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Biomedical subjects

Q Gao

Publications and source records attributed to Q Gao.

At least 55 records · Page 3Linked to original sources
PubMed2001

An unmediated hydrogen peroxide biosensor based on hemoglobin incorporated in a montmorillonite membrane.

Hemoglobin was incorporated in a montmorillonite membrane. Electrochemical and spectroscopic studies revealed that the electron transfer reactivity and peroxidase activity of the protein were both enhanced. Nevertheless, its structure was still maintained native-like in the membrane. An unmediated hydrogen peroxide biosensor was accordingly prepared. The calibration plot of this H202 sensor was linear in the range of 1.0 x 10(-6)-6.0 x 10(-4) mol L(-1). The relative standard deviation was 3.1% for six successive determinations at a concentration of 1.0 x 10(-4) mol L(-1). The detection limit was 6.0 x 10(-7) mol L(-1). Possible interferences in real sample analyses are discussed.

Animals↗
PubMed2001

Microarray analysis of pathogens and their interaction with hosts.

Microarrays are a promising technique for elucidating and interpreting the mechanistic roles of genes in the pathogenesis of infectious disease. Microarrays have been used to analyse the genetic polymorphisms of specific loci associated with resistance to antimicrobial agents, to explore the distribution of genes among isolates from the same and similar species, to understand the evolutionary relationship between closely related species and to integrate the clinical and genomic data. This technique has also been used to study host-pathogen interactions, mainly by identifying genes from pathogens that may be involved in pathogenicity and by surveying the scope of the host response to infection. The RNA expression profile of pathogens has been used to identify regulatory mechanisms that ensure gene expression in the appropriate environment, to hypothesize functions of hundreds of uncharacterized genes and to identify virulence genes that promote colonization or tissue damage. This information also has the potential to identify targets for drug design. Furthermore, microarrays have been used to investigate the mechanism of drug action and to delineate and predict adverse effects of new drugs. In this paper, we review the use of spotted and high-density oligonucleotide arrays to study the genetic polymorphisms of pathogens, host-pathogen interactions and whole-genome expression profiles of pathogens, as well as their use for drug discovery.

Bacteria↗
PubMed2001

Human papillomavirus type 16 E6-induced degradation of E6TP1 correlates with its ability to immortalize human mammary epithelial cells.

Recent analyses have identified a number of binding partners for E6, including E6AP, ERC55, paxillin, hDlg, p300, interferon regulatory factor 3, hMCM7, Bak, and E6TP1. Notably, association with E6 targets p53, E6TP1, myc, hMCM7, and Bak for degradation. However, the relative importance of the various E6 targets in cellular transformation remains unclear. E6 alone can dominantly immortalize normal human mammary epithelial cells (MECs), permitting an assessment of the importance of various E6 targets in cellular transformation. Studies in this system indicate that E6-induced degradation of p53 and E6 binding to ERC55 or hDlg do not correlate with efficient immortalization. Here, we have examined the role of E6TP1, a Rap GTPase-activating protein, in E6-induced immortalization of MECs. We tested a large set of human papillomavirus type 16 E6 mutants for their ability to bind and target E6TP1 for degradation in vitro and in vivo. We observed a strict correlation between the ability of E6 protein to target E6TP1 for degradation and its ability to immortalize MECs. Recent studies have identified telomerase as a target of E6 protein. Previous analyses of E6 mutants have revealed this trait to closely correlate with MEC immortalization. We examined our entire panel of E6 mutants for rapid induction of telomerase activity and found in general a strong correlation with immortalizing ability. The tight correlation between E6TP1 degradation and MEC immortalization strongly supports a critical role of functional inactivation of E6TP1 in E6-induced cellular immortalization.

Breast↗
PubMed2001

Multiple genetic changes are required for efficient immortalization of different subtypes of normal human mammary epithelial cells.

