Biomedical subjects

Chien-Fu Chen

Publications and source records attributed to Chien-Fu Chen.

3 recordsLinked to original sources

PubMed2006

Effects of bulk dissipation on the critical exponents of a sandpile.

Bulk dissipation of a sandpile on a square lattice with the periodic boundary condition is investigated through a dissipating probability f during each toppling process. We find that the power-law behavior is broken for f>10(-1) and not evident for 10(-1)}>f>10(-2). In the range 10(-2)>or=f>or=10(-5), numerical simulations for the toppling size exponents of all, dissipative, and last waves have been studied. Two kinds of definitions for exponents are considered: the exponents obtained from the direct fitting of data and the exponents defined by the simple scaling. Our result shows that the exponents from these two definitions may be different. Furthermore, we propose analytic expressions of the exponents for the direct fitting, and it is consistent with the numerical result. Finally, we point out that small dissipation drives the behavior of this model toward the simple scaling.

Journal Article↗

PubMed2005

Cognitive dysfunction after acute lacunar infarct.

Vascular dementia and vascular cognitive impairment have attracted more attention recently due to their association with increased risk of death and institutionalization. The purpose of the present study was to detect and identify the characteristics of cognitive impairments during the early stage of lacunar stroke. The subjects consisted of 23 consecutive first-ever acute lacunar infarction patients who were admitted to the Department of Neurology, Kaohsiung Municipal Hsiao-Kang Hospital, Taiwan, from November 2001 to October 2002. The National Institutes of Health Stroke Scale and Cognitive Abilities Screening Instrument (CASI) were used to evaluate stroke severity and cognitive function, and assessments were performed by a neurologist and psychologist, within 10 days of stroke onset. Of the 23 patients, 21 (91.3%) had CASI scores below their respective cutoff values and all patients had cognitive impairment in at least one cognitive domain in CASI. There were no significant correlations between CASI abnormality (below the cutoff value) and patient age, education, or the interval from stroke onset. Recent memory impairment was the most often impaired cognitive domain on CASI (19 patients, 82.6%). There were significant correlations between recent memory and "attention or concentration"(correlation coefficient, 0.52; p < 0.05), and "abstraction and judgment" (correlation coefficient, 0.44; p < 0.05). The correlations between recent memory and other domains were not significant. It was concluded that cognitive impairment after acute lacunar infarct is quite common and recent memory is the most often impaired cognitive domain. This may have been caused by the location of the specific lesion as well as by the impairment in "attention or concentration" or "abstraction and judgment".

Acute Disease↗

PubMed2003

Different types of ground glass hepatocytes in chronic hepatitis B virus infection contain specific pre-S mutants that may induce endoplasmic reticulum stress.

Ground glass hepatocyte (GGH) represents a histological hallmark of chronic hepatitis B virus infection and contains surface antigens in the endoplasmic reticulum (ER). Several types of GGHs are recognized at different hepatitis B virus replicative stages. The recent identification of pre-S mutants from GGHs encourages us to investigate whether different GGHs may harbor specific mutants and exhibit differential biological activities. In this study, we applied laser capture microdissection to isolate specific GGHs from a total of 50 samples on eight resected liver specimens. The surface genes in two major types of GGHs were analyzed. Type I GGHs expressed an inclusion-like pattern of hepatitis B surface antigens and harbored mutants with deletions over pre-S1 region, whereas type II GGHs, distributed in clusters and emerged at late replicative phase, contained mutants with deletions over pre-S2 region that defines a cytotoxic T lymphocyte (CTL) immune epitope, and may represent an immune escape mutant. Transfection of pre-S mutants in Huh7 revealed decreased syntheses of middle and small S proteins with accumulation of large surface antigen in ER, which in turn led to the activation of ER stress response with differential activities for different mutants. This study therefore demonstrates that different GGHs may contain specific mutants and exhibit differential biological activities.

Cell Line↗