Biomedical subjects

D Li

Publications and source records attributed to D Li.

At least 343 records · Page 19Linked to original sources

PubMed2000

[Study on the clinical characteristics of biphenotypic acute leukemia].

OBJECTIVE: To analyze the biological characteristics and the treatment outcome of adult biphenotypic acute leukemia. METHODS: Immunophenotypes were examined using indirect immunofluorescence method. Biphenotypic acute leukemia (BAL) was diagnosed according to EGIL scoring system. RESULTS: (1) The incidence of BAL in acute leukemia was 3.4%. Percentage for coexpression of B lymphoid and myeloid antigens was 68.4%, for T lymphoid and myeloid antigens 21.1%, for B, T lymphoid and myeloid antigens 10.5%. (2) CD(34) was expressed in 43.75% of the BAL cases. (3) Cytogenetic analysis revealed normal and abnormal karyotypes in 41.7% and 58.3% of the BAL cases, respectively. (4) Six of 19 patients achieved completed remission (CR), but the disease free survivals were all less than 6 months. Treatment outcomes were negatively related to the expression of CD(34) antigen and cytogenetic findings. The BAL patients were poorly responded to therapeutic regimens directed to AML. CONCLUSION: Coexpression of B/M antigens is the commonest subtype in BAL. BAL had a poor prognosis, especially treated with induction regimen directed to AML.

Acute Disease↗

PubMed2000

[Comparison of serological and DNA typings for HLA-AB of cord blood samples].

OBJECTIVE: To evaluate the practical value of serological method for HLA-AB typing of cord blood samples. METHODS: Serological typing results of 1800 cord blood samples were analyzed and 36 of them were compared with that of PCR-SSP (polymerase chain reaction-sequence specific primers). Lymphocytes in cord blood samples were isolated by T-immunomegnetic beads or Ficoll. RESULTS: T lymphocytes isolated by fluorobeads have better activity than that in mononuclear cells isolated by Ficoll. In order to get the more active cord blood cells, samples stored in vitro over 24 hours must be isolated with fluorobeads. Its serological reaction is lower as compared with that of peripheral mononuclear cells. Except 28 samples which had too many dead cells or few cells, there were 310 (17.5%) unconfirmed antigens among 1772 cases by serological typing. The main causes were low specificity of typing reagents, cross reaction, weak serological reaction, high background of dead cells and extra reaction. Confirmed by PCR-SSP, the serological typing had a wrong result rate of 13.88%. CONCLUSION: Although serological typing is rapid and easy, it is necessary to use genetic typing as a complement to it.

DNA↗

PubMed2000

[Study on lumbricus in promoting ligation hemorrhoidectomy postoperative wound healing].

OBJECTIVE: To investigate the effect of Lumbricus in promoting wound healing of ligation hemorrhoidectomy. METHODS: Spray the artificial grown fresh Lumbricus solution on the wound surface of the mixed hemorrhoid patients (treated group) after hemorrhoidectomy and also on wound of the experimental animals, and Lithospermum erythrorhizon medicated gauze was taken as control to observe the effect of treatment on wound healing and histologic change. RESULTS: The mean wound healing time of the treated group was 16.5 +/- 1.8 days, as compared to the control group (21.2 +/- 2.8 days), it was obviously shortened (P < 0.01), 3 days after medication, the growth of epidermis of the treated group was obviously more rapid than that of the control group, no wound infection and granulation hyperplasia were found. The experimental study showed that Lumbricus preparation could inhibit inflammation, bacteria such as Staphylococcus aureus, coli and proteus bacillus was inhibited. In comparison with the control group, the experimental group shortened the healing period for 4 days. On the 4th and 7th day, sacrificed rabbits' capillary count, vessel lumen endothelial cell count, and mesenchymal fibroblast count of the experimental group grower obviously than those of the control group, on the 4th day, the mesenchymal cell mitosis of the experimental group was higher than that of the control group, while on the 7th day, the cell nucleus mitotic index in the experimental group also was higher than that in the control group, from the 3rd day on, wound healing and granulation filling speed of the experimental group obviously more rapid than that of the control group. CONCLUSION: The Lumbricus preparation is cheap in price, easy to preserve, can be used in promoting wound healing, without any toxic and side-effects.

Adult↗

PubMed2000

[Study on the relationship between cadmium immunotoxicity and corticotropin-releasing factor].

