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Jie Hu

Publications and source records attributed to Jie Hu.

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

Potential difference measurements of ocular surface Na+ absorption analyzed using an electrokinetic model.

PURPOSE: Corneal and conjunctival epithelia are capable of transcellular Na+ absorption and Cl- secretion, which drives water movement across these tissues. A recent study demonstrated with a new open-circuit potential difference (PD) technique that Cl- moves across the ocular surface in mice through Ca2+- and cAMP-sensitive Cl- channels, the latter pathway being the cystic fibrosis (CF) transmembrane conductance regulator (CFTR). The purpose of the present study was to identify transporting mechanisms involved in Na+ absorption and to develop a mathematical model of ocular surface ion transport to quantify the relative magnitudes of and electrochemical coupling among transporting processes. METHODS: PDs across the fluid-bathed ocular surface were measured in anesthetized wild-type and CF mice in response to Na+, Cl-, and K+ ion substitution and transporter agonists, inhibitors, and substrates. An electrokinetic model of the ocular surface epithelium was developed to simulate PD measurements, which involved computation of membrane potentials and cell [Na+], [K+], [Cl-] and volume from transporter activities and extracellular ion concentrations. RESULTS: Na+ replacement produced a 6 +/- 2-mV depolarization that was blocked by amiloride (K(i) 0.8 microM) and benzamil (Ki 0.2 microM). The Na+-dependent depolarization by amiloride was significantly greater in CF mice (19 +/- 3 mV). In wild-type mice, D-, but not L-glucose produced a phloridzin-sensitive, 4.1-mV hyperpolarization in the presence of Na+ and amiloride, with a Km for D-glucose of 2.5 mM. Glycine and L-arginine also produced Na+-dependent hyperpolarizations. The epithelial transport model accurately reproduced experimental PD measurements. CONCLUSIONS: PD measurements coupled with model computations defined quantitatively the roles of Na+ and Cl- transport processes in ocular surface ion and fluid secretion, and indicated that CFTR-dependent changes in apparent epithelial Na+ channel (ENaC) activity could be accounted for by electrochemical coupling, without requiring ENaC-CFTR interactions. The data and modeling also predicted significant enhancement of ocular surface fluid secretion by ENaC inhibitors and CFTR activators as possible therapies for dry eye syndromes.

Absorption↗
PubMed2006

Application of multicolor banding for identification of complex chromosome 18 rearrangements.

Multicolor chromosome banding (mBAND) is a recently developed technique that allows the delineation of chromosomal regions with a resolution of a few megabase pairs. The resolution of mBAND is slightly below that of conventional chromosome banding; however, the color bands have a great value in identifying chromosomal abnormalities, particularly complex chromosome rearrangements, and intrachromosome exchanges (ie, inversions, deletions, duplications, and insertions). These abnormalities cannot be defined easily by conventional cytogenetic analysis or chromosome paint. In this report, we present the application of the mBAND analysis for identification of complex intrachromosome rearrangements of chromosome 18 in a child with dysmorphic features.

Chromosome Aberrations↗
PubMed2005

Luminally active, nonabsorbable CFTR inhibitors as potential therapy to reduce intestinal fluid loss in cholera.

Enterotoxin-mediated secretory diarrheas such as cholera involve chloride secretion by enterocytes into the intestinal lumen by the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. We previously identified glycine hydrazide CFTR blockers that by electrophysiological studies appeared to block the CFTR anion pore at its lumen-facing surface. Here, we synthesize highly water-soluble, nonabsorbable malondihydrazides by coupling 2,4-disulfobenzaldehyde, 4-sulfophenylisothiocyante, and polyethylene glycol (PEG) moieties to 2-naphthalenylamino-[(3,5-dibromo-2,4-dihydroxyphenyl) methylene] propanedioic acid dihydrazide, and aminoacethydrazides by coupling PEG to [(N-2-naphthalenyl)-2-(2-hydroxyethyl)]-glycine-2-[(3,5-dibromo-2,4-dihydroxyphenyl) methylene] hydrazide. Compounds rapidly, fully and reversibly blocked CFTR-mediated chloride current with Ki of 2-8 microM when added to the apical surface of epithelial cell monolayers. Compounds did not pass across Caco-2 monolayers, and were absorbed by <2%/hr in mouse intestine. Luminally added compounds blocked by >90% cholera toxin-induced fluid secretion in mouse intestinal loops, without inhibiting intestinal fluid absorption. These orally administered, nonabsorbable, nontoxic CFTR inhibitors may reduce intestinal fluid losses in cholera.

