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Biomedical subjects

J S Welch

Publications and source records attributed to J S Welch.

At least 19 recordsLinked to original sources
PubMed2000

15-deoxy-delta 12,14-prostaglandin J2 inhibits multiple steps in the NF-kappa B signaling pathway.

Prostaglandin J(2) (PGJ(2)) and its metabolites Delta(12)-PGJ(2) and 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) are naturally occurring derivatives of prostaglandin D(2) that have been suggested to exert antiinflammatory effects in vivo. 15d-PGJ(2) is a high-affinity ligand for the peroxisome proliferator-activated receptor gamma (PPARgamma) and has been demonstrated to inhibit the induction of inflammatory response genes, including inducible NO synthase and tumor necrosis factor alpha, in a PPARgamma-dependent manner. We report here that 15d-PGJ(2) potently inhibits NF-kappaB-dependent transcription by two additional PPARgamma-independent mechanisms. Several lines of evidence suggest that 15d-PGJ(2) directly inhibits NF-kappaB-dependent gene expression through covalent modifications of critical cysteine residues in IkappaB kinase and the DNA-binding domains of NF-kappaB subunits. These mechanisms act in combination to inhibit transactivation of the NF-kappaB target gene cyclooxygenase 2. Direct inhibition of NF-kappaB signaling by 15d-PGJ(2) may contribute to negative regulation of prostaglandin biosynthesis and inflammation, suggesting additional approaches to the development of antiinflammatory drugs.

Animals↗
PubMed2000

Regulation of macrophage gene expression by the peroxisome proliferator-activated receptor-gamma.

The peroxisome proliferator-activated receptor-gamma (PPAR-gamma), which is a member of the nuclear hormone receptor superfamily and was originally shown to play an important role in adipocyte differentiation and glucose homeostasis, is now known to regulate cellular proliferation and inflammatory responses. A range of synthetic and naturally occurring substances activates PPAR-gamma, however the identities of endogenous ligands for PPAR-gamma and their means of production in vivo have not been well established. In monocytes and macrophages, interleukin-4 (IL-4) increases the expression of 12/15-lipoxygenase and thus 13-HODE and 15-HETE production. We show that IL-4 induces the expression of PPAR-gamma and provide evidence that the coordinate induction of PPAR-gamma and 12/15-lipoxygenase mediates IL-4 dependent transcription of the CD36 gene and down-regulation of iNOS in macrophages. These findings suggest that PPAR-gamma activity may play an important role in mediating macrophage gene expression signaled by IL-4.

Animals↗
PubMed1999

Interleukin-4-dependent production of PPAR-gamma ligands in macrophages by 12/15-lipoxygenase.

The peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a ligand-dependent nuclear receptor that has been implicated in the modulation of critical aspects of development and homeostasis, including adipocyte differentiation, glucose metabolism and macrophage development and function. PPAR-gamma is activated by a range of synthetic and naturally occurring substances, including antidiabetic thiazolidinediones, polyunsaturated fatty acids, 15-deoxy-delta prostaglandin J2 and components of oxidized low-density lipoprotein, such as 13-hydroxyoctadecadienoic acid (13-HODE) and 15-hydroxyeicosatetraenoic acid (15-HETE). However, the identities of endogenous ligands for PPAR-gamma and their means of production in vivo have not been established. In monocytes and macrophages, 13-HODE and 15-HETE can be generated from linoleic and arachidonic acids, respectively, by a 12/15-lipoxygenase that is upregulated by the TH2-derived cytokine interleukin-4. Here we show that interleukin-4 also induces the expression of PPAR-gamma and provide evidence that the coordinate induction of PPAR-gamma and 12/15-lipoxygenase mediates interleukin-4-dependent transcription of the CD36 gene in macrophages. These findings reveal a physiological role of 12/15-lipoxygenase in the generation of endogenous ligands for PPAR-gamma, and suggest a paradigm for the regulation of nuclear receptor function by cytokines.

Animals↗
PubMed1999

The peroxisome proliferator-activated receptor(PPARgamma) as a regulator of monocyte/macrophage function.

Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors of the nuclear hormone receptor super-family, which includes the steroid, retinoid, and thyroid hormone receptors. The PPARs can be activated by fatty acids and their eicosanoid metabolites, and have until recently been considered primarily to regulate genes involved in glucose and lipid homeostasis. In the past year there has been an explosive increase in research implicating PPARgamma in macrophage biology, cell cycle regulation, and atherosclerosis. This review describes recent insights into the role of PPARgamma in the macrophage lineage, and its potential function in the regulation of inflammatory responses and atherosclerosis.

Animals↗
PubMed1999

Bottle contamination.

Explore the source record for details and available documents.

Anti-Infective Agents, Local↗
PubMed1998

Differential utilization of Ras signaling pathways by macrophage colony-stimulating factor (CSF) and granulocyte-macrophage CSF receptors during macrophage differentiation.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) independently stimulate the proliferation and differentiation of macrophages from bone marrow progenitor cells. Although the GM-CSF and M-CSF receptors are unrelated, both couple to Ras-dependent signal transduction pathways, suggesting that these pathways might account for common actions of GM-CSF and M-CSF on the expression of macrophage-specific genes. To test this hypothesis, we have investigated the mechanisms by which GM-CSF and M-CSF regulate the expression of the macrophage scavenger receptor A (SR-A) gene. We demonstrate that induction of the SR-A gene by M-CSF is dependent on AP-1 and cooperating Ets domain transcription factors that bind to sites in an M-CSF-dependent enhancer located 4.1 to 4.5 kb upstream of the transcriptional start site. In contrast, regulation by GM-CSF requires a separate enhancer located 4.5 to 4.8 kb upstream of the transcriptional start site that confers both immediate-early and sustained transcriptional responses. Results of a combination of DNA binding experiments and functional assays suggest that immediate transcriptional responses are mediated by DNA binding proteins that are constitutively bound to the GM-CSF enhancer and are activated by Ras. At 12 to 24 h after GM-CSF treatment, the GM-CSF enhancer becomes further occupied by additional DNA binding proteins that may contribute to sustained transcriptional responses. In concert, these studies indicate that GM-CSF and M-CSF differentially utilize Ras-dependent signal transduction pathways to regulate scavenger receptor gene expression, consistent with the distinct functional properties of M-CSF- and GM-CSF-derived macrophages.

Animals↗
PubMed1986

Immunodiagnosis of Entamoeba histolytica and Ascaris lumbricoides infections in Caucasian and aboriginal Australians.

The immunodiagnostic efficiency of an indirect immunofluorescence test (IFAT) and in vitro lymphocyte proliferative responsiveness (cell mediated immunity test, CMIT) used to measure the immunological responses of individuals with known natural Entamoeba histolytica and Ascaris lumbricoides infections, was studied under survey conditions. E. histolytica was common among Aborigines from Cherbourg, Kowanyama and Central Australia, but it was not found in Brisbane Caucasians. The protozoan was selected for the study because it was prevalent and purified antigen was commercially available. Immunodiagnosis for A. lumbricoides was made using an antigen prepared by affinity chromatography. Diagnosis based on frequency distribution of immunological data gave valid assessment of the number of infected individuals in each population studied.

Adolescent↗
PubMed1986

Fine-needle aspiration of the breast.

One of the numerous controversial issues related to the clinical management of breast cancer is the role of fine-needle aspiration (FNA). Despite its enthusiastic use in the diagnosis of thyroid nodules, its application to breast abnormalities has been accepted reluctantly. Breast FNA necessitates technical and interpretative skill and continual practice and is not 100% accurate. It also entails an additional, although moderate, expense. To assess the accuracy and determine the possible role of FNA at our institution, we performed both FNA and excisional biopsy in 100 unselected women with palpable breast nodules and correlated the cytologic and histologic findings. Our results were similar to those in previously published studies. FNA had a false-negative rate of 6%, no false-positive results, and an accuracy of 94%. After reviewing the potential assets and liabilities of this technique, we believe that breast FNA may add a measure of confidence in the diagnosis of benign breast lesions, provides a safeguard for preventing misdiagnosis of malignant lesions, and might expedite and reduce the cost of managing both primary and recurrent breast cancer.

Biopsy, Needle↗