Classifying the diagnosis of study participants in clinical trials: a structured and efficient approach.

BACKGROUND: A challenge in imaging research is a diagnostic classification of study participants. We hypothesised that a structured approach would be efficient and that classification by medical students, residents, and an expert panel whenever necessary would be as valid as classification of all patients by experts. METHODS: OPTIMACT is a randomised trial designed to evaluate the effectiveness of replacing chest x-ray for ultra-low-dose chest computed tomography (CT) at the emergency department. We developed a handbook with diagnostic guidelines and randomly selected 240 cases from 2,418 participants enrolled in OPTIMACT. Each case was independently classified by two medical students and, if they disagreed, by the students and a resident in a consensus meeting. Cases without consensus and cases classified as complex were assessed by a panel of medical specialists. To evaluate the validity, 60 randomly selected cases not referred to the panel by the students and the residents were reassessed by the specialists. RESULTS: Overall, the students and, if necessary, residents were able to assign a diagnosis in 183 of the 240 cases (76% concordance; 95% confidence interval [CI] 71-82%). We observed agreement between students and residents versus medical specialists in 50/60 cases (83% concordance; 95% CI 74-93%). CONCLUSIONS: A structured approach in which study participants are assigned diagnostic labels by assessors with increasing levels of medical experience was an efficient and valid classification method, limiting the workload for medical specialists. We presented a viable option for classifying study participants in large-scale imaging trials (Netherlands National Trial Register number NTR6163).

Local Mast Cell Activation Promotes Neovascularization.

Mast cells have been associated with arteriogenesis and collateral formation. In advanced human atherosclerotic plaques, mast cells have been shown to colocalize with plaque neovessels, and mast cells have also been associated with tumor vascularization. Based on these associations, we hypothesize that mast cells promote angiogenesis during ischemia. In human ischemic muscle tissue from patients with end-stage peripheral artery disease, we observed activated mast cells, predominantly located around capillaries. Also, in mouse ischemic muscles, mast cells were detected during the revascularization process and interestingly, mast cell activation status was enhanced up to 10 days after ischemia induction. To determine whether mast cells contribute to both arteriogenesis and angiogenesis, mast cells were locally activated immediately upon hind limb ischemia in C57Bl/6 mice. At day 9, we observed a 3-fold increase in activated mast cell numbers in the inguinal lymph nodes. This was accompanied by an increase in the amount of Ly6Chigh inflammatory monocytes. Interestingly, local mast cell activation increased blood flow through the hind limb (46% at day 9) compared to that in non-activated control mice. Histological analysis of the muscle tissue revealed that mast cell activation did not affect the number of collaterals, but increased the collateral diameter, as well as the number of CD31+ capillaries. Together, these data illustrate that locally activated mast cell contribute to arteriogenesis and angiogenesis.

Disruption of a CD1d-mediated interaction between mast cells and NKT cells aggravates atherosclerosis.

BACKGROUND AND AIMS: The development of atherosclerosis is tightly regulated by the innate and adaptive immune system. Communication between these two compartments occurs, among others, upon presentation of lipid antigens to the NKT cell population by CD1d-expressing antigen-presenting cells. Recent evidence states that also mast cells express CD1d and can directly communicate with NKT cells. However, no such relationship has been reported in atherosclerosis. Here, we aimed to elucidate in vivo the CD1d-mediated interaction between mast cells and NKT cells upon atherosclerosis progression. METHODS: We adoptively transferred CD1d-/- or control mast cells to mast cell-deficient apoE-/-KitW-sh/W-sh mice and subsequently placed the animals on a Western-type diet for 10 weeks. RESULTS: At the end of the Western-type diet period, the aortic root of CD1d-/- mast cell-reconstituted mice displayed increased plaque size, with less collagen deposition and higher intraplaque CD4+ T cells, as compared to control mice. In addition, T cells inside the aortic arch showed higher pro-inflammatory cytokine production in the form of IFNγ, TNFα and IL-17. Finally, T-bet expression was found elevated in both CD4+ and CD8+ circulating T cells. CONCLUSIONS: This study is the first to illustrate that disruption of the CD1d communication pathway between mast cells and NKT cells aggravates atherosclerosis, through a shift towards pro-inflammatory T cell responses. This ability of mast cell action during plaque progression sheds new light on their role in atherosclerosis.