The effect of age and sex on peak oxygen uptake during upper and lower body exercise: A systematic review

BACKGROUND

Large scale population norms for peak oxygen uptake (VO2peak) during cycle ergometry (CE) have been published for men and women across a wide range of ages. Although upper body functional capacity has an important role in activities of daily living far less is known regarding the effect of age and sex on upper body functional capacity (i.e. arm crank ergometry; ACE). The aim of this review was to determine the effect of age and sex on VO2peak obtained during ACE and CE in the same participants.

METHOD

The review was pre-registered with PROSEPERO (Ref: CRD42022349566). A database search using Academic Search Complete including CINAHL complete, CINHAL Ultimate, Medline, PubMed, SPORTDiscus was undertaken.

RESULTS

The initial search yielded 460 articles which was reduced to 243 articles following removal of duplicates. Twenty-five articles were subsequently excluded based on title resulting in 218 articles considered for retrieval. Following review of the abstracts, 78 further articles were excluded leaving 140 to be assessed for eligibility. Eighty-five articles were subsequently excluded, resulting in 55 articles being included. The decrease in VO2peak with age during CE was consistent with previous studies. Decreases in VO2peak during ACE with age, although paralleling those of CE, appeared to be of greater functional importance. When changes in VO2peak were considered below the age of 50 years little change was observed for absolute VO2peak during ACE and CE. In contrast, relative VO2peak demonstrated decreases in VO2peak for both ACE and CE likely reflecting increases in body mass and body fat percentage with age. After 50 years of age absolute and relative VO2peak demonstrated more similar and subtle responses. Heterogeneity across studies for both absolute and relative VO2peak between ACE and CE was large. Although strict inclusion criteria were applied, the inter-individual variation in sample populations was likely the main source of heterogeneity. There was a considerable lack data sets available for ages above 40 years of age.

CONCLUSIONS

These responses suggest that upper body VO2peak decreases in line with that of the lower body but, due to the lower peak values achieved during ACE, decreases in VO2peak may have more profound functional impact compared to that for the lower body. Using absolute and relative measures of VO2peak results in different age-related profiles when considered below 50 years of age. To further our understanding of whole body ageing more data is required for participants in mid and later life. The association between VO2peak and underlying physiological factors with age needs to be studied further, particularly in conjunction with activities of daily living and independent living.

O-009 Controlled ovarian stimulation (COS) protocols for assisted reproduction: a Cochrane systematic review and network meta-analysis

Study question

What is the relative effectiveness and safety of existing COS protocols for women undergoing assisted reproductive technology (ART) treatment?

Summary answer

There was no difference in live birth between all protocols, but short antagonist protocols may reduce ovarian hyperstimulation syndrome in women with predicted normal/high response.

What is known already

Controlled ovarian stimulation is an essential step in most ART cycles. It involves the administration of exogenous gonadotrophins to induce multifollicular growth, usually in addition to drugs that prevent untimely ovulation by suppressing the pituitary gland. Different treatment combinations may be used in COS. These vary according to the type of drugs administered for pituitary suppression (e.g., gonadotrophin-releasing hormone [GnRH] agonists, antagonists) and ovarian stimulation (e.g., urinary or recombinant gonadotrophins). Drug dosages, timing and routes of administration also vary between different regimens. However, there is no consensus on how the existing COS protocols rank according to their effectiveness and safety.

Study design, size, duration

We searched the following databases to November 2021: MEDLINE, EMBASE, CINAHL, CENTRAL and ClinicalTrials.gov. We included randomised controlled trials (RCTs) comparing at least two COS protocols using GnRH agonists or antagonists for pituitary suppression; and human menopausal gonadotrophin (hMG), urinary or recombinant follicle-stimulating hormone (u/rFSH), with or without luteinising hormone (LH) for ovarian stimulation. The primary outcomes were the rates of live birth (LBR) and ovarian hyperstimulation syndrome (OHSS) per participant after one stimulation cycle.

Participants/materials, setting, methods

Two reviewers independently selected studies and extracted data. We conducted pairwise and network meta-analyses (NMA) according to participants’ predicted response to COS (normal, high and low). Using the Cochrane-RoB-1 tool, we restricted our primary analyses to RCTs at low risk of selection and other biases. We presented effect estimates as risk ratio (RR) with 95% confidence interval (CI) and considered I2>50% as representing substantial heterogeneity. For each outcome, we generated ranking plots comparing different interventions.

Main results and the role of chance

In total, our searches identified 9464 studies. The primary analysis included 68 RCTs assessing 17861 women and 34 different COS protocols. The evidence showed that in women with predicted normal or high response, the use of short GnRH antagonist protocols may result in little to no difference in LBR (RR 0.98, 95% CI 0.85 to 1.13; 6 studies; 2063 women; I2 = 0%; low-certainty evidence) and a reduction in OHSS (RR 0.88, 95% CI 0.78 to 0.99; 7 studies; 2246 women; I2 = 0%; low-certainty evidence) compared with long GnRH agonist protocols. The rankogram comparing different COS protocols showed a probability of 98% that short GnRH antagonist regimens are the best treatment to prevent OHSS. Sensitivity analyses including all studies showed that in women with predicted normal response undergoing long GnRH agonist cycles for pituitary suppression, the use of rFSH for ovarian stimulation may result in decreased fresh-cycle LBR compared to hMG (RR 0.80, 95% CI 0.68 to 0.95; 7 studies; 1575 women; I2 = 1%; low-certainty evidence). For the remaining interventions (e.g., agonist flare or progestogens for pituitary suppression, in combination with various gonadotrophin regimens) the evidence was uncertain of an effect or insufficient for quantitative synthesis.

Limitations, reasons for caution

The high number of interventions resulted in disconnected networks, limiting our ability to perform NMA for some comparisons. The certainty of the evidence was limited by serious risk of bias. Finally, the lack of data on cumulative LBR and differences in oocyte yield made comparisons between FSH preparations potentially unbalanced.

Wider implications of the findings

Our findings suggest that the use of short GnRH antagonist protocols may result in reduced OHSS rates in women with predicted normal or high ovarian response without compromising live birth rates. There is a paucity of high-quality RCTs comparing different gonadotrophin preparations (e.g., hMG versus rFSH) for COS.

Trial registration number

N/A

H3K27me3 Demethylase UTX Restrains Plasma Cell Formation

B cell differentiation is associated with substantial transcriptional, metabolic, and epigenetic remodeling, including redistribution of histone 3 lysine 27 trimethylation (H3K27me3), which is associated with a repressive chromatin state and gene silencing. Although the role of the methyltransferase EZH2 (Enhancer of zeste homolog 2) in B cell fate decisions has been well established, it is not known whether H3K27me3 demethylation is equally important. In this study, we showed that simultaneous genetic deletion of the two H3K27 demethylases UTX and JMJD3 (double-knockout [Utx ^fl/fl Jmjd3 ^fl/fl Cd19 ^cre/+] [dKO]) led to a significant increase in plasma cell (PC) formation after stimulation with the T cell-independent Ags LPS and NP-Ficoll. This phenotype occurred in a UTX-dependent manner as UTX single-knockout mice, but not JMJD3 single-knockout mice, mimicked the dKO. Although UTX- and JMJD3-deficient marginal zone B cells showed increased proliferation, dKO follicular B cells also showed increased PC formation. PCs from dKO mice upregulated genes associated with oxidative phosphorylation and exhibited increased spare respiratory capacity. Mechanistically, deletion of Utx and Jmjd3 resulted in higher levels of H3K27me3 at proapoptotic genes and resulted in reduced apoptosis of dKO PCs in vivo. Furthermore, UTX regulated chromatin accessibility at regions containing ETS and IFN regulatory factor (IRF) transcription factor family motifs, including motifs of known repressors of PC fate. Taken together, these data demonstrate that the H3K27me3 demethylases restrain B cell differentiation.

An IRF4-MYC-mTORC1 Integrated Pathway Controls Cell Growth and the Proliferative Capacity of Activated B Cells during B Cell Differentiation In Vivo

Cell division is an essential component of B cell differentiation to Ab-secreting plasma cells, with critical reprogramming occurring during the initial stages of B cell activation. However, a complete understanding of the factors that coordinate early reprogramming events in vivo remain to be determined. In this study, we examined the initial reprogramming by IRF4 in activated B cells using an adoptive transfer system and mice with a B cell-specific deletion of IRF4. IRF4-deficient B cells responding to influenza, 4-hydroxy-3-nitrophenylacetyl-Ficoll, and LPS divided but stalled during the proliferative response. Gene expression profiling of IRF4-deficient B cells at discrete divisions revealed IRF4 was critical for inducing MYC target genes, oxidative phosphorylation, and glycolysis. Moreover, IRF4-deficient B cells maintained an inflammatory gene expression signature. Complementary chromatin accessibility analyses established a hierarchy of IRF4 activity and identified networks of dysregulated transcription factor families in IRF4-deficient B cells, including E-box binding bHLH family members. Indeed, B cells lacking IRF4 failed to fully induce Myc after stimulation and displayed aberrant cell cycle distribution. Furthermore, IRF4-deficient B cells showed reduced mTORC1 activity and failed to initiate the B cell activation unfolded protein response and grow in cell size. Myc overexpression in IRF4-deficient cells was sufficient to overcome the cell growth defect. Together, these data reveal an IRF4-MYC-mTORC1 relationship critical for controlling cell growth and the proliferative response during B cell differentiation.

