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Biomedical subjects

Andrew Carr

Publications and source records attributed to Andrew Carr.

At least 19 recordsLinked to original sources
PubMed2007

Extreme context specificity in differential allelic expression.

Variability in cis-regulation of gene expression has been implicated in the phenotypic manifestation of complex traits including common, multifactorial diseases. The differential expression of alleles due to polymorphism in cis-regulatory elements is common in the human genome, but there is a paucity of information about the context specificity of these control elements. In this study, we examined the differential allelic expression (DAE) of BMP5 in human mesenchymal tissues obtained from 16 donors undergoing joint replacement for treatment of osteoarthritis. We observed significant differences in BMP5 allelic output, with allelic ratios greater than 4:1 (P < 10(-20)) in the tissues of some donors. We also discovered a significant variability in allelic expression within the different tissues of donors. For 12 of our donors, we examined the allelic expression of BMP5 in two different regions of cartilage: cartilage adjacent to the site of the osteoarthritic lesion and cartilage distal from the lesion. Five of these 12 donors demonstrated highly significant differences (P < or = 10(-8)) in allelic expression between the different regions of their cartilage. Using DAE as a phenotype, we attempted to map tissue-specific cis-regulatory polymorphisms, and we identified a single nucleotide polymorphism located downstream of BMP5, which was significantly associated with DAE in some but not all of the examined tissues. These findings suggest that allelic expression can be highly context specific and that when interrogating the cis-regulatory control of a particular gene, one cannot necessarily assume that allelic expression is conserved across different tissues or even across different regions of the same tissue.

Alleles↗
PubMed2007

Prevalence of metabolic syndrome in HIV-infected patients receiving highly active antiretroviral therapy using International Diabetes Foundation and Adult Treatment Panel III criteria: associations with insulin resistance, disturbed body fat compartmentalization, elevated C-reactive protein, and [corrected] hypoadiponectinemia.

OBJECTIVE: Metabolic syndrome is a cluster of risk factors for cardiovascular disease and type 2 diabetes. Definitions exist to identify those "at risk." Treatment of HIV infection with highly active antiretroviral therapy can induce severe metabolic complications including lipodystrophy, dyslipidemia, and insulin resistance. The purpose of this study was to report the prevalence of metabolic syndrome in HIV-infected patients and compare insulin resistance and total body, limb, and visceral fat and adipokines in those with and without metabolic syndrome. RESEARCH DESIGN AND METHODS: This was an international cross-sectional study of a well-characterized cohort of 788 HIV-infected adults recruited at 32 centers. Metabolic syndrome prevalence was examined using International Diabetes Federation (IDF) and U.S. National Cholesterol Education Program Adult Treatment Panel III (ATPIII) criteria, relative to body composition (whole-body dual-energy X-ray absorptiometry and abdominal computed tomography), lipids, glycemic parameters, insulin resistance, leptin, adiponectin, and C-reactive protein (CRP). RESULTS: The prevalence of metabolic syndrome was 14% (n = 114; 83 men) by IDF criteria and 18% (n = 139; 118 men) by ATPIII criteria; the concordance was significant but only moderate (kappa = 0.46, P < 0.0001). Many patients (49%) had at least two features of metabolic syndrome but were not classified as having metabolic syndrome as their waist circumferences or waist-to-hip ratios were in the non-metabolic syndrome range. Metabolic syndrome was more common in those currently receiving protease inhibitors (P = 0.04). Type 2 diabetes prevalence was five- to ninefold higher in those with metabolic syndrome. With IDF criteria, subjects with metabolic syndrome showed disturbances in inflammation and adipokines: they had higher CRP (5.5 +/- 7.0 vs. 3.9 +/- 6.0 mg/l, P < 0.003) and leptin (9 +/- 9 vs. 4 +/- 6 ng/ml, P < 0.0001) and lower adiponectin (12 +/- 8 vs. 15 +/- 10 microg/ml, P < 0.0001) levels. By ATPIII criteria, those with metabolic syndrome had higher leptin (6 +/- 8 ng/ml, P = 0.006) and lower adiponectin (15 +/- 10 vs. 18 +/- 8 microg/ml, P < 0.0001) levels. CONCLUSIONS: Metabolic syndrome prevalence in HIV-positive adults was lower than that reported for the general population. Metabolic syndrome was associated with a substantially increased prevalence of type 2 diabetes in this specific cohort. Many subjects without metabolic syndrome had at least two metabolic syndrome components (particularly elevated lipid levels) but did not meet waist circumference or waist-to-hip ratio cutoff metabolic syndrome criteria in this group with high rates of body fat partitioning disturbances.

