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Biomedical subjects

C K Chang

Publications and source records attributed to C K Chang.

At least 55 records · Page 3Linked to original sources
PubMed2001

The cholesterolaemic effects of dietary fats in cholesteryl ester transfer protein transgenic mice.

In order to investigate the role of cholesteryl ester transfer protein (CETP) in the cholesterolaemic response to dietary fats, we analysed plasma lipid profiles of CETP-transgenic and control C57BL/6 mice fed standard chow (AIN-93G; AIN), a low-fat diet, and diets high in butter (saturated fatty acids; SFA), high-oleic acid safflower oil (monounsaturated fatty acids; MUFA), and safflower oil (polyunsaturated fatty acids; PUFA) for 5 weeks. Each group contained four or five mice. There were significant diet and dietxgenotype effects on plasma total cholesterol (TC; and respectively), liver TC ( and respectively), and esterified cholesterol (EC; and respectively); diet effects on plasma triacylglycerol liver free cholesterol and body weight a genotype effect on body-weight gain and a dietxgenotype effect on energy intake In transgenic mice the SFA diet caused significantly higher plasma TC than the PUFA diet In control mice MUFA and PUFA diets, but not the SFA diet, caused significantly higher plasma TC than the low-fat and AIN diets Transgenic mice fed PUFA had lower plasma TC while transgenic mice fed MUFA had lower LDL+VLDL-cholesterol than controls in the same dietary groups. Transgenic mice fed MUFA and PUFA diets also had significantly higher liver TC and respectively) and EC and respectively) than controls fed the same diets. In the present study we showed that: (1) CETP transgenic mice had a cholesterolaemic response to dietary fats similar to that in human subjects; (2) CETP transgenic mice fed PUFA showed significantly lower plasma TC, while those fed MUFA had lower LDL+VLDL-cholesterol than controls; (3) hepatic accumulation of cholesterol, possibly resulting from the combination of the enhanced cholesteryl ester transfer to apolipoprotein B-containing lipoproteins and increased hepatic uptake of cholesterol, may contribute to the cholesterol-lowering effect of MUFA and PUFA in CETP-transgenic mice; (4) CETP may play a role in appetite and/or energy regulation.

Animal Nutritional Physiological Phenomena↗
PubMed2001

The protective effect of hypervolemic hemodilution in experimental heatstroke.

The authors tested the hypothesis in a rat model that hypervolemic hemodilution during heatstroke affected the mean arterial pressure (MAP), striatal dopamine (DA) release, and local cerebral blood flow and neuronal damage score in different brain structures. The heatstroke was induced by exposing the urethane-anesthetized rats to an ambient temperature of 42 degrees C. Hypervolemic hemodilution was produced by intravenous administration of 10% human albumin. Relative and absolute blood flow in the corpus striatum were determined using the laser Doppler flowmetry and the autoradiography diffusible tracer technique, respectively. The DA release in the striatum was estimated using the in vivo microdialysis technique. After onset of heatstroke, animals with hypervolemic state alone, produced by saline or heparinized blood injection, displayed higher values of DA release, as well as neuronal damage score in the striatum, hypothalamus, or cortex, but lower values of MAP and blood flow in the striatum, hypothalamus, or cortex compared to normothermic controls. However, the heatstroke-induced arterial hypotension, cerebral ischemia, increased striatal DA overload, and increased neuronal damage score were attenuated by induction of both hypervolemic and hemodilution state with 10% albumin either before or after the onset of heatstroke. In addition, constant infusions of a vasopressor agent phenylephrine (2 microg kg(-1) min(-1)) after the onset of heatstroke failed to maintain appropriate levels of MAP and resulted in no protection against heatstroke. Thus, it appears that the observed benefit of the 10% albumin is secondary to hemodilution and/or maintenance of MAP.

Analysis of Variance↗
PubMed2001

A common precursor for the three subunits of L-glutamate oxidase encoded by gox gene from Streptomyces platensis NTU3304.

A segment of DNA containing the L-glutamate oxidase (gox) gene from Streptomyces platensis NTU3304 was cloned. The entire nucleotide sequence of the protein-coding portion consisting of 2130 bp (710 codons, including AUG and UGA) of the cloned DNA fragment was determined. The gox gene contained only one open reading frame (ORF) which coded for a 78-kDa polypeptide, the precursor of active extracellular Gox. Mature Gox is composed of three subunits, designated as alpha, beta, and gamma, with molecular masses of 39, 19, and 16 kDa, respectively. Analyses of the N-terminal amino acid sequences of the subunits revealed that the order of subunits in the precursor polypeptide encoded by the ORF, from N-terminus to C-terminus, is alpha-gamma-beta. The presence of the flavin adenine dinucleotide (FAD)-binding motif place Gox as a member of the flavoenzyme family. Furthermore, a negative effect of glucose on the biosynthesis of Gox was observed when it was used as carbon source.

