Biomedical subjects

P Yang

Publications and source records attributed to P Yang.

At least 127 records · Page 7Linked to original sources

PubMed2000

Antigen presenting cells expressing Fas ligand down-modulate chronic inflammatory disease in Fas ligand-deficient mice.

We assessed the effect of modified antigen presenting cells (APCs) expressing high levels of Fas ligand (APC-FasL) on post-viral chronic inflammatory disease. FasL-deficient B6-gld/gld mice infected with murine cytomegalovirus (MCMV) cleared the virus from their lungs, kidneys, and livers within 2 weeks of infection. However, inflammation persisted in these organs for more than 8 weeks, with a chronically increased T-cell response to MCMV-infected APCs and production of autoantibodies. Administration of APC-AdFasL at 4 weeks suppressed this inflammation and diminished the T-cell response and autoantibody production. APC-AdFasL that had been transfected with ultraviolet-irradiated MCMV were more effective than uninfected APC-AdFasL in ameliorating the chronic inflammation. APC-AdFasL migrated preferentially to the spleen, where they triggered apoptosis of lymphocytes in the marginal zone of the spleen. These results confirm that Fas-mediated apoptosis is not required for clearance of virus, but is required for down-modulation of the virally induced chronic inflammatory response. This organwide effect of APC-AdFasL appears to be mediated by elimination of activated T lymphocytes in the spleen before their emigration to the target organs.

Adenoviridae↗

PubMed2000

Protein phosphatases PP1 and PP2A are located in distinct positions in the Chlamydomonas flagellar axoneme.

We postulated that microcystin-sensitive protein phosphatases are integral components of the Chlamydomonas flagellar axoneme, positioned to regulate inner arm dynein activity. To test this, we took a direct biochemical approach. Microcystin-Sepharose affinity purification revealed a prominent 35-kDa axonemal protein, predicted to be the catalytic subunit of type-1 protein phosphatase (PP1c). We cloned the Chlamydomonas PP1c and produced specific polyclonal peptide antibodies. Based on western blot analysis, the 35-kDa PP1c is anchored in the axoneme. Moreover, analysis of flagella and axonemes from mutant strains revealed that PP1c is primarily, but not exclusively, anchored in the central pair apparatus, associated with the C1 microtubule. Thus, PP1 is part of the central pair mechanism that controls flagellar motility. Two additional axonemal proteins of 62 and 37 kDa were also isolated using microcystin-Sepharose affinity. Based on direct peptide sequence and western blots, these proteins are the A- and C-subunits of type 2A protein phosphatase (PP2A). The axonemal PP2A is not one of the previously identified components of the central pair apparatus, outer arm dynein, inner arm dynein, dynein regulatory complex or the radial spokes. We postulate PP2A is anchored on the doublet microtubules, possibly in position to directly control inner arm dynein activity.

Amino Acid Sequence↗

PubMed2000

Effects of third ventricle injection of norepinephrine analogue on LH secretion of the non-laying SIJI goose.

The effect of norepinephrine analogue (NA) and norepinephrine antagonists on luteinizing hormone releasing hormone (LHRH) secretion in geese was investigated by monitoring serum levels of LH. Twenty non-laying geese were selected and randomly assigned to 4 groups of 5 each. The geese received a single intraventricular injection of saline (control), NA (12 microg/6 microl), phentolamine (1 microg/6l) plus NA or yohimbine (10 microg/6 microl). Phentolamine, a non-selective adrenoreceptor blocker was given 5 min before NA, but yohimbine, an alpha2-adrenoreceptor blocker, was delivered without NA injection. The results showed that serum levels of LH began to increase 20 min after injection of NA, and that high serum levels of LH were maintained until 105 min, followed by a decline to the basal level 125 min later. Significantly high levels of serum LH were observed at 50 and 105 min after the injection as compared with the respective control. Treatment with phentolamine completely blocked the stimulatory effect of NA on serum levels of LH in NA treated geese. Serum levels of LH increased by yohimbine treatment 5 min after the injection and the high levels of serum LH were maintained until 125 min later. Five out of 8 points were significantly high as compared with their respective control values. The present study also suggested that there is presynaptic modulation in the a-noradrenergic neural pathways which mediate the release of LHRH, and that this modulation may be carried out by alpha2-adrenoreceptor blocker.

Adrenergic alpha-Agonists↗

PubMed2000

Telomerase activity and expression of apoptosis and anti-apoptosis regulators in the progression pathway of human melanoma.

