Biomedical subjects

P H Chang

Publications and source records attributed to P H Chang.

At least 19 recordsLinked to original sources

PubMed2004

Treatment of non-biodegradable wastewater by electro-Fenton method.

A novel electro-Fenton method, called the Fered-Fenton method, applying H2O2 and electrogenerated ferrous ions for treating organic-containing wastewater was investigated. By combining electrochemical reduction and chemical oxidation, the process can regenerate ferrous ions and remove organic compounds simultaneously in a batch reactor. Because the generation rate of ferrous ions is one of the key parameters in evaluating the oxidation efficiency of the reaction system, the initial current efficiencies (eta(i)) for iron (III) reduction are examined first. It shows that increasing initial ferric ion concentration can achieve high initial current efficiency. In addition, eta(i) decreased (ca. 20-100%) with increasing current density of cathode (ca. 40-199 A/m2). For illustration, the wastewater from chemical (i.e. electroless) nickel plating was treated in this investigation owing to its non-biodegradability and high organic concentration. The average pH, COD and Ni concentrations of this wastewater were about 5.0, 30,000 and 2,000 mg/L, respectively. Experimental results indicate that traditional Fenton method only removed 60% of COD when using 5,000 mg/L of ferrous ions. However, the COD removal efficiency was promoted after the electricity was introduced into the system (i.e. Fered-Fenton method). Moreover, Ni concentration was reduced from 2,080 to 0.3 mg/L, indicating that the removal efficiency was higher than 99.9%.

Electrochemistry↗

PubMed2001

Alcohol withdrawal.

Alcohol withdrawal syndrome is a significant cause of perioperative morbidity and mortality. Physicians should be able to: (1) identify high-risk patients preoperatively by using the various screening tests, (2) recognize patterns with AWS, and (3) use the appropriate supportive, behavioral, nutritional and pharmacological treatment.

Alcohol Withdrawal Delirium↗

PubMed2001

Hydatidosis in a Chapman's zebra (Equus burchelli antiquorum).

A 14-year-old male Chapman's zebra had been treated for a cervical granulomatous cellulitis for 3 months prior to sudden death associated with myocardial fibrosis. Incidental findings at necropsy included multiple 3-8-cm unilocular cysts in the liver and lungs. Cysts contained either a clear fluid with or without hydatid sand or a gelatinous substance with foci of mineralization. Light and scanning electron microscopic examination of the hydatid sand revealed free protoscolices as well as intact and ruptured brood capsules with protoscolices attached to the germinal membrane. The protoscolices had 2 rows of 36-38 rostellar hooks with a length of 25-30 microm. The cyst wall consisted of inner germinal, intermediate laminated, and outer adventitial layers. Hydatidosis caused by Echinococcus granulosus was diagnosed based on the unilocular cysts, multiple protoscolices formed in a brood capsule, typical trilayered cyst wall, and herbivorous intermediate host. This is the first reported case of animal hydatidosis in Taiwan. The infection is thought to have been established 12 years ago in South Africa prior to importation.

Animals↗

PubMed2001

A peritoneal mesothelioma in a captive aardwolf (Proteles cristatus).

A 10-year-old male aardwolf (Proteles cristatus) was presented abdominal distention and emaciation for 3 months. Physical examination revealed firm abdominal masses with effusions. Cytologic assessment of the effusion showed uniform round tumor cells with a surface brush border. Necropsy showed white velvety masses covering the peritoneal surface of the liver, gall bladder, stomach, omentum, mesentery, spleen, intestine, abdominal wall and diaphragm. Histologic examination demonstrated papillary projections, lined with cuboidal tumor cells supported by fibrous connective tissue cores, arising from the serosa of visceral organs. Cytoplasmic vacuolation and a surface brush border were evident on some cells under light microscopy. Tumor cells stained positive for both cytokeratin (AE1/AE3) and vimentin. Electron microscopy showed prominent surface microvilli, rough endoplasmic reticulum, mitochondria and desmosomes in tumor cells. This may be the first reported case of peritoneal mesothelioma in a captive wild aardwolf.

Animals↗

PubMed1996

Some considerations on the measurements of mean frequency shift and integrated backscatter following administration of Albunex.

Ultrasonic contrast agents have been of heightened interest in recent years. More success has been achieved by agents consisting of micro bubbles, since only a few of these agents are capable of producing very strong ultrasonic backscattered signals for the enhancement of certain tissue structures. Recent investigations also demonstrate that an analysis of the radio frequency (RF) backscattered echoes by the contrast agents may lead to quantitative means for assessing tissue perfusion. In these studies, a parameter, mean frequency shift (MFS) of the RF signal, along with integrated backscatter (IB) has received the most attention. In an effort to better understand the physical mechanisms responsible for the observed mean frequency shift, we have performed experiments on 10 dogs following injections of Albunex (Molecular Biosystems, Inc.) into the left atrium, coronary artery and abdominal aorta, respectively, for investigations in the heart and kidney. The integrated backscatter and mean frequency (MF) of a region of interest (ROI) were calculated from the RF signal acquired with a modified real-time ultrasonic scanner. The results show consistently that the RF signals acquired from all regions of interest are greatly affected by the presence of the contrast agent in the path between the transducer and the ROI, which can cause either an upward or a downward shift of the MF. This could not be observed by video densitometry or a measurement of the IB alone. The MFS is the result of the resonant behavior of the micro bubbles, which is related to the frequency, ambient pressure, and physical properties of the bubbles including size distribution, surface tension and concentration. On the other hand, when there is no contrast agent present in the path, a downward frequency shift is seen.

Albumins↗

PubMed1996

Quantitative measurements of second harmonic Doppler using ultrasound contrast agents.

