Biomedical subjects

S Y Chiou

Publications and source records attributed to S Y Chiou.

10 recordsLinked to original sources

PubMed2001

Optimizing production of polyunsaturated fatty acids in Marchantia polymorpha cell suspension culture.

Chlorophyll containing callus cells of Marchantia polymorpha are able to grow under dim illumination in the presence of an organic carbon source and retain the ability to produce polyunsaturated fatty acids (PUFA), including C(20) fatty acids. Highest PUFA production was achieved using 2,4-dichlorophenoxyacetic acid as growth regulator. Inoculum size, illumination intensity, organic carbon source, and ferrous ion are the major factors affecting PUFA productivity. Maximum PUFA productivity is attained under low light intensity, with a photon flux density ca. 20 micromol m(-2) s(-1). Optimal inoculum size and glucose concentration for PUFA production are 8-12% and 20-30 g l(-1), respectively. Ferrous ion can promote PUFA productivity by increasing the intracellular lipid content. Highest productivities for PUFA, arachidonic acid (ARA), and eicosapentaenoic acid (EPA) were 35.0+/-2.1, 6.7+/-0.4 and 6.6+/-0.4 mg l(-1) day(-1), respectively. PUFA production in the M. polymorpha culture is shown to be strongly growth-associated. Environmental stress (osmotic pressure) is ineffective in promoting PUFA productivity. Chitosan, an elicitor, also has no effect on intracellular PUFA content in cultured M. polymorpha cells.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2001

The triple-phase CT image appearance of post-irradiated livers.

OBJECTIVE: To evaluate the sequential CT appearance of the liver after hepatic irradiation and to investigate the correlation between CT findings and radiation-induced hepatic injury. MATERIAL AND METHODS: The triple-phase CT images of 18 patients with hepatocellular carcinomas (HCC) after hepatic irradiation were retrospectively reviewed (in total 41 CT studies). The high-dose region within the liver was defined as the area receiving more than 90% of the prescribed irradiation dose. The mean radiation dose was 55.5 Gy. Density changes and patterns of enhancement in the high-dose region were classified as three types: type I, constant low-density change in all phases; type II, low-density change in both pre-contrast and arterial phases, and iso-density change in the portal phase; type III, low- or iso-density change in the pre-contrast phase, low- or high-density change in the arterial phase, and persistent high-density change in the portal phase. The interval between completion of radiotherapy and the CT examinations ranged from 9 to 469 days, with a mean of 147 days. RESULTS: Nine of the 41 CT studies presented with type I, 9 with type II, and 16 with type III CT findings. The mean interval between completion of radiotherapy and the appearance of types I, II, and III CT findings were 74, 183, and 220 days, respectively. The interval was significantly shorter for type I findings than for type II and type III. The difference in interval was not significant between type II and type III. A type I finding with constant low-density change in the high-dose region of the liver was the most common pattern of CT findings within the first 3 months after hepatic irradiation. Either types II or III findings were frequently seen after 3 months. CONCLUSION: The sequential CT appearance and the density changes may indicate correlation with the pathogenesis of veno-occlusive disease.

Adult↗

PubMed2000

Quantitative structure-activity relationships for the pre-steady-state inhibition of cholesterol esterase by 4-nitrophenyl-N-substituted carbamates.

4-Nitrophenyl-N-substituted carbamates (1-6) are the pseudo-substrate inhibitors of porcine pancreatic cholesterol esterase. Thus, the first step of the inhibition (Ki step) is the formation of the enzyme inhibitor tetrahedral adduct and the second step of the inhibition (kc) is the formation of the carbamyl enzyme. The formation of the enzyme inhibitor tetrahedral adduct is further divided into two steps, the formation of the enzyme-inhibitor complex with the dissociation constant, KS, at the first step and the formation of the enzyme-inhibitor tetrahedral adduct from the complex at the second step. The two-step mechanism for the formation of the enzyme-inhibitor tetrahedral adduct is confirmed by the pre-steady-state kinetics. The results of quantitative structure-activity relationships for the pre-steady-state inhibitions of cholesterol esterase by carbamates 1-6 indicate that values of -logKs and logk2/k-2 are correlated with the Taft substituent constant, sigma*, and the rho* values from these correlations are -0.33 and 0.1, respectively. The negative rho* value for the -logKS-sigma*-correlation indicates that the first step of the two-step formation of the enzyme-inhibitor tetrahedral adduct (KS step) is the formation of the positive enzyme inhibitor complex. The positive rho* value for the logk2/k-2 -sigma*-correlation indicates that the enzyme inhibitor tetrahedral adduct is more negative than the enzyme inhibitor complex. Finally, the two-step mechanism for the formation of the enzyme inhibitor tetrahedral adduct is proposed according to these results. Thus, the partially positive charge is developed at nitrogen of carbamates 1-6 in the enzyme-inhibitor complex probably due to the hydrogen bonding between the lone pair of nitrogen of carbamates 1-6 and the amide hydrogen of the oxyanion hole of the enzyme. The second step of the two-step formation of the enzyme-inhibitor tetrahedral adduct is the nucleophilic attack of the serine of the enzyme to the carbonyl group of carbamates 1-6 in the enzyme-inhibitor complex and develops the negative-charged oxygen in the adduct.

