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Biomedical subjects

L Lu

Publications and source records attributed to L Lu.

At least 253 records · Page 14Linked to original sources
PubMed1999

[Gene expression of lipopolysaccharide receptor CD14 and tumor necrosis factor-alpha in rats after thermal injury].

OBJECTIVE: To investigate changes in lipopolysaccharide receptor CD14 and tumor necrosis factor-alpha (TNF-alpha) gene expression in vital organs, and their significance in the pathogenesis of systemic inflammation after burns. METHODS: Wistar rats were subjected to a 35 percent full-thickness scald injury, then sacrificed pre-burn, and postburn 12, 24, 48, 72 hours, respectively. Tissue samples from liver, kidney, lung and intestine were collected to measure CD14 and TNF-alpha mRNA expression. Peritoneal macrophages were harvested by peritoneal lavage to determine CD14 mRNA expression. RESULTS: CD14 mRNA expression increased markedly after thermal injury, peaking at both 12 and 48 hours. Likewise, CD14 mRNA levels were significantly up-regulated in peritoneal macrophages. Gene expression of TNF-alpha elevated markedly in liver, lungs, and kidneys after acute insults. Positive correlation was found between CD14 mRNA and TNF-alpha mRNA in liver, lung, and kidney tissues. CONCLUSIONS: Thermal injury per se can markedly up-regulate both CD14 and TNF-alpha gene expression in various organs. Excessive CD14 mRNA expression may enhance synthesis and release of TNF-alpha stimulated by endotoxin translocation, and the interaction between CD14 and TNF-alpha may play an important role in mediating multiple organ damage secondary to major burns.

Animals↗
PubMed1999

[The effects of lead poisoning on expression of nerve growth factor gene of submandibular gland in mice].

OBJECTIVE: To study the toxicity of lead poisoning to submandibular gland and its effects on nerve growth factor (NGF) gene expression in mice. METHODS: An experimental model with lead poisoning was established and its histopathological changes in the submandibular gland of mice were observed under light and electronic microscopes. Effects of lead poisoning on expression of NGF mRNA in submandibular gland were analyzed quantitatively by human NGF DNA probe labelled with digoxin with in situ hybridization. RESULTS: Body weight of the mice with experimental lead poisoning reduced, and their lead levels in blood and submandibular gland increased. Lobular atrophy, fibrous hypertrophy, angiectasis of the stroma and enlargement of lobule interstitial in mouse submandibular gland with lead poisoning could be found under light and electron microscopes. Their rough surfaced endoplasmic reticulum was extended and mitochondrion swollen. Graphic analysis showed that diameters of the secretory striate ducts and granular tubules decreased in the mice with lead poisoning. Results of in situ hybridization indicated that hybridized signals in the granular and secretory striate ducts and granular tubules reduced significantly, and NGF mRNA expression decreased. CONCLUSION: Lead is toxic to the submandibular gland of mice and can affect their NGF gene expression.

Animals↗
PubMed1999

[Apoptosis of HL60 cells induced by inhibition of bcl-2 with antisense phosphorothioate oligodeoxynucleotides].

OBJECTIVE: To observe the effects of different bcl-2 antisense phosphorothioate oligodeoxynucleotide (ASPO) concentrations in inducing apoptosis of HL60 cells. METHODS: Signs of apoptotic cells were detected by acridine orange staining, transmission electron microscope, flow cytometry and DNA fragment electrophoresis. RESULTS: In presence of ASPO, the apoptosis of HL60 cells could be induced after 24 hours of incubation. The apoptosis rate at ASPO 5, 10 and 20 micromol/L were (9.67 +/- 2.16)%, (18.25 +/- 3.01)% and (23.42 +/- 2.75)% respectively. There was a statistically significant increase in apoptosis as the dose of ASPO increased. After incubation for 72 hours, the apoptotic rates of the 3 different ASPO concentration groups were (9.58 +/- 2.96)%, (29.58 +/- 4.04)% and (36.33 +/- 3.66)% respectively, of which the apoptic rate of HL60 cells incubated with ASPO 5 micromol/L was highest at 48 hours. CONCLUSION: Bcl-2 ASPO can specifically induce apoptosis of HL60 cells. Its effect depends upon the concentration of ASPO.

