PubMed Health⌕ Search

Biomedical subjects

C T Wong

Publications and source records attributed to C T Wong.

At least 37 records · Page 2Linked to original sources
PubMed1994

Failure of Saccharomyces boulardii to hydrolyse bile acids in vitro.

The bile acid deconjugating capacity of Saccharomyces boulardii was tested in isolated culture and in co-culture upon the bile acid metabolizing capacity of Bacteroides fragilis. S. boulardii was grown over 60 h in plain brain heart infusion (BHI) broth and in the presence of either 2 mM glycocholic or glycochenodeoxycholic acid under both aerobic and anaerobic conditions. S. boulardii did not metabolize either glycocholic acid or glycochenodeoxycholic acid. S. boulardii and B. fragilis were grown anaerobically together in BHI broth supplemented with either 0.1 mM glycholic acid or 0.1 mM glycochenodeoxycholic acid. When S. boulardii and B. fragilis were anaerobically co-cultured, S. boulardii did not alter the bile acid metabolism of B. fragilis. Specifically primary and conjugated bile acids decreased over time, while keto bile acids and free bile acids increased. S. boulardii not only fails to metabolize primary conjugated bile acids but it does not enhance or inhibit the bile acid metabolism of B. fragilis when the organisms are co-cultured in anaerobic medium.

Bacteroides fragilis↗
PubMed1993

Abscess scintigraphy with 99mTc-human immunoglobulin (IgG) using a one-step labeling method.

It was shown earlier that non-specific human gamma globulin (IgG) labeled with 111In can be used as an agent for abscess localization. We describe experimental results with 99mTc-IgG in animals bearing abscesses and tumors using a one-step labeling method with 99mTc. We studied this compound in several animal models: mice bearing turpentine abscesses and subcutaneously transplanted sarcomas, in rats with turpentine or E. coli abscesses and intracerebrally implanted gliomas and in rabbits with E. coli or turpentine abscesses. Blood clearance was studied in dogs. It was found that the absolute concentration of 111In-IgG in abscess and tumor was higher than that of 99mTc-IgG. However, the abscess-to-tumor ratio was higher for 99mTc-IgG. The 99mTc-IgG images were of high quality and abscesses could be detected as early as 30 min post-injection (p.i.). It appears that 99mTc-IgG has many potential advantages over 111In-IgG because of better physical properties of 99mTc, simpler preparation, lower cost and greater availability and the possibility of using higher 99mTc doses.

Abscess↗
PubMed1993

Biodistribution of Sn-117m(4+)DTPA for palliative therapy of painful osseous metastases.

Tin-117 has certain physical characteristics (half-life of 13.6 days, low-energy-conversion electrons, gamma photon of 158.6 keV) that suggest that it may be a favorable agent for radionuclide therapy. It has been shown in animal models that Sn-117m in the chemical form Sn(4+)diethylenetriaminepentaacetic acid localizes selectively in bone. The authors therefore studied its whole-body distribution in 10 patients to obtain absorbed dose estimates for therapy. The results showed that more than 50% of the administered activity was absorbed in the bones of patients with metastatic carcinoma. Retention was determined primarily by radioactive decay. For adult men, the radiation absorbed dose estimate averaged 54.8 mGy/MBq (203 rad/mCi) to bone surfaces and 6.1 mGy/MBq (22.6 rad/mCi) to the red marrow. All other tissues received less than 1/10 of the dose received by red marrow. These results suggest that a clinical therapeutic trial should be attempted.

Adult↗
PubMed1993

SPECT and planar brain imaging in crack abuse: iodine-123-iodoamphetamine uptake and localization.

The uptake, distribution, and clearance properties of 123I-IMP in the brain were evaluated in controls and asymptomatic crack users to investigate cerebral blood flow alterations in crack abuse. Serial dynamic planar images of the brain (0-25 min), SPECT of the brain (0.5 hr and 4 hr) and whole-body scans (75 min) were obtained in 21 crack abusers and 21 control subjects. Major observations include: (a) foci of abnormally reduced 123I-IMP activity mainly in the frontal and parieto-occipital cortex or marked irregularities in the uptake of 123I-IMP throughout the cerebral cortex consistent with moderate to severe disruption in regional cerebral blood flow were observed on the 0.5 hr SPECT images of 16/21 asymptomatic crack users; (b) no correlation could be demonstrated between the incidence or severity of SPECT perfusion abnormality with the frequency, amount or length of time of crack use; (c) focal perfusion defects observed in 6/21 crack users on the 0.5-hr SPECT images partially or completely filled-in on delayed SPECT at 4 hr in four of six subjects; (d) the rate of cerebral uptake of 123I-IMP in crack users averaged 23% less than observed in control subjects over the first 25 min after tracer administration; and (e) 123I-IMP activity reaching the brain of cigarette smoking control subjects (n = 14) at 25 min after injection averaged 42.5% less than in nonsmoking controls (n = 7). Quantitative measurements of the uptake and distribution properties of 123I-IMP in the brain proved to be an objective, sensitive and useful measure of regional cerebral blood flow in crack abuse.