Conserved Epigenetic Programming and Enhanced Heme Metabolism Drive Memory B Cell Reactivation

Memory B cells (MBCs) have enhanced capabilities to differentiate to plasma cells and generate a rapid burst of Abs upon secondary stimulation. To determine if MBCs harbor an epigenetic landscape that contributes to increased differentiation potential, we derived the chromatin accessibility and transcriptomes of influenza-specific IgM and IgG MBCs compared with naive cells. MBCs possessed an accessible chromatin architecture surrounding plasma cell-specific genes, as well as altered expression of transcription factors and genes encoding cell cycle, chemotaxis, and signal transduction processes. Intriguingly, this MBC signature was conserved between humans and mice. MBCs of both species possessed a heightened heme signature compared with naive cells. Differentiation in the presence of hemin enhanced oxidative phosphorylation metabolism and MBC differentiation into Ab-secreting plasma cells. Thus, these data define conserved MBC transcriptional and epigenetic signatures that include a central role for heme and multiple other pathways in augmenting MBC reactivation potential.

Antibody-secreting cell destiny emerges during the initial stages of B-cell activation

Upon stimulation, B cells assume heterogeneous cell fates, with only a fraction differentiating into antibody-secreting cells (ASC). Here we investigate B cell fate programming and heterogeneity during ASC differentiation using T cell-independent models. We find that maximal ASC induction requires at least eight cell divisions in vivo, with BLIMP-1 being required for differentiation at division eight. Single cell RNA-sequencing of activated B cells and construction of differentiation trajectories reveal an early cell fate bifurcation. The ASC-destined branch requires induction of IRF4, MYC-target genes, and oxidative phosphorylation, with the loss of CD62L expression serving as a potential early marker of ASC fate commitment. Meanwhile, the non-ASC branch expresses an inflammatory signature, and maintains B cell fate programming. Finally, ASC can be further subseted based on their differential responses to ER-stress, indicating multiple development branch points. Our data thus define the cell division kinetics of B cell differentiation in vivo, and identify the molecular trajectories of B cell fate and ASC formation.

Effect of age on the relative efficacy of clozapine in schizophrenia

OBJECTIVE

Early treatment of schizophrenia improves outcomes. Clozapine appears to have unique benefit when other antipsychotic medication has failed. This systematic review and meta-analysis aims to assess clozapine's superiority over alternative antipsychotic medication and examine whether earlier use is associated with additional benefit.

METHOD

Systematic retrieval of blinded, randomized controlled trials comparing clozapine with alternative antipsychotics in adults with schizophrenia. The effect of mean age on relative clozapine response was examined using random effects meta-regression, and multiple linear regression on available patient data.

RESULTS

A total of 276 studies were retrieved. Thirty-four studies were included in the meta-analysis. Clozapine was significantly more effective than alternative antipsychotics in reducing psychotic symptoms and increasing response. However, meta-regression failed to show a more significant effect in younger patients (age on effect size (total psychotic symptoms) 0.00, P = 0.79 CI -0.03 to 0.03). Individual patient data were available for two studies, the larger of which showed a significant interaction between younger age and superiority of clozapine.

CONCLUSION

The results support clozapine's superiority over other antipsychotics. A convincing effect of age on this effect was not demonstrated, although this was suggested in one study. In view of the age of many of the included studies, and changes in reporting practice over time, new clozapine RCTs, which include age of illness onset as well as age at trial time, would be welcome in order to provide meta-analysable data for future use.

Abstract A74: Loss of L-selectin distinguishes activated B cells destined to differentiate to plasma cells

Plasma cells engineered to produce and secrete de novo proteins have the potential to be used as biologic therapeutics for the treatment of cancer and other diseases. Genetic manipulation, expansion, and differentiation of naive B cells has been performed in vitro, and significant efforts have been made to understand and model the mechanisms that govern B cell fate decisions. Collectively, these studies indicated B-cell differentiation occurred across all cell divisions and that considerable cell fate heterogeneity exists between responding B cells within the same cell division. However, the differences in transcriptional programming that drive these differences and whether the same kinetics of cell division and differentiation are observed in vivo remain unknown, leaving a gap in our knowledge that may be critical for the efficacy of future therapeutic applications. To begin to address this, we employed an in vivo murine adoptive transfer system and monitored the kinetics of cell division and differentiation in response to lipopolysaccharide. We report that in vivo B cell differentiation requires a minimum of eight cell divisions, which corresponded to peak IRF4 expression and Blimp-1-mediated reprogramming. However, only a fraction of the cells that divided eight times differentiated, indicating that additional guidance cues ultimately decide cell fate decisions. To resolve B-cell differentiation at finer molecular resolution, we performed single-cell RNA sequencing. These data captured a continuum of LPS-responding B cells representing all stages of differentiation, with the majority of heterogeneity observed among activated B cells (actB). Computationally ordering cells along differentiation, or pseudotime, revealed divergent actB trajectories, with one branch leading to plasma cell formation that was dependent on IRF4. Cells along this branch upregulated genes associated with MYC activation and oxidative phosphorylation, both of which are important for achieving the metabolic and catabolic requirements to support plasma cell functions. Moreover, cells that followed this trajectory downregulated the surface marker L-selectin and could be separated from cells that followed the alternative non-plasma cell differentiation branch. Indeed, isolation of actB that had divided eight times and by L-selectin status confirmed that L-selectin-negative cells were ten times more likely to form plasma cells in culture. In summary, these data provide insight into the cell division kinetics of B-cell differentiation in vivo, highlight an IRF4-dependent bifurcation event that occurs early during actB reprogramming, and specify a strategy to identify actB that preferentially differentiate to plasma cells. Together, these data may be leveraged to improve desired immune outcomes by forcing cells down a path to a plasma cell or by identifying and expanding cells that are more prone to differentiate.

Citation Format: Dillon G. Patterson, Christopher D. Scharer, Tian Mi, Madeline J. Price, Sakeenah L. Hicks, Jeremy M. Boss. Loss of L-selectin distinguishes activated B cells destined to differentiate to plasma cells [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A74.

Progressive Upregulation of Oxidative Metabolism Facilitates Plasmablast Differentiation to a T-Independent Antigen

Transitioning from a metabolically quiescent naive B cell to an antibody-secreting plasmablast requires division-dependent cellular differentiation. Though cell division demands significant ATP and metabolites, the metabolic processes used for ATP synthesis during plasmablast formation are not well described. Here, the metabolic requirements for plasmablast formation were determined. Following T-independent stimulation with lipopolysaccharide, B cells increased expression of the oxidative phosphorylation machinery in a stepwise manner. Such activated B cells have increased capacity to perform oxidative phosphorylation but showed dependency on glycolysis. Plasmablasts displayed higher oxidative metabolism to support antibody secretion, as inhibiting oxidative ATP production resulted in decreased antibody titers. Differentiation by Blimp1 was required for this increase in oxidative metabolism, as Blimp1-deficient cells proliferate but do not upregulate oxidative phosphorylation. Together, these findings identify a shift in metabolic pathways as B cells differentiate, as well as the requirement for increased metabolic potential to support antibody production.

IgM, IgG, and IgA Influenza-Specific Plasma Cells Express Divergent Transcriptomes

Ab-secreting cells (ASC) or plasma cells are essential components of the humoral immune system. Although Abs of different isotypes have distinct functions, it is not known if the ASC that secrete each isotype are also distinct. ASC downregulate their surface BCR upon differentiation, hindering analyses that couple BCR information to other molecular characteristics. In this study, we developed a methodology using fixation, permeabilization, and intracellular staining coupled with cell sorting and reversal of the cross-links to allow RNA sequencing of isolated cell subsets. Using hemagglutinin and nucleoprotein Ag-specific B cell tetramers and intracellular staining for IgM, IgG, and IgA isotypes, we were able to derive and compare the gene expression programs of ASC subsets that were responding to the same Ags following influenza infection in mice. Intriguingly, whereas a shared ASC signature was identified, each ASC isotype-specific population expressed distinct transcriptional programs controlling cellular homing, metabolism, and potential effector functions. Additionally, we extracted and compared BCR clonotypes and found that each ASC isotype contained a unique, clonally related CDR3 repertoire. In summary, these data reveal specific complexities in the transcriptional programming of Ag-specific ASC populations.

Impact of glycaemic control on fracture risk in 5368 people with newly diagnosed Type 1 diabetes: a time-dependent analysis

AIMS

To assess whether glycaemic control is associated with a lifelong increased risk of fracture in people with newly diagnosed Type 1 diabetes.

METHODS

People with newly diagnosed Type 1 diabetes between 1 January 1995 and 10 May 2016 were identified in The Health Improvement Network database. Longitudinal HbA_1c measurements from diagnosis to fracture or study end or loss to follow-up were collected. A Cox proportional hazards model with HbA_1c included as a time-dependent variable was fitted to these data.

