Search PubMed⌕ Search

Biomedical subjects

K P Fung

Publications and source records attributed to K P Fung.

At least 19 recordsLinked to original sources
PubMed1993

Chemical syntheses of Trolox conjugates which protect human ventricular myocytes against in situ-generated oxyradicals.

Synthetic conjugates of the antioxidant Trolox (6-hydroxy-2,5,7,8-tetramethyl chroman-2-carboxylic acid) have been prepared by coupling it with 1-ethyl-3-(3-dimethyl-amino-propyl) carbodiimide hydrochloride either to p-aminophenyl-beta-D-lactopyranoside, or to higher molecular weight ligands such as dextran and polylysine. Compared to Trolox and on a mole to mole basis, dextran-Trolox is almost equally active, while lactosylphenyl- and polylysine-Trolox conjugates are distinctly more active in preventing the damage on human ventricular myocytes by oxyradicals generated from xanthine oxidase-hypoxanthine. Listed in order of decreasing cytoprotective activity, they are: lactosylphenyl-Trolox >> polylysine-Trolox > Trolox > dextran-Trolox. Thus, Trolox can be chemically modified by coupling it to one of a number of ligands and, in some cases, with resultant increases in its ability to protect human ventricular myocytes from oxyradical damage.

Antioxidants↗
PubMed1992

In vivo production of tumor necrosis factor for the treatment of mice bearing Ehrlich ascites tumor.

Tumor necrosis factor (TNF) was produced in mice bearing Ehrlich ascites tumor (EAT) by priming with zymosan and subsequently challenging with lipopolysaccharide. The optimal conditions for the in vivo production of TNF in treating EAT bearing mice were established. The endotoxin shock induced in mice during TNF production could be minimized by the combined administration of sulindac and mannoheptulose. The endogenous TNF produced could suppress proliferation of EAT cells as well as prolong the survival time of mice bearing small tumors.

Animals↗
PubMed1992

Mitogenic and tumor necrosis factor producing activities of Pseudostellaria heterophylla.

Separation of mitogenic fraction (PH-I) from Pseudostellaria heterophylla and characterization of its biological activities were investigated. PH-I was isolated as an alcohol-insoluble fraction from the hot water extract obtained by heating the roots of P. heterophylla in water at 80 degrees C for 4 h. It is a water-soluble substance consisting of mainly carbohydrates (56.8%) and a small amount of proteins (7.6%). The incorporation of tritiated thymidine into the DNA of murine spleen lymphocytes could be stimulated by PH-I in a dose-dependent manner. PH-I could act as a priming agent for the release of tumor necrosis factor (TNF) in mice. Moreover, PH-I exhibited potent anti-tumor activities against Ehrlich ascites tumor (EAT) cells in vivo but not in vitro.

Animals↗
PubMed1992

Midazolam as a sedative in esophageal manometry: a study of the effect on esophageal motility.

Midazolam 0.5 mg/kg was given intravenously as a sedative to 19 infants and children undergoing esophageal manometry after oral choral hydrate treatment. The lower esophageal sphincter pressure and motility were measured by manometry before and after midazolam injection. Midazolam did not change the lower esophageal sphincter pressure, blood pressure and respiratory rate of the subjects (p greater than 0.18), and the motility patterns. However, the mean heart rate increased by 5 beats/min after midazolam injection (p less than 0.05). One infant developed transient apnea, reversed promptly by intravenous flumazenil. Sedation occurred within 1 min after intravenous injection of the drug. No other side effects were noted. Midazolam is a relatively safe and effective sedative for accurate lower esophageal sphincter pressure measurement and esophageal manometry when a mild sedative such as choral hydrate does not work.

Adolescent↗
PubMed1991

Lack of agreement of chromogenic and clotting assays for factor X and protein C in warfarinised plasma.

Coagulation serine proteases can be measured with either a chromogenic substrate assay or a clotting assay using deficient plasmas. It is a concern whether both assays give similar quantitative results, in particular in plasma obtained from patients on long term warfarin therapy. If these two assay methods were interchangeable, then the chromogenic substrate assay has the advantages of precision as well as laboratory automation. We used the intraclass correlation coefficient (rI) to assess the agreement between the two methods in measuring factor X and protein C levels in warfarinised plasma. The results indicate that the extent and pattern of agreement of the two methods for the measurement of the two variables in warfarinised plasma are poor, despite high Pearson product moment coefficients of correlation.

Blood Chemical Analysis↗
PubMed1991

Acupuncture: from needle to laser.