Animals↗
PubMed2005

Correlation quantum dynamics between an electron and D+2 molecule with attosecond resolution.

Recently, Niikura et al. [Nature (London) 421, 826 (2003)] have applied the entanglement approach to exploit the correlation between the electronic and nuclear wave packets. Here, we use the time-dependent-wave-packet method to calculate the kinetic energy distribution of the D+ ion resulting from the recollision between an electron and its parent ion D+2(X2Sigma+g) within the attoseconds time scale. Our theoretical results of the D+ ion kinetic energy spectra accord well with the experimental ones, and the recollision probabilities between the electron and the D+2 molecule have been calculated.

Journal Article↗
PubMed2005

Silencing the epidermal growth factor receptor gene with RNAi may be developed as a potential therapy for non small cell lung cancer.

Lung cancer has emerged as a leading cause of cancer death in the world. Non-small cell lung cancer (NSCLC) accounts for 75-80% of all lung cancers. Current therapies are ineffective, thus new approaches are needed to improve the therapeutic ratio. Double stranded RNA (dsRNA)-mediated RNA interference (RNAi) has shown promise in gene silencing, the potential of which in developing new methods for the therapy of NSCLC needs to be tested. We report here RNAi induced effective silencing of the epidermal growth factor receptor (EGFR) gene, which is over expressed in NSCLC. NSCLC cell lines A549 and SPC-A1 were transfected with sequence- specific dsRNA as well as various controls. Immune fluorescent labeling and flow cytometry were used to monitor the reduction in the production of EGFR protein. Quantitative reverse-transcriptase PCR was used to detect the level of EGFR mRNA. Cell count, colony assay, scratch assay, MTT assay in vitro and tumor growth assay in athymic nude mice in vivo were used to assess the functional effects of EGFR silencing on tumor cell growth and proliferation. Our data showed transfection of NSCLC cells with dsRNA resulted in sequence specific silencing of EGFR with 71.31% and 71.78 % decreases in EGFR protein production and 37.04% and 54.92% in mRNA transcription in A549 and SPC-A1 cells respectively. The decrease in EGFR protein production caused significant growth inhibition, i.e.: reducing the total cell numbers by 85.0% and 78.3%, and colony forming numbers by 63.3% and 66.8%. These effects greatly retarded the migration of NSCLC cells by more than 80% both at 24 h and at 48 h, and enhanced chemo-sensitivity to cisplatin by four-fold in A549 cells and seven-fold in SPC-A1. Furthermore, dsRNA specific for EGFR inhibited tumor growth in vivo both in size by 75.06% and in weight by 73.08%. Our data demonstrate a new therapeutic effect of sequence specific suppression of EGFR gene expression by RNAi, enabling inhibition of tumor proliferation and growth. However, in vivo use of dsRNA for gene transfer to tumor cells would be limited because dsRNA would be quickly degraded once delivered in vivo. We thus tested a new bovine lentiviral vector and showed lentivector-mediated RNAi effects were efficient and specific. Combining RNAi with this gene delivery system may enable us to develop RNAi for silencing EGFR into an effective therapy for NSCLC.

Journal Article↗
PubMed2005

[Homologous dermal acellular matrix graft for urethral reconstruction in man (report of 16 cases)].

OBJECTIVE: To investigated the value of homologous dermal acellular matrix graft (AMG) for urethral reconstruction in man, and found an ideal replacement material to simplify the urethroplastic surgery. METHODS: 16 male patients, aged 18-46 (mean 26.5), with urethral diseases were treated with allograft of tissue engineering material AMG. The causes of urethroplasty were complex urethral stricture followed by pelvic fracture (13 cases), anterior urethral stricture (2 cases), hypospadia (1 case). During the operation, AMG was sutured to a tubular graft and replaced the defect urethra. A 18-22 Fr silicone catheter was inserted in the reconstructed urethra for 4-6 weeks. RESULTS: All 16 patients were voiding well after removing the catheter, urethrography reveal excellent caliber of the reconstructed urethra. Urethroscopic examination showed the graft urethra was covered by epithelial tissue and grew into the native tissue. But stenosis was developed in 3 patients postoperatively, 1 patients received transurethral incision, another 2 needed urethral sounding. The patients were followed-up for 12-72 months (mean 45.6), no rejection was observed, all patients voided normally except 4 cases needed urethral dilatation periodically. CONCLUSION: The homologous dermal acellular matrix graft may serve as an ideal replacement material for complex urethral stricture or defect, without concern of rejection.

