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S Lei

Publications and source records attributed to S Lei.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Flow cytometry for testing chemosensitivity of malignant bone tumors].

OBJECTIVE: To study chemosensitivity and multidrug resistance of malignant bone tumors and to make an individual protocol of chemotherapy with sensitive antitumor agents. METHODS: Apoptosis induced by MTX, ADM, MMC, VP-16, VCR and CTX, and chemosensitivity in 32 fresh specimens of malignant bone tumors were analyzed by flow cytometry (FCM) and quantitative immunofluorescence. The expression of P-glycoprotein (P170) in the specimen and the relation between P170, multidrug resistance, and chemosensitivity were detected. RESULTS: The rate of apoptosis was significantly different in malignant bone tumor cells treated with different drugs: MTX (30.50 +/- 10.22)%, ADM (26.28 +/- 9.35)%, MMC (23.11 +/- 7.38)%, VP-16 (18.17 +/- 6.14)%, VCR (4.44 +/- 2.55)%, and CTX (1.22 +/- 0.59)%. The individual variation of cell apoptosis was prominent in the specimens of same pathological type treated with same agent. There was lower chemosensitivity in the malignant bone tumors with a high expression of P170. CONCLUSIONS: Chemosensitivity testing by flow cytometry is a simple, quick and sensitive assay. Quantitative analysis of expression of P170 could be used to predict multidrug resistance and its chemosensitivity of malignant bone tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1999

[Significance of apoptosis status and apoptosis-associated antigen expression in human colorectal adenocarcinoma sequence].

To investigate the effects of apoptosis on colorectal tumorigenesis and its possible biological significance, the apoptotic frequency in primary cultural cell of 9 normal mucosa, 4 adenomas and 9 adenocarcinomas in time period of 2, 12, 24, 48 hour was measured by flow cytometry. The apoptotic cells index (AI) in situ for 15 colorectal normal mucosa, 7 hyperplastic epithelial, 25 adenomas and 77 adenocarcinomas was identified by the terminal deoxynucleotidyl transferasemediated dUTP-biotin nick end labeling technique (TUNEL). Ki-67 proliferate index (KI), wafl and p53 genes were immunostained with ABC method. The results showed that culture related apoptotic incidence was obviously decreased in cultural tumor cell when compared with mucosa cell after 24-48 hour in vitro. There was a directly positive relationship between the spontaneous apoptosis and Ki-67-index in vivo. The well differentiated or early stage lesions with intensive bcl-2 expression were significantly more likely to have low AI and KI. Both mp53 accumulation and wafl depression which mainly related to KI, had no apparent correlation with AI, bcl-2/bax expression and clinicopathological features statistically; elevatory bax/bcl-2 and pervasive wafl depression led to an increasing AI/KI both in adenoma with atypia and in advanced cancer with distant metastasis or embolus, comparatively. The data indicated that the reduction of susceptibility to inductive apoptosis may contribute to the early phase of tumorigenesis, that AI in vivo may reflect proliferative activity, and that bcl family was closely associated with spontaneous apoptosis and biological behavior of human colorectal cancer.

Adenocarcinoma↗
PubMed1999

[An analysis of DNA content in 405 cases of human tumor by flow cytometry].

This study was intended to evaluate the relationship between the DNA content of cell cycle and the histology in human tumors. We detected the DNA content in 405 cases of fresh human tumor tissue by means of flow cytometry and observed the histology of tumor with light microscopy. The occurrences of aneuploidy in 22 cases of benign tumor and 383 cases of malignant tumor were 27% and 52% respectively. There were differences in aneuploidy in different histologic types of tumor. The aneuploidy in adenocarcinoma was about 50%, that in sarcoma was more than 37%, and that in squamous carcinoma less than 17%. S > or = 10, G2/m > or = 10 or S > or = 20, G2/m > or = 5 were present in malignant tumors, but were not found in benign tumors. The results suggest that there is obvious difference in the occurrences of aneuploidy in benign and malignant tumors and in different histologic type of tumor(P < 0.05). Benign and malignant tumor may be distinguished when SPF and G2/m reach a higher level (P < 0.01).

Carcinoma, Squamous Cell↗
PubMed1999

[Changes of F-actin in neutrophils under fluid shear stress].

