Search PubMed⌕ Search

Biomedical subjects

E A Hughes

Publications and source records attributed to E A Hughes.

At least 19 recordsLinked to original sources
PubMed2006

Efficacy, safety and LDL-C goal attainment of ezetimibe 10 mg-simvastatin 20 mg vs. placebo-simvastatin 20 mg in UK-based adults with coronary heart disease and hypercholesterolaemia.

It is increasingly accepted that more intensive lipid-lowering treatment is associated with greater cardiovascular risk reductions in patients with coronary heart disease (CHD), thus providing a rationale for more aggressive LDL-cholesterol (LDL-C) targets. Ezetimibe in combination with statin therapy provides an additional approach to lipid management by utilising the additive action of two different mechanisms of LDL-C reduction. In this multicentre, randomised, double-blind, placebo-controlled study, a total of 98 men and 55 women with CHD and primary hypercholesterolaemia, naïve to statin therapy, were randomised to receive treatment for 6 weeks with either ezetimibe 10 mg-simvastatin 20 mg (n = 77) or placebo-simvastatin 20 mg (n = 75). At 6 weeks, ezetimibe 10 mg-simvastatin 20 mg provided a mean additional LDL-C reduction of 14.6% (95% CI 10.1-19.1) compared with simvastatin monotherapy (p < 0.0001). Moreover, a higher proportion of patients on ezetimibe/simvastatin achieved the National Standard Framework LDL-C standard (<3.0 mmol/l; 93% vs. 75%, p < 0.001) or the new Joint British Societies (JBS 2) goal of LDL-C < 2.0 mmol/l (49.3% vs. 11.1%, p < 0.001). On logistic regression analysis, the odds ratio of achieving target LDL-C with ezetimibe 10 mg-simvastatin 20 mg was 5.1 (95% CI 1.8-15.0) times higher than with simvastatin monotherapy (p = 0.003). Clinical chemistry profiles and proportions of adverse events were similar in both groups at baseline and follow-up. In conclusion, ezetimibe 10 mg-simvastatin 20 mg is a practical, effective and safe option for the treatment of primary hypercholesterolaemia in CHD patients, and brings more patients to new aggressive cholesterol targets compared with simvastatin 20 mg monotherapy.

Adult↗
PubMed1999

The N-terminal region of tapasin is required to stabilize the MHC class I loading complex.

Tapasin mediates the binding of MHC class I molecules to the transporter associated with antigen processing (TAP). Deletion mutants of tapasin were used to examine the effect of tapasin on interactions within the MHC class I complex. Binding to TAP is mediated by the C-terminal region of tapasin. Michaelis-Menten analysis of peptide transport shows that this interaction is sufficient to increase TAP levels without significantly affecting the intrinsic translocation rate. Weak interactions exist between MHC class I molecules and TAP in the absence of tapasin, and between free heavy chains and TAP-tapasin complexes in the absence of beta2-microglobulin. The N-terminal 50 residues of tapasin constitute the key element which converts the sum of these weak interactions into a stable complex.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

The thiol oxidoreductase ERp57 is a component of the MHC class I peptide-loading complex.

The proper folding and assembly of major histocompatibility complex (MHC) class I molecules in the endoplasmic reticulum (ER) is an intricate process involving a number of components. Nascent heavy chains of MHC class I molecules, translocated into the ER membrane, are rapidly glycosylated and bind the transmembrane chaperone calnexin. In humans, after dissociation from calnexin, fully oxidized MHC class I heavy chains associate with beta 2-microglobulin (beta 2m) and the soluble chaperone calreticulin. This complex interacts with another transmembrane protein, tapasin, which is believed to assist in MHC class I folding as well as in mediating the interaction between assembling MHC class I molecules and the transporter associated with antigen processing (TAP). The TAP heterodimer (TAP1-TAP2) introduces the final component of the MHC class I molecule by translocating peptides, predominately generated by the proteasome, from the cytosol into the ER where they can bind dimers of beta 2M and the MHC class I heavy chain. Recently, the thiol oxidoreductase ERp57--also known as GRP58, ERp61, ER60, Q2, HIP-70, and CPT and first misidentified as phospholipase C-alpha--has been shown to bind in conjunction with calnexin or calreticulin to a number of newly synthesized ER glycoproteins when their N-linked glycans are trimmed by glucosidases I and II. It was speculated that ERp57 is a generic component of the glycan-dependent ER quality control system. Here, we show that ERp57 is a component of the MHC class I peptide-loading complex. ERp57 might influence the folding of MHC class I molecules at a critical step in peptide loading.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Induction of transporter associated with antigen processing by interferon gamma confers endothelial cell cytoprotection against natural killer-mediated lysis.

