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Biomedical subjects

X Xiang

Publications and source records attributed to X Xiang.

At least 19 recordsLinked to original sources
PubMed2005

Functional analysis of a novel male fertility CYP86MF gene in Chinese cabbage (Brassica campestris L. ssp. chinensis makino).

In our earlier work, a cytochrome P450 CYP86MF gene was isolated from floral bud of Chinese cabbage (Brassica campestris L. ssp. chinensis Makino, syn. B. rapa L.) by mRNA differential display PCR (DD-PCR) and rapid amplification of cDNA ends (RACE). To unravel the biological function of CYP86MF gene, the antisense fragment from the CYP86MF gene was transferred into Chinese cabbage pak-choi (B. campestris ssp. chinensis var. communis Tsen et Lee). Out of 22 plants transformed with the antisense gene constructed from the CYP86MF, 20 reached to flowering stage. Morphological investigations showed that the transgenic plants developed the normal floral organ. However, they remained self-infertile, even when artificial self-pollination was performed in the bud stage. Pollen germination test indicated that the pollen from the transgenic line TB-2 could not germinate normally. Further physiological, biochemical and cytological analyses showed that only significant difference was detectable in contents of the endogenous hormones, and a layer of unknown material adhered to the surface of microspore. The present studies thus provided valuable clues for understanding the biological function of the CYP86C subfamily genes. Furthermore, our studies also demonstrate a novel method for obtaining artificial male sterility line of Chinese cabbage.

Base Sequence↗
PubMed2001

Allurin, a 21-kDa sperm chemoattractant from Xenopus egg jelly, is related to mammalian sperm-binding proteins.

Previously, we demonstrated that a protein from Xenopus egg jelly exhibits sperm chemoattractant activity when assayed by either video microscopy or by sperm passage across a porous filter. Here we describe the isolation and purification of allurin, the protein responsible for this activity. Freshly oviposited jellied eggs were soaked in buffer, and the conditioned medium was loaded onto an anion exchange column and eluted with an NaCl gradient. The active fraction was purified further by RP-HPLC, the chemoattractant protein appearing as a single sharp peak. The amino acid sequence of the protein, determined by direct sequencing and cloning of cDNAs coding for the protein, consisted of 184 amino acids having a molecular mass of 21,073 Da. The protein shares homology with the mammalian cysteine-rich secretory protein (CRISP) family that includes testes-specific spermatocyte protein 1, a cell adhesion protein which links spermatocytes to Seritoli cells, and acidic epididymal glycoproteins that bind to sperm and have been implicated in sperm-egg fusion. Phylogenetic analysis suggests that allurin evolved from the ancestral protein that gave rise to the mammalian CRISP family. Addition of allurin to this family portends that the CRISP family represents a group of "sperm escort" proteins, which bind to sperm at various steps in their life history, facilitating passage from one functional stage to the next. Allurin stands out in this regard, representing both the first vertebrate sperm chemoattractant to be purified and sequenced and the first member of the CRISP family to be found in the female reproductive tract.

Amino Acid Sequence↗
PubMed2001

Phase III, multicenter, double-blind, randomized study of letrozole, an aromatase inhibitor, for advanced breast cancer versus megestrol acetate.

PURPOSE: To compare two doses of letrozole (0.5 mg and 2.5 mg every day) and megestrol acetate (40 mg qid) as endocrine therapy in postmenopausal women with advanced breast cancer previously treated with antiestrogens. PATIENTS AND METHODS: This double-blind, randomized, multicenter, multinational study enrolled 602 patients, all of whom were included in the primary analysis in the protocol. Patients had advanced or metastatic breast cancer with evidence of disease progression while receiving continuous adjuvant antiestrogen therapy, had experienced relapse within 12 months of stopping adjuvant antiestrogen therapy given for at least 6 months, or had experienced disease progression while receiving antiestrogen therapy for advanced disease. Tumors were required to be estrogen receptor- and/or progesterone receptor-positive or of unknown status. Confirmed objective response rate was the primary efficacy variable. Karnofsky Performance Status and European Organization for Research and Treatment of Cancer quality-of-life assessments were collected for 1 year. RESULTS: There were no statistically significant differences among the three treatment groups for overall objective tumor response. Patients treated with letrozole 0.5 mg had improvements in disease progression (P =.044) and a decreased risk of treatment failure (P =.018), compared with patients treated with megestrol acetate. Letrozole 0.5 mg showed a trend (P =.053) for survival benefit when compared with megestrol acetate. Megestrol acetate was more likely to produce weight gain, dyspnea, and vaginal bleeding, and the letrozole groups were more likely to experience headache, hair thinning, and diarrhea. CONCLUSION: Given a favorable tolerability profile, once-daily dosing, and evidence of clinically relevant benefit, letrozole is equivalent to megestrol acetate and should be considered for use as an alternative treatment of advanced breast cancer in postmenopausal women after treatment failure with antiestrogens.

