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Biomedical subjects

Q Li

Publications and source records attributed to Q Li.

At least 1,027 records · Page 57Linked to original sources
PubMed1992

The production of hybridoma cell line secreting monoclonal antibodies against Xanthomonas campestris pv. oryzae and its application in the classification of strains.

By the fusion of mouse myeloma cells (SP2/0-Ag14) and spleen cells derived from BALB/c mice immunized with the preparation of Xanthomonas campestris pv. oryzae Ks-6-6, Os-213, Yz-32 and Yz-24, we obtained 12 hybridoma cell lines secreting monoclonal antibodies. None of the McAbs cross-reacted with the other varieties of plant pathogenetic and non-pathogenetic bacteria. The McAbs could distinguish three variant serotypes of strains. Antibody titers of ascites were about 1:10(3)-1:10(6) when measured by ELISA method. The McAbs could differentiate 6 epitopes. Based on the epitopes, the 63 strains of X. campestris pv. oryzae we collected were grouped into nine groups.

Animals↗
PubMed1992

[Experimental study on tea in inhibiting mutational specificity of 6 antineoplastic drugs].

According to the principles of SOS response, the authors tested the mutational specificity of tea and its inhibitory effects to the mutational specificity of 6 antineoplastic drugs by using the method of mutational and anti-mutational synchronous test. The results revealed that the tea had no mutational toxicity but anti-mutation effect. It also had the inhibitory effect on mutational toxicity of 6 antineoplastic drugs, including Mitomycin C, Bleomycin, Fluorouracil, Cisdiaminodichoroplatinum, Arabinosylcytosin and Mustargen. These results have provided referential basis for further study on anti-cancer effect and clinical use of tea.

Antimutagenic Agents↗
PubMed1992

[An immunohistochemical study of Langerhan's cells (LC), T-cells and the HLA antigen in human cornea].

The distribution of Langerhan's cells (LC), T-cell subsets, and HLA system in 12 normal and 7 morbid corneas, including 4 of suppurative corneal ulcer and 3 of uveogenic endophthalmitis, were investigated with monoclonal antibodies. The results revealed that a small amount of LC and T-cell subsets were present in the limbal region of normal corneas, while large numbers of LC and OKT4+ were observed in the corneas of suppurative ulcer. HLA-ABC antigens were expressed on the epithelial cells and keratocytes of the normal corneas, while the HLA-DR antigens were expressed on the surface of LC at the limbus.

Adolescent↗
PubMed1992

[Experimental study on the influence of acupuncture and moxibustion on interleukin-2 in patients with rheumatoid arthritis].

Rheumatoid arthritis (RA) is referred to the category of Bi syndromes in traditional Chinese medicine. It is regarded as an autoimmune disease, but the pathogenic mechanism is still to be clarified. In order to observe the effects of the treatment of RA with acupuncture and moxibustion on IL-2, 41 patients were divided into warming needle and point injection groups at random, and 19 healthy subjects as control group. The results showed that the IL-2 levels in two RA groups before treatment were obviously lower than that in control group (P 0.05). After treatment the IL-2 level in control group was unchanged, but increased considerably in two RA groups (P 0.01). Generally, IL-2 is considered as a very important signal for regulating immune response. Our results have shown that the decrease of IL-2 in patients with RA should be one of main causes of internal environment disorder, acupuncture and moxibustion as a stress stimulation exerts an influence on the immunity system through neuroendocrine system to improve the IL-2 production.

Acupuncture Therapy↗
PubMed1992

[Preparation of human placenta microvillous membrane and the study of its transferrin receptor].

Human placenta microvillous membrane (PMM) was prepared by differential centrifugation and by sucrose gradient centrifugation, and the transferrin receptor (TfR) was studied using the receptor radioassay with 125I-transferrin as a radioligand. The factors affecting ligand-receptor binding reaction and the characteristics of TfR were also studied. The result showed that there was no significant differences (P > 0.1) in specific binding rates of 125I-transferrin to its receptor between the two membrane preparations, indicating that both of them could be used for TfR analysis, but the method of differential centrifugation was more simple and less time consuming. The study of TfR in sixty cases showed that the TfR binding sites on PMM and Bmax were 3.53 +/- 1.98 x 10(12) sites/mg membrane protein and 6.33 +/- 4.21 x 10(-12) mol/mg membrane protein, respectively. The Kd was 4.95 +/- 3.39 x 10(-9) mol/L, and the highest specific binding was 26% with nonspecific binding less than 3%. The conditions for ligand-receptor binding reaction were optimized when the concentrations of membrane protein and the 125I-transferrin in each test tube were 50 micrograms and 50,000 cpm (specific radioactivity being 2109 kBq/micrograms transferrin) respectively the incubation time was 30 min, and the concentration of polyethylene glycol added for separating B/F was 12% (W/V). transferrin binding to its receptor was characterized by high affinity, high specificity and being saturated.