T lymphocytes react minimally with nonactivated endothelial cells (ECs). However, natural killer (NK) lymphocyte interactions with resting ECs are rapid, avid, and result in endothelial activation and/or cytotoxicity. The molecular basis for these interactions and EC sensitivity to NK-mediated lysis is unclear. To address the EC-specific nature of NK sensitivity, we used syngeneic human umbilical vein ECs, dermal microvascular ECs, dermal fibroblasts, and B lymphoblastoid cell lines in calcein-AM retention NK assays with allogeneic NK effector cells and found the EC lines consistently more NK-sensitive. Because NK inhibitory receptors are engaged by membrane major histocompatibility complex (MHC) I molecules and MHC I-deficient targets are NK-sensitive, we investigated the quantitative levels of membrane MHC I on the panel of syngeneic lines. Highly sensitive ECs expressed similar (or higher) levels of membrane MHC I than their syngeneic NK-resistant counterparts. Pretreatment of ECs with gamma interferon (IFN-gamma) conferred protection against NK-mediated lysis, with much more rapid kinetics (2-6 hr) than those required for membrane MHC I hyperinduction (>8 hr). These kinetics are consistent with induction of transporter associated with antigen processing (TAP) expression and function. As opposed to NK-resistant cell lines, TAP-1 was undetectable in resting ECs. Recombinant expression of the TAP inactivator ICP47 by adenoviral-mediated transduction was used to selectively inhibit IFN-gamma-mediated EC TAP function. ICP47 expression abrogated EC cytoprotection conferred by IFN-gamma. We demonstrate a relationship between both basal and induced TAP-1 expression/function and EC sensitivity to NK-mediated cytotoxicity. We discuss the influence of an induced MHC I-associated peptide repertoire on vascular vulnerability to cytotoxic lymphocytes.

B-Lymphocytes↗
PubMed1997

Protein degradation: the ins and outs of the matter.

In eukaryotic cells, nascent membrane or secretory proteins are translocated into the endoplasmic reticulum through the Sec61p translocation channel; recent evidence suggests that, if they fail to achieve a native conformation, they are translocated back into the cytosol by the same route and degraded by the proteasome.

Animals↗
PubMed1997

Misfolded major histocompatibility complex class I heavy chains are translocated into the cytoplasm and degraded by the proteasome.

N-acetyl-L-leucyl-L-leucyl-L-norleucinal (LLnL), which reversibly inhibits the proteasome in addition to other proteases, and a more specific irreversible inhibitor of the proteasome, lactacystin, were found to cause the accumulation of major histocompatibility complex (MHC) class I heavy chains in the cytosol of the beta2-microglobulin-deficient cell line Daudi and the TAP-deficient cell line .174. These cell lines, which are severely impaired in their ability to fold MHC class I heavy chain, showed an accumulation of soluble class I heavy chains at different rates over a period of hours in the presence of LLnL. The accumulation of soluble class I heavy chains in the presence of either LLnL or lactacystin was easily revealed in Daudi and .174 but almost undetectable in a Daudi transfectant expressing beta2-microglobulin and in 45.1, the wild-type parent of .174. The soluble class I heavy chain was also found to be devoid of its N-linked glycan and to be located in the cytosol. When the gene for ICP47, a herpes simplex virus protein that blocks the translocation of peptides into the endoplasmic reticulum, was transfected into 45.1, a similar accumulation of soluble MHC class I heavy chain was detectable. These data suggest that in cells where the MHC class I molecule is unable to assemble properly, the misfolded heavy chain is removed from the endoplasmic reticulum to the cytosol, deglycosylated, and degraded by the proteasome.

Acetylcysteine↗
PubMed1997

Development of an instrument to measure knowledge in individuals with rheumatoid arthritis: the ACREU rheumatoid arthritis knowledge questionnaire.

OBJECTIVE: Education is an important component of community based rehabilitation programs for people with rheumatoid arthritis (RA). This study describes the development of a questionnaire to measure knowledge in this context. METHODS: Items were generated using focus group methodology and covered the domains of prognosis, pain management, medications, joint protection, energy conservation, exercise, and coping strategies. RESULTS: After extensive pretesting, the questionnaire was administered to 252 people with RA. The final 31 item questionnaire had acceptable internal consistency (Cronbach's alpha: 0.76, n = 185), test-retest reliability (r = 0.91, p < or = 0.001), content and construct validity. Sensitivity to change was confirmed in the context of a 6 week home based physiotherapy educational intervention. CONCLUSION: The RA knowledge questionnaire is a reliable, valid, and sensitive instrument for measuring the effect of a RA educational intervention.

Adult↗
PubMed1996

The protease inhibitor, N-acetyl-L-leucyl-L-leucyl-leucyl-L-norleucinal, decreases the pool of major histocompatibility complex class I-binding peptides and inhibits peptide trimming in the endoplasmic reticulum.

N-acetyl-L-leucyl-L-leucyl-L-norleucinal, (LLnL), which inhibits proteasomes in addition to other proteases, was found to prolong the association of major histocompatibility complex class I molecules with the transporters associated with antigen processing (TAP), and to slow their transport out of the endoplasmic reticulum (ER). LLnL induced a reversible accumulation of ubiquitinated proteins and changed the spectrum of peptides bound by class I molecules. These effects can probably be attributed to proteasome inhibition. Unexpectedly, in the TAP-deficient cell line .174, the rate of intracellular transport of human histocompatibility leukocyte antigen (HLA) A2 was also reduced by LLnL, and the generation of most HLA-A2-associated signal sequence peptides was inhibited. The inhibition of HLA-A2 transport in .174 cells was found to be less sensitive to LLnL than in wild-type cells, and a similar difference was found for a second protease inhibitor, benzyloxycarbonyl-L-leucyl-L-leucyl-L-phenylalanilal. These data suggest that under some conditions such inhibitors can block trimming of peptides by an ER peptidase in addition to inhibiting cytosolic peptide generation.

