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Biomedical subjects

Jie Xu

Publications and source records attributed to Jie Xu.

At least 37 records · Page 2Linked to original sources
PubMed2006

Subcutaneous island pedicle flap: variations and versatility for facial reconstruction.

PURPOSE: Reconstruction of facial skin defects may be a clinical challenge in respect to esthetic considerations, and the V-Y advancement island pedicle flap has been a versatile and reliable method. Besides the V-Y flap, this article is to introduce the variations of subcutaneous island pedicle flaps and their versatility for facial reconstruction. METHODS: From August 1994 to August 2005, 179 cases of medium-sized facial skin defects within 1 cosmetic unit were reconstructed with the variations of island pedicle flaps, and the length and width of the defects following removal of lesion ranged from 1.2 cm x 0.8 cm to 6.2 cm x 5.4 cm. RESULTS: Ninety-nine facial defects all over the face were reconstructed with the V-Y flaps, and the traditional and modified transposition island pedicle flaps were used to reconstruct 80 cases of relatively larger width of defects in the nose, lip, and upper cheek, especially in the young patients. Through careful planning and implementation, all flaps survived with primary healing postoperatively. With a follow-up from 6 to 30 months, well-concealed, soft, flat scars, together with good matching of the recipient sites and the flaps, were recorded. Patients and surgeons judged final overall outcome as excellent or good in 94.4% and 92.2% of evaluated patients, respectively. The main complications included visible trapdoor deformation in 9 patients, bulky flap pedicle in 8 patients, and low-grade ectropion of lower eyelid in a young boy, which all were readily revised at the second stage. Temporary alteration of sensation in the flap skin was another possible complication but usually improved with time. CONCLUSIONS: Variations of subcutaneous island pedicle flaps can be designed and may be versatile and reliable methods for esthetic reconstruction of medium-sized facial defects.

Adolescent↗
PubMed2006

Understanding HIV-related stigma and discrimination in a "blameless" population.

HIV-related stigma and discrimination are major barriers to the successful control of HIV. Stigma is associated with the disease as well as the behaviors that lead to infection. A qualitative study was conducted to identify the reasons, sources, and types of HIV-related stigma prevalent in rural China. Eighty in-depth interviews were conducted with people living with HIV/AIDS, their family members, health care providers, and uninfected villagers. Stigmatizing behaviors were primarily associated with fear of HIV rather than with the route of infection. Uninfected villagers were the main source of discrimination, with health workers and family members also holding some stigmatizing attitudes. A primary concern for HIV-positive villagers was protecting their families, especially their children, from discrimination. Secondary stigma also extended to un- infected members of the same village. The results have been used to develop an intervention to reduce fear of casual transmission and stigma in these communities.

Adolescent↗
PubMed2006

[Relationship between the absorption of dietary calcium and the Fok I polymorphism of VDR gene in young women].

OBJECTIVE: To investigate the relationship between the absorption of dietary calcium and VDR (Vitamin D(3) receptor, VDR) gene RFLPs in Chinese young women with representative diets. METHODS: Forty subjects were selected from three hundred young female students aged 18 - 23 years old. After identifying the VDR gene Fok I RFLPs, the subjects were given the representative diets during the 3-day adaptation period and the 12-day metabolism period. The copy food and drinking for measurement of nutrients and also the complete feces each day were collected. The dietary calcium absorption of each subject was examined and calculated. RESULTS: As expected, the intake of dietary calcium in subjects is close to the results set by the of National Nutrition Investigation in 1992 (from young women at 17 year old) or the daily reference intake (DRI) for adult woman; the difference of the absorption of dietary calcium among VDR gene RFLPs in young women was observed: ff < Ff < FF, (28.7 +/- 10.5)%, (30.4 +/- 15.9)% and (40.6 +/- 11.0)% respectively; only significant difference between FF genotype and Ff genotype, P < 0.05. CONCLUSION: Our results were consistent with those gained from the previous studies on children about the relationship between the absorption of dietary calcium and VDR (Vitamin D(3) receptor, VDR) gene RFLPs, and now it might occur in young women. Further studies need to be taken by using stable isotope and increasing subjects in young women.

Absorption↗
PubMed2006

[Association between hemoglobin level of children < or = 3 years and anemia of their mother].