Adult↗
PubMed1991

Lack of influence of maternal and fetal transferrin phenotypes and concentrations on normal fetal growth.

Influence of maternal and fetal transferrin types and concentrations on the fetal growth has been investigated in 1,174 normal full-term singleton newborns, including 352 mother-newborn pairs. No significant effect of these parameters was observed on the weight and length of the newborns. Newborn plasma transferrin concentration was not correlated with maternal plasma transferrin concentration.

Birth Weight↗
PubMed1990

Changes in serum proteins (albumin, immunoglobulins and acute phase proteins) in pulmonary tuberculosis during therapy.

Serum levels of three immunoglobulins (IgG, IgA & IgM), albumin and six acute phase proteins (alpha 1-antitrypsin, haptoglobin, transferrin, alpha 2-macroglobulin, complements C3 & C4) were measured by immunoelectrophoresis in 57 patients with pulmonary tuberculosis when they were first diagnosed, and followed at 1 month, 2 month and 4 month intervals during anti-tuberculosis treatment. These values were compared to those from 41 healthy controls. Significant increases were observed in the initial values of serum IgG, IgM, alpha 1-antitrypsin and haptoglobin, while transferrin and alpha 2-macroglobulin levels were significantly reduced. No changes were observed in the levels of serum albumin, IgA and complement C3. Levels of all measured proteins decreased with treatment. However, at 4 months, IgG and alpha 1-antitrypsin were still significantly elevated when compared to control values, while the level of haptoglobin had decreased to a level significantly lower than that of the control value.

Acute-Phase Proteins↗
PubMed1990

Inter-relationships of storage iron in the mother, the placenta and the newborn.

The influence of maternal storage iron and placental iron levels on the storage iron and serum transferrin levels in newborns, placental non-haem iron, serum ferritin and transferrin concentrations was studied in 72 mothers and their singleton healthy newborns following uncomplicated pregnancies. Serum ferritin and transferrin concentrations were measured using ELIZA and immunoelectrophoretic methods, respectively. Placental non-haem iron was measured chemically. Cord serum ferritin (142 +/- 68.6 micrograms/l) and transferrin (1.66 +/- 0.56 g/l) levels and placental non-haem iron concentrations (41.1 +/- 20.2 micrograms/g) were not correlated with the maternal serum ferritin levels (17.4 +/- 12.5 micrograms/l). No significant difference was observed in these parameters in the newborns of mothers with low (less than 10 micrograms/l) and high (greater than 20 micrograms/l) levels of serum ferritin. Thus mothers with a reduced store of iron at term can still manage to provide sufficient iron for the fetus.

Adult↗
PubMed1989

Serum immunoglobulin and acute phase protein concentrations in pulmonary tuberculosis patients in Singapore.

The levels of three immunoglobulins (IgG, IgA and IgM), albumin and five acute phase proteins (alpha 1-antitrypsin, haptoglobin, transferrin, alpha 2-macroglobulin and complement 3) were measured by immunoelectrophoresis in the sera of 33 Chinese male patients soon after they were diagnosed to be suffering from pulmonary tuberculosis. These values were compared to those in 41 healthy male controls. Significant increases were observed for IgG and alpha 1-antitrypsin (both p less than 0.001) and haptoglobin and IgM (both p less than 0.01) levels while transferrin and alpha 2-macroglobulin levels were significantly reduced (both p less than 0.02). The results suggest that these changes of plasma protein levels in pulmonary tuberculosis patients may be the result of humoral responses against tubercular antigens.

Acute-Phase Proteins↗
PubMed1987

Effect of iron chelators on placental uptake and transfer of iron in rat.

The uptake of radiolabelled transferrin and iron by the rat placenta has been studied using two approaches. The first involved injection of a ferrous or ferric iron chelator followed by injection of label. Neither chelator decreased the amount of labelled transferrin in the placenta after 2-h incubation and only bipyridine, a ferrous iron chelator, inhibited iron transport to the fetus. Deferoxamine (DFO), a ferric iron chelator, had no effect on iron transport to the fetus but reduced iron uptake by the liver. Both bipyridine and DFO increased iron excretion into the gut and by the urinary tract to the same degree into the gut, but there was a 10-fold greater urinary excretion with bipyridine than with DFO. Injection of iron attached to the chelators showed that neither bipyridine nor DFO could donate iron to the fetus as efficiently as transferrin. The mechanism involved was further investigated by studying the effect of the chelators on uptake of transferrin-bound iron by placental cells in culture. DFO inhibited iron accumulation more effectively than bipyridine in the cultured cells. The effect was not due to a decrease in the cycling time of the receptor. The results can be explained if the iron is released from the transferrin in intracellular vesicles in the ferrous form, where it may be chelated by bipyridine and prevented from passing to the fetus or converted to the ferric form once it is inside the cell matrix.

