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Biomedical subjects

H C Liu

Publications and source records attributed to H C Liu.

At least 307 records · Page 17Linked to original sources
PubMed1987

Toxicity domain in presynaptically toxic phospholipase A2 of snake venom.

About 42 complete amino-acid sequences of phospholipases A2 (phosphatidylcholine 2-acylhydrolase, EC 3.1.1.4) are known, including those of 13 presynaptically toxic enzymes, but the structural features responsible for the neurotoxicity and distinguishing the toxins from the non-neurotoxic enzymes are far from being clear. In this study, we examined the charged-residue distributions and hydrophobic characteristics based on the sequence data and the predicted tertiary structure and proposed a possible toxicity domain. We found that the presynaptically toxic enzymes have three or four more basic amino-acid residues than the non-neurotoxic enzymes at positions 59, 60, 65, 70-73 and 97 or 98. These residues appear to cluster near the surface region at the N-terminal side. The cationic nature of this basic cluster in the toxin is enhanced by the alpha-amino group of the N-terminus and the dipole moment of helices 96-110 and 1-10. Moreover, these toxic-site residues are usually associated with hydrophobic regions at 1-7, 64-81 and 97-109.

Amino Acid Sequence↗
PubMed1987

Establishment and characterization of five cell lines derived from human malignant gliomas.

We established and characterized five cell lines derived from human malignant gliomas (four glioblastomas multiforme and one highly anaplastic astrocytoma). All cell lines exhibited tumor cell morphology and growth kinetics, and anchorage-independent growth in soft agar. Cytogenetic analysis revealed significant aneuploidy in all five cases as well as clonal chromosomal alterations unique to each cell line. No cell line was tumorigenic in athymic mice. Two of the cell lines were sensitive to carmustine (BCNU) in monolayer and soft-agar cultures. Electron microscopy showed marked variability between cell lines in the number and structure of intracytoplasmic organelles; SF-126 formed collagen fibers in vitro. Immunohistochemical analysis of the surgical specimens showed variable expression of glial fibrillary acidic protein (GFAP) in malignant astrocytes; positive immunostaining for glycoproteins of the extracellular matrix was found predominantly in perivascular regions. In early-passage cultures, only cell line SF-295 expressed GFAP; at establishment, none of the cell lines expressed GFAF or glutamine synthetase. Fibronectin and laminin were expressed by all cell lines in early-passage culture, but expression of these glycoproteins at establishment was variable. Only SF-126 was positively identified by immunostains for procollagen III; this was also the only cell line in which DEAE-cellulose chromatography and SDS-PAGE demonstrated interstitial collagen synthesis. These well-characterized glioma-derived cell lines may now serve as useful tools with which to study the cell biology of gliomas. The synthesis of interstitial collagen by a glioma-derived cell line may suggest a derivation from vascular mesenchymal elements, either reactive or transformed, in the original heterogeneous malignant glioma, rather than from a glial precursor cell.

Adult↗
PubMed1987

Spinal cord proliferative sparganosis in Taiwan: a case report.

A 43-year-old woman suffered from low back pain and bilateral footdrop. A cisternal myelogram unexpected revealed multiple filing defects in the spinal canal extending from the lower cervical region to the caudal equina. Diagnostic exploration revealed numerous cystic organisms adhering to the spinal cord and nerve roots. Histopathological examination showed these organisms to be proliferative sparganum cestode larvae. Although these cestode larval infections have been reported a dozen times in humans from various parts of the world, this is probably the first reported case of spinal cord infection.

Adult↗
PubMed1987

Elevated serum interleukin-2 receptor; increased in vitro immunoglobulin synthesis and lack of response to testosterone-enhanced in vitro interleukin-2 production in ankylosing spondylitis.

The pathogenesis of ankylosing spondylitis (AS) remains unknown, although previous studies have strongly suggested that it may result from immunological aberration. To further explore the pathogenetic mechanisms, in vitro syntheses of immunoglobulins and interleukin-2 (IL-2) by peripheral blood mononuclear cells (MNC), and the serum level of the interleukin-2 receptor (IL-2R) were studied in 35 patients with definite AS and in 28 healthy controls. MNC were cultivated in the presence of pokeweed mitogen (PWM) for seven days. Immunoglobulins in the supernatants were measured by rate nephelometer (Immunochemistry System Analyser II, Beckman.) In vitro synthesis of IL-2 was carried out by cultivating MNC in medium only; in medium containing physiological concentration of the male sex hormone i.e., testosterone 500 ng/dl and estradiol 2 ng/dl; and in medium containing physiological concentration of female sex hormone, i.e., testosterone 50 ng/dl and estradiol 20 ng/dl. IL-2 was quantitated using an IL-2-dependent cytotoxic T lymphoid cell line (CTLL). Serum IL-2R was measured using an IL-2R test kit (CELLFREE, T Cell Sciences, Cambridge, MA). The results showed: In vitro synthesis of IgG, IgA and IgM was significantly higher in AS than in controls; In vitro synthesis of IL-2 was significantly enhanced by testosterone in normal control, but not in AS; and Serum IL-2R was significantly elevated in patients with AS. These findings, viewed in conjunction with previous results here, lead to postulation that an inflammatory process, elicited in HLA-B27-positive males and caused by an infectious agent invading via the mucosa may both cause immunological abnormalities and provoke various symptoms and signs of AS.

Adolescent↗
PubMed1987

Liver alcohol and aldehyde dehydrogenase isoenzymes in Chinese.

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isoenzyme phenotypes were determined in 71 autopsy liver specimens by agarose isoelectric focusing and starch gel electrophoresis, respectively. Ninety percent of the livers examined exhibited a pH-optimum for ethanol oxidation at pH 8.5, instead of 10.5 which is usual among Caucasians. The homozygous ADH2 2-2 phenotype was found to be 59%, and the heterozygous ADH2 2-1 phenotype, 31%. The remaining 10% of the livers, exhibiting a pH-optimum at 10.5, were homozygous ADH2 1-1 phenotype. Accordingly, the gene frequencies of the alleles ADH2(2) and ADH2(1) were calculated to be 0.75 and 0.25, respectively. Fifty-eight percent of the 71 livers examined possessed both the activities of ALDH I and ALDH II isoenzymes, whereas 42% lacked the ALDH I activity. The implications of these distributions of liver ADH and ALDH isoenzyme patterns among Orientals for ethanol elimination, alcohol sensitivity and alcoholism are discussed.

Adult↗