RESULTS

Some 5368 people with newly diagnosed Type 1 diabetes were included. The estimated adjusted hazard ratio (aHR) for HbA_1c was statistically significant [aHR 1.007; 95% confidence interval (CI) 1.002-1.011 (mmol/mol) and aHR 1.07; 95% CI 1.03-1.12 (%)]. An incremental higher risk of fracture was observed with increasing levels of HbA_1c .

CONCLUSIONS

In people with newly diagnosed Type 1 diabetes, higher HbA_1c is associated with an increased risk for fractures.

H3K27me3-specific demethylases modulate B cell development and differentiation

B cell terminal differentiation into antibody secreting plasma cells (ASC) must be properly regulated to ensure robust humoral immune responses against foreign but not self-antigens. While the role of transcription factors in this process is well-established, there is also a growing appreciation of the epigenetic regulation of B cell differentiation. The histone modification H3 lysine 27 trimethylation (H3K27me3) is associated with a repressive chromatin state and gene silencing and is highly dynamic during B cell differentiation. EZH2, the enzyme that deposits H3K27me3, is required for proper B cell development, as well as germinal center and ASC formation. However, the role of active demethylation of H3K27me3 by the two demethylases UTX and JMJD3 in B cells is still to be elucidated. To determine the requirements for these enzymes in B lymphocytes, we crossed Utxfl/flJmjd3fl/flmice onto Cd19Cre/+background (dKO mice). In dKO mice, we observed a significant increase in T2 transitional and marginal zone B cells in the spleen and a reduction in circulating mature B cells in the bone marrow. To determine the role of UTX and JMJD3 in T cell dependent B cell responses, we infected CreCtrl and dKO mice with PR8 influenza virus. Fourteen days post infection, we observed a modest increase in GC B cells and skewing in the GC polarity in dKO mice. RNA-seq of CreCtrl and dKO GC B cells revealed that majority of differentially expressed genes (DEGs) were downregulated in the absence of UTX and JMJD3. Furthermore, a subset of down-DEGs were enriched for H3K27me3 in dKO supporting the role of UTX and JMJD3 in promoting gene. expression. Taken together, these data place H3K27me3 demethylases as critical enzymes that regulate the epigenetic dynamics of B cell fate.

Epigenetic priming underpins enhanced memory B cell differentiation

Immunological memory is a hallmark of the adaptive immune response. Memory B cells (MBC) have increased affinity, expression of costimulatory molecules, and capacity to proliferate and differentiate than their naïve counterparts; however, the epigenetic mechanisms that control enhanced MBC functions are currently unknown. Using a murine model of influenza infection, nucleoprotein (NP)-specific MBC and follicular naïve B cells (nB) were isolated and the chromatin accessibility and transcriptional landscape determined by ATAC and RNA-seq, respectively. MBC displayed distinct gene expression profiles from nB, including an upregulation of plasma cell (PC) signature genes and significant overall increases in total mRNA content. Furthermore, MBC display an open and primed chromatin conformation in gene regulatory regions that map to transcription factors controlling either PC (Prdm1 and Irf4), germinal center (Aicda), or MBC (Zbtb32) fates. These data reveal additional novel MBC-specific transcription factor networks and describe an epigenetic “antigen experience” signature that correlates with enhanced MBC function. To confirm the importance of these molecular changes, naïve and memory mice were challenged with a heterosubtypic influenza infection or isolated and cultured with CD40L, IL-4, and IL-5. In vivo, MBC form germinal centers earlier and to a higher frequency than nB. MBC also form significantly more NP+IgG+ PCs by flow cytometry and ELISPOT, corroborating the open chromatin signature. Ex vivo, MBCs upregulated primed transcription factors earlier than nB, validating the enhanced formation of CD138+ PCs. These data describe an epigenetic basis for enhanced the differentiation capacity and function of MBC.

Gestational dyslipidaemia and adverse birthweight outcomes: a systematic review and meta-analysis

BACKGROUND

Low and high birthweight is known to increase the risk of acute and longer-term adverse outcomes, such as stillbirth, infant mortality, obesity, type 2 diabetes and cardiovascular diseases. Gestational dyslipidaemia is associated with a numbers of adverse birth outcomes, but evidence regarding birthweight is still inconsistent to reliably inform clinical practice and treatment recommendations.

OBJECTIVE

The aim of this study was to explore the relationship between maternal gestational dyslipidaemia and neonatal health outcomes, namely, birthweight, metabolic factors and inflammatory parameters.

METHODS

We searched systematically Embase, MEDLINE, PubMed, CINAHL Plus and Cochrane Library up to 1 August 2016 (with an updated search in MEDLINE at the end of July 2017) for longitudinal studies that assessed the association of maternal lipid levels during pregnancy with neonatal birthweight, or metabolic and inflammatory parameters up to 3 years old.

RESULTS

Data from 46 publications including 31,402 pregnancies suggest that maternal high triglycerides and low high-density-lipoprotein cholesterol levels throughout pregnancy are associated with increased birthweight, higher risk of large for gestational age and macrosomia and lower risk of small-for-gestational age. The findings were consistent across the studied populations, but stronger associations were observed in women who were overweight or obese prior to pregnancy.

CONCLUSIONS

This meta-analysis suggested that the potential under-recognized adverse effects of intrauterine exposure to maternal dyslipidaemia may warrant further investigation into the relationship between maternal dyslipidaemia and birthweight in large prospective cohorts or in randomized trials.

B cell activation and plasma cell differentiation are inhibited by de novo DNA methylation

B cells provide humoral immunity by differentiating into antibody-secreting plasma cells, a process that requires cellular division and is linked to DNA hypomethylation. Conversely, little is known about how de novo deposition of DNA methylation affects B cell fate and function. Here we show that genetic deletion of the de novo DNA methyltransferases Dnmt3a and Dnmt3b (Dnmt3-deficient) in mouse B cells results in normal B cell development and maturation, but increased cell activation and expansion of the germinal center B cell and plasma cell populations upon immunization. Gene expression is mostly unaltered in naive and germinal center B cells, but dysregulated in Dnmt3-deficient plasma cells. Differences in gene expression are proximal to Dnmt3-dependent DNA methylation and chromatin changes, both of which coincide with E2A and PU.1-IRF composite-binding motifs. Thus, de novo DNA methylation limits B cell activation, represses the plasma cell chromatin state, and regulates plasma cell differentiation.

Progressive upregulation of oxidative metabolism facilitates plasmablast differentiation to a T-independent antigen

Transitioning from a metabolically quiescent naïve B cell to an antibody-secreting plasmablast requires division-dependent cellular differentiation. Though cellular processes such as cell division and antibody secretion demand significant ATP and metabolites, the metabolic processes used to generate ATP during plasmablast formation are not well described. Here, the metabolic machinery requirements for plasmablast formation were determined. Following T-independent stimulation with lipopolysaccharide, B cells increased expression of the oxidative phosphorylation machinery in a step-wise manner. Such activated B cells have increased capacity to perform oxidative phosphorylation, but showed additional dependency on glycolytic metabolism. Plasmablasts displayed higher oxidative metabolism to support antibody secretion, as inhibiting oxidative ATP production with oligomycin resulted in decreased antibody titres. Differentiation orchestrated by Blimp1 was required for this increase in oxidative metabolism as Blimp1-deficient cells proliferate normally, but neither differentiate to plasmablasts nor upregulate oxidative phosphorylation. Therefore, Blimp1 expression is required for full metabolic activity, and proliferation alone is insufficient to induce full oxidative phosphorylation. Together, these findings identify a shift in metabolic pathways as B cells differentiate, as well as the requirement for increased metabolic potential to support antibody production.

Effects of external loads on postural sway during quiet stance in adults aged 20-80 years

The purpose of this study was to investigate the effects of holding external loads on postural sway during upright stance across age decades. Sixty-five healthy adults (females, n = 35), aged 18-80 years were assessed in four conditions; (1) standing without holding a load, holding a load corresponding to 5% body mass in the (2) left hand, (3) right hand and (4) both hands. The centre of pressure (COP) path length and anteroposterior and mediolateral COP displacement were used to indirectly assess postural sway. External loading elicited reductions in COP measures of postural sway in older age groups only (P < 0.05). No changes were observed in younger or intermediate aged adults (P > 0.05). Holding external loads during standing is relevant to many activities of daily living (i.e. holding groceries). The reduction in postural sway may suggest this type of loading has a stabilising effect during quiet standing among older adults.

EZH2 Represses the B Cell Transcriptional Program and Regulates Antibody-Secreting Cell Metabolism and Antibody Production

Epigenetic remodeling is required during B cell differentiation. However, little is known about the direct functions of epigenetic enzymes in Ab-secreting cells (ASC) in vivo. In this study, we examined ASC differentiation independent of T cell help and germinal center reactions using mice with inducible or B cell-specific deletions of Ezh2 Following stimulation with influenza virus or LPS, Ezh2-deficient ASC poorly proliferated and inappropriately maintained expression of inflammatory pathways, B cell-lineage transcription factors, and Blimp-1-repressed genes, leading to fewer and less functional ASC. In the absence of EZH2, genes that normally gained histone H3 lysine 27 trimethylation were dysregulated and exhibited increased chromatin accessibility. Furthermore, EZH2 was also required for maximal Ab secretion by ASC, in part due to reduced mitochondrial respiration, impaired glucose metabolism, and poor expression of the unfolded-protein response pathway. Together, these data demonstrate that EZH2 is essential in facilitating epigenetic changes that regulate ASC fate, function, and metabolism.