Multiple Genetic Changes Are Required for Efficient Immortalization of Different Subtypes of Normal Human Mammary Epithelial Cells. Breast cancer is the second leading cause of cancer-related deaths of women in the U.S. About 180,000 new cases of breast cancer are diagnosed each year, a quarter of them fatal. Early detection is the key to the survival of these patients. However, there are no molecular markers to detect breast cancer at very early stages. A hurdle in understanding the early molecular changes in breast cancer has been the difficulty in establishing premalignant lesions and primary breast tumors as in vitro cell cultures. Normal epithelial cells grow for a finite life span and then senesce. Immortalization is defined by continuous growth of otherwise senescing cells and is believed to represent an early stage in tumor progression. To examine these early stages, we and others have developed in vitro models of mammary epithelial cell immortalization. These models have been extremely important in understanding the role of various tumor suppressor pathways that maintain the normal phenotypes of mammary epithelial cells. In this paper, we describe the establishment of these models and their relevance to understanding the molecular changes that occur in early breast cancer. These models have helped to identify molecular changes that occur in early breast cancers and appear to be well suited to identify novel markers for early diagnosis of breast cancer.

Breast↗
PubMed2001

Effect of solvents on bioconversion of penicillin G to deacetoxycephalosporin G.

The bioconversion of penicillin G, an inexpensive substrate, to the valuable intermediate for semisynthetic cephalosporin production, deacetoxycephalosporin G (DAOG), had been recently shown to be increased by eliminating agitation and adding decane. The present work examining other solvents shows that all alkanes tested are equivalent to decane in activity but that other solvents are either inhibitory or less active than alkanes. Optimum conditions of pH and temperature for the alkane system are not very different from the previously used aqueous system.

Alkanes↗
PubMed2001

[A preliminary study on the organic carbon weathering fluxes in Beijiang River drainage].

Riverine water samples were collected from Hekou hydrometric station of Beijiang River in five hydrological seasons. The samples were analyzed of their organic carbon and total suspended substance, which demonstrated that the concentrations of particulate organic carbon (POC) changed synchronically with the concentrations of total suspended substance (TSS) in riverine water. The correlation between the concentrations of TSS and dissolved organic carbon (DOC), however, is sometimes positive and sometimes negative, and the correlation is not so notable as that between TSS and POC. With the concentration of total suspended substances increasing, the quality partition of organic carbon in total suspended substance decreased in a logarithm tendency. The transportation of organic carbon, especially of DOC, mainly takes place in flood peak periods. The weathering flux of organic carbon in Beijiang River drainage basin is about 10.01 x 10(6) g.km-2.a-1, which is constituted by 6.54 x 10(6) g.km-2.a-1 of POC and 3.47 x 10(6) g.km-2.a-1 of DOC. This pattern of organic carbon weathering flux in Beijiang drainage basin is consistent with that of most of the monsoon drainage basins.

Carbon↗
PubMed2001

[A gene analysis of the low density lipoprotein receptor in Chinese with homozygous familial hyperchol-esterolemia].

OBJECTIVE: To investigate low density lipoprotein receptor(LDLR) gene mutations in Chinese with familial hyperchol-esterolemia(FH). METHODS: Genomic DNA was extracted from five unrelated children with clinical diagnosis of homozygous FH, together with their family members. Promoter and all of the 18 exons of LDLR gene were amplified by polymerase chain reaction (PCR) and were analyzed by single strand conformation polymorphism (SSCP). The PCR products of abnormal patterns shown by SSCP were sequenced directly. RESULTS: Two point mutations (A606T, C263R) were found in two families respectively. The two mutations were only found in China, and C263R is a novel mutation. CONCLUSION: The two mutations of LDLR gene are the cause of FH and there may be LDLR gene mutations only carried by FH patients in China.

Asian People↗
PubMed2001

Climate controls on dust storm occurrence in Maowusu Desert, Inner Mongolia, north China.

Dust storms occurring in arid and semi-arid regions play a main role in the evolution of landscapes. Climate is generally regarded to be important factors influencing the occurrence of dust storm, however, the way of climate controlling dust storms had been poorly understood. In this paper, we present the Ew Index model to describe the relationship between climate variables and dust storm frequency using the available meteorological data from three meteorological stations in Maowusu Desert. This index model explains 83.6%, 69.5% and 65.09% of the variance of dust storm frequency in three regions from the north to the south, respectively and this difference is probably caused by the difference of the human disturbance. The Ew Index model is an effective predictor of dust storm frequency and provides us a quite good understanding on the occurrence of dust storms in Maowusu Desert.

China↗
PubMed2001

Spatial distribution analysis on climatic variables in northeast China.