Adiponectin↗
PubMed2006

Changes in body composition and mitochondrial nucleic acid content in patients switched from failed nucleoside analogue therapy to ritonavir-boosted indinavir and efavirenz.

BACKGROUND: Body composition changes complicate antiretroviral therapy. Improvements in lipoatrophy after a switch in nucleoside reverse-transcriptase inhibitors (NRTIs) have been demonstrated. We investigated 60 patients switching from failed NRTIs to ritonavir-boosted indinavir and efavirenz. METHODS: Body composition (assessed by dual-energy x-ray absorptiometry scan and by single-slice computed tomography of the abdomen through the level of the fourth lumbar vertebra [L4] and the mid-right thigh) and fasted metabolics were measured at the baseline time-point at switch and at weeks 48 and 96 thereafter. Mitochondrial DNA and RNA were extracted from right-thigh subcutaneous fat and peripheral-blood mononuclear cells (PBMCs) at weeks 0 and 48. The primary end point was the change in mean limb fat over 48 weeks. RESULTS: At week 96, we observed increases in mean (standard deviation [SD]) limb fat (+620 [974] g; P=.003), L4 subcutaneous adipose tissue (+20 [35] cm(2); P<.001), mid-thigh subcutaneous adipose tissue (+5 [10] cm(2); P<.001), and L4 visceral adipose tissue (+11 [34] cm(2); P=.01), but we also observed reduced lean limb mass (-831 [1,100] g; P=.3). Mean (SD) mtDNA content in subcutaneous fat and in PBMCs increased (+109 [274] and +45 [100] copies/cell, respectively). Improved virological control or immune recovery did not explain the results. Triglyceride, total cholesterol, estimated low-density lipoprotein cholesterol, ratio of total cholesterol to high-density lipoprotein cholesterol, and blood glucose levels deteriorated (i.e., had increased by 206%, 67%, 58%, 19%, and 6%, respectively, at week 96). CONCLUSIONS: This regimen was associated with statistically significant but clinically modest increases in peripheral fat, visceral fat, and mitochondrial nucleic acid content. A predominantly adverse metabolic profile developed.

Absorptiometry, Photon↗
PubMed2006

Pain and overall health status in older people with hip and knee replacement: a population perspective.

OBJECTIVE: To investigate the health-related quality of life and presence of hip or knee pain according to whether or not people had had previous hip or knee arthroplasty. STUDY DESIGN AND SETTING: Cross-sectional survey representing randomly selected sample of 5500 elderly (65+) people. Pain prevalence rates obtained from standard screening questions. Standard pain severity ratings obtained for each hip and knee. RESULTS: People with a past arthroplasty had worse health status compared to other people (p < 0.001 for all but two SF-36 dimensions). Hip or knee pain was more prevalent amongst people with past hip or knee replacement than amongst those without (62.5% versus 36.5% respectively; following adjustment for age and sex: Mantel-Haenszel combined odds ratio = 2.90, 95% CI 2.30-3.68, p < 0.001). More replaced knee joints were symptomatic than replaced hip joints (OR = 1.62, p = 0.022). CONCLUSIONS: Elderly people with a past hip or knee arthroplasty have significantly greater health and social care needs than other people--especially those related to pain and mobility. This may reflect the generalised nature of the underlying disease process.

Aged↗
PubMed2006

Effect of pravastatin on body composition and markers of cardiovascular disease in HIV-infected men--a randomized, placebo-controlled study.