Amino Acid Oxidoreductases↗
PubMed2001

Creation and utilization of a World Wide Web based space radiation effects code: SIREST.

In order for humans and electronics to fully and safely operate in the space environment, codes like HZETRN (High Charge and Energy Transport) must be included in any designer's toolbox for design evaluation with respect to radiation damage. Currently, spacecraft designers do not have easy access to accurate radiation codes like HZETRN to evaluate their design for radiation effects on humans and electronics. Today, the World Wide Web is sophisticated enough to support the entire HZETRN code and all of the associated pre and post processing tools. This package is called SIREST (Space Ionizing Radiation Effects and Shielding Tools). There are many advantages to SIREST. The most important advantage is the instant update capability of the web. Another major advantage is the modularity that the web imposes on the code. Right now, the major disadvantage of SIREST will be its modularity inside the designer's system. This mostly comes from the fact that a consistent interface between the designer and the computer system to evaluate the design is incomplete. This, however, is to be solved in the Intelligent Synthesis Environment (ISE) program currently being funded by NASA.

Algorithms↗
PubMed2000

Preparation and initial characterization of the compound I, II, and III states of iron methylchlorin-reconstituted horseradish peroxidase and myoglobin: models for key intermediates in iron chlorin enzymes.

To better understand the spectral properties of high valent and oxyferrous states in naturally occurring iron chlorin-containing proteins, we have prepared the oxoferryl compound I derivative of iron methylchlorin-reconstituted horseradish peroxidase (MeChl-HRP) and the compound II and oxyferrous compound III states of iron MeChl-reconstituted myoglobin. Initial spectral characterization has been carried out with UV-visible absorption and magnetic circular dichroism. In addition, the peroxidase activity of iron MeChl-HRP in pyrogallol oxidation has been found to be 40% of the rate for native HRP. Previous studies of oxoferryl chlorins have employed tetraphenylchlorins in organic solvents at low temperatures; stable oxyferrous chlorins have not been previously examined. The present study describes the compound I, II, and III states of histidine-ligated iron chlorins in a protein environment for the first time.

Animals↗
PubMed2000

Xanthene-bridged cofacial bisporphyrins.

The synthesis and characterization of cofacial bisporphyrins juxtaposed by xanthene-bridged pillars are presented. The one-pot preparation of the xanthene dialdehyde avoids the lengthy bridge synthesis accompanying other cofacial porphyrin systems, thus allowing for the facile preparation of homobimetallic zinc (10), copper (11), and nickel (12) complexes. The cofacial orientation of the two porphyrin macrocycles was confirmed by X-ray crystallography. Structural data are provided for bisporphyrins 10-12: 10 (C79H82N8OZn2), triclinic, space group P1, a = 11.2671(2) A, b = 14.9809(2) A, c = 20.4852(2) A, alpha = 101.6680(10) degrees, beta = 100.8890(10) degrees, gamma = 101.8060(10) degrees, Z = 2; 11 (C79H82N8OCu2), triclinic, space group P1, a = 11.21410(10) A, b = 14.9539(5) A, c = 20.6915(7) A, alpha = 101.810(2) degrees, beta = 101.044(2) degrees, gamma = 101.722(2) degrees, Z = 2; 12 (C79H82N8ONi2), monoclinic, space group C2/c, a = 24.1671(4) A, b = 10.669 A, c = 50.5080(9) A, beta = 99.553(2) degrees, Z = 8. Exciton interactions between the porphyrin rings are apparent in electronic spectra, consistent with the cofacial superstructure. The combination of structural and spectroscopic data provides a basis for the design of additional metal derivatives for the activation of dioxygen and other small molecules.

Bridged-Ring Compounds↗
PubMed2000

Superior vena cava thrombosis after in vitro fertilization: case report and review of the literature.

