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Biomedical subjects

S T Chang

Publications and source records attributed to S T Chang.

At least 19 recordsLinked to original sources

Sudden death in Wolff-Parkinson-White syndrome combined with syncope: a case report.

Electrocardiogram showing Wolff-Parkinson-White (WPW) pattern in an asymptomatic patient is common, but it is difficult to assess the potential risk of sudden death in such cases. Although the incidence of sudden death in these patients is extremely low, an interventional approach is suggested for all patients despite its controversial nature. Syncope, despite being induced by various mechanisms, has been considered an alarming sign of sudden death of WPW syndrome. We describe a 16-year-old female patient with an electrocardiogram that demonstrated a WPW pattern combined with unexplained syncope. None of the examinations, including biochemical profiles, brain computed tomography, transthoracic echocardiography, head-up tilt table test and exercise electrocardiogram, clarified her syncope. Consequently, no further electrophysiologic study was performed for this patient. Unfortunately, the patient suffered sudden death while running. The case highlights the need for vigilance when unexplained syncope combined with WPW syndrome. Such cases have high risk of sudden death, and thus, further interventional study and treatment is indicated.

Adolescent↗

Clinical events occurrence and the changes of quality of life in chronic haemodialysis patients with dry weight determined by echocardiographic method.

The maintenance of circulating blood volume within an optimal range is necessary for haemodialysis patients to avoid circulating complications, including over-hydration and dehydration. Inferior vena cava diameter (IVCD) estimation is a non-invasive method to obtain a well correlation with the intravascular fluid status, and it may get a reliable ideal dry weight (DW) for chronic haemodialysis patients. We try to analysis the life quality changes and circulating complication in chronic haemodialysis patients who adjust DW with this tool in comparing with the traditional method. A total of 100 chronic haemodialysis patients, ranging from 26 to 77 years old, were involved in this study. They are randomly divided into study (n = 50) and control group (n= 50). All of them received the IVCD estimation by echocardiography every month for 3 months. The patients in the study group adjusted the DW with the IVCD estimated by echocardiographic method, however, patients in the control group with the traditional method. The quality of life (QOL) was evaluated with the short form 36 questionnaire (SF-36) in the beginning and the end of the study. The scores of physical functioning (PF), role limitation-physical (RP), general health (GH) and role limitation-emotional (RE) have much improvement in the patients of the study group than those in the control group. Besides, the occurrence of clinical events due to circulating complications during the study period showed significant reduction in the extents of hypotension, gastrointestinal upset, discontinuation of haemodialysis, muscular cramps, tinnitus, headache and chest discomforts with electrocardiographic changes; and these effects, especially, are significant in the patients with over-dehydrated status, which with the IVCD < 8 mm/m2 detected by echocardiographic method. The study demonstrated that ideal DW estimated by echocardiographic method not only improved the QOL but also reduced the circulating complications during haemodialysis for chronic haemodialysis patients.

Adult↗

Antibacterial activity of leaf essential oils and their constituents from Cinnamomum osmophloeum.

The antibacterial activities of the essential oils from leaves of two Cinnamomum osmophloeum clones (A and B) and their chemical constituents were investigated in this study. The nine strains of bacteria, including Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Salmonella sp., and Vibrio parahemolyticus, were used in the antibacterial tests. Results from the antibacterial tests demonstrated that the indigenous cinnamon B leaf essential oils had an excellent inhibitory effect. The MICs (minimum inhibitory concentrations) of the B leaf oil were 500 microg/ml against both K. pneumoniae and Salmonella sp. and 250 microg/ml against the other seven strains of bacteria. Cinnamaldehyde possessed the strongest antibacterial activity compared to the other constituents of the essential oils. The MICs of cinnamaldehyde against the E. coli, P. aeruginosa, E. faecalis, S. aureus, S. epidermidis, MRSA, K. pneumoniae, Salmonella sp., and V. parahemolyticus were 500, 1000, 250, 250, 250, 250, 1000, 500, and 250 microg/ml, respectively. These results suggest that C. osmophloeum leaf essential oil and cinnamaldehyde are beneficial to human health, having the potential to be used for medical purposes and to be utilized as anti-bacterial additives in making paper products.