OBJECTIVE: To study the relationship between the hemoglobin level of children < or = 3 years and anemia of their mothers. METHODS: Multi-steps cluster sampling was adopted. In order to ensure sufficient number of babies and young children and postpartum in this survey, additional subjects were included in the sample. The subjects in study were collected in the same family. RESULTS: The average anemia prevalence of children < or = 3 years was significant different between urban and rural (26.9%, 94/350 and 32.4%, 594/1835, P < 0.05) areas. The birth weight of anemia children < or = 3 years was significant lower than nonanemic children (P < 0.05); the incidence of low birth weight of anemia children < or = 3 years was significant higher than nonanemic children (P < 0.05); the percentage of Hb < 100 g/L and < 110 g/L were 7.6% (166/2185) and 24.9% (544/2185); the Hb levels of children fed by anemia mother and nonanemic mother were significantly different (115.6 +/- 17.4) g/L, (115.2 +/- 16.7) g/L and (123.3 +/- 14.9) g/L, (122.2 +/- 15.3) g/L, P < 0.001. CONCLUSION: There should be significant relation between the Hb level of children < or = 3 years and anemia of their mother.

Adult↗
PubMed2005

Nitric oxide-endothelin-1 interactions after surgically induced acute increases in pulmonary blood flow in intact lambs.

Several congenital heart defects require surgery that acutely increases pulmonary blood flow (PBF). This can lead to dynamic alterations in postoperative pulmonary vascular resistance (PVR) and can contribute to morbidity and mortality. Thus the objective of this study was to determine the role of nitric oxide (NO), endothelin (ET)-1, and their interactions in the alterations of PVR after surgically induced increases in PBF. Twenty lambs underwent placement of an aortopulmonary vascular graft. Lambs were instrumented to measure vascular pressures and PBF and studied for 4 h. Before and after shunt opening, lambs received an infusion of saline (n = 9), tezosentan, an ETA- and ETB -receptor antagonist (n = 6), or Nomega-nitro-L-arginine (L-NNA), a NO synthase (NOS) inhibitor (n = 5). In control lambs, shunt opening increased PBF by 117.8% and decreased PVR by 40.7% (P < 0.05) by 15 min, without further changes thereafter. Plasma ET-1 levels increased 17.6% (P < 0.05), and total NOS activity decreased 61.1% (P < 0.05) at 4 h. ET-receptor blockade (tezosentan) prevented the plateau of PBF and PVR, such that PBF was increased and PVR was decreased compared with controls at 3 and 4 h (P < 0.05). These changes were associated with an increase in total NOS activity (+61.4%; P < 0.05) at 4 h. NOS inhibition (L-NNA) after shunt placement prevented the sustained decrease in PVR seen in control lambs. In these lambs, PVR decreased by 15 min (P < 0.05) but returned to baseline by 2 h. Together, these data suggest that surgically induced increases in PBF are limited by vasoconstriction, at least in part by an ET-receptor-mediated decrease in lung NOS activity. Thus NO appears to be important in maintaining a reduction in PVR after acutely increased PBF.

Animals↗
PubMed2005

Insulin enhances growth hormone induction of the MEK/ERK signaling pathway.

Growth hormone (GH) plays an important role in growth and metabolism by signaling via at least three major pathways, including STATs, ERK1/2, and phosphatidylinositol 3-kinase/Akt. Physiological concentrations of insulin promote growth probably by modulating liver GH receptor (GHR) levels in vivo, but the possible effects of insulin on GH-induced post-GHR signaling have yet to be studied. We hypothesized that short-term insulin, similar to the fluctuations that occur following feeding, affects GH-induced post-GHR signaling. Our present studies suggest that, in rat H4IIE hepatoma cells, insulin (4 h or less) selectively enhanced GH-induced phosphorylation of MEK1/2 and ERK1/2, but not GH-induced activation of STAT5 and Akt. Although insulin pretreatment altered GH-induced formation of Shc.Grb2.SOS complex, it did not significantly affect GH-induced activation of other signaling intermediates upstream of MEK/ERK, including JAK2, Ras, and Raf-1. Immunofluorescent staining indicated that insulin pretreatment facilitated GH-induced cell membrane translocation of MEK1/2. Insulin pretreatment also increased the amount of MEK association with its scaffolding protein, KSR. In summary, short-term insulin treatment of cultured, liver-derived cells selectively sensitized GH-induced MEK/ERK phosphorylation independent of JAK2, Ras, and Raf-1, but likely resulted from increased cell membrane translocation of MEK1/2. These findings suggest that insulin may be necessary for sensitization of cells to GH-induced ERK1/2 activation and provides a potential cellular mechanism by which insulin promotes growth.