Oxidative phosphorylation is progressively programmed during plasma cell differentiation

The differentiation of immune cells requires a transition in metabolic programming to achieve effector function. Unlike T cells, the metabolic changes and epigenetic regulation of this process during the differentiation of antibody secreting plasma cells is not well characterized. Using in vivo and ex vivo LPS driven models of B cell differentiation, the metabolic changes and epigenetic regulation of metabolism was investigated. Naïve B cells (B220+GL7−CD138−) are metabolically quiescent, and upon activation through TLR4, B cells rapidly shift their metabolic program to use oxidative phosphorylation for their energetic demands. Activated B cells (B220+GL7+CD138−) use oxidative phosphorylation, but maintain a large spare respiratory capacity. In contrast, terminally differentiated, post-mitotic plasma cells (B220−GL7−CD138+) use oxidative phosphorylation at their maximal ability, with no spare respiratory capacity, suggesting unique metabolic changes are programmed upon differentiation. Next, an adoptive transfer model system that utilizes CFSE labeled B cells was used to distinguish molecular events during the proliferative/activation versus the differentiation phase. Analysis of epigenetic and transcriptome data in the two phases identified a subset of metabolic genes that underwent differentiation specific programming. Additionally, the role of key transcription factors was examined in terms of their control of the metabolic reprogramming steps. These results provide novel insights into how the step-wise changes in metabolism are programmed as quiescent B cells differentiate into antibody-secreting plasma cells.

Proportion of Tubal Factor Infertility due to Chlamydia: Finite Mixture Modeling of Serum Antibody Titers

In this study, we examined whether the proportion of tubal factor infertility (TFI) that is attributable to Chlamydia trachomatis, the population excess fraction (PEF), can be estimated from serological data using finite mixture modeling. Whole-cell inclusion immunofluorescence serum antibody titers were recorded among infertile women seen at St. Michael's Hospital in Bristol, United Kingdom, during the period 1985-1995. Women were classified as TFI cases or controls based on laparoscopic examination. Finite mixture models were used to identify the number of component titer distributions and the proportion of serum samples in each, from which estimates of PEF were derived. Four titer distributions were identified. The component at the highest titer was found only in samples from women with TFI, but there was also an excess of the second-highest titer component in TFI cases. Minimum and maximum estimates of the PEF were 28.0% (95% credible interval: 6.9, 50.0) and 46.8% (95% credible interval: 23.2, 64.1). Equivalent estimates based on the standard PEF formula from case-control studies were 0% and over 65%. Finite mixture modeling can be applied to serological data to obtain estimates of the proportion of reproductive damage attributable to C. trachomatis Further studies using modern assays in contemporary, representative populations should be undertaken.

Au-ACRAMTU-PEt3 Alters Redox Balance To Inhibit T Cell Proliferation and Function

Although T cells play a critical role in protection from viruses, bacteria, and tumors, they also cause autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis. Unwanted T cell responses during organ transplant, graft-versus-host disease, and allergies are also major clinical problems. Although drugs are available to suppress unwanted immune responses, they have limited efficacy with serious side effects. Thus, new therapeutics limiting T cell activation, proliferation, and function can make an immediate clinical impact. To identify new suppressors of lymphocyte activation, proliferation, and function, we examined the immunosuppressive activity of gold(I) analogs of platinum-acridine antitumor agents. We found that the gold complex Au-ACRAMTU-PEt3 is a potent suppressor of murine and human T cell activation. Preincubation with Au-ACRAMTU-PEt3 suppresses the proliferation of CD4(+) and CD8(+) T cells at a similar concentration as pharmaceutical grade cyclosporine A. Au-ACRAMTU-PEt3 pretreatment decreases the production of IFN-γ, TNF-α, IL-2, and IL-17 by human and murine CD4(+) and CD8(+) T cells. When mice were treated with Au-ACRAMTU-PEt3 during viral infection, the expansion of virus-specific CD8(+) T cells was decreased 10-fold and viral load was elevated. Taken together, these results demonstrate that Au-ACRAMTU-PEt3 has potent immunosuppressive activity that could be used to suppress immune responses during transplantation and autoimmunity.

The effects of arm crank ergometry, cycle ergometry and treadmill walking on postural sway in healthy older females

Older adults are increasingly being encouraged to exercise but this may lead to muscle fatigue, which can adversely affect postural stability. Few studies have investigated the effects of upper body exercise on postural sway in groups at risk of falling, such as the elderly. The purpose of this study was to compare the effects arm crank ergometry (ACE), cycle ergometry (CE) and treadmill walking (TM) on postural sway in healthy older females. In addition, this study sought to determine the time necessary to recover postural control after exercise. A total of nine healthy older females participated in this study. Participants stood on a force platform to assess postural sway which was measured by displacement of the centre of pressure before and after six separate exercise trials. Each participant completed three incremental exercise tests to 85% of individual's theoretical maximal heart rate (HRMAX) for ACE, CE and TM. Subsequent tests involved 20-min of ACE, CE and TM exercise at a relative workload corresponding to 50% of each individual's predetermined heart rate reserve (HRE). Post fatigue effects and postural control recovery were measured at different times after exercise (1, 3, 5, 10, 15 and 30-min). None of the participants exhibited impaired postural stability after ACE. In contrast, CE and TM elicited significant post exercise balance impairments, which lasted for ∼ 10 min post exercise. We provide evidence of an exercise mode which does not elicit post exercise balance impairments. Older adults should exercise caution immediately following exercise engaging the lower limbs to avoid fall risk.

Multivariate meta-analysis using individual participant data

When combining results across related studies, a multivariate meta-analysis allows the joint synthesis of correlated effect estimates from multiple outcomes. Joint synthesis can improve efficiency over separate univariate syntheses, may reduce selective outcome reporting biases, and enables joint inferences across the outcomes. A common issue is that within-study correlations needed to fit the multivariate model are unknown from published reports. However, provision of individual participant data (IPD) allows them to be calculated directly. Here, we illustrate how to use IPD to estimate within-study correlations, using a joint linear regression for multiple continuous outcomes and bootstrapping methods for binary, survival and mixed outcomes. In a meta-analysis of 10 hypertension trials, we then show how these methods enable multivariate meta-analysis to address novel clinical questions about continuous, survival and binary outcomes; treatment–covariate interactions; adjusted risk/prognostic factor effects; longitudinal data; prognostic and multiparameter models; and multiple treatment comparisons. Both frequentist and Bayesian approaches are applied, with example software code provided to derive within-study correlations and to fit the models.

Familiarisation to and reproducibility of cycling at 110% peak power output

AIM

This study investigated the familiarisation to and test re-test reproducibility of constant load cycling at 110% peak power output (WPEAK).

METHODS

Eleven healthy, but not cycle trained, males performed a graded incremental exercise test to ascertain WPEAK followed by three trials (T1, T2 and T3) at 110% WPEAK to exhaustion. Trials were separated by ~7 days.

RESULTS

Although there was no difference in time to exhaustion (TLIM) between T1 and T2 (P=0.100) and T2 and T3 (P=0.095) respectively, a difference was observed between T1 and T3 (P=0.046). Correlation coefficients, coefficients of determination, limits of agreement (LoA) and within-subject coefficient of variation (CV) improved across trials demonstrating T2 and T3 had the strongest relationship (T1 vs. T3: r=0.73; r2=0.53; Bias=40 s; CV=14%; T1 vs. T2: r=0.66; r2=0.43; Bias=24 s; CV=10%; T2 vs. T3: r=0.97; r2=0.95; Bias=16 s; CV=7%). There was no difference across trials for HR (P=0.12), BLa (P=0.76), RER (P=0.52), VE, (P=0.32), VO2, (P=0.33), local RPE (RPEL; P=1) and overall RPE (RPEO; P=0.91) at exhaustion or BLa (P=0.76) and pH (P=0.47) 5-minutes post-exercise.

CONCLUSION

Constant load cycling at 110% WPEAK is a reliable protocol when assessing supramaximal exercise performance after completion of two familiarisation trials.

Detecting a thienopyridine effect by platelet reactivity assessment and its implications for risk stratification

BACKGROUND

On-treatment platelet reactivity (OTR) is a predictor of clinical outcomes in patients receiving thienopyridine therapy.

OBJECTIVE

To assess whether point-of-care platelet reactivity testing can discriminate between patients who have and have not received a thienopyridine.

PATIENTS/METHODS

This was an analysis of a randomized, multicenter, pharmacodynamic trial. Subjects with coronary artery disease treated with aspirin were randomly assigned to clopidogrel 75 mg daily or prasugrel 10 mg daily for 7 days. Platelet reactivity assessment with the VerifyNow P2Y12 test was performed before study drug admistration and 24 h after the final dose. Optimal cut-offs for a detectable drug effect were identified by the use of receiver operating characteristic curve analysis.