Ovarian hyperstimulation syndrome (OHSS) is a rare complication of fertility medication. A 33 year old female with OHSS with thrombosis of the right internal jugular vein, subclavian vein, and superior vein cava underwent in vitro fertilization following stimulation with a GnRH analog with successful implantation. The patient developed abdominal distention and dyspnea, with persistent symptoms that resulted in a 20 lb weight loss. As pregnancy progressed, edema, pain, and tingling sensations developed by the ninth week at which time a CT scan confirmed thrombus with the right internal jugular and subclavian vein and a free floating tip in the superior vena cava. Following treatment with intravenous heparin therapy and subcutaneous low-molecular weight heparin until delivery her symptoms improved. While optimal treatment remains unclear, treatment strategies remain conservative. Identifying the risk factors that lead to the development of OHSS including the identification of those patients at risk for developing OHSS, more extensive investigation of potential underlying coagulopathy in severe or recurrent cases, and consideration of prophylactic subcutaneous heparin or IV albumin supplementation, will facilitate prevention in the high risk population.

Adult↗
PubMed1999

The neuroprotective effect of DL-tetrahydropalmatine in rat heatstroke.

After the onset of heatstroke, rats with saline injection displayed hyperthermia, decreased mean arterial pressure, decreased cerebral blood flow, increased brain monoamine release, and increased neuronal damage score compared with those of normothermia, control rats. The heatstroke-induced hyperthermia, arterial hypotension, cerebral ischemia, brain monoamine overload, and cerebral neuronal injury were attenuated by pretreatment with dl-tetrahydropalmatine. The data indicate that DL-tetrahydropalmatine pretreatment provides neuroprotective effect in heatstroke.

Animals↗
PubMed1999

Inhibitory effect of dimethyl sulfoxide on nuclear factor-kappa B activation and intercellular adhesion molecule 1 gene expression in septic rats.

Antioxidants are potent radical scavengers that protect against endotoxemia and septic shock in animal models. Using a rat model of peritonitis sepsis induced by cecal incision we studied the effect of the free radical scavenger dimethyl sulfoxide (DMSO) on hepatic nuclear factor kappa B (NF-kappa B) activation, hepatic intercellular adhesion molecule 1 (ICAM-1) gene expression, serum tumor necrosis factor alpha (TNF) formation, and serum glucose concentration. Five groups of rats (N = 5) were treated as follows: (1) untreated control (Untreated), (2) sham operated with laparotomies (Sham), (3) pretreated with 6 ml/kg DMSO followed by sham operation (DMSO/Sham), (4) cecal incision (Sepsis), and (5) pretreated with DMSO followed by cecal incision (DMSO/Sepsis). In the DMSO/Sham group, DMSO did not affect NF-kappa B activation, ICAM-1 gene expression, and TNF formation. At 3 h postcecal incision, DMSO inhibited sepsis-induced hepatic NF-kappa B activation and hepatic ICAM-1 gene expression to control levels and suppressed serum TNF by 75%. In the late (6 h) septic phase, DMSO inhibited NF-kappa B activation (32%), ICAM-1 gene expression (27%), and TNF formation (71%). These findings suggest that the protective mechanism of antioxidants in septic rats may be partly due to the inhibition of NF-kappa B activation and NF-kappa B-mediated events.

Animals↗
PubMed1999

Sandwich enzyme-linked immunosorbent assay for plasma cholesteryl ester transfer protein concentration.

OBJECTIVES: Cholesteryl ester transfer protein (CETP) mediates the transfer of HDL cholesterol to apoB-containing lipoproteins. Its mass and activity are increased in several pro-atherogenic conditions. The objective of this study is to develop a cost- and time-effective sandwich ELISA for plasma CETP concentration. DESIGN AND METHODS: Monoclonal anti-CETP, TP20, was used as the capture antibody, while the other biotinylated monoclonal anti-CETP, TP2, was used for detection. The results were expressed in an arbitrary unit, ng biotin-TP2 bound per microl plasma. Plasma CETP concentrations, activities and their relationship were assessed in 35 IDDM children. RESULTS: The assay had an intra-assay CV of 8.75% and an inter-assay CV under 10%. Plasma CETP concentration of these subjects ranged from 0.36-1.89 ng biotin-TP2/microL. CETP concentration was significantly correlated with CETP activity (r = 0.51, p < 0.01). CONCLUSION: The sandwich ELISA we have developed carried sufficient sensitivity for assaying plasma CETP concentration in human.

Antibodies, Monoclonal↗
PubMed1999

Shielding from solar particle event exposures in deep space.

