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Biomedical subjects

P J Cheng

Publications and source records attributed to P J Cheng.

30 records · Page 2Linked to original sources
PubMed1994

[Lumbosacral lipomas with spinal bifida].

Spinal dysraphism is usually accompanied with lumbosacral lipoma. The neurological deficits such as lower extremities sensorimotor disturbances, bowel and bladder dysfunction are produced by tethering, compression of lipoma and direct transmission of external force on the spinal cord during growth period. 25 patients treated surgically at our hospital between May, 1985, and January, 1993, were reviewed. Surgical approach was designed for debulking the lipomatous mass, untethering and decompressing the cord, repairing the dural defect and paraspinal muscle cleft. 2-59 months (mean 37.5 mons) after operation the 2 patients whose neurological system were normal before operation remained intact. In other 23 patients, bowel function recovered in 75%, active urination restored and improved in 66.2%. Motor dysfunction and paresthesia of the lower extremities alleviated in 78.3%. A case of mild uremia returned to normal and another moderate case improved. None was deteriorated by the operative procedure except one case in which a posterior nerve root was injured.

Adolescent↗
PubMed1986

Monoclonal antithyroglobulin antibodies derived from immunizations of mice with human eye muscle and thyroid membranes.

A mouse hybridoma clone secreting an immunoglobulin M monoclonal antibody (K-5-4), which reacted with human thyroglobulin (Tg), was obtained from spleen cells of mice immunized with crude membranes of human eye muscle tissues (Em). Its binding to Tg could be inhibited by another monoclonal anti-Tg (F1-11-1) derived from spleen cells of mice immunized with human thyroid cell membranes, but K-5-4 did not inhibit the binding of F1-11-1 to Tg. This finding suggests that K-5-4 may react with a site on the Tg molecule which is susceptible to conformational changes, such as that induced by binding of another anti-Tg antibody at another site on Tg. K-5-4 reacted with human, mouse, rat, guinea pig, bovine, and porcine Tg. Binding and immunohistological staining experiments failed to detect binding of K-5-4 to Em tissue. The very low frequency of one Tg-reacting hybridoma from 6 X 10(8) spleen cells fused after Em immunization contrasts with the relative ease with which monoclonal anti-Tgs were generated from spleen cells of mice immunized with crude human thyroid membranes. In the latter case, 1 anti-Tg hybridoma was generated for every 100,000 spleen cells fused, and an extensive library of monoclonal anti-Tgs was collected. Some of these antibodies were specific for human Tg only, while others cross-reacted with Tg of other animal species. None had the species reativity pattern of K-5-4. The anti-Tgs were used to affinity purify human Tg directly from supernatant of thyroid homogenate; the purified Tg was, in turn, used to affinity purify human polyclonal but monospecific anti-Tg directly from serum of patients in a simple and rapid procedure. We conclude that the monoclonal anti-Tgs are useful reagents in isolating and purifying Tg and anti-Tg.

Animals↗
PubMed1984

In vitro binding of amantadine to plasma proteins.

In vitro binding of amantadine to plasma protein was assessed by ultrafiltration of plasma samples (from a blood bank) to which amantadine hydrochloride had been added. Approximately two-thirds of the amantadine was found to be protein-bound. The degree of protein binding was constant over a plasma amantadine concentration range of 100-2,000 ng/ml.

Amantadine↗
PubMed1982

Development of solid-phase immunoassay using chemiluminescent IgG conjugates.

Solid-phase luminescent immunoassay (LIA) was studied using mainly aminobutyl-ethylisoluminol-IgG conjugates. Different solid-phase supports such as immunobeads, polystyrene balls and tubes gave comparable results although tubes were preferred in most of the assays because of the better linearity and reproducibility obtained and their ease of handling. The properties of the conjugates were tested using both direct and sandwich LIA. Direct LIAs performed using sheep-anti-rabbit IgG coated balls provided information on the antigenicity of the conjugates while the sandwich LIA was the actual working system. A sensitivity of 1 ng was obtained in this system. The stability, easy use, safe handling and low cost of the conjugates coupled with a short assay time make this luminescent system a potential alternative to RIA.

Animals↗
PubMed1979

Forssman-like antibody levels in sera of patients with lung cancer.