RESULTS

A total of 54 subjects were enrolled and completed the study. The c-statistic for the identification of a thienopyridine effect was highly significant (0.93, P < 0.001), including for the clopidogrel and prasugrel groups considered separately (P < 0.001 for both). The optimal cut-off was < 213 P2Y12 reaction units (PRU), which provided a sensitivity of 80% and a specificity of 98%. This cut-off provided a sensitivity of 58% and a specificity of 100% for a clopidogrel effect, and a sensitivity of 100% and specificity of 96% for a prasugrel effect.

CONCLUSIONS

OTR of < 213 PRU is highly specific for exposure to either clopidogrel or prasugrel. This may be useful in the management of thienoypridine-treated patients who require surgery. Furthermore, this diagnostic cut-off is similar to levels of OTR that have been associated with ischemic events in thienopyridine-treated patients, supporting the contention that a lack of drug effect is the mechanistic basis for the prognostic relationship between OTR and clinical outcomes.

Evaluating the clinical usefulness of platelet function testing: considerations for the proper application and interpretation of performance measures

Various diagnostic and prognostic performance measures have been used to describe the clinical usefulness of platelet function testing in the evaluation and management of patients taking P2Y12 inhibitors, which reduce the risk for thrombosis due to their action on the platelet P2Y12 receptor. Platelet function tests are used to confirm the presence of an antiplatelet effect of a P2Y12 inhibitor, and confirmation that the pharmacodynamic effect is associated with a reduction in the rate of thrombosis. Despite this clear association, enthusiasm for the clinical usefulness of platelet function testing has been tempered based on observed sensitivity, specificity, and positive predictive value for the detection of future thrombotic events. However, evaluating the prognostic utility of a test based on diagnostic performance indicators is not appropriate because prognostic tests are not used to diagnose which patients will have events; instead, they are used to assist in risk stratification. Therefore, when evaluating the usefulness of platelet function testing, diagnostic performance measures such as sensitivity, specificity, and predictive values should focus on diagnostic performance in identifying a pharmacodynamic effect, and prognostic performance should be evaluated using prognostic performance measures such as hazard ratios and net reclassification improvement, which are comparable to other well-established risk factors for cardiovascular events.

The effects of elevated levels of sodium bicarbonate (NaHCO₃) on the acute power output and time to fatigue of maximally stimulated mouse soleus and EDL muscles

This study examined the effects of elevated buffer capacity [~32 mM HCO₃(-)] through administration of sodium bicarbonate (NaHCO₃) on maximally stimulated isolated mouse soleus (SOL) and extensor digitorum longus (EDL) muscles undergoing cyclical length changes at 37 °C. The elevated buffering capacity was of an equivalent level to that achieved in humans with acute oral supplementation. We evaluated the acute effects of elevated [HCO₃(-)] on (1) maximal acute power output (PO) and (2) time to fatigue to 60 % of maximum control PO (TLIM60), the level of decline in muscle PO observed in humans undertaking similar exercise, using the work loop technique. Acute PO was on average 7.0 ± 4.8 % greater for NaHCO₃-treated EDL muscles (P < 0.001; ES = 2.0) and 3.6 ± 1.8 % greater for NaHCO₃-treated SOL muscles (P < 0.001; ES = 2.3) compared to CON. Increases in PO were likely due to greater force production throughout shortening. The acute effects of NaHCO₃ on EDL were significantly greater (P < 0.001; ES = 0.9) than on SOL. Treatment of EDL (P = 0.22; ES = 0.6) and SOL (P = 0.19; ES = 0.9) with NaHCO₃ did not alter the pattern of fatigue. Although significant differences were not observed in whole group data, the fatigability of muscle performance was variable, suggesting that there might be inter-individual differences in response to NaHCO₃ supplementation. These results present the best indication to date that NaHCO₃ has direct peripheral effects on mammalian skeletal muscle resulting in increased acute power output.

Measurement of the ZZ production cross section and limits on anomalous neutral triple gauge couplings in proton-proton collisions at sqrt[s] = 7 TeV with the ATLAS detector

A measurement of the ZZ production cross section in proton-proton collisions at sqrt[s] = 7 TeV using data corresponding to an integrated luminosity of 1.02 fb(-1) recorded by the ATLAS experiment at the LHC is presented. Twelve events containing two Z boson candidates decaying to electrons and/or muons are observed, with an expected background of 0.3 ± 0.3(stat)(-0.3)(+0.4)(syst) events. The cross section measured in a phase-space region with good detector acceptance and for dilepton masses within the range 66 to 116 GeV is σ(ZZ → ℓ+ ℓ- ℓ+ ℓ-)(fid) = 19.4(-5.2)(+6.3)(stat)(-0.7)(+0.9)(syst) ± 0.7(lumi) fb. The resulting total cross section for on-shell ZZ production, σ(ZZ)(tot) = 8.5(-2.3)(+2.7)(stat)(-0.3)(+0.4)(syst) ± 0.3(lumi) pb, is consistent with the standard model expectation of 6.5(-0.2)(+0.3) pb calculated at the next-to-leading order in QCD. Limits on anomalous neutral triple gauge boson couplings are derived.

Single-arc volumetric-modulated arc therapy can provide dose distributions equivalent to fixed-beam intensity-modulated radiation therapy for prostatic irradiation with seminal vesicle and/or lymph node involvement

OBJECTIVES

Volumetric-modulated arc therapy (VMAT) is becoming an increasingly utilised modality for treating a variety of anatomical sites. However, the efficacy of single-arc VMAT to treat prostate cancer suspicious for extraprostatic extension was heretofore unknown. In this work, we report our institutional experience with single-arc VMAT and fixed-beam intensity-modulated radiation therapy (IMRT) for prostate cancer patients treated for seminal vesicle and/or lymph node involvement.

METHODS

Single-arc VMAT and 7- or 9-field IMRT treatment plans were compared for 10 prostate cancer patients treated for seminal vesicle involvement and/or lymph node involvement. All treatment plans were constructed using the Philips Pinnacle treatment planning system (v.9.0, Fitchburg, WI) and delivered on an Elekta Infinity radiotherapy accelerator (Crawley, UK). Resulting plans were compared using metrics that characterised dosimetry and delivery efficiency.

RESULTS

No statistically significant differences in target coverage, target homogeneity or normal tissue doses were noted between the plans (p>0.05). For prostate patients treated for seminal vesicle involvement, VMAT plans were delivered in 1.4±0.1 min (vs 9.5±2.4 min for fixed-beam IMRT) (p<0.01) and required approximately 20% fewer monitor units (p=0.01). For prostate patients treated for lymph node involvement, VMAT plans were delivered in 1.4±0.1 min (vs 11.7±1.3 min for fixed-beam IMRT) (p<0.01) and required approximately 45% fewer monitor units (p<0.01).

CONCLUSION

Single-arc VMAT plans were dosimetrically equivalent to fixed-beam IMRT plans with significantly improved delivery efficiency.

Evaluation of clopidogrel responsiveness after drug-eluting stent implantation

Clopidogrel is a cornerstone of medical therapy in patients with cardiovascular disease, reducing the rate of ischemic events in patients with acute coronary syndrome, ST elevation myocardial infarction, and those undergoing percutaneous coronary intervention (PCI). Prolonged dual antiplatelet therapy with aspirin and a thienopyridine is mandated after drug-eluting stent implantation. However, there is substantial variability in the pharmacokinetics and pharmacodynamics of clopidogrel among individuals, and a lack of effect has been associated with adverse outcome after PCI, including drug-eluting stent thrombosis. The development of platelet function assays that can be performed in the clinical laboratory or at the point-of-care has made it possible to integrate the evaluation of clopidogrel response into clinical practice. Clinical utilization of platelet function testing requires an understanding of the types of methodologies that are available, the interpretation of the results that are provided, and the different potential treatment options in patients who are identified to be at risk. Several ongoing randomized clinical trials are testing the safety and efficacy of individualized antiplatelet therapy based on platelet function testing to reduce ischemic events after PCI with drug-eluting stents.

Cooling strategies improve intermittent sprint performance in the heat of athletes with tetraplegia

BACKGROUND

Precooling has been shown to enhance performance in repeated sprint exercise in able-bodied subjects in a hot environment. Spinal cord injury causes thermoregulatory impairment with a detrimental effect on performance. This study assessed whether cooling strategies before and during exercise in the heat enhances sprint performance in athletes with tetraplegia.

METHODS

Eight male athletes with tetraplegia performed intermittent arm crank exercise in the heat (32.0 degrees C (0.1 degrees C); humidity, 50% (0.1%)) for a maximum of 60 min or until exhaustion. Trials involved a no-cooling control (CON), precooling (PRE) or cooling during exercise (DUR). Each intermittent sprint protocol consisted of varied periods of passive rest, maximal sprinting and active recovery.

RESULTS

Both PRE and DUR cooling strategies improved the ability of the athletes to repeatedly perform high-intensity sprints, with times to exhaustion (TTE), whereas during the CON trial, athletes demonstrated a reduction in the total number of sprints and TTE (47.2 (10.8), 52.8 (5.8) and 36.2 (9.6) min for CON, PRE and DUR, respectively). Core temperature was significantly higher for CON (37.3 degrees C (0.3 degrees C)) when compared with both PRE and DUR (36.5 degrees C (0.6 degrees C) and 37.0 degrees C (0.5 degrees C), respectively, p<0.01). Ratings of perceived exertion and thermal sensation upon exhaustion or completion were not different.