Aged↗
PubMed2001

The Aspergillus cytoplasmic dynein heavy chain and NUDF localize to microtubule ends and affect microtubule dynamics.

Cytoplasmic dynein is a multisubunit, minus end-directed microtubule motor that uses dynactin as an accessory complex to perform various in vivo functions including vesicle transport, spindle assembly, and nuclear distribution [1]. We previously showed that in the filamentous fungus Aspergillus nidulans, a GFP-tagged cytoplasmic dynein heavy chain (NUDA) forms comet-like structures that exhibited microtubule-dependent movement toward and back from the hyphal tip [2]. Here we demonstrate that another protein in the NUDA pathway, NUDF, which is homologous to the human LIS1 protein involved in brain development [3, 4], also exhibits such dynamic behavior. Both NUDA and NUDF are located at the ends of microtubules, and this observation suggests that the observed dynamic behavior is due to their association with the dynamic microtubule ends. To address whether NUDA and NUDF play a role in regulating microtubule dynamics in vivo, we constructed a GFP-labeled alpha-tubulin strain and used it to compare microtubule dynamics in vivo in wild-type A. nidulans versus temperature-sensitive loss-of-function mutants of nudA and nudF. The mutants showed a lower frequency of microtubule catastrophe, a lower rate of shrinkage during catastrophe, and a lower frequency of rescue. The microtubules in the mutant cells also paused longer at the hyphal tip than wild-type microtubules. These results indicate that cytoplasmic dynein and the LIS1 homolog NUDF affect microtubule dynamics in vivo.

Aspergillus nidulans↗
PubMed2001

Microtubule integrity regulates Pak leading to Ras-independent activation of Raf-1. insights into mechanisms of Raf-1 activation.

Growth factors activate Raf-1 by engaging a complex program, which requires Ras binding, membrane recruitment, and phosphorylation of Raf-1. The present study employs the microtubule-depolymerizing drug nocodazole as an alternative approach to explore the mechanisms of Raf activation. Incubation of cells with nocodazole leads to activation of Pak1/2, kinases downstream of small GTPases Rac/Cdc42, which have been previously indicated to phosphorylate Raf-1 Ser(338). Nocodazole-induced stimulation of Raf-1 is augmented by co-expression of small GTPases Rac/Cdc42 and Pak1/2. Dominant negative mutants of these proteins block activation of Raf-1 by nocodazole, but not by epidermal growth factor (EGF). Thus, our studies define Rac/Cdc42/Pak as a module upstream of Raf-1 during its activation by microtubule disruption. Although it is Ras-independent, nocodazole-induced activation of Raf-1 appears to involve the amino-terminal regulatory region in which the integrity of the Ras binding domain is required. Surprisingly, the Raf zinc finger mutation (C165S/C168S) causes a robust activation of Raf-1 by nocodazole, whereas it diminishes Ras-dependent activation of Raf-1. We also show that mutation of residues Ser(338) to Ala or Tyr(340)-Tyr(341) to Phe-Phe immediately amino-terminal to the catalytic domain abrogates activation of both the wild type and zinc finger mutant Raf by both EGF/4beta-12-O-tetradecanoylphorbol-13-acetate and nocodazole. Finally, an in vitro kinase assay demonstrates that the zinc finger mutant serves as a better substrate of Pak1 than the wild type Raf-1. Collectively, our results indicate that 1) the zinc finger exerts an inhibitory effect on Raf-1 activation, probably by preventing phosphorylation of (338)SSYY(341); 2) such inhibition is first overcome by an unknown factor binding in place of Ras-GTP to the amino-terminal regulatory region in response to nocodazole; and 3) EGF and nocodazole utilize different kinases to phosphorylate Ser(338), an event crucial for Raf activation.

