Biomedical subjects

Paul Wong

Publications and source records attributed to Paul Wong.

At least 19 recordsLinked to original sources

PubMed2007

Gene expression profiling of early involuting mammary gland reveals novel genes potentially relevant to human breast cancer.

Mammary gland involution represents one of the most dramatic examples of programmed cell death/apoptosis and tissue regression during development, yet large gaps still exist in the understanding of the mechanisms involved, and the key factors that trigger involution, are not yet identified. With the focus on identifying "novel" genes associated with mammary gland regression, we used microarray analysis to examine differentially expressed genes during early mammary gland involution in the mouse. We then examined the relevance of candidate genes to human tumorigenesis and identified a number of genes not previously implicated or not well characterized in human breast cancer. The expression levels of these genes in human breast cancer were confirmed in breast cancer cell lines and breast tumor tissues. This pilot study demonstrates proof of principle that through the analysis of gene expression during mammary gland involution, it may be possible to identify "novel" genes relevant human breast cancer.

Animals↗

PubMed2006

Differential expression of claudin 1, 3, and 4 during normal mammary gland development in the mouse.

The claudins are a family of tight junction proteins that display varied tissue distribution and preferential specificity. We recently identified by microarray analysis, members of this family, particularly claudin 1 (cldn1), as highly upregulated genes in the mouse mammary gland during early involution. Gene expression was confirmed by immunohistochemistry and real-time PCR. We then examined gene and protein expression throughout normal mammary gland development. The cldn3 gene showed a steady increase in expression from pregnancy to involution, while cldn1 and cldn4 gene expression increased during pregnancy, but decreased sharply by D10 of lactation, and once again was significantly increased by D1 of involution (P < 0.001 for both genes). The different patterns of gene expression observed between cldn3, and cldn1, and 4 suggest that different family members may be functionally important at different times during mouse mammary gland development. All three genes exhibited a high level of expression at day 1 (D1) of involution, followed by a dramatic decrease in gene expression to day 10 of involution. Immunostaining with the cldn3 antibody showed intense staining of epithelial cells; however, a lesser degree of staining was evident with the cldn1 antibody. In addition to the lateral staining of epithelial cells, basal staining was evident at D1 and D2 of involution and cytoplasmic staining was evident during lactation. Since claudins are known to play a role as tight junction proteins, lateral and basal staining may suggest a role in other functions such as vesicle trafficking or remodeling of tight junctions at different stages of mammary gland development. Cldn1 and 3 antibodies also stained epithelial cells in mouse mammary tumors. In summary, cldn1, 3, and 4 are differentially expressed in the mammary gland during pregnancy, lactation, and involution, suggesting different roles for these proteins at different stages of mammary gland function. In addition, cldn1 and cldn3 are detected in mammary tumors and the wide distribution of cldn3 in particular, suggest specific roles for these proteins in mammary tumorigenesis.

Animals↗

PubMed2004

Expression of transthyretin and retinol binding protein mRNAs and secretion of transthyretin by cultured monkey retinal pigment epithelium.

PURPOSE: To document the expression of mRNA for transthyretin (TTR) and retinol binding protein (RBP) in native and cultured Rhesus monkey retinal pigmented epithelium (RPE); to compare mRNA transcripts for these two proteins expressed in RPE with those found in whole monkey liver and brain; to demonstrate the secretion of TTR by RPE during short-term maintenance in a protein-free, defined medium, as a manifestation of the differentiated state of these cells in vitro. METHODS: Total RNA was isolated from cultured RPE in first passage, after incubation for eight days in defined, protein-free medium. Conditioned medium was collected for western analysis at this time. Total RNA was also extracted from RPE/choroid freshly dissected from monkey eyes. Using cDNA probes for human TTR and RBP, northern analysis was performed on the total RNA from fresh and cultured RPE samples, together with poly(A+) mRNA purified from monkey liver and brain. RESULTS: Conditioned medium from RPE yielded TTR protein of the expected monomer subunit molecular size. The TTR secreted de novo from the cultured cells was detectable in the absence of biosynthetic labeling. With the exception of some extremely low abundance transcripts expressed in cultured RPE, all samples contained a single 900 bp transcript for TTR. Based on relative amounts of actual message, RPE ranks higher than liver in abundance of TTR mRNA. In contrast, both native monkey RPE and cultured RPE cells expressed comparatively low levels of mRNA for RBP. All samples displayed a single RBP mRNA transcript at 1100 bp. CONCLUSIONS: Our results indicate that TTR is a significant gene product of the RPE, and may be considered as a marker for a differentiated phenotype for these cells in culture. There is increased recognition of various forms of ocular pathology associated with mutations or other malfunctions involving TTR and RBP, warranting a greater understanding of mechanisms of transcriptional and translational control for these two proteins.