Acupuncture has been used in the treatment of a variety of illnesses for more than 2000 years. The practice of acupuncture is based on a theoretical system different from our understanding of human anatomy and physiology, and has developed through experience and observation. Stimulation of selective acupoints (situated along 'meridians' in the body) by inserting needles is believed to restore bodily functions by promoting the flow of 'vital energy', throughout the system. Other forms of stimulation which have been developed are heat, electrical stimulation, magnetism and, recently, laser. Laser acupuncture offers distinct advantages over the traditional method because the procedure is pain-free and non-traumatic. Clinical applications include the control of pain in osteoarthritis, lumbago and migraine, and anaesthesia for certain surgical procedures, as well as other ailments of the cardiovascular, respiratory and nervous systems. The technique is easy to learn and there is no need for sophisticated instruments. Thus it is especially useful in developing countries where health resources are limited.

Acupuncture Therapy↗
PubMed1991

Discriminant analysis of iron deficiency anaemia and heterozygous thalassaemia traits: a 3-dimensional selection of red cell indices.

The two main causes of microcytic and hypochromic anaemia are iron deficiency and thalassaemia traits. Discriminant analysis based on a simple combination of classical red cell indices have been used to differentiate between iron deficiency anaemia and thalassaemia with varying degree of accuracy. Two new indices are now available from modern cell counters: red cell distribution width (RDW) and haemoglobin concentration distribution (HDW). Our discriminant analysis suggests that RBC, MCHC and RDW contribute significantly to the differentiation between iron deficiency anaemia and thalassaemia in both healthy donors and hospital-patient groups. In the discriminating process, previous workers have overlooked the heterogeneity of anaemia between anaemic groups as well as biological differences in MCV and MCH among the alpha and beta thalassaemia subjects. This study took into account of these biases and proved, for the first time, that differentiation between iron deficiency and thalassaemia by discriminant analysis was clinically reliable and not significantly biased by the severity of anaemia. The diagnostic accuracy of discriminant analysis was confirmed retrospectively by the reallocation algorithm using the jack-knife principle and prospectively by testing the discriminant functions on independent new samples. Selection of the red cell indices contributing to the discrimination of microcytic hypochromic anaemia was based on biological and statistical considerations. The clear separation of red cell index data of iron deficiency anaemia and thalassaemia traits was shown 3-dimensionally by surface plots.

Anemia, Hypochromic↗
PubMed1991

Membrane depolarization was required to induce DNA synthesis in murine macrophage cell line PU5-1.8.

The role of membrane potential (Em) on the initiation of DNA synthesis in murine macrophage cell line PU5-1.8 was investigated with fluorescent probes bis-oxonol and diS-C3-(5). Incubation of PU5-1.8 cells in high K(+)-HEPES buffer or with gramicidin at 37 degrees C for 1h that depolarized the membrane induced [3H]-thymidine incorporation and expression of early response gene such as c-myc and c-fos. When PU5-1.8 cells were treated with a number of agents including fetal calf serum (FCS), lipopolysaccharide (LPS), epidermal growth factor (EGF), N-formyl-methionyl-leucyl-phenylalanine (FMLP) and bradykinin (BK), only FCS caused DNA synthesis and membrane depolarization. Other agents had no effect on these events. The FCS-mediated DNA synthesis in PU5-1.8 cells was inhibited by clamping the membrane potential with valinomycin. Moreover, intracellular alkalinization induced by nigericin at pH 7.9, which is believed to be a permissive signal for mitogenesis, caused membrane depolarization. On the other hand, challenge of cells with phorbol 12-myristate 13 acetate (PMA) suppressed the K(+)-mediated DNA synthesis. However, the treatment of cells with PMA did not change the membrane potential but suppressed the gramicidin-mediated membrane depolarization. These observations suggest that there is a correlation between membrane depolarization and initiation of DNA synthesis in PU5-1.8 cells. PKC may be acting as a modulator in this transducing pathway.

Animals↗
PubMed1991

Membrane depolarization induces protein kinase C translocation and voltage operated calcium channel opening in PU5-1.8 cells. Protein kinase C as a negative feedback modulator for calcium signalling.

Incubation of the murine macrophage tumour cell line PU5-1.8 in K+ (140 mM)-HEPES buffer induced depolarization of the membrane and the translocation of protein kinase C (PKC) to the subnuclear region. Membrane depolarization also induced an increase of intracellular free Ca2+ levels ([Ca2+]i) which was due to the Ca2+ influx. The amount of K(+)-mediated Ca2+ uptake was dependent on the Ca2+ concentration gradient as measured by indo-1 fluorescence and 45Ca2+ fluxes. The depolarization-mediated Ca2+ influx was suppressed by voltage sensitive Ca2+ channel blockers such as nifedipine and verapamil. Furthermore, in Na(+)-HEPES buffer, incubation of cells with a dihydropyridine agonist [3H]PN200-110 produced a dose-dependent saturable binding. On the other hand, short-term incubation of cells with phorbol 12-myristate 13-acetate (PMA) abolished the early phase of 45Ca2+ influx and the rise of indo-1 fluorescence. Depleting cells of PKC or incubating them with PKC inhibitors, H7 and sphingosine, enhanced the uptake of 45Ca2+ and the rise of indo-1 fluorescence. These observations suggest that membrane depolarization caused an activation of PKC and induced Ca2+ influx through the activation of dihydropyridine-sensitive, voltage-operated Ca2+ channels. Data also show that PKC may act as a negative modulator in controlling the Ca2+ response by closing the voltage-operated Ca2+ channel and/or by enhancing the Ca(2+)-ATPase activity during membrane depolarization in PU5-1.8 cells.

