True cadence and step accumulation are not equivalent: the effect of intermittent claudication on free-living cadence.

'True cadence' is the rate of stepping during the period of stepping. 'Step accumulation' is the steps within an epoch of time (e.g. 1min). These terms have been used interchangeably in the literature. These outcomes are compared within a population with intermittent claudication (IC). Multiday, 24h stepping activity of those with IC (30) and controls (30) was measured objectively using the activPAL physical activity monitor. 'True cadence' and 'step accumulation' outcomes were calculated. Those with IC took fewer steps/d 6531±2712 than controls 8692±2945 (P=0.003). However, these steps were taken within approximately the same number of minute epochs (IC 301±100min/d; controls 300±70min/d, P=0.894) with only slightly lower true cadence (IC 69 (IQ 66,72) steps/min; controls 72 (IQ 68,76) steps/min, P=0.026), giving substantially lower step accumulation (IC 22 (IQ 19,24) steps/min; controls 30 (IQ 23,34) steps/min) (P<0.001). However, the true cadence of stepping within the blocks of the 1, 5, 20, 30 and 60min with the maximum number of steps accumulated was lower for those with IC than controls (P<0.05). Those with IC took 1300 steps fewer per day above a true cadence of 90 steps/min. True cadence and step accumulation outcomes were radically different for the outcomes examined. 'True cadence' and 'step accumulation' were not equivalent in those with IC or controls. The measurement of true cadence in the population of people with IC provides information about their stepping rate during the time they are stepping. True cadence should be used to correctly describe the rate of stepping as performed.

Late effects of a brief psychological intervention in patients with intermittent claudication in a randomized clinical trial.

BACKGROUND: The authors previously reported the early results of a trial of a brief psychological intervention to increase physical activity in patients with intermittent claudication. After 4 months, participants in the intervention group walked a mean of 1576 more steps per day than control group participants. The present study followed the original participants to determine whether this behaviour change was maintained over 2 years. METHODS: This was a randomized single-centre parallel-group trial. Fifty-eight patients newly diagnosed with intermittent claudication were assigned randomly to one of two groups. The control group (30 patients) received usual care: lifestyle advice and consultation with a vascular surgeon to agree a treatment plan. The treatment group (28) received usual care plus a brief psychological intervention designed to modify illness and walking beliefs, and develop a personalized walking action plan. The primary outcome was daily steps measured by pedometer. Secondary outcomes included revascularization rate, quality of life and perceived pain-free walking distance. Follow-up was conducted at 1 and 2 years. Between-group differences were analysed by analysis of co-variance. RESULTS: Participants in the brief psychological intervention group walked significantly more than those in the control group. The mean difference at 1 year was 1374 (95 per cent confidence interval 528 to 2220) steps per day and the difference at 2 years was 1630 (495 to 2765) steps per day. CONCLUSION: Modifying illness and walking beliefs, and assisting patients to develop a personalized walking action plan led to increases in walking behaviour in patients with claudication that were maintained for 2 years. REGISTRATION NUMBER: ISRCTN28051878 (http://www.controlled-trials.com).

A multicentre observational study of the outcomes of screening detected sub-aneurysmal aortic dilatation.

OBJECTIVES: Currently most abdominal aortic aneurysm screening programmes discharge patients with aortic diameter of less than 30 mm. However, sub-aneurysmal aortic dilatation (25 mm-29 mm) does not represent a normal aortic diameter. This observational study aimed to determine the outcomes of patients with screening detected sub aneurysmal aortic dilatation. DESIGN AND METHODS: Individual patient data was obtained from 8 screening programmes that had performed long term follow up of patients with sub aneurysmal aortic dilatation. Outcome measures recorded were the progression to true aneurysmal dilatation (aortic diameter 30 mm or greater), progression to size threshold for surgical intervention (55 mm) and aneurysm rupture. RESULTS: Aortic measurements for 1696 men and women (median age 66 years at initial scan) with sub-aneurysmal aortae were obtained, median period of follow up was 4.0 years (range 0.1-19.0 years). Following Kaplan Meier and life table analysis 67.7% of patients with 5 complete years of surveillance reached an aortic diameter of 30 mm or greater however 0.9% had an aortic diameter of 54 mm. A total of 26.2% of patients with 10 complete years of follow up had an AAA of greater that 54 mm. CONCLUSION: Patients with sub-aneurysmal aortic dilatation are likely to progress and develop an AAA, although few will rupture or require surgical intervention.

