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Yan Zhang

Publications and source records attributed to Yan Zhang.

At least 55 records · Page 3Linked to original sources
PubMed2006

Structural shifts of mucosa-associated lactobacilli and Clostridium leptum subgroup in patients with ulcerative colitis.

To understand the role of mucosa-associated microbiota in the pathogenicity of ulcerative colitis (UC), paired biopsies were obtained during colonoscopy from the ulcerated and nonulcerated gut mucosa of 24 patients with UC. Denaturing gradient gel electrophoresis analysis was employed to profile the composition of the dominant bacteria (16S rRNA gene V3 region) and three important groups: lactobacilli, the Clostridium leptum subgroup, and Bacteroides spp. The Pearson coefficient was used to estimate similarities between the bacterial communities of the paired biopsies for each patient. The average similarity values of bacterial composition between the paired samples were 94.8 +/- 3.8% for dominant bacteria, 59.9 +/- 26.1% for lactobacilli, 79.2 +/- 22.6% for the Clostridium leptum subgroup, and 88.7 +/- 16.4% for Bacteroides spp. The data revealed that lactobacilli and the Clostridium leptum subgroup were significantly different between the ulcerated and the nonulcerated regions. It also was noted that for lactobacilli, the composition varied significantly between biopsy sites irrespective of the location of UC in the gut but that the composition of the Clostridium leptum subgroup showed significant differences between paired samples from UC in the rectum and not in the left colon. Localized dysbiosis of the mucosa-associated intestinal microflora, especially for lactobacilli and the Clostridium leptum subgroup, may be closely related to UC.

Bacteroides↗
PubMed2006

Delivery after transfer of frozen-thawed embryos from in vitro-matured oocytes in a woman at risk for ovarian hyperstimulation syndrome.

The present report describes the birth of a healthy infant after cryopreservation of embryos produced from in vitro-matured oocytes retrieved from a woman at risk of developing ovarian hyperstimulation syndrome (OHSS) during conventional in vitro fertilization (IVF) cycles. A conventional long protocol including gonadotropin-releasing hormone agonist (GnRHa) and gonadotropins induced a risk of OHSS. Oocyte retrieval was performed on day 11 of the cycle, and 27 immature oocytes were obtained. Following incubation for 24 h in maturation medium, 74.1% (20/27) of the oocytes were at the metaphase II stage. Fourteen oocytes (14/20, 70.0%) were fertilized after intracytoplasmic sperm injection (ICSI) with her husband's spermatozoa and cultured for 3 days. On day 4 following oocyte retrieval, three embryos at the 8-16 cell stage were transferred into the woman's uterus, and five spare embryos were frozen. Since the fresh embryo transfer failed to result in pregnancy, three post-thaw embryos were transferred into the woman three months later. Transfer of the frozen embryos resulted in pregnancy with delivery of a healthy infant girl.

Adult↗
PubMed2006

SPL8, a local regulator in a subset of gibberellin-mediated developmental processes in Arabidopsis.

Gibberellins (GAs) are important plant growth regulators, regulating many plant developmental processes, including seed germination, root and stem elongation, rosette expansion, floral induction and anther development. The diverse effects of GAs on plant development make it critical to maintain an appropriate endogenous GA level and a fine-tuned GA signalling. Some global regulators in GA signalling have been identified but little is known about genes specifically involved in local implementation of GA signalling. Here we report that the Arabidopsis thaliana SBP-box gene SQUAMOSA-PROMOTER-BINDING-PROTEIN-LIKE8 (SPL8) acts as a local regulator in a subset of GA-dependent developmental processes. Previous knowledge holds that SPL8 is involved in reproductive development as deduced from its loss-of-function phenotype (Unte et al. (2003) Plant Cell 15:1009-1019). We now determined that constitutive overexpression of SPL8 affects fertility due to non-dehiscent anthers, likely resulting from a constitutive GA response, suggesting a positive role of SPL8 in GA-mediated anther development. On the other hand, SPL8 gain- and loss-of-function mutants showed opposite responses to GA and its biosynthetic inhibitor paclobutrazol (PAC) with respect to seed germination and root elongation during the seedling stage. Genes involved in GA biosynthesis and signalling are transcriptionally affected by altered SPL8 expression. Our study uncovered a tissue-dependent regulatory role for SPL8 in the response to GA signalling in plant development.

Arabidopsis↗
PubMed2006

Selection of donor nuclei in somatic cell-mediated gene transfer using a co-transfection method.

