Assessment of Nocturnal Blood Pressure: Importance of Determining the Time in Bed-A Pilot Study.

Objectives: Nocturnal blood pressure (BP) monitoring is essential for evaluating cardiovascular risk and guiding treatment decisions. However, the standardized narrow-fixed nighttime period between 10 p.m. and 6 a.m. may not accurately reflect individual sleep schedules. This pilot study aimed to investigate the comparability between the standardized nighttime period and actual time in bed (TIB) regarding BP assessment. Further, our goal was to evaluate the clinical relevance of the observed BP differences. Methods: A total of 30 participants underwent 24 h ambulatory blood pressure monitoring (ABPM). Patient-specific TIB was precisely assessed through an accelerometer and a position sensor from the SOMNOtouch NIBP™ (SOMNOmedics GmbH, Randersacker, Germany). We analysed the effect of considering individual TIB as nighttime instead of the conventional narrow-fixed interval on the resulting nocturnal BP levels and dipping patterns. Results: We observed differences in both systolic and diastolic BP between the standardized nighttime period and the TIB. Furthermore, a notable percentage of patients (27%) changed their dipping pattern classification as a function of the nighttime definition adopted. We found strong correlations between the start (r = 0.75, p < 0.01), as well as the duration (r = -0.42, p = 0.02) of TIB and the changes in dipping pattern classification. Conclusions: Definition of nocturnal period based on the individual TIB leads to clinically relevant changes of nocturnal BP and dipping pattern classifications. TIB is easily detected using a body position sensor and accelerometer. This approach may thus improve the accuracy of cardiovascular risk evaluation and enhance treatment strategies.

Simultaneous 24-h ambulatory blood pressure measurement on both arms: a consideration for improving hypertension management.

OBJECTIVE: Arterial hypertension is one of the common treatment goals in today's medicine. 24-h ambulatory blood pressure measurement (ABPM) performed by oscillometric cuff-based devices is considered as the gold standard in hypertension diagnostics. This study aims at examining the measurement accuracy of a widely used, ABPM device. METHODS: Fifty-two young and healthy participants underwent simultaneous 24-h ABPM on the left and the right upper arm using two Boso/A&D TM-2430 oscillometric cuff-based devices. Pressure curves of the cuffs, as well as hydrostatic pressure difference between the cuffs were recorded. RESULTS: The mean differences between both simultaneous measurements were 1.16 mmHg with limits of agreement of 36.23 mmHg for SBP and 1.32 mmHg with limits of agreement of 32.65 mmHg for DBP. Excluding measurements where the pressure curves were disturbed and correcting for hydrostatic pressure difference between the cuffs, reduced the measurement error. However, limits of agreement remained around 20 mmHg. There were large differences in hypertension grading and dipping pattern classification between simultaneous measurements on the left and right arm. CONCLUSION: The cuff-based ABPM device reveals notable measurement uncertainties, influencing hypertension grading, dipping pattern classification and blood pressure variability. These effects are attributed in part to disturbances during cuff deflation and hydrostatic influences. Nonetheless, ABPM has shown its clinical values in several studies, while this study underscores its still unlocked potential to improve hypertension management.

Studies on the Effects of Hypercholesterolemia on Mouse Ophthalmic Artery Reactivity.

Atherogenic lipoproteins may impair vascular reactivity, leading to tissue damage in various organs, including the eye. This study aimed to investigate whether ophthalmic artery reactivity is affected in mice lacking the apolipoprotein E gene (ApoE-/-), a model for hypercholesterolemia and atherosclerosis. Twelve-month-old male ApoE-/- mice and age-matched wild-type controls were used to assess vascular reactivity using videomicroscopy. Moreover, the vascular mechanics, lipid content, levels of reactive oxygen species (ROS), and expression of pro-oxidant redox enzymes and the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) were determined in vascular tissue. Unlike the aorta, the ophthalmic artery of ApoE-/- mice developed no signs of endothelial dysfunction and no signs of excessive lipid deposition. Remarkably, the levels of ROS, nicotinamide adenine dinucleotide phosphate oxidase 1 (NOX1), NOX2, NOX4, and LOX-1 were increased in the aorta but not in the ophthalmic artery of ApoE-/- mice. Our findings suggest that ApoE-/- mice develop endothelial dysfunction in the aorta by increased oxidative stress via the involvement of LOX-1, NOX1, and NOX2, whereas NOX4 may participate in media remodeling. In contrast, the ophthalmic artery appears to be resistant to chronic apolipoprotein E deficiency. A lack of LOX-1 expression/overexpression in response to increased oxidized low-density lipoprotein levels may be a possible mechanism of action.

