Biomedical subjects

X Ni

Publications and source records attributed to X Ni.

At least 19 recordsLinked to original sources

PubMed2006

p38 Mitogen-activated protein kinases is required for counteraction of 2-methoxyestradiol to estradiol-stimulated cell proliferation and induction of apoptosis in ovarian carcinoma cells via phosphorylation Bcl-2.

INTRODUCTION: 2-Methoxyestradiol (2ME2), a natural endogenous product of estradiol (E2) metabolism, has been shown to be a selective apoptotic agent for cancer cells but not for normal cells. In this study, we determined that 2ME2 counteracts E2-stimulated cell growth and induces apoptosis in ovarian carcinoma cells. In addition, we demonstrate that 2ME2 induces apoptosis via p38 and phospho-Bcl2 pathway. METHODS: 2ME2 and/or E2 were administered to the OVCAR-3 (human ovarian cancer) cell line. Cell growth inhibition was analyzed by [3H] Thymidine incorporation assay and DNA fluorometric assay. Cell apoptosis was tested by DNA fragmentation analysis and FACS. The signaling pathway was determined by a series of biochemical assays. RESULTS: 2ME2 inhibited estradiol-stimulated cell growth and induced apoptosis in an ovarian carcinoma cell line. MAPK and p38, but not JNK, were found to be critical mediators in this process. Expression of a dominant negative mutant of p38 kinase or p38 specific inhibitor, SB 203580, almost completely blocked the process. Furthermore, Bcl-2 phosphorylation was required for 2ME2-induced effects. CONCLUSION: Our data suggest that 2ME2 inhibits E2-stimulated proliferation and induces apoptosis in ovarian carcinoma cells. Furthermore, activation of p38 and phosphorylation of Bcl-2 plays a critical role in the mechanism. 2ME2 therefore, may have a clinical application for the treatment of ovarian cancer.

2-Methoxyestradiol↗

PubMed2006

Immunological advantage on small bowel graft induced by simultaneously transplanted liver in porcine auxiliary liver/small bowel transplantation.

BACKGROUND: We developed a new porcine model for auxiliary liver/small bowel transplantation (LSBT). The possible immunological advantage on small bowel graft induced by simultaneously transplanted liver in the large animal was assessed. METHODS: Thirty outbreed long-white pigs were randomized into two groups. Group A animals received LSBT without immunosuppressive treatment (n = 10). Group B animals had segmental small bowel allotransplantation without immunosuppressive treatment (n = 10). The postoperative survival time, initial acute rejection time, and pathological rejection scores were analyzed. RESULTS: There was no remarkable difference in survival time between groups A and B (10.33 days vs 12.89 days, P > .05), but the initial time of acute rejection in intestinal grafts in group A was obviously delayed when compared to group B (8.22 days vs 4.33 days, P < .05), and the rejection scores in group A were remarkably lower than those of group B (0 vs 0.44 on postoperative day (POD) 3, P < .05; 0.22 vs 1.78 on POD 5, P < .05; 1.11 vs 2.56 on POD 7, P < .05). CONCLUSIONS: An immunological advantage on intestinal graft can be induced by simultaneously transplanted liver in auxiliary LSBT. Compared to isolated segmental small bowel allotransplantation, the intestinal graft in LSBT has a delayed initial time of acute rejection and lower acute rejection scores. The liver graft may reduce the risk of intestinal rejection and thus protect the bowel graft.

Acute Disease↗

PubMed2006

The sorting and trafficking of lysosomal proteins.