Free-living physical activity as a novel outcome measure in patients with intermittent claudication.

OBJECTIVE: To develop a method of event-based analysis that quantifies the fragmented nature of walking bouts in individuals with intermittent claudication [IC] and compare outcomes with age and gender-matched healthy controls. DESIGN: Cross-sectional. MATERIALS: The activPAL™ physical activity monitor. METHODS: 7-day physical activity patterns were compared between individuals with IC (n = 30) and controls matched for age and gender (n = 30). The ratio of the number of walking events to upright events was calculated to provide an event-based claudication index (EBCI) that represented the fragmented nature of walking bouts commonly reported in those with IC. RESULTS: Individuals with IC had a greater EBCI than age matched controls indicating a more fragmented walking pattern (5.8 ± 2.0 vs. 7.7 ± 3.1, p < 0.01). The difference between groups was more pronounced when the EBCI was calculated from upright events that included >400 steps (23.4 ± 11.3 vs. 35.8 ± 14.2, p < 0.01). CONCLUSION: The classic fragmented stop/start walking pattern universally described by individuals with IC can be quantified using the EBCI. This method of measurement potentially provides a novel method of assessing the effectiveness of clinical interventions for this patient group.

Randomized clinical trial of a brief psychological intervention to increase walking in patients with intermittent claudication.

BACKGROUND: Increased walking is often recommended for patients with intermittent claudication (IC). Current methods to increase walking in these patients increase capability but not daily behaviour. This trial assessed whether a brief psychological intervention could increase daily walking at 4 months. METHODS: This randomized, single-centre, parallel-group trial was conducted between April 2008 and July 2010. Patients newly diagnosed with IC were randomly assigned into two groups. All clinical staff involved in patient management were blinded to allocation. The control group received usual care plus researcher contact, and the treatment group received usual care and a brief psychological intervention to modify illness and walking beliefs and to develop a personalized walking action plan. The psychological intervention was delivered in two 1-h sessions in participants' homes. The primary outcome was daily steps measured by pedometer 4 months later. Analyses were by intention to treat. RESULTS: Of 109 patients screened, 72 were eligible for inclusion; 58 patients consented to participate and were randomly allocated to usual care (30) or brief psychological intervention (28). All 58 participants were included in the analysis of the primary outcome. Compared with controls at 4-month follow-up, participants who received the psychological intervention walked a mean of 1575·63 (95 per cent confidence interval 731·97 to 2419·29) more steps per day. There were no adverse events. CONCLUSION: A brief psychological intervention significantly increased daily walking in patients with IC at 4 months. This study provided support for a potentially new direction in the treatment of IC. REGISTRATION NUMBER: ISRCTN28051878 (http://www.controlled-trials.com).

Rapid screening for the detection of HLA-B57 and HLA-B58 in prevention of drug hypersensitivity.

HLA-B57 and HLA-B58 are major histocompatibility class (MHC)-I allotypes that are potentially predictive of important clinical immune phenotypes. HLA-B*5701 is strongly associated with hypersensitivity to the HIV drug abacavir, liver toxicity from the antibiotic flucloxacillin and is a marker for slow progression of HIV AIDS. HLA-B*5801 is associated with hypersensitivity to allopurinol used to treat hyperuricaemia and recurrent gout. Here we describe a monoclonal antibody (mAb) specific for HLA-B57 and HLA-B58 that provides an inexpensive and sensitive screen for these MHC-I allotypes. The usefulness of HLA-B57 screening for prediction of abacavir hypersensitivity was shown in three independent laboratories, including confirmation of the mAb sensitivity and specificity in a cohort of patients enrolled in the PREDICT-1 trial. Our data show that patients who test negative by mAb screening comprise 90%-95% of all individuals in most human populations and require no further human leukocyte antigen (HLA) typing. Patients who test positive by mAb screening should proceed to high-resolution typing to ascertain the presence of HLA-B*5701 or HLA-B*5801. Hence, mAb screening provides a low-cost alternative to high-resolution typing of all patients and lends itself to point-of-care diagnostics and rapid ascertainment of low-risk patients who can begin immediate therapy with abacavir, flucloxacillin or allopurinol.

