Multisite reliability of cognitive BOLD data

Investigators perform multi-site functional magnetic resonance imaging studies to increase statistical power, to enhance generalizability, and to improve the likelihood of sampling relevant subgroups. Yet undesired site variation in imaging methods could off-set these potential advantages. We used variance components analysis to investigate sources of variation in the blood oxygen level-dependent (BOLD) signal across four 3-T magnets in voxelwise and region-of-interest (ROI) analyses. Eighteen participants traveled to four magnet sites to complete eight runs of a working memory task involving emotional or neutral distraction. Person variance was more than 10 times larger than site variance for five of six ROIs studied. Person-by-site interactions, however, contributed sizable unwanted variance to the total. Averaging over runs increased between-site reliability, with many voxels showing good to excellent between-site reliability when eight runs were averaged and regions of interest showing fair to good reliability. Between-site reliability depended on the specific functional contrast analyzed in addition to the number of runs averaged. Although median effect size was correlated with between-site reliability, dissociations were observed for many voxels. Brain regions where the pooled effect size was large but between-site reliability was poor were associated with reduced individual differences. Brain regions where the pooled effect size was small but between-site reliability was excellent were associated with a balance of participants who displayed consistently positive or consistently negative BOLD responses. Although between-site reliability of BOLD data can be good to excellent, acquiring highly reliable data requires robust activation paradigms, ongoing quality assurance, and careful experimental control.     

Women's perceptions of caesarean birth: a Roy international study

The purpose of this Roy adaptation model-based multi-site international mixed method study was to examine the relations of type of caesarean birth (unplanned/planned), number of caesarean births (primary/repeat), and preparation for caesarean birth to women's perceptions of and responses to caesarean birth. The sample included 488 women from the United States (n = 253), Finland (n = 213), and Australia (n = 22). Path analysis revealed direct effects for type of and preparation for caesarean birth on responses to caesarean birth, and an indirect effect for preparation on responses to caesarean birth through perception of birth the experience.     

Blockade of CTLA-4 on both effector and regulatory T cell compartments contributes to the antitumor activity of anti–CTLA-4 antibodies