OBJECTIVES: To determine the effect of the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, pravastatin, on markers of cardiovascular risk and lipodystrophy in HIV-infected, protease inhibitor (PI)-treated men with hypercholesterolaemia. METHODS: A randomized, placebo-controlled, 16-week study was carried out on 33 HIV-infected, hypercholesterolaemic men (fasting total cholesterol > 6.5 mmol/L) on PI-containing therapy. Patients commenced dietary assessment and advice at week 0 and were randomized to 12 weeks pravastatin (40 mg each night) or placebo from week 4. The primary endpoint was the time-weighted change (TWAUC) in total cholesterol from week 0. Secondary endpoints included TWAUC cholesterol from week 4 (start of pravastatin), total and regional body fat, fasting lipids, glucose, insulin, and markers of cardiovascular risk. RESULTS: Of 33 men randomized (pravastatin n = 16, mean age 48 years), 31 completed the study. Groups were matched for baseline cholesterol and body composition. Although there was no significant between-group difference in TWAUC cholesterol from week 0 (pravastatin -0.6 +/- 1.0 versus placebo -0.4 +/- 1.0 mmol/L/week; P = 0.8), TWAUC cholesterol from week 4 decreased more in the pravastatin group (-0.8 +/- 1.0 versus -0.3 +/- 0.9 mmol/L/week; P = 0.04). Neither triglycerides nor dietary intake changed. Subcutaneous fat increased significantly with pravastatin (+0.72 +/- 1.55 versus +0.19 +/- 0.48 kg change in limb fat, P < 0.04; +5.2 +/- 8.7 versus -1.3 +/- 13.7 cm change in abdominal subcutaneous fat, P = 0.02). Apart from homocystine, which decreased in the pravastatin group, there were no significant differences in other cardiovascular, lipid or glucose parameters. CONCLUSIONS: Despite limited effects on cholesterol, 12 weeks use of pravastatin 40 mg each night in HIV-infected men with hypercholesterolaemia resulted in significant increases in subcutaneous fat.

Adipose Tissue↗
PubMed2006

Inferring parrotfish (Teleostei: Scaridae) pharyngeal mill function from dental morphology, wear, and microstructure.

Morphology, occlusal surface topography, macrowear, and microwear features of parrotfish pharyngeal teeth were investigated to relate microstructural characteristics to the function of the pharyngeal mill using scanning electron microscopy of whole and sectioned pharyngeal jaws and teeth. Pharyngeal tooth migration is anterior in the lower jaw (fifth ceratobranchial) and posterior in the upper jaw (paired third pharyngobranchials), making the interaction of occlusal surfaces and wear-generating forces complex. The extent of wear can be used to define three regions through which teeth migrate: a region containing newly erupted teeth showing little or no wear; a midregion in which the apical enameloid is swiftly worn; and a region containing teeth with only basal enameloid remaining, which shows low to moderate wear. The shape of the occlusal surface alters as the teeth progress along the pharyngeal jaw, generating conditions that appear suited to the reduction of coral particles. It is likely that the interaction between these particles and algal cells during the process of the rendering of the former is responsible for the rupture of the latter, with the consequent liberation of cell contents from which parrotfish obtain their nutrients.

Animals↗
PubMed2006

The role of hydroxyurea in enhancing the virologic control achieved through structured treatment interruption in primary HIV infection: final results from a randomized clinical trial (Pulse).

BACKGROUND: Structured treatment interruptions (STIs) have been postulated to improve virologic control in primary HIV infection (PHI) by stimulating HIV-specific T-lymphocyte immunity. The addition of hydroxyurea (HU) may reduce viral production from activated CD4 cells. METHODS: Patients with PHI received a standardized antiretroviral (ARV) regimen consisting of indinavir 800 mg twice daily (BID), ritonavir 100 mg BID, didanosine 400 mg (QD), and either stavudine 40 mg BID or lamivudine 150 mg BID, for up to 12 months and were randomized to HU 500 mg BID or not. If viral suppression (<50 copies/mL) was achieved, up to 3 STIs were undertaken. Two ARV cycles were allowed after each interruption if virologic rebound to more than 5000 RNA copies/mL occurred. Treatment success was defined as maintaining viral loads below 5000 copies/mL for 6 months after ARV interruption. RESULTS: Sixty-eight male homosexual patients were randomized: 35 to ARV + HU and 33 to ARV-alone. Median baseline HIV RNA was 5.73 log10 copies/mL, and median CD4 T-lymphocyte count was 517 cells/microL. Treatment success was not significantly different between those receiving and not receiving HU, with 9 (26%) and 9 (27%), respectively, maintaining viral load at less than 5000 copies/mL in each group (P = 0.88). Virologic control was achieved by 11 (19%) of 59 after 1 STI, 1 (2%) of 41 after 2 STIs, and 6 (17%) of 36 after the third STI. Serious adverse events were recorded for 9 (26%) of 35 of patients using HU and 3 (9%) of 33 in the ARV-only group (P = 0.28). CD4 cell increases were significantly blunted for the HU group compared to the ARV-alone group after the initial treatment phase (+101 cells vs. +196 cells, respectively, P = 0.006). CONCLUSIONS: Hydroxyurea was not found to be beneficial when used in association with STIs in patients during PHI.

