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Z Xu

Publications and source records attributed to Z Xu.

At least 37 records · Page 2Linked to original sources
PubMed2005

Chemical ablation of the gallbladder: clinical application and long-term observations.

BACKGROUND: We investigated whether minicholecystostomy followed by chemical ablation of the gallbladder could be used as a alternative to cholecystectomy in patients at high risk for complications of surgery. METHODS: From January 1990 through January 2003, 34 patients at high risk underwent minicholecystostomy. Six weeks after the operation, microwave irradiation was provided to burn the mucosa of the cystic duct at locations at 3, 6, 9, and 12 o'clock around the orifice. Each location was treated eight times at 50 mA for 10 sec. Then chemical ablation of the gallbladder was performed by infusing 95% ethanol into the gallbladder cavity for 30 min. For each sclerosis course, the procedure was repeated every 4 h for a total of eight times. Approximately 2 weeks later, the drainage tube was removed from the gallbladder after cholecystography showed that no cavity other than the lumen of the tube remained in the gallbladder. RESULTS: Patients tolerated the procedure well and were followed with ultrasonography for 2-14 years (mean, 9). Twenty-nine patients had no complications or side effects, and five patients developed a 1.5- to 3- cm mucocele in the gallbladder. The long-term success rate of sclerotherapy was 85.3% (29/34). No recurrent cholecystitis, new stone or formation, canceration were encountered at the site of the gallbladder. CONCLUSIONS: Minicholecystostomy followed by chemical ablation of the gallbladder was a safe, effective, and simple procedure for treating high-risk patients with acute cholecystitis and/or cholelithiasis.

Aged↗
PubMed2005

In vitro mutation and selection of doubled-haploid Brassica napus lines with improved resistance to Sclerotinia sclerotiorum.

This paper describes a new protocol to develop doubled-haploid (DH) Brassica napus lines with improved resistance to Sclerotinia sclerotiorum. In this protocol, haploid seedlings derived from microspore cultures of B. napus were used to produce haploid calli for in vitro mutation-selection. For routine screening, mutation was induced by EMS (ethylmethane sulfonate) or occurred spontaneously, and screening for resistant mutants occurred on media with added oxalic acid (OA) as a selection agent. In tests with selected lines, the optimal concentration of EMS for mutation was determined to be 0.15%, and the optimal concentration of OA for in vitro screening was 3 mmol/l (half lethal dose was 3.1 mmol/l) for the first cycle of screening. There was an accumulated effect of OA toxicity on calli over two cycles of screening, but the growth and capacity of the surviving calli for regenerating seedlings were not affected by OA. Of the 54 DH lines produced from the in vitro mutation-selection, two DH lines of resistant mutants, named M083 and M004, were selected following seedling and glasshouse tests. The resistance of M083 and M004 to S. sclerotiorum following tests with both mycelial inoculum and OA was greater than that of their donor lines and the resistant control Zhongyou 821. In both glasshouse and field disease nurseries, disease indices on M083 and M004 were less than 50% of those of the control. The time required for M083 and M004 to mature was 14 days and 10 days shorter, respectively, than that of their donor lines. Furthermore, M083 had more pods per inflorescence, a greater 1,000 seed weight and higher yield than its donor line. Random amplified polymorphic DNA characterisation showed that M083 had DNA band patterns that differed from its donor line.

Ascomycota↗
PubMed2005

Selective alterations of gene expression in mice induced by MPTP.

1-methyl-4-phenyl-1,2,4,6,-tetrahydropyridine (MPTP) is a selective neurotoxin that produces striatal dopamine depletion resulting in parkinsonism like symptoms in humans and is, therefore, used to generate animal models for Parkinson's disease (PD). In this study, C57BL/6N mice were treated with MPTP acutely (3x20 mg/kg, 2-hour interval, one day injection). Mice were then sacrificed 24 hours after the last injection and brain tissue was collected for analysis. Significant decrease of striatal dopamine (DA) and the metabolites (DOPAC, HVA) was observed after MPTP treatment. MPTP also reduced protein expression of tyrosine hydroxylase (TH) in the striatum. Real time RT-PCR was used to examine selective genes of the dopaminergic system in the substantia nigra. Our data demonstrated that MPTP significantly decreased gene expression of TH, dopamine transporter (DAT), and vesicle monoamine transporter (VMAT), coinciding with the pattern of dopamine concentration changes and protein expression after MPTP treatment. Although a significant decrease of DA metabolites was observed in striatum, there was no change in the expression of monoamine oxidases (MAO-A, MAO-B) or catechol O-methyltransferase (COMT), indicating that these changes might be simply a consequence of reduced monoamine levels. In addition, gene expression of alpha-synuclein was also decreased with MPTP treatment, but there was no change in beta-synuclein and parkin. This is the first study using real-time PCR to indicate that MPTP selectively alters gene expression and provides information for clinical studies in PD. Future studies will focus on gene expression of other pathways that may be affected by MPTP treatment and investigation of gene expression in specific cell types in vivo using LCM technology.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2005

Selective alterations of transcription factors in MPP+-induced neurotoxicity in PC12 cells.