Neutrophils are the main defender in the body, and their physiological characters are associated with functions. Because the environments of neutrophils maturation and storage are different from their function environment, they have to adapt thess changes. Filamentous actin (F-actin), as one of the important cytoskeleton components of neutrophils, has different quantity and distribution under different physiological conditions. Previous researches are all focused on static activation of neutrophils using various stimulants such as formyl-methionyl-leucyl-phenylalanine (f-MLP) and tumor necrosis factor(TNF). In our study, Low-Shear 30 and NXE-1 rheometers were used to provide steady or sinusoidaloscillatory fluid shear stress on separated neutrophils. Fluorescent agent Tritc-Phalloidin was added to label F-actin and the mean fluorescent intensity tested by flow cytometry was used as the indication of F-actin quantity and confocal laser scan microscope was used to detect the distribution of F-actin in neutrophils. We found that F-actin polymerization was significantly decreased under both steady and sinusoidal-oscillatory shear stress when the shear stress was below certain level. The density of the cortex F-actin near cell membrane in cells sheared became thinner than in that without shear stress. f-MLP and TNF both could increase actin polymerization in neutophils due to activation. When neutorphils were activated with f-MLP or TNF under shear stress, the quantity of F-actin in the cells was also decreased, but it was still higher than that in the cells absent of f-MLP or TNF. We concluded that neutrophils had different mechanical properties in different fluid environments. F-actin content and distribution would change according to the shear stress values to play their determinant role in neutrophils mechanical adaptation. The mechanism of actin polymerization in neutrophils for mechanical action is probably different from that for chemoattractants and cytokine activation.

Actins↗
PubMed1999

[Effects of fluid shear stress on neutrophil surface expression of adhesion molecules].

Fluid shear is a physiological and functional environment for circulating neutrophils where various chemoattractants and cytokines have different effects on neutrophils, activating them or evoking inflammation. So far there have been abundant in vitro researches demonstrating that while neutrophils are activated, some adhesion molecules, which are expressed on the surface of neutrophils, are necessary to cell-to-cell adhesion, and the quantity or quality of these molecules will be changed. The above results were all obtained under static fluid which is quite different from physiological condition. Recently, we used Low-Shear 30 to provide steady or sinusoidal-oscillated fluid shear stress on separated neutrophils with or without f-MLP/TNF stimulation. FITC-anti CD18 monoclonal antibody and PE-anti CD62L monoclonal antibody were added to label CD18 and CD62L on neutrophils suface respectively. Flow cytometry was used to quantify surface expression and positive cell percentage of these two adhesion molecules. The results demonstrat that fluid shear stress increases the expression of CD18 significantly and decreases the CD62L positive cell percentage, but it does not influence the CD62L expression on the CD62L positive cells. The effects of the different patterns of fluid shear stress are not much different, f-MLP or TNF can slightly decrease the expression of CD18 and make CD62L shedding respectively. When one of the two activators and the fluid shear stress act together, the expression of the two adherent molecules can be added. This indicates that the mechanical and biochemical stiumlative action can produce different effects through different receptors and different signal transduction pathways. So the mechanical environment should be considered in the research of activation and adhesion of neutrophils.

Adult↗
PubMed1998

Involvement of Ras/MAP kinase in the regulation of Ca2+ channels in adult bullfrog sympathetic neurons by nerve growth factor.

The cellular mechanisms that underlie nerve growth factor (NGF) induced increase in Ca(2+)-channel current in adult bullfrog sympathetic B-neurons were examined by whole cell recording techniques. Cells were maintained at low density in neuron-enriched, defined-medium, serum-free tissue culture for 6 days in the presence or absence of NGF (200 ng/ml). The increase in Ba2+ current (IBa) density induced by NGF was attenuated by the RNA synthesis inhibitor cordycepin (20 microM), by the DNA transcription inhibitor actinomycin D (0.01 microgram/ml), by inhibitors of Ras isoprenylation (perillic acid 0.1-1.0 mM or alpha-hydroxyfarnesylphosphonic acid 10-100 microM), by tyrosine kinase inhibitors genistein (20 microM) or lavendustin A (1 microM), and by PD98059 (10-100 microM), an inhibitor of mitogen-activated protein kinase kinase. Inhibitors of the phosphatidylinositol 3-kinase (PI3K) pathway (wortmannin, 100 nM, or LY29400, 100 microM) were ineffective as were inhibitors of phospholipase C gamma (U73122 or neomycin, both 100 microM). The effect of NGF persisted in Ca(2+)-free medium that contained 1.8 mM Mg2+ and 2 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. It was mimicked by a Trk antibody that was capable of inducing neurite outgrowth in explant cultures of bullfrog sympathetic ganglion. Antibodies raised against the low-affinity p75 neurotrophin receptor were ineffective in blocking the effect of NGF on IBa. These results suggest that NGF-induced increase in Ca2+ channel current in adult sympathetic neurons results, at least in part, from new channel synthesis after Trk activation of Ras and mitogen activated protein kinase by a mechanism that is independent of extracellular Ca2+.