Anti-Bacterial Agents↗

Soil biosensor for the detection of PAH toxicity using an immobilized recombinant bacterium and a biosurfactant.

A biosensor for detecting the toxicity of polycylic aromatic hydrocarbons (PAHs) contaminated soil has been successfully constructed using an immobilized recombinant bioluminescent bacterium, GC2 (lac::luxCDABE), which constitutively produces bioluminescence. The biosurfactant, rhamnolipids, was used to extract a model PAH, phenanthrene, and was found to enhance the bioavailability of phenanthrene via an increase in its rate of mass transfer from sorbed soil to the aqueous phase. The monitoring of phenanthrene toxicity was achieved through the measurement of the decrease in bioluminescence when a sample extracted with the biosurfactant was injected into the minibioreactor. The concentrations of phenanthrene in the aqueous phase were found to correlate well with the corresponding toxicity data obtained by using this toxicity biosensor. In addition, it was also found that the addition of glass beads to the agar media enhanced the stability of the immobilized cells. This biosensor system using a biosurfactant may be applied as an in-situ biosensor to detect the toxicity of hydrophobic contaminants in soils and for performance evaluation of PAH degradation in soils.

Biosensing Techniques↗

Antioxidant activity of extracts from Acacia confusa bark and heartwood.

The antioxidant activity of extracts from bark and heartwood of Acacia confusa was evaluated by various antioxidant assays, including free radical and superoxide radical scavenging assays and lipid peroxidation assay as well as hydroxyl radical-induced DNA strand scission assay. In addition, an ex vivo antioxidant assay using a flow cytometric technique was also employed in this study. The results indicate that both bark and heartwood extracts clearly have strong antioxidant effects. Similar inhibitory activities for each test sample were found for both 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical generation and lipid peroxidation. As for the superoxide radical scavenging activity, the heartwood extract was more effective than the bark extract. Furthermore, the heartwood extract protected PhiX174 supercoiled DNA against strand scission induced by ultraviolet photolysis of H2O2, and it reduced the amounts of intracellular hydrogen peroxide, a reactive oxygen species, when it was co-incubated with human promyelocytic leukemia (HL-60) cells under oxidative stress.

Acacia↗

Antitermitic activity of essential oils and components from Taiwania (Taiwania cryptomerioides).

Antitermitic activity of Taiwania (Taiwania cryptomerioides Hayata) against Coptotermes formosanus Shiraki was demonstrated in laboratory tests. Blocks of sapwood and heartwood from T. cryptomerioides exhibited antitermitic activity. Bioassays revealed that heartwood essential oil exhibited the highest antitermitic activity, followed by sapwood essential oil and then the n-C6H14 soluble fraction when tested at 10 mg/g. The order of termite mortality of three compounds purified from n-C6H14 soluble extracts of heartwood was cedrol > alpha-cadinol > ferruginol. The termite resistance of T. cryptomerioides wood can be attributed to the termiticidal activity of cedrol and alpha-cadinol.

Animals↗

Antimite activity of essential oils and their constituents from Taiwania cryptomerioides.

Antimite activity of essential oils and their components obtained from Taiwania cryptomerioides Hayata heartwood against Dermatophagoides pteronyssinus (Trouessart) and Dermatophagoides farinae Hughes was investigated in this study. Results from antimite tests demonstrated that the essential oil extracted from T. cryptomerioides heartwood had miticidal activity against D. pteronyssinus and D. farinae with a mortality of 67.0 and 36.7% at the dosage of 12.6 microg/cm2 after 48 h. Alpha-cadinol possessed the strongest antimite activity compared with other components of the T. cryptomeioides heartwood essential oil. The rectified mortalities of D. pteronyssinus and D. farinae were 100% for alpha-cadinol at the dosage of 6.3 microg/cm2. The order of antimite activity of four dominant constituents was alpha-cadinol > T-muurolol > ferruginol > T-cadinol. Paired Student's t-tests showed that there were significant differences between the rectified mortality of alpha-cadinol, T-muurolol, ferruginol and that of T-cadinol at the dosage of 6.3 microg/cm2 after 48 h.

