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Biomedical subjects

C L Li

Publications and source records attributed to C L Li.

At least 127 records · Page 7Linked to original sources
PubMed1985

Characterization of cutaneous vascular permeability induced by platelet-activating factor in guinea pigs and rats and its inhibition by a platelet-activating factor receptor antagonist.

Mechanisms of platelet-activating factor (PAF)-induced increases of cutaneous vascular permeability in guinea pigs and in rats were further explored. PAF so far is the most potent vasoactive mediator, being more than 1000-fold more potent than histamine and bradykinin in both species. In guinea pigs, there is a time delay of 5 to 10 minutes before PAF action, whereas, in the rat, the increased vasopermeability occurs immediately following the intradermal PAF injection. Relative vasoactive potencies of PAF and several structure-related analogues in both species correlate very well with their relative inhibition of the binding of 3H-PAF to specific receptor sites on isolated rabbit platelet plasma membranes and their aggregatory abilities of rabbit platelets. Furthermore, the PAF-induced cutaneous vascular permeability is inhibitable by a competitive specific PAF receptor antagonist, kadsurenone, suggesting that binding of PAF to its specific receptor site is the first step to initiate its action of increased cutaneous vascular permeability. Several pure cyclooxygenase inhibitors, including indomethacin, diflunisal, and flurbiprofen, and the dual cyclooxygenase/lipoxygenase inhibitor, BW755C, but not the histamine antagonists, inhibit the PAF-induced vasopermeability in guinea pigs. The inhibition by indomethacin or BW755C can be fully reversed by coinjection intradermally with PAF and prostaglandin E1 but not leukotriene B4. Also, prostaglandin E1 but not leukotriene B4 enhances the guinea pig in vivo response to PAF in this model. However, in rats, none of the cyclooxygenase inhibitors, histamine antagonists, or BW755C inhibit the PAF effect of cutaneous phenomena even though prostaglandin E1 also enhances the PAF potency of the increased cutaneous vascular permeability. Kadsurenone, a competitive specific receptor antagonist, inhibits both histamine- and bradykinin-induced rat cutaneous vascular permeability which suggests that PAF may be involved in the vasopermeability induced by histamine and bradykinin.

Animals↗
PubMed1984

Factors affecting the generation of mast cells from multipotential colony-forming cells.

The cells responsible for the long-term in vitro generation of murine mast cells have been examined. Sequential analysis of all colony types obtained from cultures of spleen or bone marrow cells showed that only colonies derived from multipotential cells (mixed-erythroid colonies) or mast cell progenitors, contained cells responsible for mast cell generation in liquid cultures. Primary colony growth and subsequent maintenance of mast cells in liquid cultures was dependent upon pokeweed mitogen-stimulated spleen cell-conditioned medium (SCM). Mixed-erythroid colonies from 14-day cultures of spleen cells had the greatest capacity for mast cell generation. Analysis by clone splitting and transfer to high (20%) and low (2.5%) concentrations of SCM showed that the concentration of SCM used in either the primary colony culture or subsequent liquid culture phase altered both the proliferative capacity of the mast cells generated and the frequency of mast cell progenitors within individual mixed-erythroid colonies. Thus, mixed-erythroid colonies stimulated with 2.5% SCM contained the highest proportion of mast cell progenitors (34% of colonies) and when stimulated with 20% SCM, approximately fourfold higher numbers of mast cells were produced at weekly intervals from liquid cultures maintained in 2.5% SCM compared to parallel liquid cultures containing 20% SCM. These studies confirm the hemopoietic origin of mast cells and demonstrate that a factor(s) in SCM is able to modulate their proliferative potential.

Animals↗
PubMed1983

The effects of 5-minute ischemia in Mongolian gerbils: II. Changes of spontaneous neuronal activity in cerebral cortex and CA1 sector of hippocampus.

Spontaneous neuronal activity was recorded in the cerebral cortex and the CA1 sector of the hippocampus in gerbils during and after 5-min ischemia, produced by bilateral clamping of the common carotid arteries. It was found that spontaneous activity in both cortical and CA1 neurons ceased within 60s after the onset of ischemia and that it began to reappear 10-20 min after the recirculation. During the next 24 h most CA1 neurons which were recorded showed hyperactivity. This was evident primarily by an increase in spike discharges, whereas recordings from the cerebral cortex were within the preocclusion ranges. On the 2nd day after ischemia, functioning CA1 neurons could not be found, as if they were in a state of functional death, although histological sections showed a general preservation of their cellular structure at that time.

Animals↗
PubMed1980

Establishment of a cell line (NPC/HK1) from a differentiated squamous carcinoma of the nasopharynx.

A long-term cell culture epithelioid cell line was established from a recurrent squamous carcinoma of the nasopharynx of a Chinese male 17 1/2 years after radiation therapy. The cell line, designated NPC/HK1, has been passed 72 times over a period 1 year. The cells have been shown by light and electron microscopies to be of the squamous epithelial type. When they were transplanted subcutaneously into the back of athymic nude BALB/c (nu/nu) mice, tumors developed at the sites of inoculation, which on histological examination were shown to be well-differentiated squamous carcinomas, similar in morphology to the recurrent human tumor from which they were derived. Karyotypic analysis of cells from the cell line demonstrates an aneuploid human type with a modal chromosome number of 74 with both numerical and structural aberrations. Viral particles or Epstein-Barr viral nuclear antigen (EBNA) has not been demonstrated in the cells from the primary culture or several of the subcultures tested. The presence of EBNA in touch smears prepared from the biopsy tissue was inconclusive. Infection of the subcultured cells with EBV from P3HR1 and B95-8 cells was unsuccessful.

Adult↗
PubMed1980

Intracytoplasmic desmosomes in tumor cells.

The occurrence of intracytoplasmic desmosomes in some normal and tumor cells was suggested to develop by cell fusion by previous investigators. In this study, similar structures were found in tumor biopsies and tumor cells in culture. It is suggested that these structures develop by membrane incorporation and dissolution in cells with active membrane turnover.

Cell Membrane↗
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↗