Biomedical subjects

X Xu

Publications and source records attributed to X Xu.

At least 487 records · Page 27Linked to original sources

PubMed1999

Potential regulation of membrane trafficking by estrogen receptor alpha via induction of rab11 in uterine glands during implantation.

The steroid hormone estrogen profoundly influences the early events in the uterus leading to embryo implantation. It is thought that estrogen triggers the expression of a unique set of genes in the preimplantation endometrium that in turn control implantation. To identify these estrogen-induced genes, we used a delayed implantation model system in which embryo attachment to endometrium is dependent on estrogen administration. Using a mRNA differential display (DD) method, we isolated a number of cDNAs representing mRNAs whose expression is either turned on or turned off in response to an implantation-inducing dose of estrogen. We identified one of these cDNAs as that encoding rab11, a p21ras-like GTP-binding protein (G protein), which functions in the targeting of transport vesicles to the plasma membrane. In normal pregnant rats, rab11 mRNA was expressed at low levels on days 1-2 of pregnancy, but its expression was markedly enhanced (approximately 6- to 8-fold) between days 3-5 immediately before implantation. In situ hybridization and immunocytochemistry revealed that rab11 expression in the uterus was predominantly in the glandular epithelium. In ovariectomized rats, the expression of rab11 mRNA was induced in the endometrium in response to estrogen. To determine whether this effect of estrogen was mediated through its nuclear receptors, we examined rab11 expression in a transformed endometrial cell line, Ishikawa. In transient transfection experiments, we observed that overexpression of estrogen receptor (ER) alpha or beta induced endogenous rab11 mRNA in a hormone-dependent manner. ER bound to an antagonist, ICI 182,780, failed to activate this gene expression. These findings, together with the observation that ER alpha but not ER beta is detected in the glands of the preimplantation uterus, indicate that rab11 is one of the proteins that are specifically induced by estrogen-complexed ER alpha in rat endometrium at the onset of implantation. Our results imply that estrogen, which induces the synthesis of many growth factors and their receptors and other secretory proteins that are thought to be critical for implantation, may also facilitate their transport to the membrane and/or secretion by stimulating the expression of rab11, a component of the membrane-trafficking pathway. This study therefore provides novel insights into the diverse cellular mechanisms by which estrogen, acting via its nuclear receptors, may influence blastocyst implantation.

Animals↗

PubMed1999

Angiogenesis defects and mesenchymal apoptosis in mice lacking SMAD5.

The transforming growth factor-beta (TGF-beta) signals are mediated by a family of at least nine SMAD proteins, of which SMAD5 is thought to relay signals of the bone morphogenetic protein (BMP) pathway. To investigate the role of SMAD5 during vertebrate development and tumorigenesis, we disrupted the Smad5 gene by homologous recombination. We showed that Smad5 was expressed predominantly in mesenchyme and somites during embryogenesis, and in many tissues of the adult. Mice homozygous for the mutation died between days 10.5 and 11.5 of gestation due to defects in angiogenesis. The mutant yolk sacs lacked normal vasculature and had irregularly distributed blood cells, although they contained hematopoietic precursors capable of erythroid differentiation. Smad5 mutant embryos had enlarged blood vessels surrounded by decreased numbers of vascular smooth muscle cells, suffered massive apoptosis of mesenchymal cells, and were unable to direct angiogenesis in vitro. These data suggest that SMAD5 may regulate endothelium-mesenchyme interactions during angiogenesis and that it is essential for mesenchymal survival.

Animals↗

PubMed1999

Murine protein kinase CK2: gene and oncogene.

Protein kinase CK2 (casein kinase II) is a serine-threonine protein kinase with a wide range of substrates, many of which are involved in cell cycle regulation. CK2 activity is elevated in a variety of human tumors and we have used a transgenic mouse model to demonstrate that dysregulated expression of CK2 can induce lymphoma. Thus, CK2 fulfills the definition of an oncogene: A mutated, dysregulated, or mis-expressed gene that contributes to cancer in a dominant fashion. CK2 cooperates in transforming cells with other lymphoid oncogenes such as myc and tal-1, and here we show cooperativity with loss of the tumor suppressor gene p53. To understand more about the physiological and pathological role of CK2, we are cloning the murine CK2alpha' cDNA and gene. CK2alpha' will be used to generate transgenic and knockout mice and the regulatory elements for gene expression will be analyzed.