Amino Acid Substitution↗
PubMed2001

Comparison of different methods of total RNA extraction for viral detection in sputum.

Examination of sputum specimens can be used for monitoring airway inflammation by means of immunological and molecular techniques. RNA extraction is essential for measurement of cytokine gene expression and for detection of many viral pathogens in sputum. In this study, three RNA extraction methods used commonly (acid guanidinium thiocyanate-phenol-chloroform extraction, Trizol and RNeasy Mini kit) were compared on the sputum of 14 patients who had chronic obstructive pulmonary disease. The effect of dithiothreitol pre-treatment on sputum RNA extraction was also investigated. The yield and purity of total RNA were determined by spectrophotometry. Reverse transcription-polymerase chain reaction (RT-PCR) results of the house keeping gene (glyceraldehyde-3-phosphate dehydrogenase) and RNA sequences specific to common respiratory viruses were compared. The results showed that (1) total RNA extracted with Trizol had highest yield and purity among the three RNA extraction methods; (2) there was no significant difference among the three RNA extraction methods on the house keeping gene and viral detection by RT-PCR; (3) dithiothreitol pre-treatment did not improve either the purity of total RNA, or RT-PCR signal. Moreover, dithiothreitol treatment reduced significantly the yield of total RNA. The results of the study indicate that the Trizol method appears to be superior for total RNA extraction from sputum, and dithiothreitol pre-treatment does not increase the efficiency of RNA extraction and RNA detection in sputum specimens.

Dithiothreitol↗
PubMed2000

Dynamics of cytoplasmic dynein in living cells and the effect of a mutation in the dynactin complex actin-related protein Arp1.

Cytoplasmic dynein is a minus-end-directed microtubule motor that participates in multiple cellular activities such as organelle transport and mitotic spindle assembly [1]. To study the dynamic behavior of cytoplasmic dynein in the filamentous fungus Aspergillus nidulans, we replaced the gene for the cytoplasmic dynein heavy chain, nudA, with a gene encoding a green fluorescent protein (GFP)-tagged chimera, GFP-nudA. The GFP-NUDA fusion protein is fully functional in vivo: strains expressing only the GFP-tagged nudA grow as well as wild-type strains. Fluorescence microscopy showed GFP-NUDA to be in comet-like structures that moved in the hyphae toward the growing tip. Retrograde movement of some GFP-NUDA comets after they arrived at the tip was also observed. These dynamics of GFP-NUDA were not observed in cells treated with a microtubule-destabilizing drug, benomyl, suggesting they are microtubule-dependent. The rate of GFP-NUDA tip-ward movement is similar to the rate of cytoplasmic microtubule polymerization toward the hyphal tip, suggesting that GFP-NUDA is associated and moving with the polymerizing ends of microtubules. A mutation in actin-related protein Arp1 of the dynactin complex abolishes the presence of these dynamic GFP-NUDA structures near the hyphal tip, suggesting a targeting role of the dynactin complex.

Aspergillus nidulans↗
PubMed2000

Culturally appropriate nutrition education improves infant feeding and growth in rural Sichuan, China.