Comparison of Prognostic Models for Functional Outcome in Aneurysmal Subarachnoid Hemorrhage Based on Machine Learning.

BACKGROUND: Controversy exists regarding the superiority of the performance of prognostic tools based on advanced machine learning (ML) algorithms for patients with aneurysmal subarachnoid hemorrhage (aSAH). However, it is unclear whether ML prognostic models will benefit patients due to the lack of a comprehensive assessment. We aimed to develop and evaluate ML models for predicting unfavorable functional outcomes for aSAH patients and identify the model with the greatest performance. METHODS: In this retrospective study, a dataset of 955 patients with aSAH was used to construct and validate prognostic models for functional outcomes assessed using the modified Rankin scale during a follow-up period of 3-6 months. Clinical scores and clinical and radiological features on admission and secondary complications were used to construct models based on 5 ML algorithms (i.e., logistic regression [LR], k-nearest neighbor, extreme gradient boosting, random forest, and artificial neural network). For evaluation among the models, the area under the receiver operating characteristic curve, area under the precision-recall curve, calibration curve, and decision curve analysis were used. RESULTS: Composite models had significantly higher area under the receiver operating characteristic curves than did simple models in predicting unfavorable functional outcomes. Compared with other composite models (random forest and extreme gradient boosting) with good calibration, LR had the highest area under the precision-recall score and showed the greatest benefit in decision curve analysis. CONCLUSIONS: Of the 5 studied ML models, the conventional LR model outperformed the advanced algorithms in predicting the prognosis and could be a useful tool for health care professionals.

Accuracy of cuff-less, continuous, and non-invasive blood pressure measurement in 24-h ABPM in children aged 5-17.

PURPOSE: Ambulatory, cuff-less blood pressure (BP) measurement devices are a promising trend to alleviate the strains of conventional, cuff-based BP determination. Cuff-less devices circumvent discomfort and nocturnal arousal reactions which can be triggered by cuff inflation from conventional, cuff-based ambulatory blood pressure measurement devices. Mitigating these discomforts is especially desirable when performing measurement in children. In this study we want to assess the clinical validity of a cuff-less BP measurement device for 24-h measurements in children and adolescents. MATERIALS AND METHODS: We compared the simultaneously retrieved BP data of the cuff-less SOMNOtouch NIBP and the cuff-based Mobil-O-Graph in 24-h use in 90 children in the range from 5 to 17 years old. RESULTS: A total of 1218 valid measurement pairs showed a mean deviation of 0.99 mmHg (limits of agreement: 21.44/-19.46) for systolic and 3.03 mmHg (limits of agreement: 24.37/-18.31) for diastolic BP values. Patient-specific difference of means was within 15 mmHg in 97.7% (systolic BP) and 93.2% (diastolic BP) patients. 25.6% of nocturnal cuff inflations led to determinable, BP-relevant arousal reactions. CONCLUSIONS: The SOMNOtouch NIBP demonstrated little measurement deviation of mean BP compared to the cuff-based technique over a broad spectrum of 24-h, ambulatory BP measurements in children and adolescents. Cuff-less blood pressure measurement relieves the issue of nocturnal arousal reactions which are shown to be frequently induced by cuff-based measurements. Driven by these promising results, we encourage ongoing efforts to create enough evidence on cuff-less BP measurement to promote it into broad clinical application.

What is known about the topic?Hypertension is of increasing relevance in children and adolescentsBlood pressure measurement is difficult, especially in younger individualsWhat this study adds?The study investigated the accuracy of a cuff-less blood pressure (BP) measurement device, SOMNOtouch™ NIBP, in children and adolescents for 24-h measurements, in comparison to a traditional cuff-based device.The experiment involved 90 participants aged between 5 and 17 years old, with both devices worn simultaneously for 24 h.The results indicated that the cuff-less device showed a minor average deviation in BP measurements. The mean deviation for systolic and diastolic BP values was 0.99 mmHg and 3.03 mmHg, respectively.About 25.6% of night-time cuff inflations in traditional devices led to significant arousal reactions.The study concluded that the cuff-less device had a slight measurement deviation and could alleviate issues like nocturnal arousal reactions that are common with cuff-based devices.These findings suggest the potential for broad clinical application of cuff-less BP measurement devices, especially in children and adolescents, to reduce discomfort and improve patient adherence. However, more research is needed to solidify these findings.