Amino Acid Sequence↗

PubMed1999

[Rapid detection of non-deletional alpha-thalassemia mutations by PCR-LIS-SSCP].

OBJECTIVE: To establish a rapid and convenient single strand conformation polymorphism (SSCP) analysis method for detecting the point mutation of non-deletional alpha-thalassemia. METHODS: The 543bp DNA fragment spanning the hot spot region mainly responsible for non-deletional alpha-thalassemia was nested amplified using the selective amplification of alpha2 globin gene as a template and was denatured with low ionic strength(LIS) solution followed by SSCP analysis. RESULTS: LIS buffer was more efficient for ssDNA formation than formamide buffer was and the formation of ssDNA was very stable. In addition to a normal electrophoresis pattern, at least three SSCP profiles can be detected by the present method when the DNA samples bearing non-deletional genes of Hb H disease were screened. Confirmed by DNA sequencing analysis, the DNAs represented these profiles have turned out to be the different three mutants, i.e., the alpha&supCS; mutation, the alpha &supQS; mutation and the alpha&supWestmead; mutation, respectively. Only 3 hours were needed to complete the electrophoresis procedure of this method. CONCLUSION: PCR-LIS-SSCP can be used as a tool in rapid screening for the alterations in human alpha-globin gene.

Humans↗

PubMed1999

Nonpredictable pharmacokinetic behavior of high-dose cyclophosphamide in combination with cisplatin and 1,3-bis(2-chloroethyl)-1-nitrosourea.

Our objective was to assess whether the total area under the curve (AUC) of high-dose cyclophosphamide (CPA), combined with cisplatin and 1,3-bis(2-chloroethyl)-1-nitrosourea, could be predicted from its AUC on the first day of treatment. We reviewed the AUC of CPA in 470 patients who underwent pharmacokinetic monitoring of the drug. All patients received the same high-dose regimen of CPA, cisplatin, and 1,3-bis(2-chloroethyl)-1-nitrosourea (STAMP-I) with identical antiemetic support. Subsequently, patients who experienced a toxic death, relapsed after high-dose chemotherapy, or remained relapse-free at a minimum follow-up of 1 year after high-dose chemotherapy were analyzed for a correlation between the total AUC of CPA and both relapse-free survival and toxic death. The AUC of CPA decreased from day 1 to day 2 in most patients. However, its changes from day 2 to day 3 varied significantly. Neither the value of AUC on day 1 nor its decreasing trend from day 2 to day 3 could predict the AUC on day 3 and the total AUC. Our pharmacodynamic analysis in 335 patients failed to show a correlation between the total AUC of CPA and either toxic death or relapse-free survival. The significant intersubject variability in the AUC of CPA makes the final AUC of the drug unpredictable from an initial measurement on day 1. Thus, in this combination, measurement of levels of parent CPA, with the objective of real-time therapeutic monitoring of this drug, is not informative.

Analysis of Variance↗

PubMed1999

[Capillary free zone electrophoresis of globin chains].

OBJECTIVE: To introduce a new technique for rapid separation of globin chains from clinical samples. METHODS: The authors used the uncoated capillary and the electrophoresis buffer which contained 100mmol/L NaH2PO4 +7mmol/L urea +1% Triton X-100 +1% 2-mercaptoethanol +0.25% PEG-600. Capillary free zone electrophoresis was employed in analyzing the hemoglobin-water solutions which were made from HbA control and 74 clinical blood samples. The globin chains were separated from the samples. RESULTS: IN 40 minutes, five globin chains: alpha, beta, Ggamma, delta, Agamma were separated clearly by capillary free zone electrophoresis using nanolitres of sample. In electrophoresis figure the baselines were stable and the peaks were clear. The time coefficient of variation (CV) was under 3%, and the area CV below 4%. Also, The authors measured the relative concentration of globin chains from 60 normal cases and 14 thalassemia patients. CONCLUSION: The capillary free zone electrophoresis for the separation of globin chains from clinical samples has been successfully achieved. It is a rapid, simple and sensitive technique suitable for rapid diagnosis of hemoglobinopathies.