Apoptosis↗
PubMed1999

[GC-MS analysis of volatile constituents of rhizoma Heterosmilacis].

OBJECTIVE: To extract and analyze the volatile constituents from the dried rhizomes of Heterosmilax yunnanensis(A) and H. chinensis(B). METHODS: Qualitative and quantitative analysis were made by GC-MS and GC. RESULTS: Forty and forty-seven constituents were identified from A and B respectively, the identification rates being 74.85% and 81.26% respectively. CONCLUSION: The volatile constituents of A and B are almost the same, but slightly different in content.

Gas Chromatography-Mass Spectrometry↗
PubMed1999

[Comparative study of dependence of the cell proliferation of Saccharomyces cerevisiae and Schizosaccharomyces pombe on Ca2+].

Under the same experimental conditions, exogenous Ca2+ had no effect on the proliferation of S. cerevisiae, but it could obviously stimulate the proliferation of S. pombe. Ca2+ chelator EGTA had no inhibition effect on the proliferation of S. cerevisiae, but it apparently inhibited the proliferation of S. pombe and the inhibition could be effectively overcome by adding Ca2+. Non-special ion chelator EDTA could inhibit the proliferation of both S. cerevisiae and S. pombe, but the inhibition could not be overcome by adding Ca2+. The results above directly showed that the dependence of the proliferation of the two kinds of yeast on exogeneous Ca2+ was different. The growth rate of S. cerevisiae was about 3 times that of S. pombe and the proliferation of S. cerevisiae was independent on the exogenous Ca2+, which was similar to transformed cells. Therefore, in order to understand the relationship between the disorder of cell cycle and cell transformation, it was very important to study the mechanism of different effects of exogenous Ca2+ on the proliferation of the two kinds of yeast.

Calcium↗
PubMed1999

Silicone oil tamponade combined with lensectomy preserving anterior lens capsule.

PURPOSE: To investigate the therapeutic effect and indication of silicone oil tamponade combined with lensectomy preserving anterior lens capsule. METHODS: Silicone oil tamponade combined with lensectomy preserving anterior lens capsule was performed in 33 cases (33 eyes) of high myopia, proliferative vitroretinopathy (PVR) D grade and giant retinal tear (GRT). 10 cases were only eye and 11 cases had harder nucleus of lens. The surgical methods included: 1. smashing lens nucleus and lensectomy preserving complete anterior capsule; 2. vitrectomy and membrane peeling; 3. usage of liquid perfluorocarbin or retinotomy for drainage; 4. silicone oil tamponade; 5. postoperative Nd; YAG laser for anterior capsulectomy. RESULTS: Follow-up time was 6 months or more in 29 cases. Total retinal reattachment was achieved in 22 cases, macular retinal reattachment in 5 cases. The visual acuity was 20/800 to 20/200 in 13 cases, 20/100 to 20/50 in 12 cases. Visual acuity was significantly improved in GRT group (P < 0.05). Complications included unexpected anterior capsule break intraoperatively, anterior capsule opacity, silicone oil emulsification and liquid perfluorocarbin remaining postoperatively. CONCLUSIONS: Silicone oil tamponade combined with lensectomy preserving anterior capsule was safe and can reduce the operative complications. The indications included: 1. GRT complicated with high myopia; 2. advanced PVR cases complicated with high myopia in which silicone oil must be used; 3. severe lens opacity cases in which silicone oil must be used; 4. complex retinal detachment of only eye.

Adolescent↗
PubMed1999

[Dimerization of aluminum, zinc, vanadium and gallium phthalocyanine-sulfonates in water, aqueous alcoholic solutions and micelles].