In this study, we introduced a co-transfection method for the selection of donor nuclei in somatic cell-mediated nuclear transfer. Two vectors were constructed in our experiment. One was pMSCV-GFP carrying the neomycin-resistant gene (Neo(r)) and the green fluorescent protein (GFP) reporter gene; the other was pBC1-GFP carrying the mammary gland-specific promoter and target gene GFP. Ovine adult fibroblasts were co-transfected with pMSCV-GFP and pBC1-GFP. The data from this work demonstrated that the GFP genes in both vectors could successfully co-integrate into the genomes of ovine adult fibroblasts in three of the four transgenic cell clones assayed. Furthermore, PCR analysis of transgenic embryos proved that the GFP genes in both vectors could co-integrate into the genomes of the reconstructed embryos. Subsequently, analysis of the developmental rate of the reconstructed embryos after nuclear transfer indicated that the blastocyst rate from the co-transfected donor cells was similar (approximate 8 percent) to that from individual pMSCV-GFP transfected donor cells. The influence of co-transfection resulting in modification of donor nuclei on development of reconstructed embryos was also investigated. The results of flow cytometric analysis indicated that the co-transfected ovine fibroblasts had similar quiescent characteristics in terms of cell cycle (G0+G1 percent: 73.20 +/- 4.04) to the individual pMSCV-GFP transfected fibroblasts (G0+G1 percent: 70.77 +/- 1.19) after they were treated with serum starvation for five days. Our results suggest that the co-transfection method can be used for selection of donor cell clones in somatic cell-mediated gene transfer experiments. It can be potentially extended to applications related to expression of functional protein in mammary glands and other transgenic research relevant to nuclear transfer.

Animals↗
PubMed2006

Ovariectomy worsens secondary hyperparathyroidism in mature rats during low-Ca diet.

Estrogen deficiency impairs intestinal Ca absorption and induces bone loss, but its effects on the vitamin D-endocrine system are unclear. In the present study, calciotropic hormones levels, renal vitamin D metabolism, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]-dependent intestinal calcium absorption, and bone properties in 3-mo-old sham-operated (sham) or ovariectomized (OVX) rats fed either a normal-Ca (NCD; 0.6% Ca, 0.65% P) or a low-Ca (LCD; 0.1% Ca, 0.65% P) diet for 2 wk were determined. LCD increased serum 1,25(OH)2D3 levels in both sham and OVX rats. Serum parathyroid hormone [PTH(1-84)] levels were highest in OVX rats fed LCD. Renal 25-hydroxyvitamin D1alpha-hydroxylase (1-OHase) protein expression was induced in both sham and OVX rats during LCD, while renal 1-OHase mRNA expression was highest in OVX rats fed LCD. Renal vitamin D receptor (VDR) and mRNA expressions in rats were induced by ovariectomy in rats fed NCD but suppressed by ovariectomy in rats fed LCD. The induction of intestinal calcium transporter-1 and calbindin-D9k mRNA expressions by LCD were not altered by ovariectomy. As expected, bone Ca content, cancellous bone mineral density, and bone strength index in proximal metaphysis of rat tibia were reduced by both ovariectomy and LCD (P<0.05) as analyzed by two-way ANOVA. Taken together, the data demonstrate that ovariectomy alters the responses of circulating PTH levels, renal 1-OHase mRNA expression, and renal VDR expression to LCD. These results suggest that estrogen is necessary for the full adaptive response to LCD mediated by both PTH and 1,25(OH)2D3.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2006

A study on antigenicity and receptor-binding ability of fragment 450-650 of the spike protein of SARS coronavirus.

The spike (S) protein of SARS coronavirus (SARS-CoV) is responsible for viral binding with ACE2 molecules. Its receptor-binding motif (S-RBM) is located between residues 424 and 494, which folds into 2 anti-parallel beta-sheets, beta5 and beta6. We have previously demonstrated that fragment 450-650 of the S protein (S450-650) is predominantly recognized by convalescent sera of SARS patients. The N-terminal 60 residues (450-510) of the S450-650 fragment covers the entire beta6 strand of S-RBM. In the present study, we demonstrate that patient sera predominantly recognized 2 linear epitopes outside the beta6 fragment, while the mouse antisera, induced by immunization of BALB/c mice with recombinant S450-650, mainly recognized the beta6 strand-containing region. Unlike patient sera, however, the mouse antisera were unable to inhibit the infectivity of S protein-expressing (SARS-CoV-S) pseudovirus. Fusion protein between green fluorescence protein (GFP) and S450-650 (S450-650-GFP) was able to stain Vero E6 cells and deletion of the beta6 fragment rendered the fusion product (S511-650-GFP) unable to do so. Similarly, recombinant S450-650, but not S511-650, was able to block the infection of Vero E6 cells by the SARS-CoV-S pseudovirus. Co-precipitation experiments confirmed that S450-650 was able to specifically bind with ACE2 molecules in lysate of Vero E6 cells. However, the ability of S450-510, either alone or in fusion with GFP, to bind with ACE2 was significantly poorer compared with S450-650. Our data suggest a possibility that, although the beta6 strand alone is able to bind with ACE2 with relatively high affinity, residues outside the S-RBM could also assist the receptor binding of SARS-CoV-S protein.