Animals↗

Cytotoxicity of extractives from Taiwania cryptomerioides heartwood.

The cytotoxicity of the dominant lignans and sesquiterpenoids from Taiwania (Taiwania cryptomerioides Hayata) was investigated. Three human tumor cells including A-549 lung carcinoma. MCF-7 breast adenocarcinoma and HT-29 colon adenocarcinoma were selected to illustrate the structure-cytotoxicity relationships of Taiwania's dominant compounds. Taiwanin A, taiwanin E and dimethylmatairesinol exhibited significant cytotoxicity against three human tumor cells. Among them, taiwanin A possesses the strongest cytotoxic activity. In addition, the morphology-based evaluation, flow cytometric analysis, and DNA fragmentation assays demonstrated that the tumor cell death induced by taiwanin A was due to apoptosis.

Antineoplastic Agents, Phytogenic↗

A biosensor for the detection of gas toxicity using a recombinant bioluminescent bacterium.

A whole-cell biosensor was developed for the detection of gas toxicity using a recombinant bioluminescent Escherichia coli harboring a lac::luxCDABE fusion. Immobilization of the cells within LB agar has been done to maintain the activity of the microorganisms and to detect the toxicity of chemicals through the direct contact with gas. Benzene, known as a representative volatile organic compound, was chosen as a sample toxic gas to evaluate the performance of this biosensor based on the bioluminescent response. This biosensor showed a dose-dependent response, and was found to be reproducible. The immobilizing matrices of this biosensor were stored at 4 degrees C and were maintained for at least a month without any noticeable change in its activity. The optimal temperature for sensing was 37 degrees C. A small size of this sensor kit has been successfully fabricated, and found to be applicable as a disposable and portable biosensor to monitor the atmospheric environment of a workplace in which high concentrations of toxic gases could be discharged.

Benzene↗

Production and distribution of endoglucanase, cellobiohydrolase, and beta-glucosidase components of the cellulolytic system of Volvariella volvacea, the edible straw mushroom.

The edible straw mushroom, Volvariella volvacea, produces a multicomponent enzyme system consisting of endo-1,4-beta-glucanase, cellobiohydrolase, and beta-glucosidase for the conversion of cellulose to glucose. The highest levels of endoglucanase and cellobiohydrolase were recorded in cultures containing microcrystalline cellulose (Avicel) or filter paper, while lower but detectable levels of activity were also produced on carboxymethyl cellulose, cotton wool, xylitol, or salicin. Biochemical analyses of different culture fractions in cultures exhibiting peak enzyme production revealed that most of the endoglucase was present either in the culture filtrate (45.8% of the total) or associated with the insoluble pellet fraction remaining after centrifugation of homogenized mycelia (32.6%). Cellobiohydrolase exhibited a similar distribution pattern, with 58.9% of the total enzyme present in culture filtrates and 31.0% associated with the pellet fraction. Conversely, most beta-glucosidase activity (63.9% of the total) was present in extracts of fungal mycelia whereas only 9.4% was detected in culture filtrates. The endoglucanase and beta-glucosidase distribution patterns were confirmed by confocal laser scanning microscopy combined with immunolabelling. Endoglucanase was shown to be largely cell wall associated or located extracellularly, with the highest concentrations being present in a region 1 to 2 microm wide immediately adjacent to the outer surface of (and possibly including) the hyphal wall and extending 60 to 70 microm from the hyphal tip. Immunofluorescence patterns indicated little if any intracellular endoglucanase. Most beta-glucosidase was located intracellularly in the apical area extending 60 to 70 microm below the hyphal tip, although enzyme was also evident in the extracellular region extending approximately 15 microm all around the hyphal tip and trailing back along the length of the hypha. The regions of the hypha located some distance from the apical region appeared to be devoid of intracellular beta-glucosidase, and the enzyme appears to be associated almost exclusively with, or located on the outside surface of, the hyphal wall.

Journal Article↗

Neuronal supernumerary and dendritic sprouting of the nucleus ambiguus after chronic alteration of peripheral targets in cats.

