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Biomedical subjects

G Chan

Publications and source records attributed to G Chan.

At least 91 records · Page 5Linked to original sources
PubMed1987

A study of prescribed H1-antihistamine preparations over a period of 12 months in community pharmacy.

A survey on the prescribing pattern of H1-antihistamine preparations was carried out in four socio-economic areas in Liverpool: the City Centre, an Affluent Area, a Poor area and a Council Estate. The purpose of this study was to find out which H1-antihistamines were prescribed from the wide range available; to discover if there was a trend in the use of these agents over a 12-month period and to suggest possible explanations for these findings. The majority of H1-antihistamine preparations were prescribed in the Affluent Area followed by the City Centre, Poor Area and the Council Estate. In all four areas, over 7.0% of all total items dispensed in a year contained H1-antihistamine drugs, and the lowest use (3.7-9.2%) fell in the summer months while the highest use was in January (8.2-14.1% of items containing H1-antihistamine dispensed per month). Thus the general trend in the use of these drugs may not follow the trend of the hay fever season and it is probably true that H1-antihistamines were more frequently prescribed for treatment of other conditions (common cough and cold) than rhinitis alone. The most widely prescribed classes of H1-antihistamines were alkylamines and ethanolamines, followed by the phenothiazines and ethylenediamines while the piperazines were not prescribed. Triprolidine, diphenhydramine, promethazine and brompheniramine were the top four most widely prescribed drugs.

Dosage Forms↗
PubMed1986

Bilirubin diffusion through lipid membranes.

The possibility that bilirubin can diffuse through lipid bilayers is investigated with liposomes prepared from dipalmitoylphosphatidylcholine (DPPC), egg phosphatidylcholine (egg PC) with 22 mole percent cholesterol, and a lipid extract preparation from N115 neuroblastoma cells. Liposomes were prepared with internalized bilirubin and bovine or human serum albumin, and bilirubin efflux into an exogenous solution of human serum albumin was measured. Efflux from DPPC liposomes was significantly higher above the phase transition temperature than below it. This change was dependent on the lipid undergoing a phase transition and could not be accounted for by 6 K change in temperature. Maximum bilirubin efflux from egg PC-cholesterol liposomes was found to depend on the relative internal and external albumin pools, suggesting an equilibrium distribution of bilirubin between them. These observations demonstrate that bilirubin can diffuse freely through these lipid membranes.

Bilirubin↗
PubMed1985

Bilirubin toxicity in neural cell lines N115 and NBR10A.

The toxicity of bilirubin was investigated in 2 neural cell lines NBR10A and N115 using a quantitative dye assay 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium biomide (MTT) as a measure of cell viability and [3H]thymidine incorporation as a measure of DNA synthesis. Short exposures (up to 2 h) to bilirubin, even up to a bilirubin-albumin molar ratio of 1.5, yielded no evidence of toxicity using these assays. At longer exposure times (24 h) a decrease in cell viability and [3H]thymidine incorporation was detected at a molar ratio of 0.8 when the bilirubin concentration was 0.1 mM or higher, whereas lower bilirubin levels at this molar ratio showed no deleterious effect. The effect of bilirubin is more pronounced at a molar ratio of 1.5 with longer incubation periods. The MTT assay showed the N115 cells appeared to be more resistant to bilirubin cytotoxicity than NBR10A cells, a finding which was not obtained from [3H]thymidine incorporation studies. This discrepancy can be explained by the fact that we are measuring two different variables; the MTT assay estimates the number of viable cells at the end of the experiment by measuring mitochondrial function whereas the [3H]thymidine assay measures the rate of DNA synthesis during the last 2 h of the experiment. The concentration effect of bilirubin is evident from the [3H]-thymidine studies in that at a molar ratio of 1.5 and bilirubin concentration of 0.075 mM or higher, there is both cell kill (decrease in DNA) and inhibition of [3H]thymidine incorporation (decrease in specific activity).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

[Nonspecific immunity factors and elimination of circulating immune complexes in patients with myocardial infarct in the 1st phase of rehabilitation].