Adult↗

PubMed1999

Characterization of a mouse Cx50 mutation associated with the No2 mouse cataract.

PURPOSE: Recently, a missense mutation in the mouse connexin 50 (Cx50) gene has been associated with the nuclear opacity 2 (No2) mouse cataract. This missense mutation (D47A) resulted in an aspartate-to-alanine substitution at amino acid position 47 in the first extracellular domain of Cx50. To better understand the role of Cx50 in the pathogenesis of congenital cataract, the functional consequences of the D47A mutation in the Xenopus oocyte expression system were studied. METHODS: D47A was constructed using polymerase chain reaction (PCR) mutagenesis. Xenopus oocytes were injected with in vitro transcribed cRNA encoding wild-type mouse Cx50 (Cx50wt), wild-type rat Cx46 (Cx46wt), D47A, or combinations of wild-type and mutant connexins. The oocytes were then devitellinized and paired. Gap junctional conductance (Gj) was measured using a dual two-microelectrode voltage-clamp technique. RESULTS: Homotypic oocyte pairs expressing wild-type Cx50 or Cx46 were well coupled. In contrast, oocytes injected with D47A cRNA did not form gap junctional channels when paired homotypically. To test whether the D47A mutation could interact with wild-type connexins in a dominant negative manner, oocytes were injected with equal amounts of mutant and wild-type connexin cRNA, mimicking the heterozygous condition. Expression of D47A did not inhibit the development of junctional conductance in paired oocytes induced by wild-type Cx50 or Cx46. CONCLUSIONS: These results indicate that the D47A mutation acts as a loss-of-function mutation without strong dominant inhibition. In No2 mice, the mutation would be predicted to result in a reduction in intercellular communication, leading to cataractogenesis. It may also cause other qualitative changes such as a change in permeability for small molecules.

Animals↗

PubMed1999

A 12-Mb complete coverage BAC contig map in human chromosome 16p13.1-p11.2.

We have constructed a complete coverage BAC contig map that spans a 12-Mb genomic segment in the human chromosome 16p13.1-p11.2 region. The map consists of 68 previously mapped STSs and 289 BAC clones, 51 of which-corresponding to a total of 7.721 Mb of genomic DNA-have been sequenced, and provides a high resolution physical map of the region. Contigs were initially built based mainly on the analysis of STS contents and restriction fingerprint patterns of the clones. To close the gaps, probes derived from BAC clone ends were used to screen deeper BAC libraries. Clone end sequence data obtained from chromosome 16-specific BACs, as well as from public databases, were used for the identification of BACs that overlap with fully sequenced BACs by means of sequence match. This approach allowed precise alignment of clone overlaps in addition to restriction fingerprint comparison. A freehand contig drawing software tool was developed and used to manage the map data graphically and generate a real scale physical map. The map we present here is approximately 3.5 x deep and provides a minimal tiling path that covers the region in an array of contigous, overlapping BACs.

Base Sequence↗

PubMed1999

Identification of a novel intron and 4 polymorphisms in the gene encoding the gamma subunit of the epithelial sodium channel.

The amiloride-sensitive epithelial sodium channel is a highly selective sodium channel that constitutes the rate-limiting step of sodium reabsorption in distal nephrons. It consists of at least 3 subunits (alpha, beta, and gamma) of similar structure and plays an important role in sodium and fluid homeostasis. Defects of this channel have been critically implicated in Liddle syndrome (pseudoaldosteronism) and pseudohypo-aldosteronism type 1. A sample of 48 individuals from 23 nuclear families was selected from Anhui, China. We sequenced 12 exons and flanking intronic sequences and discovered a new 207-bp intron located in the previously described exon X of Thomas et al. (1996). In addition, 4 novel single nucleotide polymorphisms were identified; 3 were in exon 3 and 1 was in exon 13. Furthermore, 2 base substitutions in exon 13 were present in all the Chinese subjects compared with the published European SCNN1G DNA sequence.

Base Sequence↗

PubMed1999

[Cloning and expression analyses of down-regulated cDNA C6-2A in human esophageal cancer].

