Search PubMed⌕ Search

Biomedical subjects

P M Murphy

Publications and source records attributed to P M Murphy.

At least 109 records · Page 6Linked to original sources
PubMed1996

Cloning and functional expression of CC CKR5, a human monocyte CC chemokine receptor selective for MIP-1(alpha), MIP-1(beta), and RANTES.

We have cloned a human cDNA for a novel CC chemokine receptor (CC CKR) designated CC CKR5 that has 48-75% amino acid identity to other CC CKRs. CC CKR5 mRNA was detected constitutively in primary adherent monocytes but not in primary neutrophils or eosinophils. Macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and RANTES were all potent agonists for CC CKR5 (EC50 = 3-30 nM) when calcium flux was measured in transfected HEK 293 cells, yet the apparent binding affinities of the corresponding iodinated chemokines to intact cells expressing the receptor were low (IC50 approximately 100 nM). The calcium flux responses were completely blocked by treatment of transfected cells with pertussis toxin. These data suggest that CC CKR5 is a G(i)-coupled receptor that may mediate monocyte responses to MIP-1alpha, MIP-1beta, and RANTES.

Amino Acid Sequence↗
PubMed1996

Left ventricular mass regression early after aortic valve replacement.

BACKGROUND: Regression of left ventricular hypertrophy is an important and well-recognized salutary effect of aortic valve replacement. The earliest evidence of left ventricular mass regression after aortic valve replacement and the influence of prosthesis type are not well known, and were the focus of this study. METHODS: Transthoracic echocardiography was used to measure left ventricular mass index preoperatively and before discharge in 57 consecutive patients undergoing isolated aortic valve replacement (with or without coronary artery bypass grafting). RESULTS: Three patients were excluded from the study because of inability to obtain accurate M-mode echocardiographic images for left ventricular mass measurement preoperatively (1) or postoperatively (2). Of the remaining 54 patients, mechanical bileaflet valves were used in 19, stented tissue bioprostheses were implanted in 15, and a stentless porcine bioprosthesis was chosen for 20. Postoperative echocardiograms were obtained 4.9 +/- 2.3 days after aortic valve replacement (range, 2 to 9 days). A two-way repeated-measures analysis of variance demonstrated a significant reduction of left ventricular mass index before discharge (preoperative 141.4 +/- 45.2 g/m2, postoperative 127.5 +/- 32.8 g/m2; p = 0.0005) but no differences between prostheses. CONCLUSIONS: Left ventricular mass regression begins early after aortic valve replacement, probably because of reduction of transvalvular gradients and left ventricular wall stress. At least in the very early postoperative period, the type of prosthesis does not influence the extent of mass regression.

Aged↗
PubMed1996

Chemokine receptors: structure, function and role in microbial pathogenesis.

The chemokine superfamily is composed of at least 20 different leukocyte chemoattractants that act by binding to a family of G protein-coupled receptors. Leukocyte subtypes respond preferentially to unique but overlapping subsets of chemokines as determined by the receptor distribution, yet the receptors appear to signal through a common Gi-type G protein. Since chemokines appear to play major roles in inflammatory pathology, their receptors may be good targets for developing leukocyte selective anti-inflammatory drugs. Two chemokine receptors, CC CKRS and ONCC, function pathologically as cell entry factors respectively for human immunodeficiency virus 1, the cause of AIDS, and Plasmodium vivax, the major cause of malaria.

Amino Acid Sequence↗
PubMed1996

Comparative effects of plain and epinephrine-containing bupivacaine on the hemodynamic response to cervical plexus anesthesia in patients undergoing carotid endarterectomy.

