Elective experience in Sri Lanka--Summer 1993.
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Education, Dental↗
Biomedical subjects
A Kelly
Publications and source records attributed to A Kelly.
The major histocompatibility complex-encoded proteasome component LMP7: alternative first exons and post-translational processing.
The LMP7 gene maps to the major histocompatibility complex class II region. The derived protein sequence shares homology with N-terminal amino acid sequence from proteasome subunits (Glynne, R., Powis, S. H., Beck, S., Kelly, A., Kerr, L.-A. and Trowsdale, J., Nature 1991. 353: 357) and it has been suggested that LMP7 is involved in the degradation of endogenous antigens prior to their presentation through class I (Robertson, M., Nature 1991. 353: 300). We have isolated a second LMP7 transcript which has a different first exon to the published sequence. Both transcripts were expressed in cell lines from a number of tissues and both responded to interferon-gamma. An anti-LMP7 antiserum precipitated proteins similar in their migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis to those precipitated by an anti-proteasome serum. Western blot analysis of anti-proteasome precipitates demonstrated that the LMP7 protein is incorporated into the proteasome but has a molecular mass of 23 kDa, 7 kDa smaller than expected fro the derived protein sequence of either of the cDNA. A pulse-chase experiment indicated that post-translational cleavage of the LMP7 N terminus precedes the formation of the 23-kDa proteasome subunit. To our knowledge, LMP7 provides the first biochemical evidence for such processing of proteasome components.
Alternative Splicing↗
Personal and family distress in homeless adolescents.
Previous research has indicated that homeless children exhibit high rates of behavioral and emotional problems and come from families characterised by conflict and rejection. Further, some evidence exists to show that family variables may relate to adolescent distress differently for homeless males and females. In this study, 117 homeless adolescents were compared to a sample of non-homeless youths on the self reported incidence of personal and family problems. The homeless children reported the highest incidence of all behavioral and emotional problems, parental marital discord, overprotection, and the lowest levels of parental care and acceptance. Sex effects were not evident in reported levels of personal or family problems. However, substantially more variance in the adolescents level of behavioral and emotional disturbance was predictable from family measures for females than males. Overall, the results point to the importance of incorporating family distress models in the understanding and remediation of adolescent homelessness.
Adolescent↗
DNA sequence analysis of 66 kb of the human MHC class II region encoding a cluster of genes for antigen processing.
The genomic sequence of a 66,109 bp long region within the human MHC has been determined by manual and automated DNA sequencing. From cDNA mapping and sequencing data it is known that this region contains a cluster of at least four genes that are believed to be involved in antigen processing. Here, we describe the genomic organization of these genes, which comprise two proteasome-related genes (LMP2 and LMP7), thought to be involved in the proteolytic degradation of cytoplasmic antigens and two ABC transporter genes (TAP1 and TAP2), thought to be involved in pumping of the degraded peptides across the endoplasmic reticulum membrane. Analysis of the sequence homology and the intron/exon structures of the corresponding genes suggests that one gene pair arose by duplication from the other. Comparison of the available sequence data from other organisms shows striking conservation (70 to 84%) of this gene cluster in human, mouse and rat. The presence of several potential interferon stimulated response elements (ISREs) is in agreement with the experimentally observed up-regulation of these genes with gamma-interferon.
Amino Acid Sequence↗
Hypoxia increases stimulus-induced PAF production and release from human umbilical vein endothelial cells.
Hypoxia alters endothelial cell function and metabolism. Since PAF is synthesized by endothelial cells and capable of modulating endothelial cell responses, we investigated the effect of hypoxia on synthesis and release of PAF from endothelial cells. We found: (1) Approx. 90% of the radylPAF derivative in stimulated endothelial cells is acylPAF. (2) Acute hypoxic (15 min-1 h) priming increased ionophore- and thrombin-induced radylPAF accumulation. (3) Long-term hypoxic exposure increased radylPAF accumulation at 24 and 48 h in the presence of ionophore. (4) Bioactive PAF was released into media and hypoxia and ionophore synergistically increased PAF release. (5) Hypoxia and ionophore stimulation increased phospholipase A2 activity and decreased acetylhydrolase activity in endothelial cells. We conclude that hypoxia and ionophore increase PAF synthesis and release from endothelial cells.