The physical composition and intensities of solar particle event exposures of sensitive astronaut tissues are examined under conditions approximating an astronaut in deep space. Response functions for conversion of particle fluence into dose and dose equivalent averaged over organ tissues are used to establish significant fluence levels and the expected dose and dose rates of the most important events from past observations. The BRYNTRN transport code is used to evaluate the local environment experienced by sensitive tissues and used to evaluate bioresponse models developed for use in tactical nuclear warfare. The present results will help to clarify the biophysical aspects of such exposure in the assessment of RBE and dose rate effects and their impact on design of protection systems for the astronauts. The use of polymers as shielding material in place of an equal mass of aluminum would provide a large safety factor without increasing the vehicle mass. This safety factor is sufficient to provide adequate protection if a factor of two larger event than has ever been observed in fact occurs during the mission.

Bone Marrow↗
PubMed1999

Successful surgical treatment of solitary adrenal metastases from non-small cell lung cancer: case report.

Lung cancer is one of the most common types of maligancies and has been one of the leading causes death due to cancer for a long time. Although surgery is the treatment of choice for patients with non-N2 localized disease, most of the lung cancer patients are found to have metastatic lesions at the same time as initial diagnosis. The median survival of patients with metastatic lung cancer is less than one year even when systemic chemotherapy is given. We present a patient with non-small cell lung cancer with no initial evidence of metastasis. He underwent curative resection of the primary tumor followed by local radiotherapy. Adrenal gland metastasis was found fours years after the first surgery. After surgical resection of this metastatic lesion, followed by adjuvant chemotherapy, this patient's survival was prolonged with no evidence of disease recurrence until now. The prolonged survival of this patient may be due to a slow rate of progression of the primary tumor.

Adrenal Gland Neoplasms↗
PubMed1998

Modification of superoxide dismutase (SOD) mRNA and activity by a transient hypoxic stress in cultured glial cells.

In order to understand the role of superoxide dismutase (SOD) in response to transient hypoxia or hypoxia-reperfusion in astrocytes, the present study performed an in vitro investigation using rat glial cells in culture. Hypoxia was induced by an incubation with nitrogen gas for 10 min and that followed a further reperfusion with air for 10 min was indicating as hypoxia-normoxia. Activity of SOD was determined by the reduction of nitroblue tetrazolium (NTB). Changes of mRNA for Cu,Zn-SOD or Mn-SOD were also characterized using Northern blotting analysis. Transient hypoxia increased the activity of Mn-SOD but not that of Cu,Zn-SOD in glial cells. Expression of mRNA for SOD was also elevated in cells received hypoxia and the mRNA level for Mn-SOD raised higher than that for Cu,Zn-SOD. In cells received hypoxia-reperfusion, these changes of SOD both the activity and the mRNA level were not observed. Otherwise, the SOD protein amount, both Cu,Zn-SOD and Mn-SOD, identified by Western blotting was not changed in glial cells receiving hypoxic stress or not. The obtained results suggest that gene expression and activity of Mn-SOD in glial cells can be activated in response to the transient hypoxic stress.

Animals↗
PubMed1998

Factors related to delayed treatment and posttreatment symptom severity in Taiwanese patients with benign prostatic hyperplasia.

We evaluated the sociodemographic and clinical factors of delayed treatment and posttreatment symptom severity in outpatients with benign prostatic hyperplasia (BPH). The study included 146 BPH patients treated at the National Taiwan University Hospital in early 1997. All patients were treated with alpha-adrenergic antagonists or finasteride for at least 2 weeks. A questionnaire based on Andersen's Health Behavior Model was used to assess various sociodemographic features, while the pre- and posttreatment symptoms severity was rated according to the International Prostate Symptom Score (IPSS). Multiple logistic regression was used to assess the associations of these factors with delayed treatment and posttreatment symptom severity. Subjects who had recently quit smoking or were blue-collar workers tended to delay treatment, while those who chose a medical center as the care provider for chronic diseases tended to be less likely to delay treatment. However, none of these associations were statistically significant. No enabling factors (income, insurance) or need factors (symptom scores) evaluated were associated with delayed treatment. Predisposing factors associated with higher posttreatment symptom severity were delayed treatment (over 12 months) (adjusted odds ratio [OR]: 2.67, 95% confidence interval [CI]: 1.16-6.16), quitting smoking (adjusted OR: 4.47, 95% CI: 1.34-14.94), and having never smoked (adjusted OR: 3.73, 95% CI: 1.15-12.11). Subjects with severe pretreatment symptoms were far more likely than subjects with mild pretreatment symptoms to have severe symptoms after treatment (adjusted OR: 52.69, 95% CI: 54.46-621.90). Our findings, though based on a limited number of subjects, suggest sociodemographic factors rather than objective clinical attributes (prostate specific antigen level, prostate volume, and urodynamic results) are associated with delayed treatment in Taiwanese men with BPH. Both pretreatment symptom severity and sociodemographic factors are related to posttreatment symptom severity.

