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Biomedical subjects

C L Li

Publications and source records attributed to C L Li.

At least 19 recordsLinked to original sources
PubMed1992

Rhodamine123 reveals heterogeneity within murine Lin-, Sca-1+ hemopoietic stem cells.

Murine bone marrow Lin-, Ly6A/E+ cells have been fractionated on the basis of rhodamine123 retention into Rh123med/hi and Rh123lo subpopulations. These populations have different responses to hemopoietic growth factors with respect to in vitro colony formation. Cells from either fraction were not stimulated by only granulocyte-colony-stimulating factor (G-CSF), granulocyte/macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF), interleukins 1 and 6 (IL-1 and -6), or leukemia inhibitory factor (LIF) alone. The Rh123med/hi, but not the Rh123lo fraction, contained cells that could be stimulated by either stem cell factor (SCF) or IL-3 alone. When combinations of growth factors were added, the Rh123med/hi fraction produced more colonies, and responded to a wider range of factor combinations than the Rh123lo population. When tested in vivo, both populations contained no detectable day 8 colony-forming unit-spleen (CFU-S), and similar frequencies of day 13 CFU-S. When transplanted into lethally irradiated recipients (100 cells/recipient), significant numbers of donor cells (67-73%) were found in the peripheral blood of Rh123lo recipients. Both myeloid and lymphoid cells were of donor origin. By comparison, the Rh123med/hi population produced recipients with 1-2% donor cells in peripheral blood, the majority of which were lymphoid.

Animals↗
PubMed1992

Long-term hemopoietic repopulation by Thy-1lo, Lin-, Ly6A/E+ cells.

Murine bone marrow Thy-1lo, Lin-, Ly6A/E+ cells have been isolated by fluorescence-activated cell sorting (FACS). This population contained up to 27% in vitro colony-forming cells (CFC) when stimulated by interleukin 3 (IL-3) and 5% day-12 spleen colony-forming units (CFU-S) (uncorrected for seeding efficiency). As few as 100 cells were able to reconstitute the myeloid and lymphoid compartments of lethally irradiated recipients for periods of up to 72 weeks. Over the range of 30-560 transplanted cells, three patterns of engraftment were observed; the proportion of donor cells increased gradually to values of > 90%, gradually declined, or remained static over the 72-week observation period. When the donor cell percentage in the peripheral blood exceeded 60%, both myeloid (neutrophils and monocytes) and lymphoid (T- and B-lymphocytes) cells were of donor origin. Primary animals containing > 60% donor cells in their peripheral blood were able to engraft secondary recipients with donor cells of both myeloid and lymphoid lineages. Primary animals with < 20% donor cells in their peripheral blood contained bone marrow cells that were only able to produce lymphoid cells in the peripheral blood of secondary recipients. With > 90% of animals, including both primary and secondary recipients, there were no large fluctuations in the proportion of donor myeloid or lymphoid cells in the peripheral blood. Where changes occurred, with three exceptions, these were gradual. These data suggest that the Thy-1lo, Lin-, Ly6A/E+ population is heterogeneous and contains in vitro CFC, day-12 CFU-S, and long-term repopulating cells for both the myeloid and lymphoid lineages and cells capable of long-term repopulation of only the lymphoid lineage.

Animals↗
PubMed1992

Induction and termination of afterdepolarizations and triggered arrhythmias by drugs in cat heart in vivo.

In order to investigate some anti-triggered arrhythmic drugs, the afterdepolarizations and triggered arrhythmias were induced by cesium chloride and the monophasic action potentials of the left ventricular epicardium in vivo were recorded by using a contact electrode in 58 cats. These results suggested that a) early- and afterdepolarizations, oscillatory afterpotentials and some different kinds of triggered arrhythmias were induced by cesium chloride, b) sodium valproate (150 mg/kg) could prevent CsCl-induced triggered activities, c) lidocaine (5 mg/kg), ethmozine (5 mg/kg) and sodium valproate (150 mg/kg) could terminate CsCl-induced ventricular tachycardias. The present studies provide a basically experimental evidence for treating triggered arrhythmias in clinic.

Action Potentials↗
PubMed1992

[Triggered activities induced by cesium chloride and terminated by drugs in cat heart in vivo].

Monophasic action potential (MAP) of the left ventricular epicardium in vivo in 58 cats were recorded by using a contact electrode. The results showed that early after depolarization, delayed after depolarization, oscillatory afterpotential, and some kinds of triggered arrhythmias were induced by CsCl (iv 0.5 mmol.kg-1), that these afterdepolarizations and triggered arrhythmias were prevented by sodium valproate, and that ventricular tachycardias induced by CsCl was terminated by lidocaine, moricizine, and sodium valproate.

Action Potentials↗
PubMed1991

Soft filamentous woven polyester arterial prosthesis from China.

