Biomedical subjects

Li Yang

Publications and source records attributed to Li Yang.

At least 217 records · Page 12Linked to original sources

PubMed2004

[The mechanism of anti-tumor immune response against mouse melanoma to xenogeneic vaccination].

OBJECTIVE: To investigate the immunological mechanism for inhibiting melanoma growth in mouse by vaccination with xenogeneic melanocytes. METHODS: Xenogeneic vaccine was prepared from pig eye melanocytes. By means of indirect ELISA the antibodies against pig melanocytes and B16 melanoma cells in immunized mice sera were detected and the immunoglobulin subclass were analyzed. Then after purification, the immunoglobulins were used for the inhibition of cell proliferation in vitro. Analyses of cross-reactive antigen in both pig melanocytes and B16 melanoma cells were performed by Western blot. Xenogeneic vaccine was used before B16 melanoma challenge in C57 BL/c mice and then the growth of tumor was monitored. Meanwhile, other mice immunized with xenogeneic vaccine were depleted of NK cells or CD4+ or CD8+ T lymphocytes. RESULTS: The antibodies against pig melanocytes and B16 melanoma cells in mice sera were not detected by indirect ELISA until 2 weeks after first xenogeneic vaccination, and after the first finding, the antibody titers increased with the time of immunization. The anti-tumor activity and production of autoantibodies, conspicuously those of the elevated IgG, could be abrogated by the depletion of CD4+ T lymphocytes. The cross-reactive antigen with 180 kda protein in both pig melanocytes and B16 melanoma cells was confirmed. Xenogeneic vaccination resulted in inhibition of tumor growth in 90% of the immunized mice. The protective immune response elicited in this fashion was dispelled in the mice depleted of CD4+ T lymphocytes. However this response was found in 70% of the mice depleted of CD8+ T lymphocytes, and the depletion NK cells did not influence the anti-tumor effect of the vaccine. CONCLUSION: The anti-tumor immune response is capable of inhibiting melanoma growth; both humoral immunity and cellular immunity could be induced by xenogeneic melanocytes vaccination. This immune response is mainly mediated by CD4+ T lymphocytes.

Animals↗

PubMed2004

[Inhibition of tumor growth and metastasis via local administration of recombinant human endostatin adenovirus].

OBJECTIVE: The growth and metastasis of solid tumors are dependent on angiogenesis. Endostatin, the C-terminal proteolytic fragment of collagen XVIII, is a potent endogenous angiogenesis inhibitor. The authors designed a topical antiangiogenic gene therapy with recombinant human endostatin adenovirus (Ad-hEndo) and assessed its effects on the inhibition of angiogenesis in vitro, and tumor growth and metastasis in vivo. METHODS: Malignant cells (A549) were infected with Ad-hEndo. The expression of recombinant protein and the inhibition of cultured human umbilical vein endothelial were investigated. Immunodeficient A549 nude mice were treated with intratumoral injection of Ad-hEndo, the empty vector Ad-control or saline (NS). The dose-response, side effects, and serum concentration of endostatin were observed. RESULTS: Recombinant endostatin protein was detected in the infected tumor cells with different MOI Ad-hEndo and its inhibitory effect on endothelial cells growth was shown. In animal study, the volume of tumor and the number of pulmonary metastatic lesions in the Ad-hEndo treatment group were significantly smaller than those in the control groups (P<0.05). CONCLUSION: The present findings provide evidence of the anti-tumor effects of the endostatin and may be important for the further use of it in topical antiangiogenic gene therapy of cancer.

Adenoviridae↗

PubMed2004

[Pharmacokinetics and targeting characteristics of adriamycin after canine hepatic arterial embolization with adriamycin-lipiodol emulsion].

OBJECTIVE: To study the phamacokinetics and targeting characteristics of adriamyin in dogs following embolization of hepatic artery with adriamyin-lipiodol emulsion (AD-E). METHODS: After injection of adriamycin solution and the emulsion, respectively, into the hepatic artery via a femoral artery of the dogs, the concentration of adriamycin in the peripheral venous blood and hepatic tissue were determined by high-performance liquid chromatography. RESULTS: The concentration of adriamycin in peripheral venous blood was significantly lowered after AD-E embolization in comparison with that after adriamycin solution injection. Adriamycin concentration in the hepatic tissue at 10, 24, and 48 h after AD-E embolization was 5.42, 3.33 and 2.38 times that of adrimycin solution group, respectively. CONCLUSION: Compared to adriamycin solution, AD-E as an embolic agent can significantly alter the serum pharmacokinetics and liver targeting characteristics of adriamycin.