Chinese studies indicate that the growth of rural infants and children lags behind that of their urban counterparts after 4 mo of age and that the gap is widening. However, the rural areas are home to >85% of China's 300 million children. Clearly, culturally appropriate rural complementary feeding interventions are needed to close the growth and health gaps. After a 1990 survey of infants in rural Sichuan confirmed that poor infant feeding practices rather than inadequate household food resources were responsible for the growth faltering, a year-long community-based pilot nutrition education intervention (n congruent with 250 infants each in Education and Control groups) was undertaken in four townships. The goal was to improve infant growth by improving infant feeding practices. Features of the intervention included the training and mobilizing of village nutrition educators who made monthly growth monitoring and complementary feeding counseling visits to all pregnant women and families with infants born during the intervention in the study villages. After 1 y, the Education group mothers showed significantly higher nutrition knowledge and better reported infant feeding practices than their Control group counterparts. Also, the Education group infants were significantly heavier and longer, but only at 12 mo (weight-for-age -1.17 vs. -1.93; P = 0.004; height-for-age -1.32 vs. -1.96; P = 0.022), had higher breast-feeding rates overall (83% vs. 75%; P = 0.034) and lower anemia rates (22% vs. 32%; P = 0.008) than the Control group infants. We conclude that these methods have potential for adaptation and development to other rural areas in the county, province and nation.

Breast Feeding↗
PubMed2000

[Detection of viral aetiology in cerebral spinal fluid samples from 580 clinical cases].

OBJECTIVE: To investigate the viral aetiology in cerebral spinal fluid (Csf) from 580 cases of CNS infection or FUO in Yuedong district from 1990 to 1997. METHODS: Virus isolation was done with Hep-2 and BHK-21 cells. RESULTS: 21 virus types of 5 kinds of viruses were isolated from 113 samples (19.5%). Clinically diagnosed diseases included viral encephalitis 17.8% (43/242), intracranial infection 20.2% (47/233), paralytic diseases 24.3% (9/37), FUO 37.5% (9/24), convulsion 16.0% (4/25), Guillain-Barre syndrome 5.3% (1/19). Virus infection included 11 cases of Poliovirus (constitutional ratio 0.0973, including 1 Polio-I, 8 Polio-II, 2 Polio-III); 54 cases of Coxsackie virus (0.477 9, including 11 CoxA24, 10 CoxBl, 2 Cox134, 3 CoxB5); 15 cases of ECHO virus (0.1327, including 4 ECHO-24, 3 ECRO-7, 2 ECHO-12 and each one of ECHO-3, 11,14,15,27,32); 25 cases of Enterovirus (0.2213, including 14 EV-70, 11 EV-71); 8 cases of Adenovirus (0.070 8, including 3 Adv-2, 3 Adv-3 and 2 Adv7). Results of different age groups indicated there was significant difference (P < 0.05) in virus detection rate in two age groups. Virus positive rates in different years were 1990-1991 14.2% (15/106), 1992-1993 14.1%(23/163), 1994-1995 26.1% (36/138), 1996-1997 22.5% (39/173), that showed a significant difference (P <0.05). CONCLUSIONS: Virus infection rate of CNS diseases and FUO showed an a ascending trend, and the different virus types and kinds were isolated in different periods.

Adenoviridae↗
PubMed2000

[Cytomegalovirus infection and the changes of T-lymphocyte subsets in RAU patients].

OBJECTIVE: To study the quantitative changes of the T-lymphocyte subsets in RAU patients with different stages and to know the influences of cytomegalovirus(CMV) on cellular immunity in RAU patients. METHODS: CD4(helper/inducer) and CD8(suppressor/cytotoxic) cells in the peripheral blood were tested with monoclonally immunocytochemical technique (APAAP method) in 26 ulcerative stage patients and 10 inactive patients. RESULTS: The percentages of CD4 and CD8 cell were 36.19% and 29.38% respectively in ulcerative stage. The ratio of CD4/CD8 was 1.28 and it was inverted (< 1.0) in 26.92% of the patients. The percentages of CD4, CD8 cells was 39.90% and 34.21% in inactive stage respectively. The ratio of CD4/CD8 was 1.17. The number of CD4 and CD8 cells in ulcerative stage and CD4 cells in inactive stage was significantly lower than the normal values, P < 0.05. The number of CD8 cells in inactive stage was not significantly different compared with the normal value. However the numbers of CD3(total T cells), CD4 and CD8 cells increased to some extent in inactive stage. CD4 cells was significantly lower in 11 human cytomegalovirus (HCMV) DNA positive patients than that in 9 HCMV DNA negative patients (P < 0.05). CONCLUSIONS: A permanent disorder of cellular immunity was an important part of pathogenesis in RAU. CMV infection may be an important factor resulting in the disorder of cellular immunity because of the imbalance of T lymphocyte subsets.