Virtual crossmatch approach to maximize matching in paired kidney donation.

We developed and tested a new computer program to match maximal sets of incompatible live donor/recipient pairs from a national paired kidney donation (PKD) registry. Data of 32 incompatible pairs included ABO and 4 digit-high-resolution donor and recipient HLA antigens and recipient's HLA antibodies. Three test runs were compared, in which donors were excluded from matching to recipients with either donor-specific antibodies (DSA) >8000MFI (mean fluorescent intensity) at low-resolution (Run 1) or >8000MFI at high-resolution (Run 2) or >2000MFI and high-resolution (Run 3). Run 1 identified 22 703 possible combinations, with 20 pairs in the top ranked, Run 2 identified 24 113 combinations, with 19 pairs in the top ranked and Run 3 identified 8843 combinations, with 17 pairs in the top ranked. Review of DSA in Run 1 revealed that six recipients had DSA 2000-8000MFI causing a possible positive crossmatch resulting in breakdown of two 3-way and three 2-way chains. In Run 2, four recipients had DSA 2000-8000MFI, also potentially causing breakdown of three 2-way chains. The more prudent approach of excluding from matching recipients with DSA with >2000MFI reduces the probability of matched pairs having a positive crossmatch without significantly decreasing the number of possible transplants.

Solid phase HLA antibody detection technology--challenges in interpretation.

The introduction into routine diagnostic laboratories of solid phase assays for human leukocyte antigen (HLA) antibody detection has resulted in the application of new laboratory matching algorithms in clinical organ transplantation which have improved pre-transplant detection of immunization, in turn resulting in avoidance of rejection in many cases which until their introduction would not have been possible using the historical complement dependent serological techniques. There have been two generations of solid phase assays introduced into routine practice, namely, the enzyme-linked immunosorbent assay (ELISA) technique and the use of fluorescent beads with HLA molecules bound to their surface which can either be used in conventional flow cytometry or in conjunction with Luminex instrumentation, the latter having become the most popular approach. The use of the fluorescent bead techniques has raised interesting questions both with respect to technical performance and the interpretation of the results obtained. The advantages of bead technology for HLA antibody determination and the technical issues requiring resolution are the subject of this review.

An update to HLA nomenclature, 2010.

The WHO Nomenclature Committee for Factors of the HLA System met during the 15th International Histocompatibility and Immunogenetics Workshop in Buzios, Brazil in September 2008. This update is an extract of the main report that documents the additions and revisions to the nomenclature of human leukocyte antigen (HLA) specificities following the principles established in previous reports.

The HLA dictionary 2008: a summary of HLA-A, -B, -C, -DRB1/3/4/5, and -DQB1 alleles and their association with serologically defined HLA-A, -B, -C, -DR, and -DQ antigens.

The 2008 report of the human leukocyte antigen (HLA) data dictionary presents serologic equivalents of HLA-A, -B, -C, -DRB1, -DRB3, -DRB4, -DRB5, and -DQB1 alleles. The dictionary is an update of the one published in 2004. The data summarize equivalents obtained by the World Health Organization Nomenclature Committee for Factors of the HLA System, the International Cell Exchange, UCLA, the National Marrow Donor Program, recent publications, and individual laboratories. The 2008 edition includes information on 832 new alleles (685 class I and 147 class II) and updated information on 766 previously listed alleles (577 class I and 189 class II). The tables list the alleles with remarks on the serologic patterns and the equivalents. The serological equivalents are listed as expert assigned types, and the data are useful for identifying potential stem cell donors who were typed by either serology or DNA-based methods. The tables with HLA equivalents are available as a searchable form on the IMGT/HLA database Web site (http://www.ebi.ac.uk/imgt/hla/dictionary.html).

Immunodominance hierarchies and gender bias in direct T(CD8)-cell alloreactivity.