Animals↗

PubMed1998

Topography of low skin resistance points (LSRP) in rats.

Based on the electrical properties of the skin, a method employing the unijunction transistor (UJT) relaxation oscillator for detecting low skin resistance points (LSRP) was developed in this study. By means of this instrumentation, the topography of the LSRP in Wistar rats was developed. All the LSRP in the rats were found to be bilaterally and symmetrically distributed except those points located on the dorsal midline (i.e., governor vessel, GV) and the ventral midline (i.e., conception vessel, CV). The resistances of the LSRP on these two major vessels, including 14 CV points and 17 GV points of six rats were experimentally determined to be in the ranges of 179.4 +/- 41.2 K omega and 152.5 +/- 32.2 K omega, respectively. The resistances of the GV points were found in general to be lower than those of the CV points. Most non-LSRP, on the other hand, exhibited resistances of greater than 420 K omega. It is noted that the resistances of most LSRP increased yet still retained a separate identity within thirty minutes after the death of the animals, but the low resistance properties of some LSRP gradually disappeared thereafter and could not be detected by the relaxation oscillator.

Acupuncture Points↗

PubMed1997

Inhibition of Japanese encephalitis virus infection by nitric oxide: antiviral effect of nitric oxide on RNA virus replication.

The antiviral effects of nitric oxide (NO) on Japanese encephalitis virus (JEV), a member of the family Flaviviridae, were investigated in this study. In vitro, inhibition of replication of JEV in gamma interferon-activated RAW 264.7 murine macrophages was correlated to cellular NO production. When cocultured with infected murine neuroblastoma N18 cells, gamma interferon-activated RAW 264.7 cells also efficiently hindered JEV replication in contiguous bystanders, and this anti-JEV effect could be reversed by an NO synthase (NOS) inhibitor, N-monomethyl-L-arginine acetate. In vivo, the mortality rate increased as the NOS activity of JEV-infected mice was inhibited by its competitive inhibitor, N-nitro-L-arginine methyl ester. Moreover, when an organic donor, S-nitro-N-acetylpenicillamine (SNAP), was used, the NO-mediated antiviral effect was also observed in primarily JEV-infected N18, human neuronal NT-2, and BHK-21 cells, as well as in persistently JEV-infected C2-2 cells. These data reaffirm that NO has an effective and broad-spectrum antimicrobial activity against diversified intracellular pathogens. Interestingly, the antiviral effect of NO was not enhanced by treatment of N18 cells with SNAP prior to JEV infection, a measure which has been shown to greatly increase the antiviral effect of NO in infection by vesicular stomatitis virus. From biochemical analysis of the impact of NO on JEV replication in cell culture, NO was found to profoundly inhibit viral RNA synthesis, viral protein accumulation, and virus release from infected cells. The results herein thus suggest that NO may play a crucial role in the innate immunity of the host to restrict the initial stage of JEV infection in the central nervous system.

Animals↗

PubMed1996

Effect of workers' shoe wear on objective and subjective assessment of slipperiness.