OBJECTIVES: This study was designed to investigate whether the addition of epinephrine as a vasoconstrictor additive to local anesthetic affects the hemodynamic profile after cervical plexus block in patients presenting for carotid endarterectomy. DESIGN: A prospective, double-blind, randomized trial. SETTING: A university hospital. PARTICIPANTS: Forty patients scheduled for carotid endarterectomy under regional anesthesia (cervical plexus block). INTERVENTIONS: Patients were randomized to one of two groups. Group P (20 patients) received plain bupivacaine; group E (20 patients) received bupivacaine with epinephrine, 5 micrograms/mL. All patients received 2 mg/kg of bupivacaine, and group E received 2 micrograms/kg of epinephrine. The electrocardiogram and intra-arterial blood pressure were monitored continuously, and recordings of heart rate and blood pressure were recorded at predetermined intervals from before the block until the skin incision. RESULTS: After the block, group E developed a sustained increase in heart rate of approximately 15% (p < 0.01), whereas group P showed no change. Systolic blood pressure increased significantly with time over the study period in both groups (p < 0.01). Diastolic blood pressure increased significantly in group P (p < 0.01) but not in group E. CONCLUSIONS: Concerning cervical plexus block with bupivacaine, the use of epinephrine is associated with an increase in heart rate consistent with a beta-adrenergic effect from systemic absorption of the epinephrine. An increase in systolic blood pressure independent of the use of epinephrine also occurs, but epinephrine appears to mitigate against an increase in diastolic blood pressure.

Adult↗
PubMed1996

Development of a predictive model for growth of Listeria monocytogenes in a skim milk medium and validation studies in a range of dairy products.

A predictive model based on growth of Listeria monocytogenes in milk is described. The main aim of this work was to generate a predictive model in milk acidified with lactic acid to mimic conditions found in a range of dairy products. A complete factorial design was employed to determine the effects of pH (4.5-7.5), temperature (3-35 degrees C) and salt concentration (0-8%) on growth of the organism. There were 210 design points and growth curves were individually fitted for the Gompertz function using non-linear regression. Descriptors of the curves, such as lag phase duration (LPD), exponential growth rate (EGR) and generation time (GT) were calculated and polynomial models were developed relating these to pH, temperature and salt concentration. The selected cubic polynomial model gave acceptable predictive estimates of growth and was stable, i.e. predictions were repeatable over the range of environmental variables studied. The model was further tested to determine its capacity for predicting growth of listeria in a range of dairy foods and these validation studies confirm its usefulness as a rapid means of estimating growth of the organism under specified environmental conditions.

Animals↗
PubMed1995

Monocyte chemoattractant protein-3 is a functional ligand for CC chemokine receptors 1 and 2B.

The CC chemokine monocyte chemoattractant protein-3 (MCP-3) activates human monocytes, lymphocytes, basophils, and eosinophils. MCP-3 has been reported to induce [Ca2+]i changes in cells transfected with the monocyte-selective MCP-1 receptor 2B (CC CKR2B) and competes for 125I-MCP-1 binding on CC CKR2B, suggesting that it may mediate monocyte responses to MCP-3. However, we now show that MCP-3 is a ligand and potent agonist for the macrophage inflammatory protein-1 alpha (MIP-1 alpha)/regulated on activation, normal T expressed, and secreted protein (RANTES) receptor CC CKR1 (rank order for [Ca2+]i changes = MIP-1 alpha > MCP-3 > RANTES), which is expressed in monocytes > neutrophils > eosinophils. 125I-MCP-3 bound directly to CC CKR1 and CC CKR2B (Ki = 8 and 7 nM, respectively). Binding to CC CKR1 was competed by all CC chemokines tested except MCP-1. In contrast, binding to CC CKR2B was competed only by MCP-3 and MCP-1. Both MCP-1 and MCP-3 were equipotent agonists (EC50 = 10 nM for [Ca2+]i changes). Thus, MCP-3 is a functional ligand for both CC CKR1 and CC CKR2B, which otherwise have distinct selectivities for CC chemokines. These data suggest that monocyte responses to MCP-3 could be mediated by both CC CKR2B and CC CKR1, whereas eosinophil responses to MCP-3 could be mediated by CC CKR1.

Amino Acid Sequence↗
PubMed1995

Cloning and chromosomal mapping of three novel genes, GPR9, GPR10, and GPR14, encoding receptors related to interleukin 8, neuropeptide Y, and somatostatin receptors.