The stages defining the progression pathway of human melanoma are atypical nevi, the precursor lesions and risk markers of melanoma, melanoma in situ and melanoma in the radical growth phase (RGP), which represent the early stages of melanoma development, and primary melanoma in the vertical growth phase (VGP) and melanoma in the metastatic growth phase (MGP), which are the advanced stages of the disease. Unlike cells obtained from VGP and MGP melanomas, which can be established as cell lines, cells derived from atypical nevi, melanoma in situ, and RGP melanoma cannot be propagated in vitro. Thus, information regarding molecular markers that may be differentially expressed in the early versus the advanced stages of this disease can only be obtained from the analysis of specimens. Since activation of telomerase and deregulation of apoptosis contribute to the pathogenesis of a significant number of human malignancies, we conducted a study, using nevus and melanoma specimens, to determine at what stage in the progression pathway of melanoma, telomerase activity can first be detected, and whether concordant with telomerase activation, one might observe a stage-specific switch from expression of promoters to inhibitors of apoptosis. The findings described here, demonstrate telomerase activity in some but not all MGP melanomas and not in any of the preceding pathological stages, and no apparent imbalance between pro- and anti-apoptotic markers in telomerase-positive MGP melanomas compared to telomerase-negative nevi and telomerase-negative VGP and MGP melanomas.

Apoptosis↗

PubMed2000

Alpha1-antitrypsin deficiency and inflammatory bowel diseases.

OBJECTIVE: To evaluate a possible etiologic role of alpha1-antitrypsin deficiency (alpha1AD), most frequently caused by a Z allele mutation, in ulcerative colitis (UC) and Crohn disease (CD). PATIENTS AND METHODS: This retrospective study included 10 patients diagnosed with and/or treated for inflammatory bowel disease (IBD) between 1976 and 1997 and identified from the Mayo Clinic Medical Index System. All 10 patients had either alpha1AD and CD or alpha1AD and UC. The alpha1-antitrypsin (alpha1AT) types and levels were determined with isoelectric focusing testing. The allele types, representing genotypes, were designated PiZZ (or ZZ) for homozygotes and PiMZ (or MZ) for heterozygotes. RESULTS: Seven patients had UC: 4 were genotype ZZ and 3 MZ. Four of these 7 patients had emphysema, 2 had asthma, and 1 had chronic bronchitis. Five were cigarette smokers, but only 1 had smoked coincident with activity of her UC. Two of the UC patients never smoked, and 1 of these 2 had asthma. Three of the 10 patients had CD, 2 genotype ZZ and 1 MZ. Two of the 3 patients were long-term cigarette smokers, and both had emphysema. Nine of the 10 patients with UC and alpha1AD required surgery. CONCLUSIONS: The need for surgery in patients with UC and alpha1-AD may point to a unique phenotypic subgroup of patients with alpha1AD and severe UC. Further studies are required to substantiate the etiologic role of alpha1AD in IBD. Our observations, if confirmed by future studies, suggest that in patients with both IBD and chronic obstructive pulmonary disease, alpha1AD testing should be considered.

Adult↗

PubMed2000

Localization and characterization of immunocompetent cells in the human retina.

PURPOSE: Recent studies have shown that experimental uveitis can be induced by the appropriate administration of various retinal antigens. Little is known about the in-situ interactions between immune cells in the retina as a prerequisite for understanding the mechanisms involving the presentation of antigens by local antigen-presenting cells (APC) to invading T cells. The study described here was therefore designed to investigate the presence of immunocompetent cells with a focus on the characterization of retinal APCs. MATERIALS AND METHODS: Retinal wholemounts, cytospins, and ocular sections were prepared from eyebank eyes obtained within 24 hours postmortem. Immunohistochemistry (single staining and double staining) was performed on the retinal wholemounts, cytospins, and the ocular sections using monoclonal antibodies specific for HLA-DR (MHC class II), CD45 (leukocytes), CD68 (macrophages), CD22 (B cells), CD3 (T cells), and CD1a (dendritic cells). RESULTS: CD68-positive macrophages were observed in one layer of the retina, whereas HLA-DR(+) and CD45(+) cells were seen in two distinct planes: one mainly at the level of the inner nuclear layer to outer plexiform layer (deep layer) and the other mainly at the nerve fiber and ganglion cell layer (shallow layer). There was a significant difference between the different parts of the retina with regard to the density of these cells. Cell density decreased when going from the peripheral to the posterior areas of the retina. The positive cells in the deep layer were frequently associated with blood vessels, whereas the cells in the shallow layer were distributed evenly throughout the retina. Most positive cells displayed a dendritiform appearance, whereas few cells showed a pleiomorphic morphology. Very few CD1a-positive cells were noted in the retina. Neither T cells (CD3) nor B cells (CD22) could be detected in the normal human retina. Double staining showed that the majority (83. 7%) of the CD45(+) cell population was HLA-DR-positive, whereas approximately half (56.8%) the CD68(+) cell population was HLA-DR-positive. CONCLUSIONS: This study shows that the human retina contains a number of different microglia populations, some of which express HLA-DR and could thus be involved in antigen presentation. Marked differences in cell density can be observed within the retina, with the most abundant presence seen in the peripheral retina. The normal retina contains few professional antigen-presenting cells (CD1(+)).