Angiotensin-Converting Enzyme 2↗
PubMed2006

Dynamic evolution of selenocysteine utilization in bacteria: a balance between selenoprotein loss and evolution of selenocysteine from redox active cysteine residues.

BACKGROUND: Selenocysteine (Sec) is co-translationally inserted into protein in response to UGA codons. It occurs in oxidoreductase active sites and often is catalytically superior to cysteine (Cys). However, Sec is used very selectively in proteins and organisms. The wide distribution of Sec and its restricted use have not been explained. RESULTS: We conducted comparative genomics and phylogenetic analyses to examine dynamics of Sec decoding in bacteria at both selenium utilization trait and selenoproteome levels. These searches revealed that 21.5% of sequenced bacteria utilize Sec, their selenoproteomes have 1 to 31 selenoproteins, and selenoprotein-rich organisms are mostly Deltaproteobacteria or Firmicutes/Clostridia. Evolutionary histories of selenoproteins suggest that Cys-to-Sec replacement is a general trend for most selenoproteins. In contrast, only a small number of Sec-to-Cys replacements were detected, and these were mostly restricted to formate dehydrogenase and selenophosphate synthetase families. In addition, specific selenoprotein gene losses were observed in many sister genomes. Thus, the Sec/Cys replacements were mostly unidirectional, and increased utilization of Sec by existing protein families was counterbalanced by loss of selenoprotein genes or entire selenoproteomes. Lateral transfers of the Sec trait were an additional factor, and we describe the first example of selenoprotein gene transfer between archaea and bacteria. Finally, oxygen requirement and optimal growth temperature were identified as environmental factors that correlate with changes in Sec utilization. CONCLUSION: Our data reveal a dynamic balance between selenoprotein origin and loss, and may account for the discrepancy between catalytic advantages provided by Sec and the observed low number of selenoprotein families and Sec-utilizing organisms.

Bacteria↗
PubMed2006

Enriched environment treatment restores impaired hippocampal synaptic plasticity and cognitive deficits induced by prenatal chronic stress.

Prenatal stress can cause long-term effects on cognitive functions in offspring. Hippocampal synaptic plasticity, believed to be the mechanism underlying certain types of learning and memory, and known to be sensitive to behavioral stress, can be changed by prenatal stress. Whether enriched environment treatment (EE) in early postnatal periods can cause a recovery from these deficits is unknown. Experimental animals were Wistar rats. Prenatal stress was evoked by 10 foot shocks (0.8 mA for 1s, 2-3 min apart) in 30 min per day at gestational day 13-19. After weaning at postnatal day 22, experimental offspring were given the enriched environment treatment through all experiments until tested (older than 52 days age). Electrophysiological and Morris water maze testing was performed at 8 weeks of age. The results showed that prenatal stress impaired long-term potentiation (LTP) but facilitated long-term depression (LTD) in the hippocampal CA1 region in the slices. Furthermore, prenatal stress exacerbated the effects of acute stress on hippocampal LTP and LTD, and also impaired spatial learning and memory in the Morris water maze. However, all these deficits induced by prenatal stress were recovered by enriched environment treatment. This work observes a phenomenon that may contribute to the understanding of clinically important interactions among cognitive deficit, prenatal stress and enriched environment treatment. Enriched environment treatment on early postnatal periods may be one potentially important target for therapeutic interventions in preventing the prenatal stress-induced cognitive disorders.

Animals↗
PubMed2006

Nonadiabatic effects in the H+D2 reaction.

The state-to-state dynamics of the H+D2 reaction is studied by the reactant-product decoupling method using the double many-body expansion potential energy surface. Two approaches are compared: one uses only the lowest adiabatic sheet while the other employs both coupled diabatic sheets. Rotational distributions for the reaction H+D2 (upsilon = 0, j = 0)-->HD(upsilon' = 3, j')+D are obtained at eight different collision energies between 1.49 and 1.85 eV; no significant difference are found between the two approaches. Initial state-selected total reaction probabilities and integral cross sections are also given for energies ranging from 0.25 up to 2.0 eV with extremely small differences being observed between the two sets of results, thus showing that the nonadiabatic effects in the title reaction are negligible at least for small energies below 2.0 eV.