Piezo1 Mediates Vasodilation Induced by Acute Hyperglycemia in Mouse Renal Arteries and Microvessels.

BACKGROUND: Acute hyperglycemia is a risk factor for developing acute kidney injury and poor renal outcome in critically ill patients, whereby the role of renal vasculature remains unclear. We hypothesize that hyperglycemia-associated hyperosmolarity facilitates vasodilation through Piezo1-mediated eNOS (endothelial NO synthase) activation. METHODS: Vasoreactivity was analyzed using wire myography in isolated mouse mesenteric arteries and renal interlobar, and using microvascular perfusion in renal afferent arterioles and efferent arterioles, and vasa recta. Immunofluorescence and Western blot were used for molecular analyses of isolated mouse blood vessels and human umbilical vein endothelial cells. RESULTS: Pretreatment with hyperglycemia (44 mmol/L glucose; 4 hours) increased acetylcholine-induced relaxation in interlobar arteries and mesenteric arteries, which was prevented by eNOS inhibition using Nω-nitro-L-arginine methylester hydrochloride. Hyperosmotic mannitol solution had a similar effect. Hyperglycemia induced an immediate, Nω-nitro-L-arginine methylester hydrochloride-inhibitable dilation in afferent arterioles, efferent arterioles, and vasa recta, whereby stronger dilation in afferent arterioles compared to efferent arterioles. Hyperglycemia also increased glomerular filtration rate in mice. In human umbilical vein endothelial cells, hyperglycemia, and the Piezo1 activator Yoda-1 increased levels of Piezo1 protein, p-CaMKII (phosphorylated Ca2+/Calmodulin-dependent protein kinase type II), Akt (protein kinase B), and p-eNOS (phosphorylated eNOS). The hyperglycemia effect could be prevented by inhibiting Piezo1 using GsMTx4 (Grammostola spatulata mechanotoxin 4) and CaMKII using KN93 (N-[2-[[[3-(4-Chlorophenyl)-2-propenyl]-methylamino]-methyl]-phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulphonamide). Furthermore, in arteries and microvessels, inhibition of Piezo1 using GsMTx4 prevented the hyperglycemia -effect, while Yoda-1 caused relaxation and dilation, respectively. CONCLUSIONS: Results reveal that Piezo1 mediates renal vasodilation induced by hyperosmolarity in acute hyperglycemia. This mechanism may contribute to the pathogenesis of renal damage by acute hyperglycemia.

Dihydromyricetin attenuates cisplatin-induced acute kidney injury by reducing oxidative stress, inflammation and ferroptosis.

BACKGROUND: Cisplatin is effective against various types of cancers. However, its clinical application is limited owing to its adverse effects, especially acute kidney injury (AKI). Dihydromyricetin (DHM), a flavonoid derived from Ampelopsis grossedentata, has varied pharmacological activities. This research aimed to determine the molecular mechanism for cisplatin-induced AKI. METHODS: A murine model of cisplatin-induced AKI (22 mg/kg, I.P.) and a HK-2 cell model of cisplatin-induced damage (30 µM) were established to evaluate the protective function of DHM. Renal dysfunction markers, renal morphology and potential signaling pathways were investigated. RESULTS: DHM decreased the levels of renal function biomarkers (blood urea nitrogen and serum creatinine), mitigated renal morphological damage, and downregulated the protein levels of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin. It upregulated the expression levels of antioxidant enzymes (superoxide dismutase and catalase expression), nuclear factor-erythroid-2-related factor 2 (Nrf2) and its downstream proteins, including heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic (GCLC) and modulatory (GCLM) subunits, thus eventually reducing cisplatin-induced reactive oxygen species (ROS) production. Moreover, DHM partially inhibited the phosphorylation of the active fragments of caspase-8 and -3 and mitogen-activated protein kinase and restored glutathione peroxidase 4 expression, which attenuated renal apoptosis and ferroptosis in cisplatin-treated animals. DHM also mitigated the activation of NLRP3 inflammasome and nuclear factor (NF)-κB, attenuating the inflammatory response. In addition, it reduced cisplatin-induced HK-2 cell apoptosis and ROS production, both of which were blocked by the Nrf2 inhibitor ML385. CONCLUSIONS: DHM suppressed cisplatin-induced oxidative stress, inflammation and ferroptosis probably through regulating of Nrf2/HO-1, MAPK and NF-κB signaling pathways.