Animals↗
PubMed1991

Plasma and lymphocyte cyclic nucleotide response to acute exercise in healthy adults.

Plasma and lymphocytic cyclic nucleotide levels were assayed in 11 (5 male, 6 female) healthy normal adults before and after bicycle ergometry exercise. Lymphocytosis after exercise was observed. Plasma cAMP level was increased by almost 2 fold after exercise. However, plasma cGMP level was not affected. On the contrary, lymphocytic cAMP level was decreased by one third while cGMP level was halved. There were linear regression relationships between maximum heart rate and % difference in lymphocyte count and lymphocytic cyclic nucleotide levels pre- and post-exercise. Our findings demonstrate that higher cardiac output leads to increased lymphocytosis but decreased lymphocytic cyclic nucleotide levels.

Adenosine Monophosphate↗
PubMed1990

Gastric volvulus complicating Nissen fundoplication.

Two cases of gastric volvulus in children are reported, one complete and one partial. Both occurred subsequent to Nissen fundoplication for gastroesophageal reflux. The symptoms at presentation, and the factors predisposing to volvulus postfundoplication are discussed.

Child, Preschool↗
PubMed1990

Effects of acute physical exercise on aryl hydrocarbon hydroxylase activity in human peripheral lymphocytes.

It has been reported that physical exercise may enhance cytochrome P-450 dependent drug metabolism in vivo. In this study we report that the specific activity of aryl hydrocarbon hydroxylase (AHH) in human peripheral lymphocytes (HPL) is enhanced approximately two fold following acute physical exercise. This enhancement of AHH activity in HPL appears to be strongly correlated with enhanced lymphocyte count as well as induced metabolic and exercise stress but not with the intrinsic physical fitness of individuals.

Adult↗
PubMed1990

Driving experience and the risk of traffic accident among motorcyclists.

In a case-control study on the risk of traffic accidents among motorcyclists in Singapore, we demonstrated an inverse monotonic relationship between accident risk and driving experience. As compared to drivers with less that 1 yr of driving experience, the odds ratios (adjusted for race, age and frequency of riding) for those with driving experience of 1-4, 5-9 and 10 yr or more were 0.60, 0.50 and 0.36, respectively. We propose that intensive in-circuit training of learner motorcyclists should replace the conventional on-the-road training on the basis that the former serves to increase their driving experience without subjecting the learner motorcyclists to the risk of sustaining road accident.

Accidents, Traffic↗
PubMed1990

Differentiation between extrahepatic and intrahepatic cholestasis by discriminant analysis.

Discriminant analysis was used to differentiate between extrahepatic biliary atresia and intrahepatic cholestasis. Among the ten laboratory variables tested, three (gamma-glutamyl transpeptidase, alkaline phosphatase and total serum bilirubin) were useful in the differential diagnosis. gamma-Glutamyl transpeptidase contributed most to the discrimination (85%). From a population study of 28 babies with extrahepatic biliary atresia and 24 infants with intrahepatic cholestasis, the procedure achieved a diagnostic accuracy and specificity of 92.9% and an efficiency of 92.3%. The jackknife procedure has also confirmed that the mathematical model was robust for discriminant analysis and therefore it may be valid for screening infants with cholestasis for early surgical intervention. Discriminant analysis is a useful adjunct for differentiation between intrahepatic cholestasis and extrahepatic biliary atresia.

Alkaline Phosphatase↗
PubMed1990

Effects of overweight on lung function.

Spirometric data from 1586 healthy children, who did not smoke, were analysed to examine the effects of overweight as measured by the body mass index (weight/height2) on lung function. Overweight (72 boys, 88 girls) was defined as on or above the 90th percentile weight for height. After having controlled for the confounding variables of height and age, there were positive partial correlations between body mass index and lung function in girls whose weight was normal, in overweight girls, and in boys whose weight was normal, but not in overweight boys. In contrast to adults, body mass index has a positive effect on lung function in girls, whatever their weight. No such correlation between body mass index and lung function was seen in overweight boys. The observations may be accounted for by distinct sex dependent patterns of fat distribution in children.

Adolescent↗