CONCLUSIONS

Athletes with tetraplegia should use a precooling or during-exercise cooling strategy specific to the characteristics of their sport when exercising in hot conditions.

The influence of ramp rate on VO2peak and "excess" VO2 during arm crank ergometry

The principal aim of this study was to examine how different ramp rates influenced the attainment of peak physiological responses during incremental arm crank ergometry (ACE). Additionally, the study examined whether there was any evidence for the development of an "excess" VO (2) during ACE due to upward curvi-linearity in the VO (2)-work rate relationship, and whether this was influenced by the ramp rate. Sixteen physically active, though non-specifically trained, men (mean +/- S age 30 +/- 8 years; height 1.79 +/- 0.07 m; body mass 84.7 +/- 13.2 kg) volunteered to participate. Having completed a familiarisation test, all subjects returned to the laboratory to complete two ramp tests on an electrically-braked ergometer in a counter-balanced order. Both ramp tests started at 60 W with work rate subsequently incremented by either 6 or 12 W . min (-1). Pulmonary gas exchange was measured breath-by-breath throughout the tests. Subjects achieved a greater final work rate during the 12 W . min (-1) test compared to the 6 W . min (-1) test (168 +/- 28 vs. 149 +/- 26 W; p < 0.001). The VO (2peak) (3.06 +/- 0.65 vs. 2.96 +/- 0.48 L . min (-1); p = 0.27), HR (peak) (179 +/- 15 vs. 177 +/- 16 b . min (-1); p = 0.17) and V.E (peak) (112 +/- 22 vs. 105 +/- 16 L . min (-1); p = 0.09) were not different between the tests, but VCO (2peak) (3.54 +/- 0.64 vs. 3.27 +/- 0.46 L . min (-1); p = 0.01) RER (peak) (1.17 +/- 0.07 vs. 1.11 +/- 0.06; p < 0.001), and end-exercise blood (lactate) (11.9 +/- 2.1 vs. 10.8 +/- 2.6 mmol . L (-1); p = 0.005) were all higher in the 12 W . min (-1) test. An "excess" VO (2) was observed in 13 out of 16 tests at 12 W . min (-1) and in 15 out of 16 tests at 6 W . min (-1). Neither the magnitude of the "excess" VO (2) (0.42 +/- 0.41 vs. 0.37 +/- 0.18 L . min (-1); p = 0.66) nor the VO (2) at which the V.O (2)-work rate relationship departed from linearity (2.17 +/- 0.34 vs. 2.18 +/- 0.32 L . min (-1); p = 0.94) were significantly different between the two ramp tests. These data indicate that differences in ramp rate within the range of 6 - 12 W . min (-1) influence the peak values of work rate, VCO (2) and RER, but do not influence peak values of VO (2) or HR during ACE. The development of an "excess" VO (2) appears to be a common feature of ramp exercise in ACE, although the mechanistic basis for this effect is presently unclear.

The effect of crank rate on physiological responses and exercise efficiency using a range of submaximal workloads during arm crank ergometry

This study examined the effects of variations in crank rate on physiological responses during submaximal arm ergometry. Fifteen non-specifically trained male subjects volunteered to participate in this study. Each subject undertook a discontinuous arm crank ergometry test (30, 50, 70, 90 W) on three separate occasions using crank rates of 50, 70, and 90 rev.min(-1). Respiratory parameters and heart rate were continuously monitored. An 80-microL capillary blood sample was obtained immediately following each exercise bout for the determination of whole blood lactate. Measures of efficiency were calculated using specific caloric equivalents of oxygen consumption (V(O2)). Heart rate was lowest (p < 0.05) at 30, 50, and 70 W using 50 rev.min(-1). Values of gross and net efficiency tended to be higher (p < 0.05) using 50 rev.min (-1) at the lower absolute workloads, but no differences (p > 0.05) were observed between the three crank rates at 90 W. No differences (p > 0.05) were observed between crank rates for delta efficiency. This study confirms that variations in crank rate can influence gross and net values of V(O2) and exercise efficiency at low absolute workloads, but crank rate ceases to be an influential factor at moderate workloads. Further research is required to identify the specific mechanisms underpinning the observations reported in the present study relating to the interaction between crank rate, workload, and exercise efficiency during arm crank ergometry.

The expected burden of mesothelioma mortality in Great Britain from 2002 to 2050

The British mesothelioma register contains all deaths from 1968 to 2001 where mesothelioma was mentioned on the death certificate. These data were used to predict the future burden of mesothelioma mortality in Great Britain. Poisson regression analysis was used to model male mesothelioma deaths from 1968 to 2001 as a function of the rise and fall of asbestos exposure during the 20th century, and hence to predict numbers of male deaths in the years 2002–2050. The annual number of mesothelioma deaths in Great Britain has risen increasingly rapidly from 153 deaths in 1968 to 1848 in 2001 and, using our preferred model, is predicted to peak at around 1950 to 2450 deaths per year between 2011 and 2015. Following this peak, the number of deaths is expected to decline rapidly. The eventual death rate will depend on the background level and any residual asbestos exposure. Between 1968 and 2050, there will have been approximately 90 000 deaths from mesothelioma in Great Britain, 65 000 of which will occur after 2001.

The influence of step and ramp type protocols on the attainment of peak physiological responses during arm crank ergometry

The present study examined the impact of two exercise protocols on the attainment of peak physiological responses during arm crank ergometry (ACE). Fourteen physically active, although non-specifically trained male subjects completed two V.O (2) peak tests using an electrically braked arm ergometer (Lode Angio, Groningen, Netherlands). The tests consisted of a stepwise or rampwise increase in external workload. The order of tests was randomised and each test was separated by at least two days. Respiratory data were collected continuously using an on-line gas analysis system with sample time set at 30 s. Fingertip capillary blood samples ( approximately 20 microL) were collected at volitional exhaustion and at minute intervals for 7 min of passive recovery for the determination of peak whole blood lactate concentration. Time on the test (T (lim); s), peak minute power (PMP; W), and total work done (TWD; kJ) were also recorded. In addition to determining systematic bias using separate independent t-tests, the level of agreement was also examined by way of calculating the 95 % limits of agreement. Sub-maximal values of V.O (2), V.E, and HR were similar (p > 0.05) between test when the amount of external work completed was taken into consideration. There was no systematic bias (p > 0.05) for mean (+/- s) peak values of V.O (2) (3.12 [0.37] vs. 3.04 [0.38] L . min (-1)) or any other parameter between the step and ramp tests, respectively. Mean values of T (lim), PMP, and TWD were also similar (p > 0.05) between tests. However, the level of agreement for peak values of all test parameters was low. It is therefore concluded that while either test can be considered as being suitable for the purpose of eliciting V.O (2) peak and other physiological responses using ACE, they should not be used interchangeably for the purpose of assessing parameters linked to the aerobic capacity of the upper-body.

Effects of two cooling strategies on thermoregulatory responses of tetraplegic athletes during repeated intermittent exercise in the heat

Athletes with spinal cord injury (SCI), and in particular tetraplegia, have an increased risk of heat strain and consequently heat illness relative to able-bodied individuals. Strategies that reduce the heat strain during exercise in a hot environment may reduce the risk of heat illness. To test the hypotheses that precooling or cooling during intermittent sprint exercise in a heated environment would attenuate the rise in core temperature in tetraplegic athletes, eight male subjects with SCI (lesions C(5)-C(7); 2 incomplete lesions) undertook four heat stress trials (32.0 +/- 0.1 degrees C, 50 +/- 0.1% relative humidity). After assessment of baseline thermoregulatory responses at rest for 80 min, subjects performed three intermittent sprint protocols for 28 min. All trials were undertaken on an arm crank ergometer and involved a no-cooling control (Con), 20 min of precooling (Pre), or cooling during exercise (Dur). Trials were administered in a randomized order. After the intermittent sprint protocols, mean core temperature was higher during Con (37.3 +/- 0.3 degrees C) compared with Pre and Dur (36.5 +/- 0.6 degrees C and 37.0 +/- 0.5 degrees C, respectively; P < 0.01). Moreover, perceived exertion was lower during Pre (13 +/- 2; P < 0.01) and Dur (12 +/- 1; P < 0.01) compared with Con (14 +/- 2). These results suggest that both precooling and cooling during intermittent sprint exercise in the heat reduces thermal strain in tetraplegic athletes. The cooling strategies also appear to show reduced perceived exertion at equivalent time points, which may translate into improved functional capacity.

Cost-effectiveness of fluticasone propionate in the treatment of chronic obstructive pulmonary disease: a double-blind randomized, placebo-controlled trial

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a debilitating disease and places a large financial burden on health-care systems and society. We prospectively evaluated the cost-effectiveness offluticasone propionate (FP) treatment in patients with moderate-to-severe COPD, who were symptomatic on regular bronchodilator therapy.

