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Biomedical subjects

C Chen

Publications and source records attributed to C Chen.

At least 1,279 records · Page 71Linked to original sources
PubMed1981

Studies of the interaction between apolipoproteins A and C and triacylglycerol-rich particles.

We studied the interaction of apolipoproteins A-I, C, and HDL2 with phospholipid-stabilized, triacylglycerol-rich particles to learn more about the molecular mechanisms that underlie the metabolism of chylomicrons. Apolipoproteins A-I, C-I, C-III1 and C-III2 all bound to and destabilized triacylglycerol-rich particles, apparently by removing phospholipids from the particle surface. None of the apolipoprotein C tested, at any concentration, was, however, able to equal the disruptive effect of apolipoprotein A-I. The destabilizing effects of apolipoproteins A-I and C were not additive. Apolipoprotein C-III1 seemed to lessen the disruptive effect of apolipoprotein A-I by binding competitively to triacylglycerol-rich particles. Unexpectedly, previous binding of apolipoprotein A-I to triacylglycerol-rich particles nearly tripled the ability of these particles to bind apolipoprotein C. Destabilization of triacylglycerol-rich particles by apolipoprotein A-I was prevented by HDL2. The protective effect of HDL2 seemed to depend partly on transfer of unesterified cholesterol from HDL2, since the amounts of unesterified cholesterol and apolipoprotein A-I bound to the particles surface showed a strong negative correlation.

Apolipoproteins↗
PubMed1981

Phytohemagglutinin isolectin subunit composition.

The subunit compositions of individual phytohemagglutinin isolectins from red kidney bean Phaseolus vulgaris were examined by isoelectric focusing and sodium dodecyl sulfate electrophoresis on polyacrylamide gels. Isoelectric focusing reveals heterogeneous but unique and non-overlapping protein band patterns for each of the homotetrameric isolectins, E4 and L4. Isoelectric focusing of the intermediate isolectins which contain both subunits (E3L1, E2L2, and E1L3) show all the protein bands common to isolectins E4 or L4 in proportions relative to their suggested subunit compositions. Polyacrylamide gel electrophoresis in a continuous sodium dodecyl sulfate buffer system gives a single protein band for all of the isolectins. In contrast, a discontinuous sodium dodecyl sulfate buffer procedure resolves isolectins E4 and L4 into single major protein bands of apparent molecular weights 31 700 (+/-600) and 29 900 (+/-200), respectively. Each of the intermediate isolectins contained both protein bands and their relative proportion, as determined by absorbance scanning, confirms the phytohemagglutinin isolectin subunit compositions as E4, E3L1, E2L2, E1L3, and L4.

Electrophoresis, Polyacrylamide Gel↗
PubMed1981

Familial lecithin-cholesterol acyltransferase: identification of heterozygotes with half-normal enzyme activity and mass.

Lecithin-cholesterol acyltransferase (LCAT) mass and activity was measured in Canadian kindred of Italian and Swedish descent with familial LCAT deficiency. Four subjects had LCAT mass of 5.21 +/- 0.87 micrograms/ml (mean +/- SD) and LCAT activity of 98.8 +/- 12.0 nmol/h/ml, well within their respective normal ranges. Five family members, including the parents, the maternal grandmother, and two of four siblings of the LCAT deficient subjects, had enzyme mass (2.85 +/- 0.32 micrograms/ml) and activity (50.8 +/- 6.3 nmol/h/ml) approximately one-half that of normal levels. These presumed heterozygotes had normal levels of apolipoproteins A-I, A-II, B and D. The two subjects with LCAT deficiency had no detectable LCAT mass (below 0.1 microgram/ml) or LCAT activity (below 0.76 nmol/h/ml), apolipoprotein A-I and D levels approximately 50% of normal, and apolipoproteins B and A-II levels only 30-35% of normal. LCAT deficiency in this family is determined by an autosomal recessive mode. Furthermore, LCAT levels and activity are determined by two autosomal codominant alleles, LCATn, the normal LCAT gene, and LCATd, the LCAT deficiency gene.

Female↗
PubMed1981

Application of a sperm micro-immobilization test to cervical mucus in the investigation of immunologic infertility.

A complement-dependent sperm micro-immobilization test for antisperm antibodies in cervical mucus was evaluated in 195 infertile women. Positive tests were obtained among 17% of women with "unexplained" and 12% with an "organic" basis for their infertility. The results confirmed previous reports of the presence of cervical mucus antibodies in the absence of corresponding activity in serum. Non-complement-dependent sperm-immobilizing activity was also detected in the cervical mucus of several patients. During a follow-up period of 9 to 24 months, 10% of those with "unexplained" infertility who had complement-dependent sperm-immobilizing antibodies in their mucus became pregnant, compared with 29% of those without antibodies. The corresponding pregnancy rates for patients with "'organic" infertility were 18% and 11%. In four patients with positive tests who subsequently conceived, further tests failed to detect the persistence of the immobilizing activity.

Cervix Mucus↗
PubMed1981

Antigen-specific clones of proliferating T lymphocytes. I. Methodology, specificity, and MHC restriction.

In this report we describe in detail a new method for cloning antigen-specific, proliferating T lymphocytes directly from primed murine lymph nodes after 3 days of activation in vitro. After expansion in liquid culture the cells from the colonies were shown to be antigen specific and to require I-A histocompatible, irradiated spleen cells for stimulation. For hapten-carrier-type antigens, the T cells were shown to be carrier specific in their recognition but they were also capable of distinguishing the presence of the hapten. Recloning of small numbers of these cells in soft agar under conditions of high plating efficiency yielded true clones (i.e., populations derived from a single cell) whose antigen specificity was identical to that of cells from the original colony. The fact that a clone of T cells was I-A restricted in its antigen recognition demonstrates that suppressor T cell function cannot account for the phenomenon of major histocompatibility complex restriction.

Animals↗
PubMed1980

The significance of 5'-nucleotide phosphodiesterase isozymes in the diagnosis of liver carcinoma.

The results of determination of the serum 5'-NPDase isozymes in 95 cases of primary liver carcinoma and other kinds of disease are presented. The 5'-NPDase-V was positive in 83.2% of primary liver cancer cases. This test might be a useful supplement to AFP determination, especially in AFP-negative liver cancer patients. In most patients who had undergone successful liver resection for primary carcinoma, the test became negative. A positive 5'NPDase-V test in patients with cancer elsewhere in the body may suggest liver metastasis. In addition, this test may be of some help in the differentiation of primary liver cancer from other kinds of liver disease. The problem of "false-positive" results of this test is discussed.

Diagnosis, Differential↗