MPP(+) (1-methyl-4-phenylpyridinium; the active metabolite of the neurotoxin MPTP (1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine)) depletes dopamine (DA) content and elicits cell death in PC12 cells. However, the mechanism of MPP(+)-induced neurotoxicity is still unclear. In this study, the dose response and time-course of MPP(+)-induced DA depletion and decreased cell viability were determined in nerve growth factor (NGF)-differentiated PC12 cells. The alteration of transcription factors (TFs) induced by MPP(+) from a selected dose level and time point was then evaluated using protein/DNA-binding arrays. K-means clustering analysis identified four patterns of protein/DNA-binding changes. Three of the 28 TFs identified in PC12 cells increased by 100% (p53, PRE, Smad SBE) and 2 decreased by 50% (HSE, RXR(DR1)) of control with MPP(+) treatment. In addition, three TFs decreased within the range of 33-50% (TFIID, E2F1, CREB) and two TFs increased within the range of 50-100% (PAX-5, Stat4). An electrophoretic mobility shift assay (EMSA) was used to confirm the changes of p53 and HSE. The observed changes in TFs correlated with the alterations of DA and cell viability. The data indicates that selective transcription factors are involved in MPP(+)-induced neurotoxicity and it provides mechanistic information that may be applicable to animal studies with MPTP and clinical studies of Parkinson's disease.

1-Methyl-4-phenylpyridinium↗
PubMed2005

OsAGAP, an ARF-GAP from rice, regulates root development mediated by auxin in Arabidopsis.

Arf (ADP-ribosylation factor) proteins, which mediate vesicular transport, have little or no intrinsic GTPase activity. They rely on the action of GTPase-activating proteins (GAPs) and guanine nucleotide exchange factors (GEFs) for their function. In the present study the OsAGAP gene in rice, which encoded a protein with predicted structure similar to ArfGAP, was identified. The purified OsAGAP-GST fusion protein was able to stimulate the GTPase activity of rice Arf. Furthermore, OsAGAP can rescue the defect of vesicular transport in the yeast gcs1 delta glo3 delta double-mutant cells. Transgenic Arabidopsis with OsAGAP constitutively expression showed reduced apical dominance, shorter primary roots, increasing number of longer adventitious roots. Many of the phenotypes can be phenocopied by treatment of exogenous indoleacetic acid level (IAA) in wild-type plants. Determination of whole-plant IAA level showed that there is a sharp increase of free IAA in OsAGAP transgenic Arabidopsis seedlings. In addition, removal of the 4-day-old shoot apex could inhibit the adventitious root formation in the transgenic seedlings. These results suggest OsAGAP, an ARF-GAP of rice, maybe involved in the mediation of plant root development by regulating auxin level.

ADP-Ribosylation Factors↗
PubMed2005

Expression of granulocyte colony stimulating factor receptor in human colorectal cancer.

AIMS: To discover if human colorectal cancer expresses granulocyte colony stimulating factor receptor (G-CSFR) and if granulocyte colony stimulating factor (G-CSF) plays an important part in the development and progression of human colorectal cancer. METHODS: Forty two specimens of colorectal cancer and normal colorectal mucosa were investigated, taken from the colon or rectum in group of colorectal cancer patients. Immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) technique were used to show G-CSFR expression. The relation between expression of G-CSFR and clinical or pathological factors was analysed. RESULTS: Immucohistochemical analyses showed that G-CSFR was expressed in the human colorectal cancer (25 of 42, 59.52%) and seemed to be up-regulated compared with the normal mucosa (14 of 42, 33.33%, p<0.001). In pronounced contrast with mostly strongly positive tumours, corresponding normal colorectal mucosa was negative or weakly positive. A significant correlation was found between G-CSFR expression and tumour stage (p = 0.001), tumour differentiation (p<0.001), but there was no significant relation between the expression of G-CSFR and the age, sex, and tumour size (p = 0.346, p = 0.686, p = 0.459). In RT-PCR, 21 of all 42 tumours had G-CSFR mRNA expression, while only 11 of 42 normal colorectal mucosa had such expression. CONCLUSIONS: These data show that G-CSFR is commonly expressed in human colorectal cancers, thus supporting a possible role for G-CSF in colorectal cancer physiology.