Animals↗

PubMed2004

Differentially expressed genes that encode potential markers of goldfish macrophage development in vitro.

Primary kidney macrophage (PKM) cultures derived from goldfish hematopoietic tissues develop from early progenitors to mature macrophages in response to endogenous growth factor(s). When grown in vitro, PKM shift from a proliferative phase, where most of the proliferation and differentiation events take place, to a senescence phase, where there is cessation of proliferation and differentiation events and ultimately cell death through a process of apoptosis. The phenotypic changes of PKM from the proliferative to senescence phase are a reflection of specific changes in gene expression; therefore, comparison of gene expression patterns between the two phases should lead to the identification of macrophage genes directly involved in the positive and negative regulation of hematopoietic events, as well as genes that are modulated downstream from these regulatory points. Differential cross-screening of the proliferative phase PKM cDNA library using proliferative and senescence phase (32)P-labeled cDNA probes identified several differentially expressed genes. Specifically, initial screen of 9200 clones yielded 734 differential primary clones that were isolated and analyzed using a PCR-based secondary screen. The majority of these clone isolates encoded a single transcript as determined by PCR amplification of the primary clones. The secondary screen confirmed the differential expression of 306 clones (3.32% of the total number of screened clones). Two hundred and forty four clones were sequenced; 158 and 86 were preferentially expressed during proliferative and senescence phases, respectively. Several potential candidates of fish macrophage hematopoiesis were identified. These include, for example, zinc finger protein 147, nucleophosmin, 14-3-3 protein, adenine nucleotide translocator 2 (ANT2), granulin, survivin-1, and apoptosis inhibitor-5. In addition, several potential markers of macrophage differentiation and/or function were identified and their expression patterns characterized across three distinct stages of macrophage development in vitro. These include legumain, CD63, interferon-inducible protein, macrosialin (CD68), transcription factor MafB, and the molecular chaperone BiP/GRP78. These analyses will facilitate future characterization of macrophage developmental events by providing a more global perspective of various facets of macrophage hematopoiesis.

Animals↗

PubMed2004

Pigment epithelium-derived factor in the monkey retinal pigment epithelium and interphotoreceptor matrix: apical secretion and distribution.

Pigment epithelium-derived factor (PEDF) is an extracellular protein derived from the retinal pigment epithelium (RPE), a tissue formed by polarized cells that release growth and trophic factors in a directional fashion. We have investigated the distribution and directional release of PEDF protein by the monkey RPE. We established primary cultures of monkey RPE cells that expressed the PEDF gene, and that synthesized and secreted the PEDF protein. Northern analysis of RPE cultures and monkey ocular tissues showed that PEDF transcripts were highly expressed in RPE as compared with several other monkey ocular tissues, being even more abundant in cultured cells than they were in the native RPE. The differentiated RPE cells in culture secreted protein that shared the immunological, biochemical and biological characteristics of PEDF. The overall PEDF levels in the RPE conditioned media reached 6.5 mg ml- after 8 days in culture (i.e. 1.1 pg of PEDF per RPE cell). RPE cells were cultivated on permeable supports as monolayers forming a barrier between apical and basal compartments. Apical and basal culture media were sampled at three or four-day intervals for 18 cycles, and the PEDF content was quantified. Most of the PEDF protein was significantly higher in the apical than in the basal medium (>4 times) at the initial recovery intervals, to be detected only in the apical medium at the latter intervals. In the native monkey eye, the concentration of soluble PEDF in the interphotoreceptor matrix (144 nM) was 7-fold and 25-fold greater than in vitreous and aqueous, respectively. PEDF was abundant in the interphotoreceptor matrix surrounding rod and cone outer segments, and was detectable at lower levels in the RPE as visualized by confocal microscopy. We concluded that PEDF synthesized by the RPE is secreted preferentially from the apical surface and is distributed apically to the RPE bordering the outer segments of photoreceptors. PEDF can be a useful marker for RPE polarization and differentiation. The polarization of RPE may be an important mechanism to control PEDF secretion and our results offer interesting possibilities on regulation of PEDF.