Adult↗

PubMed2000

[Changes of T lymphocyte and CD4+ T helper subsets in peripheral blood from women with unexplained recurrent spontaneous abortion].

OBJECTIVE: To investigate the relationship between occurrence of unexplained recurrent spontaneous abortion(URSA) and immune function of T lymphocytes. METHODS: T lymphocyte subsets and CD4+ T helper subsets (including T helper 1 and T helper 2 cells) in peripheral blood from 30 cases with URSA and 24 healthy women (controls) were detected by enzyme-linked immunospot assay (ELISPOT). RESULTS: The percentage of CD4+ positive T lymphocytes in URSA group was higher than that in the controls (60% vs 45%, P < 0.05). Compared with the normal group, the percentage of Th1 cells increased (26% vs 14%, P < 0.01) but the percentage of Th2 cells decreased (7% vs 20%, P < 0.05), the ratio of Th1 to Th2 increased (3.80 vs 0.73, P < 0.01) in the URSA group. CONCLUSIONS: The occurrence of URSA might be associated with proliferation of the CD4+ positive T cells and enhancement of cellular immune function mediated by Th1 cells.

Abortion, Habitual↗

PubMed2000

[Sequence analysis of the 5' and 3' terminal regions of dengue type 2 virus 04 strain].

OBJECTIVE: To analyze the sequences of 5' and 3' terminal region of dengue type 2 virus 04 strain. METHODS: Total RNA was isolated from dengue type 2 virus 04 strain (D2-04) infected C6/36 cells. With this RNA as template, the cDNA of both 5' and 3' termini of D2-04 were amplified using RACE method respectively. The cDNAs were separately inserted into pGEM-T vector and the recombinant plasmids containing the 5' terminus 535 bp and 3' terminus 503 bp were obtained. The nucleotide sequences of the inserted cDNA fragment were determined. The nucleotide sequences of the 5' and 3' noncoding regions of D2-04 were compared with other dengue type 2 viruses such as JAM, NGC, S1, 16681 and PD-53. RESULTS: The results showed that they shared 98.96%, 98.96%, 93.75%, 98.95%, 97.92% and 97.72%, 97.80%, 90.65%, 94.26%, 94.22% homology with D2-04 strain respectively. CONCLUSIONS: Except SI, the homology between D2-04 and other type 2 viruses was higher than 94%.

Base Sequence↗

PubMed2000

[Analysis of complications of augmentation mammaplasty in 12 patients].

OBJECTIVE: To reduce complications and to improve the long-term results of augmentation mammaplasty. METHOD: Twelve patients who had complications during a period of 1 to 13 years after augmentation mammaplasty were studied. The fibrous capsule of the breast implant was examined pathologically. RESULTS: 12 patients (15 breasts) were included in the study. Of the nine patients with unilateral augmentation mammaplasty, four had 1 complication; four had 2 complications and one had 3 complications. Of the three patients with bilateral augmentation mammaplasty, two had the same complication, one had 3 complications. Every complication has its pathologic and clinical characteristics. CONCLUSION: Many measures are important for reducing complications including strict surgical manipulation, proper selection of good implants, preferred submuscular insertion, whole capsulectomy for prosthesis rupture or leak and through hemostasis, proper bandage, massage and follow-up et al.

Adult↗

PubMed2000

[Ehancement of tissue expansion in guinea pig by local delivery of chemical agents using a new type expander].

OBJECTIVE: To search for the new method to increase the rate of tissue expansion. METHODS: A new type of double-lumen expander was buried in the back of guinea pig. Through the expander chemical agents (papaverine) were delivered. RESULTS: The new expander could effectively deliver chemical agents. In comparison with the control group, the blood flow, survival length and the length to width ratio of the expanded flap in the experimental group increased statistically. The immediate retraction ratio of the flap decreased significantly. The epidermis was thicker while the dermis was not significant different from the control. The panniculus carnosus was significant thinner in the expanded group than the unexpanded group. The deep connective tissue was statistically thinner in the group using the new type expander. CONCLUSION: The new type of expansion method could accelerate tissue expansion rate and improve the quality of expanded skin and flap.