To explore the relationship between cadmium immunotoxicity and corticotropin-releasing factor(CRF), murine T- and B-lymphocytes mitogen-induced proliferation function(3H-TdR incorporation method) and CRF levels of hypothalami and blood plasma were observed both in cadmium chloride(CdCl2) and CdCl2 + alpha-hCRF-treated animals in vivo. In cadmium-treated animals, T and B lymphocytes stimulation indexes were significantly lower than those in control(P < 0.05) with a dose dependent response. And interestingly, the central CRF levels in CdCl2-treated groups were significantly higher than those in control (P < 0.05), an increasing CRF level was also observed accompanied by the increase of CdCl2 level. In peripheral blood plasma, no significant difference of CRF levels was found among all groups(P > 0.05). When animals were treated with CdCl2 in combination with alpha-hCRF, no significant difference of B-lymphocyte proliferation function existed among the alpha-hCRF + CdCl2 groups (P > 0.05). Similar results were also observed in detecting T-lymphocyte proliferation function. Hypothalamic CRF levels among various doses of CdCl2 + alpha-hCRF groups showed no statistical difference, but all were higher than those in the control, and peripheral CRF levels had a trend to increase in alpha-hCRF + CdCl2 co-administrated groups. The results suggested that CdCl2 showed an immunosuppressive action upon murine T and B lymphocytes, CdCl2 could cause central CRF increase. alpha-hCRF could partially reduce the cadmium immunotoxicity. Central CRF-mediated immunomodulation was shown in cadmium immunotoxical effects on murine splenic lymphocytes.

Animals↗

PubMed2000

[Animal experimental study on endocrine factors affecting alveolar repair].

OBJECTIVE: To investigate the endocrine effects on activities of alkaline phosphatase (ALP) and acid phosphatase (ACP) and to obtain the mechanism of the resorption and regeneration of the alveolar bone. METHODS: 24 dog models with two-side osseous infrabony pocket were divided into 4 groups randomly and were studied by histologic examination, enzyme cytochemistry and image analysis system. RESULTS: The activities of ALP and ACP, except ACP in the sixth month significantly decreased in the group of thyroidism comparing with that of the control group (P < 0.01), but only the activities of ALP significantly decreased in groups of ovariectomy and diabetes (P < 0.05, P < 0.01), and there was close relationship between enzyme activities and histopathologic variations. CONCLUSION: Alveolar bone repair was regulated by systemic endocrine factors and was associated with the activities of ALP and ACP osteoblasts of and osteoclasts.

Acid Phosphatase↗

PubMed2000

[Production of monoclonal antibodies to broad bean wilt virus and application in virus detection].

Six hybridoma cell lines secretion monoclonal antibodies(MAbs) against broad bean wilt virus(BBWV) were produced by fusing mouse myeloma cells(SP 2/0) with spleen cells from BAL B/c immunized by the BBWV particles. The hybridoma cell lines secreted MAbs stably after cultured in vitro for 3 months or stored in liquid nitrogen and then revived for several times. The titres of ascitic fluids of six MAbs ranged from 1:256,000 to 1:640,000 when measured by indirect ELISA. In agarose gel immunodiffusion test, it showed that the six MAbs represented the same isotype of murine antibodies, IgG1. Six MAbs could detect 4 tested BBWV isolates, but didn't crossreact with other 5 plant viruses. The result of Western blot showed that all the six MAbs can react with the 44.7 kD large coat protein subunit of BBWV. This is the first report of production of MAbs against BBWV.

Animals↗

PubMed2000

[Detection of cucumber mosaic virus subgroup II isolate from tobacco plants in Yunnan province].

One of the spherical virus(designated as CMV-YNb) was isolated form the tobacco plants in Yunnan province. SDS-PAGE showed that this virus contained one polypeptide with molecular weights of 55 kD. The polypeptide was submitted to automated Edman degradation, and found the 10 amino acid sequence of the N-terminus of 55 kD protein shares 100% identity with amino acid sequence of coat protein of CMV-Q, which is belong to CMV Subgroup II. Western blot analysis also showed that this 55 kD protein was serological related to CMV-Q. A 0.9 kb cDNA fragment was amplified by RT-PCR from the RNA template of CMV-YNb with the QCf/QCr primer pair, which was designed according to the CP gene sequence of CMV-Q. The cDNA fragment was then cloned and sequenced. The fragment comprises 865 bp (EMBL accession number: AJ242585), including a 197 bp of 5' intergenic region, 657 bp of CP gene encoding 158 amino acids and a 11 bp of 3' partial non-coding region. Comparison of the nucleotide and amino acid sequences of CMV-YNb CP gene with that of CMV strains belonging to Subgroup II, and that of CMV strains belonging to subgroup I showed 97%-98% and 96%-99%, 75%-76% and 78%-79% identities, respectively. With these data, we made a conclusion that the CMV-YNb is an isolate of CMV Subgroup II.