Animals↗

PubMed2004

Expression of neurturin, glial cell line-derived neurotrophic factor, and their receptor components in light-induced retinal degeneration.

PURPOSE: Dysregulation of neurturin (NTN) expression has been linked to photoreceptor apoptosis in a mouse model of inherited retinal degeneration. To investigate the extent to which any such dysregulation depends on the nature of the apoptotic trigger, the expression of NTN, glial cell line-derived neurotrophic factor (GDNF), and their corresponding receptor components were compared in a rat model of light-induced retinal degeneration. METHODS: Retinal expression of NTN, GDNF, their corresponding receptors GFRalpha-2 and -1, the transmembrane receptor tyrosine kinase (Ret), and cSrc-p60, a member of the cytoplasmic protein-tyrosine kinases family, were analyzed by Western blot analysis and immunocytochemistry in cyclic light- and dark-reared rats in the presence and absence of intense light exposure. RESULTS: All components for NTN-mediated signaling activation are present in rat photoreceptors and retinal pigment epithelium, the cells primarily affected by light-induced damage. The expression levels of GDNF, its receptor components, and NTN, were not affected by light-induced stress. However, GFRalpha-2 expression strikingly increased with the extent of retinal damage, especially at the photoreceptors, in contrast to decreased levels that were observed previously in an inherited degeneration model. CONCLUSIONS: The present study indicates that the expression of receptors of the GDNF family is independently regulated in normal and light-damaged rat retina, and in conjunction with previous work, suggests that the pattern of modulation of these genes during photoreceptor degeneration is determined by the nature of the apoptotic trigger. Such differential responses to different modes of retinal degeneration may reflect influences of the neurotrophic system on photoreceptor survival or in the regulation of neuronal plasticity.

Animals↗

PubMed2004

Coordinated changes in classes of ribosomal protein gene expression is associated with light-induced retinal degeneration.

PURPOSE: To identify genes with altered expression levels in the degenerating retina in a light-induced retinal degeneration (LIRD) model. METHODS: Adult Sprague-Dawley rats were exposed to intense green light for 4 hours. After this treatment, the retinas were excised, RNA was extracted, and a cDNA library was prepared. The cDNA library was differentially cross-screened with probes representing 0-hour and 4-hour light-exposed rat retina. Transcripts with altered expression levels were sequenced and expression was confirmed by Northern blot analysis. Gene-specific primers were designed and used to examine the expression levels of other genes involved in protein synthesis. Promoter sequences of the ribosomal-binding protein (Rbp) genes were analyzed for transcription-binding sites. RESULTS: Of the 10,000 clones that were initially screened, 41 exhibited altered expression levels. Six of these corresponded to five known Rbp genes. Six additional Rbp genes were also examined. In total, 9 of 11 Rbp genes exhibited an increase in expression levels in response to a 4-hour light exposure. In contrast, the transcript levels of elongation factor 1alpha1 and 18S rRNA did not increase. The most abundant transcription factor-binding sites conserved in the promoter regions of all Rbp genes examined in this study include AP-1, Oct-1, V-myb, USF, Pax-4, and the FOX family of transcription factors. CONCLUSIONS: The results indicate that light-induced retinal degeneration (LIRD) is associated with increased expression of specific Rbp genes. These Rbp genes may be involved in mediating visual cell loss in LIRD through a translational or an extraribosomal mechanism.