Adolescent↗
PubMed2000

[Clinical study on interferon treatment of chronic idiopathic thrombocytopenic purpura].

The efficacy and mechanism of interferon alpha-2a (IFN alpha-2a) were assessed in the treatment of chronic idiopathic thrombocytopenic purpura (cITP). 20 patients with cITP (treatment group) were treated with IFN alpha-2a 3MIU i.m. once a week for 8 weeks; 28 patients with cITP (control group) were treated with prednisone 1 mg/(kg.d) for 4 weeks. Blood platelet counts (BPC), megakaryocyte number, immunnological parameters, percent and absolute counts of reticulated platelets (RPs) and megakaryocyte colony formation units were observed before and after therapy. The results showed that the efficacy of IFN alpha-2a was better than that of corticosteroid, P < 0.05. The RPs% decreased and the platelet-producing megakaryocyte percentage increased from 11.43% to 33.19% significantly after IFN alpha-2a therapy, but there were no significant changes in immunnological parameters. These indicate that IFN alpha-2a is effective in treating cITP, the mechanism may be based on promoting the megakaryocyte development and activating the production of platelets.

Adolescent↗
PubMed1999

Isolation of a new set of Aspergillus nidulans mutants defective in nuclear migration.

In the filamentous fungus Aspergillus nidulans, nuclear migration in the germ tube is mediated by cytoplasmic dynein. We have previously reported the characterization of four nud (nuclear distribution) genes, nudA, nudC, nudF and nudG, involved in this process. The nudA and nudG genes respectively encode for the heavy chain and the 8-kDa light chain of cytoplasmic dynein. In this work, we describe an improved method for the isolation of nud mutants that has led to the identification of at least ten additional nud loci. We have cloned one of the genes, nudK, and determined that it encodes the actin-related protein Arp1, which is a component of the dynactin complex. This provides the first evidence that dynactin is involved in nuclear migration in A. nidulans.

Actins↗
PubMed1999

Hyphal tip growth and nuclear migration.

Recent molecular and cytological studies have greatly advanced our understanding of hyphal tip growth and nuclear migration in filamentous fungi. Mutants involved in various aspects of hyphal tip growth have been isolated. Genes involved in nuclear migration continue to be identified, including putative regulators. The role of microtubules and microtubule motor proteins in hyphal tip growth has also been studied.

Cell Nucleus↗
PubMed1999

[Effects of nitroglycerin on nitric oxide and endothelin derived from bronchial epithelial cells and alveolar macrophages in asthma].

OBJECTIVE: To investigate the changes of nitric oxide(NO) and endothelin(ET) derived from alveolar macrophages(AM) and bronchial epithelial cells (BEC), and the influences of nitroglycerin (NTG) on ET and NO in asthma. METHODS: BEC and AM from 15 patients with asthma exacerbation and 7 healthy control subjects were isolated and cultured for 48 hours. NO and ET levels in supernatants and expressions of iNOS-mRNA and ET-mRNA from cultured BEC and AM were examined by copper coated cadmiunm reduction, radioimmunoassay and in situ hybridization. RESULTS: The NO level and the ET level in supernatants, and expressions of iNOS-mRNA and ET-mRNA from BEC and AM of the untreated group were higher than those of other groups (P < 0.05, respectively); The NO level from BEC and AM in supernatants of NTG pretreated group were elevated significantly and the ET level and the expression of iNOS-mRNA and ET-mRNA were lower than those of asthma untreated group (P < 0.05, respectively); The NO, ET levels and expressions of iNOS-mRNA, ET-mRNA derived from AM were higher than those derived from BEC in patients with asthma (P < 0.05, respectively); expression of iNOS-mRNA from BEC and AM were negatively correlated with the NO level in supernatants of cultured BEC and AM from the group pretreated by NTG in asthma (r = -0.60, r = -0.59; P < 0.01). While the expression of iNOS-mRNA and ET-mRNA by BEC and AM from other groups were positively correlated with the NO level and the ET level in supernatants of BEC and AM in asthma (all r > or = 0.902; P < 0.01, respectively). CONCLUSIONS: BEC and AM from patients with asthma exacerbation secreted a large quantity of NO and ET because of the increased expressions of iNOS-mRNA and ET-mRNA; AM was the main source of elevated NO and ET in airways of patients with asthma exacerbation. NTG directly enhanced the production of NO and significantly inhibited the expression of ET-mRNA, and therefore decreased the production of ET.