Adrenergic Fibers↗
PubMed1998

[Detecting expression of the multidrug resistance gene product (P170) in human tumor tissues and cells by flow cytometry].

We have detected the human multidrug resistance gene (MDR1) product P170 in 29 solid tumor samples and K562 cell line through indirectimmunoflourence staining by flow cytometry using mouse monoclonal antibody (McAb). The results showed that the expression of P170 was detected in 18 samples, the positive ratio being 62.1%; the expression was not detected in 11 samples, the negative ratio being 37.9%; and 99.9% of K562 cells expressed P170. In 16 of the 18 positive samples, the percent ratio of tumor cells for expression of P170 was less than 30%; in the other 2, more than 30%. This indicated that the positive ratio of P170 of most tumor samples was high, but their percent ratio of P170 was low. Thus it provided a parameter for reference in evaluating the efficacy of clinical antitumor treatments.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

[Effect of vasectomy on apoptosis in spermatogenic cells of the male rat].

To explore the effect of vasectomy on apoptosis of spermatogenic cells, we have detected apoptosis in the testis of vasectomized and sham-operated adult rats within a period of 12 postoperative weeks by means of flow cytometry and TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuride triphosphate nick-end labeling) method. Flow cytometry found that, in vasectomized rat, the sub-haploid peak was higher and the percentage of cells with sub-haploid was increased. The total number of positive TUNEL cells in the vasectomized group was greater than that in the sham-operated group (P < 0.001). Compared with the same time-phased sham-operated subgroups, the number of apoptotic spermatogonia and primary spermatocytes in the testes of the subgroups 2 weeks, 6 weeks and 10 weeks after vasectomy as well as the number of spermatogonia of the subgroup 12 weeks after vasectomy were significantly higher (P < 0.05). These findings demonstrate that vasectomy could enhance the apoptosis of spermatogenic cells.

Animals↗
PubMed1998

[The expression of CD11a and CD11b on leucocytes in cerebral thrombosis].

This study sought to understand the mechanism for the increased adhesion of leucocytes and endothelial cells in ischemic stroke. 20 patients with acute cerebral thrombosis and 20 healthy subjects as controls for expression of CD11a and CD11b (adhesion molecules on surface of leucocytes) were tested in vitro by flow cytometry (FCM) method. The results showed that compared with the control group, the patient group had significantly higher rates for expression of CD11a on monocytes, granulocytes and lymphocytes (P < 0.05). The CD11b expression in the patient group was positively elevated on monocytes and granulocytes (P < 0.05), but it was of lower positive rate on lymphocytes and no statistical difference was noted between the patient and control groups. These indicate that the expression of CD11a and CD11b on leucocytes increases in cerebral ischemic damage; thus adhesion of leucocytes and endothelial cells obviously increases. This change may aggravate post-ischemic delayed neuronal death.

Adult↗
PubMed1997

Influence of activity and dietary energy on broiler performance, carcase yield and sensory quality.