Animals↗

PubMed2004

[Association studies of G352A polymorphism of dopamine transporter gene in Han Chinese attention deficit hyperactivity disorder patients].

OBJECTIVE: To investigate association of the new polymorphism G352A in the dopamine transporter gene (DAT1) exon 15 with attention deficit hyperactivity disorder (ADHD) in Han Chinese children. METHODS: The new mutant polymorphism G352A in the dopamine transporter gene (DAT1) exon 15 was found by the fluorescently-labeled dye-terminators assay. The study samples were comprised of 337 ADHD children, 207 unrelated controls and 201 integrated ADHD trios (included proband and biological parents). Associations of polymorphisms with ADHD and its subtypes were examined by: (i) comparing cases and controls; and (ii) using family-based association study in transmission-disequilibrium test (TDT). RESULTS: The allele frequencies at the DAT1 G352A locus in the control samples were 79.5% for 352G and 20.5% for 352A respectively. Association studies revealed no association between G352A in exon 15 of DAT1 and ADHD. But after a stratification by gender, there was possible association between G352A and ADHD girls: the 352G allele had a tendency to be preferentially transmitted to ADHD girls. CONCLUSION: There is no association between G352A, the new polymorphism, in exon 15 of DAT1 and ADHD. The 352G allele has a tendency to be preferentially transmitted to ADHD girls, but the findings require replication before drawing a definitive conclusion.

Adolescent↗

PubMed2004

[Effect of ligustrazine on airway remodeling in asthmatic rats].

OBJECTIVE: To observe the effect and mechanism of ligustrazine on the airway remodeling. METHODS: Thirty-two SD rats were randomly divided into 4 groups: the normal group (A), the model group (B), the ligustrazine low-dose group (C, 40 mg/kg) and the ligustrazine high-dose group (D, 80 mg/kg), with 8 rats in each group. The chronic asthmatic model was established by repeated inhalation of ovalbumin. The changes of collagen and transforming growth factor-beta(1) (TGF-beta(1)) contents in the airway wall, the thickness of smooth muscle and basement membrane, inner and outer diameter were measured by the computerized image analysis system. RESULTS: The thickness of smooth muscle and basement membrane were (11.3 +/- 1.3, 11.3 +/- 1.7) microm in D group, (19.7 +/- 1.8, 19.8 +/- 1.6) microm in B group, the difference being significant (P < 0.01), as compared with A group [(10.6 +/- 1.2) microm, (9.8 +/- 1.6) microm] and C group [(11.6 +/- 0.9) microm, (12.3 +/- 1.8) microm], the difference being not significant (all P > 0.05). The difference in the ratio of inner diameter to outer diameter was significant between D group (0.77 +/- 0.06) and B group (0.63 +/- 0.05), P < 0.01. The contents of collagen type III and TGF-beta(1) were (21 +/- 5, 26 +/- 5) in D group, (55 +/- 7, 69 +/- 14) in B group, the difference being significant (P < 0.01). The differences were also significant when C group [32 +/- 8, 38 +/- 10] was compared with D group (P < 0.05) and B group (P < 0.01). The contents of collagen type I showed no difference among the 4 groups (A group: 34 +/- 13, B group: 44 +/- 8, C group: 36 +/- 8, D group: 39 +/- 8; all P > 0.05). A close correlation between TGF-beta(1) and collagen type III was demonstrated (r = 0.844 2, P < 0.01). CONCLUSION: Ligustrazine might suppress airway remodeling by decreasing the expression of TGF-beta(1) and reducing deposition of collagen.

Animals↗

PubMed2004

[Determination of trace zinc, manganese, cadmium and lead in aloe by microwave-digestion atomic absorption spectrometry].

