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Biomedical subjects

Z Peng

Publications and source records attributed to Z Peng.

At least 127 records · Page 7Linked to original sources
PubMed1997

[Relationship between human papillomavirus E7 protein and Rb gene product in fresh tissues of squamous cervical carcinoma].

OBJECTIVE: To study the possibility of complex formation of the E7 protein encoded by human papillomavirus (HPV) binding to retinoblastoma gene product (pRb) in fresh samples of squamous cervical carcinoma (SCC). METHODS: HPV 6/11, 16, 18, 33 DNA were detected in 40 samples of by polymerase chain reaction technique (PCR). The complexes of HPV E7-pRb were examined in fresh tissues of HPV contained SCC through capture enzyme linked immunosorbent assay (capture-ELISA). RESULTS: 45.0% (18/40) of the samples were proved to be HPV positive by PCR. Out of 18 samples with HPV positive samples, the complexes of HPV E7-pRb were detected in 9 cses, including 1 HPV18 positive and 8 HPV16 positives. The complexes of HPV E7-pRb were not found in 2 cases of positive HPV 6/11. No correlation was observed between the E7 protein binding to pRb and the histological grade of cervical carcinoma (P < 0.05). There was correlation with clinical staging, the number of cases showing that the E7 protein pRb complex in stage I was significantly higher than that in stages II-IV (P < 0.05). CONCLUSIONS: The complex of "high risk" HPV E7-pRb was demonstrated in fresh tissues of SCC. There is no correlation between the complex and histological grade of SCC. The complex formation may occur in the early developmental stage of cervical cancer.

Carcinoma, Squamous Cell↗
PubMed1996

Reciprocal regulation of delta 1-pyrroline-5-carboxylate synthetase and proline dehydrogenase genes controls proline levels during and after osmotic stress in plants.

Plants generally accumulate free proline under osmotic stress conditions. Upon removal of the osmotic stress, the proline levels return to normal. In order to understand the mechanisms involved in regulating the levels of proline, we cloned and characterized a proline dehydrogenase (PDH) cDNA from Arabidopsis thaliana (AtPDH). The 1745 bp cDNA contains a major open reading frame encoding a peptide of 499 amino acids. The deduced amino acid sequence has high homology with both Saccharomyces cerevisiae and Drosophila melanogaster proline oxidases and contains a putative mitochondrial targeting sequence. When expressed in yeast, the AtPDH cDNA complemented a yeast put1 mutation and exhibited proline oxidase activity. We also determined the free proline contents and the delta 1-pyrroline-5-carboxylate synthetase (P5CS) and PDH mRNA levels under different osmotic stress and recovery conditions. The results demonstrated that the removal of free proline during the recovery from salinity or dehydration stress involves an induction of the PDH gene while the activity of P5CS declines. The reciprocal regulation of P5CS and PDH genes appears to be a key mechanism in the control of the levels of proline during and after osmotic stress. The PDH gene was also significantly induced by exogenously applied proline. The induction of PDH by proline, however, was inhibited by salt stress.

1-Pyrroline-5-Carboxylate Dehydrogenase↗
PubMed1996

Defective folding of mutant p16(INK4) proteins encoded by tumor-derived alleles.

p16(INK4) is a specific cyclin D-dependent kinase inhibitor and a multiple tumor suppressor. Inactivation of p16 is frequent in both primary tumors and tumor-derived cell lines. We describe here the conformational properties and oligomerization state of seven mutant p16 proteins; all of them are deficient in function. Four of the seven proteins show significantly disrupted secondary structure and backbone folding. The other three adopt partially folded, molten globule-like conformations. These proteins have near-native levels of secondary structure, but lack the ability to undergo a cooperative thermal transition and are substantially less resistant to proteolysis than is wild type p16. At low concentrations, two of the seven proteins are monomers, three exhibit an apparent molecular weight between the value of a monomer and a dimer, and the other two aggregate significantly. Our results strongly suggest that defective protein folding and/or aggregation is a common mechanism for inactivation of p16.

Alleles↗
PubMed1996

Antenatal screening and fetal diagnosis of beta-thalassemia in a Chinese population: prevalence of the beta-thalassemia trait in the Guangzhou area of China.

