Concise report: a minimal-invasive method to retrieve and identify entheseal tissue from psoriatic arthritis patients.

OBJECTIVES: To establish a minimally invasive biopsy technique for the analysis of entheseal tissue in patients with psoriatic arthritis (PsA). METHODS: Human cadavers were used for establishing the technique to retrieve tissue from the lateral humeral epicondyle enthesis (cadaveric biopsies). After biopsy, the entire enthesis was surgically resected (cadaveric resections). Biopsies and resections were assessed by label-free second harmonic generation (SHG) microscopy. The same technique was then applied in patients with PsA with definition of entheseal tissue by SHG, staining of CD45+immune cells and RNA extraction. RESULTS: Entheseal biopsies from five cadavers allowed the retrieval of entheseal tissue as validated by the analysis of resection material. Microscopy of biopsy and resection sections allowed differentiation of entheseal, tendon and muscle tissue by SHG and definition of specific intensity thresholds for entheseal tissue. In subsequent entheseal biopsies of 10 PsA patients: the fraction of entheseal tissue was high (65%) and comparable to cadaveric biopsies (68%) as assessed by SHG microscopy. Furthermore, PsA biopsies showed immune cell infiltration and sufficient retrieval of RNA for further molecular analysis. CONCLUSION: Entheseal biopsy of the lateral epicondyle is feasible in patients with PsA allowing reliable retrieval of entheseal tissue and its identification by SHG microscopy.

Laboratory Evaluation of Linearity, Repeatability, and Hematocrit Interference With an Internet-Enabled Blood Glucose Meter.

BACKGROUND: In recent clinical trials, use of the MyGlucoHealth blood glucose meter (BGM) and electronic diary was associated with an unusual reporting pattern of glycemic data and hypoglycemic events. Therefore, the performance of representative BGMs used by the patients was investigated to assess repeatability, linearity, and hematocrit interference in accordance with regulatory guidelines. METHOD: Ten devices and 6 strip lots were selected using standard randomization and repeatability procedures. Venous heparinized blood was drawn from healthy subjects, immediately aliquoted and adjusted to 5 target blood glucose (BG) ranges for the repeatability and 11 BG concentrations for the linearity tests. For the hematocrit interference test, each sample within 5 target BG ranges was split into 5 aliquots and adjusted to hematocrit levels across the acceptance range. YSI 2300 STAT Plus was used as the laboratory reference method in all experiments. RESULTS: Measurement repeatability or precision was acceptable across the target BG ranges for all devices and strip lots with coefficient of variation (CV) between 3.4-9.7% (mean: 5.7%). Linearity was shown by a correlation coefficient of .991; however, a positive bias was seen for BG <100 mg/dL (86% measurements did not meet ISO15197:2015 acceptance criteria). Significant hematocrit interference (up to 20%) was observed for BG >100 mg/dL (ISO15197:2015 acceptance criteria: ±10%), while the results were acceptable for BG <100 mg/dL. CONCLUSIONS: The BGM met repeatability requirements but demonstrated a significant measurement bias in the low BG range. In addition, it failed the ISO15197:2015 criteria for hematocrit interference.