1-Alkyl-2-acetylglycerophosphocholine Esterase↗
Location of MHC-encoded transporters in the endoplasmic reticulum and cis-Golgi.
Immune recognition of intracellular proteins is mediated by major histocompatibility complex (MHC) class I molecules that present short peptides to cytotoxic T cells. Evidence suggests that peptides arise by cleavage of proteins in the cytoplasm and are transported by a signal-independent mechanism into a pre-Golgi region of the cell, where they take part in the assembly of class I heavy chains with beta 2-microglobulin (reviewed in refs 5-7). Analysis of cells that have defects in class I molecule assembly and antigen presentation has shown that this phenotype can result from mutations in either of the two ABC transporter genes located in the class II region of the MHC. This suggested that the protein complex encoded by these two genes transports peptides from the cytosol into the endoplasmic reticulum. Here we report additional evidence by showing that the transporter complex is located in the endoplasmic reticulum membrane and is probably oriented with its ATP-binding domains in the cytosol.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Polymorphism in a second ABC transporter gene located within the class II region of the human major histocompatibility complex.
Recent studies have identified genes within the major histocompatibility complex (MHC) that may play a role in presentation of antigenic peptides to T cells. We have previously described RING4, a gene within the human MHC class II region that has sequence homology with members of the ABC ("ATP-binding cassette") transporter superfamily. We now report the nucleotide sequence of RING11, a second ABC transporter gene located approximately 7 kilobases telomeric to RING4, RING11 is gamma-interferon inducible, a property shared with other genes involved in antigen presentation. Comparison between the amino acid sequences of RING11 and RING4 reveals strong homology. We propose that they form a heterodimer that transports peptides from the cytoplasm into the endoplasmic reticulum. We have identified two RING11 alleles, which differ in the length of their derived protein sequence by 17 amino acids. The more common of these alleles is present in a Caucasoid population at a frequency of 79%.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Assembly and function of the two ABC transporter proteins encoded in the human major histocompatibility complex.
Presentation of cytoplasmic antigens to class I-restricted cytotoxic T cells implied the existence of a specialized peptide transporter. For most class I heavy chains, association with peptides of the appropriate length is required for stable assembly with beta 2-microglobulin. Mutant cells RMA-S and .174/T2 neither assemble stable class I molecules nor present intracellular antigens, and we have suggested that they have lost a function required for the transport of short peptides from the cytosol to the endoplasmic reticulum. The genetic defect in .174 has been localized to a large deletion in the class II region of the major histocompatibility complex, within which two genes (RING4 and RING11) have been identified that code for 'ABC' (ATP-binding cassette) transporters. We report here that the protein products of these two genes assemble to form a complex. Defects in either protein result in the formation of unstable class I molecules and loss of presentation of intracellular antigens. The molecular defect in a new mutant, BM36.1, is shown to be in the ATP-binding domain of the RING11/PSF2 protein. This is in contrast to the mutant .134, which lacks the RING4/PSF1 protein.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Postnatal depression and antenatal morbidity.
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Adult↗
Endotoxin and hypoxia-induced intestinal necrosis in rats: the role of platelet activating factor.