The dimerization of Aluminum (III),Vanadium(lV), Gallium(III) tetrasulfonated phthalocyanine (AlTSPc, VOTSPc, GaTSPc) and Zinc(II) bisulfonated phthalocyanine (ZnBSPc) was studied by spectrophotometic method. The dimerization constants KD were calculated from absorbance measurements. The absorption spectra in water, aqueous alcoholic solutions and micelles of phthalocyanine sulfonates aluminum shows the "slow-forming dimer", and VOTSPc, GaTSPc, ZnBSPc show contact dimer formation.

English Abstract↗
PubMed1998

Retroviral delivery of viral interleukin-10 into myeloid dendritic cells markedly inhibits their allostimulatory activity and promotes the induction of T-cell hyporesponsiveness.

BACKGROUND: Dendritic cells (DC) play critical roles in the initiation and modulation of immune responses and may determine the balance between tolerance and immunity. Viral interleukin-10 (vIL-10), encoded by the Epstein-Barr virus, is highly homologous to the "immunosuppressive" cytokine, mammalian IL-10. It impairs antigen-presenting cell function but lacks certain immunostimulatory properties of mammalian IL-10. We accomplished the following: (1) evaluated the effects of vIL-10 protein on DC phenotype and function, (2) transduced mouse bone marrow-derived DC to express vIL-10, and (3) assessed the impact of transgene expression on DC allostimulatory activity. METHODS: DC progenitors propagated from bone marrow of B10 (H2b) mice in granulocyte-macrophage colony-stimulating factor plus IL-4 were repeatedly transduced by centrifugation, using retroviral supernatant obtained from the BOSC 23 ecotropic packaging cell line. To evaluate transduction efficiency, DC were transduced with the retroviral vector MFG-enhanced green fluorescence protein as a marker gene. Transgene and key cell surface molecule expression were examined by flow cytometry. The level of vIL-10 gene product in the culture supernatant was quantitated by ELISA. DC function was assessed by evaluation of the ability of DC to induce allogeneic (C3H;H2k) T-cell proliferation and cytotoxic T lymphocytes in primary mixed leukocyte reactions. Secondary mixed leukocyte reactions were used to test for T-cell hyporesponsiveness. RESULTS: The early addition of vIL-10 protein to cultures inhibited DC maturation and function. vIL-10 gene transfer was achieved with an approximate transduction efficiency of 35 to 40%. Transduced DC expressed vIL-10 at a level of 40 ng/10(6) cells/48 hr. In comparison with controls, vIL-10-transduced cells showed decreased surface expression of major histocompatibility complex class II and costimulatory molecules, reduced ability to stimulate T-cell proliferation and cytotoxic T lymphocyte generation, and potential to induce alloantigen-specific hyporesponsiveness. CONCLUSIONS: DC can be effectively transduced to express vIL-10 and limit their ability to stimulate in vitro. These genetically engineered antigen-presenting cells may have therapeutic potential to inhibit undesired immune responses to allo- or autoantigens.

Animals↗
PubMed1998

Systemic administration of anti-interleukin-10 antibody prolongs organ allograft survival in normal and presensitized recipients.

BACKGROUND: Systemic administration of cellular interleukin (IL)-10 at a dose of 100 microg/day for 1 week after transplantation accelerates mouse cardiac allograft rejection across MHC barriers. This effect is associated with enhancement of donor-specific cytotoxic T lymphocyte and alloantibody (alloAb) titers. To further evaluate the in vivo role of IL-10, we tested the influence of a neutralizing anti-IL-10 monoclonal antibody (mAb) in both normal and donor (skin) presensitized mouse organ allograft recipients. METHODS: Heart or liver transplants were performed from B10 (H2b) donors to C3H (H2k) recipients. Anti-IL-10 mAb (SXC.I) was administered intravenously in a single injection or repeated once daily injections. Cytotoxic activity of graft-infiltrating cells was determined by 51Cr-release assay. Circulating alloAb levels were quantified by complement-dependent cytotoxicity and flow cytometry. RESULTS: Survival of vascularized B10 cardiac allografts in normal recipients was prolonged significantly in the mAb-treated groups. A single injection of 1 mg of anti-IL-10 mAb immediately after heart transplantation gave a similar graft median survival time to repeated injections of lower dose mAb (0.5 mg/day for 6 days after transplantation) (Ig isotype control 11 days; single mAb injection 18 days; multiple injection 20 days). In presensitized recipients, anti-IL-10 mAb from days 0 to 6 significantly prolonged survival of both cardiac and orthotopic liver grafts. Graft median survival time was extended from 5 to 10 days and from 4 to 11 days, respectively. Prolongation of liver allograft survival in presensitized recipients was associated with suppression of circulating alloAb levels and with significant reductions in the incidence of B220+ cells in both grafts and recipient spleens. CONCLUSIONS: The data support an adverse role of anti-IL-10 in allograft rejection; it seems that by reducing alloAb responses, anti-IL-10 mAb may have potential for use as a therapeutic immunosuppressant, particularly in presensitized organ allograft recipients.