Animals↗

PubMed2000

Effect of superantigen on ion electrophysiology and permeability in rabbit maxillary sinus epithelia.

OBJECTIVE: Superantigens are potent inflammatory stimuli which derive from pathogenic microbes such as bacteria, viruses and protozoa. The aim of this study was to investigate the role of superantigens on the function of rabbit maxillary sinus epithelium. METHODS: Twenty New Zealand white rabbits were divided into 4 groups. Rabbit sinus mucosa was separated under a surgical microscope and mounted in Ussing chambers to record short circuit current, conductance and permeability to horseradish peroxidase (HRP). Group A was used as normal control. Group B was stimulated with an injection of superantigen into the sinus for 4 hours. The sinus mucosa of Group C was stimulated by the addition of tumor necrosis factor alpha (TNF-alpha) into Ussing chambers. Group D sinus mucosa was stimulated by superantigen after pretreatment with anti-TNF-alpha antibody. RESULTS: Superantigen evoked increases in sinus epithelial cell baseline short circuit current, conductance and permeability to HRP stimulated by the addition of TNF-alpha into Ussing chambers. These were similar to results from superantigen stimulation in vivo. The effect of superantigen on sinus epithelial cells could be blocked by pretreatment with anti-TNF-alpha antibody. CONCLUSIONS: Superantigen affected the function of sinus epithelial cells, including the capability of epithelial defensive barrier, which might be mediated by TNF-alpha.

Animals↗

PubMed2000

Apoptosis of infiltrating cells in experimental autoimmune uveoretinitis.

OBJECTIVE: To investigate the cellular phenotype and apoptosis of infiltrating cells involved in experimental autoimmune uveoretinitis (EAU). METHODS: Immunohistochemical staining and in situ apoptosis staining were performed using monoclonal antibodies to monocytes and macrophages (ED1), major histocompatibility complex (MHC) class-II antigen (OX6), T lymphocytes (R73) and TACS 1 Klenow kit on both ocular sections and wholemounts from Lewis rats after immunization with interphotoreceptor retinoid-binding protein (IRBP). RESULTS: EAU was induced in 12 of 16 Lewis rats with a mean clinical inflammation score of 1.29 +/- 0.7. Influx of monocytes, lymphocytes and MHC class II-positive cells into the uvea and retina was noted after immunization with IRBP. Apoptosis of infiltrating cells was observed in the uvea and retina, and more apoptotic cells were present in the iris and ciliary body compared with those in the choroid and retina. CONCLUSION: Apoptosis of infiltrating cells occurs at the early stage of EAU, which may greatly contribute to the rapid regression of the inflammation induced by IRBP.

Animals↗

PubMed2000

[The study of histopathology and bacteriology of coronal pulp tissue in deciduous teeth with deep dentin caries].

OBJECTIVE: To study the status of coronal pulp of deciduous teeth with deep caries and causes of pulpal histopathological changes. METHODS: 45 deciduous molars with occlusal deep caries were selected at random. The patients did not receive any antibiotic for one month. The coronal pulpal histopathology was observed with optical microscopic technique. The bacteria in pulp chamber were cultured by the ways of aerobic and anaerobic culture technique. The dentinal tubular structures and bacteria within the tubules of cavity basal part dentin were studied with scanning electron microscopic technique. RESULTS: Coronal pulp tissue of 77.8% of deciduous teeth with deep caries showed chronic inflammation to various degrees or chronic pulpitis with acute attack. There were aerobic and anaerobic mixed infection in pulp chambers of 94.9% deciduous teeth with deep caries. It was found that coccus and bacillus invaded into dentinal tubules of cavity basal part. Coccus located inside tubules with intact tubular walls, while tubular walls were destroyed the bacillus was present. CONCLUSION: There are aerobic and anaerobic mixed infection in pulp chamber of deciduous teeth with deep caries. The coronal pulp tissue shows chronic inflammation to various extent in over 2/3 deciduous teeth with deep caries. Bacillus has stronger destructive power to dental tubules.

Child↗

PubMed2000

[Immunologic experimental studies on the alkali burn of cornea in rats].

