Evaluation of the Omron HEM-907 automated blood pressure device: comparison with office and ambulatory blood pressure readings

Blood pressure (BP) measured in the clinic is subject to the white coat effect and does not always indicate the 'usual' BP. Ambulatory BP is the current gold standard, but remains inconvenient for routine use. Interest in automated BP, where the healthcare professional is absent from the examination room during BP measurement, is growing, as this reduces the white coat effect and yields BP values that are close to ambulatory readings. The aim of this study was to investigate how well automated office BP (AOBP), measured using the Omron HEM-907 device, compares with observed office BP (OOBP, healthcare professional remains in the examination room) and awake ambulatory BP (AABP) measurements. OOBP, AOBP and AABP were measured in 108 participants, with OOBP and AOBP measurements repeated 1 week later, following a standardised protocol. Average BP readings for visit one were 134 ± 18/77 ± 11 for OOBP, 131 ± 16/75 ± 11 for AOBP, and 133 ± 15/82 ± 12 for AABP. On both visits, automated readings were significantly lower than observed readings for both systolic and diastolic BP (P < 0.001 for both). Automated readings were also significantly lower than ambulatory readings, with a mean difference in systolic/diastolic BP of - 2 ± 11/- 7 ± 10 (P < 0.001 for both), with high correlations between the two modalities (r = 0.75 and r = 0.64, for systolic and diastolic BP, respectively, P < 0.001 for both). AOBP measured by the Omron HEM-907 is not associated with a white coat effect, unlike observed readings, and provides reproducible results and good correlations with ambulatory readings. Automated BP measured using the Omron HEM-907 is, therefore, a useful alternative to observed office readings.

A direct interaction between the sigma-1 receptor and the hERG voltage-gated K+ channel revealed by atomic force microscopy and homogeneous time-resolved fluorescence (HTRF®)

The sigma-1 receptor is an endoplasmic reticulum chaperone protein, widely expressed in central and peripheral tissues, which can translocate to the plasma membrane and modulate the function of various ion channels. The human ether-à-go-go-related gene encodes hERG, a cardiac voltage-gated K(+) channel that is abnormally expressed in many human cancers and is known to interact functionally with the sigma-1 receptor. Our aim was to investigate the nature of the interaction between the sigma-1 receptor and hERG. We show that the two proteins can be co-isolated from a detergent extract of stably transfected HEK-293 cells, consistent with a direct interaction between them. Atomic force microscopy imaging of the isolated protein confirmed the direct binding of the sigma-1 receptor to hERG monomers, dimers, and tetramers. hERG dimers and tetramers became both singly and doubly decorated by sigma-1 receptors; however, hERG monomers were only singly decorated. The distribution of angles between pairs of sigma-1 receptors bound to hERG tetramers had two peaks, at ∼90 and ∼180° in a ratio of ∼2:1, indicating that the sigma-1 receptor interacts with hERG with 4-fold symmetry. Homogeneous time-resolved fluorescence (HTRF®) allowed the detection of the interaction between the sigma-1 receptor and hERG within the plane of the plasma membrane. This interaction was resistant to sigma ligands, but was decreased in response to cholesterol depletion of the membrane. We suggest that the sigma-1 receptor may bind to hERG in the endoplasmic reticulum, aiding its assembly and trafficking to the plasma membrane.