Anatomic changes of neuronal profiles in response to chronic alteration of peripheral targets were investigated in the nucleus ambiguus (NA) of cats. Unilateral vagal-hypoglossal nerve anastomosis was performed by suturing the transected proximal stump of the vagus nerve to the transected distal stump of the hypoglossal nerve. After comparing horseradish peroxidase (HRP)-labeled neurons on the ipsilateral operated side of the NA with the contralateral unoperated NA and the NA following transection and reuniting to the vagus itself, a remarkable ramification and elongation of the dendritic trees was observed in the HRP-positive neurons on the ipsilateral NA. Quantitative analysis of neuronal profiles revealed that the number of the medium and large neurons on the ipsilateral NA was greater than the contralateral NA and the NA following autologous suturing of the vagus. Comparisons of variable dendritic lengths of the medium and large neurons on the ipsilateral NA revealed longer distances and more branches of the tertiary and perisomatic dendrites than those of the contralateral NA and the NA ipsilateral to autologous reunion. Our results suggest that remarkable sprouting and elongation of the dendritic trees as well as cell supernumerary occurred in the dominant NA motoneurons ipsilateral to the nerve anastomosis. In conclusion, there is a trophic influence in the tongue musculature, which was retrogradely transported to the NA neurons via the regenerating axons and caused the morphological changes in the NA in response to the rerouting of efferents from the vagus nerve to the hypoglossal nerve to innervate intimate tongue musculature.

Animals↗

Probing residue-level unfolding during lysozyme precipitation.

We have employed nuclear magnetic resonance (NMR) measurements of hydrogen exchange to identify residue-level conformational changes in hen egg white lysozyme (HEWL) as induced by salt precipitation. Deuterated HEWL was dissolved into a phosphate (H2O) buffer and precipitated at pH 2.1 upon addition of solid KSCN or (ND4)2SO4, allowing isotope labeling of unfolded regions. After 1 h, each precipitate was then dissolved at pH 3.8 to initiate refolding and preserve labeling and subsequently purified for NMR analysis. HEWL precipitated by 1.0 M KSCN exhibited increased hydrogen exchange at 14 residues out of 42 normally well-protected in the native state. Of the affected residues, 9 were situated in the beta-sheet/loop domain. A similar, though less extensive, effect was observed at 0.2 M KSCN. Precipitation by 1.2 M (ND4)2SO4 resulted in none of the changes detected with KSCN. The popularity of ammonium sulfate as a precipitant is thus supported by this observed preservation of structural integrity. KSCN, in comparison, produced partial unfolding of specific regions in HEWL due most likely to known preferential interactions between -SCN and proteins. The severity of unfolding increased with KSCN concentration such that, at 1.0 M KSCN, almost the entire beta-sheet/loop domain of HEWL was disrupted. Even so, a portion of the HEWL core encompassed by three alpha-helices remained intact, possibly facilitating precipitate dissolution.

Animals↗

Dexon and nylon-sutured wound reaction in conjunctival flap after trabeculectomy combined with or without topical application of mitomycin-C.

In this study, rabbits were used to evaluate the sutured wound reaction with Dexon or nylon in the conjunctival flap 1, 4, 7, 14 and 28 days after trabeculectomy surgery with or without the use of mitomycin-C. Four major treated groups were used to compare their wound healing reaction; group 1--nylon-suture and non-mitomycin treatment; group 2--nylon-suture and mitomycin treatment; group 3--Dexon-suture and non-mitomycin treatment; group 4--Dexon-suture and mitomycin treatment. One day after surgery, the number of polymorphs was the greatest most in the nylon-sutured and non-mitomycin treated tissues (86 +/- 2). Four days after surgery, the number of polymorphs was the greatest most in Dexon-sutured and non-mitomycin treated tissues (109 +/- 87). The number of fibroblasts was the greatest most in nylon-sutured and non-mitomycin treated tissues (111 +/- 23). Seven days after surgery, the number of polymorphs was the greatest most in Dexon-sutured and mitomycin treated tissues (32 +/- 12). The number of fibroblasts was the greatest most in nylon-sutured and non-mitomycin treated tissues (126 +/- 15). Fourteen days after surgery, the number of fibroblasts was the greatest most in Dexon-sutured and non-mitomycin tissues (43 +/- 10). The number of goblet cells was the greatest most in nylon-sutured and non-mitomycin treated tissues (4 +/- 2). Twenty-eight days after surgery, the number of fibroblasts was the greatest most in Dexon-sutured and mitomycin treated tissues (40 +/- 15). The number of goblet cells was the greatest most in nylon-sutured and non-mitomycin treated tissues (4 +/- 2). Our conclusions are as follows: 1). The concentration of mitomycin in conjunctival wound edge should be maintained at as low a level as possible because the mitomycin will delay the wound healing process; 2). Nylon material is better than Dexon for conjunctival wound suture because nylon could induce a great quantity of fibroblasts before Dexon did.