Animals↗

PubMed2003

Design, synthesis, and structure-activity relationships of substituted piperazinone-based transition state factor Xa inhibitors.

The structure-activity relationship of a novel series of substituted piperazinone-based factor Xa inhibitors is described. The most potent compound 34 displays IC(50) of 0.9 nM.

Anticoagulants↗

PubMed2003

Design, synthesis and structure-activity relationships of benzoxazinone-based factor Xa inhibitors.

A series of benzoxazinone derivatives was designed and synthesized as factor Xa inhibitors. We demonstrated that the naphthyl moiety in the aniline-based compounds 1 and 2 can be replaced with benzene-fused heterobicycles and biaryls to give factor Xa inhibitors with improved trypsin selectivity. The P4 modifications lead to monoamidines which are moderately active. The benzoxazinones 41-45 are potent against factor Xa, retain the improved trypsin selectivity of the corresponding aniline-based compounds, and show strong antithrombotic effect dose responsively.

Aniline Compounds↗

PubMed2003

Design and synthesis of factor Xa inhibitors and their prodrugs.

In addition to our previously reported fluoro acrylamides Xa inhibitors 2 and 3, a series of potent and novel cyclic diimide amidine compounds has been identified. In efforts to improve their oral bioavailability, replacement of the amidine group with methyl amidrazone gives compounds of moderate potency (14, IC(50)=0.028 microM). In the amidoxime prodrug approach, the amidoxime compounds show good oral bioavailability in rats and dogs. High plasma level of prodrug 26 and significant concentration of active drug 26a were obtained upon oral administration of prodrug 26 in rats.

Amidines↗

PubMed2002

Substituted acrylamides as factor Xa inhibitors: improving bioavailability by P1 modification.

To overcome the low bioavailability of our substituted acrylamide P1 benzamidine factor Xa inhibitors reported previously, neutral and less basic groups were used to replace the benzamidine. As a result, a series of P1 aminoisoquinoline substituted acrylamide Xa inhibitors was identified to be potent, selective, and orally bioavailable. Modification of P4 moiety of these compounds further improved their pharmacokinetic properties.

Acrylamides↗

PubMed2002

Design, synthesis, and SAR of monobenzamidines and aminoisoquinolines as factor Xa inhibitors.

Monoamidine FXa inhibitors 3 were designed and synthesized. SAR studies and molecular modeling led to the design of conformationally constrained diaryl ethers 4 and 5, as well as benzopyrrolidinone 7 as potent FXa inhibitors. The monoamidines show high efficacy in a DVT model, but lack desirable oral bioavailability. The benzopyrrolidinone-based aminoisoquinolines 8 do not show significant improvement in oral bioavailability.

Administration, Oral↗

PubMed2002

Design, synthesis and biological activity of novel non-amidine factor Xa inhibitors. Part 1: P(1) structure-activity relationships of the substituted 1-(2-Naphthyl)-1H-pyrazole-5-carboxylamides.

Based on DuPont Pharmaceuticals' monobenzamidine lead structure SN429, we have designed the biphenyl 1-(2-naphthyl)-1H-pyrazole-5-carboxylamides as a novel series of non-basic factor Xa inhibitors. We have discovered that the displacement of the benzamidine moiety with substituted 2-naphthyl structures not only results in highly potent factor Xa inhibitors, but also significantly increases their enzyme specificity and oral bioavailability.

Amides↗

PubMed2002

Design, synthesis, and SAR of substituted acrylamides as factor Xa inhibitors.

Substituted acrylamides were used as templates that bridge P1 and P4 binding elements, resulting in a series of potent (sub-nanomolar) and selective factor Xa inhibitors. In this template, cis-geometry of P1 and P4 ligands is highly preferred. SAR on the substituting groups, as well as on modification of P1 and P4 moieties is described. Compounds in this series show good in vivo efficacy in animal models.