For a long time lysosomes were considered terminal organelles involved in the degradation of different substrates. However, this view is rapidly changing by evidence demonstrating that these organelles and their content display specialized functions in addition to the degradation of substances. Many lysosomal proteins have been implicated in specialized cellular functions and disorders such as antigen processing, targeting of surfactant proteins, and most lysosomal storage disorders. To date, about fifty lysosomal hydrolases have been identified, and the majority of them are targeted to the lysosomes via the mannose-6-phosphate receptor (M6P-Rc). However, recent studies on the intracellular trafficking of the non-enzymic lysosomal proteins prosaposin and GM2 activator (GM2AP) demonstrated that they use an alternative receptor termed "sortilin". Existing evidence suggests that some hydrolases traffic to the lysosomes in a mannose 6-phophate-indepentend manner. The possibility that sortilin is implicated in the targeting of some soluble hydrolases, as well as the consequences of this process, is addressed in the present review.

Animals↗

PubMed2005

Modulation of water activity on fungicide effect on Aspergillus niger growth in Sabouraud dextrose agar medium*.

AIMS: To examine whether water activity (aw) in combination with low concentration of fungicides can be used to effectively control Aspergillus niger van Tieghem growth in cultural medium, the Sabouraud dextrose agar (SDA). The data would be used as baseline information for reducing A. niger contamination in insect artificial diets. METHODS AND RESULTS: Aspergillus niger was isolated from an insect artificial diet. Four concentration levels (i.e. 0, 1, 10 and 20 micromol) of two fungicides (i.e. amphotericin B and itraconazole) were tested against A. niger under four aw levels (i.e. 0.994, 0.961, 0.921 and 0.859) adjusted by including 0, 12.5, 25 and 38% of glycerol in the medium mixture. Aspergillus niger growth was significantly reduced at low fungicide concentration (1 micromol), and at reduced aw. The spore germination was prevented with either higher fungicide concentration (>10 micromol), or low aw in the medium (aw < 0.921). The two ecological determinants (fungicides and aw) showed a significant impact on A. niger survival in the medium (P < 0.0001). Itraconazole is more effective than amphotericin B in controlling A. niger contamination in the agar medium. CONCLUSION: Adjustment of aw (with 12.5% of glycerol) in combination with 1 mumol of itraconazole can effectively prevent A. niger growth in the SDA cultural medium. SIGNIFICANCE AND IMPACT OF THE STUDY: Aspergillus niger contaminations have frequently affected the quality of insects produced from mass rearing facilities. Low aw in combination with low fungicide concentration has the potential to become one of the most cost-effective management strategies to prevent A. niger contamination in insect artificial diets. The effect of fungicides and low aw in artificial diets on insect biology needs to be further examined.

Antifungal Agents↗

PubMed2004

Characterisation of human kallikrein 6/protease M expression in ovarian cancer.

Kallikrein 6 (hK6, also known as protease M/zyme/neurosin) is a member of the human kallikrein gene family. We have previously cloned the cDNA for this gene by differential display and shown the overexpression of the mRNA in breast and ovarian primary tumour tissues and cell lines. To thoroughly characterise the expression of this kallikrein in ovarian cancer, we have developed a novel monoclonal antibody specific to hK6 and employed it in immunohistochemistry with a wide range of ovarian tumour samples. The expression was found elevated in 67 of 80 cases of ovarian tumour samples and there was a significant difference in the expression levels between normal and benign ovarian tissues and the borderline and invasive tumours (P<0.001). There was no difference of expression level between different subtypes of tumours. More significantly, high level of kallikrein 6 expression was found in many early-stage and low-grade tumours, and elevated hK6 proteins were found in benign epithelia coexisting with borderline and invasive tissues, suggesting that overexpression of hK6 is an early phenomenon in the development of ovarian cancer. Quantitative real-time reverse transcription-polymerase chain reactions also showed elevated kallikrein 6 mRNA expression in ovarian tumours. Genomic Southern analysis of 19 ovarian tumour samples suggested that gene amplification is one mechanism for the overexpression of hK6 in ovarian cancer.

Antibodies, Monoclonal↗

PubMed2004

Progesterone receptors A and B differentially modulate corticotropin-releasing hormone gene expression through a cAMP regulatory element.