2,2'-Dipyridyl↗
PubMed1987

Haemoglobin, serum iron, transferrin, ferritin concentrations and total iron-binding capacity in erythrocyte glucose-6-phosphate dehydrogenase deficiency.

Erythrocyte deficiency may lead to shortened erythrocyte life-span and also influence iron metabolic processes. Haemoglobin, serum iron, transferrin and ferritin concentrations and total iron-binding capacity (TIBC) were compared in 74 normal and 68 glucose-6-phosphate dehydrogenase (G6PD) deficient subjects to investigate this possibility. All the parameters were measured using standard biochemical and immunoelectrophoretic methods. Haemoglobin and serum iron concentrations were similar in both groups of subjects. It was found that G6PD deficient subjects had significantly greater transferrin (P less than 0.001), ferritin (P less than 0.001) and TIBC (P less than 0.01) values compared to normal subjects. Some possible causes of these observations are discussed.

Adult↗
PubMed1986

Effects of transferrin genetic phenotypes on total iron-binding capacity.

Serum transferrin level and total iron-binding capacity (TIBC) were studied in a group of 297 healthy adult male subjects having HbAA and G6PDB+ phenotypes by standard chemical and immunoelectrophoretic techniques to examine the influence of different transferrin variants on these parameters. TIBC (67.1 +/- 13.4 mumol/l) and transferrin concentrations (27.0 +/- 3.95 mumol/l) for the whole group were found to be within reported normal values. Serum transferrin concentrations of the subjects having different electrophoretic variants and TfC subtypes of transferrin were not significantly different from each other. There was no significant difference of TIBC in relation to different electrophoretic variants of Tf. However, the TIBC of the subjects of the 1-1 subtype of TfC (70.4 +/- 13.6 mumol/l) was significantly higher than that of the 2-1 subtype (65.0 +/- 12.8 mumol/l; p less than 0.05) as well as that of the 2-2 subtype (60.4 +/- 11.4 mumol/l; p less than 0.01).

Adult↗
PubMed1985

Hepatic storage of iron and ferritin in different ethnic groups in Singapore.

The concentrations of non-haem iron, ferritin and ferritin-iron were measured in the livers of 137 adults and children collected at necropsy. The concentrations of non-haem and ferritin iron were found to be 146.6 +/- 95.2 micrograms/g and 61.6 +/- 32.4 micrograms/g, respectively, in males and 108.0 +/- 61.7 micrograms/g and 60.6 +/- 26.4 micrograms/g, respectively, in females. The values for males in Singapore were lower than those reported in developed Western countries. No correlation was observed between storage iron and age, or ferritin concentration and age. Concentrations of non-haem iron and ferritin were similar for persons dying from accident and coronary heart disease. The non-haem iron concentration in Chinese (187.9 +/- 101.0 micrograms/g) was significantly greater than that in Indians (103.1 +/- 65.8 micrograms/g), while the ferritin concentration in Chinese (6.18 +/- 2.37 mg/g) was significantly greater than either Malays (3.81 +/- 1.8 mg/g) or Indians (3.52 +/- 1.6 mg/g). A significant positive correlation was observed between the non-haem iron and ferritin and also ferritin-iron in Chinese males (r values of 0.678 and 0.598, respectively) and Indian males (r values of 0.576 and 0.612, respectively). However, the correlation between these indices was not significant in the case of Malay males. In premenopausal women the non-haem iron correlated well with ferritin (r = 0.737) and ferritin iron (r = 0.826) while the correlation was lacking in postmenopausal women.

Adolescent↗
PubMed1984

Serum transferrin concentrations and total iron-binding capacities in relation to different haemoglobin phenotypes.

Serum transferrin concentrations and total iron-binding capacities were measured in 184 adult male subjects using standard biochemical methods. The haemoglobin phenotypes of these subjects were also established. Decreases in both of these parameters were observed when HbAE, beta-thalassaemia trait (raised level of HbA2), and HbEE subjects were compared to HbA subjects. Though the decrease was slight in the cases of HbAE and beta-thalassaemia trait, HbEE subjects had significantly reduced values. Both the parameters were also significantly reduced when values from HbEE subjects were compared to those from HbAE and beta-thalassaemia trait. It is suggested that marginal liver damage is present in subjects with homozygous HbE, leading to a reduction in transferrin production.

Hemoglobin A↗