Journal Article↗
PubMed2006

Validation of the wall motion score and myocardial performance indexes as novel techniques to assess cardiac function in mice after myocardial infarction.

The aim of this study was to determine the feasibility and accuracy of wall motion score index (WMSI) and myocardial performance index (MPI) for measuring regional and global left ventricular (LV) function with use of high-resolution echocardiography after myocardial infarction (MI) in mice. In 48 mice, myocardial infarction was induced by ligation in the middle of the left anterior descending coronary artery. Echocardiography was performed under anesthesia at baseline and 1 mo after MI. WMSI was analyzed by a 16-segment model on short-axis views, and wall motion was scored as 1 for normal, 2 for hypokinetic, 3 for akinetic, 4 for dyskinetic, and 5 for aneurysmal. WMSI was calculated as the sum of scores divided by the total number of segments. MPI was calculated on the basis of isovolumetric contraction time (IVCT), isovolumetric relaxation time (IVRT), and ejection time (ET): MPI = (IVCT + IVRT)/ET. We measured LV ejection fraction (LVEF), end-systolic and end-diastolic volumes (ESV and EDV), fractional shortening (FS), and infarct size (IS). LVEF at 4 wk after MI was reduced at 32.8 +/- 9.0%. Linear correlation analyses showed that WMSI (1.6 +/- 0.3) correlated with LVEF (r = -0.84, P < 0.0005), FS (r = -0.43, P = 0.003), and IS (34.3 +/- 15.3%, r = 0.86, P < 0.0005). MPI (0.67 +/- 0.09) correlated with LVEF (r = -0.67, P < 0.0005) and IS (r = 0.72, P < 0.0005). MPI also correlated with mitral inflow velocity (r = -0.68, P < 0.0005) and deceleration time (r = -0.42, P = 0.003). Stepwise regression analysis revealed that WMSI was independently associated with IS. IS, FS, mitral inflow velocity, and deceleration time were independent determinants of MPI. In conclusion, echocardiographic assessments of WMSI and MPI in mice are feasible and correlate strongly with two-dimensional measurement of LV function and IS. These novel parameters provide additional noninvasive assessment of regional and global LV function in mice after MI.

Animals↗
PubMed2006

Development and analytical application of an uric acid biosensor using an uricase-immobilized eggshell membrane.

An uric acid biosensor fabricated from a uricase-immobilized eggshell membrane and an oxygen electrode was presented. The detection schemes involve the enzymatic reactions of the uricase leading to the depletion of dissolved oxygen level upon exposure to uric acid solution. The decrease in oxygen level was monitored and related to the uric acid concentration. The scanning electron micrographs show the microstructure of the eggshell membrane within which the uricase is successfully immobilized. The effects of enzyme loading, pH, temperature, and phosphate buffer concentration on the response of the biosensor were investigated in detail. The uric acid biosensor has a linear response range of 4.0-640 microM with a detection limit of 2.0 microM (S/N=3). The response time was less than 100 s. The biosensor exhibited good repeatable response to a 0.10mM uric acid solution with a relative standard deviation of 3.1% (n=7). The reproducibility of fabrication of the biosensors using four different membranes was good with a R.S.D. of 3.2%. The biosensor showed extremely good stability with a shelf-life of at least 3 months. Some common potential interferents in samples such as glucose, urea, ascorbic acid, lactic acid, glycine, DL-alpha-alanine, DL-cysteine, KCl, NaCl, CaCl2, MgSO4, and NH4Cl showed no interferences on the response of the uric acid biosensor. The biosensor was successfully applied to determine the uric acid level in some human serum and urine samples, and the results agreed well with those obtained by a commercial colorimetric assay kit.

Animals↗
PubMed2006

Toxicity and quality of life after cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy.

BACKGROUND: The purpose of our study was to determine the toxicity and quality of life for patients with peritoneal metastases after cytoreductive surgery (CS) plus hyperthermic intraperitoneal chemotherapy (HIPC). METHODS: From 2001 to 2005, 35 consecutive patients with peritoneal metastases enrolled in a prospective trial approved by the University of Minnesota Institutional Review Board. Their primary cancer sites included the appendix (19 patients), colon (7), mesothelioma (3), stomach (2), small bowel (2), gallbladder (1), and unknown (1). We performed CS in an effort to remove all or nearly all peritoneal tumor nodules. Using a closed technique, we administered hyperthermic mitomycin C into the peritoneal cavity for 90 min. Before treatment and then at 4-month postoperative intervals, we used the functional assessment of cancer therapy-colon subscale (FACT-C) instrument to assess the patients' quality of life. RESULTS: The median hospital stay was 9 days; 12 patients were hospitalized at least 30 days or required readmission within 30 days after treatment. The postoperative mortality rate was 0%; adverse events occurred in 18 (51%) patients. As of December 2005, 20 patients were alive; 14 had died of progressive disease and 1 of an unrelated cause. The median survival time was 21.4 months. Quality of life measurements, including trial outcome index (TOI), FACT-colon, and FACT-general, returned to baseline 4 months after treatment and were significantly improved at 8 and 12 months. CONCLUSIONS: Despite early toxicity, CS plus HIPC may prolong the overall survival rate of patients with peritoneal metastases and improve quality of life measurements.