Corticotrophin-releasing hormone (CRH) plays a major role in mechanisms controlling human pregnancy and parturition. Gene regulation by progesterone may be a key point in the control of placental CRH production. Studies in primary placental cells show that antagonism of progesterone activity or production by RU486 or trilostane leads to an increase in CRH promoter activity. This effect can be reversed by the addition of progesterone. Overexpression of progesterone receptor A (PR-A) or glucocorticoid receptor resulted in a decrease in CRH promoter activity following progesterone treatment, whereas an increase in promoter activity was observed with overexpressed PR-B. Studies including mutation of the cAMP regulatory element (CRE) confirm this site to be essential for the progesterone-mediated effects. In summary, our results demonstrate that progesterone regulates CRH gene transcription via a CRE in the CRH promoter and that PR-A and PR-B exhibit different actions in the regulation of CRH gene expression.

5' Flanking Region↗

PubMed2003

Light activation of Russian wheat aphid-elicited physiological responses in susceptible wheat.

The impact of light and its role in Russian wheat aphid, Diuraphis noxia (Mordvilko), damage symptom formation, and photosynthetic capacity in 'Arapahoe' wheat (Triticum aestivum L.) were examined. After 72 h under continuous dark or continuous light regimes, the number of aphids (nymphs), leaf rolling and chlorosis ratings, fresh leaf weight, and chlorophyll contents were recorded. Photosynthetic rates, chlorophyll a, kinetics and chlorophyll extractions also were determined. Aphid infestation caused significant reductions in plant height, fresh weight, gas exchange, and chlorophyll fluorescence only under continuous light. Under the 72 h continuous dark regime, aphid infestation did not cause either damage symptom formation or reduction in plant growth or metabolism (photosynthesis). Furthermore, significantly more D. noxia nymphs were produced under continuous light condition than continuous dark. Our results demonstrate that the development of D. noxia feeding damage symptoms (i.e., leaf rolling and chlorotic streaks) on susceptible wheat seedlings is a light-activated process, even though the elicitor of the plant damage symptoms is aphid feeding.

Animals↗

PubMed2003

Comparison of chlorophyll and carotenoid concentrations among Russian wheat aphid (Homoptera: Aphididae)-infested wheat isolines.

Russian wheat aphid, Diuraphis noxia (Mordvilko), feeding injury on 'Betta' wheat isolines with the Dn1 and Dn2 genes was compared by assessing chlorophyll and carotenoid concentrations, and aphid fecundity. The resistant Betta isolines (i.e., Betta-Dn1 and Betta-Dn2) supported similar numbers of aphids, but had significantly fewer than the susceptible Betta wheat, indicating these lines are resistant to aphid feeding. Diuraphis noxia feeding resulted in different responses in total chlorophyll and carotenoid concentrations among the Betta wheat isolines. The infested Betta-Dn2 plants had higher levels of chlorophylls and carotenoids in comparison with uninfested plants. In contrast, infested Betta-Dn1 plants had the same level of chlorophyll and carotenoid in comparison with uninfested plants. Our data provide essential information on the effect of D. noxia feeding on chlorophyll and carotenoid concentrations for Betta wheat and its isolines with D. noxia-resistant Dn1 and Dn2 genes.

Animals↗

PubMed2002

Isolation and characterization of a human novel RAB (RAB39B) gene.

Rab proteins are small-molecular-weight GTPases that control vesicular trafficking in eukaryotic cells. During the large-scale sequencing analysis of a human fetal brain cDNA library, we isolated a cDNA clone encoding a novel Rab protein, which showed 74.2% identity with previously isolated Rab39A at the amino acid level. RAB39B was expressed in a variety of human tissues and located in human chromosome Xq28. It consisted of two exons spanning 3764 bp of human genomic DNA.

Adult↗

PubMed2002

Molecular cloning and characterization of a novel human gene (ANP32E alias LANPL) from human fetal brain.