In this paper beta-globin gene mutations were detected in 452 beta-thalassemia carriers from 13462 unselected individuals (6731 pregnant women and their husbands) who were screened for the beta-thalassemia trait in the Guangzhou area of China. The incidence of beta-thalassemia was calculated as 3.36%. This is higher than found in previous studies performed in southern China. Using reverse dot blot analysis, we found 11 types of mutations and identified the mutations in 446 (98.7%) of the 452 cases. Direct sequencing was carried out on the 6 unknown alleles, and a novel amber mutation in a beta 0-thalassemia gene (beta 37TGG --> TAG) was found in one of them. Thus, the prevalence and spectrum of beta-thalassemia mutations were obtained for this region. Twelve couples were detected at risk for thalassemia, and prenatal diagnosis was carried out in 11 of them. This is the largest number of Chinese subjects studied by DNA analysis to date and is the first report on the prospective diagnostic trial for beta-thalassemia in a Chinese population. In addition, we have performed 80 prenatal diagnoses based on screening for beta-thalassemia retrospectively.

Amino Acid Sequence↗
PubMed1996

Immunologic mechanisms in mosquito allergy: correlation of skin reactions with specific IgE and IgG antibodies and lymphocyte proliferation response to mosquito antigens.

BACKGROUND: Allergic reactions to mosquito bites are a common problem. Although IgE-mediated hypersensitivity has been reported, other immunologic mechanisms may be involved. OBJECTIVES: To study the relationship between skin bite reactions and immunologic parameters. METHODS: Forty-one subjects were experimentally exposed to mosquito (Aedes vexans) bites. Immediate and delayed skin reactions were traced at 20 minutes and 24 hours, respectively, after the bites. Sera were analyzed for mosquito salivary gland-specific IgE (mosquito-IgE) and IgG (mosquito-IgG) by ELISA. Lymphocyte proliferation assays with mosquito extract were also performed. RESULTS: One of 41 subjects had only a delayed skin reaction to the bite, 23 had both immediate and delayed reactions, 6 had only immediate reactions, and 11 had no reaction. The mean mosquito-IgE and -IgG concentrations were higher in the subjects with immediate reactions than in those without immediate reactions (P < .007). The mean lymphocyte proliferation stimulation index was higher in the subjects with delayed reactions than in those without delayed reactions (P < .015). Further, both mosquito-IgE and -IgG levels correlated with skin immediate and delayed reactions (P < .04), while lymphocyte proliferation indices only correlated with skin delayed reactions (P < .006). Inverse correlations were found between the size of skin reactions and the number of years lived in Canada (P < .04), but not with age. CONCLUSION: These results indicate that IgE-, lymphocyte- and, probably, local IgG immune-complex-mediated hypersensitivities are involved in mosquito allergy. Naturally acquired desensitization to mosquito bites occurs during long-term exposure.

Adult↗
PubMed1996

Comparison of proteins, IgE, and IgG binding antigens, and skin reactivity in commercial and laboratory-made mosquito extracts.

BACKGROUND: Commercial extracts are available for the diagnosis and treatment of mosquito allergy, but their antigen content has never been analyzed. OBJECTIVE: We wanted to analyze commercially available mosquito extracts and to compare these extracts with different laboratory preparations. METHODS: Seven commercially available mosquito whole body extracts from six companies and four laboratory mosquito preparations including saliva extract were studied. Epicutaneous tests and measurement of protein concentration were performed. Protein components were identified by sodium sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and silver stain. IgE and IgG binding antigens were analyzed by SDS-PAGE and immunoblotting with sera from mosquito-allergic subjects. RESULTS: The seven commercial materials produced wheals and papules ranging from 0 to 36 mm2. Their protein concentrations varied from 0.1 to 4.9 mg/mL. There were significant differences in their protein and antigen components. Some extracts contained multiple highly immunoreactive proteins and IgE- and IgG-binding antigens that are not present in mosquito saliva, but few actual salivary antigens. In the four laboratory preparations, rank ordered from whole body, head and thorax, salivary gland to saliva extracts, the amount of salivary antigens significantly increased, while non-salivary proteins and antigens significantly decreased. CONCLUSIONS: Commercial mosquito extracts should be standardized. Purer mosquito extracts should be used in diagnosis and immunotherapy of mosquito allergy.

Aedes↗
PubMed1996

Cross-reactivity and molecular mass of the epsilon chains of the IgE antibodies in dogs, humans, rats, and mice.

