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Biomedical subjects

Z Peng

Publications and source records attributed to Z Peng.

At least 19 recordsLinked to original sources
PubMed2001

CpG oligodeoxynucleotide vaccination suppresses IgE induction but may fail to down-regulate ongoing IgE responses in mice.

Antigen-specific IgE plays an important role in the pathogenesis of allergic disorders. Immunostimulatory CpG motifs (CpG) in bacterial DNA or synthesized oligodeoxynucleotides (ODN) are gaining recognition as potential immunomodulators for switching on protectiveT(h)1-mediated immunity and preventing or potentially inhibiting T(h)2-dependent allergic responses. To date, allergic models used in CpG ODN studies have been established by immunization of mice with allergen in the presence of adjuvant. This, in addition to failure to assess specific IgE production in most of the studies, has limited understanding of the role of CpG ODN vaccination in allergic responses. Here, we examine the effects of synthesized CpG ODN on both developing and ongoing IgE responses in mice sensitized using a recombinant mosquito salivary antigen (rAed a 2) without adjuvant. Pretreatment of mice with CpG ODN mixed with rAed a 2 successfully inhibited subsequent induction of serum rAed a 2-specific IgE (but not IgG1) and antigen-induced IL-4 and IL-5 production in spleen cells. This was associated with an increase of serum IgG2a and IL-12, and increased IFN-gamma and IL-12 production by spleen cells. In this model, however, co-administration of CpG ODN with rAed a 2 to presensitized mice failed to down-regulate ongoing IgE responses despite significant up-regulation of serum IL-12 and specific IgG2a. Strikingly, a transient skin delayed-type hypersensitivity reaction occurred in CpG ODN-treated mice. These observations provide a new insight into the potential therapeutic application of CpG ODN to allergic disorders.

Adjuvants, Immunologic↗
PubMed2000

Interferon-gamma-responsive neuronal sites in the normal rat brain: receptor protein distribution and cell activation revealed by Fos induction.

Constitutive expression of the interferon-gamma receptor protein (IFN-gammaR), and the distribution of cells in which Fos, a marker of cell activation, is induced by intracerebroventricular administration of IFN-gamma, were studied in the rat brain by immunohistochemistry. IFN-gammaR immunopositivity was found in neuronal elements, which exhibited a selective distribution being concentrated in the piriform and entorhinal cortex, midline thalamus and medial hypothalamic structures, brainstem nociceptive relays (including the periaqueductal gray, the parabrachial nuclei and the caudal part of the spinal trigeminal nuclei), and circumventricular organs such as the median eminence and area postrema. IFN-gamma-induced Fos expression mostly corresponded to neuronal sites of receptor distribution. Because of its topographical distribution, it is suggested that activation of the IFN-gammaR in neurons may play a role to limit spread of infections in the brain and, in concert with other proinflammatory cytokines, to modulate adaptive responses to an antigen challenge mediated by the central nervous system.

Animals↗
PubMed2000

Hierarchical unfolding of the alpha-lactalbumin molten globule: presence of a compact intermediate without a unique tertiary fold.

The difference between the framework model and the hydrophobic collapse model of protein folding largely rests on whether a secondary-structure framework can exist independently of native tertiary interactions. Here, we used circular dichroism and disulfide exchange experiments to examine the unfolding mechanism of alpha-LA(alpha), a two- disulfide variant of human alpha-lactalbumin (alpha-LA) that adopts a molten globule conformation under near physiological conditions. Our results show that as the concentration of denaturant increases, the alpha-LA molten globule first loses its ability to form a specific, native-like tertiary fold. Subsequently, at a higher denaturant concentration, the protein loses its secondary structure and adopts an extended conformation. A compact, non-native disulfide bond isomer, which does not form significantly under both native and strongly denaturing conditions, was found to be moderately populated in approximately 2 M guanidine hydrochloride (GuHCl). Qualitatively the same result was also obtained in urea. These results suggest that formation of secondary structure is a necessary, but not sufficient condition for formation of the native-like tertiary fold and support a hierarchical model of protein folding.

Amino Acid Substitution↗
PubMed2000

Cloning and overexpression of a tyrosinase gene mel from Pseudomonas maltophila.