Adolescent↗
PubMed2005

Developmental gene expression of lactoferrin and effect of dietary iron on gene regulation of lactoferrin in mouse mammary gland.

This study evaluated the developmental gene expression of lactoferrin (LF) and the effect of supplementary iron on gene expression of LF in the mammary gland of mice using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis. In experiment 1, a total of 12 female mice were used to determine the effect of different lactating stages on mRNA expression of LF. The Institute of Cancer Research mice were divided into 4 groups; each group of 3 mice was tested on d 1, 9, 17, and 25 of lactation. In experiment 2, 6 groups of mice (total of 24 female mice at d 12 after mating) were fed purified diets (without iron or supplement iron) and were assigned to 2 treatments (control and treatment). The experimental feeding period lasted 35 d. During the feeding experiment, 6 mice (3 animals in each group) were chosen on d 1, 9, 17, and 25 of lactation to determine the effect of iron on LF mRNA expression of mice at different stages of lactation. The results of experiment 1 showed that LF mRNA had strong expression on d 1 of lactation, decreased gradually on d 9 and 17 of lactation, and then increased again markedly on d 25 of lactation. These results imply that the expression of LF in the mammary gland at different lactating stages is consistent with the changes in LF concentrations in milk. Iron significantly increased LF mRNA expression on d 1 and 25 of lactation. Iron did not statistically increase LF gene expression on d 9 and 17 of lactation. These findings raised the possibility that iron supplementation may play a role in regulation of LF levels in vivo.

Animals↗
PubMed2005

Performance of two hearing screening protocols in the NICU.

We recently started a hearing screening program for the newborns of the neonatal intensive care unit (NICU) of Shanghai Children's Medical Center. The program consisted of a two-step screening stage using DPOAE and automated ABR (AABR) at the age of a few days, and a diagnostic stage including otoscopy, measuring middle ear impedance and click evoked ABR at the age of two months. Babies who were referred on either the basis of DPOAE or DPOAE-AABR screening were referred for diagnostic work-up. Of the 200 NICU infants, twenty-nine (14.5%) were referred by a single session DPOAE screening. Of these, nine (4.5%) were identified by the DPOAE-AABR screening. At the age of two months, six NICU babies (3%) had a significant hearing loss based on click-evoked ABR. None of the infants who were referred by DPOAE but had passed the AABR screening were found to have actual hearing loss. Our study reports the successful implementation of a two-step screening protocol for 'at risk' babies in Shanghai. We hope that our efforts represent a first step towards the implementation of universal hearing screening throughout the People's Republic of China.

China↗
PubMed2005

Optimization of Suzhou Creek Rehabilitation Project Stage I.

Suzhou Creek is a seriously polluted tidal river in Shanghai, China. With the development of Shanghai, there is more and more concern over the "blackness and stink" phenomenon of Suzhou Creek. Suzhou Creek Rehabilitation Project was launched in 1998, and the planning investment of the Project Stage I was 8.65 billion yuan (about 1.05 billion US dollars). It is important to predict the effectiveness of the project and to optimize it. In this study, the USEPA's WASP model is employed to establish a water quality model of Suzhou Creek by using data from the Third Trial Low Flow Augmentation on Suzhou Creek in 1999 and other monitoring results. Based on this, Suzhou Creek Rehabilitation Project Stage I is optimized and adjusted, so the actual investment of the Project Stage I is reduced to 6.99 billion yuan. By implementing the Project Stage I, the targets of Stage I have been met, the "blackness and stink" phenomenon of the mainstream was eliminated by the end of 2000, and the ecological system was improved step by step.

China↗
PubMed2004

Coding of acoustic particle motion by utricular fibers in the sleeper goby, Dormitator latifrons.

It is unknown whether the fish utricle contributes to directional hearing. Here, we report response properties of single utricular fibers in a teleost fish ( Dormitator latifrons) to linear accelerations at various stimulus frequencies and axes. Characteristic frequencies ranged from < or =50-400 Hz (median=80 Hz), and best frequencies shifted from 50 to 250 Hz with stimulus level. Best sensitivity of utricular fibers was distributed from -70 to -40 dB re: 1 g (mean=-52 dB), which is about 30 dB less sensitive than saccular fibers. Q50% fell between 0.16 and 11.50 (mean=2.04) at 15 dB above threshold. We observed temporal response patterns of entrained phase-locking, double phase-locking, phase-locked bursting, and non-phase-locked bursting. Most utricular fibers were directionally selective with various directional response profiles, and directional selectivity was stimulus-level dependent. Horizontal best-response axes were distributed in a 152 degrees range while mid-sagittal best-response axes were clustered around the fish longitudinal axis, which is consistent with the horizontal orientation of the utricle and morphological polarizations of utricular hair cells. Therefore, results of this study indicate that the utricle in this vertebrate plays an auditory role in azimuth and that utricular fibers extend the response dynamic range of this species in directional hearing.