Adolescent↗
PubMed2005

Phenylglycine and sulfonamide correctors of defective delta F508 and G551D cystic fibrosis transmembrane conductance regulator chloride-channel gating.

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel cause cystic fibrosis. The delta F508 mutation produces defects in channel gating and cellular processing, whereas the G551D mutation produces primarily a gating defect. To identify correctors of gating, 50,000 diverse small molecules were screened at 2.5 microM (with forskolin, 20 microM) by an iodide uptake assay in epithelial cells coexpressing delta F508-CFTR and a fluorescent halide indicator (yellow fluorescent protein-H148Q/I152L) after delta F508-CFTR rescue by 24-h culture at 27 degrees C. Secondary analysis and testing of >1000 structural analogs yielded two novel classes of correctors of defective delta F508-CFTR gating ("potentiators") with nanomolar potency that were active in human delta F508 and G551D cells. The most potent compound of the phenylglycine class, 2-[(2-1H-indol-3-yl-acetyl)-methylamino]-N-(4-isopropylphenyl)-2-phenylacetamide, reversibly activated delta F508-CFTR in the presence of forskolin with K(a) approximately 70 nM and also activated the CFTR gating mutants G551D and G1349D with K(a) values of approximately 1100 and 40 nM, respectively. The most potent sulfonamide, 6-(ethylphenylsulfamoyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid cycloheptylamide, had K(a) approximately 20 nM for activation of delta F508-CFTR. In cell-attached patch-clamp experiments, phenylglycine-01 (PG-01) and sulfonamide-01 (SF-01) increased channel open probability >5-fold by the reduction of interburst closed time. An interesting property of these compounds was their ability to act in synergy with cAMP agonists. Microsome metabolism studies and rat pharmacokinetic analysis suggested significantly more rapid metabolism of PG-01 than SF-03. Phenylglycine and sulfonamide compounds may be useful for monotherapy of cystic fibrosis caused by gating mutants and possibly for a subset of delta F508 subjects with significant delta F508-CFTR plasma-membrane expression.

Animals↗
PubMed2005

Ruthenium(III) chloride catalyzed oxidation of pyrene and 2,7-disubstitued pyrenes: an efficient, one-step synthesis of pyrene-4,5-diones and pyrene-4,5,9,10-tetraones.

Pyrene and 2,7-disubstituted pyrenes have been oxidized with ruthenium(III) chloride (RuCl3) and sodium periodate (NaIO4) under very mild conditions to 4,5-diones or 4,5,9,10-tetraones. Thus, the oxidation has been controlled by varying the amount of oxidant and reaction temperature to proceed exclusively at the pyrene 4- and 5-positions or at the 4-, 5-, 9-, and 10-positions.

Journal Article↗
PubMed2005

A case of myelodysplastic syndrome with acquired monosomy 7 in a child with a constitutional t(1;19) and a mosaicism for trisomy 21.

A 3-year-old patient presented with anemia, thrombocytopenia, and blasts in the peripheral blood. A bone marrow aspirate revealed a myelodysplastic syndrome (MDS). A mosaic abnormal female karyotype 46,XX, t(1;19)(q42; p13.1)c[12]/ 47,idem,+21c[3]/ 47,idem,-7,+21c,+mar[7] was obtained on G-banded metaphases from unstimulated bone marrow aspirate cell culture. To rule out constitutional abnormalities, we performed a cytogenetic analysis on the patient's phytohemagglutinin-stimulated peripheral blood and cultured skin fibroblasts. A karyotype of 46,XX,t(1;19) (q42;p13.1)c was found in all 20 peripheral lymphocytes analyzed, confirming the constitutional origin of the translocation. In addition, 5 out of 50 cells from two separate cultures of the skin fibroblasts contained an extra chromosome 21. The presence of two cell lines in multiple cultures indicates that the patient is a true low-level mosaic for trisomy 21. Because of the finding of monosomy 7 and a marker chromosome only in the trisomy 21 clone, we conclude that the leukemic clone arose from a hematopoietic precursor with constitutional trisomy 21. It is also possible that the t(1;19) played some role in the development of the MDS. Because acute myelogenous leukemia (AML) and MDS with Down syndrome (DS) have distinct biologic and clinical features, the identification of DS patients with a mild or normal phenotype in the AML/MDS population is of fundamental importance for clinical diagnosis and management.