A microwave digestion procedure was developed for the determination of trace Zn, Mn, Cd and Pb in aloe-leaf cuticle and aloe-leaf gelatin, using the obturated vessel microwave digestion system with a pressure controlling part, and the amounts of these trace metallic elements were determined by atomic absorption spectrometry after microwave digestion. The effects of the composition of digestion solution, the ratio of the sample to digestion solution, and the digestion time were studied. It is satisfactory to apply the microwave digestion procedure to the determination of Zn, Mn, Cd and Pb under the optimized condition with the recovery of 95.0% to 110.0% and RSD of 0.3% to 6.2%. The results show that this method is rapid and simple with low environmental contamination and complete digestion of the sample.

Aloe↗

PubMed2003

[Association between tryptophan hydroxylase gene polymorphisms and attention deficit hyperactivity disorder with or without learning disorder].

OBJECTIVE: To investigate the relationship between two tryptophan hydroxylasec (TPH) gene polymorphisms, A218C and A-6526G polymorphisms, and attention deficit hyperactivity disorder (ADHD) with or without learning disorder (LD). METHODS: Blood samples were taken from 132 trios with probands of ADHD with LD and 221 trios with probands of ADHD without LD. DNA was extracted and PCR was performed to amplify the fragments of A218C amd A-6526G polymorphisms. NheI and MboI were used to detect different alleles of the two polymorphisms separately. transmission disequilibriumtest (TDT) and haplotype analysis were used to test the association of the two polymorphisms of TPH gene and ADHD with or without LD. RESULTS: Haplotype block composed by A218C and A-6526G polymorphisms was related to ADHD with LD (chi(2) = 9.362, df = 3, P = 0.025). The haplotype of 218A/-6526G was significantly untransmitted to the probands with ADHD with LD (chi(2) = 9.252, df = 1, P = 0.002). CONCLUSION: TPH gene and the haplotype of 218A/-6526G may be related to ADHD with LD.

Adolescent↗

PubMed2003

Lysosomal acid lipase deficiency causes respiratory inflammation and destruction in the lung.

The functional roles of neutral lipids are poorly understood in the lung. Blocking cholesteryl ester and triglyceride metabolism in lysosomal acid lipase gene knockout mice (lal-/-) resulted in a high level of neutrophil influx in the lungs as early as 2 mo of age. Bronchoalveolar macrophages appeared foamy and gradually increased in number with age progression. Affymetrix GeneChip array analysis of lung mRNA showed increased levels of proinflammatory cytokine (including IL-1beta, IL-6, and TNF-alpha) and matrix metalloproteinase (including MMP-8, MMP-9, and MMP-12) expression in lal-/- mice. With age progression, some areas of lal-/- mice developed severe abnormal cell proliferation and alveolar remodeling. In other areas, alveolar destruction (i.e., emphysema) was observed. In addition, Clara cell hypertrophy and hyperplasia developed in conducting airways. The pathophysiological phenotypes in the lal-/- mouse lungs became more severe with increasing age. The studies support the concept that neutral lipid metabolites play essential roles in pulmonary homeostasis, inflammatory responses, remodeling, and injury repair.

Animals↗

PubMed2003

An engineered multidomain bactericidal peptide as a model for targeted antibiotics against specific bacteria.

We constructed a peptide consisting of a staphylococcal AgrD1 pheromone fused to the channel-forming domain of colicin Ia and named it pheromonicin. This fusion peptide had bactericidal effects against methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA, respectively), but not against Staphylococcus epidermidis or Streptococcus pneumoniae. Growth rates, vital staining and colony forming unit (CFU) counts showed that pheromonicin did not merely suppress growth but killed S. aureus cells. The specificity of pheromonicin was shown by the absence of bactericidal effects against an accessory gene regulator (agr) locus knockout of S. aureus, and a dose-dependent inhibition of the bactericidal effects of pheromonicin by competition with corresponding free AgrD pheromone. In vivo, all pheromonicin-treated mice survived administration of MRSA that was lethal to controls. No toxicity was detectable in human liver or renal cells in culture, or in livers, kidneys or spleens of pheromonicin-treated mice. The results suggest that these types of chimeric peptides may be of value as antibiotics against specific bacterial infections.