Validation of the ABPMpro ambulatory blood pressure monitor in the general population according to AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018).

OBJECTIVE: The objective of this study is to evaluate the accuracy of the oscillometric upper-arm device ABPMpro (SOMNOmedics) for ambulatory blood pressure measurement in the general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) Universal Standard (ISO 81060-2:2018) at rest and during dynamic exercise. METHODS: Subjects were recruited to fulfill the age, sex, blood pressure (BP) and cuff distribution criteria of the AAMI/ESH/ISO standard using the same arm sequential BP measurement method. Three appropriate cuff sizes (18-24, 24-34 and 34-46 cm) of the tested device were used for the arm-varying circumferences. The inflation and deflation measurement modes of the ABPMpro were investigated. RESULTS: For the general validation study, 100 subjects were recruited and 90 were analyzed. For validation criterion (1), the mean ± SD of the differences between ABPMpro and reference BP was 0.7 ± 7.3/-0.7 ± 5.8 mmHg (systolic/diastolic) for inflation and 1.4 ± 7.7/-0.6 ± 6.1 mmHg for deflation measurements. For criterion (2), the SD of the averaged BP differences per subject was 5.98/5.10 mmHg for inflation and 6.46/5.36 mmHg for deflation measurements, thereby passing the threshold. In the ambulatory validation study ( N = 36), the mean difference was -1.2 ± 7.9/ 2.4 ± 6.6 mmHg for inflation and -0.7 ± 7.6/3.1 ± 7.0 mmHg for deflation measurements. CONCLUSION: The ABPMpro device fulfilled the ISO 81060-2:2018 requirements in the general population and in the ambulatory setting and can therefore be recommended for clinical use.

The pre-ejection period is a highly stress dependent parameter of paramount importance for pulse-wave-velocity based applications.

Purpose: The pulse-wave-velocity, is used for indirect, cuff-less, continuous blood pressure estimation. It is commonly detected by measuring the time delay between a defined point in an ECG and the arrival of the peripheral pulse wave (e.g., oxygen saturation sensor). The period between electrical stimulation of the heart (ECG) and actual blood ejection from the heart is called the pre-ejection period (PEP). This study aims at characterizing the PEP under mental and physical stress with focus on its relations to other cardiovascular parameters such as heart rate and importance for blood pressure (BP) estimation. Methods: We measured the PEP in 71 young adults at rest, under mental (TSST) and physical stress (ergometer) via impedance-cardiography. Results: The PEP is highly dependent on mental and physical load. It is strongly correlated with indicators of sympathetic strain (p < 0.001). At rest (mean 104.5 ms), the PEP shows a high interindividual variability but small intraindividual variability. Mental stress decreases the PEP by 16% (mean 90.0 ms) while physical stress halves PEP (mean 53.9 ms). The PEP does correlate differently with heart rate under differing circumstances (rest: R 2 0.06, mental stress: R 2 0.29, physical stress: R 2 0.65). Subsequently, using PEP and heart rate enables the discrimination of rest, mental and physical strain with a positive predictive value of 93%. Conclusion: The PEP is a cardiovascular parameter with large interindividual variability at rest and subject-depended dynamic under load which is of great importance for ECG-based pulse-wave-velocity (PWV) determination. Considering its variability and large impact on the pulse arrival time, PEP is a crucial factor in PWV based BP estimation.

Sulodexide Prevents Hyperglycemia-Induced Endothelial Dysfunction and Oxidative Stress in Porcine Retinal Arterioles.