We employed the polymerase chain reaction and genomic DNA library screening to clone novel human genes, GPR9 and GPR10, and a rat gene, GPR14. GPR9, GPR10, and GPR14 each encode G protein-coupled receptors. GPR10 and GPR14 are intronless within their coding regions, while GPR9 contains at least one intron. The receptor encoded by GPR9 shares the highest identity with human IL-8 receptor type B (38% overall and 53% in the transmembrane regions), followed by IL-8 receptor type A (36% overall and 51% in the transmembrane domains). GPR10 encodes a receptor that shares highest identity with the neuropeptide Y receptor (31% overall and 46% in the transmembrane domains). The receptor encoded by GPR14 shares highest identity with the somatostatin receptor SSTR 4 (27% overall and 41% in the transmembrane domains). Fluorescence in situ hybridization analysis localized GPR9 to chromosome 8p11.2-p12 and GPR10 to chromosome 10q25.3-q26.

Amino Acid Sequence↗
PubMed1995

Mapping of the mouse macrophage inflammatory protein-1 alpha receptor gene Scya3r and two related mouse beta chemokine receptor-like genes to chromosome 9.

Macrophage inflammatory protein-1 alpha (MIP-1 alpha) and RANTES are members of the beta chemokine family of leukocyte chemoattractants. We have previously cloned three mouse genes by cross-hybridization with the human MIP-1 alpha/RANTES receptor gene CMKBR1. One of the mouse genes, Scya3r, encodes a functional MIP-1 alpha receptor. The functions of the other two, Scya3r-rs1 and Scya3r-rs2, are not known. We have now mapped Scya3r, Scya3r-rs1, and Scya3r-rs2 to chromosome 9, in a region of conserved synteny with the location of CMKBR1. Thus, like chemokine genes and alpha chemokine receptor genes, this group of beta chemokine receptor genes arose by tandem duplication.

Animals↗
PubMed1995

Cloning and differential tissue-specific expression of three mouse beta chemokine receptor-like genes, including the gene for a functional macrophage inflammatory protein-1 alpha receptor.

Macrophage inflammatory protein-1 alpha (MIP-1 alpha) and RANTES, members of the beta chemokine family of leukocyte chemoattractants, bind to a common seven-transmembrane-domain human receptor. We have now cloned three related mouse genes: one for a selective MIP-1 alpha receptor (MIP-1 alpha R) and two for orphan receptors provisionally designated MIP-1 alpha receptor-like 1 and 2 (MIP-1 alpha RL1 and 2). Their deduced sequences are 80, 62, and 63% identical to the human MIP-1 alpha/RANTES receptor, respectively. K562 cells stably transfected with MIP-1 alpha R specifically bound 125I-human MIP-1 alpha and 125I-human RANTES with high affinity. The rank order of beta chemokine competition for 125I-human MIP-1 alpha binding was human MIP-1 alpha > mouse MIP-1 alpha approximately RANTES approximately MIP-1 beta > MCP-1. However, human RANTES was approximately 100-fold less potent as a calcium-mobilizing agonist for MIP-1 alpha R than either human or mouse MIP-1 alpha, which matched the selectively of mouse leukocytes for calcium mobilization by MIP-1 alpha and RANTES. No other beta or alpha chemokines tested were agonists for MIP-1 alpha R. RNA for all three genes was detected in mouse leukocytes, but unique patterns of expression were identified in solid organs: MIP-1 alpha R, heart, spleen, and lung; MIP-1 alpha RL1, skeletal muscle; and MIP-1 alpha RL2, spleen and liver. These data identify potentially important new targets for beta chemokine action in the mouse.

Amino Acid Sequence↗
PubMed1995

Cloning and functional expression of a human eosinophil CC chemokine receptor.