Child, Preschool↗
PubMed2005

Loss of DNA copy number of 10q is associated with aggressive behavior of leiomyosarcomas: a comparative genomic hybridization study.

Leiomyosarcomas (LMS) account for 10-20% of all soft tissue sarcomas. We analyzed 10 primary, 5 metastatic, and 2 recurrent extrauterine LMS. Genomic imbalances were detected in 15 out of the 17 tumors. The most common regions of loss were 13q (59%, 10 of 17), 10q (59%, 10 of 17), 2q (35%, 6 of 17), and 16q (29%, 5 of 17). The most common region of gain was 5p (35%, 6 of 17). High-level gain of DNA copy number was detected in 6p and 17p. Loss of function of tumor suppressor genes or the activation of oncogenes (or both of these factors) resulting from these copy number changes might play an important role in the development of extrauterine LMS. Large tumors and tumors with metastasis showed 10q deletions. Gain of 5p was detected only in G3 tumors. These findings are consistent with our earlier study on uterine LMS and indicate that loss of 10q and gain of 5p are associated with an aggressive behavior of LMS. A larger series of cases is needed to confirm these results.

Adult↗
PubMed2004

Developmental expression and function of Bmp4 in spermatogenesis and in maintaining epididymal integrity.

Bone morphogenetic proteins (BMPs) play essential roles in many aspects of developmental biology. We have previously shown that Bmp7, Bmp8a, and Bmp8b of the 60A class of Bmp genes have additive effects in spermatogenesis and in maintaining the epididymal integrity of the caput and caudal regions. Here we report that Bmp4 of the Dpp class has a unique expression pattern in the developing testis and epididymis. Bmp4 heterozygous males on a largely C57BL/6 background show compromised fertility due to degeneration of germ cells, reduced sperm counts, and decreased sperm motility. More interestingly, some of these males show extensive degeneration of the epididymal epithelium in the corpus region, rather than in the caput and cauda regions as for Bmp7 and Bmp8 mutants. Thus, these genetic data reveal a region-specific requirement of different classes of BMPs for epididymal epithelium to survive and have significant implications on male reproductive health and perhaps birth control.

Animals↗
PubMed2004

BMP4 supports self-renewal of embryonic stem cells by inhibiting mitogen-activated protein kinase pathways.

The fate of pluripotent stem cells is tightly controlled during early embryonic development. Both the derivation and the maintenance of embryonic stem cells (ES cells) in vitro depend on feeder cell-derived growth factors that are largely unidentified. To dissect the mechanisms governing pluripotency, we conducted a screen to identify factors that are produced by mouse embryonic fibroblast STO cells and are required to maintain the pluripotency of ES cells. One of the factors is bone morphogenetic protein 4 (BMP4). Unexpectedly, the major effect of BMP4 on the self-renewal of ES cells is accomplished by means of the inhibition of both extracellular receptor kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) pathways, and inhibitors of ERK and p38 MAPKs mimic the effect of BMP4 on ES cells. Importantly, inhibition of the p38 MAPK pathway by SB203580 overcomes the block in deriving ES cells from blastocysts lacking a functional Alk3, the BMP type IA receptor. These results uncover a paradigm for BMP signaling in the biology of pluripotent stem cells.

Animals↗
PubMed2004

Use of chemically modified PMMA microspheres for enzyme immobilization.

Modified poly(methyl methacrylate) (PMMA) microspheres, about 7microm in diameter, carrying aldehyde groups on their surfaces were synthesized and used as the support for enzyme immobilization. The immobilizing behavior as well as the properties of immobilized enzyme was studied. The amount of bound enzyme can be extended to 76.8mg g(-1) support, which is relatively much higher than other supports. The kinetic investigation derived from three typical models shows that the practical process is more complicated than the ideal condition, with one or more interactions being involved in the immobilization process. The K(m) value is actually larger and V(max) is smaller in the immobilized form than those in the free form. The increased resistance of the immobilized enzyme against the changes of temperature indicates that immobilizing enzyme onto the modified microspheres is useful for enzyme immobilization.