Acceleration↗
PubMed2004

Brain C-FOS expression and pressor responses after I.V. or I.C.V. angiotensin in the near-term ovine fetus.

Fetal brain c-fos and cardiovascular responses after i.v. or i.c.v. angiotensin II administrations was determined in the near-term ovine fetuses. Both routes of angiotensin II markedly increased fetal mean arterial pressure. The latency of pressor responses by i.v. angiotensin II administration was shorter than by the i.c.v. route. The increased fetal mean arterial pressure was greater and transient by the i.v. route in comparison to that caused by i.c.v. angiotensin II administration. Following the i.v. administration of angiotensin II, the fetal heart rate was significantly decreased. Associated with fetal pressor responses and bradycardia, c-fos expression induced by i.v. angiotensin II was in the paraventricular nuclei (PVN) of the hypothalamus, and the area postrema, the tractus solitarius nuclei, and the lateral parabrachial nuclei in the brain stem. After i.c.v. angiotensin II administration, fetal blood pressure was also increased in association with the intensive c-fos expression in the PVN and the hindbrain. However, fetal heart rate was not affected by the central injection of angiotensin II. These results indicate that the central pathways between the forebrain circumventricular organs and the PVN have developed, and suggest that the neural activity in the hindbrain associated with bradycardia may be linked to the baroreflex. In the face of i.c.v. angiotensin II, sympathetic activation may play a predominant role in pressor responses. Taken together, these results suggest that central and peripheral angiotensin II-induced fetal pressor responses may be mediated by separate mechanisms, and these regulatory mechanisms start to function by near-term or early.

Angiotensin II↗
PubMed2004

A new keratin 5 mutation (K199T) in a family with Weber-Cockayne epidermolysis bullosa simplex.

A new missense mutation in the keratin 5 gene (KRT5) in a Chinese family with Weber-Cockayne type epidermolysis bullosa simplex is reported. Direct sequencing identified a heterozygous A --> C substitution at nucleotide 596 altering codon 199 of KRT5 from lysine to threonine in all affected family members, but not in the unaffected family members or in 50 unrelated control samples. The mutation is designated K199T. This mutated lysine residue is sited within the 1A domain of keratin 5 and is highly conserved among all type II keratins. The mutation may perturb the alignment of tonofilaments and, as a consequence, result in skin fragility and blistering.

Adult↗
PubMed2004

Mutations in SCN9A, encoding a sodium channel alpha subunit, in patients with primary erythermalgia.

Primary erythermalgia is a rare autosomal dominant disease characterised by intermittent burning pain with redness and heat in the extremities. A previous study established the linkage of primary erythermalgia to a 7.94 cM interval on chromosome 2q, but the causative gene was not identified. We performed linkage analysis in a Chinese family with primary erythermalgia, and screened the mutations in the two candidate genes, SCN9A and GCA, in the family and a sporadic patient. Linkage analysis yielded a maximum lod score of 2.11 for both markers D2S2370 and D2S2330. Based on critical recombination events in two patients in the family, we further limited the genetic region to 5.98 cM between D2S2370 and D2S2345. We then identified two missense mutations in SCN9A in the family (T2573A) and the sporadic patient (T2543C). Our data suggest that mutations in SCN9A cause primary erythermalgia. SCN9A, encoding a voltage-gated sodium channel alpha subunit predominantly expressed in sensory and sympathetic neurones, may play an important role in nociception and vasomotor regulation.

Base Sequence↗
PubMed2003

Acoustic response properties of lagenar nerve fibers in the sleeper goby, Dormitator latifrons.

Auditory and vestibular functions of otolithic organs vary among vertebrate taxa. The saccule has been considered a major hearing organ in many fishes. However, little is known about the auditory role of the lagena in fishes. In this study we analyzed directional and frequency responses from single lagenar fibers of Dormitator latifrons to linear accelerations that simulate underwater acoustic particle motion. Characteristic frequencies of the lagenar fibers fell into two groups: </=50 Hz and 80-125 Hz. We observed various temporal response patterns: strong phase-locking, double phase-locking, phase-locked bursting, and non-phase-locked bursting. Some bursting responses have not been previously observed in vertebrate otolithic nerve fibers. Lagenar fibers could respond to accelerations as small as 1.1 mm s(-2). Like saccular fibers, lagenar fibers were directionally responsive and decreased directional selectivity with stimulus level. Best response axes of the lagenar fibers clustered around the lagenar longitudinal axis in the horizontal plane, but distributed in a diversity of axes in the mid-sagittal plane, which generally reflect morphological polarizations of hair cells in the lagena. We conclude that the lagena of D. latifrons plays a role in sound localization in elevation, particularly at high stimulus intensities where responses of most saccular fibers are saturated.