Amino Acid Sequence↗

PubMed2000

[Studies on the subgenomic RNAs of hepatitis E virus].

Through labeling HEV RNAs with [32P]-phosphate, two subgenomic RNAs at 6.5 to 7.5 h post-infection, one subgenomic RNA at 8.5 to 10.5 h post-infection and none subgenomic RNAs were detected at 21 post-infection or in purified virus. Hybridization results illustrated that the HEV subgenomic RNAs form a 3' nested set which is situated at the 3' end of genome, but their 5' ends do not share a common leader sequence. UV transcription results showed that the HEV subgenomic RNAs were transcribed independently from its promote. Primer extension analysis suggested that the 5' end of large subgenomic RNA was mapped to the initiative region within RNA polymerase region, and the small subgenomic RNA was mapped to the intergenic region between ORF1 and ORF2.

Cell Line↗

PubMed2000

[Studies on monoclonal antibodies of Magnaporthe grisea and its interfering effect on appressorium formation].

Selecting by indirect ELISA eleven hybridoma cell lines, secreting monoclonal antibodies (McAbs) against Magnaporthe grisea were produced by fusing mouse myeloma cells(SP2/0) with spleen cells from BALB/c mice immunized with the mixture of conidia, germ tubes and appressoria of M. grisea using 50% PEG. The result of IFTC test showed that four of McAbs, named as 2B4, 4A1, 1D1, and 2H4 specifically bound to the cell wall surface of the fungus; Western blotting revealed that 2B4, 4A1, 1D1 were recognized different protein antigens from the surface of conidia and germ tubes; These four McAbs could effectively interfere with the appressorium formation both on cellophane membrane and the surface of onion epidermis and inhibit the disease leaf lesions development in vitro test.

Animals↗

PubMed2000

[Principle of evidence-based medicine and its application in clinical trial practice for glutamine and gut permeability].

Evidence-based medicine (EBM) was developed from the progress of traditional clinical model trial patterns. EBM was based on well-designed, randomized, double blind, controlled, multiple center trails in order to assess end pont parameters, prognosis parameters (as: mortality, morbidity of complications and hospital stay etc.), quality of life and cost/effect ratio. It has been accepted in developed countries and could be the guidelines for Chinese clinical trials in the future. This article summarized the principle of EBM and attached with a clinical trial sample about effects of glutamine dipeptide on gut barrier function, post-operative complications and the hospital stay.

Aged↗

PubMed2000

[High level expression of foreign gene via multiple joined operons and a new concept on the restricted constant of total amount of plasmid DNA per cell of Escherichia coli].

OBJECTIVE: To examine the feasibility of linking operons in tandem to enhance expression of heterologous genes in Escherichia coli and to clarify the potential control mechanism of the total plasmid DNA amount in each host cell. METHODS: Two series of expression plasmids, CW11 and CW12, containing 1 to 4 and 1 to 3 heterologous gene operon(s), respectively, were constructed. The molecular size of the CW11 series varied from 5.47 kb to 12.26 kb in 2.25 kb increments. The CW12 series varied from 5.40 kb to 9.72 kb in 2.16 kb increments. Protein expression was analyzed via SDS-PAGE and laser scanning. Plasmid copy number was determined by incorporation with 3H-TdR([3H]-thymidine). RESULTS: No influence of the tandem-joined operons on host growth and plasmid stability was observed. Upon induction, the desired protein accumulated in the CW11 series were 46.0%, 54.8%, 56.1%, and 60.1% of total cell protein. In the CW12 series, the yields were 33.5%, 44.0%, and 47.1% of total cell protein. With increasing size, however, plasmid copy number decreased. Further calculation showed that the total amount of plasmid DNA per cell is restricted to some extent. There seems exists a mechanism to control the maximum level of total plasmid DNA amount in each host cell. CONCLUSIONS: Increasing the target gene dosage by tandem linking of operons enhanced the expression level of a desired protein. Although the size (kb) and the copy number of each plasmid are negatively interrelated, it seems that as for certain plasmids, their total DNA amount per cell is a restricted constant for a specific E. coli strain under identical incubation condition.