Eosinophils undergo chemotaxis, degranulate, and exhibit [C2+]i changes in response to the human CC chemokines macrophage inflammatory protein (MIP)-1 alpha, regulated on activation, normal T expressed and secreted (RANTES), and monocyte chemoattractant protein-3 (MCP-3), but the receptors involved have not been defined. We have isolated a human cDNA encoding the first eosinophil-selective chemokine receptor, designated CC chemokine receptor 3 (CC CKR3). CC CKR3 is a seven-transmembrane domain G protein-coupled receptor most closely related to the previously reported monocyte- and neutrophil-selective receptor CC CKR1 (also known as the MIP-1 alpha/RANTES receptor). When [Ca2+]i changes were monitored in stably transfected human embryonic kidney 293 cells, MIP-1 alpha and RANTES were both potent agonists for CC CKR3 and CC CKR1. However, MIP-1 beta was also an agonist for CC CKR3 but not CC CKR1; MCP-3 was an agonist for CC CKR1 but not CC CKR3. CC CKR3 may be one of the host factors responsible for selective recruitment of eosinophils to sites of inflammation.

Amino Acid Sequence↗
PubMed1995

Cloning, chromosomal localization, and RNA expression of a human beta chemokine receptor-like gene.

A human cDNA encoding a putative G protein-coupled receptor designated chemokine beta receptor-like 1 (CMKBRL1) was isolated from an eosinophilic leukemia library. Its deduced sequence is approximately 40% identical to previously cloned receptors for the beta chemokines macrophage inflammatory protein-1 alpha (MIP-1 alpha), RANTES, and monocyte chemoattractant protein-1 (MCP-1), which are chemoattractants for blood leukocytes, and is 83% identical to the product of the orphan rat cDNA RBS 11. Like the MIP-1 alpha/RANTES receptor, CMK-BRL1 is encoded by a small, single-copy gene that maps to chromosome 3p21 and is expressed in leukocytes. However, two screening assays with a broad panel of chemokines failed to identify its ligand. CMKBRL1 mRNA was detectable by Northern blot hybridization in neutrophils and monocytes, but not eosinophils, and was also found in eight solid organs that were tested with particularly high expression in brain. The RNA distribution of the known beta chemokine receptors was overlapping but distinct from that of CMKBRL1. MIP-1 alpha/RANTES receptor mRNA was detectable in neutrophils, monocytes, eosinophils, and in all eight solid organs tested, with particularly high expression in placenta, lung, and liver. MCP-1 receptor mRNA was found in monocytes, lung, liver, and pancreas. These results suggest that the ligand for the putative CMKBRL1 receptor is a beta chemokine that targets both neutrophils and monocytes. Moreover, the RNA distributions suggest that CMKBRL1, the MIP-1 alpha/RANTES receptor, and the MCP-1 receptor may have both overlapping and distinct biological roles.

Amino Acid Sequence↗
PubMed1994

A high potency nonformylated peptide agonist for the phagocyte N-formylpeptide chemotactic receptor.

Analysis of synthetic tri- and tetrapeptides has previously indicated that N-formylation is required for high biological activity when they react with the phagocyte N-formylpeptide receptor, suggesting that the natural ligand for the receptor is from bacterial and/or mitochondrial sources. To explore this requirement further, we synthesized the pentapeptide methionyl-norleucyl-leucyl-phenylalanyl-phenylalanine (MNleLFF) and studied the effects of different NH2-terminal modifications on its activity. N-formyl-MNleLFF induced transient alterations of [Ca2+]i and superoxide production in human neutrophils with 10- and 100-fold greater potency, respectively, than the proto-type N-formylpeptide, N-formylmethionyl-leucyl-phenylalanine (fMLF). Surprisingly, N-acetyl-MNleLFF was a potent as N-formyl-MNleLFF. Moreover, the unacylated counterpart H-MNleLFF was also highly active, having an EC50 for calcium mobilization of 10 nM, and for respiratory burst activation of 100 nM. All three pentapeptides could completely desensitize calcium transients elicited by stimulation of neutrophils with fMLF, whereas the neutrophil chemoattractants C5a and interleukin 8 only weakly affected fMLF-induced transients, suggesting that they activate neutrophils via the same receptor as fMLF. Finally, all three pentapeptides activated the recombinant human N-formylpeptide receptor expressed in frog oocytes, but did not effectively activate related phagocyte receptors. These data broaden the potential sources of natural ligands for the N-formyl-peptide receptor from N-formylated bacterial and mitochondrial products to other nonformylated endogenous peptides.

