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Biomedical subjects

S C Chiang

Publications and source records attributed to S C Chiang.

49 records · Page 3Linked to original sources
PubMed1980

Primary hepatocellular carcinoma developing in a female patient on long term oral contraceptives--a case report.

The association between hepatic tumours and oestrogen and progestogen therapy is well established. The risk of developing primary hepatocellular carcinoma (PHC) is small. In Africa and Asia where hepatitis B virus (HBV) infections are common, the development of PHC is also high. The presence of Hepatitis B core antibody indicates previous exposure to HBV and carries a risk of developing PHC by more than 34 times of non-infected normal. A Chinese female 29 years who had been on oral oestrogen and progestogen contraceptives continuously for 8 years developed PHC. She had no known illness due to HBV but was found to have concomitantly positive Hepatitis B core antibody in her sera. The presence of this HB core antibody and the long term consumption of oestrogen/progesterone derivatives may have been responsible for the early presentation of PHC in this patient. It is the first report in this country of PHC developing in a pill consumer since the introduction of oral contraceptives a decade ago In view of the prevalence of Hepatitis B in the region, this case finding warrants further study to determine whether (a) there is a higher frequency in pill consumers (b) an earlier age of presentation of hepatic malignancy. Meanwhile, it may be prudent to recommend alternative methods of birth control in individuals known to have been previously exposed to HBV infection, clinically or otherwise.

Adult↗
PubMed1977

Respiratory obstruction due to relapsing polychondritis in a Chinese male.

A case of relapsing polychondritis in a 30-year-old Chinese male is reported. The patient showed the following features: dyspnoea; hoarseness of voice; cauliflower deformity of the right ear; upper tracheal stenosis; swelling of the lower part of the sternum; pain in the costal cartilages. Airway obstruction as a presenting feature (as in this case) is unusual. The aetiology, clinical features and management of relapsing polychondritis are briefly discussed.

Adult↗
PubMed1977

A case of myasthenia gravis with thyrotoxicosis treated by combined subtotal thyroidectomy and total thymectomy.

Thyrotoxicosis occurring in conjunction with myasthenia gravis is rare. The usual treatment consists of medical control of the thyrotoxicosis, then thymectomy and later subtotal thyroidectomy. The case reported here concerns a 19-year-old girl who had surgical treatment for both lesions on the same occasion. With proper medical preparation, modern anaesthesia and respiratory care, the surgical treatment of both lesions can be accomplished in one stage.

Adult↗
PubMed1976

Copper and the oxidation of hemoglobin: a comparison of horse and human hemoglobins.

Oxidation studies of hemoglobin by Cu(II) indicate that for horse hemoglobin, up to a Cu(II)/heme molar ratio of 0.5, all of the Cu(II) added is used to rapidly oxidize the heme. On the other hand, most of the Cu(II) added to human hemoglobin at low Cu(II)/heme molar ratios is unable to oxidize the heme. Only at Cu(II)/heme molar ratios greater than 0.5 does the amount of oxidation per added Cu(II) approach that of horse hemoglobin. At the same time, binding studies indicate that human hemoglobin has an additional binding site involving one copper for every two hemes, which has a higher copper affinity than the single horse hemoglobin binding site. The Cu(II) oxidation of human hemoglobin is explained utilizing this additional binding site by a mechanism where a transfer of electrons cannot occur between the heme and the Cu(II) bound to the high affinity human binding site. The electron transfer must involve the Cu(II) bound to the lower affinity human hemoglobin binding site, which is similar to the only horse hemoglobin site. The involvement of beta-2 histidine in the binding of this additional copper is indicated by a comparison of the amino acid sequences of various hemoglobins which possess the additional site, with the amino acid sequences of hemoglobins which do not possess the additional site. Zn(II), Hg(II), and N-ethylmaleimide (NEM) are found to decrease the Cu(II) oxidation of hemoglobin. The sulfhydryl reagents, Hg(II) and NEM, produce a very dramatic decrease in the rate of oxidation, which can only be explained by an effect on the rate for the actual transfer of electrons between the Cu(II) and the Fe(II). The effect of Zn(II) is much smaller and can, for the most part, be explained by the increased oxygen affinity, which affects the ligand dissociation process that must precede the electron transfer process.