Antibiotics, Antineoplastic↗
PubMed2006

Efficient and direct synthesis of poly-substituted indeno[1,2-b]quinolines assisted by p-toluene sulfonic acid using high-temperature water and microwave heating via one-pot, three-component reaction.

Reactions of aldehydes, 1,3-indanedione and enaminones were successfully carried out using p-toluene sulfonic acid (p-TsOH) as a catalyst and high-temperature water as a solvent under microwave irradiation. This method provided several advantages such as rapid reaction times, high yields, and a simple workup procedure. In addition, a possible mechanism to account for the reaction was proposed.

Catalysis↗
PubMed2006

Adrenomedullin in adipocyte differentiation of human mesenchymal stem cells.

Expression of adrenomedullin (AM), a potent vasodilator peptide, was studied during adipocyte differentiation of human mesenchymal stem cells (hMSCs). Immunoreactive AM levels in the medium were increased at day 4 and 8 of the adipocyte differentiation. Northern blot analysis showed increased expression of AM mRNA in hMSCs-derived adipocytes at day 4, 8, 12, and 18. Transient transfection assay showed that the promoter activity was higher in hMSCs-derived adipocytes than in hMSCs, when cells were transfected with plasmids containing a cis-acting region (-70/-29) of the human AM gene. Electrophoretic mobility shift assay showed that specific bands bound to the region (-70/-29) in hMSCs-derived adipocytes but not in hMSCs, and were abolished by the stimulatory protein 1 (Sp1) antibody. The present study has shown that AM expression is up-regulated during adipocyte differentiation of hMSCs probably via the interaction between Sp1 or Sp1-related factor(s) and the AM promoter region (-70/-29).

Adipocytes↗
PubMed2006

Fluorescence determination of metoprolol in human plasma by trilinear decomposition-based calibration techniques.

In this study a new spectrofluorimetric method for the direct determination of metoprolol in human plasma is presented and discussed. It is based on the use of fluorescence excitation-emission matrices (EEMs) and second-order calibration performed with parallel factor analysis (PARAFAC) or alternating trilinear decomposition (ATLD). This methodology enables accurate and reliable discrimination of the analyte signal, even in the presence of unknown and uncalibrated fluorescent component(s), which is often referred to as the second-order advantage. No separation or sample pretreatment steps were required. Satisfactory results were obtained. Metoprolol recoveries in plasma were determined as 87+/-2% and 90+/-4% with PARAFAC and ATLD, respectively. All RSD values of intra- and interday assays were below 5%.

Calibration↗
PubMed2006

In vitro propagation of spermatogonial stem cells from KM mice.

Spermatogonial stem cells (SSCs) are a unique type of stem cells in that they transmit genetic information to the next generation by producing sperms. Studies of SSC proliferation and differentiation have been hampered by the inability of reconstructing these processes in vitro, particularly in a serum-free culture system. Several groups have reported the long term culture of SSCs during which SSCs self-renew and restore spermatogenesis when transplanted back to recipient testes. However, different protocols and mice with particular genetic background have been used by different laboratories, and the techniques have not been adopted widely. In the present study, we first established a SSC isolation and culture system composed of differential adherence selection of SSCs, serum-free medium and mouse embryonic fibroblast (MEF) feeder cells. SSCs from KM pups could be cultured on MEF feeders in StemPro-34 SFM Medium supplemented with glial cell line-derived neurotrophic factor (GDNF), soluble GDNF family receptor alpha-1 (GFRa1) and basic fibroblast growth factor (bFGF) for 1 month. These SSCs were characterized morphologically and by examining the expression of marker genes. Expression of Oct4 and Sox2, which are crucial factors in embryonic stem cell (ESC) self-renewal, were detected in our cultured SSCs, suggesting that SSCs may share with ESCs some common mechanisms in self-renewal regulation. We also found that LIF had no effect on the proliferation of cultured SSCs derived from KM mice.

Animals↗