We report the cross-reactivities and comparative molecular masses of the IgE epsilon chains in humans, rats, mice, and dogs. Monoclonal human, rat, and mouse IgE, and our purified polyclonal dog IgE were used in the study. IgE of the 4 species, separated by SDS-PAGE, were analyzed by immunoblotting with polyclonal and monoclonal antihuman IgE, polyclonal and monoclonal antimouse IgE, monoclonal antirat IgE, and polyclonal antidog IgE antibodies. The polyclonal antihuman and polyclonal antimouse IgE cross-reacted with the IgE of the other 3 species, while their monoclonal forms cross-reacted with dog IgE only. Polyclonal antidog IgE cross-reacted with human and mouse IgE, while the monoclonal antirat IgE did not cross-react with any other species. "Reverse' passive cutaneous anaphylaxis in ragweed-sensitized dogs revealed that polyclonal antihuman and polyclonal antimouse IgE were able to elicit positive skin responses, and monoclonal antihuman, antirat, and antimouse IgE antibodies were not. The molecular masses of the epsilon chains were 77 kDa for mice, 75 kDa for rats and dogs, and 70 kDa for humans.

Animals↗
PubMed1996

Immunoblot analysis of IgE and IgG binding antigens in extracts of mosquitos Aedes vexans, Culex tarsalis and Culiseta inornata.

Extracts of one globally distributed mosquito species (Aedes vexans) and two North American species (Culex tarsalis and Culiseta inornata) were prepared from heads and thoraxes. Proteins of the three extracts were separated by 12% SDS-PAGE and transferred to nitrocellulose membranes for immunoblotting. Immunoblotting was completed by sequential incubations of the membranes with a pooled human serum from subjects allergic to mosquito bites, monoclonal antibodies to human IgE or IgG, and goat antimouse IgG conjugate. Twelve to sixteen antigens with molecular masses ranging from 18.5 to 160 kDa were found in each extract. Nine antigens were shared by 3 species and 6 were shared by 2 species. Only 3 were species-unique. Most antigens bound to both IgE and IgG antibodies. IgE and IgG antibodies against A. vexans were studied by immunoblotting using individual serum from subjects with or without skin reactions to A. vexans bites. All 3 subjects with severe skin reactions had strong IgE and IgG antibodies to 32.5, 40, and 50 kDa proteins. The patterns and magnitudes of IgE and IgG antibodies to the antigens varied among individuals. Very faint IgE antibodies to these antigens were found in the 2 subjects with no skin reactions, suggesting that IgE plays a role in the development of mosquito allergy.

Aedes↗
PubMed1996

Studies on the uptake mechanisms of 99mTc-labeled antibodies by liver tissue.

In this study, the roles of various protein alterations on the uptake of 99mTc labeled antibodies by isolated hepatocytes and by selected tissues in vivo were explored. In vitro binding studies of radiolabeled antibodies with hepatocytes demonstrated that the uptake of the radiolabel was a function of incubation duration and dose dependent. The uptake of 99mTc-antibodies could be inhibited by excess unlabeled F(ab')2 and Fc fragments as well as intact antibody. Liver uptake could not be reduced by a large insert pretreatment dose of unlabeled or aggregated antibody. These observations indicated that both Fab and Fc portions on the antibody molecule as well as the intact antibody may play important roles in the uptake of the radiolabel by liver tissue.

Animals↗
PubMed1996

Studies on metabolism of directly labeled 99mTc-antibody in mice.

The elucidation on the metabolic products of the 99mTc-antibody conjugates may provide insights and approaches that would reduce the undesirable deposition of radioactive species in normal tissues. In this investigation, the radiolabeled species in blood, urine, bile and extracts of liver and kidney obtained at different times after the injection of a model antibody, 99mTc-MAb170, into mice were analyzed with various chromatographic methods. Ninety-nine to 100% of the radioactivity in serum was associated with intact MAb170. The radioactivity in liver homogenate extract was strictly protein-bound to either intact MAb or low molecular weight species (LMW). In kidney extracts, the majority of the radioactivity was protein bound 99mTc, with less than 8% of the activity being non-protein bound 99mTc. Multiple 99mTc-containing protein and non-protein species were found in urine and bile. Evidence supporting the presence of 99mTc-cysteine and 99mTc-glutathione in bile, kidney and urine was also obtained. No evidence for the in vivo formation of 99mTc-pertechnetate in mouse blood, liver, kidney, bile and urine was observed.

Animals↗
PubMed1996

Approaches and reconstruction in skull base operation.