Animals↗
PubMed2005

Inhaled nitric oxide induced NOS inhibition and rebound pulmonary hypertension: a role for superoxide and peroxynitrite in the intact lamb.

Previous in vivo studies indicate that inhaled nitric oxide (NO) decreases nitric oxide synthase (NOS) activity and that this decrease is associated with significant increases in pulmonary vascular resistance (PVR) upon the acute withdrawal of inhaled NO (rebound pulmonary hypertension). In vitro studies suggest that superoxide and peroxynitrite production during inhaled NO therapy may mediate these effects, but in vivo data are lacking. The objective of this study was to determine the role of superoxide in the decrease in NOS activity and rebound pulmonary hypertension associated with inhaled NO therapy in vivo. In control lambs, 24 h of inhaled NO (40 ppm) decreased NOS activity by 40% (P<0.05) and increased endothelin-1 levels by 64% (P<0.05). Withdrawal of NO resulted in an acute increase in PVR (60.7%, P<0.05). Associated with these changes, superoxide and peroxynitrite levels increased more than twofold (P<0.05) following 24 h of inhaled NO therapy. However, in lambs treated with polyethylene glycol-conjugated superoxide dismutase (PEG-SOD) during inhaled NO therapy, there was no change in NOS activity, no increase in superoxide or peroxynitrite levels, and no increase in PVR upon the withdrawal of inhaled NO. In addition, endothelial NOS nitration was 18-fold higher (P<0.05) in control lambs than in PEG-SOD-treated lambs following 24 h of inhaled NO. These data suggest that superoxide and peroxynitrite participate in the decrease in NOS activity and rebound pulmonary hypertension associated with inhaled NO therapy. Reactive oxygen species scavenging may be a useful therapeutic strategy to ameliorate alterations in endogenous NO signaling during inhaled NO therapy.

Administration, Inhalation↗
PubMed2005

A QSPR treatment for the thermal stabilities of second-order NLO chromophore molecules.

Quantitative structure-property relationships were studied between descriptors representing the molecular structures and thermal decomposition temperatures (T(d)) for a diverse set of 90 second-order nonlinear optical (NLO) chromophores. A seven-parameter model was developed for the prediction of molar thermal decomposition function Y(d) (T(d) M, where M represents the molar weight) with R2 = 0.9642 and SEE = 14.01 by multilinear regression analysis. The mean relative error for the prediction of T(d) was 4.46%. The stability of the proposed model was validated using leave-one-out cross-validation. All descriptors involved in the model were derived solely from the chemical structures of the NLO chromophores.

Molecular Structure↗
PubMed2005

Identification of potent type I MetAPs inhibitors by simple bioisosteric replacement. Part 2: SAR studies of 5-heteroalkyl substituted TCAT derivatives.

Systematic SAR studies on the thiazole ring 5-substituent of TCAT derivatives revealed that the introduction of a beta-alkoxy or an amino group enhanced the inhibitory activity significantly. The present compounds are representative of specific Co(II)-MetAP1 inhibitors. Before the physiologically relevant metal ions for MetAPs are established, these small molecular compounds could be used as tools for detailed biological studies.

Alkylation↗
PubMed2005

Altered exon usage in the juxtamembrane domain of mouse and human RON regulates receptor activity and signaling specificity.

Alternative splicing of signaling proteins can contribute to the complexity of signaling networks. We find that expression of mouse RON, but not human RON, results in constitutive receptor autophosphorylation, ligand-independent activation of the mitogen-activated protein kinase pathway, and association of the receptor with c-Src. Using chimeric receptors, we mapped the region for this difference in signaling capacity of mouse and human RON to the juxtamembrane domain. Expression of these receptors in primary erythroid progenitor cells also demonstrated a functional difference in the ability of mouse and human RON to support erythropoietin-independent colony formation that mapped to the juxtamembrane domain. Splicing of the mouse RON receptor tyrosine kinase transcript results in the constitutive deletion of an exon used by all other known RON orthologs that encodes part of the juxtamembrane domain of the receptor. Mutational analysis indicated that the two tyrosines present in this region in human RON, one of which has been previously shown to be a c-Cbl binding site, are not responsible for this difference. However, deletion of this region in the context of human RON enhanced receptor phosphorylation, activation of mitogen-activated protein kinase, and association of c-Src at levels comparable with those observed with mouse RON. These data provide direct evidence that the divergence of exon usage among different species can generate a protein with novel activity and subsequently add to the complexity of cellular signaling regulation.