Cloning, Molecular↗

PubMed2000

[Effect of organic tin on the morphology and mechanical properties during polyurethane-urea curing process].

The mechanical properties and morphology of crosslined PUU in bulk quasi-prepolymer process was studied by in situ FTIR. From the quantitative change of carbonyl FTIR spectra, the development of morphology between noncatalyzed and catalyzed polymerization process was discussed in detail. The effect of organic tin concentration on the mechanical properties was investigated. It showed that urea carbonyl splitted many small weak bands at different sites with increasing of organic tin concentration, and the catalyst played an important role in controlling the morphology and mechanical properties. It also showed that the mechanical properties reached extreme value when the rate constant of -NCO/-OH reaction equate the rate constant of -NCO/-OH reaction.

Catalysis↗

PubMed2000

[The effect of temperature on the structure and properties of polyurethane-urea by FTIR].

The effect of temperature on the structure and properties of polyurethane-urea was investigated by in situ FTIR. Data from FTIR spectra showed that with increasing temperature the nu NHHbonded areas decrease and the nu NHfree band areas increase. The band site of nu NHHbonded shifted to higher wavenumbers and the band site of nu NHfree keeps constant. The band site of Cfree urethane shift from 1,731 cm-1 to 1,736 cm-1. All kinds of carbonly bands sites shifted to high wavenumbers. But the band sites of amide II and the C=C in aromatic ring shifted to low wavenumbers. The properties of PUU polymers was determined by the structure of soft domains.

Polyurethanes↗

PubMed2000

[Coordination and local structure of Si and Al in silicate glasses and melts: X-ray absorption spectroscopic study].

The coordination and local structure of Si and Al in silicate glasses and melts have been studied using Si and Al K-edge X-ray absorption spectroscopy for the first time. It has been verified that in SiO2-P2O5 and Na2O-SiO2-P2O5 join phosphate silicate glasses, Si atoms remains tetrahedrally coordinated with oxygen when the content of P2O5 is below 32 mol%, but partial Si atoms become octahedrally coordinated with oxygen when the content of P2O5 increases above 32 mol%, and the proportion of the octahedrally coordinated Si atoms increases with the increasing content of P2O5. It has also been demonstrated that Al remains four-fold coordinated with oxygen in ambient NaAlSi2O6-NaAlSi3O8 glasses, but in the same composition glasses quenched at 4.4 GPa and 1,575 degrees C, partial Al atoms becomes five- and six-fold coordinated with oxygen, and at the same pressure and temperature, the proportions of five- and six-fold coordinated Al atoms increases with the increasing content of NaAlSi2O6 in the glasses. Thus, the pressure-induced coordination change of Al in aluminosilicate glasses and melts has been observed for the first time by Al K-edge X-ray absorption spectroscopy.

English Abstract↗

PubMed1999

Up-regulation of type XIX collagen in rhabdomyosarcoma cells accompanies myogenic differentiation.

Rhabdomyosarcomas are known to recapitulate some of the early events in skeletal muscle embryogenesis, and cultures derived from these tumors have been extensively used to elucidate processes associated with the differentiation of primitive mesenchymal cells. These neoplasms have also provided important systems for studying different collagen types. This aspect is particularly relevant to type XIX collagen, which was originally identified from rhabdomyosarcoma cDNA clones. Although this collagen has been localized in vivo to basement membrane zones in a wide variety of tissues, including skeletal muscle, the tumor cells appear to be a unique source of its expression in vitro. We have found that one particular cell line-derived from a peritesticular embryonal rhabdomyosarcoma-produced relatively large amounts of type XIX collagen, especially in those rare instances in which these cells appear to spontaneously differentiate. To characterize this phenomenon, tumor cells were grown under conditions known to induce differentiation in normal myoblast cultures. In response to this treatment, the typical tumor cell morphology consistently and reproducibly switched from polygonal to round/spindle-shaped with the subsequent appearance of some structures resembling myotubes. Concurrently, the cultures commenced a dramatic up-regulation of type XIX collagen and skeletal muscle myosin heavy chain and alpha-actinin in a time-dependent fashion, whereas protein and mRNA levels of other matrix proteins were either decreased or unchanged. Moreover, immunocytochemical analysis revealed that only a subpopulation of the cells was responsible for the increased synthesis of type XIX collagen, alpha-actinin, and myosin, and that the same cells which stained positive for the collagen also stained positive for the muscle proteins. Taken together, the results suggested that type XIX collagen may be involved in the initial stages of skeletal muscle cell differentiation.