The tyrosinase gene (mel), which is responsible for melanin formation, was isolated by shotgun cloning of SalI fragments of Pseudomonas maltophila DNA. A 0.7-kb SalI fragment in the recombinant plasmid pWSY8 imparted the ability to synthesize melanin to an Escherichia coli host HB101. The nucleotide sequence of this DNA fragment revealed an open reading frame of 504 bp, encoding a protein of 169 amino acids. The fragment containing the mel gene was then cloned into an expression plasmid pPAS1 under the control of a promoter isolated from the host, P. maltophilia AT18. This strain increased the melanin production by 70.6% compared with the strain HB101/pWSY8, in which the cloned mel gene was under the control of the lac promoter from the vector pUC18.

Amino Acid Sequence↗
PubMed2000

Analysis of diversity and genetic relationships between four Chinese indigenous pig breeds and one Australian commercial pig breed.

The genetic diversities and relationships of four Chinese indigenous pig breeds and one Australian commercial pig breed have been evaluated using 27 microsatellites recommended by the International Society of Animal Genetics (ISAG) and the Food and Agriculture Organization (FAO). The allele frequencies, effective numbers of alleles and the polymorphic information content have been calculated. Nei's standard genetic distances have been used to construct a UPGMA dendrogram, which has been evaluated by the Bootstrap test. The utility of microsatellites for evaluating genetic diversity of pigs is discussed.

Alleles↗
PubMed2000

Ordering three microsatellites on porcine chromosome 12 by single sperm typing.

Three microsatellite loci on porcine chromosome 12 were ordered by single sperm typing to expand the limited genetic map of this region. Individual sperm cells from a Chinese indigenous Qingping boar triply heterozygous at SW874, SW1350 and SW1553 were amplified using PEP and heminesting primer design at each locus. Analysis of the sperm typing data by the SPERM.FOR program showed that the most likely order was SW1553-SW1350-SW874.

Animals↗
PubMed2000

Molecular regulation of constitutive expression of interleukin-8 in human pancreatic adenocarcinoma.

Recent studies have shown that interleukin-8 (IL-8) plays an important role in the growth and metastasis of human pancreatic cancer. In the present study, we determined the molecular regulation of constitutive IL-8 expression in human pancreatic cancer cells. Various human pancreatic cancer cell lines were incubated in vitro. Sixty-seven percent of the cell lines constitutively secreted high levels of IL-8, as determined using enzyme-linked immunosorbent assay. Consistently, these cells constitutively expressed high levels of IL-8 mRNA, as determined using Northern blot analysis. To determine the mechanisms of the high steady-state levels of IL-8 mRNA, the IL-8 half-life and transcription rate were measured. There was no significant difference in IL-8 half-life between cells expressing high and low levels of IL-8. However, higher transcription rates and increased IL-8 promoter activity were observed in the cells constitutively expressing high levels of IL-8. Detailed IL-8 promoter analysis using deletion mutation revealed that the region from -85 to -133 bp was essential for the constitutive IL-8 promoter activity. Also, point-mutation analysis indicated that mutation of NF-kappaB, AP-1, or NF-IL-6 binding sites significantly reduced or eliminated the constitutive IL-8 promoter activity. Consistent with the constitutive IL-8 transcription activity, high levels of constitutive NF-kappaB and AP-1 activity were detected in the cells overexpressing IL-8, as determined using electrophoretic mobility shift assay. In addition, transfection of a dominant-negative I-kappaBalpha expression vector (I-kappaBalphaM) inhibited constitutive NF-kappaB activity and IL-8 expression in pancreatic cancer cells. Collectively, our data demonstrated that constitutive NF-kappaB and AP-1 activation contributes to the overexpression of IL-8, which in turn plays an important role in tumor angiogenesis and contributes to the aggressive biology of human pancreatic cancer.

Adenocarcinoma↗
PubMed2000

Non-penetrating chest blows and sudden death in the young.

Sudden death in the young after low energy anterior chest wall impact is an under-recognised phenomenon in this country. Review of the literature yields several American references to commotio cordis, mainly in the context of sporting events. Two cases are reported of sudden death in young men as a result of blunt impact anterior chest wall trauma. It is suggested that these cases draw attention to a lethal condition of which many practitioners are unaware.