Animals↗
PubMed1998

Phenotype, function, and in vivo migration and survival of allogeneic dendritic cell progenitors genetically engineered to express TGF-beta.

BACKGROUND: Administration of donor bone marrow (BM)-derived dendritic cell (DC) progenitors (DCp) that are major histocompatibility complex (MHC) class II+ but costimulatory molecule (CD40, CD80, CD86)-deficient can prolong mouse heart allograft survival This is associated with microchimerism and inhibition of antidonor cytotoxic T lymphocyte (CTL) activity. Genetic modification of these donor antigen-presenting cells to express an immunosuppressive molecule(s) may enhance their in vivo survival and potential tolerogenicity. METHODS: The surface phenotype of B10(H-2b) DCp before and after gene transfer using replication-deficient adenoviral (Ad) vectors was determined by monoclonal antibody (mAb) staining and flow cytometry. Transforming growth factor-beta (TGF-beta) production was quantitated by enzyme-linked immunosorbent assay. Allostimulatory activity of the gene-transduced DCp was ascertained by mixed leukocyte reaction (MLR) and CTL induction. To assess their in vivo migratory activity and survival, the transduced cells were injected subcutaneously into one hind footpad of C3H (H-2k) mice. Tissues (draining popliteal lymph nodes [LN], spleens, and thymi) were removed 1, 2, 7, and 14 days later and stained for donor MHC class II using anti-LA(b) mAb in an immunohistochemical procedure. The mean number of IAb+ cells per unit area was determined. RESULTS: Transduction with a control Ad vector (Ad-LacZ) at 50 multiplicity of infection slightly increased CD40 and CD86 expression and up-regulated the poor allostimulatory activity of the DCp assessed by MLR and CTL responses. These effects on function were negated in Ad-TGF-beta1-transduced cells. After their injection into mouse footpads, the gene-transduced IAb+ cells were observed in maximal numbers in the popliteal LN at day 1 and in marginal zones and T-dependent areas of spleens (peak at day 7) but were rare in thymi. Transduction with Ad-LacZ reduced the numbers of IAb+ cells identified in both LN and spleens at all time points postinjection, suggesting that the vector alone affected DC life span in allogeneic recipients. TGF-beta1 transgene expression not only fully prevented the reduction in DC induced by Ad transduction alone, but also increased numbers and prolonged the survival of donor cells in the spleen, as shown by a two-to fivefold increase in IAb+ cells at days 2-14 compared with control (Ad-LacZ-transduced) DC. CONCLUSION: BM-derived DCp can be transduced efficiently to express TGF-beta1 using an Ad vector. They exhibit very poor allostimulatory activity and similar migration characteristics in vivo to unmodified DCp. Survival of TGF-beta gene-transduced DC, however, is enhanced significantly compared with unmodified and (especially) control Ad-LacZ gene-transduced DC. Genetic engineering of donor DC to express the immunosuppressive molecule TGF-beta promotes their survival in allogeneic hosts and may potentiate their previously reported tolerogenicity.