Sera of normal individuals or patients with lung cancer were assayed for Forssman-like antibody by a quantitative and specific method using ethylenediaminetetraacetate-containing buffer to inactivate complement in the test serum. It was shown that although Forssman-like antibody levels were distributed widely, (a) the levels of young (20 to 45 years of age) normal subjects of Blood Groups A and AB were lower than those of Blood Groups O and B, (b) the levels of old (60 to 80 years of age) normal subjects were lower than those of young normal subjects of Blood Groups O and B, and (c) the levels of old lung cancer patients were lower when compared to age-matched normal individuals of their blood group.

ABO Blood-Group System↗
PubMed1977

Phenethyl alcohol inhibition of sn-glycerol 3-phosphate acylation in Escherichia coli.

In vivo and in vitro experiments were performed to determine how phenethyl alcohol (PEA) inhibits phospholipid synthesis in Escherichia coli. This drug drastically reduced the rate of incorporation of sn-glycerol 3-phosphate into the phospholipids of an sn-glycerol 3-phosphate auxotroph. PEA also reduced the rate of fatty acid incorporation into the phospholipids of a fatty acid auxotroph. The kinetics of PEA inhibition of the rate of incorporation of sn-glycerol 3-phosphate were almost identical to those of PEA inhibition of the rate of fatty acid incorporation into phospholipids. The in vivo experiments suggested that the rate-limiting step(s) in phospholipid biosynthesis inhibited by PEA is at the level of the acylation of sn-glycerol 3-phosphate or beyond this step. PEA inhibited the sn-glycerol 3-phosphate acyltransferase with either palmitoyl coenzyme A or palmitoyl-acyl carrier protein as the acyl donor. This drug, however, had no effect on the cytidine 5'-diphosphate-diglyceride:glycerol 3-phosphate phosphatidyl transferase, cytidine 5'-diphosphate-diglyceride:L-serine phosphatidyl transferase, and acyl coenzyme A:lysophatidic acid acyltransferase. The in vitro findings suggested that PEA inhibits phospholipid synthesis primarily at the level of sn-glycerol 3-phosphate acyltransferase.

Acylation↗
PubMed1975

Investigations concerning the mode of action of 3,4-dihydroxybutyl-1-phosphonate on Escherichia coli.

Experiments were performed to evaluate the ability of the enzymes of Escherichia coli involved in glycerol 3-phosphate metabolism to recognize phosphonic acid analogues of the natural substrate. Neither the catabolic membrane-bound glycerol-3-phosphate dehydrogenase nor the acyl coenzyme A: glycerol-3-phosphate acyltransferase can use 3,4-dihydroxybutyl-1-phosphnate or 2,3-dihydroxypropyl-1-phosphonate are inhibitors of the reduction of dihydroxyactone phosphate as substrates. The 4-carbon phosphonic acid analogue does not exhibit inhibitory activity for either of these enzymes. While the 3-carbon phosphonic acid analogue has no inhibitory effect upon the catabolic dehydrogenase, it does appear to have a slight but reproducible inhibitory effect on the acyltransferase. Glycerol 3-phosphate and 3,4-dihydroxybutyl-1-phosphonate by glycerol 3-phosphate:NAD (P) oxidoreductase. rac-2,3-Dihydroxypropyl-1-phosphonate does not appear to be recognized by this enzyme. The apparent K-i for snglycerol 3-phosphate is 19 muM and for D-3,4-dihydroxybutyl-1-phosphonate it is 42 muM. In addition the glycerol 3-phosphate:NAD(P) oxidoreductase catalyzes the reduction of 4-hydroxy-3-oxobutyl-1-phosphonate (apparent K-m of 182 muM), a phosphonic acid analogue of dihydroxyacetone phosphate. 3,4-Dihydroxybutyl-1-phosphonate is both a competitive inhibitor (apparent Ki of 740 muM) and a substrate (apparent K-m of 450 muM) for the CDP-diglyceride: glycerol 3 phosphate phosphatidyltransferase but it has no effect upon CDP-diglyceride:L-serine phosphatidyltransferase. The relationship ofthese in vitro studies to in vivo investigations is discussed.

Acyltransferases↗