Subjective rating of slipperiness tests were conducted for 12 male industrial workers on three slippery surfaces, with poor or good lighting conditions, and with new or workers' own old shoes. A strain gauge force platform was used to evaluate dynamic coefficient of friction (COF) of shoes for the same surface conditions representing objective measurements. The shoe wear, available tread pattern, and hardness of old shoes were determined by instruments including a digital caliper, a digitizer, and a durometer, respectively. The surface effect was found to be highly significant on subjective ratings as well as dynamic COF (p < 0.0001). The correlation between dynamic COF values and subjective ratings was significant only for old shoes under medium oily conditions (r = 0.55, p < 0.04). For a slightly oily surface, decreasing the percent of tread available significantly increased dynamic COF values (p < 0.016). In addition, the effect of increased shoe hardness significantly increased the available tread pattern when only the data from the most deteriorated old shoes were included in the analyses (p < 0.004). These results emphasize the need to consider subjective assessment of slipperiness as a valid way to evaluate floor slipperiness. Further study is needed to (1) evaluate the effects of physical fatigue due to workload on subjective assessment of slipperiness and workers' ability to assess slipperiness during task performance; (2) consider the effect of available shoe tread on COF values and slip potential; and (3) determine if guidelines should be developed regarding when work shoes should be replaced to reduce slip and fall injuries.

Accidental Falls↗

PubMed1994

[Screening and rapid identification of Bacillus thuringiensis mutants].

Mutants of Bacillus thuringiensis subsp. kurstaki NTU 9 and Bt 158, which were isolated previously for using the diamondback moth as a target insect in Taiwan, were screening by either protein electrophoresis of intracellular proteins or enzyme-linked immunosorbent assay (ELISA). The optimal conditions of effective protein electrophoresis were (1) 24-hour cells harvested from nutrient broth were crashed by petite glass beads followed by centrifugation. And (2) the supernatant pretreated by heating at 60 degrees C for 2 minutes was electrophoresed with 7.5% native PAGE at 110 voltages. On ELISA, the antiserum used was obtained from rabbits immunized with Bt 158 crystal protein. Optimal antigen coating concentration of ELISA, attained by chequer-board titration method, was 10 micrograms/ml. Antigens (crystal protein) in samples were detected by competitive inhibition method with antiserum diluted to 10(4) fold. By using protein electrophoresis and ELISA methods, two isolates A 71 and BN 11, were denoted respectively as qualitative and quantitative mutants of Bacillus thuringiensis.

Animals↗

PubMed1992

Enterogenous cyst of the fourth ventricle: case report.

The authors present an intracranial enterogenous cyst of the fourth ventricle in a Chinese woman having symptoms of headache, dizziness and vertigo for approximately six months. A computerized tomography study of the brain disclosed a low density lesion within the fourth ventricle. A cystic tumor was completely removed and a histopathological examination diagnosed it is an enterogenous cyst; a rare lesion. During the post-operative follow-up, her symptoms gradually resolved and she was free of complaints within two years.

Brain Diseases↗

PubMed1990

Pituitary abscess-A case report.

Two hundred and five cases of pituitary lesion were treated in Tri-Service General Hospital up to March 1989. A case of pituitary abscess was diagnosed during operation. The primary clinical manifestations are consequent upon the pituitary dysfunction and the mass effect of the pituitary abscess. A pre-operative diagnosis of pituitary abscess is usually very difficult. Transsphenoidal drainage with an appropriate antibiotic coverage may provide an optimistic prognosis.

Abscess↗

PubMedDate not supplied

Peritoneal serous papillary carcinoma: a reappraisal of CT imaging features and literature review.

We evaluated the imaging features of primary serous peritoneal carcinoma (PSPC) on computed tomography (CT) and reviewed the literature. Preoperative CT images of 11 women with PSPC were retrospectively reviewed. The clinical presentations and serum levels of CA-125 were recorded. Special attention was paid to the operative and histopathologic findings of the ovaries. Imaging features were correlated with those in the literature. An elevation of serum CA-125 was found in 91% of cases. The CT findings included ascites (82%), peritoneal nodules or masses (73%), and omental nodules or omental caking (64%). Absence of an overt ovarian mass was observed in 64% of cases. The clinical manifestations and imaging features in our patients were consistent with those in the literature. Eighty-five percent of the ovaries in our study were superficially involved by PSPC in histopathologic examination. In none of our cases could the ovarian size be clearly assessed in the CT images. In conclusion, the presence of diffuse peritoneal disease and the absence of an ovarian mass on CT and an elevation of serum CA-125 level is suggestive of PSPC. However, in our experience, the evaluation of ovarian morphology and size by CT alone may not be as reliable.

CA-125 Antigen↗