Adult↗
PubMed2006

Evaluation of the HIV lipodystrophy case definition in a placebo-controlled, 144-week study in antiretroviral-naive adults.

OBJECTIVE: To compare three versions of the objective HIV-associated lipodystrophy (HIVLD) case definition (LDCD) and derived severity scale to spontaneous clinical LD assessment in adults initiating antiretroviral therapy. DESIGN AND MAIN OUTCOME MEASURES: The LDCD versions were the 'primary' LDCD [which includes dual-energy X-ray absorptiometry (DXA) and computerized tomography (CT)], a simpler 'central' LDCD that omits CT data, and a simpler but probably less accurate 'non-imaging' LDCD. Physician LD assessments were passively reported. Two of the 10 parameters in the primary LDCD were not collected and were imputed. Setting, participants and interventions: Retrospective analysis of a randomized, placebo-controlled, 144-week study of tenofovir DF or stavudine (d4T) in 600 antiretroviral-naive adults. RESULTS: Central LDCD and clinical assessment diagnosed LD in 27% and 19% of d4T recipients at week 144, respectively (P < 0.001), and 3% and 3% of tenofovir DF recipients, respectively (P = 0.248). The central LDCD performed at least as well as the primary LDCD; both were more sensitive than the non-imaging model. There was poor concordance between clinical and LDCD-based diagnosis (kappa 0.02-0.20); most clinical cases did not fulfill any LDCD. Using the central LDCD, most LD was grade 1; 6% of d4T recipients and no tenofovir DF recipient had grade 3-4 LD at week 144 (P = 0.007). Independent risk factors for LD using the central LDCD were d4T, increasing age, female sex and higher baseline triglycerides, whereas clinical assessment consistently identified only d4T. The LDCD score was more sensitive than DXA for assessing LD severity. CONCLUSIONS: In this prospective study of a first antiretroviral regimen, the LDCD was more sensitive for LD diagnosis and identified more lipodystrophy risk factors than spontaneous clinical assessment or DXA, and also objectively quantified LD severity. The central LDCD should make objective LD assessment cheaper and simpler. Spontaneous clinical LD assessment of is of limited value, even in placebo-controlled trials.

Absorptiometry, Photon↗
PubMed2005

A response to issues raised in a recent paper concerning the Oxford knee score.

In a recently published paper, authors were critical of the Oxford Knee Score (OKS) patient based measure. We discuss a number of the interesting issues that this paper raised and point out some obvious misunderstandings. The OKS, whilst not perfect, has been shown in independent comparative studies to perform more satisfactorily than other measures. It remains one of a small number of measures with satisfactory measurement properties. It would be a great pity if clinicians were deterred from using the OKS on the basis of comments made in the recent publication.

Aged↗
PubMed2005

Dating of multistage fluid flow in sandstones.

Through ultraviolet laser argon-argon dating of potassium feldspar cements containing fluid inclusions, we determined temperature-composition-time data for paleofluids in a sedimentary basin, including data for an evolving episode of fluid flow recorded in distinct phases of cement. The fluid evolved from mixed aqueous oil 83 million years ago to purely aqueous by 76 million years ago, thus dating the time of oil charge in this reservoir.

Journal Article↗
PubMed2005

Evaluation of ultrasound for assessing facial lipoatrophy in a randomized, placebo-controlled trial.

We investigated the utility of ultrasonography for assessing facial lipoatrophy changes in HIV-infected adults receiving antiretroviral therapy who participated in a 48-week, randomized, placebo-controlled trial of rosiglitazone. Ultrasound was performed at weeks 0, 24 and 48 to determine the subcutaneous fat thickness over the malar bone. Changes in facial fat assessed by ultrasonography did not correlate significantly with more established objective measures of lipoatrophy severity. The measurement of malar fat using ultrasonography is not recommended.

Anti-HIV Agents↗
PubMed2005

Evidence for reduced B-cell progenitors in early (low-risk) myelodysplastic syndrome.