Adsorption↗
PubMed2004

Technological advances in high-throughput screening.

High-throughput screening (HTS) is the process of testing a large number of diverse chemical structures against disease targets to identify 'hits'. Compared to traditional drug screening methods, HTS is characterized by its simplicity, rapidness, low cost, and high efficiency, taking the ligand-target interactions as the principle, as well as leading to a higher information harvest. As a multidisciplinary field, HTS involves an automated operation-platform, highly sensitive testing system, specific screening model (in vitro), an abundant components library, and a data acquisition and processing system. Various technologies, especially the novel technologies such as fluorescence, nuclear-magnetic resonance, affinity chromatography, surface plasmon resonance, and DNA microarray, are now available, and the screening of more than 100,000 samples per day is already possible. Fluorescence-based assays include the scintillation proximity assay, time-resolved energy transfer, fluorescence anisotropy, fluorescence correlation spectroscopy, and fluorescence fluctuation spectroscopy. Fluorescence-based techniques are likely to be among the most important detection approaches used for HTS due to their high sensitivity and amenability to automation, giving the industry-wide drive to simplify, miniaturize, and speed up assays. The application of NMR technology to HTS is another recent trend in drug research. One advantage afforded by NMR technology is that it can provide direct information on the affinity of the screening compounds and the binding location of protein. The structure-activity relationship acquired from NMR analysis can sharpen the library design, which will be very important in furnishing HTS with well-defined drug candidates. Affinity chromatography used for library screening will provide the information on the fundamental processes of drug action, such as absorption, distribution, excretion, and receptor activation; also the eluting curve can give directly the possibility of candidate drug. SPR can measure the quantity of a complex formed between two molecules in real-time without the need for fluorescent or radioisotopic labels. SPR is capable of characterizing unmodified biopharmaceuticals, studying the interaction of drug candidates with macromolecular targets, and identifying binding partners during ligand fishing experiments. DNA microarrays can be used in HTS be used to further investigate the expression of biological targets associated with human disease, which then opens new and exciting opportunities for drug discovery. Without doubt, the addition of new technologies will further increase the application of HTS in drug screening and its related fields.

Animals↗
PubMed2003

Role of aquaporin and sodium channel in pleural water movement.

The role of the ENaC sodium channel and aquaporin-1 (AQP1) water channel on pleural fluid dynamics in mice was investigated. 0.25 ml of hypertonic or isosmolar fluid was infused into the pleural space in anesthetized wildtype and AQP1 null mice. Pleural fluid was sampled at specified times to quantify the osmolality and volume. The sodium channel activator terbutaline increased isosmolar fluid clearance by 90% while the sodium channel inhibitor amiloride decreased it by 15%, but had no effect on osmotically driven water transport. AQP1 deletion significantly decreased osmotic water transport in pleural space by twofold, but it had no effect on isosmolar fluid clearance. Pretreatment with dexamethasone increased pleural osmotic fluid entry by 25%, while intravenous injection of HgCl2 decreased osmotic pleural water movement by 43%. These results provided evidence for a role of a sodium channel in pleural fluid absorption; AQP1 plays a major role in osmotic liquid transport but it does not affect isosmolar fluid clearance.

Amiloride↗
PubMed2003

Establishment of a nude mouse model of hepatic metastasis for evaluation of targeted retroviral gene delivery.

BACKGROUND AND OBJECTIVES: The goal of this study was to establish a reproducible nude mouse model of liver metastasis and investigate the potential of deploying targeted injectable retroviral vectors for metastatic gastrointestinal cancer. METHODS: Human cancer cells were injected into the portal vein via an indwelling catheter. The animals were sacrificed at specified time intervals, and the number of tumor nodules was counted in histologic sections of harvested livers. A group of animals received either an extracellular matrix-targeted or a nontargeted retroviral vector bearing a beta-galactosidase gene by portal vein infusion. RESULTS: The number of tumor nodules increased progressively over time at </=50 days post-infusion (r = 0.81; P < 0.0001). Transduction of tumor nodules was observed in the animals that received a matrix-targeted, but not a nontargeted, vector. CONCLUSIONS: We have established a reproducible nude mouse model of liver metastasis, and demonstrated the feasibility of gene delivery to metastatic tumor nodules in vivo by portal vein infusions of a matrix-targeted retroviral vector.

Animals↗