Adenoviridae↗
PubMed1998

Identification of immediate early genes during TPA-induced human myeloblastic leukemia ML-1 cell differentiation.

Human myeloblastic ML-1 can be induced to differentiate into monocytes/macrophages by 12-0-tetradecanoylphorbol-13-acetate (TPA). In order to understand the molecular mechanism regulating ML-1 cell differentiation, we focused on the characterization of immediate early genes activated by TPA using the mRNA differentiation display polymerase chain reaction (DD-PCR) and Northern analyses. A modified procedure, the reverse dot slot, was developed to confirm upregulated genes during the early stages of TPA-induced ML-1 cell differentiation. DNA sequencing analyses of 10 subcloned cDNA fragments, selected on the basis of the outcome of the reverse dot slot procedure, revealed that eight were derived from distinct genes. Among these clones, one was a novel gene (G07-5), another (A02-1) was highly homologous to the sequence of a fetal brain cDNA fragment, and the remaining six corresponded to jun-D, rantes, ssat, CD 14, ferritin heavy chain (fhc) and transposons Tn10-like transcript, respectively. Although these genes were all upregulated by TPA, the peak time of mRNA expression varied. jun-D, ssat and A02-1 expressions were superinduced in the presence of cycloheximide, which indicates that they belong to the immediate early gene family. On the other hand, TPA-induced rantes expression was not superinduced by cycloheximide, suggesting a protein synthesis-dependent process. As there are no previous reports of expression of these genes in TPA-induced ML-1 cells, little or no information is available concerning their function in mediating myeloblastic cell differentiation. Thus, this study illuminates new avenues of research for elucidating the function of genes regulating terminal differentiation of myeloid progenitors. 1998 Elsevier Science B.V.

Cell Differentiation↗
PubMed1998

Stem cell factor influences mast cell mediator release in response to eosinophil-derived granule major basic protein.

Stem cell factor (SCF) is an important mast cell growth, differentiation, and survival factor. We investigated whether SCF influenced the response of mouse mast cells to an IgE-independent stimulus, eosinophil-derived granule major basic protein (MBP). Mouse bone marrow cultured mast cells (BMCMC) were derived in either concanavalin-stimulated mouse spleen conditioned medium (CM) or SCF. The cloned growth, factor-independent mast cell line Cl.MC/C57.1 was also studied. BMCMC in SCF exhibited cytochemical staining properties, protease and histamine content, and increased serotonin uptake consistent with more mature differentiated mast cells as compared with BMCMC in CM or Cl.MC/ C57.1 cells. BMCMC in SCF released serotonin, 14C-labeled arachidonic acid metabolites and tumor necrosis factor-alpha (TNF-alpha) on stimulation with MBP, while no response was seen from either BMCMC in CM or Cl.MC/C57.1 cells. All three mast cell populations released mediators on stimulation with the cationic MBP analog, poly-L-arginine, indicating that the cationic charge did not explain the selective response of BMCMC in SCF to eosinophil-derived granule MBP. These findings show that SCF significantly influences mast cell differentiation and the responsiveness of mast cells to eosinophil-derived granule MBP.

Animals↗
PubMed1998

Separate domains for desensitization of GABA rho 1 and beta 2 subunits expressed in Xenopus oocytes.

Desensitization of ligand-gated receptor channels is an intrinsic feedback mechanism and prevents the receptor/channels from becoming overly activated thereby maintaining biological function of the nervous system. Desensitization also plays an important role in neuronal plasticity. By taking advantage of biophysical and pharmacological diversities of GABA beta2 subunits from the brain and rho1 subunits from the retina, structural determinants that confer agonist-induced desensitization were identified. A synthetic chimeric receptor/channel was created from the beta2 and rho1 subunits for this investigation. The chimera was constructed from the extracellular N-domain of the beta2 subunit, extending from the amino terminus to the beginning region of the M1 transmembrane segment, and from the C-domain of the rho1 subunit extending from the M1 transmembrane segment to the carboxyl terminus. The C-domain region included the M1 to M4 transmembrane regions and the large intracellular loop between the M3 and M4 transmembrane segments. Homo-oligomeric GABA beta2, rho1, and beta2/rho1 chimeric receptor/channels were individually expressed in Xenopus oocytes, and the desensitization characteristics attributable to each type of subunit were compared. Results from the present study reveal that motifs in the amino-terminal and carboxyl-terminal domains of the beta2 subunit conferred the agonist-induced desensitization; chloroform modulation was linked to specific phases of the GABA-activated current decay.