Amino Acid Sequence↗

PubMed2003

Continuous administration of antisense oligonucleotides to c-fos reduced the development of seizure susceptibility after ethacrynic acid-induced seizure in mice.

We previously demonstrated that seizure susceptibility developed by the 14th day post-ethacrynic acid (EA)-induced seizure in mice, with a prolonged increase in the expression of c-fos mRNA in the brain during days 10-14. To examine whether such c-fos increase contributes to the development of seizure susceptibility, we administered antisense oligodeoxynucleotide to c-fos by continuous infusion into the lateral ventricle of mice that had shown a moderate stage of EA seizure, and evaluated the seizure susceptibility to kainic acid (10 mg/kg) on the 14th day. Antisense-infused mice displayed significant reduction of the c-Fos level in the hippocampus and cerebral cortex on the 7th and 14th days, and a significant decrease in seizure severity. These findings suggest that the prolonged increase in c-fos expression after EA seizure may lead to the development of seizure susceptibility.

Animals↗

PubMed2003

Peroxisome proliferator-activated receptor gamma and ligands inhibit surfactant protein B gene expression in the lung.

Pulmonary nonciliated bronchiolar epithelial cells (Clara cells) and alveolar type II (AT II) epithelial cells are responsible for surfactant synthesis and secretion. These cells are highly lipogenic with a high lipid turnover rate. Although only 10% of surfactant lipids are neutral lipids, they play very important roles in maintaining pulmonary surfactant homeostasis. Many metabolic intermediate products of neutral lipids serve as ligands for various nuclear receptors that bind to target genes to influence gene transcription. In this report, the functional role of the neutral lipid metabolites, 15-deoxy-Delta12,14-prostaglandin J2 and 9-hydroxyoctadecanoic acids, and peroxisome proliferator-activated receptor gamma was evaluated in surfactant protein B gene regulation. These reagents down-regulated surfactant protein B gene expression in respiratory epithelial cells at the transcriptional level in both cell line and whole lung explant systems. The studies support the concept that surfactant protein B homeostasis is influenced by neutral lipid metabolites in the lung.

Animals↗

PubMed2003

Analysis of the herpes simplex virus type 1 UL6 gene in patients with stromal keratitis.

Recent work suggests that herpes simplex virus (HSV) stromal keratitis in the mouse is caused by autoreactive T lymphocytes triggered by a 16 amino acid region of the HSV UL6 protein (aa299-314), Science 279, 1344-1347). In the present study we sought to determine whether genetic variation of this presumed autoreactive UL6 epitope is responsible for different pathogenic patterns of human HSV keratitis. To accomplish this, we sequenced the HSV UL6 gene from ocular isolates of 10 patients with necrotizing stromal keratitis, 7 patients with recurrent epithelial keratitis, and 8 patients with other forms of HSV keratitis. The sequences obtained predicted identical UL6(299-314) epitopes for all 25 viral isolates. Furthermore, the upstream sequence of all isolates was free of insertions, deletions, and stop codons. We conclude that different pathogenic patterns of human HSV keratitis occur independent of genetic variation of the HSV UL6 (299-314) epitope.

Capsid↗

PubMed2003

Immunotherapy of tumors with vaccine based on quail homologous vascular endothelial growth factor receptor-2.

The breaking of immune tolerance of "self-antigens" associated with angiogenesis is an attractive approach to cancer therapy by active immunity. We used vascular endothelial growth factor receptor-2 (VEGFR-2) as a model antigen to explore the feasibility of the immunotherapy with a vaccine based on a xenogeneic homologous protein. To test this concept, we prepared a quail homologous VEGFR-2 protein vaccine (qVEGFR) based on quail VEGFR-2. At the same time, a protein vaccine based on the corresponding ligand-binding domain of mouse self-VEGFR-2 (mVEGFR) was also prepared and used as a control. We found that immunotherapy with qVEGFR was effective at protective and therapeutic antitumor immunity in several solid and hematopoietic tumor models in mice. Autoantibodies against mouse VEGFR-2 (Flk-1) were identified by Western blot analysis and enzyme-linked immunosorbent assay (ELISA). Anti-VEGFR antibody-producing B cells were detectable by ELISPOT. Endothelial deposition of immunoglobulins developed within tumor. VEGF-mediated endothelial cell proliferation was inhibited in vitro by immunoglobulins from qVEGFR-immunized mice. Antitumor activity was caused by the adoptive transfer of the purified immunoglobulins. Antitumor activity and production of autoantibodies against Flk-1 could be abrogated by the depletion of CD4+ T lymphocytes. Angiogenesis was apparently inhibited within the tumors, and the vascularization of alginate beads was also reduced. No marked toxicity was found in the immunized mice. The observations may provide a vaccine strategy for cancer therapy through the induction of autoimmunity against the growth factor receptor associated with angiogenesis in a cross-reaction with single xenogeneic homologous protein.