Leucine-rich acidic nuclear protein (LANP) is a member of the leucine-rich repeats (LRRs) superfamily. Here we report on a human homologue of LANP, encoded by the gene ANP32E (alias LANPL). The gene was cloned and identified during large-scale sequencing analysis of a human fetal brain cDNA library. The human protein shared 70% amino acid identity with rat LANP. According to bioinformatics analysis, ANP32E is located on chromosome 1q22. RT-PCR analysis indicates that ANP32E was expressed in human peripheral blood leukocytes, colon, small intestine, prostate, thymus, spleen, skeletal muscle, liver and kidney.

Amino Acid Sequence↗

PubMed2001

Mössbauer study of atmospheric aerosols of Shanghai.

Three iron-containing atmospheric aerosol samples were collected, one at a tunnel, one near a viaduct, and one at a park in Shanghai City. These samples were studied by Mössbauer spectroscopy. The experimental results show that ultrafine particles alpha-Fe2O3 (about 13 nm) are the main component of the iron-containing atmospheric aerosols in the tunnel, and high-spin Fe3+ in sulfate containing a small amount of alpha-FeOOH is the main component of iron-containing particles in the aerosols from the other two places. The concentrations of iron in these locations, compared with those of some foreign cities, are much higher. To explore the chemical compositions of iron compounds in aerosols, SPM (scanning proton microprobe) has also been used. From these results, a possible chemical process by which the iron oxides converted to iron sulfate in air was discussed.

Aerosols↗

PubMed2001

Kinetics of enzymatic solid-to-solid peptide synthesis: synthesis of Z-aspartame and control of acid-base conditions by using inorganic salts.

Enzymatic peptide synthesis can be carried out efficiently in solid-to-solid reaction mixtures with 10% (w/w) water added to a mixture of substrates. The final reaction mass contains >/=80% (by weight) of product. This article deals with acid-base effects in such reaction mixtures and the consequences for the enzyme. In the Thermoase-catalyzed synthesis of Z-Asp-Phe-OMe, the reaction rate is strongly dependent on the amount of basic salts added to the system. The rate increases 20 times, as the KHCO(3) or K(2)CO(3) added is raised 2.25-fold from an amount equimolar to the Phe-OMe. HCL starting material. With further increases in KHCO(3) addition, the initial rate remains at the maximum, but with K(2)CO(3) it drops sharply. Addition of NaHCO(3) is less effective, but rates are faster if more water is used. With >1.5 equivalents of basic salt, the final yield of the reaction decreases. Similar effects are observed when thermolysin catalyzes the same reaction, or Z-Gln-Leu-NH(2) synthesis. These effects can be rationalized using a model estimating the pH of these systems, taking into account the possible formation of up to ten different solid phases.

Aspartame↗

PubMed2001

In vivo assembly of aspartate transcarbamoylase from fragmented and circularly permuted catalytic polypeptide chains.

Previous studies on Escherichia coli aspartate transcarbamoylase (ATCase) demonstrated that active, stable enzyme was formed in vivo from complementing polypeptides of the catalytic (c) chain encoded by gene fragments derived from the pyrBI operon. However, the enzyme lacked the allosteric properties characteristic of wild-type ATCase. In order to determine whether the loss of homotropic and heterotropic properties was attributable to the location of the interruption in the polypeptide chain rather than to the lack of continuity, we constructed a series of fragmented genes so that the breaks in the polypeptide chains would be dispersed in different domains and diverse regions of the structure. Also, analogous molecules containing circularly permuted c chains with altered termini were constructed for comparison with the ATCase molecules containing fragmented c chains. Studies were performed on four sets of ATCase molecules containing cleaved c chains at positions between residues 98 and 99, 121 and 122, 180 and 181, and 221 and 222; the corresponding circularly permuted chains had N termini at positions 99, 122, 181, and 222. All of the ATCase molecules containing fragmented or circularly permuted c chains exhibited the homotropic and heterotropic properties characteristic of the wild-type enzyme. Hill coefficients (n(H:)) and changes in them upon the addition of ATP and CTP were similar to those observed with wild-type ATCase. In addition, the conformational changes revealed by the decrease in sedimentation coefficient upon the addition of a bisubstrate analog were virtually identical to that for the wild-type enzyme. Differential scanning calorimetry showed that neither the breakage of the polypeptide chains nor the newly formed covalent bond between the termini in the wild-type enzyme had a significant impact on the thermal stability of the assembled dodecamers. The studies demonstrate that continuity of the polypeptide chain within structural domains is not essential for the assembly, activity, and allosteric properties of ATCase.