METHODS

An economic analysis was performed in a 6-month, randomized, double-blind clinical trial comparing FP 1,000 microg/day with placebo in 281 patients aged 45-79 years with symptomatic moderate-to-severe COPD. Data on clinical efficacy, health-care resource use and productivity loss associated with the management of COPD were prospectively collected. The main outcome measures were the incremental cost-effectiveness of achieving a > or = 10% improvement in FEV1 and of remaining exacerbation-free throughout the study. The economic evaluation was costed from the perspective of the NHS (direct costs) and of society (direct and indirect costs).

RESULTS

FP was significantly more effective than placebo in terms of the proportions of patients demonstrating a > or = 10% improvement in FEV1 (32 vs. 19%; P = 0.02) and remaining free of moderate/severe exacerbations (75 vs. 63%; P = 0.02). The difference between the groups in total costs was not significantly different. Incremental cost-effectiveness analyses showed that the additional clinical benefits of FP relativeto placebo, in terms of a > or = 10% improvement in FEV1 or an increased number of patients free of moderate/severe exacerbations, were achieved at minimal additional costs from an NHS perspective (additional 0.25 pounds per day for bath) or at a net saving from a societal perspective. Sensitivity analysis showed that these results were robust to changes in the underlying assumptions.

CONCLUSIONS

Treatment with FP was associated with statistically significant clinical benefits in patients with moderate-to-severe COPD currently symptomatic on regular bronchodilator therapy. As the differences in direct and total costs compared with placebo were small and non-significant, this treatment can be considered cost-effective in this patient population.

Thermoregulatory responses during prolonged upper-body exercise in cool and warm conditions

The thermoregulatory responses of upper-body trained athletes were examined at rest, during prolonged arm crank exercise and recovery in cool (21.5 +/- 0.9 degrees C, 43.9 +/- 10.1% relative humidity; mean +/- s) and warm (31.5 +/- 0.6 degrees C, 48.9 +/- 8.4% relative humidity) conditions. Aural temperature increased from rest by 0.7 +/- 0.7 degrees C (P< 0.05) during exercise in cool conditions and by 1.6 +/- 0.7 degrees C during exercise in warm conditions (P< 0.05). During exercise in cool conditions, calf skin temperature decreased (1.5 +/- 1.3 degrees C), whereas an increase was observed during exercise in warm conditions (3.0 +/- 1.7 degrees C). Lower-body skin temperatures tended to increase by greater amounts than upper-body skin temperatures during exercise in warm conditions. No differences were observed in blood lactate, heart rate or respiratory exchange ratio responses between conditions. Perceived exertion at 45 min of exercise was greater than that reported at 5 min of exercise during the cool trial (P< 0.05), whereas during exercise in the warm trial the rating of perceived exertion increased from initial values by 30 min (P < 0.05). Heat storage, body mass losses and fluid consumption were greater during exercise in warm conditions (7.06 +/- 2.25 J x g(-1) x degrees C(-1), 1.3 +/- 0.5 kg and 1,038 +/- 356 ml, respectively) than in cool conditions (1.35 +/- 0.23 J x g(-1) x degrees C(-1), 0.8 +/- 0.2 kg and 530 +/- 284 ml, respectively; P < 0.05). The results of this study indicate that the increasing thermal strain with constant thermal stress in warm conditions is due to heat storage within the lower body. These results may aid in understanding thermoregulatory control mechanisms of populations with a thermoregulatory dysfunction, such as those with spinal cord injuries.

Cost-effectiveness of fluticasone propionate administered via metered-dose inhaler plus babyhaler spacer in the treatment of asthma in preschool-aged children

STUDY OBJECTIVES

To evaluate the cost-effectiveness of inhaled fluticasone propionate (FP) in children aged 12 to 47 months with asthma symptoms.

DESIGN

A retrospective economic analysis conducted from the perspective of the Danish health-care system, based on clinical data from a 12-week study.

SETTING

Thirty-three outpatient centers in nine countries.

PATIENTS

Two hundred thirty-seven children aged 12 to 47 months with documented history of recurrent wheeze or asthma symptoms.

INTERVENTIONS

Two dosages of FP, 100 microg/d and 200 microg/d, and placebo administered in two divided doses via a metered-dose inhaler and a Babyhaler (Glaxo Wellcome; Middlesex, UK) spacer device.

MEASUREMENTS

Effectiveness in terms of asthma exacerbations, control of cough and wheeze symptoms, symptom-free days, overall direct costs of asthma management in Danish kroner at 1999 prices, and mean and incremental cost-effectiveness ratios.

RESULTS

FP, 200 microg/d, was significantly more effective than placebo treatment in terms of the proportion of exacerbation-free patients (73.7% vs 59.8%; p = 0.025) and patients experiencing a > or = 25% improvement in cough symptoms (57.9% vs 39.0%; p = 0.018). The costs per exacerbation-free patient, per patient with a > or = 25% improvement in cough and wheeze symptoms from baseline, and per symptom-free day were lower in the FP groups than in the placebo group. The incremental cost-effectiveness ratios for these end points indicated that the additional benefits of FP, 200 microg/d, were achieved at a lower overall cost compared with placebo treatment.

CONCLUSIONS

From the perspective of the Danish health-care system, FP, 100 microg bid, administered via the Babyhaler inhalation device was cost-effective relative to standard therapy with bronchodilators alone.

The influence of crank rate on peak oxygen consumption during arm crank ergometry

The aim of this study was to assess the influence of three imposed crank rates on the attainment of peak oxygen consumption (VO2peak) and other physiological responses during incremental arm crank ergometry. Twenty physically active, although non-specifically trained, males volunteered for the study. They completed an exercise protocol using an electrically braked arm ergometer (Lode Angio, Groningen, Netherlands) at crank rates of 60, 70 and 80 rev x min(-1). The order of tests was randomized and they were separated by at least 2 days. Peak VO2 was significantly higher (P < 0.05) at 70 and 80 rev x min(-1) than at 60 rev x min(-1). Peak ventilation volume increased as a function of crank rate and was higher (P < 0.05) at 80 than at 60 rev x min(-1). Peak heart rate was higher (P < 0.05) at 70 and 80 rev x min(-1) than at 60 rev x min(-1). Furthermore, 70 and 80 rev x min(-1) resulted in an extended test time compared with 60 rev x min(-1). The greater physiological responses observed during the tests at the two faster crank rates might have been the result of a postponement of acute localized neuromuscular fatigue, allowing for more work to be completed. We recommend, therefore, that an imposed crank rate between 70 and 80 rev x min(-1) should be used to elicit VO2peak and other physiological responses in arm crank ergometry.

Comparison of once daily fluticasone propionate aqueous nasal spray with once daily budesonide reservoir powder device in patients with perennial rhinitis

BACKGROUND

Previous studies comparing the corticosteroids fluticasone propionate (FP) and budesonide (BUD) in both perennial and seasonal rhinitis have shown no consistent difference between treatments. However, the therapeutic outcomes may have been influenced by study design.

OBJECTIVE

To compare the effect of FP aqueous nasal spray (ANS; 200 microg/day) with BUD reservoir powder device (RPD; 200 microg/day) on rhinitis symptoms, productivity loss and device preference in patients with perennial rhinitis.

METHODS

After a 2-week run-in period, 440 patients were randomized to receive either FPANS, BUD RPD or matched placebo (ANS or RPD) for 8 weeks, followed by an open-label 4-week follow-up treatment with FPANS. Patients completed diary card visual analogue scores for nasal symptoms, and questionnaires on satisfaction with the treatment and preferred choice of device.

RESULTS

During weeks 1-4, the visual analogue total nasal symptom scores (VATNS) in the FPANS group were significantly lower than scores in the BUD RPD group (mean difference = -17.8; 95% CI = -34.4, -1.3; P = 0.036). FPANS also significantly reduced the VATNS compared with the ANS placebo at all time-points assessed (P < or = 0.005). BUD RPD did not significantly differ from the RPD placebo at weeks 5-8 (P = 0.167), or the ANS placebo at any time-point (P < or = 0.151). Over the 8-week treatment period FPANS was significantly more effective than BUD RPD at reducing sneezing (mean difference = -4.4; 95% CI = -8.6, -0.3; P = 0.036) and nasal itching (mean difference = -5.3; 95% CI = -9.9, -0.8; P = 0.022), and was significantly superior to the ANS placebo for all symptoms assessed at weeks 1-4 and 1-8 (P < 0.016). At the same time-points BUD RPD was no better at alleviating nasal itching than the RPD placebo (P < or = 0.306), and compared with the ANS placebo, significantly reduced only one symptom; nasal blockage (P < or = 0.016). After 8 weeks of treatment, patients preferred the ANS device to the RPD (P < 0.001), and at 12 weeks a significantly greater number of patients were satisfied with FPANS treatment compared with BUD RPD (P = 0.0019) or the respective placebos (P = 0.0001).

CONCLUSION

FPANS and BUD RPD are effective therapies with a good safety profile for the treatment of perennial rhinitis but, in this direct placebo-controlled comparison, FPANS was more efficacious than BUD RPD, and the patients preferred the ANS device to the RPD.

Cost-efficacy comparison of inhaled fluticasone propionate and budesonide in the treatment of asthma

BACKGROUND

The results of a recent meta-analysis comparing 2 inhaled corticosteroids, fluticasone propionate (FP) and budesonide, demonstrated that FP had an improved efficacy-to-safety ratio compared with budesonide. However, limited data are available on the relative economic benefits of these 2 regimens.

