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B K Tan

Publications and source records attributed to B K Tan.

81 records · Page 5Linked to original sources
PubMed1976

Huntington's chorea. A random process.

The purpose of the present study was to investigate statistically the irregular nature of the choreatic jerks in Huntington's Chorea. EMG-bursts of certain muscles in a patient with Huntington's Chorea were taken as a measure of the jerks. Statistical analysis of the measurements, i.e. durations of bursts and intervals between bursts, revealed that the irregular nature of the choreatic jerks originate from a random process. Each choreatic jerk appears to be an entirely independent and unpredictable event.

Buttocks↗
PubMedDate not supplied

Cytochrome P450 content and ultrastructural changes in liver of zinc-treated C57/6J mice.

In a previous report, we have demonstrated that acute zinc administration reduced the hepatic cytochrome P450 content in female C57/6J mice. In this extended toxicological study, we investigated the effects of zinc administration on (a) the hepatic cytochrome P450 content of both male and female mice to evaluate whether the sex of the animal had any influence on the zinc effects and (b) the hepatocytes at the ultrastructural level. Two doses of zinc chloride at 28 micrograms g-1 body weight (equivalent to LD50 in chronic treatment) were administered intraperitoneally to male and female C57/6J mice at 24 h intervals. Significant reduction of hepatic cytochrome P450 content was observed to occur the next day in both acutely treated male and female mice. On examination under transmission electron microscopy, evidence was found of toxic injury to the hepatocytes of mice livers in the zinc-treated group. Glutathione-monochlorobimane adduct formation (which is specifically catalysed by glutathione transferase) was found to be depressed in Chang liver cells. The findings indicate that acute zinc administration reduced the hepatic cytochrome P450 content in C57/6J mice irrespective of gender.

Animals↗
PubMedDate not supplied

Antihyperglycaemic and anti-oxidant properties of Andrographis paniculata in normal and diabetic rats.

1. Oxidative stress is believed to be a pathogenetic factor in the development of diabetic complications. In the present study, we investigated the ethanolic extract of the aerial parts of Andrographis paniculata for antihyperglycaemic and anti-oxidant effects in normal and streptozotocin-induced type I diabetic rats. 2. Normal and diabetic rats were randomly divided into groups and treated orally by gavage with vehicle (distilled water), metformin (500 mg/kg bodyweight) or the extract (400 mg/kg bodyweight), twice a day for 14 days. 3. At the end of the 14 day period, the extract, like metformin, significantly increased bodyweight (P < 0.01) and reduced fasting serum glucose in diabetic rats (P < 0.001) when compared with vehicle, but had no effect on bodyweight and serum glucose in normal rats. Levels of liver and kidney thiobarbituric acid-reactive substances (TBARS) were significantly increased (P < 0.0001, P < 0.01, respectively), while liver glutathione (GSH) concentrations were significantly decreased (P < 0.005) in vehicle-treated diabetic rats. Liver and kidney TBARS levels were significantly lower (P < 0.0001, P < 0.005, respectively), whereas liver GSH concentrations were significantly higher (P < 0.05) in extract- and metformin-treated diabetic rats compared with vehicle-treated diabetic rats. Andrographis paniculata significantly decreased kidney TBARS level (P < 0.005) in normal rats. Hepatic superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities were significantly lower in vehicle-treated diabetic rats compared with vehicle-treated normal rats. The extract, as well as metformin, significantly increased the activity of SOD and CAT, but had no significant effect on GSH-Px activity in diabetic rats. The extract and metformin did not produce significant changes in the activity of these anti-oxidant enzymes in normal rats. 4. Our results show that oxidative stress is evident in streptozotocin-diabetic rats and indicate that the ethanolic extract of A. paniculata not only possesses an antihyperglycaemic property, but may also reduce oxidative stress in diabetic rats.

Animals↗
PubMedDate not supplied

Metallothionein expression and zinc levels in invasive ductal breast carcinoma.

Metallothioneins (MTs) and zinc are both known to promote progression of tumors in human cancers. A close relationship exists between MT and zinc, as synthesis of the former has been reported to be induced by the latter. To assess the relationship between MT and zinc content in breast cancer tissues, we analysed MT expression by immunohistochemistry and tissue zinc levels by atomic absorption spectrometry (AAS) in invasive ductal breast cancers and adjacent benign breast tissues. We observed overexpression of MT in breast cancer tissues and noted that zinc content in breast cancer tissues was twice that of benign breast tissues. The nuclear fraction obtained by subcellular fractionation of breast cancer tissues was found to have a higher zinc content than the plasma membrane and cytosolic fractions. Contrary to expectations, we found a significant inverse correlation of MT expression with zinc levels in breast cancer tissues, suggesting that whilst both synergistically influence growth and survival of tumor cells, they may also have divergent roles in carcinogenesis.

Breast↗