Adolescent↗
PubMed2000

Selective estrogenic effects of a novel triphenylethylene compound, FC1271a, on bone, cholesterol level, and reproductive tissues in intact and ovariectomized rats.

FC1271a is a novel triphenylethylene compound with a tissue-selective profile of estrogen agonistic and weak antagonistic effects. It specifically binds to the estrogen receptor alpha and beta with affinity closely similar to that of toremifene and tamoxifen. To study the in vivo effects of the compound, 4-month-old rats were sham operated (sham) or ovariectomized (OVX) and treated daily for 4 weeks with various doses of FC1271a or vehicle (orally). FC1271a was able to oppose OVX-induced bone loss by maintaining the trabecular bone volume of the distal femur. Accordingly, the OVX-induced loss of bone strength was prevented at doses of 1 and 10 mg/kg. FC1271a also prevented the OVX-induced increase in serum cholesterol in a dose-dependent manner. No significant changes in uterine wet weight or morphology were observed in the OVX-rats treated with 0.1 or 1 mg/kg FC1271a, but at a dose of 10 mg/kg it had a slightly estrogenic effect. In immature rats the effect of FC1271a on uterine wet weight was less stimulatory than that of toremifene or tamoxifen, but more stimulatory than that of raloxifene or droloxifene. The appearance of the dimethylbenzanthracene (DMBA)-induced mammary tumors was inhibited by treatment of DMBA-treated rats with FC1271a in a dose-dependent manner. In human MCF-7 breast cancer cell tumors raised in nude mice in the presence of estrogen, the growth and expression of pS2 marker gene could not be maintained after estrogen withdrawal by treatment with FC1271a. No formation of DNA adducts was observed in the liver of the FC1271a-treated rats. In conclusion, the bone-sparing, antitumor, and cholesterol-lowering effects of FC1271a combined with a low uterotropic activity and lack of liver toxicity indicate that FC1271a could be an important alternative in planning antiosteoporosis therapy for estrogen deficiency.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2000

[Induction of apoptosis in ovarian carcinoma cells by HSP70 antisense oligodeoxynucleotides].

OBJECTIVE: To investigate the role of HSP70 in the proliferation and survival of ovarian carcinoma cells by inhibiting HSP70 expression with HSP70 antisense oligomer. METHODS: Morphological changes of apoptotic cells were investigated by light microscopy. DNA fragmentation was analysed by agarose gel electrophoresis. Kinetics of induction of apoptosis and cell cycle were analysed by flow cytometry. RESULTS: The HSP70 antisense oligomer treated ovarian carcinoma cells showed apparent inhibition of proliferation and characteristic morphological changes of apoptosis. Also, a ladder-like pattern of DNA fragments was demonstrated on agarose gel electrophoresis. HSP70 antisense-oligomer induced apoptosis of ovarian carcinoma cells mainly in G(1)/S phase in 8.3% to 41% at 1 to 20micromol/L. The apoptosis-inducting effect of HSP70 antisense oligomer was in a dose- and time-dependent manner. CONCLUSION: HSP70 antisense oligomer could not only inhibit the proliferation but also induce the apoptosis in ovarian carcinoma cells.

Apoptosis↗
PubMed2000

Progress in the molecular genetic research of multinodular goiter.

Multinodular goiter is a worldwide-distributed disease, but yet its pathology and genetic etiology are not clear. At present, most researches have been restrained to traditional epidemiological survey and the disease has been rarely studied at the level of molecular genetics. The pathogenesis of multinodular goiter, as is generally accepted by most researchers, can be attributed to many factors such as hormones, growth factors and the inherent functional heterogeneity of thyroid follicles. Since hormone and iodine metabolization are widely recognized as a major mechanism in determining the formation of multinodular goiter, some reports in literature are mainly focused on such genes that are responsible for hormone synthesis and iodine metabolization. Mapping experimental data were available to support location of multinodular goiter gene(s) onto chromosome 14q by whole genome scanning in a large pedigree analysis. Additional data, particularly those extracted from large scaled marker-assisted mapping experiments, are important so as to confirm the gene location, to improve resolution of the location, and finally to dissect the genes underlying the disease at molecular level.

