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Biomedical subjects

L G Liu

Publications and source records attributed to L G Liu.

16 recordsLinked to original sources
PubMed2002

New macrocyclic diterpenoids from Euphorbia esula.

The structures of two new macrocyclic jatrophane diterpenoid esters from the whole herb of Euphorbia esula, were established as 11,14-epoxy-3beta,5alpha,7beta,8alpha,9alpha,15beta-hexaacetoxy-12-oxo-13alphaH-jatropha-6(17)-ene (1) and 1alpha,3beta-diacetoxy-5alpha,7beta-dibenzoyloxy-9,14-dioxo-11beta,12alpha-epoxy-2alpha,8alpha,15beta-trihydroxy-13betaH-jatropha-6(17)-ene (2) by a combination of 1D- and 2D-NMR techniques as well as UV, IR and mass spectral data. Bioassay evaluation of all isolates against the human tumor cell lines (B16, KB, SMMC and BGC) indicated that ester 2 was cytotoxic to B16 with the IC50 value being 1.81 microg/ml. In addition, the irritant activity assay indicated that both diterpenoids were inactive (ID(24)50 > 100 microg/ear).

Animals↗
PubMed2001

Modeling translocation of particles on one-dimensional polymer lattices.

We introduce a general random walk model that is an extension of the random walk model proposed by Berg. The model can be used to describe a particle's translocation along a polymeric lattice with a nonuniform distribution of obstacles. These obstacles are representative of DNA-bound proteins, of drugs, and of a DNA packing environment. Using this model in the bacteriophage replication process, we show the effects of random obstacles on an ATP-driven particle's translocation along single-stranded DNA. The principal finding is that the average statistical time of the translocation process decreases with the increase of an obstacle's strength. We also find an interesting relation between the average statistical time and the DNA chain length. Our results can be used to explain some physiological phenomena. They show the usefulness of our model in an analysis of the effect of random obstacles on particles' translocation along one-dimensional polymer lattices.

Adenosine Triphosphate↗
PubMed2001

New jatrophane diterpenoid esters from Euphorbia turczaninowii.

Five new (1-5) and one known (6) jatrophane diterpenoid esters were isolated from the ethanol extract of the whole herb of Euphorbia turczaninowii. Their structures were established by extensive spectroscopic methods. The absolute stereochemistry of 3 beta,5 alpha,8 alpha,15 beta-tetraacetoxy-7 beta-benzoyloxyjatropha-6(17),11E-dien-9,14-dione (1) was confirmed by a single-crystal X-ray analysis coupled with the exciton chirality circular dichroism method. Compounds 1-6 were inactive when evaluated both in a mouse ear inflammation assay and for cytotoxicity against the B16 mouse melanoma cell line.

Animals↗
PubMed2000

[Color-flow duplex Doppler scanning study in the tram flap perforators: a report of 94 consecutive patients].

OBJECTIVE: To investigate the location of transverse rectus abdominis musculocutaneous (TRAM) flap perforators on abdomen skin and the peak systolic flow velocities of the perforators. METHODS: A series of 94 consecutive patient's TRAM flap perforators were detected by color-flow duplex Doppler scanning peroperatively. Perforator locations were tabulated on the abdomen skin according to their vertical position relative to the umbilicus and their lateral location relative to the abdominal midline. RESULTS: The perforators on both left and right side of TRAM flap were quite not symmetry. The peri-umbilical region contained 81.1% of the perforators. All perforators were detected with peak systolic flow velocities ranging from 5 to 81 cm/s. CONCLUSION: The preoperative color-flow Doppler localization of TRAM flap perforators improves the surgeon's ability to design the flap in order to capture the dominant vessels, and select single- or double-pedicle and free TRAM flaps based on each patient's individual characteristics.

Adolescent↗
PubMed1998

Reactivity of sera from systemic lupus erythematosus and Sjögren's syndrome patients with peptides derived from human immunodeficiency virus p24 capsid antigen.

We have previously demonstrated that about one-third of patients with either Sjögren's syndrome (SS) or systemic lupus erythematosus (SLE) react to human immunodeficiency virus (HIV) p24 core protein antigen without any evidence of exposure to, or infection with, HIV itself. Herein, we further characterize the specificity of this reaction using enzyme-linked immunosorbent assay to peptides representing fragments of p24. Characteristic epitope-specific profiles were seen for SS and SLE patients. SS patients had significantly increased responses to peptides F (p24 amino acids 69 to 86) and H (amino acids 101 to 111) and diminished reactivity to peptides A (amino acids 1 to 16) and P (amino acids 214 to 228). SLE patients had increased reactivity to peptides E (amino acids 61 to 76), H, and P. Utilization of peptide P hyporeactivity as the criterion to select for SS patients results in a screen that is moderately sensitive (64%) and specific (79.3%). Adding hyperreactivity to one other peptide (F or H) as an additional criterion yields an expected decrease in sensitivity (to 41%) while increasing specificity (to 93.1%). All sera-reactive peptides from regions of known structure of HIV p24 were located in the apex of the p24 molecule. Thus, the specificity of the peptide reactivities described here indicates a specific pattern of a nonrandom cross-reactivity between HIV type 1 p24 and autoimmune sera which may be partially syndrome specific. The future focus of our work will be to optimize assays of the peptide as diagnostic tools.

Amino Acid Sequence↗
PubMed1992

[A preliminary study of the fibrous capsules around silicone mammary implants in Chinese women].

Specimens obtained from 17 fibrous capsules around the silicone implants were examined with naked eye, and light and electron microscopy. Immunohistochemical staining with various monoclone antibodies was used. It was demonstrated that the main infiltrating cells in the fibrous capsules were mononuclear cells, denoting a rejection reaction. Fibrous tissue was formed to separate the prosthesis from the normal tissue.

Adult↗
PubMed1989

[Effects of CCK-8 of hypothalamus on antral motility in rats].

Cholecystokinin-octapeptide (CCK-8) of 10 ng were injected into lateral hypothalamus (LH) and ventromedial hypothalamus (VMH) in conscious rats, both of which brought about inhibition of antral motility recorded by a strain gauge, the actions were partly antagonised by bilateral vagotomy, but blocked by intravenous infusion of atropine or regitine. It is suggested that both vagus and sympathetic nerves be involved in mediation of function of central CCK-8. In addition, the unit spontaneous discharges of neurons in vagal nuclei were attenuated while CCK-8 injected into LH. On the contrary, the antral motility was stimulated markedly by injection CCK-8-antiserum into LH, indicating that the endogenous CCK-8 in this area exercises a continuous restraint on antral motility in the basal state. CCK-8 cells both in LH and VMH were visualized by PAP method. It may be reasonable to refer this as the histological basis of the identical function on antral motility exercised by CCK-8 both in LH and VMH.

Animals↗