OBJECTIVE

This pharmacoeconomic analysis used individual patient data from studies in the meta-analysis to compare the relative cost-efficacy of 2 asthma regimens from the perspective of a US third-party payer.

METHODS

This analysis included all 7 studies in the meta-analysis that compared budesonide with FP dosed at approximately half the dose of budesonide and that included measurement of daily morning peak expiratory flow (PEF).

RESULTS

The total daily per-person cost of asthma management was higher for patients treated with budesonide than with FP ($3.00 vs $2.25, respectively). Treatment with FP had greater cost-efficacy than treatment with budesonide, based on a range of outcome measures that included improvement in morning PEF, symptom-free days, and episode-free days. The daily cost per effectively treated patient (an increase in PEF of > or = 10%) was $5.62 with FP and $10.05 with budesonide. The cost per symptom-free day was $4.36 with FP, compared with $6.67 with budesonide. The cost per episode-free day was $5.60 with FP and $9.42 with budesonide. The pharmacoeconomic difference continued to favor FP as the criteria for success were made more stringent and the cost of budesonide was lowered.

CONCLUSION

Based on data from the 7 randomized, controlled trials, treatment of asthma with FP was more effective and less expensive, using US health care assumptions and costs, than treatment with budesonide.

Patient and physician perspectives on the impact and management of perennial and seasonal allergic rhinitis

Patient and physician perspectives on the impact and management of perennial (PAR) and seasonal allergic rhinitis (SAR) were studied. In all, 2139 subjects were questioned about their medical conditions, severity and frequency of symptoms and satisfaction with treatment. A group of general practitioners (GPs) were also invited to discuss their experiences in the management of rhinitis. In this UK survey, allergic rhinitis was more common than asthma, hypertension, skin rashes, eczema and diabetes. The prevalence of SAR and PAR was 15% and 2%, respectively. Sneezing and runny nose were the most common symptoms and GPs were the main contact for advice and treatment (54% of patients). Symptoms were well-controlled in 32% of patients. Allergic rhinitis affected work, home and social life in 29%, 34% and 30% of patients, respectively. The GPs considered PAR to be more difficult to treat than SAR, and GP and patient level of satisfaction in the treatment of PAR was low. This suggests that education of patients and physicians on the benefits of allergen avoidance, and the selective use of the highly effective therapies available on prescription could improve the level of satisfaction with therapy. Adherence to current guidelines on the management of rhinitis could lead to an effective, structured treatment plan for patients.

Cost-effectiveness of salmeterol/fluticasone propionate combination product 50/250 microg twice daily and budesonide 800 microg twice daily in the treatment of adults and adolescents with asthma. International Study Group

Despite a good understanding of the disease and its treatments, asthma continues to place a large economic burden on healthcare systems. As such, it is important to consider the economic impact of alternative therapeutic options for the treatment of this condition to ensure that scarce resources are used in the most efficient manner possible. Thus, the aim of asthma management from an economic perspective is to reduce the burden of this disease through maximizing health gain with available resources. A prospective economic analysis was conducted as part of a multicentre, randomized, double-blind, comparative trial of salmeterol/fluticasone propionate combination product (SFC) 50/250 microg twice daily vs. budesonide (800 microg twice daily) in adults and adolescents with asthma who were symptomatic despite treatment with inhaled corticosteroids at doses of 800-1200 microg day(-1). Treatment effectiveness was measured in terms of successfully-treated weeks, defined as a > or =5% improvement in morning peak expiratory flow, episode-free days (a day without the need for rescue medication, no nocturnal awakening or adverse events) and symptom-free days. Cost-effectiveness analyses were performed using direct healthcare and drug costs, from the perspective of the Swedish healthcare system (1998 prices), with appropriate sensitivity analyses to test the robustness of the findings. Overall, SFC produced significantly higher (P<0.001) proportions of successfully-treated weeks, episode-free days and symptom-free days. Direct asthma management costs were similar between the two groups [SEK19.6 ($US2.4) for SFC vs. SEK18.5 (SUS2.2) for budesonide]. The cost per successfully-treated week was lower for SFC than for budesonide [SEK204 ($US24.8) vs. SEK300 ($US36.4) per week], as were the costs per episode-free day [SEK51.1 ($US6.2) vs. SEK75.1 ($US9.1) per day] and symptom-free day [SEK42.2 ($US5.1) vs. SEK53.0 ($US6.4) per day]. Incremental cost-effectiveness ratios showed that the additional costs to achieve additional benefits with SFC were minimal. Costs per additional successfully-treated week, symptom-free day and episode-free day with SFC were SEK31.6 ($US3.9), SEK9.2 ($US1.1) and SEK7.7 ($US0.9), respectively, relative to budesonide. Sensitivity analysis showed that the results were stable over a wide range of assumptions. The results suggest that SFC is a more cost-effective treatment than budesonide in the management of moderate to severe asthma.

Impact of suppressive antiviral therapy on the health related quality of life of patients with recurrent genital herpes infection

OBJECTIVE

To investigate whether suppressive antiviral therapy improves health related quality of life in patients with recurrent genital herpes.

METHODS

Health related quality of life was measured using the disease specific recurrent genital herpes quality of life questionnaire (RGHQoL) as part of a randomized, double blind, 52 week, placebo controlled, dose ranging study of once and twice daily valaciclovir or aciclovir for the suppression of recurrent genital herpes in patients with six or more recurrences per year.

RESULTS

Of 1479 participants, 1349 patients completed the baseline questionnaire. There were no significant baseline differences in RGHQoL score between any of the treatment groups. After 3 months there were significantly greater improvements in mean RGHQoL scores for all active treatment groups compared with placebo (p < 0.05). Mean RGHQoL score improvements from baseline remained significantly higher in the active treatment groups than in the placebo group after 6 and 12 months, indicating that the improved health related quality of life in patients receiving suppressive antiviral therapy was sustained over a prolonged period of time.

CONCLUSION

Suppressive antiviral therapy is an effective strategy for improving the quality of life of patients with recurrent genital herpes. These improvements in quality of life are sustained over time, thus enhancing the clinical benefit in the long term management of this condition.

Thermoregulatory responses of spinal cord injured and able-bodied athletes to prolonged upper body exercise and recovery

STUDY DESIGN

Single trial, two factor repeated measures design.

SETTING

England, Cheshire.

OBJECTIVES

To examine the thermoregulatory responses of able-bodied (AB) athletes, paraplegic (PA) athletes and a tetraplegic (TP) athlete at rest, during prolonged upper body exercise and recovery.

METHODS

Exercise was performed on a Monark cycle ergometer (Ergomedic 814E) adapted for arm exercise at 60% VO2 peak for 60 min in cool conditions ('normal' laboratory temperature; 21.5+/-1.7 degrees C and 47+/-7.8% relative humidity). Aural and skin temperatures were continually monitored.

RESULTS

Mean (+/-S.D.) peak oxygen uptake values were greater (P<0. 05) for the AB when compared to the PA (3.45+/-0.45 l min-1 and 2. 00+/-0.46 l min-1, respectively). Peak oxygen uptake for the TP was 0.91 l min-1. At rest, aural temperature was similar between groups (36.2+/-0.3 degrees C, 36.3+/-0.3 degrees C and 36.3 degrees C for AB, PA and TP athletes, respectively). During exercise, aural temperature demonstrated relatively steady state values increasing by 0.6+/-0.4 degrees C and 0.6+/-0.3 degrees C for the AB and PA athletes, respectively. The TP athlete demonstrated a gradual rise in aural temperature throughout the exercise period of 0.9 degrees C. Thigh skin temperature increased by 1.3+/-2.5 degrees C for the AB athletes (P<0.05) whereas the PA athletes demonstrated little change in temperature (0.1+/-3.4 degrees C and -0.7 degrees C respectively). Calf temperature increased for the PA athletes by 1.0+/-3.6 degrees C (P<0.05), whereas a decrease was observed for the AB athletes of -1.0+/-2.0 degrees C (P<0.05) during the exercise period. During 30 min of passive recovery, the AB athletes demonstrated greater decreases in aural temperatures than those for the PA athletes (P<0. 05). Aural temperature for the TP increased peaking at 5 min of recovery remaining elevated until the end of the recovery period. Fluid consumption and weight losses were similar for the AB and PA athletes (598+/-433 ml and 403+/-368 ml; 0.38+/-0.39 kg and 0.38+/-0. 31 kg, respectively), whereas changes in plasma volume were greater for the AB athletes (-9.8+/-5.8% and 4.36+/-4.9%, respectively; P<0. 05).

CONCLUSION

The results of this study suggest that under the experimental conditions PA athletes are at no greater thermal risk than AB athletes. A relationship between the available muscle mass for heat production and sweating capacity appears evident for the maintenance of thermal balance. During recovery from exercise, decreases in aural temperature, skin temperature and heat storage were greatest for the AB athletes with the greatest capacity for heat loss and lowest for the TP athlete with the smallest capacity for heat loss. Initial observations on one TP athlete suggest substantial thermoregulatory differences when compared to AB and PA athletes.