Cell Membrane↗
PubMed1992

[Surveillance on ViII phage typing and antimicrobial susceptibilities of S. typhi strains in Guangdong Province].

72 S. typhi strains collected in Guangdong were tested for their Vi II phage types and their antimicrobial susceptibilities. The result of Vi II phage typing showed that 62 strains could be divided into definite types. The result of antimicrobial susceptibilities showed that, as national standard reference strains, all the 72 local strains were susceptible to choloramphenical, gentamycin, neomycin and polymycin B and were of different resistance to other 14 antimicrobial agents. The resistant profiles of strains isolated in different ages shared no significant difference. Choloramphenical remains Commonally selectable to treat Typhoid.

Bacteriophage Typing↗
PubMed1992

[Effects of inhaled aerosol of platelet activating factor on pulmonary function and airway responsiveness in normal subjects].

Platelet activating factor (PAF), which was given as an aerosol to normal subjects, caused immediate bronchoconstriction. After the first inhalation of PAF, percentage fall of VP30 was 43.2% +/- 7.1% at five minute. Subsequent inhalations of PAF, bronchoconstriction effect of PAF gradually attenuated. There was an increase in the airway responsiveness to methacholine following inhalation of PAF. The mean PC40 fell from 18.57 +/- 1.69 g.L-1 to 7.01 +/- 2.24g.L-1 (P < 0.01) on day three and returned to baseline in 1 to 2 weeks. DLCO decreased from 3.3 +/- 0.7ml.kPa-1/s to 2.9 +/- 0.4ml.kPa-1/s (P < 0.01) on day three. Chlorpheniramine partially inhibited the bronchoconstriction effect of PAF in a double blind, crossover study. These data suggest that PSF may contribute to the pathogenesis of airway hyperresponsiveness in asthma and the bronchoconstriction induced by inhaled PAF is mediated in part by histamine release.

Adult↗
PubMed1992

[Effects of aluminum, fluorine and their mixtures on the enzyme activities of jejunal mucus membrane in the perfusion of small intestine of rats in vivo].

Buffer (control), F as NaF (100 mmol/L), Al as AlCl3 (32 and 170 mmol/L) and the two mixtures of Al and F (Al:F = 0.3:0.7 and 0.7:0.3) in Tris-buffered media of pH 7.0 were respectively perfused through the small intestine of rats over a period of 40 min. The jejunum was taken out from each animal immediately. Some of its parts were for HE staining; and the others for enzyme histochemical staining. Fifteen enzymes were observed. The results showed that (1) Fluorine chiefly inhibited the metal-enzymes and metal-activated enzymes; aluminum mainly depressed the activities of enzymes in relation to the cell energy metabolism, such as hydrogenases and oxidase. (2) The decreased activities of enzymes induced by Al or F increased significantly after mixing with each other, indicating that the simultaneous existence of Al and F decreased their ionic concentrations, so that strong antagonistic effects on the inhibition of enzymes were noticed since F or Al inhibited enzyme activities by their ions. (3) A high dose of Al intensively inhibited the enzymes related to the cell energy metabolism, which explained why less quantity of Al was absorbed in animals with high dose of Al than that of low dose Al seen in the absorption experiment. (4) The enzyme activities in the animals given high dose of Al mixed with F apparently were elevated in comparison with that in the animals given a pure high dose of Al which was the result of antagonistic effects of F on the inhibition of enzyme activities by Al, therefore the quantity of the absorbed Al was high.

Aluminum↗
PubMed1992

Endothelial leukocyte adhesion molecule-1 in endotoxin-induced uveitis.