Acoustic Stimulation↗
PubMed2003

Scanning tunnelling microscopy imaging of [3 x 3] Mn nonanuclear grids.

The scanning tunnelling microscopy imaging of [3 x 3] Mn(II) nonanuclear grids on gold substrates is described. Self-assembled behaviour is observed at both high and low coverage, with submolecular resolution of individual molecules displayed at low deposition concentrations. The importance of proper image processing techniques is demonstrated in resolving the layer structure at high coverage.

Gold↗
PubMed2003

Inhibition of the CD28-CD80 co-stimulation signal by a CD28-binding affibody ligand developed by combinatorial protein engineering.

CD28 is one of the key molecules for co-stimulatory signalling in T cells. Here, novel ligands (affibodies) showing selective binding to human CD28 (hCD28) have been selected by phage display technology from a protein library constructed through combinatorial mutagenesis of a 58-residue three-helix bundle domain derived from staphylococcal protein A. Analysis of selected affibodies showed a marked sequence homology and biosensor analyses showed that all investigated affibodies bound to hCD28 with micromolar affinities (KD). No cross-reactivity towards the related protein human CTLA-4 could be observed. This lack of cross-reactivity to hCTLA-4 suggests that the recognition site on hCD28 for the affibodies resides outside the conserved MYPPPYY motif. The apparent binding affinity for hCD28 could be improved through fusion to an Fc fragment fusion partner, resulting in a divalent presentation of the affibody ligand. For the majority of selected anti-CD28 affibodies, in co-culture experiments involving Jurkat T-cells and CHO cell lines transfected to express human CD80 (hCD80) or LFA-3 (hLFA-3) on the cell surface, respectively, pre-incubation of Jurkat cells with affibodies resulted in inhibition of IL-2 production when they were co-cultured with CHO (hCD80+) cells, but not with CHO (hLFA-3+) cells. For one affibody variant denoted Z(CD28:5) a clear concentration-dependent inhibition was seen, indicating that this affibody binds hCD28 and specifically interferes in the interaction between hCD28 and hCD80.

Amino Acid Sequence↗
PubMed2003

Zinc accumulation in N-methyl-N-nitrosourea-induced rat mammary tumors is accompanied by an altered expression of ZnT-1 and metallothionein.

Zinc is essential for cell proliferation. Several human studies have shown that in breast cancer tissues, zinc concentration expressed on a per tissue weight basis is higher than that in normal breast tissues. However, the mechanisms involved are unknown. N-methyl-N-nitrosourea (MNU)-induced rat mammary tumorigenesis is one of the most widely used rodent mammary tumorigenesis models for studying human breast cancer due to their similarities in hormone dependency, pathogenesis, histological classification, and immunocytochemical markers. This study was to establish if there was an accumulation of zinc in MNU-induced rat mammary tumors and, if there was, to explore the possible mechanisms involved. Sprague-Dawley rats were sham-treated or MNU-treated (50 mg/kg; n = 12) for 100 days. In MNU-induced mammary tumors (mammary tumors), zinc concentration expressed on a per dry weight basis was 12 times of that in normal mammary glands. Moreover, the mRNA level of ZnT-1 (a transporter involved in zinc efflux) in mammary tumors was reduced by 55% as compared with that in normal mammary glands. The mRNA level of Nramp2 (a divalent cation importer) and ZnT-4 (another transporter involved in zinc efflux) was unaffected by MNU-induced mammary tumorigenesis. The mRNA and protein levels of metallothionein (a putative zinc storage protein) in mammary tumors were 1.3 and 3.5 times of that in normal mammary glands, respectively. Collectively, our observations showed that zinc is accumulated in MNU-induced rat mammary tumors and this accumulation is accompanied by an altered expression of ZnT-1 and metallothionein, suggesting that zinc homeostasis might be altered in MNU-induced rat mammary tumorigenesis. Because zinc is essential to cell proliferation and cell proliferation is increased in mammary tumors, zinc accumulation is likely a part of an integrated effort to ensure sufficient zinc supply to sustain tumor growth.

Animals↗