Amino Acid Sequence↗
PubMed1998

Donor pretreatment with Flt-3 ligand augments antidonor cytotoxic T lymphocyte, natural killer, and lymphokine-activated killer cell activities within liver allografts and alters the pattern of intragraft apoptotic activity.

BACKGROUND: Liver allografts are accepted across major histocompatibility complex (MHC) barriers in mice and induce donor-specific tolerance without requirement for immunosuppressive therapy. There is evidence that passenger leukocytes may play a key role in tolerance induction. Flt-3 ligand (FL) is a recently cloned hematopoietic cytokine that strikingly augments functional dendritic cells (DCs) within lymphoid and nonlymphoid tissue. METHODS: The expression of costimulatory molecules and MHC class II antigen on DCs isolated from livers of FL-treated B10 (H2b) mice (10 microg/day; 10 days) was examined by flow cytometric analysis, and their allostimulatory activity assessed in primary mixed leukocyte cultures. B10 livers from FL-treated donors were transplanted orthotopically into naive C3H (H2k) recipients. Donor cells (MHC class II+) in recipient spleens were identified by immunohistochemistry. Antidonor cytotoxic T lymphocyte activity, and both natural killer and lymphokine-activated killer cell activities of graft nonparenchymal cells and host splenocytes were determined using isotope release assays. Apoptotic activity within liver grafts was determined by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling. RESULTS: DCs isolated from livers of FL-treated donor mice exhibited increased cell surface expression of CD40, CD80, CD86, and IAb, and augmented T cell allostimulatory activity compared with controls. Within 24 hr of organ transplantation, the numbers of donor IAb+ cells within recipient spleens was augmented substantially compared with normal liver recipients. Livers from FL-treated donors were rejected acutely (median survival time, 5 days), whereas control B10 liver allografts survived >100 days. Nonparenchymal cells from rejecting grafts 4 days after transplantation exhibited increased antidonor cytotoxic T lymphocyte, natural killer, and lymphokine-activated killer cell activities compared with cells from spontaneously accepted grafts. This augmented cytotoxic reactivity was associated with histologic evidence of injury to bile duct epithelium and vascular endothelium that was not readily evident in controls. CONCLUSION: Thus, although normal livers provide allostimulatory signals sufficient to elicit an antidonor immune response, regulatory mechanisms that may include apoptosis of graft-infiltrating T cells, and that are overcome by augmenting the number of functional donor DCs, may account for inherent liver tolerogenicity.

Animals↗
PubMed1998

Human Hrs, a tyrosine kinase substrate in growth factor-stimulated cells: cDNA cloning and mapping of the gene to chromosome 17.

Hrs is a 115kDa zinc finger protein which is rapidly tyrosine phosphorylated in cells stimulated with various growth factors. We previously purified the protein from a mouse cell line and cloned its cDNA. In the present study, we cloned a human Hrs cDNA from a human placenta cDNA library by cross-hybridization, using the mouse cDNA as a probe, and determined its nucleotide sequence. The human Hrs cDNA encoded a 777-amino-acid protein whose sequence was 93% identical to that of mouse Hrs. Northern blot analysis showed that the Hrs mRNA was about 3.0kb long and was expressed in all the human adult and fetal tissues tested. In addition, we showed by genomic Southern blot analysis that the human Hrs gene was a single-copy gene with a size of about 20kb. Furthermore, the human Hrs gene was mapped to chromosome 17 by Southern blotting of genomic DNAs from human/rodent somatic cell hybrids.

Adult↗