Actinin↗

PubMed1999

Expression of the casein kinase 2 subunits in Chinese hamster ovary and 3T3 L1 cells provides information on the role of the enzyme in cell proliferation and the cell cycle.

In order to investigate the in vivo functions of protein kinase CK2 (CK2), the expression of Myc-tagged versions of the subunits, Myc-CK2alpha and Myc-CK2beta, was carried out in Chinese hamster ovary cells (CHO cells) and in 3T3 L1 fibroblasts. Cell proliferation in these cells was examined. CHO cells that transiently overexpressed the Myc-CK2beta subunit exhibited a severe growth defect, as shown by a much lower value of [(3)H]thymidine incorporation than the vector controls, and a rounded shrunken morphology. In contrast, cells overexpressing Myc-tagged CK2alpha showed a slightly but consistently higher value of [(3)H]thymidine incorporation than the controls. The defect in cell growth and changes in morphology caused by Myc-CK2beta overexpression were partially rescued by coexpression of Myc-tagged CK2alpha. In parallel to the studies in CHO cells, the stable transfection of Myc-CK2alpha and Myc-CK2beta subunits was achieved in 3T3 L1 fibroblast cells. Similarly, the ectopic expression of Myc-CK2beta, but not Myc-CK2alpha, caused a growth defect. By measuring [(3)H]thymidine incorporation, it was found that expression of Myc-CK2beta prolonged the G(1) phase and inhibited up-regulation of cyclin D1 expression during G(1). In addition, a lower mitotic index and lower mitotic cyclin-dependent kinase activities were detected in Myc-CK2beta-expressing cells. Detailed analysis of stable cells that were synchronously released into the cell cycle revealed that the expression of Myc-CK2beta inhibited cells entering into mitosis and prevented the activation of mitotic cyclin-dependent kinases. Taken together, results from both transient and stable expression of CK2 subunits strongly suggest that CK2 may be involved in the control of cell growth and progression of the cell cycle.

3T3 Cells↗

PubMed1999

Epicardial ST depression in acute myocardial infarction.

The presence of electrocardiographic ST depression in acute infarction remains controversial and poorly explained. A combined animal and modeling study was performed to evaluate the source of ST changes in acute infarction. In anaesthetized sheep, small infarcts showed uniform ST elevation over the infarction whereas larger infarcts showed marked ST depression over the normal myocardium in addition to the ST elevation. These findings were replicated by bidomain models of the heart. A hollow sphere was used to model a gradually increasing infarct, and this showed that there was a decrease in the ratio of ST elevation to ST depression as the infarct was increased. The current flowing out of the heart must be identical to the current flowing back into the heart. This means that any infarction will produce ST depression as well as ST elevation, the ratio between the two being related to the size of the infarction. Small infarction is associated with a small region of ST elevation and minor ST depression of the remaining myocardium, and as the infarct region increases, the amplitude of the epicardial ST elevation falls and the amplitude of the ST depression increases. Infarction size is proportional to both the height of the ST depression on the epicardium and the strength of the epicardial ST segment dipole.

Animals↗

PubMed1999

Two-dimensional freezing in the liquid-vapor interface of a dilute Pb:Ga alloy.

We report the results of x-ray reflectivity and grazing incidence x-ray diffraction studies of the liquid-vapor interface of a dilute alloy of Pb in Ga over the temperature range of 23-76 degrees C. Our data show that the liquid-vapor interface of this alloy is stratified for several atomic diameters into the bulk liquid and that a monolayer of Pb forms the outermost stratum of the interface. Over the temperature range of 23-56 degrees C, the monolayer of Pb is in an ordered hexagonal phase. At about 58 degrees C, this monolayer undergoes a first-order transition to a hexatic phase, which remains stable to 76 degrees C. An analogy between the observed transition and the first-order melting transition in a one-component classical plasma is suggested.

Journal Article↗