Animals↗

PubMed2003

Spinal adenosine agonist reduces c-fos and astrocyte activation in dorsal horn of rats with adjuvant-induced arthritis.

Adjuvant-induced arthritis (AIA) is a useful animal model of rheumatoid arthritis (RA). We have previously shown that stimulation of spinal adenosine A1 receptors decreases peripheral signs of AIA. In this study we show that when the final dose of adenosine A1 agonist is given 1 h prior to sacrifice the number of c-Fos positive cells evoked by the AIA in both the superficial and deep dorsal horns decreases by about 50%. In saline-treated AIA animals the increase in c-Fos expression seen in laminae I-IV was accompanied by an increase in glial fibrillary acidic protein immunoreactivity, indicative of astrocyte activation. Astrocyte activation was only partially attenuated by adenosine A1 receptor agonist treatment.

Adenosine↗

PubMed2003

Inhibition of tumor growth with a vaccine based on xenogeneic homologous fibroblast growth factor receptor-1 in mice.

Angiogenesis is important for the growth of solid tumors. The breaking of the immune tolerance against the molecule associated with angiogenesis should be a useful approach for cancer therapy. However, the immunity to self-molecules is difficult to elicit by a vaccine based on autologous or syngeneic molecules due to immune tolerance. Basic fibroblast growth factor (bFGF) is a specific and potent angiogenic factor implicated in tumor growth. The biological activity of bFGF is mediated through interaction with its high-affinity receptor, fibroblast growth factor receptor-1 (FGFR-1). In this study, we selected Xenopus FGFR-1 as a model antigen by the breaking of immune tolerance to explore the feasibility of cancer therapy in murine tumor models. We show here that vaccination with Xenopus FGFR-1 (pxFR1) is effective at antitumor immunity in three murine models. FGFR-1-specific autoantibodies in sera of pxFR1-immunized mice could be found in Western blotting analysis. The purified immunoglobulins were effective at the inhibition of endothelial cell proliferation in vitro and at the antitumor activity in vivo. The antitumor activity and production of FGFR-1-specific autoantibodies could be abrogated by depletion of CD4+ T lymphocytes. Histological examination revealed that the autoantibody was deposited on the endothelial cells within tumor tissues from pxFR1-immunized mice, and intratumoral angiogenesis was significantly suppressed. Furthermore, the inhibition of angiogenesis could also be found in alginate-encapsulate tumor cell assay. These observations may provide a new vaccine strategy for cancer therapy through the induction of autoimmunity against FGFR-1 associated with angiogenesis in a cross-reaction.

Alginates↗

PubMed2003

Immunogene therapy of tumors with vaccine based on xenogeneic epidermal growth factor receptor.