1. A total of 2560 male and female Ross broilers were raised to 42 days of age in a 2 X 2 treatment factorial arrangement experiment to investigate the influence of different degrees of physical activity and dietary energy on broiler performance, abdominal fat content, carcase yield and sensory quality. 2. Vertical fans were used to force the treatment birds to walk 3 to 4 times as far as the normal activity birds: birds were fed a normal and a high energy diet (12.55 compared with 13.81 MJ ME/kg) with the same energy/protein, energy/lysine and energy/methionine + cystine ratios. 3. High activity birds had greater body weight (+4.1%), food intake (+5.1%) and ME intake (+5.1%) than normal activity birds. Birds receiving high energy diet had a lower food conversion and food intake than birds receiving normal energy diet. There were no significant differences in body weight or ME intake between birds with different diets. 4. Slaughter yields, both absolute and relative to live body weight, were affected by activity or dietary energy to varying degrees. Breast meat was increased with more activity. The absolute weight of abdominal fat was independent of activity and in males the relative weight of abdominal fat was decreased in high activity birds. 5. Different degrees of activity and dietary energy had only minor influences on broilers sensory quality.

Animals↗
PubMed1997

Regulation of N- and L-type Ca2+ channels in adult frog sympathetic ganglion B cells by nerve growth factor in vitro and in vivo.

To examine mechanisms responsible for the long-term regulation of Ca2+-channels in an adult neuron, changes in whole cell Ba2+ current (IBa) were examined in adult bullfrog sympathetic ganglion B cells in vitro. Cells were cultured at low density in defined, serum free medium. After 15 days, total IBa was similar to the initial value, whereas IBa density was reduced by approximately 36%, presumably due to an increase in neuronal surface area. By contrast, IBa density remained constant after 6-15 days in the presence of murine beta-NGF (200 ng/ml), and total IBa was almost doubled. Inclusion of cytosine arabinoside (Ara-C; 10 microM) to inhibit proliferation of nonneuronal cells, did not affect the survival of neurons in the absence of nerve growth factor (NGF) nor did it attenuate IBa. Ara-C did not prevent the effect of NGF on IBa. There were three independent components to the action of NGF; during 6-9 days, it increased omega-conotoxin-GVIA-sensitive N-type IBa (IBa,N); increased nifedipine-sensitive L-type IBa (IBa,L) and decreased inactivation of the total Ba2+ conductance (gBa). The latter effect involved a selective decrease in the amplitude of one of the four kinetic components that describe the inactivation process. Total IBa was also 55.8% larger than control in the somata of B cells acutely dissociated from leopard frogs that had received prior subcutaneous injections of NGF. By contrast, injection of NGF antiserum decreased total IBa by 29.4%. There was less inactivation of gBa in B cells from NGF-injected animals than in cells from animals injected with NGF antiserum (P < 0.001). These data suggest that NGF-like molecule(s) play(s) a role in the maintenance of IBa in an adult amphibian sympathetic neuron; the presence of NGF may allow the neuron to maintain a constant relationship between cell size and current density. They also show that IBa inactivation in an adult neuron can be modulated in a physiologically relevant way by an extracellular ligand.

Animals↗
PubMed1997

[Effect of tetrandrine on pulmonary vascular morphology in rats with hypoxia pulmonary hypertension].

To investigate the effect of Tetrandrine on pulmonary vascular morphology in rats with hypoxia pulmonary hypertension. We established the model of hypoxia pulmonary hypertension and observed the small pulmonary arterial morphologic changes under light microscope and electron microscope after the rats were treated with Tetrandrine; also, we made morphometric analysis. The results showed that the small pulmonary arteria in rats with hypoxia pulmonary hypertension was thinner than normal ones and had proliferation of smooth muscular cells. Morphometry displayed that the external diameter became smaller and that the ratio of vascular wall thickness to external diameter (M/T%) and the ratio of vascular wall area to total area (MA%) increased. The pathologic change significantly decreased after the rats were treated with Tetrandrine, indicating that Tetrandrine inhibited hypoxia-induced thickening and muscularization of small pulmonary arteria by inhibiting the proliferation of collagenous fibers so that narrowing of small pulmonary arteria was significantly slackened and pulmonary hypertension was alleviated. Therefore, we conclude that tetrandrine may partly prevent the development of pulmonary hypertension.

Alkaloids↗
PubMed1997

[Histopathologic and immunochemical changes in Sjögren's syndrome].

To research into the causes of sjögren's syndrome, we investigated the lacrimal gland tissues of 6 cases of sjogren's syndriome by using electronmicroscopy and immunochemical methods. The results revealed that at the early stage the lacrimal gland cells showed degeneration, irregular arrangement and many intracellular vacuoles. At the middle stage, some lymphocytes infliltrated into the gland tissues. And at the advanced stage, lymphocytes and collagenous fibers were there in substitution of gland cells.