OBJECTIVE: To clone genes associated with the genesis of human esophageal cancer. METHODS: Identifying missing or low expressing cDNAs in human esophageal cancer tissues by mRNA differential display and examining its mRNA expression in 4 human cancer cell lines, 9 fetal tissues and other matched esophageal cancer tissues by Northern blot, dot blot and RT-PCR. RESULTS: One cDNA fragment named C6-2A, was cloned and sequenced. There was no identical sequence with C6-2A in BLASTN database; but in querying Genbank EST, the authors found that C6-2A was identical with ne27b03.s1NCI-CGAP-C03 humans sapiens cDNA clone IMAGE:898541 3' and zv30g07.rl Soares ovary tumor NbHOT homo sapiens cDNA clone 755196. 6/6 esophageal cancer tissues in Northern blot and 7/8 in dot blot did not or slightly express C6-2A. RT-PCR analysis showed that C6-2A was expressed much lower in 17/20 esophageal cancer tissues than adjacent microscopically normal mucosa, highly expressed in fetal esophageal mucosa, skin, cerebrum, placenta; moderately expressed in fetal stomach and liver, but not detected in fetal heart, small intestine and kidney. CONCLUSION: The high frequency of deletion of decreased expression of C6-2A in esophageal cell lines and human esophageal cancer tissues suggested that C6-2A might be involved in the carcinogenesis of esophagus.

Cloning, Molecular↗

PubMed1999

A predictive model for relapse in high-risk primary breast cancer patients treated with high-dose chemotherapy and autologous stem-cell transplant.

High-dose chemotherapy (HDCT) is currently under evaluation for high-risk primary breast cancer (HRPBC), defined by extensive axillary nodal involvement or inflammatory breast carcinoma. Phase II studies of HDCT for HRPBC show that 30-40% of patients eventually relapse. We retrospectively reviewed 176 patients enrolled in clinical trials of HDCT for HRPBC at the University of Colorado and analyzed 23 potential predictive variables for relapse. All of the patients received the same regimen, with cyclophosphamide, cisplatin, and BCNU. Nine patients who experienced a toxic death were excluded from this analysis. The resulting predictive model was subsequently tested in an independent patient set treated at Duke University with the same HDCT regimen. Nodal ratio (number of involved nodes:number of sampled nodes), tumor size, grade, stage, estrogen receptor, progesterone receptor, and clinical inflammatory breast carcinoma correlated with risk of relapse. Nodal ratio, tumor size, and the combined estrogen receptor/progesterone receptor status were independent predictors. A scoring system using those three variables determines the risk of relapse, with a sensitivity and specificity of 60 and 90%, respectively, and a positive and negative predictive value of 65 and 88%, respectively. The differences in relapse-free survival and overall survival between high- and low-score patients were highly significant (P<0.000001). This model was subsequently validated in the Duke patient set. This model can identify two subgroups of HRPBC patients with low (12%) and high (65%) risk for recurrence after HDCT. Future research that tests new therapies will focus on those patients with a high score.

Adult↗

PubMed1999

Immersion of distal arms and legs in warm water (AVA rewarming) effectively rewarms mildly hypothermic humans.

INTRODUCTION: Active rewarming of hypothermic victims for field use, and where transport to medical facilities is impossible, might be the only way to restore deep body temperature. In active rewarming in warm water, there has been a controversy concerning whether arms and legs should be immersed in the water or left out. Further, it has been suggested in the Royal Danish Navy treatment regime, that immersion of hands, forearms, feet, and lower legs alone might accomplish rapid rates of rewarming (AVA rewarming). METHODS: On three occasions, six subjects (one female) were cooled in 8 degrees C water, to an esophageal temperature of 34.3+/-0.8 (+/-SD) degrees C. After cooling the subjects were warmed by shivering heat production alone, or by immersing the distal extremities (hands, forearms, feet and lower legs) in either 42 degrees C or 45 degrees C water. RESULTS: The post cooling afterdrop in esophageal temperature was decreased by both 42 degrees C and 45 degrees C water immersion (0.4+/-0.2 degrees C) compared with the shivering alone procedure (0.6+/-0.4 degrees C; p < 0.05). The subsequent rate of rewarming was significantly greater with 45 degrees C water immersion (9.9+/-3.2 degrees C x h(-1)) than both 42 degrees C water immersion (6.1+/-1.2 degrees C x h(-1)) and shivering alone (3.4+/-1.5 degrees C x h(-1); p < 0.05). CONCLUSION: The extremity rewarming procedure was experienced by the subjects as the most comfortable as the rapid rise in deep body temperature shortened the period of shivering. During the extremity rewarming procedures the rectal temperature lagged considerably behind the esophageal and aural canal (via indwelling thermocouple) temperatures. Thus large gradients may still exist between body compartments even though the heart is warmed.