OBJECTIVE: To investigate the immune reaction of severe corneal alkali burns. METHODS: The models of severe corneal alkali burns were induced in rats. Immunohistochemistry was carried out on wholemounts of the cornea and iris at different time points after corneal burns to detect T-lymphocytes and their subpopulation, macrophages, dendritic cells and MHC class II -positive cells. RESULTS: In the early stage of the burns, there were small increasing number of T-lymphocytes and MHC class II-positive cells in the cornea and iris. At the period of corneal melting and perforation, a massive influx of lymphocytes (CD(+)(3), CD(+)(4), CD(+)(8)), macrophages and dendritic cells was seen in the cornea adjacent to the limbus and iris. CD(+)(4) lymphocytes were much more than CD(+)(8) in number. T-cells and MHC class II-positive cells were observed not only at the limbus but also in the melting area and corneal center. Morphological changes of these cells were also noted. In the restoration stage, a number of positive cells were still found in the iris. CONCLUSION: Immunological mechanism is involved in the pathological changes of the damage induced by corneal alkali burns, especially in the pathogenesis of the corneal melting and perforation.

Alkalies↗

PubMed2000

[Study of the distribution feature of the endocrine cells of human islet and its relation to microvasculature].

Double immunohistochemical stain was used for the study of distribution feature of the endocrine cells of human islets and its relation to the microvasculature. The results were as follows (1) Sheath islet was found in human adult islets and the B cells situated the central part of the islets and arrounding it were the A and D cells which formed the sheath of the islets. (2) The identical distribution of the A and D cells was found. (3) Some islets were divided into several "subunite" by connective tissue in which the B cells and A(or D) cells situated the central and peripheral part respectively. (4) The A and D cells were near the microvasculature. These results will provide morphologic basis for the research of the functional relation among the endocrine cells.

Humans↗

PubMed2000

[Studies on biosorption of Au3+ by Bacillus megaterium].

Some characteristics of Au3+ biosorption and bioreduction by Bacillus megaterium D01 biomass were reported. The optimum pH value of Au3+ biosorption by strain D01 was 3.0. The biosorption was a rapid process, reaching 95% of the maximal capacity within the first 5 min of contact. Temperature did not affect the biosorption. The biosorptive efficiency(99.1%) and capacity (302.0 mg Au3+/g dry weight biomass) were achieved under the conditions of pH 3.0 and 30 degrees C, both concentration with an initial Au3+/biomass radio of 305 mg/g dry weight for 30 min of the contact. The D01 biomass could reduce Au3+ in the solution to Au0, Au0 on the cells surface and in the contact solution could be crystallized to different forms gold crystals, Au3+ impregnated on SiO2 and alpha-Fe2O3 could be reduced to Au0 by D01 biomass. The results of electrochemical reaction indicated that the strain D01 exhibited a high selectivity for Au3+.

Adsorption↗

PubMed2000

[Transgenic mice model of human hepatitis B virus x gene].

OBJECTIVE: To set up a human hepatitis B virus x (HBx) gene transgenic model. METHODS: The model was set up by microinjection, the integration and expression of the founders were identified by molecular hybridization. RESULTS: A 1,800 bp DNA fragment containing the human HBx promoter and genomic DNA was microinjected into the male pronucleus of the fertilized eggs of mice. Three hundred and thirty-eight eggs survived from microinjection were transplanted into the oviduct of 16 pseudopregnant female, 12 pseudopregnant mice got pregnant and gave birth to 74 pups. Genomic DNA were extracted from the tails of the pups, Southern blot hybridization was used for determination of the integration of human HBx gene. The 1,800 bp microinjected fragment was used as the probe, 17 mice (founders) were identified of the integration of human HBx gene. Total RNA were extracted from the livers of the founders, all 17 founders were identified of the expression of human HBx gene by using Northern blot hybridization. CONCLUSIONS: These results may provide animal models for studying on the correlation between chronic HBV infection and the development of hepatocellular carcinoma.

Animals↗

PubMed2000

[Photoluminescence characteristics of mixed aggregates in Langmuir-Blodgett multilayers].

Effects of the mixed aggregates of different active molecules and UV illumination on photoluminescence(PL) spectra of Langmuir-Blodgett multilayers were investigated. The strong interaction between hemicyanine and stilbazolium salt molecules in the mixed films caused a blue or red shift of the fluorescence band with respect to that of interleaving hemicyanine or stilbazolium salt/arachidic acid multilayers. UV illumination would dissociate the aggregates even more destroy the molecular structure, leading to a significant reduction of fluorescence intensity.

English Abstract↗