We have previously shown that intravascular platelet activating factor (PAF) causes ischemic bowel necrosis in rats morphologically similar to neonatal necrotizing enterocolitis (NEC). Because endotoxin (LPS) and hypoxia are risk factors for NEC, we studied their effect on PAF metabolism and the development of intestinal injury. Young male Sprague-Dawley rats were anesthetized with pentobarbital and divided into six experimental groups: 1) control, 2) LPS alone (2 mg/kg), 3) hypoxia alone (5% O2), 4) LPS+hypoxia, 5) WEB 2086 (PAF antagonist)+LPS+hypoxia, and 6) SRI 63-441 (PAF antagonist)+LPS+hypoxia. Evaluations included blood pressure recording, superior mesenteric artery blood flow, arterial blood gas, white blood cell count, hematocrit, plasma PAF, plasma acetylhydrolase, plasma tumor necrosis factor, intestinal perfusion, and intestinal injury at 3 h. We found that LPS+hypoxia synergistically contributed to hypotension (mean blood pressure 27 +/- 5.6% baseline versus 101 +/- 3.9% control), metabolic acidosis (pH 7.05, base deficit 24 mEq/L), hemoconcentration, decreased superior mesenteric artery blood flow (2.2 +/- 0.3 mL/min versus 5.8 +/- 0.2 mL/min control), and intestinal injury. The morbidities resulting from LPS+hypoxia were partially or completely prevented by PAF antagonists. In addition, animals treated with LPS+hypoxia had neutropenia, elevated plasma acetylhydrolase, and elevated plasma TNF. These results suggest that endogenous PAF may contribute to LPS+hypoxia-induced intestinal hypoperfusion and necrosis.
Animals↗
A homologue of the Drosophila female sterile homeotic (fsh) gene in the class II region of the human MHC.
The RING3 gene maps in the class II region of the human major histocompatibility complex, at a CpG island distal of the HLA-DNA gene. RING3 cDNAs were obtained from a T cell cDNA library and the longest (4 kb) was sequenced. The sequence contained an open reading frame encoding a protein of 754 amino acids. A screen of protein databases revealed striking homology between the RING3 protein and the Drosophila female sterile homeotic gene (fsh) which is implicated in the establishment of segments in the early embryo. Partial sequence homology was also observed with some other proteins involved in cell cycle control (CCG1), cell division (ftsA) and regulation of cell growth (gamma interferons). This highly conserved gene may play an important role in human development. In addition, its location in the MHC class II region may be related to some HLA-associated diseases.
Amino Acid Sequence↗
Marketing: Part 2 of 4. Shaping and selling the health visiting image.
Integral to the marketing process is the image projected to the consumer of the product s/he is being asked to buy. In the second of this series of articles on marketing health visiting, ANNE KELLY examines past and present images of health visiting and suggests ways to market a new image in keeping with clients' needs and health policies.
Attitude to Health↗
Second proteasome-related gene in the human MHC class II region.
Antgen processing involves the generation of peptides from cytosolic proteins and their transport into the endoplasmic reticulum where they associate with major histocompatibility complex (MHC) class I molecules. Two genes have been identified in the MHC class II region, RING4 and RING11 in humans, which are believed to encode the peptide transport proteins. Attention is now focused on how the transporters are provided with peptides. The proteasome, a large complex of subunits with multiple proteolytic activities, is a candidate for this function. Recently we reported a proteasome-related sequence, RING10, mapping between the transporter genes. Here we describe a second human proteasome-like gene, RING12, immediately centromeric of the RING4 locus. Therefore RING12, 4, 10 and 11 form a tightly linked cluster of interferon-inducible genes within the MHC with an essential role in antigen processing.
Amino Acid Sequence↗
A proteasome-related gene between the two ABC transporter loci in the class II region of the human MHC.
It is now possible to paint a detailed picture of how cytoplasmic proteins are handled by the immune system. They are apparently degraded in the cytoplasm into peptides. These are then transported into the endoplasmic reticulum where they encounter class I major histocompatibility complex (MHC) molecules. Once loaded with peptide, the HLA molecules move through the Golgi apparatus to the cell membrane. Until recently, it had not been established how peptides without signal sequences cross the ER membrane. However, a number of papers have now described a pair of membrane transporter genes of the ABC (ATP-binding cassette) super-family which are attractive candidates for this function. Both transporter genes, which may encode two halves of a heterodimer, are situated in the class II region of the MHC. There is evidence that other putative components of the processing machinery, the LMPs (low molecular mass polypeptides), are also encoded in the MHC. Similarities between the properties of the LMPs and a large intracellular protease complex, called proteasome, have led to the suggestion that LMPs are involved in processing antigens. We have now identified a human gene with sequence homology to proteasome components. Remarkably, this gene maps between the two putative peptide transporter genes.