Adult↗

PubMed1999

Assays of ligand-human serum albumin binding using pulsed ultrafiltration and liquid chromatography-mass spectrometry.

Two approaches were utilized to increase the throughput of pulsed ultrafiltration assays of ligand binding to human serum albumin, reducing the volume of the ultrafiltration chamber and combining pulsed ultrafiltration with high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-MS). Affinity constants for binding of ligands to human serum albumin were determined using pulsed ultrafiltration with ultraviolet absorbance detection. The first affinity constants (Ka1) were measured for the binding of dansylsarcosine, dansylamide, 7-anilinocoumarin-4-acetic acid and warfarin, and were determined to be 1.8 x 105, 5 x 104, 8 x 104, and 2.0 x 105 M-1, respectively. The throughput of pulsed ultrafiltration analyses was tripled compared to previous pulsed ultrafiltration measurements by reducing the volume of the chamber. In addition, the use of LC-MS with pulsed ultrafiltration permitted the simultaneous comparison and rank ordering of ligand mixtures for binding to serum albumin. For example, the throughput of these pulsed ultrafiltration measurements was tripled by analyzing three ligands as a mixture.

Chromatography, Liquid↗

PubMed1999

311 cases of chronic osteomyelitis treated by soaking with ganlingsan liquid.

From 1992 to 1995, 311 cases of chronic osteomyelitis (including 145 cases of hematogenic osteomyelitis, 147 cases of traumatic osteomyelitis, 8 cases of secondary osteomyelitis after local infection, 4 cases due to other causes, and 7 cases with cause unknown) were treated by soaking with Ganlingsan liquid. The average treatment course was 69.5 days. The results showed that 260 cases were cured, 26 cases markedly effective, 20 cases improved, and 5 cases ineffective. The evaluation of the function revealed that 150 cases were excellent, 129 cases good, 10 cases improved, and 22 cases poor. 111 patients recovered from abnormal erythrocyte sedimentation rate. External fixation was applied at the same time for the patients accompanied by nonunion of fracture, and the therapeutic effect was also satisfactory.

Administration, Topical↗

PubMed1999

Treatment of epiphora due to insufficiency of lacrimal passage by acupuncture at Jingming.

Since 1995, the authors have employed acupuncture at Jingming (UB 1) with the warming needles to treat epiphora due to insufficiency of lacrimal passages. Of the 68 treated eyes in 42 patients, 28 eyes were cured, 35 improved, and 5 ineffective with a total effective rate of 92.65%; and 12 eyes were cured and 34 improved by only one course of treatment.

Acupuncture Points↗

PubMed1999

[A large-scale study on the safety and epidemiological efficacy of Japanese encephalitis (JE) live vaccine (SA14-14-2) in the JE endemic areas].

OBJECTIVE: To measure the safety and epidemiological efficacy of Japanese encephalitis live vaccine(SA14-14-2). METHODS: Guoyang and Mengcheng counties in Anhui Province, were chosen as observed spots where high incidence of JE was noticed in China. 1-6 years old children in two counties were inoculated with vaccine manufactured by Chengdu Biological Products Institute in the beginning of 1992. All children of 1-6 years old received one primary dose of live vaccine and the children at one or two years old were respectively given one dose for primary or booster vaccination in 1993-1996. Side effects of live vaccine had been under surveillance for five years for its safety JE cases during the epidemic season (Jun to October), were diagnosed clinically and serologically. RESULTS: Data on the safety and efficacy of the JE live vaccine(SA14-14-2) are listed as follows:1) During 1992-1996, a total number, of 335,941 children at 1-6 year old were vaccinated. No vaccine-associated encephalitis, meningitis or other serious adverse events were observed. 2) The incidence of JE case has greatly declined since the beginning of large-scale vaccination. The average JE morbidity dcreased from 11.34/100,000 in 1987-1991 to 2.74/100,000 in 1992-1996(P < 0.005). 3) The incidence of JE case in 1-6 years old in that period reduced as well. The average JE morbidity decreased from 56.24/100,000 to 13.83/100,000 in Guoyang and from 44.57/100,000 to 16.94/100,000 in Mengcheng counties respectively(P < 0.005). Most of the JE cases (94%) occurred in the unvaccinated children including all the 18 death cases. 4) Serum antibody response to immunization were measured by plaque reduction neutralization test. Neutralizing antibody seroconversion after one single vaccination were 83.87%-94.74%. CONCLUSION: The results further confirmed that JE live vaccine is safe for children and effective for prevention from JE disease in JE endemic areas.