Alternative Splicing↗
PubMed2005

Tissue-engineered vessel strengthens quickly under physiological deformation: application of a new perfusion bioreactor with machine vision.

In order to develop a patent tissue-engineered blood vessel that grossly resembles native tissue, required culture times in most studies exceed 8 weeks. For the sake of shortening the maturation period of the constructs, we have used deformation as the basic index for mechanical environment control. A new bioreactor with a machine vision identifier was developed to accurately control the deformation of the construct during the perfusion process. Two groups of seeded constructs (n = 4 per group) were investigated in this study, with one group stimulated by a cyclic deformation of 10% and the other by a pulsatile pressure that gradually increased to 120 mm Hg (the control group). After 21 days of culture, the mechanical properties of the constructs were examined. The average burst strength and suture retention strength in the two groups were significantly different (t test, p < 0.05). For the experimental group, the average burst strength and suture retention strength were higher than those of the control group, by 31.6 and 23.4%, respectively. Specifically, the average burst strength of the constructs reached 1,402 mm Hg (close to that of the native vessel, i.e. 1,680 mm Hg) within a relatively short period of 21 days. In conclusion, deformation is an observable, controllable and very valuable index for mechanical environment control in vascular tissue engineering. It makes the control of mechanical stimuli more essential and experiments more comparable.

Animals↗
PubMed2005

Regulation of hunger-driven behaviors by neural ribosomal S6 kinase in Drosophila.

Hunger elicits diverse, yet coordinated, adaptive responses across species, but the underlying signaling mechanism remains poorly understood. Here, we report on the function and mechanism of the Drosophila insulin-like system in the central regulation of different hunger-driven behaviors. We found that overexpression of Drosophila insulin-like peptides (DILPs) in the nervous system of fasted larvae suppressed the hunger-driven increase of ingestion rate and intake of nonpreferred foods (e.g., a less accessible solid food). Moreover, up-regulation of Drosophila p70/S6 kinase activity in DILP neurons led to attenuated hunger response by fasted larvae, whereas its down-regulation triggered fed larvae to display motivated foraging and feeding. Finally, we provide evidence that neural regulation of food preference but not ingestion rate may involve direct signaling by DILPs to neurons expressing neuropeptide F receptor 1, a receptor for neuropeptide Y-like neuropeptide F. Our study reveals a prominent role of neural Drosophila p70/S6 kinase in the modulation of hunger response by insulin-like and neuropeptide Y-like signaling pathways.

Adaptation, Physiological↗
PubMed2005

Prediction of glass transition temperatures of OLED materials using topological indices.

The QSPR study was performed between topological indices and glass transition temperatures (T(g)s) of organic light-emitting diode materials based on a diverse set of 80 compounds. A five-parameter correlation with the squared correlation coefficient R2 = 0.9304 and an average absolute error of 7.7 K was obtained through step-wise multi-linear regression analysis with leave-one-out cross-validation. The new model proposed is predictive and requires only topological indices in the calculations and has the advantage of the relative ease in calculating the descriptors, which makes it easier to apply. The predicted results of the new model are comparable to those of the existing equation by using the Comprehensives Descriptors for Structural and Statistical Analysis approach.

Glass↗
PubMed2005

Identification of potent type I MetAP inhibitors by simple bioisosteric replacement. Part 1: Synthesis and preliminary SAR studies of thiazole-4-carboxylic acid thiazol-2-ylamide derivatives.

A series of thiazole-4-carboxylic acid thiazol-2-ylamide (TCAT, 4) derivatives were designed and synthesized according to simple bioisosteric replacement from previously reported pyridine-2-carboxylic acid thiazol-2-ylamide (PCAT) MetAP inhibitors. The preliminary SAR studies demonstrated that these TCAT series of compounds showed different activity and selectivity compared with those of the corresponding PCAT compounds. These findings provide useful information for the design and discovery of more potent inhibitors of type I MetAPs.