Administration, Topical↗

Free radical scavenging activities of mushroom polysaccharide extracts.

The superoxide and hydroxyl radical scavenging activities of eight mushroom antitumor polysaccharide extracts were investigated using phenazin methosulphate-NADH-nitroblue tetrazolium system and ascorbic acid-Cu(2+)-cytochrome C system respectively. The results showed that six of eight mushroom polysaccharide extracts had superoxide and hydroxyl radical scavenging activities. The protein content of the polysaccharide extracts appeared to contribute a direct effect on free radical scavenging activity. However, none of the mushroom polysaccharide extracts had antioxidative activity as measured by detecting malondialdehyde (MDA) contents of liver microsomes.

Antineoplastic Agents↗

Potentiation of sodium butyrate-induced apoptosis by vanadate in human promyelocytic leukemia cell line HL-60.

Vanadate (10 microM ), a potent inhibitor of tyrosine phosphatase, added simultaneously potentiated the sodium butyrate (BuONa)-induced growth inhibition. Furthermore, at 1 mM BuONa alone, after 96 h of incubation, about 20 +/- 5% of cells exhibited the morphological characteristic of apoptosis, as established by nuclear changes (condensed and fragmented nuclei) and decrease in cell size. After treatment of cells with 1 mM BuONa in the presence of 10 microM vanadate, apoptotic cells became more abundant; 90 +/- 3% of cells presented morphological characteristics of apoptosis after 96 h of incubation. Flow cytometric measurement of DNA content demonstrated the accumulation of cells in G1 phase after 72 h of incubation with 1 mM BuONa alone. In the presence of vanadate (10 microM ), accumulation of cells in G1 phase appeared after shorter times of incubation (48 h) with BuONa. A substantial increase in the proportion of cells with degraded DNA characteristic of apoptosis was observed after 48- to 72-h incubation with BuONa in the presence of vanadate. BuONa-induced apoptosis was accompanied by the increase of tyrosine phosphorylation of cellular proteins pp37 and pp97. Our results raised the possibility that regulation of tyrosine phosphorylation of pp37 and pp97 is an important event that heralds the BuONa-induced apoptosis.

Apoptosis↗

Induction in the mouse of gene expression of immunomodulating cytokines by mushroom polysaccharide-protein complexes.

Two antitumor polysaccharide-protein complexes, PSPC and PSK from mushrooms, were compared for their modulating effect on cytokine and cytokine receptor gene expression. RNA samples were isolated from the splenocytes and peritoneal exudate cells of the untreated or treated mice. Reverse transcription-polymerase chain reaction (RT-PCR) was used to analyze the cytokine gene expression. Nine out of 17 cytokine mRNAs and 5 out of 6 cytokine receptor mRNAs were detected in the splenocytes and peritoneal exudate cells from both untreated and treated mice. However, IL-4 was only detected in the splenocytes while IL-7 and IL-1R(typeI) were only detected in the peritoneal exudate cells. Among the 9 cytokine genes, the expression level of M-CSF was up-regulated in splenocytes and peritoneal exudate cells of the mice by PSPC and PSK. The expression level of TNF-alpha was only up-regulated in the peritoneal exudate cells by PSK, but not by PSPC.

Animals↗