Cytotoxic T lymphocyte–associated antigen 4 (CTLA-4) is a critical negative regulator of immune responses. Uniquely among known inhibitory receptors, its genetic ablation results in a fulminating and fatal lymphoproliferative disorder. This central regulatory role led to the development of antibodies designed to block CTLA-4 activity in vivo, aiming to enhance immune responses against cancer. Despite their preclinical efficacy and promising clinical activity against late stage metastatic melanoma, the critical cellular targets for their activity remains unclear. In particular, debate has focused on whether the effector T cell (T_eff) or regulatory T cell (T reg cell) compartment is the primary target of antibody-mediated blockade. We developed a mouse expressing human instead of mouse CTLA-4, allowing us to evaluate the independent contributions of CTLA-4 blockade of each T cell compartment during cancer immunotherapy in an in vivo model of mouse melanoma. The data show that although blockade on effector cells significantly improves tumor protection, unicompartmental blockade on regulatory cells completely fails to enhance antitumor responses. However, concomitant blockade of both compartments leads to a synergistic effect and maximal antitumor activity. We conclude that the combination of direct enhancement of T_eff cell function and concomitant inhibition of T reg cell activity through blockade of CTLA-4 on both cell types is essential for mediating the full therapeutic effects of anti–CTLA-4 antibodies during cancer immunotherapy.The T cell receptor CTL-associated antigen 4 (CTLA-4) is recognized as a critical inhibitory regulator of the early stages of T cell expansion, opposing the actions of CD28-mediated costimulation. Genetic disruption of CTLA-4 expression results in a polyclonal CD4-dominated lymphoproliferative syndrome, which is characterized by T cell infiltration of multiple organs and early lethality within 3–4 wk after birth (Waterhouse et al., 1995). This pathology is dependent on interactions of CD28 with its ligands B7-1 and B7-2, as indicated by the lack of disease in CTLA-4/B7-1/B7-2 triple KO (TKO) mice and the protection afforded by repeated administration of CTLA-4 Ig in CTLA-4 KO mice (Mandelbrot et al., 1999).Based on the recognition of the importance of CTLA-4 in the regulation of immune responses, blocking antibodies against both mouse and human forms have been investigated for their potential to boost immunological responses against cancer. Data from preclinical models support a significant role for CTLA-4 blockade in the induction of durable antitumor immunity (Leach et al., 1996; Shrikant et al., 1999; van Elsas et al., 1999; Quezada et al., 2006). Furthermore, clinical trials with human anti–human CTLA-4 (aHuCTLA-4) mAbs show promising early results in the treatment of late-stage metastatic melanoma (Hodi et al., 2003; Phan et al., 2003; Ribas et al., 2005; Peggs et al., 2008). Despite growing experience of their use in the treatment of human cancers, the precise mechanisms underpinning CTLA-4–mediated control of the immune response and, more specifically, the antitumor activity of anti–CTLA-4 antibodies, remain elusive. Two independent, but not mutually exclusive, hypotheses invoke cell autonomous and non–cell autonomous mechanisms.A cell autonomous mechanism of action for CTLA-4, with CTLA-4 acting when expressed in cis of CD28, is supported by several lines of data. Studies of both in vitro and in vivo systems show higher proliferative capacity of CTLA-4–deficient CD4⁺ and CD8⁺ T cells when compared with their WT counterparts (Chambers et al., 1998, 1999; Greenwald et al., 2001, 2002). Several mechanisms have been proposed to explain such cell autonomous inhibition, including CTLA-4 outcompeting CD28 for binding to its ligands B7-1 and B7-2 (for review see van der Merwe and Davis, 2003), as well as direct inhibitory signaling through the CTLA-4 cytoplasmic tail (Carreno et al., 2000). In contrast, it has remained more contentious whether CTLA-4 expressed in trans by CD4⁺CD25⁺Foxp3⁺ regulatory T cells (T reg cells) has a direct role in their suppressive function. Constitutive expression of CTLA-4 is a cardinal feature of T reg cells, although the majority of CTLA-4 is found intracellularly in both T reg and conventional T cells, even after activation. Two major findings have supported a non–cell autonomous inhibitory function of CTLA-4. The first is the dominant protection against lethal lymphoproliferation afforded by WT mixed chimerism in the bone marrow transplant model using CTLA-4^−/− and WT donors (Bachmann et al., 1999). The second is the ability of CTLA-4 blockade to abrogate the protective effect mediated by CD4⁺CD25⁺ T cells in an adoptive transfer model of colitis (where CD4⁺CD45RB^high T cell transfer into immunodeficient mice normally results in severe colitis; Read et al., 2000, 2006). However, interpretation of the impact of anti–CTLA-4 on T reg cells is confounded by the direct effects that CTLA-4 blockade has on non–T reg cells within the same systems, whereas isolation of Foxp3-expressing CD4⁺ T cells from CTLA-4^−/− animals requires immunological manipulations that may have influenced T reg cell development (e.g., the use of TKO mice; Read et al., 2006). Nonetheless, the recent demonstration that T reg cell–specific CTLA-4 deficiency in conditional KO (CKO) mice is associated with a profound reduction in their suppressive capacity has definitively proven a role for CTLA-4 in T reg cell–mediated suppression (Wing et al., 2008). CKO mice developed a lethal autoimmune lymphoproliferative syndrome with a slightly slower tempo than CTLA-4^−/− mice, illustrating the essential role that CTLA-4 plays in T reg cell function.These recent findings have direct relevance for the clinical development of anti–CTLA-4 antibodies. They highlight the question of which are the relevant cellular targets for their antitumor activity. To date, effector T cells (T_eff) have been thought to be the most relevant target for therapeutic activity, but the data from the CKO experiments suggest otherwise by highlighting the critical role that CTLA-4 plays in T reg cell function. The answer is important for the rational development of combinatorial immunotherapeutic strategies. The lack of functional CTLA-4–expressing T reg cell at tumor engraftment in the CKO studies proved sufficient to prevent sustained tumor growth in 60% of mice (Wing et al., 2008). Both we and others, however, have demonstrated that targeted depletion of T reg cells (either with anti-CD25 mAbs or in Foxp3-DTR transgenic mice) can be effective as a prophylaxis but not as a treatment once tumor engraftment is established, a setting which better reflects their clinical usage (Onizuka et al., 1999; Quezada et al., 2008). In addition, it is possible that quantitative or qualitative differences may exist between CTLA-4 ablation and antibody blockade. Thus, the relative importance of antibody-mediated blockade of CTLA-4 in trans on the regulatory compartment as compared with blockade in cis on the nonregulatory compartment in tumor models and clinical applications remains unclear.In this study, we used mice expressing human instead of mouse CTLA-4 to allow assessment of the influence of uni- and bicompartmental blockade on T reg and non–T reg cell compartments during in vitro assays and in an in vivo tumor model of B16/BL6 melanoma. We show that unicompartmental antibody-mediated blockade of CTLA-4 on T reg cells modestly reduced suppressive capacity during in vitro suppressor assays. This effect was exaggerated by use of CTLA4^−/− T reg cells derived from stable bone marrow chimeras, from which T reg cells could be isolated without significant contamination by activated effectors. Intriguingly, unicompartmental antibody-mediated blockade of CTLA-4 on T reg cells combined with a GM-CSF–secreting cellular vaccine (Gvax) had no impact on tumor growth kinetics when given after engraftment. Blockade of the non–T reg cell compartment in combination with Gvax resulted in delayed tumor growth and rejection in 12/30 (40%) mice, whereas blockade of both T reg and non–T reg cell populations resulted in rejection in 22/30 (73%; P = 0.0017). Our data are the first to demonstrate the critical importance of synergy between the independent contributions of CTLA-4 blockade in cis and in trans to antitumor activity, illustrating that both T_eff and T reg cells are relevant targets for the therapeutic efficacy of anti–CTLA-4 antibodies.     