Aminopeptidases↗
PubMed2005

The cell agglutination agent, phytohemagglutinin-L, improves the efficiency of somatic nuclear transfer cloning in cattle (Bos taurus).

One of the several factors that contribute to the low efficiency of mammalian somatic cloning is poor fusion between the small somatic donor cell and the large recipient oocyte. This study was designed to test phytohemagglutinin (PHA) agglutination activity on fusion rate, and subsequent developmental potential of cloned bovine embryos. The toxicity of PHA was established by examining its effects on the development of parthenogenetic bovine oocytes treated with different doses (Experiment 1), and for different durations (Experiment 2). The effective dose and duration of PHA treatment (150 microg/mL, 20 min incubation) was selected and used to compare membrane fusion efficiency and embryo development following somatic cell nuclear transfer (Experiment 3). Cloning with somatic donor fibroblasts versus cumulus cells was also compared, both with and without PHA treatment (150 microg/mL, 20 min). Fusion rate of nuclear donor fibroblasts, after phytohemagglutinin treatment, was increased from 33 to 61% (P < 0.05), and from 59 to 88% (P < 0.05) with cumulus cell nuclear donors. The nuclear transfer (NT) efficiency per oocyte used was improved following PHA treatment, for both fibroblast (13% versus 22%) as well as cumulus cells (17% versus 34%; P < 0.05). The cloned embryos, both with and without PHA treatment, were subjected to vitrification and embryo transfer testing, and resulted in similar survival (approximately 90% hatching) and pregnancy rates (17-25%). Three calves were born following vitrification and embryo transfer of these embryos; two from the PHA-treated group, and one from non-PHA control group. We concluded that PHA treatment significantly improved the fusion efficiency of somatic NT in cattle, and therefore, increased the development of cloned blastocysts. Furthermore, within a determined range of dose and duration, PHA had no detrimental effect on embryo survival post-vitrification, nor on pregnancy or calving rates following embryo transfer.

Animals↗
PubMed2005

Apical ammonium inhibition of cAMP-stimulated secretion in T84 cells is bicarbonate dependent.

Normal human colonic luminal (NH(4)(+)) concentration ([NH(4)(+)]) ranges from approximately 10 to 100 mM. However, the nature of the effects of NH(4)(+) on transport, as well as NH(4)(+) transport itself, in colonic epithelium is poorly understood. We elucidate here the effects of apical NH(4)(+) on cAMP-stimulated Cl(-) secretion in colonic T84 cells. In HEPES-buffered solutions, 10 mM apical NH(4)(+) had no significant effect on cAMP-stimulated current. In contrast, 10 mM apical NH(4)(+) reduced current within 5 min to 61 +/- 4% in the presence of 25 mM HCO(3)(-). Current inhibition was not simply due to an increase in extracellular K(+)-like cations, in that the current magnitude was 95 +/- 5% with 10 mM apical K(+) and 46 +/- 3% with 10 mM apical NH(4)(+) relative to that with 5 mM apical K(+). We previously demonstrated that inhibition of Cl(-) secretion by basolateral NH(4)(+) occurs in HCO(3)(-)-free conditions and exhibits anomalous mole fraction behavior. In contrast, apical NH(4)(+) inhibition of current in HCO(3)(-) buffer did not show anomalous mole fraction behavior and followed the absolute [NH(4)(+)] in K(+)-NH(4)(+) mixtures, where K(+) concentration + [NH(4)(+)] = 10 mM. The apical NH(4)(+) inhibitory effect was not prevented by 100 microM methazolamide, suggesting no role for apical carbonic anhydrase. However, apical NH(4)(+) inhibition of current was prevented by 10 min of pretreatment of the apical surface with 500 microM DIDS, 100 microM 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS), or 25 microM niflumic acid, suggesting a role for NH(4)(+) action through an apical anion exchanger. mRNA and protein for the apical anion exchangers SLC26A3 [downregulated in adenoma (DRA)] and SLC26A6 [putative anion transporter (PAT1)] were detected in T84 cells by RT-PCR and Northern and Western blots. DRA and PAT1 appear to associate with CFTR in the apical membrane. We conclude that the HCO(3)(-) dependence of apical NH(4)(+) inhibition of secretion is due to the action of NH(4)(+) on an apical anion exchanger.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