A considerable increment of humoral immunity parameters was demonstrated during the 3d-5th week after the onset of myocardial infarction (MI). The levels of IgG and IgE were increased, and those of circulating immune complexes (CIC), decreased significantly in patients with their first diagnosed infarction, as compared to those with repeated MI. Patients with repeated MI showed significantly reduced blood C3c, C4 and the phagocyte index in the presence of high blood levels of CIC and C-reactive protein, as compared to patients with primary infarction. The results are indicative of a considerable activation of the complement and the phagocytic system and CIC elimination in patients with their first MI diagnosis, and the absence of such a stimulation in repeated MI cases.

Adult↗
PubMed1984

High malformation rates and decreased mortality in infants of diabetic mothers managed after the first trimester of pregnancy (1956-1978).

Over a period of 23 years we accumulated data on 182 pregnant juvenile diabetic subjects during pregnancy, labor, and delivery. Diabetic subjects were evaluated generally after the first trimester of pregnancy. Data examined included diabetic class, maternal complications of pregnancy, and infant morbidity and mortality. Data were analyzed in two periods-before and after 1970. In the second period, maternal polyhydramnios and acidosis rates improved, neonatal problems of homeostasis did not change significantly, and combined fetal and neonatal losses fell from 34.7% to 16.4%. The neonatal malformation rate, however, increased from 1.4% to 16.8% and was not influenced by maternal age or diabetic class.

Adolescent↗
PubMed1984

Further purification of neutrophil migration inhibition factor from T lymphocytes (NIF-T): evidence that NIF-T and leukocyte inhibitory factor (LIF) are immunologically distinct.

Neutrophil migration inhibition factor from T lymphocytes (NIF-T) purified by antibody affinity chromatography and gel filtration chromatography was radioiodinated and identified as a 26,000-MW protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). NIF-T was identified by elution of biological activity from gel fractions and selective adsorption of a radioiodinated mediator by HL60 cells differentiated in the presence of dimethyl sulfoxide (DMSO) to develop receptors for NIF-T. A goat neutralizing antibody for NIF-T neutralized and immunoprecipitated migration inhibition activity in the conditioned medium from Mo T-lymphoblast cells and human peripheral blood lymphocytes (PBL) cultured with concanavalin A (Con A), but not from RPMI 1788 B-lymphoblast cells with leukocyte migration inhibitory factor (LIF) activity. These studies distinguish NIF-T both chemically and immunologically from LIF.

Animals↗
PubMed1984

Characterization of mouse and human monoclonal antibodies cross-reactive with SLE serum antibodies to guanosine.

Two new monoclonal antibodies, one a mouse IgM and the other a human IgM that reacted with guanosine, were compared to human serum antibodies from patients with systemic lupus erythematosus (SLE). The human monoclonal antibody was polyspecific in its binding to the nucleoside bases, whereas the mouse monoclonal antibody was relatively specific for guanosine when compared by using an enzyme-linked immunosorbent assay (ELISA). Neither antibody bound polyguanylic acid or denatured single-stranded (ss) DNA, however. Serum IgG antibodies from seven patients with SLE cross-reacted with the mouse monoclonal antibody and showed considerable specificity for guanosine. In contrast, the human serum IgG antiguanosine antibodies also bound ssDNA but not dsDNA or polyguanylic acid. Serum IgG antibodies to guanosine measured by ELISA from the seven SLE patients had a decreased response when compared to the total serum IgG response to ssDNA, and most of the antibodies that bound guanosine also bound ssDNA. These studies provide new evidence that there are specific IgG antibodies to guanosine in SLE sera that are a small fraction of the antibodies to ssDNA. Further efforts to define the role of these guanosine antibodies in SLE may provide a better understanding of the basic mechanisms responsible for the development of SLE in man.

Animals↗
PubMed1980

Holoprosencephaly in a Down syndrome child.

Gross malformation of the central nervous system (CNS) is rare in Down syndrome (DS). To our knowledge we report for the first time the association of trisomy 21 and holoprosencephaly. Because of the low probability of chance concurrence due to unrelated causes, a causal relationship between these two conditions in the patient must be presumed. The anatomic similarity of the holoprosencephalic defect in this infant to that seen in others with autosomal dominant, recessive, sporadic, or syndromal forms of holoprosencephaly, supports the hypothesis that: a) this CNS defect is a causally nonspecific developmental field complex (DFC); b) the increased incidence of such DFC's in the DS represents the result of a nonspecific decrease of developmental homeostasis [Waddington, 1975] due to autosomal aneuploidy.