Quantitative measurements of second harmonic and first harmonic Doppler were carried out using two ultrasound contrast agents, Albunex and FS069. The RMS amplitudes of the Doppler shift spectra were measured as a function of the concentration of the agents, frequency and transmitted acoustic pressure. The results showed that, for a given lot of contrast agent investigated, FS069 was able to produce higher levels of first and, especially, second harmonic signals compared to Albunex. Under the same experimental conditions, the RMS Doppler amplitude (RDA) of FS069 was 3.8 +/- 0.8 dB higher than Albunex at first harmonic and 12.6 +/- 0.8 dB higher at second harmonic. The ratio of the second harmonic to first harmonic RDA, which we called R2/R1, decreases at a rate of 7 dB/MHz for both agents with increasing frequency. The difference in the value of R2/R1 between FS069 and Albunex at any frequency was approximately 4.5 dB. R2/R1 was found to increase linearly as a function of the transmitted acoustic pressure for both agents. Simulations using the Rayleigh-Plesset equation show a decrease of R2/R1 at a rate of 5 dB/MHz. Comparison of experimental results with theory indicates that the shell elasticity parameter may be an increasing function of the mean diameter of the bubbles.

Albumins↗

PubMed1995

Insulin, but not estrogen, correlated with indexes of desaturase function in obese women.

This study determined the associations of serum insulin and estrogen with fatty acid composition, fatty acid product/substrate ratios used as indexes of desaturase enzyme function, and platelet aggregation in obese and lean women. Thirty women were classified as obese (n = 8) or lean (n = 21) based on body mass index. Obese women were characterized by higher insulin levels (p < 0.05) but fasting glucose levels did not differ (p > 0.05) from lean women. Insulin positively correlated with increased C20:4n6/C18:3n6 (index of delta 5-desaturase) (p < 0.05) and C20:4n6/C18:2n6 (index of overall n6 pathway activity) (p < 0.01) in serum, and the n5 pathway in platelets (p < 0.01), but there was no correlation for insulin with platelet C18:3n6/C18:2n6 (index of delta 6-desaturase activity). Insulin was also positively related (p < 0.01) to aggregation as measured by impedance and negatively related to lag time (p < 0.05). Platelets of obese women aggregated more (p < 0.05) compared to lean women and began aggregating faster (p < 0.05), suggesting the possibility that the obese women were at greater risk for enhanced blood clotting. Plasma estrogen was correlated with age (p < 0.05) but not for other variables studied (p > 0.05). Insulin, but not estrogen, appears to influence desaturase activity, as demonstrated by increased desaturase function associated with hyperinsulinemia in obese women.

Adult↗

PubMed1991

Synergy between preactivated photofrin-II and tamoxifen in killing retrofibroma, pseudomyxoma and breast cancer cells.

Exposure of photoactive compounds to light prior to their use in biological systems (preactivation) results in the generation of tumour cell specific metastable cytotoxic species that are no longer dependent on the light energy. Thus, preactivation renders the photoactive compounds suitable for systemic use. We have examined the in vitro effect of preactivated photofrin-II and tamoxifen in retroperitoneal fibroma, pseudomyxoma and male breast carcinoma cell lines. These cells were found to be non-responsive to tamoxifen and were negative for oestrogen receptors. Incubation of these cells with 0.5 microgram/ml preactivated photofrin-II and tamoxifen (less than 10(-6) mol/l) resulted in a significantly enhanced (P less than 0.001) inhibition of DNA synthesis compared with either agent alone. This synergistic effect between tamoxifen and preactivated photofrin-II was determined by multiple drug effect analysis. Treatment of cells with preactivated photofrin-II did not cause the increased expression of oestrogen receptors. These observations suggest that a combination of antihormonal drugs with preactivated compounds may be of clinical value.

Breast Neoplasms↗

PubMed1988

Morphometric analysis of epithelial cells of frog urinary bladder, II. Effect of ADH, calcium ionophore (A23187) and verapamil on isolated dissociated cells.

Isolated frog urinary bladder epithelial cells, upon dissociation lose their polarity and develop microridges and occasional microvilli in a global fashion. These cells, when exposed only to isotonic Ringer's solution manifest a membrane conformation with smooth discontinuous microridges, a cytoplasm with numerous free ribosomes, rough ER, thin Golgi cisternae, mitochondria, small vacuoles, electron-dense granules, few microtubules, and numerous microfilaments and intermediate filaments with an apparent random distribution, the dissociated cells, when treated with ADH or calcium ionophore (A23187), have the appearance of numerous elongated microvilli over the entire cell surface. The cytoplasm, under these conditions, is occupied by large vacuoles with a distribution of long profiles of aggrephores and associated vesicles. The peripheral cytoplasm as well as the cavities of the elongated microvilli of these cells contain large concentrations of microfilaments often showing a strong axial orientation to the long axis of the microvilli. Many of these filamentous elements appear in contact with the apical membrane of these microvilli with an alignment with the external glycocalyx. There is an indication that these morphocytological changes as revealed by SEM and TEM studies, correlated with a redistribution and realignment of microfilaments and possibly microtubules as detected by fluorescent microscopy using immunofluorescent antibody labeling for actin and tubulin. Cells treated with verapamil, a calcium antagonist, presented dwarf and stout microvilli with little detectable alterations in the cytoplasmic compositions from that of non-hormonal treated cells. Verapamil prevented ADH induction of microvilli, with the membrane, under these conditions, appearing as compact microridges. The results indicate that calcium ionophore, like ADH, produces intense formation of microvilli in dissociated cells, mobilization and realignment of microfilaments, microtubules, increase in the density of vesicles, aggrephores and possibly secretory granules, whereas the calcium antagonist, verapamil, opposes these actions. The results suggests a prominent role of calcium in the morphological changes induced by ADH.

Animals↗

PubMed1985