OBJECTIVE: To design convenient lateronasal and infrafrontal approaches or lateronasal subvolution approach to radically resect skull base tumors involving cranial cavity. METHODS: From 1987 through 1994, 22 patients with malignant tumors, 6 with benign tumors, one with a giant sphenoid sinus cyst and one with intranasal meningoencephalocele underwent the operation. Twenty-three cases had anterocranial fossa involved; 4, midcranial fossa; 2, anteromedial cranial fossa; and 1 case, posteromedial cranial fossa. Among the patients with malignant tumors, 11 underwent expansive maxillectomy and 10 had orbital contents resected. The intracranial approaches through lateronasal and infrafront (21 cases), nasal columella lateral subvolution (3 cases) and other approaches were used. RESULTS: The reconstruction of bony skull base defect in excess of 3.00 cm x 3.00 cm with total front musculocutaneous flap (8 cases), galeal and pericranial flap (5 cases) or other tissues (3 cases) has effectively prevented meningoencephalocele. Twelve cases had the dura resected in a range of 2.00 cm x 2.00 cm to 7.00 cm x 6.00 cm. Reconstruction of the dura defect with autofascia lata in 9 cases and other tissues in 3 cases effectively prevented the cerebrospinal fluid leak. Eight of 22 (36.4%) patients with malignant tumors have been alive and free of disease for 3-7 years after the operation. Six patients with benign tumors, one patient with giant sphenoid sinus cyst and one with meningoencephalocele were cured with this reconstructing method. CONCLUSIONS: Frontal musculocutaneous and pericranial flaps have advantages over free bone because of easy surviving and easy operating without occurrence of osteonecrosis and exclusive reaction.

Adolescent↗
PubMed1996

[The value of urine cystein proteinase and serum CA125 measurement in monitoring the treatment of malignant ovarian tumor].

Urine cystein proteinase (UCP) and serum CA125 were measured in 40 patients with malignant ovarian tumor (malignant group), 40 patients with benign ovarian tumor (benign group), and 40 normal control (normal group). 28 patients in the malignant group underwent UCP and CA125 measurement pre-operation, post-operation, and during three courses of chemotherapy. The enzyme activity of UCP in the malignant group was significantly higher than that in the benign and normal groups (P < 0.05 or 0.01). The values of UCP in patients with malignant tumor of stages II-IV were significantly higher compared with those of stages I-II (P < 0.01, 0.05). The activity of UCP was elevated pre-operation, post-operation, and was much higher on the seventh day postoperation. After the seventh day, UCP activity decreased gradually. Serum CA125 was also detected pre-operation, at 7.30 and 60 days post-operation. The levels of UCP and CA125 pre-operation and 30, 60 days post-operation in the patients whose residual carcinoma lesions were > 2 cm in diameter were apparantly higher than those with no residual lesions (P < 0.05). UCP and CA125 values were measured in six patients before relaparotomy. The sensitivity, specificity, accuaracy, positive predictive value and negative predictive value for UCP assay are 980%, 100%, 83%, 100% and 50% and those for CA125 assay are 40%, 100%, 80%, 100%, and 25%, respectively.

Biomarkers, Tumor↗
PubMed1996

[The value of CA125 and LDH assays in assisting diagnosis of epithelial ovarian carcinoma].

40 first-treated cases of epithelial ovarian cancer, 13 cases of cervical cancer, 13 cases of corpus cancer and 50 cases of benign tumor were included in this study from Jan. 1991 through May 1992 to evaluate the significance of the blood CA125, LDH, CR and SA levels in assisting diagnosis of epithelical ovarian cancer. The CA125 levels of the 40 canses of ovarian cancer were higher than those of cervical cancer and corpus cancer (P < 0.05); the SS, PLR and AC of CA125 in ovarian cancer were higher than those of LDH, SA and CR (P < 0.05); the SS of CA125 in ovarian cancer was higher than that of LDH isoenzyme (P < 0.05). The results show that CA125 may be the best tumor marker in assisting ovarian cancer; CA125 is more informative than LDH, CR and SA; when CA125 is used incombination with other tumor markers, SS, SP, NPV and PPV can be greatly raised.

Biomarkers, Tumor↗
PubMed1996

239 cases of high fever in viral upper respiratory infection (URI) treated with xiang shi qing jie (XSQJ) bag tea.