Acrylamides↗

PubMed2002

Identification and characterization of genes differentially expressed in the testis/vas deferens of the fed male tick, Amblyomma hebraeum.

Most ixodid ticks must feed for at least a few days to complete gonad maturation. Substances produced by the mature male gonad, and carried in the spermatophore, induce physiological changes in the female that lead to engorgement and oviposition. To begin defining the molecular phenotype at this stage of male development, we differentially cross-screened a cDNA library made from the testis and vas deferens of fed ticks (Amblyomma hebraeum Koch) and isolated 35 genes that were putatively up-regulated in tissues of fed compared to unfed animals. While the majority of these were novel, two clones, AhT/VD16 and AhT/VD146, yielded homologies (53 and 44%) to known genes (acylphosphatse and 9.0 kD Drosophila melanogaster basic protein, respectively). Results of Northern blot analysis of AhT/VD16 and AhT/VD146 demonstrate that both clones hybridized with mRNA transcripts that were up-regulated in the testis/vas deferens of fed compared to unfed males. In addition, hybridization of clone AhT/VD16 to water strider (Gerris argentatus) genomic DNA, and sequence similarities to mammalian acylphosphatase, suggest that it represents an evolutionarily conserved sequence.

Acid Anhydride Hydrolases↗

PubMed2002

Don't throw away the ring: indications and use.

Protective rings are a valuable adjunct in revision acetabular surgery. Two types of rings are used. The roof ring, which is the smaller of the 2 rings, provides support from the ilium to the inferomedial part of the acetabulum. The reconstructive ring or cage provides support from the ilium to the ischium. Both devices can be used to protect morcellized or structural bone-graft. The roof ring can be used with morcellized graft if the ring can make contact with host-bone at the superior and inferomedial aspect of the acetabulum. If the defect is more global but still contained so that the entire acetabulum is filled with morcellized bone, the larger reconstructive ring should be used. Small structural grafts that support <50% of the cup may be protected by a roof ring. Larger structural grafts that support >50% of the cup should be protected by a reconstructive ring.

Arthroplasty, Replacement, Hip↗

PubMed2002

Protective effect of fleroxacin against the nephrotoxicity of isepamicin in rats.

The protective effect of fleroxacin on isepamicin-induced nephrotoxicity was investigated. Wistar rats were administered either fleroxacin 100 mg/kg orally, isepamicin 300 mg/kg subcutaneously, or fleroxacin and isepamicin in combination for 14 d. The animals given 300 mg/kg of isepamicin showed a significant increase in urine N-acetyl-beta-D-glucosaminidase (NAG) levels as compared with the control animals which received saline (p<0.01). However, the increase in NAG level was markedly less when isepamicin was administered in combination with fleroxacin (p<0.01). Fleroxacin alone had no effect on urine NAG activity. Serum creatinine and blood urea nitrogen (BUN) levels were significantly higher in animals treated with isepamicin alone than in the control animals (p<0.01) or animals receiving the isepamicin fleroxacin combination (p<0.01). Histopathologically, fleroxacin induced very few cellular alterations, but considerably reduced the manifestation of typical signs of isepamicin nephrotoxicity. This investigation demonstrates that fleroxacin protects animals against isepamicin-induced nephrotoxicity.

Acetylglucosaminidase↗

PubMed2002

Acetabular revision using grafts and cages.

Principles of acetabular revision include stable bone coverage that can support the new acetabular component, restoration of the anatomy and bone stock for future revisions, and equalization of leg length. Achieving these goals depends on the severity of the pelvic defect. Classification of these acetabular defects is critical to optimal treatment choice. A classification formulated by the authors of this paper and based on proven Severity Instrument methodology has been applied effectively at their institutions after meeting reliability and validation criteria. Approaches to acetabular revision based on this classification have resulted in good outcomes.

Acetabulum↗