Allogeneic solid organ transplantation often occurs across multiple donor-recipient HLA mismatches with consequent risk of allograft rejection. However, there is growing evidence that not all HLA mismatches are equivalent in their stimulation of allogeneic T cells making it important to determine which of these might be more significant as predictors of allograft rejection. To this end, we used defined antigen-presenting cell (APC) transfectants expressing single MHC-I allotypes as target cells that could discriminate the relative contribution of individual mismatched MHC-I allotypes to direct T-cell alloreactivity. We demonstrate remarkably reproducible patterns of immunodominance in reactivity across mismatched MHC-I allotypes. These patterns are HLA context-dependent, partly reflecting alloantigenic competition in responder cell responses. In strong alloresponses, we also observed an increased percentage of alloreactive T(CD8) cells in female responders, regardless of the stimulator gender, highlighting HLA-independent factors in the potency of the alloresponse. This approach provides a potential measure of specific alloreactive T cells that could be used in clinical practice for selection of donors, assessment of posttransplant outcomes, modulation of immunosuppression and detection of rejection episodes.

Ex vivo monitoring of human cytomegalovirus-specific CD8+ T-cell responses using QuantiFERON-CMV.

We have developed a novel diagnostic technology to monitor the human cytomegalovirus (HCMV)-specific CD8+ T-cell responses that is based on the detection of secreted interferon-gamma (IFN-gamma) in the whole blood (referred to as QuantiFERON -CMV). Evaluation of QuantiFERON -CMV in healthy individuals revealed that this technology was at least as sensitive and with some HCMV epitopes more sensitive than the ELISPOT for detecting ex vivo IFN-gamma. Results from QuantiFERON -CMV assays showed 97% (36/37 individuals) agreement with the anti-HCMV serology test in healthy individuals. Furthermore, we also show that this technology can be used to assess HCMV-specific T-cell responses in transplant patients. This study shows that QuantiFERON -CMV is a simple, reproducible, and reliable test for the detection of IFN-gamma in response to HCMV CD8+ T-cell epitopes, and may be a valuable diagnostic test for the detection of HCMV infection and a useful clinical tool for monitoring the immune response in immunosuppressed patients during therapy.

Improving communication among the HLA typing laboratories, transplant centers, and coordinating center.

Good communication between the bone marrow registries, the donor centres, tissue typing laboratories and clinical units is paramount to ensure timely identification, testing and selection of donors for unrelated bone marrow transplants. This panel session focussed on how to improve communication so that there was a clear understanding of prioritization of requests from clinicians, typing strategies in the laboratories and requests for donors to the registries. This paper outlined some of the strategies discussed in this session.

Donor methylenetetrahydrofolate reductase genotype is associated with graft-versus-host disease in hematopoietic stem cell transplant patients treated with methotrexate.

Methotrexate (MTX), used as a graft-versus-host disease (GvHD) prophylactic agent in hematopoietic stem cell transplantation (HSCT), exerts its effect via folate cycle inhibition. A critical enzyme involved in folate metabolism is 5,10-methylenetetrahydrofolate reductase (MTHFR). We examined the association of a single nucleotide polymorphism (SNP) at position 677 in the MTHFR gene on GvHD outcomes in allogeneic HSCT patients administered MTX. MTHFR genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) on 193 HSCT patients and donors. A total of 140 patients were transplanted with an HLA-matched related donor and 53 with an unrelated donor. GvHD outcomes were compared between genotypes by univariate and multivariate analysis. The combined donor 677CT and TT genotypes were associated with a decreased incidence of GvHD (acute and chronic combined) in HSCT recipients with an HLA-matched related donor (75% at 1 year in the CT and TT group compared with 91% in the wild type CC group, P=0.01), increased time to onset of first GvHD (P=0.001) and time to first GvHD treated with systemic therapy (P=0.022). Unrelated donor MTHFR genotype was not associated with outcome parameters and no associations of recipient genotype in either related or unrelated donor cohorts were observed.

Near-infrared tunable diode laser spectrometer for the remote sensing of vehicle emissions.

A near-infrared diode laser-based spectrometer has been designed and built for the remote sensing of vehicle emissions. It detects carbon monoxide and carbon dioxide absorptions around 1580 nm and can provide the ratio CO/CO(2) for vehicle exhaust studies. The system is battery powered and is designed to sit unobtrusively at the side of the road. The optics and electronics of the system is described and preliminary results are presented from field trials. Extensions to the spectrometer in terms of sensitivity by detection of the more intense first overtone of carbon monoxide around 2320 nm are described, in addition to further work on other species of interest.