XSQJ bag tea was used to treat 239 cases of high fever caused by viral upper respiratory infection, widely spreading in summer and autumn. For comparison, a control group treated by penicillin combined with Ganmao Qingre Chongji or Banlangen Chongji was set up. The results showed the effect of XSQJ bag tea on the time of abating fever, resolving symptoms and physical signs were significantly better than that of the control group.

Adenovirus Infections, Human↗
PubMed1995

A rice HAL2-like gene encodes a Ca(2+)-sensitive 3'(2'),5'-diphosphonucleoside 3'(2')-phosphohydrolase and complements yeast met22 and Escherichia coli cysQ mutations.

A plant homolog of yeast HAL2 gene (RHL) was cloned from rice (Orizya sativa L.). The RHL cDNA complemented an Escherichia coli cysteine auxotrophic mutant, cysQ, and the yeast HAL2 mutant, met22. The latter is a methionine auxotroph and cannot use sulfate, sulfite, or sulfide as sulfur sources but exhibits wild-type activities of the enzymes necessary to assimilate sulfate and has normal sulfur uptake system. These results demonstrated that HAL2, cysQ, and RHL genes encode proteins with similar function in sulfur assimilatory pathway. The RHL cDNA expressed a 40-kDa protein that was shown to catalyze the conversion of adenosine 3'-phosphate 5'-phosphosulfate (PAPS) to adenosine 5'-phosphosulfate (APS) and 3'(2')-phosphoadenosine 5'-phosphate (PAP) to AMP. The enzyme activity is Mg(2+)-dependent, sensitive to Ca2+, Li+, and Na+ and activated by K+. The inhibition by Ca2+ depends on the Mg2+/Ca2+ ratio and is reversible by high Mg2+ concentration. The substrate specificity and kinetics of RHL enzyme are very similar to the Chlorella 3'(2'),5'-diphosphonucleoside 3'(2')-phosphohydrolase (DPNPase). Our evidence suggests that this enzyme regulates the flux of sulfur in the sulfur-activation pathway by converting PAPS to APS. Several residues that are essential for the activity of this enzyme were identified by site-directed mutagenesis, and the possible role of DPNPase in salt tolerance is discussed.

Adenosine Phosphosulfate↗
PubMed1995

Doppler echocardiographic characteristics of sinus of valsalva aneurysms.

This study evaluated the efficacy of a comprehensive transthoracic Doppler echocardiographic examination for correct detection of SVA and its associated lesions of VSD and aortic insufficiency. A consecutive series of 36 patients was obtained; all had surgical confirmation of the anatomic defects. The location of the SVA was correctly determined in 97% of patients, and the associated presence of a VSD was correctly determined in 79% of the studies. In the cases in which Doppler was available, all 11 patients with associated aortic insufficiency were detected. In this series 32 patients had right SVA, 3 had noncoronary sinus SVA, and 1 had a left SVA. Relative frequency of the rupture site location corresponded closely to that in previous necropsy studies. It is concluded that transthoracic Doppler echocardiography can correctly localize SVAs and most associated lesions.

Adult↗
PubMed1995

Identification of a dog IgD-like molecule by a monoclonal antibody.

IgD has not been identified in dogs. We produced a monoclonal antibody (mAb) designated 9B during the production of hybridomas to dog IgE. Using Western blot analysis under non-reducing conditions, the mAb (9B) recognized a predominant protein band of 185 kDa which was also recognized by anti-dog IgG F(ab')2, suggesting that this 185 kDa protein is an immunoglobulin (Ig) containing light chains. Under reducing conditions, the mAb (9B) recognized only one protein band of 55 kDa which presented a distinct molecular weight (MW) and immunoreactivity from the dog tau, mu, alpha, and epsilon chains. The 55 kDa band did not react with anti-dog IgE, IgM, IgA, and IgG, but did react with the mAb (9B). The MW was 75 kDa for the epsilon chain, 77.5 kDa for the mu chain, 58 kDa for the alpha chain, and 52 kDa for the tau chain. Further, by immunofluorescent staining, this Ig recognized by the mAb (9B) was found on the surface of dog lymphocytes. Studies of this dog Ig with the mAb revealed that this Ig bound to protein A and protein G-Sepharose, and that its enzyme-linked immunosorbent assay (ELISA) activity as measured by the mAb (9B) did not change after heating at 56 degrees C for 2 h. Ragweed-specific IgG, IgE, and this newly defined Ig significantly increased when dogs were immunized with ragweed extract. These data suggest that this Ig is a previously unrecognized IgD-like molecule in dogs.

Allergens↗