Information ecology is a new research area of modern ecology. Here describes the spatial distribution analysis methods of four sorts of climatic variables, i.e. temperature, precipitation, relative humidity and sunshine fraction in Northeast China. First, digital terrain models was built with large-scale maps and vector data. Then trend surface analysis and interpolation method were used to analyze the spatial distribution of these four kinds of climatic variables at three temporal scale: (1) monthly data; (2) mean monthly data of thirty years, and (3) mean annual data of thirty years. Ecological information system were used for graphics analysis on the spatial distribution of these climatic variables.

Algorithms↗
PubMed2001

[Human telomerase RNA (hTR) expression in lung cancer in the Gejiu and Xuanwei regions of Yunnan].

OBJECTIVE: To investigate the correlation between the expression of hTR in and the pathogenesis of lung cancer in Gejiu and Xuanwei regions of Yunnan province. METHODS: By use of in situ hybridization, the expression of hTR gene was observed in 81 cases of lung cancer tissues including 24 cases of Gejiu Tin miners (GTM), 36 cases of Xuanwei farmers (XF) and 21 cases of other regions. RESULTS: hTR was detected in 65.4% (53/81) of the lung cancer cases. The positive rate of hTR in GTM, XF and other regions was 66.7% (16/24), 58.3% (21/36) and 76.2% (16/21) respectively. Positive hTR expression was not found in normal bronchial and alveolar epithelia, but was found in highly proliferating type II alveolar epithelial cells adjacent to the carcinoma (12.3%, 10/81). No significant difference was observed with regard to the positive rate of hTR expression among three different regions. There was no statistically significant correlation between the expression of hTR, the patients' sex, age and the differentiation degree of the tumor, but the expression of hTR was correlated with histological type and lymph node metastasis (P < 0.05). CONCLUSION: The expression of hTR is a prevailing event in lung cancer and therefore can be used as an indicator of lung malignancy.

Adult↗
PubMed2001

[Clinical significance of CD44 expression in ovarian epithelial tumors].

OBJECTIVE: To study the clinical significance of the adhesion molecule CD44 expression in ovarian epithelial tumors and its relation to the clinical manifestation of ovarian cancer. METHODS: The expression of CD44 protein and mRNA was examined by immunohistochemistry, RT-PCR, nested PCR and densitometric scanning. The correlation between CD44 expression and clinicopathological features was analyzed. RESULTS: In comparison with benign ovarian tumors, CD44H protein expression was significantly higher in ovarian cancer in terms of positive rate as well as the level of expression. The levels of mRNA expression in ovarian cancer positively correlated with the grade and stage. The CD44H mRNA expression level in primary tumor correlated with that in the metastatic lesions. High levels of expression of CD44H mRNA predicted poor survival probability. The expression rate of CD44V3, CD44V4/5 and CD44V6 protein was 21.2%, 19.2% and 15.4% respectively in ovarian cancer as compared to 3.1%, 12.5% and 0 in benign tumors. There was significant difference between the two groups in CD44V6. CONCLUSION: Epithelial carcinoma of ovary expresses high level of CD44H. The amount of CD44H mRNA expression increased with progression of ovarian cancer. It can serve as a predictor of prognosis. It may play an important role in the peritoneal dissemination of ovarian cancer. Expression of CD44V6 is characteristic of malignant ovarian epithelial tumor.

Cell Adhesion Molecules↗
PubMed2001

[Application of sequential culture in assisted reproductive technique].

OBJECTIVE: To investigate the effects of sequential culture technique on the outcomes of in vitro fertilization-embryo transfer(IVF-ET). METHODS: Sequential culture media were used in 47 IVF-ET cycles, and conventional medium in 114 cycles. The fertilization rate, cleavage rate and speed, good embryo rate and pregnancy rate were compared between these 2 groups. RESULTS: There were significantly higher embryo cleavage and quality score rate, pregnancy rate (97.9%, 64.4%, 46.7%) in sequential media group as compared those in conventional medium group (89.7%, 40.2%, 28.2%). CONCLUSION: Sequential culture system is more suitable for the development of cultured human oocytes and embryos.

Blastomeres↗
PubMed2001

[p53 mutation in lung cancer in Gejiu and Xuanwei regions of Yunnan Province].