Woven polyester arterial prostheses have traditionally been known for their tight construction and smooth surface which has limited their healing capacity and resulted in poor attachment of their internal and external capsules. A new woven prototype has recently been developed in the Peoples' Republic of China. Among its unique features are its high physical porosity, softness and flexibility. This study undertook a series of in vitro tests to characterize its structure and physical properties in comparison with four commercial polyester grafts of North American origin. In addition, an animal trial was completed in which the new prototype was implanted as an infrarenal aortic substitute in 20 dogs for periods ranging from 4 h to 12 month. The in vitro tests confirmed a unique lightweight, highly porous, satin weave construction. Because of its high water permeability, preclotting was necessary before implantation. Once preclotted and installed, no significant blood loss was observed, and 19 of the 20 grafts remained patent at the sacrifice. Rapid full-width healing was achieved with tightly bound capsules, and more extensive tissue ingrowth was observed. Further work is needed to evaluate its long-term durability as an arterial substitute.

Animals↗
PubMed1991

[Neolignans from Piper polysyphorum C.DC].

Piper polysyphorum C.DC (Piperaceae) is indigenous to the southern part of China. In the course of screening for inhibitors of platelet activating factor (PAF), the nonpolar fraction was found to exhibit PAF inhibitory activity. One new neclignan named polysyphorin and three new enantiomeric forms of (+)-virolongin, (+)-grandisin and (+)-lancifolin D were isolated. Two known neolignans, wallichinine and hancinone D were also obtained from the same sources. The structure determination was based upon spectroscopic analysis (UV, IR, CD, MS, 1HNMR, 13CNMR, COSY) and derivative preparation. The structure for polysyphorin was established as threo-delta 7'-7-hydroxy-3,4,5,3',5'-pentamethoxy-8-O-4' -neolignan. It is a racemic enantiomer. The PAF inhibitory activities were reported.

Drugs, Chinese Herbal↗
PubMed1990

Expression of human alpha-globin and mouse/human hybrid beta-globin genes in murine hemopoietic stem cells transduced by recombinant retroviruses.

Murine cell lines releasing helper-free recombinant retroviruses containing human alpha-globin and mouse/human hybrid beta-globin genes were generated. The expression of the hybrid beta-globin gene but not the human alpha-globin gene was regulated appropriately in infected mouse erythroid leukemia (MEL) cells. Murine bone marrow cells were infected by coculture with virus-producing cells and transplanted into lethally irradiated syngeneic recipients. Greater than 90% of the spleen colonies (12-15 days), which are derived from hemopoietic multipotential stem cells, showed proviral integration. Various levels of expression of the transduced globin genes were detected in all of the provirus-positive spleen colonies. Proviral sequences and transcripts from the transduced globin genes could also be detected in a few long-term reconstituted recipients in an observation period of 10 months after transplantation.

Animals↗
PubMed1990

[Analysis of serum free amino acid profiles in patients dying from major burns].

An analysis of serum free amino acid profiles in 8 patients dying from major burns revealed that free amino acid began to decrease in shock period, decrease 31.12% in infection period and 41.3% before death in comparison with the control group. The amount of BCAA-also decrease 36.27% in infection period and 56.83% before death. If the serum free amino acid in major burn drops steadily, the prognosis will be worse.

Adult↗
PubMed1989

Retrovirus-mediated gene transfer into embryonal carcinoma and hemopoietic stem cells: expression from a hybrid long terminal repeat.

Retroviral vectors can be used as an efficient gene delivery system in a wide variety of cell types. However, in some cell types, such as embryonal carcinoma (EC) cells or normal bone-marrow cells the expression of genes introduced by retroviral vectors has been very inefficient. This expression block has severely hampered the application of retroviral vector systems in those cell types. The enhancer sequences present in the long terminal repeat (LTR) of retroviruses are known to be responsible for the tissue specificity of viral expression. Therefore, we set out to construct a vector in which this enhancer element has been replaced. A recombinant retrovirus was constructed in which the enhancer from the Moloney murine leukemia virus LTR was replaced by the enhancer of a mutant polyoma virus (PyF101) that was selected to grow on EC cells. A neomycin-resistance marker (neoR) was placed under the transcriptional control of the hybrid LTR. Following infection with this virus, neoR was expressed in EC cells, as well as in the hemopoietic progenitor cells present in normal murine bone marrow. Moreover, upon transplantation of infected bone marrow cells into lethally irradiated mice, neoR expression was sustained in hemopoietic cells of the engrafted recipients.

Animals↗
PubMed1989

[In vitro assessment of candidacidal activity of human leukocyte myeloperoxidase preparation].