Animals↗
PubMedDate not supplied

Separation of porphyrins by capillary electrophoresis in fused-silica and ethylene vinyl acetate copolymer capillaries with visible absorbance detection.

A mixture of 5 porphyrins were separated by capillary electrophoresis. A UV-VIS detector was used to detect the separated components. Separation was performed in 2 types of capillaries, i.e. fused-silica and ethylene vinyl acetate copolymer (EVA) plastic capillaries. The concentration limit of detection (CLOD), mass limit of detection (MLOD), and relative standard deviations (RSD) of migration time and area were investigated. LOD was comparable to that of epi-fluorescence detection. LOD was lower when separation was performed in EVA capillary compared to fused-silica capillary. RSD of migration times of the porphyrins when separated in fused-silica capillary ranges between 0.5 to 1.6% and in EVA capillary ranges between 0.3 to 1.2%. Area RSD in fused-silica capillary ranges between 7 to 20% and in EVA capillary ranges between 4.7 to 12.3%. Urine spiked with porphyrins was also analysed by CE using fused-silica and EVA capillaries. Analysis of urine sample spiked with porphyrins showed that stacking effect of porphyrins was observable only in fused-silica and not in EVA capillary. This led to similar LOD in fused-silica capillary to those for EVA capillary.

Electrophoresis, Capillary↗
PubMedDate not supplied

Rapid detection of hog cholera virus in tissues by the polymerase chain reaction.

A rapid method for the detection of hog cholera virus (HCV) in infected tissues, using polymerase chain reaction (PCR) was developed. Total RNA isolated from HCV-infected tissues was reverse transcribed with AMV reverse transcriptase and the resulting complementary DNA was amplified by Taq DNA polymerase in the presence of two HCV-specific primers. The amplified DNA fragment was detected by agarose gel electrophoresis. The sensitivity of this method was at 10(4) TCID50 of HCV. The sensitivity increased approximately 1000-fold when the DNA was reamplified with a set of nested primers. DNA sequencing analysis of the PCR products revealed that the HCV sequence amplified from a local field isolate was highly homologous to the HCV Alfort strain. This method may be useful for pathological and epidemiological studies of HCV in pigs.

Animals↗
PubMedDate not supplied

Angular and rotational profile of the lower limb in 2,630 Chinese children.

Angular and rotational profile of the lower limbs of 2,630 normal Chinese children from newborn to age 12 years were compiled using tibiofemoral angle, intercondylar, intermalleolar distance, medial and lateral rotation of the hip, and thigh-foot angle. Children with clinical tibiofemoral angles, intercondylar or intermalleolar distances tended to be bowlegged at birth, maximally knock-kneed at age 3 and to have normal lower limbs by age 8. Medial hip rotation increased steadily from birth to a maximum of 56 degrees at age 9, and lateral hip rotation decreased from birth to a minimum of 30 degrees at age 9. Significant differences between Chinese children and children of other races were highlighted.

Ankle Joint↗
PubMedDate not supplied

Carnitine transport defect presenting with hyperammonemia: report of one case.

Carnitine (beta-hydroxy-gamma-trimethylaminobutyric acid) is involved in the transport of long-chain fatty acids into the mitochondrial matrix and removal of potentially toxic acylcarnitine esters. Carnitine transport defect is a very rare metabolic disease. A 7-month-old female infant was found to have consciousness disturbance, hyperammonemia, hepatomegaly and elevated transaminases. Both the concentrations of free carnitine and acylcarnitines in her blood were very low. The diagnosis of carnitine transport defect was confirmed by assays of carnitine uptake and transport in skin fibroblasts. She responded dramatically to carnitine therapy, and there was no hyperammonemia attack for more than 3 years. Her cardiac function also remained normal.

Ammonia↗