The breaking of immune tolerance against self epidermal growth factor receptor (EGFr) should be a useful approach for the treatment of receptor-positive tumors with active immunization. To test this concept, we constructed a plasmid DNA encoding extracellular domain of xenogeneic (human) EGFr (hEe-p) or corresponding control mouse EGFr (mEe-p) and empty vector (c-p). Mice immunized with hEe-p showed both protective and therapeutic antitumor activity against EGFr-positive tumor. Sera isolated from the hEe-p-immunized mice exhibited positive staining for EGFr-positive tumor cells in flow cytometric analysis and recognized a single 170-kDa band in Western blot analysis. Ig subclasses responded to rEGFr proteins were elevated in IgG1, Ig2a, and Ig2b. There was the deposition of IgG on the tumor cells. Adoptive transfer of the purified Igs showed the antitumor activity. The increased killing activity of CTL against EGFr-positive tumor cells could be blocked by anti-CD8 or anti-MHC class I mAb. In vivo depletion of CD4(+) T lymphocytes could completely abrogate the antitumor activity, whereas the depletion of CD8(+) cells showed partial abrogation. The adoptive transfer of CD4-depleted (CD8(+)) or CD8-depleted (CD4(+)) T lymphocytes isolated from mice immunized with hEe-p vaccine showed the antitumor activity. In addition, the increase in level of both IFN-gamma and IL-4 was found. Taken together, these findings may provide a new vaccine strategy for the treatment of EGFr-positive tumors through the induction of the autoimmune response against EGFr in a cross-reaction between the xenogeneic homologous and self EGFr.

Adoptive Transfer↗

PubMed2003

Active immunogene therapy of cancer with vaccine on the basis of chicken homologous matrix metalloproteinase-2.

Matrix metalloproteinase (MMP) family, in particular MMP-2, may play a key role in angiogenesis and tumor growth. It is conceivable that the breaking of immune tolerance of MMP-2 should be a useful approach to cancer therapy by active immunity. To test this concept, we constructed a plasmid DNA encoding chicken homologous MMP-2 (c-MMP-2) and control vectors. We found that the vaccine based on chicken homologous MMP-2 as a model antigen could induce both protective and therapeutic antitumor immunity. Autoantibodies against MMP-2 in sera of mice immunized with c-MMP-2 could be found by Western blotting analysis and ELISA assay. There was the deposition of autoantibodies within the tumor. IgG1 and IgG2b were substantially increased in response to c-MMP-2 immunization. The elevation of MMP-2 in the sera of tumor-bearing mice was abrogated with the vaccination of c-MMP-2. Transmigration of human endothelial cells and tumor cells through gelatin-coated filters was inhibited with immunoglobulins isolated from mice immunized with c-MMP-2. The gelatinase activity of MMP-2, including both latent MMP-2 (M(r) 72,000) and active MMP-2 (M(r) 66,000) derived from tumor tissues, was apparently inhibited by the vaccination with c-MMP-2. The antitumor activity and the inhibition of angiogenesis were acquired by the adoptive transfer of the purified immunoglobulins. The antitumor activity and production of autoantibodies against MMP-2 could be abrogated by the depletion of CD4(+) T lymphocytes. Angiogenesis was apparently inhibited within tumor, and chick CAMs angiogenesis was also inhibited. Thus, our findings may provide a vaccine strategy for cancer therapy through the induction of an autoimmune response against MMP-2 in a cross-reaction by the immunization with the single xenogeneic homologous MMP-2 gene and may be of importance in the additional exploration of the application of other xenogeneic homologous genes identified in human and other animal genome projects in cancer therapy.

Animals↗

PubMed2003

Inhibition of free radical-induced peroxidation of rat liver microsomes by resveratrol and its analogues.

Resveratrol (3,5,4'-trans-trihydroxystilbene) is a natural phytoalexin present in grapes and red wine, which possesses a variety of biological activities including antioxidative activity. To find more efficient antioxidants by structural modification, resveratrol analogues, that is, 3,4-dihydroxy-trans-stilbene (3,4-DHS), 4,4'-dihydroxy-trans-stilbene (4,4'-DHS), 4-hydroxy-trans-stilbene (4-HS) and 3,5-dihydroxy-trans-stilbene (3,5-DHS), were synthesized and their antioxidant activity studied for the free radical-induced peroxidation of rat liver microsomes in vitro. The peroxidation was initiated by either a water-soluble azo compound 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) or Fe(2+)/ascorbate, and monitored by oxygen uptake and formation of thiobarbituric acid reactive substances (TBARS). It was found that all of these trans-stilbene derivatives are effective antioxidants against both AAPH- and iron-induced peroxidation of rat liver microsomes with an activity sequence of 3,4-DHS>4,4'-DHS>resveratrol>4-HS>3,5-DHS. The remarkably higher antioxidant activity of 3,4-DHS is discussed.

Amidines↗