Allosteric Regulation↗

PubMed2001

Molecular cloning and characterization of a novel human gene (HSPBAP1) from human fetal brain.

Rat PASS1 is a novel protein binding specifically to hsp27 and thus plays a role in regulating stress response in the living cell. Here we report on a human homologue of PASS1, encoded by the gene HSPBAP1. The gene was cloned and identified during a large-scale sequencing analysis of a human fetal brain cDNA library. The human protein shared 80% amino acid identity with rat PASS1. According to bioinformatics analysis, the HSPBAP1 gene is located on chromosome 3q21. RT-PCR analysis indicated that HSPBAP1 was abundant in thymus and pancreas but had a ubiquitously low expression pattern in other human adult tissues except for brain where it was absent.

Amino Acid Sequence↗

PubMed2001

Oxidative responses of resistant and susceptible cereal leaves to symptomatic and nonsymptomatic cereal aphid (Hemiptera: Aphididae) feeding.

The impact of the leaf-chlorosis-eliciting Russian wheat aphid, Diuraphis noxia (Mordvilko), and the nonchlorosis-eliciting bird cherry-oat aphid, Rhopalosiphum padi (L.), feeding on D. noxia-susceptible and -resistant cereals was examined during the period (i.e., 3, 6, and 9 d after aphid infestation) that leaf chlorosis developed. After aphid number, leaf rolling and chlorosis ratings, and fresh leaf weight were recorded on each sampling date, total protein content, peroxidase, catalase, and polyphenol oxidase activities of each plant sample were determined spectrophotometrically. Although R. padi and D. noxia feeding caused significant increase of total protein content in comparison with the control cereal leaves, the difference in total protein content between R. padi and D. noxia-infested leaves was not significant. Although R. padi-feeding did not elicit any changes of peroxidase specific activity in any of the four cereals in comparison with the control leaves, D. noxia feeding elicited greater increases of peroxidase specific activity only on resistant 'Halt' wheat (Triticum aestivum L.) and susceptible 'Morex' barley (Hordeum vulgare L.), but not on susceptible 'Arapahoe' and resistant 'Border' oat (Avena sativa L.). D. noxia-feeding elicited a ninefold increase in peroxidase specific activity on Morex barley and a threefold on Halt wheat 9 d after the initial infestation in comparison with control leaves. Furthermore, D. noxia feeding did not elicit any differential changes of catalase and polyphenol oxidase activities in comparison with either R. padi feeding or control leaves. The findings suggest that D. noxia feeding probably results in oxidative stress in plants. Moderate increase of peroxidase activity (approximately threefold) in resistant Halt compared with susceptible Arapahoe wheat might have contributed to its resistance to D. noxia, whereas the ninefold peroxidase activity increase may have possibly contributed to barley's susceptibility. Different enzymatic responses in wheat, barley, and oat to D. noxia and R. padi feeding indicate the cereals have different mechanisms of aphid resistance.

Animals↗

PubMed2001

Fas ligand expression by neoplastic T lymphocytes mediates elimination of CD8+ cytotoxic T lymphocytes in mycosis fungoides: a potential mechanism of tumor immune escape?