Diabetes mellitus may cause severe damage to retinal blood vessels. The central aim of this study was to test the hypothesis that sulodexide, a mixture of glycosaminoglycans, has a protective effect against hyperglycemia-induced endothelial dysfunction in the retina. Functional studies were performed in isolated porcine retinal arterioles. Vessels were cannulated and incubated with highly concentrated glucose solution (HG, 25 mM D-glucose) +/- sulodexide (50/5/0.5 µg/mL) or normally concentrated glucose solution (NG, 5.5 mM D-glucose) +/- sulodexide for two hours. Endothelium-dependent and endothelium-independent vasodilatation were measured by videomicroscopy. Reactive oxygen species (ROS) were quantified by dihydroethidium (DHE) fluorescence. Using high-pressure liquid chromatography (HPLC), the intrinsic antioxidant properties of sulodexide were investigated. Quantitative PCR was used to determine mRNA expression of regulatory, inflammatory, and redox genes in retinal arterioles, some of which were subsequently quantified at the protein level by immunofluorescence microscopy. Incubation of retinal arterioles with HG caused significant impairment of endothelium-dependent vasodilation, whereas endothelium-independent responses were not affected. In the HG group, ROS formation was markedly increased in the vascular wall. Strikingly, sulodexide had a protective effect against hyperglycemia-induced ROS formation in the vascular wall and had a concentration-dependent protective effect against endothelial dysfunction. Although sulodexide itself had only negligible antioxidant properties, it prevented hyperglycemia-induced overexpression of the pro-oxidant redox enzymes, NOX4 and NOX5. The data of the present study provide evidence that sulodexide has a protective effect against hyperglycemia-induced oxidative stress and endothelial dysfunction in porcine retinal arterioles, possibly by modulation of redox enzyme expression.

Impact of oscillometric measurement artefacts in ambulatory blood pressure monitoring on estimates of average blood pressure and of its variability: a pilot study.

OBJECTIVE: Ambulatory blood pressure monitoring (ABPM) plays an important role in the diagnosis of hypertension. However, methodological factors and the measurement conditions affect the results and may lead to incorrect classification of the patient. We performed a pilot study to evaluate the impact of oscillometric measurement artefacts on ABPM-derived variables. METHODS: Four classes of artefacts have been detected: motor activity artefacts, cuff errors, cardiovascular arousals, and arrhythmias. The data consisted of uncorrected measurements (all data), corrected measurements (all artefact free data), and artefact affected data. RESULTS: A total of 30 individuals (9 female/21 male), aged between 36 and 86 years, mean: 65.5 (standard deviation: 9.5) were included in the study. The average blood pressure (BP) was higher in artefacts-affected measurements compared the artefact-free measurements both for systolic (4.6 mmHg) and diastolic (1.3 mmHg) measurements. Further, artefact-affected systolic BP (SBP) was 6.4 mmHg higher than artefact-free measurements during daytime. Nocturnal measurements showed no artefact-depended differences. Individual comparisons yielded that 23% of the participants crossed the threshold for BP classification for either 24-h, daytime or nocturnal hypertension when comparing uncorrected and artefact-free measurements. Dipping classification changed within 24% of participants. BP variability was 21 and 12% higher for SPB and DBP, respectively, during daytime. These differences were even higher (27% for SBP and 21% for DPB) during night-time. CONCLUSION: The study reveals that measurement artefacts are frequently present during cuff-based ABPM and do relevantly affect measurement outcome. Exclusion of measurement artefacts is a promising approach to improving cuff-based ABPM accuracy.

Quantifying the impact of gut microbiota on inflammation and hypertensive organ damage.