Early, low-risk International Prognostic Scoring System (IPSS) myelodysplastic syndrome (MDS) is a heterogeneous disorder where the molecular and cellular hematopoietic defects are poorly understood. To gain insight into this condition, we analyzed gene expression profiles of marrow CD34+ progenitor cells from normal-karyotype, low-blast-count MDS patients, age-matched controls, and patients with non-MDS anemia. Given the heterogeneity of early MDS, a surprisingly consistent finding was decreased expression of B-cell lineage-affiliated genes in MDS patients compared with healthy controls and 3 of 5 samples with non-MDS anemia. Both patients with non-MDS anemia with reduced B-cell gene expression were on chemotherapy. In 25 of 27 of the original samples and 9 further MDS samples, Taqman real-time polymerase chain reaction (PCR) confirmed these data. Flow cytometry on unfractionated marrow from independent samples also demonstrated reduced B-cell progenitors in MDS patients compared with healthy controls. These novel findings suggest a common perturbation in early MDS hematopoiesis. They also provide the rationale for a larger study to evaluate the diagnostic utility of reduced B-cell progenitor number as a diagnostic biomarker of early low-risk MDS, which can pose a diagnostic challenge.

Adult↗
PubMed2005

Atazanavir trough plasma concentration monitoring in a cohort of HIV-1-positive individuals receiving highly active antiretroviral therapy.

OBJECTIVES: Atazanavir is a recently approved HIV protease inhibitor (PI). As with other PIs, careful attention to potential pharmacokinetic drug interactions in clinical practice is necessary. The aim of this study was to assess the clinical associations with plasma atazanavir concentrations in HIV-positive individuals. METHODS: Individuals established on an atazanavir-containing regimen, completed an interviewer-administered questionnaire recording atazanavir dosing characteristics, concomitant medication use and adherence. After completion, plasma atazanavir concentrations were measured. RESULTS: Of 100 individuals, mean trough plasma atazanavir concentrations (mug/L) were 282 (95% CI 95-468, n = 19) and 774 (95% CI 646-902, n = 81) in those on non- and ritonavir-boosted atazanavir regimens, respectively. Eighty-five individuals had HIV RNA <50 copies/mL. Seven individuals had atazanavir plasma concentrations below the assay limit of detection (<50 microg/L), all of whom had undetectable plasma HIV RNA. In a multivariate analysis, nevirapine use was associated with significantly lower trough atazanavir concentrations (P = 0.011) and lopinavir/ritonavir use with higher trough atazanavir concentrations (P = 0.032). Dosing characteristics (including food taken), concomitant medications (including drugs used for dyspepsia) and HIV RNA were not significantly associated with trough atazanavir concentrations. CONCLUSIONS: In this cohort, despite the wide inter-individual variability of atazanavir trough concentrations, no significant association with dosing characteristics, concomitant medication (with the exception of nevirapine and lopinavir/ritonavir) or virological response was observed. Further work is needed to assess the optimal dosing regimen when using atazanavir with nevirapine.

Anti-HIV Agents↗
PubMed2005

Impact of persistent hip or knee pain on overall health status in elderly people: a longitudinal population study.

OBJECTIVE: To investigate hip or knee symptoms in older persons from a longitudinal, population perspective, and to determine the impact of persistent hip or knee pain on general health status over time. METHODS: A postal questionnaire was sent to a random sample of 5,500 individuals ages > or = 65 years containing the Short Form 36 (SF-36) general health survey, Lequesne hip and knee indices, and a hip/knee pain severity item. Respondents reporting hip or knee symptoms at baseline received an identical questionnaire 12 months later. Respondents were classified into a persistent pain group with either hip or knee pain at both baseline and followup, and a non-persistent pain group who reported hip or knee pain at baseline but no pain at followup. RESULTS: At baseline, 1,305 (40.7%) of 3,210 eligible respondents reported hip or knee pain. At 1 year, 1,072 (82.1%) of 1,305 individuals responded, of whom 820 (76.5%) remained symptomatic (the persistent group). In multivariate analysis, baseline factors identified as strongly related to having persistent pain were maximum Lequesne score (odds ratio [OR] 1.09, P < 0.001), maximum hip/knee pain score (OR 1.61, P < 0.001), and number of painful hip and knee joints at baseline (OR 1.48, P = 0.004). Following adjustment for age, sex, and baseline score, differences in mean SF-36 change scores of the 2 groups were significant for all dimensions except for mental health. CONCLUSION: In older persons, a symptomatic hip or knee frequently progresses in terms of worsening symptoms and accrual of other symptomatic hip or knee joints. The impact of persistent symptoms on general health is substantial.

Aged↗