Myeloperoxidase (MPO), present in the azurophilic granules of human polymorphonuclear neutrophils, is important in the oxygen-dependent microbicidal activity of neutrophils. The purpose of our study was to investigate the therapeutic potency of the MPO preparations. This paper is to present our primary work on MPO isolation and its microbicidal activity assay. White blood cells, isolated freshly from normal donors, were lysed with cetyltrimehylammonium bromide to liberate myeloperoxidase. The enzyme preparation was partially purified by 50% (NH4)2SO4 precipitation followed by 65% (NH4)2SO4 precipitation. A hundred million leukocytes yielded 1.03 mg protein of the MPO preparation with the RZ of 0.31. The specific activity of the MPO preparation was about 29.25 u/mg. When 0.672 units of the MPO preparation were incubated with about 10(7) clinical isolates of Candida albicans in the presence of 0.2 mmol/L H2O2 and 0.14 mol/L NaCl. It was detected that 95.58 +/- 0.64% of the organisms were killed in the methylene blue staining system.

Antifungal Agents↗
PubMed1989

[The isolation and identification of PAF inhibitors from Piper wallichii (Miq.) Hand-Mazz and P. hancei Maxim].

Platelet activating factor (PAF) is a highly potent endogenous phospholipid mediator, involved in various inflammatory and cardiovascular disorders. As part of a research program dealing with PAF inhibitors isolated from Piper plant species, we have isolated kadsurenone (I), denudatin B (II), and N-isobutyl-deca-trans-2-trans-4-dienamide (III) from Piped wallichii (Miq.) Hand-Mazz. and P. hancei Maxim. In a continuing search for potential PAF inhibitor from plants, using PAF induced platelet aggregation as a guide, a new neolignan named hancinone D (IV) was isolated from P. hancei maxim. By X-ray analysis it was identified as a racemate. The X-ray analysis led to a revision of the previously made structure assignment of hancinone C. Another new neolignan named wallichinine (V), which was identified as an analogue of (IV), along with the known compounds hancinone C (VI), galgravin (VII), dihydropiperlonguminine (VIII) and crotepoxide (IX) were isolated from P. wallichii (Miq.) Hand-Mazz. The structure determination was based upon spectroscopic analysis. All of the compounds were for the first time obtained from both plants. In the test of platelet aggregation caused by PAF, I, II, V, VI, VII showed inhibitory activity, whereas III, IV, VII, IX showed no activity.

Anisoles↗
PubMed1989

Echocardiographic observation on changes of left ventricular structure and function in healthy elderly.

The method of M-mode and 2-dimensional echocardiography was employed in 81 healthy persons to compare the difference in left ventricular structure and function between the elderly group (n = 41, aged 60-76 years) and the control group (n = 40, 22-58 aged years). The results revealed: 1) Aging of cardiovascular system was structurally as well as functionally reflected by echocardiogram, with echocardiographic findings appearing earlier than clinical manifestations. 2) Myocardial contractility and pump function of the elderly were often maintained in good status at rest. 3) Latent depression of left ventricular diastolic function was frequently seen in the elderly. LAD, AE, MVV and EPSS were found to be sensitive compared with the control group, (P less than 0.05, less than 0.001, less than 0.001, less than 0.001, respectively) and useful indices, which can be readily determined. Therefore, in order to evaluate the status of cardiac structure and function of the elderly accurately, it is important to refer to the normal values of relevant age group and draw conclusions from multi-parameters.

Aged↗
PubMed1988

Studies on the inhibitory effect of tetrandrine on silica-induced fibrogenesis in vitro.

Two cell culture systems composed of rat peritoneal macrophages and 2BS fibroblasts were used to study the inhibitory action of tetrandrine on collagen and glycosaminoglycan synthesis. The activation of silica-treated macrophage supernatants stimulated collagen synthesis by 2BS fibroblast cells. Tetrandrine had an inhibitory effect on the biosynthesis of collagen and glycosaminoglycans. The increase in the content of hydroxyproline, representing collagen, was verified by comparing it with that of DNA.

Alkaloids↗
PubMed1979

Decremental conduction in a mammalian peripheral nerve.

Conduction velocities of the A-beta, A-delta and C-fibers in isolated vagal nerves were measured before, during, and after the nerve was exposed to sodium-deficient hypotonic solutions. The solution was kept at 23 degrees C. Recorded at a conduction distance of 18 mm and with the nerve in a 0.25% NaCl solution, the conduction velocity of the A-beta component in the response was found to decrease at an average rate of 1.07 m/s per min; of the A-delta, 0.35 m/s per min and of the C-fibers, 0.020 m/s per min. Thus, the A-delta component in the response would disappear in about 29 min; the C-component, in 49 min; and the A-beta component, in 54 min. Recorded at a distance of 36 mm, the decrease in conduction velocity of the A-beta was 1.40 m/s per min, of the A-delta, 0.43 m/s per min, and of the C-fibers, 0.023 m/s per min. Thus, recorded at this conduction distance, the A-delta would disappear in 20 min; the C-component, in 36 min; and the A-beta component, in 42 min. These findings indicate that when decremental conduction occurs in a mammalian peripheral nerve exposed to these solutions, the decrement is most apparent in the A-delta component, then the C-fiber component, and finally the A-beta component in the nerve. Similar observations were obtained in nerves exposed to 0.5% NaCl solution except that the rate of decrement was slower.

Animals↗