Chromosome Mapping↗
PubMed1999

Production and characterization of monoclonal antibodies to two new mosquito Aedes aegypti salivary proteins.

Mosquito salivary proteins, which are fundamental to the process of blood feeding, also facilitate disease transmission and cause allergic reactions. The identification and characterisation of these proteins have been hampered by the difficulty of obtaining them in purified form. In this report, we describe the production of mouse monoclonal antibodies (mAbs) against mosquito salivary proteins. BALB/c mice were immunised with Aedes aegypti saliva proteins. Hybridomas were produced by fusion of spleen cells with a mouse myeloma cell line. Positive clones were selected using a saliva-capture ELISA and further identified using immunoblotting. Three mAbs reacted with a 44 kDa protein (Aed a X1) in the saliva-immunoblotting, and did not react with 2 recombinant salivary proteins, rAed a 1 (apyrase) and rAed a 2 (D7), in both immunoblotting and ELISA. Two other mAbs reacted with a 37 kDa protein in saliva-immunoblotting, but failed to react with the 37 kDa rAed a 2 in either immunoblotting or ELISA, suggesting that there is a second 37 kDa protein (Aed a X2) which is recognised by the two mAbs. The 44 kDa and 37 kDa proteins have not been previously identified. These mAbs provide a means to purify proteins, to isolate new genes from the salivary gland cDNA library, and to standardise mosquito extracts, facilitating studies of disease transmission by mosquitoes and of mosquito allergy.

Aedes↗
PubMed1999

Induction of IgE responses using a recombinant mosquito salivary allergen rAed a 2 without adjuvant in mice.

BACKGROUND: Reactions to mosquito bites are a global problem. Several salivary proteins from Aedes (Ae.) aegypti, the most common mosquito species, have been cloned and expressed. Plasmid DNA vaccination has been shown to be effective in the downregulation of IgE responses. To investigate the in vivo antigenicity of these recombinant proteins and to study the mechanisms underlying plasmid DNA vaccination, a mouse model sensitized with a recombinant antigen has been developed. METHODS: BALB/c and C57BL/6 mice were injected intradermally with a 37-kD recombinant Ae. aegypti salivary allergen (rAed a 2) in the absence of adjuvant twice weekly for 8 weeks and then challenged twice with rAed a 2 at weeks 10 and 12. Serum rAed a 2-specific IgE, IgG1 and IgG2a were measured by ELISA. Intradermal tests were performed every 4 weeks. The binding capacity of rAed a 2-specific IgE to the native Aed a 2 was examined by immunoblotting. RESULTS: In both strains, sensitization with rAed a 2 induced a significant increase in IgE and IgG1, but not IgG2a. In all sensitized mice, a positive immediate skin reaction was apparent, while delayed-type hypersensitivity reactions were not observed. BALB/c mice produced significantly higher levels of IgE and IgG1 and larger wheals than C57BL/6 mice. The IgE antibodies elicited by rAed a 2 bound to not only rAed a 2 but also its natural form in mosquito saliva. CONCLUSION: (1) Repeated injections of rAed a 2 without adjuvant induce predominant Th2-type responses in mice. (2) BALB/c mice are better responders for IgE production than C57BL/6 mice. (3) rAed a 2 has identical allergenicity to its natural form.

Adjuvants, Immunologic↗
PubMed1999

Alteration in the mechanical competence and structural properties in the femoral neck and vertebrae of ovariectomized rats.