OBJECTIVE: To incidence rates of lung cancer among tin miners in Gejiu and among peasants in Xuanwei are higher than the average incidence rate in Yunnan Province, and the causes of the disease in these two regions have been preliminarily clarified. This study was directed to the molecular biological basis of its pathogenesis. METHODS: Twenty-six specimens of the lung cancers of Gejiu tin miners(GTM) and 15 ones of Xuanwei peasants (XP) were examined by single-strand conformation polymorphism analysis of polymerase chain reaction products. RESULTS: Using PCR primers for the most highly conserved region of the p53 including exons 5-8, we have identified p53 mutations in 13 lung cancer tumor DNA samples of GTM and in 4 ones of XP. Nucleotide sequencing of one of the exon 5 mutations of GTM indicated that there was a C to T transition, which resulted in substitution of Val for Ala at amino acid 135, and there was an AAC to TTC transertion in the exon 7 of XP, which resulted in substitution of Phe for Asn at amino acid 247. CONCLUSION: p53 mutation is a frequent incident in lung cancer of GTM and XP, and two new mutation sites were found in p53 gene, which have not been reported before now. There was no statistically significant correlation between the detection of p53 mutation and the patient's age, sex, mining history and histologic type of the cancer.

China↗
PubMed2001

[An experimental study on effects of pingyangmycin on vessels].

OBJECTIVE: The aim of this study was to investigate the mechanism of Pingyangmycin sclerotherapy for cavernous hemangiomas. METHODS: Totally 9 rabbits (one as the control) were selected to be injected with Pingyangmycin and sodium morrhuate into the auricularis posterior vein, and then these veins were examined histologically 2, 7, 14 and 21 days after injection respectively. RESULTS: After injection, Pingyangmycin nonspecifically made the endothelia and veins defective, and induced proliferation of endothelial cells and smooth muscle cells after 7 days. Further, the veins became sclerostenosis 21 days after injection. On the other hand, sodium morrhuate caused thrombosis quickly and the vascular cavity disappeared. Finally, the thrombus became fibrogenesis. The local skin could be observed swollen and necrosis. CONCLUSION: Pingyangmycin is a better sclerosant for the therapy of cavernous hemangioma.

Animals↗
PubMed2001

[An experimental study of effects of injection of pingyangmycin on activities of enzyme of endothelial cells].

OBJECTIVE: The objective of this study is to investigate the mechanism of acute trauma of endothelium after injection of Pingyangmycin. METHODS: A total of 42 adult Wistar rats were divided randomly into experimental groups (24), positive control groups (12) and normal control group (6), and the rats in the experimental or the positive control groups were injected with Pingyangmycin or sodium morrhuate into the mesenteric veins respectively, and then the enzyme activity of hepatic endothelial cells and hepatocytes was examined histochemically 0.5, 1, 2, 4, 8 and 24 hours after injection. RESULTS: After injection, the activity of 5'-nucleinase(5'-N) in hepatic endothelial cells and that of lactic dehydrogenase (LDH) and succinodehydrogenase (SDH) in hepatocytes decreased gradually, but that injected Pingyangmycin was less than that injected sodium morrhuate. CONCLUSION: The trauma caused by Pingyangmycin is less than that caused by sodium morrhuate, but the reaction of trauma caused by both is nonspecific.

5'-Nucleotidase↗
PubMed2001

[Analysis of the reason that patients with chronic sinusitis having a negative CT manifestation].

OBJECTIVE: To explore the reason why the CT manifestation of the patients with chronic nasosinusitis is negative. METHOD: To analyze the clinical and CT manifestation of the patients with chronic sinusitis having a negative CT manifestation. RESULT: Pathological changes were found in all 8 patients during the course of endoscopic sinus surgery, such as pus storing in the sinus cavity, mucous swelling polypoidly, small polyps formation and so on. CONCLUSION: The reasons that the patients with chronic sinusitis having a negative CT manifestation are, 1. CT scan can only give a static one-off image, 2. partial volume effect, 3. maybe result from the location of CT scan and the resolving power of tomograph, 4. maybe attribute to the pathological classify of chronic sinusitis.

Adolescent↗
PubMed2001

[DNA character of the cholesteatoma].

OBJECTIVE: To compare the DNA character with in cholesteatoma tissues with that in normal skin. METHOD: DNA content within 25 cholesteatoma tissues and 10 normal postauricular skin was measured with flow cytometry. RESULT: The content of cholesteatoma tissues and postauricular skin specimens are a normal euploid. The cell number during S phase of cholesteatoma (10.9 +/- 2.32)% was higher than that in normal skin(7.31 +/- 2.82)%. CONCLUSION: Although the cholesteatoma has a very high proliferating character, the result suggest it isn' t a malignant tumor.

Adolescent↗