Adult↗
PubMed1999

[A role of nitric oxide and endothelin in bronchial hyperreactivity in patients with mild and middle asthma].

OBJECTIVES: To probe into a role of nitric oxide(NO) and endothelin(ET) in bronchial hyperreactivity(BHR) in patients with mild and middle asthma. METHODS: MchPC20 was used as an index to evaluate BHR in the asthmatic patients. Endothelin and NO level in bronchial alveolar lavage fluid(BALF) obtained from 15 patients with attacking asthma(Group I), 8 patients with stable asthma (Group II) and 7 healthy control subjects (Group III) were examined by radioimmunoassay and copper coated cadmium reduction method, respectively. RESULTS: 1. MchPC20 and FEV1% in Group III were slightly higher than those in Group I (P < 0.05), and lower than those in Group III (P < 0.05), respectively; 2. NO and ET levels in BALF from Group I were higher than those from Group II and Group III (P < 0.05), respectively; 3. ET/NO ratio in Group I was higher than that in Group III (P < 0.05) and lower than that in Group II (P > 0.05); 4. NO and ET level in BALF from Group I were positively and negatively correlated with MchPC20, respectively(r = 0.83, P < 0.01; r = 0.75, P < 0.01); the correlation of NO and ET level in BALF from Group I was negative (r = 0.70, P < 0.01); 5. NO and ET levels in BALF and ET/NO ratio from Group II were slightly higher than those from Group III (P < 0.05), respectively. CONCLUSION: NO may improve and ET exacerbate BHR in patients with mild and middle asthma. Bronchial hyperreactivity of the patients with stable asthma displays lightly abnormal, which may be due to mild abnormality of NO, ET levels and ET/NO ratio in BALF.

Adult↗
PubMed1999

p53 gene mutations in non-small cell lung cancer detected by polymerase chain reaction single-strand conformation polymorphism analysis.

Mutations of the p53 tumor suppressor gene are the most frequent genetic alterations detected in human lung cancer. To assess the pathogenic significance of p53 gene alterations in Chinese non-small cell lung cancer (NSCLC), 74 paired samples of primary lung cancer and normal lung tissue far away from the cancer were analyzed for mutations of the p53 gene (exons 5-8) using exon-specific PCR, single-strand conformation polymorphism (PCR-SSCP). p53 mutations were observed in 55.4% (41/74) of the samples. No linkages were detected between the incidence of p53 mutations and histological type, lymph node metastasis, age or sex. Significant association between p53 mutations and degree of differentiation in adenocarcinomas, not in squamous cell carcinomas, was observed. The frequency of p53 mutations in smokers (65.3%) was higher than in nonsmokers (33.3%) and reached statistical significance. We also found p53 mutations in 6/7 samples which had tissue invasion and distant metastasis. These results suggest that smoking could be an important factor in lung carcinogenesis, p53 mutation is a worse prognosis indicator in adenocarcinomas and related to high aggressive behavior of human lung cancer.

Adenocarcinoma↗
PubMed1998

Identification of a blue photoluminescent composite material from a combinatorial library

A quaternary combinatorial masking strategy was used in conjunction with photolithography to generate compositionally diverse thin-film phosphor libraries containing 1024 different compositions on substrates 2.5 centimeters square. A parallel imaging system and scanning spectrophotometer were used to identify and characterize compositions in the library with interesting luminescent behavior. Optimal compositions were identified with the use of gradient libraries, in which the stoichiometry of a material was varied continuously. This process led to the identification of an efficient blue photoluminescent composite material, Gd3Ga5O12/SiO2. Experimental evidence suggests that luminescence in this material may arise from interfacial effects between SiO2 and Gd3Ga5O12.

Journal Article↗