Amino Acid Sequence↗
Experimental necrotizing enterocolitis: the role of polymorphonuclear neutrophils.
Polymorphonuclear neutrophils (PMNs) play an important role in inflammation. Activated PMNs adhere to the vascular wall and release reactive oxygen radicals and enzymes, producing vascular injury. In the present study, we investigated whether PMNs play an important role in the pathogenesis of experimental necrotizing enterocolitis (NEC). NEC was induced in rats using platelet activating factor (PAF, 1 microgram/kg) and bacterial endotoxin (LPS, 1 mg/kg) intravenously. Neutropenia was accomplished by parenteral injection of Vinblastine (VB, 0.75 mg/kg) 4 days before the experiment to deplete the total white blood cell (WBC) and neutrophil counts. The animals were divided into 4 groups: (1) 1 microgram/kg PAF; (2) 1 mg/kg LPS; (3) 1 microgram/kg PAF + 1 mg/kg LPS; and (4) PMN depleted, 1 microgram/kg PAF + 1 mg/kg LPS. Combined administration of PAF and LPS produced prolonged hypotension (blood pressure 53.5 +/- 13.8 mm Hg at 2 hours), leukopenia (4,062 +/- 497.4), hemoconcentration (hematocrit 44.5% +/- 1.1%), reduced intestinal perfusion (74% +/- 13.3%), and segmental bowel necrosis. However, in VB-treated animals combined PAF + LPS induced only mild hypotension (84.3 +/- 9.2 mm Hg at 2 hours) and no hemoconcentration. In these animals the intestinal perfusion was normal, no bowel necrosis was observed, and the intestinal myeloperoxidase activity (.0034 +/- .0017 U/g tissue) was significantly lower than that of the nondepleted group (.0075 +/- .0012 U/g tissue). We conclude that the presence of neutrophils and/or neutrophil products play a major role in the pathogenesis of NEC.
Animals↗
Platelet activating factor-induced shock and intestinal necrosis in the rat: role of endogenous platelet-activating factor and effect of saline infusion.
BACKGROUND AND METHODS: The mechanism of ischemic bowel necrosis induced by platelet-activating factor is unclear. Since intestinal hypoperfusion is observed after platelet-activating factor injection, we hypothesized that mesenteric vasoconstriction is the mechanism of bowel injury. The present study investigated the effects of saline infusion on platelet activating factor-induced bowel necrosis and its mechanism. Male Sprague-Dawley rats were divided into four groups: group A consisted of sham-operated rats; group B received platelet-activating factor (1.5 micrograms/kg iv); group C received platelet-activating factor and saline (0.097 mL/min iv); group D received platelet-activating factor and WEB 2086 (platelet-activating factor antagonist). RESULTS: Saline infusion largely reversed platelet activating factor-induced hypotension, hemoconcentration, and reduction of the superior mesenteric arterial blood flow. Saline infusion also ameliorated platelet activating factor-induced bowel injury, although a mild-to-moderate degree of necrosis still developed focally. In addition, saline prevented the platelet activating factor-induced increase in intestinal platelet-activating factor production. Saline also prevented the increase in intestine leukocyte number, as estimated by myeloperoxidase activity. CONCLUSIONS: Saline infusion is an effective treatment for platelet activating factor-induced shock and intestinal necrosis. However, focal bowel injury is still observed, suggesting that other factors besides hemodynamic changes contribute to the development of tissue injury. We also showed that, in vivo, platelet-activating factor stimulates its own synthesis via a positive feedback loop, which could be blocked by intravascular volume expansion with saline.
Animals↗
Nutrition information systems and data quality requirements.
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Data Collection↗