Abnormalities, Multiple↗
PubMed1980

Clinical relevance of the plasma reserve albumin binding capacity for bilirubin (RABC) and "free" bilirubin concentration.

An analysis of 55 plasma samples from 46 jaundiced newborn infants showed that endogenous "free" bilirubin levels bear no significant correlation to reserve albumin binding capacities for bilirubin as determined by both the Sephadex G-25 gel filtration and the enzymatic peroxidation technique (r = 0.14, p less than 0.05). This contrasts with the significant correlation between the "free" bilirubin concentrations and the bilirubin/albumin molar ratios in the same plasma samples (r = 0.75, p less than 0.001). The results of this study suggest that if "free" bilirubin is the "driving force" in the pathogenesis of bilirubin encephalopathy then the use of the reserve albumin binding capacity for bilirubin as the only guide in predicting the risk of kernicterus may not be adequate.

Bilirubin↗
PubMed1979

Plasma carnitine levels during intravenous feeding of the neonate.

The premature infant has a limited capacity for fatty acid oxidation. This study shows that solutions commonly used for intravenous feedings in the newborn infant contain no carnitine. Infants maintained on this solution have significantly lower total, free, and acylcarnitine levels as compared to when they are fed orally with expressed human milk or a proprietary formula, which is known to contain carnitine. The exogenous supply of carnitine to the premature infant may have a significant influence on the ability to stimulate optimal fatty acid oxidation.

Amino Acids↗
PubMed1979

Hong Kong.

Explore the source record for details and available documents.

Hong Kong↗
PubMed1978

Lipid metabolism in the neonate. III. The ketogenic effect of Intralipid infusion in the neonate.

The ketogenic potential of Intralipid was studied in two groups of infants: 12 were SGA and 15 AGA; all were clinically stable and less than 48 hours of age. During four-hour Intralipid tolerance tests, the SGA infants achieved significantly higher plasma TG and FFA levels. Both groups of infants significantly increased the concentration of ketone bodies; however, there was no difference in the levels achieved. In view of the slower clearance rate of TG and the higher levels of FFA in SGA infants, it is speculated that in addition to a possible defective lipoprotein lipase system and a decrease in number and size of the adipose cells, beta-oxidation of FFA to ketones may be occurring at a slower rate. The generation of high levels of ketones during Intralipid infusion period in both groups of infants indicates that SGA infants can handle ketone bodies as readily as AGA infants.

Dietary Fats↗
PubMed1976

Bilirubin quantitation with lipemic plasma.

1. In the presence of lipemia, the estimation of BR by diazo method is variable and hence unreliable. 2. The estimation of BR in lipemic plasma by the use of the A-O bilirubinometer yielded BR levels which were consistently lower than theoretical values. 3. By regression analysis of the percent error in BR estimation, (using the A-O bilirubinometer) and TG Concentrations, a straight line is obtained. Based upon this line, a correction factor for plasma BR concentration in the range of 5-25 mg/dl can be obtained if the degree of lipemia is known.

Bilirubin↗
PubMed1976

Variance in albumin loading in exchange transfusions.

To assess the rationale of albumin priming prior to exchange transfusions, 42 hyperbilirubinemic infants who required exchange transfusions were randomly assigned to one of two groups. Group I consisted of 15 infants who were given intravenously 1 gm/kg of salt-poor human serum albumin one hour before the exchanges. Group II, which consisted of 27 infants, received simple exchanges. No statistical differences were found in variations in reserve albumin-binding capacity, bilirubin, albumin, or red cell bilirubin at pre and one-hour post albumin infusion in the primed infants. The amount of bilirubin removed per kilogram is directly correlated to plasma bilirubin concentration (r=0.87). No significant difference in efficiency on bilirubin removal was seen between the two groups. Beneficial effects of albumin therapy was apparent only in those infants with low RABC as determined by the sephadex gel filtration technique.

Bilirubin↗