Adult↗
PubMed1996

Nif- phenotype of Azotobacter vinelandii UW97. Characterization and mutational analysis.

We have identified the molecular basis for the nitrogenase negative phenotype exhibited by Azotobacter vinelandii UW97. This strain was initially isolated following nitrosoguanidine mutagenesis. Recently, it was shown that this strain lacks the Fe protein activity, which results in the synthesis of a FeMo cofactor-deficient apodinitrogenase. Activation of this apodinitrogenase requires the addition of both MgATP and wild-type Fe protein to the crude extracts made by A. vinelandii UW97 (Allen, R.M., Homer, M.J., Chatterjee R., Ludden, P.W., Roberts, G.P., and Shah, V.K. (1993) J. Biol. Chem. 268 23670-23674). Earlier, we proposed the sequence of events in the MoFe protein assembly based on the biochemical and spectroscopic analysis of the purified apodinitrogenase from A. vinelandii DJ54 (Gavini, N., Ma, L., Watt, G., and Burgess, B.K. (1994) Biochemistry 33, 11842-11849). Taken together, these results imply that the assembly process of apodinitrogenase is arrested at the same step in both of these strains. Since A. vinelandii DJ54 is a delta nifH strain, this strain is not useful in identifying the features of the Fe protein involved in the MoFe protein assembly. Here, we report a systematic analysis of an A. vinelandii UW97 mutant and show that, unlike A. vinelandii DJ54, the nifH gene of A. vinelandii UW97 has no deletion in either coding sequence or the surrounding sequences. The specific mutation responsible for the Nif- phenotype of A. vinelandii UW97 is the substitution of a non-conserved serine at position 44 of the Fe protein by a phenylalanine as shown by DNA sequencing. Furthermore, oligonucleotide site-directed mutagenesis was employed to confirm that the Nif- phenotype in A. vinelandii UW97 is exclusively due to the substitution of the Fe protein residue serine 44 by phenylalanine. By contrast, replacing Ser-44 with alanine did not affect the Nif phenotype of A. vinelandii. Therefore, it seems that the Nif- phenotype of A. vinelandii UW97 is caused by a general structural disturbance of the Fe protein due to the presence of the bulky phenylalanine at position 44.

Amino Acid Sequence↗
PubMed1996

Antibodies as tools to study the structure of membrane proteins: the case of the nicotinic acetylcholine receptor.

The nicotinic acetylcholine receptor is the prototype of the ionotropic receptor superfamily of proteins, which includes the closely related gamma- aminobutyric acid type A and glycine receptors, and more distantly related serotonin type-3 and glutamate receptors. Several models of the transmembrane topology of the nicotinic acetylcholine receptor subunits were originally proposed based on hydropathy analysis of their deduced amino acid sequences. Antibodies specific to different epitopes of the nicotinic acetylcholine receptor have proven to be valuable probes for examining the validity of those models. Despite important caveats, a viable model for the transmembrane structure and functional topology of the nicotinic acetylcholine receptor subunits has been obtained from the antibody mapping studies. This model, and the associated methodological shortcomings and obstacles that were overcome in the process of its formulation, can legitimately be extended to other members of the ionotropic receptor superfamily and to other membrane proteins as well.

Animals↗
PubMed1996

[Effect of tetrandrine on intraacinar pulmonary arterial structural remodelling and pulmonary hypertension].

Rat's pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline. The influences of tetrandrine (Tet) upon the structure of intraacinar pulmonary arteries (IAPA) was studied by light and electron microscopy. The results indicated that Tet reduced the thickness of IAPA medial membrane, the ratio of the thickness of IAPA medial membrane to the diameter of IAPA, the number of circular muscular artery and partially muscular artery about 16.4%, 30.5%, 24.3% and 16.4% respectively, and Tet increased the number of nonmuscular artery about 24.7%. It also decreased the degeneration of IAPA, collagen of medial membrane, prolife-ration and myoid differentiation of the pericyte, and it increased the number of IAPA. The authors discussed why Tet caused such changes.

Alkaloids↗