Amino Acid Sequence↗
PubMed1994

Human cytomegalovirus open reading frame US28 encodes a functional beta chemokine receptor.

Human cytomegalovirus infects epithelial, smooth muscle, and white blood cells in vivo causing acute, latent, and chronic infections. A data base search revealed that the amino acid sequence of the putative protein encoded by open reading frame US28 of human cytomegalovirus is approximately 30% identical to those of the mammalian leukocyte receptors for alpha and beta chemokines. This suggested that US28 was originally copied from a human chemokine receptor gene, perhaps to provide the virus with a selective advantage through molecular mimicry. Chemokines regulate the trafficking and activation of mammalian leukocytes and activate calcium-mobilizing, heptahelical, G protein-coupled receptors. We now show that US28 encodes a promiscuous calcium-mobilizing receptor for the beta chemokines RANTES (regulated upon activation, normal T expressed and secreted), macrophage inflammatory protein-1 alpha, and monocyte chemoattractant protein-1, but not for the alpha chemokines interleukin-8 or gamma IP10. The chemokine selectivity of the US28 product is distinct from that of known mammalian beta chemokine receptors. This finding suggests a role for beta chemokines in the pathogenesis of human cytomegalovirus infection by transmembrane signaling via the product of US28.

Amino Acid Sequence↗
PubMed1994

Comparison of the genomic organization and promoter function for human interleukin-8 receptors A and B.

Human neutrophils are highly responsive to the chemokine interleukin-8 (IL-8) owing to high levels of expression of two related receptors encoded by the single copy genes il8ra and il8rb located on chromosome 2q34-q35. To identify nuclear factors that regulate the expression of IL-8 receptors, we have first defined the organization of both genes and characterized their functional promoters. il8ra and il8rb span approximately 4 and 12 kilobase pairs of genomic DNA, respectively. In both cases, the open reading frame resides on a single exon. In contrast, the 5'-untranslated regions are more complex. For il8ra, it is formed from two exons, whereas for il8rb, seven distinct neutrophil mRNAs are formed by alternative splicing of 11 exons. One of the splice variants, designated IL8RB3, is the predominant form for il8rb. Two equally abundant mRNAs for il8ra, 2.0 and 2.4 kilobases in length, are expressed in neutrophils and arise from usage of two alternative polyadenylation signals. Primer extension analysis identified two major transcription start points for il8ra and 11 for il8rb. Regions extending 300 base pairs (bp) upstream from exon 1 of il8ra and 81 bp upstream from exon 3 of il8rb have limited sequence similarity but had strong constitutive promoter activity when cloned upstream from a chloramphenicol acetyltransferase-encoding reporter gene and transiently transfected into surrogate myeloid (HL-60, and U-937) and lymphoid (Jurkat) cell lines. Neither of these regions has sequences corresponding to classic promoter elements. In contrast, a region 643 base pairs upstream from exon 1 of il8rb had relatively low levels of constitutive promoter activity in all three cell environments, and a conserved TATA element is located 47 bp upstream of the 5'-end of exon 1. Thus, despite marked differences in the complexity of their genomic organization, il8ra and il8rb encode products that are similar in structure, function, and the major cell type of expression.

Base Sequence↗
PubMed1994

Differential expression of members of the N-formylpeptide receptor gene cluster in human phagocytes.

The human genes for two N-formylpeptide phagocyte chemoattractant receptors (gene symbols FPR1 and FPRL1) cross-hybridize with each other and with FPRL2, a human gene of unknown expression and function. The FPR1 product is approximately 1000-fold more sensitive than the FPRL1 product to N-formylpeptides. We now report cloning of the first cDNA for FPRL2 and the first description of the RNA distribution in normal human phagocytes for all three genes. FPR1 and FPRL1 are expressed in neutrophils and monocytes. In contrast, FPRL2 RNA is detectable in monocytes but not in neutrophils, and its product could not be activated by N-formylpeptides. Thus, the regulation of FPRL2 gene expression in vivo differs from FPR1 and FPRL1.

Animals↗