PpIX accumulation in the skin in comparison with 3% ALA aqueous solution, but the peak PpIX levels were not increased. Application of a liposomal formulation resulted in similar prolongation in ALA-induced PpIX accumulation, as well as better epidermal targeting. CONCLUSIONS: Knowledge of the dose-response relationships and the effect of formulation is important for designing optimal formulations and treatment schedules for topical ALA-PDT.

Administration, Cutaneous↗