Amino Acid Sequence↗
PubMed1996

Short side chain sterols from the tunicate Polizoa opuntia.

The sterol composition of the Patagonian tunicate Polizoa opuntia was examined, and twenty-four compounds were identified as having either a delta 5, delta 7, or delta 0 nucleus. Two of them, the rare 20-methylpregn-5-en-3 beta-ol and 20-ethylpregn-5-en-3 beta-ol, were previously unreported as natural products from tunicates. These compounds were present only as trace components; therefore, their structures were confirmed by synthesis from suitable precursors and by comparison of the spectral and chromatographic constants of the synthetic and natural compounds.

Animals↗
PubMed1995

Fine specificity analysis indicates that the primary and secondary fluorescein-specific cytotoxic T cell receptor repertoires are indistinguishable.

Previous data from this laboratory have shown that fluorescein-specific cytotoxic T cells derived from naive mice are capable of distinguishing between different isomeric forms of the fluorescein hapten, as well as between the iodoacetamido-, isothiocyanate- and dichlorotriazinyl amino-fluorescein derivatives. In this report, we show that T cells derived from previously immunized animals, while demonstrating a stronger and more cross-reactive response overall, display identical fine specificity patterns to those of primary T cells for a panel of fluorescein homologues. We interpret this finding to indicate that the antigen receptor repertoires utilized by primary and secondary cytotoxic T cells are indistinguishable and that the enhanced response of memory as compared with naive CTL results from factors such as a higher density of cell surface receptors or receptor-associated molecules and/or a higher frequency of antigen-responsive T cells.

Animals↗
PubMed1995

Are elderly Asians in Britain at a high risk of vitamin D deficiency and osteomalacia?

Many studies have shown the indigenous elderly population and Asian immigrants to be groups at particular risk of vitamin D deficiency and osteomalacia, but there are no data on the risks in elderly Asians. In this community-based study a group of elderly Asians was compared with control groups of elderly and young whites and young Asians. Levels of 25-hydroxyvitamin D3 (25-OHD3) were significantly lower (p < 0.0001) in elderly Asians (21/37) and young Asians (7/17) compared with white controls. The difference in parathyroid hormone (PTH) between Asians and whites was also significant (p < 0.0007) as was that between young and old (p < 0.0002). Abnormal PTH and 25-OHD3 (high PTH and low 25-OHD3), indicative of a high risk of osteomalacia, occurred in 22% of elderly Asians compared with 6% of elderly whites. The calcium, phosphate and alkaline phosphatase were normal in all individuals. Among the Asians, vegetarianism was not related to lower 25-OHD3 levels. Symptoms suggestive of osteomalacia were more common (p < 0.05) in elderly Asians than in their white counterparts. This first study of 25-OHD3 levels in community-resident elderly Asians suggests that more than half were low, placing them at a significantly higher risk of osteomalacia.

Adult↗
PubMed1995

Hospitalizations for respiratory syncytial virus infection in Alaska Native children.

To characterize the epidemiology of Alaska Native children hospitalized for respiratory syncytial virus infections, we reviewed records of hospitalizations during the winter seasons of 1991 to 1992 and 1992 to 1993 at a hospital in Anchorage and a rural hospital in the Yukon Kuskokwim Delta (YKD) region of southwestern Alaska. The median age of hospitalization for respiratory syncytial virus infection was 2 months of age for YKD residents and 4.5 months for Anchorage residents. Sixteen percent of the hospitalized YKD children were less than 1 month of age, whereas the same was true for only 3% of the Anchorage children. Eight percent of the YKD patients required mechanical ventilation, whereas none of the Anchorage patients required ventilation. The median hospital stay was 4.8 days for YKD patients and 3.2 days for Anchorage patients. Hospitalization rates for infants less than 1 year of age were 33/1000 for Alaska Natives in Anchorage and 100/1000 for those in the YKD region. The extremely high hospitalization rate, especially among very young infants in the rural YKD region, points to a need for early preventive efforts.

Age Factors↗
PubMed1994

Computing for synchrotron radiation experiments.

Computing provision is of major concern to synchrotron radiation researchers. An overview is presented of the computing facilities for synchrotron radiation work at the Synchrotron Radiation Source, Daresbury Laboratory. Data acquisition, reduction and analysis are seen as an integrated activity essential for full utilization of beam time. We discuss the evolution of data-acquisition systems from stand-alone systems of limited computing power, to a unified project computing village using state-of-the-art equipment for combined-technique, high-data-rate experiments. A brief account of software packages for data reduction and analysis is also given.

Journal Article↗