Expression of endothelial leukocyte adhesion molecule-1 (ELAM-1) on endothelial cells leads to the attachment of polymorphonuclear leukocytes. The sequential expression of ELAM-1 and major histocompatibility complex (MHC) class II antigen was examined in the eyes of 59 Lewis rats with endotoxin-induced uveitis (EIU) after the injection of Salmonella typhimurium endotoxin. The eyes were enucleated at 2-hr intervals. Hematoxylin and eosin-stained paraffin-embedded sections and immunohistochemically stained cryostat sections were graded by two masked observers. The MHC class II antigen was expressed on cells in the iris and ciliary body 4 hr after injection of endotoxin and on the corneal endothelium, 8 hr postinjection. It was found that ELAM-1 was expressed first on cells of the ciliary body and iris 10 hr after the injection of endotoxin and on the corneal endothelium, 22 hr postinjection. Clinical and histopathologic disease developed 16 hr postinjection. Adherence of polymorphonuclear cells to the corneal endothelium was observed at the time of ELAM-1 expression. In conclusion, expression of ELAM-1 on ocular tissue occurred in EIU and appeared to promote polymorphonuclear cell accumulation in the anterior segment of the eye.

Animals↗
PubMed1991

Identification and characterization of a cis-acting element that interferes with glucocorticoid-inducible activation of the mouse mammary tumor virus promoter.

The rat hepatoma cell line M1.19 is stably infected by the mouse mammary tumor virus (MMTV), and the expression of the virus is induced by glucocorticoid treatment. However, in the 6.10.2 variant of M1.19, an increase in MMTV transcription is hardly detectable upon exposure to hormone. The mechanism of hormone-unresponsiveness in these cells has been unclear. In this study, we show that nuclear extract from 6.10.2 cells contains a specific DNA-binding activity that recognizes a sequence motif extending from positions -163 to -147 on the MMTV promoter. An oligonucleotide probe spanning this region binds a nuclear factor distinct from the glucocorticoid receptor. In vivo competition experiments, where increased amounts of a plasmid containing this element were transfected into 6.10.2 cells, showed a dose-dependent increase in hormonal inducibility of MMTV expression. Together, these results indicate that this sequence motif negatively modulates glucocorticoid-inducible activation of the MMTV promoter. Moreover, we have characterized a nuclear factor that preferentially binds to the coding strand of this element.

Animals↗
PubMed1991

Immunohistochemistry of Terrien's and Mooren's corneal degeneration.

Lamellar keratoplasty specimens from a patient with Terrien's marginal degeneration and a patient with Mooren's ulcer were compared using routine histopathologic and immunohistochemical staining with an avidin-biotin-peroxidase complex. Less than 25% of the resident cells in the Terrien's marginal degeneration specimen expressed major histocompatibility class II antigens compared with 75% to 100% of the resident cells in the Mooren's ulcer specimen. The ratio of CD4 cells (T-helper/inducer) to CD8 cells (T-suppressor/cytotoxic cells) in the Terrien's marginal degeneration specimen was almost 1:1 compared with 24:1 in the Mooren's ulcer specimen. In addition, less than 5% of the infiltrating cells from the Terrien's marginal degeneration specimen stained positive for CD22 (B cells), compared with 25% to 50% from the Mooren's ulcer specimen. These data may help explain why Terrien's marginal degeneration runs a more benign course than does Mooren's ulcer and provides a rationale for the use of immunosuppressive drugs to treat Mooren's ulcer.

Adult↗
PubMed1991

Energy depletion in culture. Adenine nucleotides are altered as in vivo.

Modeling of ischemic phenomena in vitro has been hindered by the inability to create specific alterations in the variables of interest over a defined time-frame. In particular, changes in the adenine nucleotide pool have been quite difficult to mimic because of the putative low metabolic rate in culture and the long times necessary to achieve even partial chemical energy depletion. Here we present evidence for a rapid method of producing a profound chemical energy depletion with the combination of a NADH dehydrogenase inhibitor (amytal) and a mitochondrial proton ionophore (CCCP). Treatment with our protocol in enriched spinal cultures results in a 40% decrease in ATP within 2 min and a fall to one-third of control values by 15 min. The overall pool size of the total adenine nucleotides is decreased 46% by 15 min and does not completely recover after 5 min of reenergization. The ATP/ADP ratio declines to one-third of control values during deenergization and returns to control values after 5 min in control buffer. Such a loss of the total adenylate pool closely mimics that seen in vivo during ischemia and provides an in vitro model system in which the effects of the combination of this means of cellular injury with others (e.g., excitotoxins) may be examined.

Adenine Nucleotides↗