Business resilience: Reframing healthcare risk management

The responsibility of risk management in healthcare is fractured, with multiple stakeholders. Most hospitals and healthcare systems do not have a fully integrated risk management system that spans the entire organizational and operational structure for the delivery of key services. This article provides insight toward utilizing a comprehensive Business Resilience program and associated methodology to understand and manage organizational risk leading to organizational effectiveness and operational efficiencies, with the fringe benefit of realizing sustainable operational capability during adverse conditions.     

Disease and gender-specific dysregulation of NGAL and MMP-9 in type 1 diabetes mellitus

Neutrophil gelatinase-associated lipocalin (NGAL), a biomarker of renal injury, can bind matrix metalloproteinase-9 (MMP-9) and inhibit its degradation, thereby sustaining MMP-9 proteolytic activity. MMP-9 is produced by renal podocytes, and podocyte MMP production can be modified by high ambient glucose levels. Moreover, dysregulation of MMP-9 activity, gene expression, or urine concentrations has been demonstrated in T2DM-associated nephropathy and in non-diabetic proteinuric renal diseases. Our objective was to determine whether NGAL/MMP-9 dysregulation might contribute to or serve as a biomarker of diabetic nephropathy in type 1 DM (T1DM). Plasma MMP-9, and urine NGAL and MMP-9 concentrations were measured in 121 T1DM and 55 control subjects and examined relative to indicators of glycemia, renal function, and degree of albuminuria. T1DM was associated with a significant increase in urinary excretion of both NGAL and MMP-9, and urine NGAL:Cr (NGAL corrected to urine creatinine) and urine MMP-9:Cr concentrations were highly correlated with each other. Both were also positively correlated with measurements of glycemic control and with albuminuria. Plasma MMP-9, urine MMP-9, and urine NGAL concentrations were significantly higher in females compared to males, and urine MMP-9:Cr concentrations displayed a menstrual cycle specific pattern. Increased urinary excretion of NGAL and MMP-9 supports a role for NGAL/MMP-9 dysregulation in renal dysfunction; moreover, gender-specific differences could support a gender contribution to pathological mechanisms or susceptibility for the development of renal complications in diabetes mellitus.