Antibodies, Viral↗

PubMed1999

[The effect of hydroxycamptothecin and topotecan to SKOV3 and CAOV3 in vitro].

OBJECTIVE: To examine the effect of hydroxycamptothecin (HCPT) and topotecan, two kinds of derivative of camptothecin, to two ovarian cancer cell lines, SKOV3 and CAOV3. METHODS: Methyl thiazolyl tetrazolium (MTT) was used to establish the dose-effect curves. The ability of these two drugs to induce apoptosis of the two cell lines was determined by the method of terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and DNA Ladder. The morphological changes of the cells were observed by electronic microscope. Expression of c-myc, bcl-2, and fas was estimated by the immunohistochemical staining. RESULTS: The inhibition of HCPT and topotecan to the growth of SKOV3 and CAOV3 was dose-dependent. 50% inhibiting concentration (IC50) of HCPT and topotecan to SKOV3 was 72 ng/ml and 160 ng/ml, respectively; IC10 of HCPT and topotecan to CAOV3 was 141 ng/ml and 12 ng/ml, respectively. The inhibition of HCPT and topotecan to clone forming rate of two cell lines was significant. The growing curves of SKOV3 and CAOV3 treated by HCPT and topotecan were significantly lower than controls. HCPT and topotecan of 5 ng/ml can elongate the double time of SKOV3 for 49.00 and 1.75 times, respectively. They can elongate the double time of CAOV3 for 2.77 and 1.94 times, respectively. After treated by HCPT or topotecan, SKOV3 generated DNA Ladder. Positive rates of TUNEL of SKOV3 and CAOV3 were elevated by HCPT and topotecan notably. HCPT and topotecan did not affect the expression of c-myc, bcl-2, fas of SKOV3 and CAOV3. Observed by electronic microscope, heterochromatin of SKOV3 and CAOV3 coagulated after treated by HCPT. Micro villi of SKOV3 and CAOV3 were damaged, and some vacuoles appeared in the cytoplasm. CONCLUSIONS: HCPT and topotecan can inhibit growth of SKOV3 and CAOV3 significantly. HCPT and topotecan can induce apoptosis of SKOV3 and CAOV3.

Antineoplastic Agents↗

PubMed1999

[Effects of stimulation of dorsal medial area and ventral medial area of nucleus facialis on myoelectric activities of genioglossus and phrenic muscle].

Effects of electrical and chemical stimulation of the dorsal and ventral medial area of nucleus facialis (dMNF and vMNF) on myoelectric activities of genioglossus and phrenic muscle were observed in 44 urethane-anaesthetized and vagotomized rabbits. The results are as follows. (1) Long train electrical stimulation at the dMNF facilitated myoelectric activities of genioglossus and phrenic muscle. (2) Short train electrical stimulation of dMNF, when delivered in the inspiratory phase, caused prolongation of myoelectric activities of genioglossus and phrenic muscle; but when delivered in the expiratory phase, myoelectric activities of genioglossus and phrenic muscle were shortened. (3) Long train electrical stimulation at the vMNF inhibited myoelectric activities of genioglossus and phrenic muscle. (4) Short train electrical stimulation of vMNF caused shortening of myoelectric activities of genioglossus and phrenic muscle, when delivered in the inspiratory phase, but a prolongation when delivered in the expiratory phase. (5) The effects of microinjection of glutamate to dMNF and vMNF were similar to those of electrical stimulation. The above results suggest that both dMNF and vMNF participate in the regulation of the myoelectric activities of genioglossus and the upper airway resistance.

Animals↗