Adult↗
PubMed1997

Activity-dependent regulation of NMDAR1 immunoreactivity in the developing visual cortex.

NMDA receptors have been implicated in activity-dependent synaptic plasticity in the developing visual cortex. We examined the distribution of immunocytochemically detectable NMDAR1 in visual cortex of cats and ferrets from late embryonic ages to adulthood. Cortical neurons are initially highly immunostained. This level declines gradually over development, with the notable exception of cortical layers 2/3, where levels of NMDAR1 immunostaining remain high into adulthood. Within layer 4, the decline in NMDAR1 immunostaining to adult levels coincides with the completion of ocular dominance column formation and the end of the critical period for layer 4. To determine whether NMDAR1 immunoreactivity is regulated by retinal activity, animals were dark-reared or retinal activity was completely blocked in one eye with tetrodotoxin (TTX). Dark-rearing does not cause detectable changes in NMDAR1 immunoreactivity. However, 2 weeks of monocular TTX administration decreases NMDAR1 immunoreactivity in layer 4 of the columns of the blocked eye. Thus, high levels of NMDAR1 immunostaining within the visual cortex are temporally correlated with ocular dominance column formation and developmental plasticity; the persistence of staining in layers 2/3 also correlates with the physiological plasticity present in these layers in the adult. In addition, visual experience is not required for the developmental changes in the laminar pattern of NMDAR1 levels, but the presence of high levels of NMDAR1 in layer 4 during the critical period does require retinal activity. These observations are consistent with a central role for NMDA receptors in promoting and ultimately limiting synaptic rearrangements in the developing neocortex.

Age Factors↗
PubMed1997

Changes of superoxide dismutase (SOD) mRNA and activity in response to hypoxic stress in cultured Wistar rat glioma cells.

In an attempt to understand the change of superoxide dismutase (SOD) in tumor cells by hypoxia and hypoxia-normoxia exposure, the present study performed an in vitro investigation using rat glioma cell line in culture. Hypoxia was induced by an incubation with nitrogen gas for 15 h followed the normoxia exposure with air for 30 min. Activity of SOD in cytosolic and particulate of cells was determined by the reduction of nitroblue tetrazolium. Changes of mRNA for Cu,Zn-SOD or Mn-SOD were also characterized using Northern blotting analysis. Hypoxic stress decreased the activity of SOD, both Cu,Zn-SOD and Mn-SOD, in glioma cells. Expression of mRNA for SOD was elevated by hypoxic stress and the increase of mRNA level for Cu,Zn-SOD was more marked than that for Mn-SOD. In response to hypoxia-normoxia exposure, an increase of activity with a lower mRNA level for Mn-SOD was observed in glioma cells. However, changes of Cu,Zn-SOD both the activity and the level of mRNA were not found in glioma cells by hypoxia-normoxia. The obtained results suggest that the SOD in glioma cells can be activated to compensate the damage from free radicals during hypoxic stress.

Animals↗
PubMed1997

Effect of dexamethasone on NF-kB activation, tumor necrosis factor formation, and glucose dyshomeostasis in septic rats.

Glucocorticoids are potent anti-inflammatory and immunosuppressive therapeutic agents. The protective effect of dexamethasone (DEX) on hepatic phosphoenolpyruvate carboxykinase (PEPCK) transcript level, hepatic NF-kB (nuclear factor-kB) activation, and serum tumor necrosis factor alpha (TNF) formation was investigated in peritoneal sepsis induced by cecal incision in rats. For the control the rats were sham-operated with laparotomies only. Each group (N = 6) was pretreated with either normal saline (NS) or DEX before surgery (NS/Sham, NS/Sepsis, DEX/Sham, and DEX/Sepsis). At 3 hr post cecal incision, DEX treatment inhibited sepsis-induced hepatic NF-kB activation by 23%, suppressed circulating TNF by 50%, reduced serum glucose by 36%, reduced hepatic glycogen depletion by 76%, and attenuated PEPCK mRNA level. These findings suggested that DEX treatment was beneficial in attenuating glucose dyshomeostasis and significantly inhibited two sepsis-induced inflammatory mediators, NF-kB and TNF, in the early phase of peritoneal sepsis. However, in the late (6 hr) septic phase, DEX treatment inhibited serum TNF by 69%, but had no effect on NF-kB activation, glycogen depletion, and PEPCK mRNA level suggesting liver function failure injury.

Animals↗