Evaluation of System Accuracy, Precision, Hematocrit Influence, and User Performance of Two Blood Glucose Monitoring Systems Based on ISO 15197:2013/EN ISO 15197:2015.

INTRODUCTION: Sufficiently high analytical quality of blood glucose monitoring systems (BGMS) is a prerequisite for efficient diabetes therapy. In this study we assessed system accuracy, measurement repeatability, intermediate measurement precision, user performance, and the influence of hematocrit on two CE-marked blood glucose monitoring systems. For one BGMS, measurement accuracy using venous samples was additionally investigated. METHODS: Study procedures were based on the International Organization of Standardization (ISO) 15197:2013/EN ISO 15197:2015 ("ISO 15197"). User performance included data from 100 subjects who used one test strip lot, whereas for all other analyses three different reagent system lots were used. For system accuracy assessment, 100 capillary samples were measured in duplicate with each of three reagent system lots per system, resulting in 600 results per system. RESULTS: CareSens S Fit and CareSens H Beat both fulfilled the ISO 15197 accuracy criteria with 97.5-100% of each test strip lot's results falling within ± 15 mg/dL or ± 15% of the results of the comparison method and 100% of results in consensus error grid (CEG) zone A for all three lots. User performance evaluation revealed sufficient accuracy in the hands of lay users although some handling errors were documented by study staff. Assessment of measurement repeatability and intermediate measurement precision is given by standard deviation (SD) (glucose levels < 100 mg/dL) and by coefficient of variation (CV) (glucose concentrations ≥ 100 mg/dL). SD was ≤ 4.1 mg/dL and CV ≤ 4.2% for measurement repeatability and SD was ≤ 2.2 mg/dL and CV ≤ 2.6% for intermediate measurement precision. In case of hematocrit influence, both BGMS complied with all three tested lots with the defined criteria. CONCLUSION: Both BGMS analyzed in this study fulfilled the required accuracy criteria of ISO 15197. They showed high precision, good performance in the hands of lay users, and the influence of hematocrit was acceptable in the labeled range.

Clinical Performance Evaluation of Continuous Glucose Monitoring Systems: A Scoping Review and Recommendations for Reporting.

The use of different approaches for design and results presentation of studies for the clinical performance evaluation of continuous glucose monitoring (CGM) systems has long been recognized as a major challenge in comparing their results. However, a comprehensive characterization of the variability in study designs is currently unavailable. This article presents a scoping review of clinical CGM performance evaluations published between 2002 and 2022. Specifically, this review quantifies the prevalence of numerous options associated with various aspects of study design, including subject population, comparator (reference) method selection, testing procedures, and statistical accuracy evaluation. We found that there is a large variability in nearly all of those aspects and, in particular, in the characteristics of the comparator measurements. Furthermore, these characteristics as well as other crucial aspects of study design are often not reported in sufficient detail to allow an informed interpretation of study results. We therefore provide recommendations for reporting the general study design, CGM system use, comparator measurement approach, testing procedures, and data analysis/statistical performance evaluation. Additionally, this review aims to serve as a foundation for the development of a standardized CGM performance evaluation procedure, thereby supporting the goals and objectives of the Working Group on CGM established by the Scientific Division of the International Federation of Clinical Chemistry and Laboratory Medicine.

Toll like-receptor agonist Pam3Cys modulates the immunogenicity of liposomes containing the tuberculosis vaccine candidate H56.

A major roadblock in the development of novel vaccines is the formulation and delivery of the antigen. Liposomes composed of a dimethyldioctadecylammonium (DDA) backbone and the adjuvant trehalose-6-6-dibehenate (TDB, termed "cationic adjuvant formulation (CAF01)", promote immunogenicity and protective efficacy of vaccines, most notably against infection with Mycobacterium tuberculosis. Specifically, the multicomponent antigen H56 delivered by CAF01 protects against tuberculosis in mice. Here we investigated whether the inclusion of immune-modulatory adjuvants into CAF01 modulates the immunogenicity of H56/CAF01 in vitro and in vivo. Based on our recent findings we selected the active sequence of the mycobacterial 19 kDa lipoprotein, Pam3Cys, which interacts with Toll like receptor 2 to induce an antimicrobial pathway. H56/CAF01-Pam3Cys liposomes were characterized for Pam3Cys incorporation, size, toxicity and activation of primary human macrophages. Macrophages efficiently take up H56/CAF01-Pam3Cys and trigger the release of significantly higher levels of TNF, IL-12 and IL-10 than H56/CAF01 alone. To evaluate the immunogenicity in vivo, we immunized mice with H56/CAF01-Pam3Cys and measured the release of IFN-γ and IL-17A by lymph node cells and spleen cells. While the antigen-specific production of IFN-γ was reduced by inclusion of Pam3Cys into H56/CAF01, the levels of IL-17A remained unchanged. In agreement with this finding, the concentration of the IFN-γ-associated IgG2a antibodies in the serum was lower than in H56/CAF01 immunized animals. These results provide proof of concept that Toll like-receptor agonist can be included into liposomes to modulate immune responses. The discordant results between the in vitro studies with human macrophages and in vivo studies in mice highlight the relevance and complexity of comparing immune responses in different species.

The tyrosine kinase inhibitor dasatinib reduces the growth of intracellular Mycobacterium tuberculosis despite impairing T-cell function.

Tyrosine kinases are checkpoints for multiple cellular pathways and dysregulation induces malignancies, most notably chronic myeloid leukemia (CML). Inhibition of Abl-tyrosine kinases has evolved as a new concept for the treatment of CML and other malignant diseases. Due to the multiple immune-modulatory pathways controlled by tyrosine kinases, treatment with tyrosine kinase inhibitors (TKIs) will not only affect the biology of malignant cells but also modulate physiological immune functions. To understand the effects of TKIs on host defense against intracellular bacteria, we investigated the immunological impact of the dual Abl/Src TKI dasatinib on the cellular immune response to Mycobacterium tuberculosis (Mtb). Our results demonstrate that dasatinib impaired proliferation, cytokine release (IFN-γ, TNF-α, GM-CSF), expression of granulysin and degranulation of cytotoxic effector molecules of human Mtb-specific T-lymphocytes by inhibition of lymphocyte-specific protein tyrosine kinase (Lck) phosphorylation. Despite this profound inhibition of T-cell function, dasatinib suppressed growth of virulent Mtb in human macrophages co-cultured with autologous Mtb-specific T-cells (49±15%). Functional analysis suggested that growth inhibition is due to dasatinib-triggered lysosomal acidification in Mtb-infected macrophages. These results highlight the significance of innate immune responses, i.e. acidification of lysosomes, which control the multiplication of intracellular bacteria despite the lack of efficient T-cell support.