Mycosis fungoides (MF) is the most common form of cutaneous T-cell lymphoma (CTCL) and arises from the accumulation and clonal proliferation of epidermotropic, CD4+/CD45RO+ (helper/memory) T lymphocytes. Loss of CD8+ CTLs within MF lesions is associated with poor prognosis and disease progression. Because T-lymphocyte apoptosis is controlled mainly through the Fas/Fas ligand (FasL) pathway and tumor cells may escape immune surveillance by expressing FasL, triggering apoptosis of tumor-infiltrating T lymphocytes, we studied the role of this system in MF. T-cell subsets, Fas/FasL expression, and apoptosis were evaluated in normal and lesional skin biopsy specimens from 21 patients with all stages of MF and in cultured CTCL cell lines (MJ, HUT78, and HH) using immunohistochemistry, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), and Western blotting. MF lesions and paired, clinically "normal," uninvolved skin showed increased numbers of both TUNEL-positive epidermal keratinocytes (n = 13; F = 31.146; P < 0.01, ANOVA) and dermal lymphocyte infiltrates (n = 13; F = 15.825, P < 0.01, ANOVA) compared with the normal control skin. FasL expression was highest in lesional epidermal keratinocytes, in CTCL tumor cell lines, and in dermal tumor lymphocytes in MF lesions compared with uninvolved skin. FasL colocalized with CD45RO+ cells. CD8+ cells in or adjacent to CD45RO+ cells were positively labeled by TUNEL for apoptosis. In addition, CD8+ cell numbers were decreased in areas in which FasL+ tumor cells were abundant (2.01 +/- 0.86%) compared with non-FasL expressing areas (13.53 +/- 3.54%; P < 0.02). These results suggest that a potential mechanism of tumor immune escape in MF is FasL-mediated apoptosis of infiltrating CD8+ CTLs.

Adult↗

PubMed2001

[A preliminary result of treatment of progressive multiple sclerosis with autologous peripheral blood stem cell transplantation in China].

OBJECTIVE: To explore the clinical effect for treatment of progressive multiple sclerosis (PMS) by autologous peripheral blood stem cell transplantation (Auto-PBSCT). METHODS: One PMS patient was chosen. Peripheral blood stem cells (PBSCs) were mobilized with cyclophosphamide and G-CSF. The CD34+ cells harvesting was performed by continuous flow leukapheresis using a CS3000 plus blood separator. About 12.2 x 10(6) CD34+ cells/kg was collected and preserved at -196 degrees C in liquid nitrogen. PBSCs were reinfused after conditioned by CTX (120 mg/kg) and TBI(10 GY). G-CSF was used to help hematopoietic and immunologic reconstitution. RESULTS: After transplantation the patient received clinical remission, and the abnormal signals of MRI in T1-T4 disappeared, the examination results of the neuro-electrophysiology and T cell subgroup were improved obviously. There was no relapse after 6 months follow up. CONCLUSIONS: Auto-PBSCT is effective and safety for PMS. Duration of remission remains to be decided in long-term follow up.

Adult↗

PubMed2001

[In vitro study of the anti-pneumocystis carinii effect of arteminsin derivatives].

OBJECTIVE: In vitro study was carried out to assess the effect of dihydroarteminsinin (DHA) and sodium artesunate (ATS) on pneumocystis carinii (Pc). METHODS: The drugs were added into HepG-2 cell cultures containing Pc cysts. The concentrations of dihydroarteminsinin (DHA) were 100, 50, 10, 5, 0.5 micromol/L respectively. The concentrations of sodium artesunate (ATS) were 100, 50, 10, 5 micromol/L respectively and pentamidine (PTD) was 15 micromol/L as a control. The supernatants were withdrawn every other day and evaluated for Pc trophozoite and cyst counts by GMS and DQ stain. RESULTS: The peak of Pc multiplication was observed on 5th day. The inhibition rates of Pc trophozoites by DHA 50 micromol/L, 100 micromol/L and ATS 100 micromol/L were quite similar to that of pentamidine (PTD) 15 micromol/L. CONCLUSION: DHA and ATS can inhibit the growth of Pc as same as PTD, and DHA was slightly better than ATS.

Animals↗