The structural and mechanical properties of bone in the femoral neck and various other sites were investigated in intact (INT), sham-operated (Sham), and ovariectomized (OVX) rats. Six weeks after operation, the maximal load and energy absorption of the femoral neck were significantly lower in the OVX than in the INT or Sham groups, being 73.2 +/- 1.4 (SE) N, 86.3 +/- 4.1 N, and 87.1 +/- 3.2 N, respectively (p < 0.01) for load. The total cross-sectional area of the femoral neck did not change after OVX, but the marrow cavity area was enlarged, leading to a reduced bone area (including both cortical and trabecular bone) (p < 0.01). Histomorphometric analysis showed that new bone formation could not be detected at the periosteum of the femoral neck below the femoral head, but at the endocortical surfaces the double tetracycline labeling revealed an increased mineral apposition rate (MAR) and bone formation rate (BFR) in OVX animals (p < 0.001). In contrast, MAR and BFR were significantly increased in both periosteal and endocortical surfaces of the tibia, humerus, and femoral shaft, thus preventing a decrease in cortical bone area. The maximal bending loads of the tibia and humerus were not different in the various groups of animals. The correlation coefficient between maximal load and bone area revealed positive relationships in the femoral neck (r = 0.54, p < 0.01), tibia (r = 0.46, p < 0.01), and humerus (r = 0.51, p < 0.01). Ovariectomy resulted in a decreased trabecular bone volume of lumbar vertebra VI (L6) decreased compressive loads of lumbar vertebrae I, III, and IV. These lumbar bone loads were positively related to their L6 bone area (L4/L6: r = 0.66, p < 0.001). Element analyses (energy dispersion spectrometer) from trabecular and cortical areas of bone showed some changes related to aging but not to OVX. These results indicate that ovariectomy influences the biomechanical properties of rat bone by changing structural properties rather than material ones.

Animals↗
PubMed1999

[Comparative study of HLA-DRB1 allele in patients with chronic bronchitis and bronchial asthma].

OBJECTIVE: To make a comparative study of HLA-DRB1 allele frequencies in the cases of chronic bronchitis and bronchial asthma. METHODS: The authors investigated 74 patients with chronic bronchitis and 64 patients with bronchial asthma from among the Han people in Shanxi province. PCR/SSP technique was used for HLA-DRB1 typing, and the patients' data were compared with the normal controls'. RESULTS: The frequency of HLA-DRB1*1201/1202(24.32%) was significantly increased in the chronic bronchitis group(P<0.01),and the frequency of HLA-DRB1*1501/1502(23.44%) was significantly increased in the bronchial asthma group(P<0.05). The frequencies of other DRB1 alleles were not significantly increased in these groups. CONCLUSION: The results indicate that HLA-DRB1*1201/1202 allele is associated with chronic bronchitis and HLA-DRB1*1501/1502 allele is associated with bronchial asthma in the patients among the Hans in Shanxi province.

Alleles↗
PubMed1998

Immunoblot analysis of salivary allergens in 10 mosquito species with worldwide distribution and the human IgE responses to these allergens.

BACKGROUND: Most people develop skin reactions to mosquito bites, however, little is known about mosquito salivary allergens and the IgE responses to them. OBJECTIVES: We sought to identify these allergens and the specific IgE responses they elicit. METHODS: Saliva or salivary gland extracts were prepared from 10 mosquito species, including seven species with worldwide distribution: Aedes (Ae.) aegypti, Ae. vexans, Ae. albopictus, Ae. togoi, Ae. triseriatus, Culex (Cx.) quinquefasciatus, Cx. pipiens, Cx. tarsalis, Anopheles (An.) sinensis, and Culiseta (Cs.) inornata. Proteins from these preparations were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose membranes, which were immunoblotted by sequential incubations with human serum, monoclonal anti-human IgE, and enzyme-conjugated goat anti-mouse IgG. Salivary allergens were analyzed by using a pooled serum from subjects allergic to mosquitos. Individual IgE responses to each allergen were evaluated in 12 subjects allergic to mosquitos living in Canada, the United States, and China, as well as in five subjects not allergic to mosquito bites. To study species-shared allergens, the membranes were immunoblotted with two rabbit antibodies specific to recombinant mosquito salivary proteins. RESULTS: Three to sixteen salivary allergens with molecular masses ranging from 16 to 95 kd were found in each species. Both species-shared and species-specific allergens were identified by molecular masses, binding to the two rabbit antibodies, and individual IgE responses to species indigenous to and absent from the regions where the subjects lived. Salivary allergens, especially from Ae. aegypti, Ae. vexans, and Ae. albopictus, elicited higher IgE responses in subjects allergic to mosquitos than in nonallergic subjects. CONCLUSIONS: Species-shared and species-specific allergens that cause IgE responses in subjects allergic to mosquitos are immunologically identified. Species-shared allergens are the most important for potential use in diagnosis and immunotherapy.

Allergens↗