AIMS: Hypertension (HTN) can lead to heart and kidney damage. The gut microbiota has been linked to HTN, although it is difficult to estimate its significance due to the variety of other features known to influence HTN. In the present study, we used germ-free (GF) and colonized (COL) littermate mice to quantify the impact of microbial colonization on organ damage in HTN. METHODS AND RESULTS: 4-week-old male GF C57BL/6J littermates were randomized to remain GF or receive microbial colonization. HTN was induced by subcutaneous infusion with angiotensin (Ang) II (1.44 mg/kg/day) and 1% NaCl in the drinking water; sham-treated mice served as control. Renal damage was exacerbated in GF mice, whereas cardiac damage was more comparable between COL and GF, suggesting that the kidney is more sensitive to microbial influence. Multivariate analysis revealed a larger effect of HTN in GF mice. Serum metabolomics demonstrated that the colonization status influences circulating metabolites relevant to HTN. Importantly, GF mice were deficient in anti-inflammatory faecal short-chain fatty acids (SCFA). Flow cytometry showed that the microbiome has an impact on the induction of anti-hypertensive myeloid-derived suppressor cells and pro-inflammatory Th17 cells in HTN. In vitro inducibility of Th17 cells was significantly higher for cells isolated from GF than conventionally raised mice. CONCLUSION: The microbial colonization status of mice had potent effects on their phenotypic response to a hypertensive stimulus, and the kidney is a highly microbiota-susceptible target organ in HTN. The magnitude of the pathogenic response in GF mice underscores the role of the microbiome in mediating inflammation in HTN.

Continuous cuffless and non-invasive measurement of arterial blood pressure-concepts and future perspectives.

Hypertension diagnosis is one of the most common and important procedures in everyday clinical practice. Its applicability depends on correct and comparable measurements. Cuff-based measurement paradigms have dominated ambulatory blood pressure (BP) measurements for multiple decades. Cuffless and non-invasive methods may offer various advantages, such as a continuous and undisturbing measurement character. This review presents a conceptual overview of recent advances in the field of cuffless measurement paradigms and possible future developments which would enable cuffless beat-to-beat BP estimation paradigms to become clinically viable. It was refrained from a direct comparison between most studies and focussed on a conceptual merger of the ideas and conclusions presented in landmark scientific literature. There are two main approaches to cuffless beat-to-beat BP estimation represented in the scientific literature: First, models based on the physiological understanding of the cardiovascular system, mostly reliant on the pulse wave velocity combined with additional parameters. Second, models based on Deep Learning techniques, which have already shown great performance in various other medical fields. This review wants to present the advantages and limitations of each approach. Following this, the conceptional idea of unifying the benefits of physiological understanding and Deep Learning techniques for beat-to-beat BP estimation is presented. This could lead to a generalised and uniform solution for cuffless beat-to-beat BP estimations. This would not only make them an attractive clinical complement or even alternative to conventional cuff-based measurement paradigms but would substantially change how we think about BP as a fundamental marker of cardiovascular medicine.

This concept review wants to highlight the current state of non-invasive cuffless continuous blood pressure estimation.Cuffless blood pressure measurement devices usually rely on pulse wave velocity.Pulse wave velocity is mostly calculated via measuring pulse arrival time.Using pulse transit time instead of pulse arrival time showed improved results.Additional biomarkers like heart rate, photoplethysmogram intensity ratio or heart rate power spectrum ratio can be used to improve measurement precision.For cuffless and cuff-based devices intended for 24-hour BP measurements, a more refined validation protocol is required.The ESH assesses the measurement accuracy of cuffless devices as unclear and does not recommend hypertension diagnosis based on cuffless devices.Machine Learning and Deep Learning applications are a powerful tool to generate complex algorithms, which can be used to estimate blood pressure.Selecting biomarkers like pulse wave velocity, heart rate, etc. as input features for Deep Learning systems would be a very promising approach to measure blood pressure more precise.

Tacrolimus Causes Hypertension by Increasing Vascular Contractility via RhoA (Ras Homolog Family Member A)/ROCK (Rho-Associated Protein Kinase) Pathway in Mice.

BACKGROUND: To provide tacrolimus is first-line treatment after liver and kidney transplantation. However, hypertension and nephrotoxicity are common tacrolimus side effects that limit its use. Although tacrolimus-related hypertension is well known, the underlying mechanisms are not. Here, we test whether tacrolimus-induced hypertension involves the RhoA (Ras homolog family member A)/ROCK (Rho-associated protein kinase) pathway in male C57Bl/6 mice. METHODS: Intra-arterial blood pressure was measured under anesthesia. The reactivity of renal afferent arterioles and mesenteric arteries were assessed in vitro using microperfusion and wire myography, respectively. RESULTS: Tacrolimus induced a transient rise in systolic arterial pressure that was blocked by the RhoA/ROCK inhibitor Fasudil (12.0±0.9 versus 3.2±0.7; P<0.001). Moreover, tacrolimus reduced the glomerular filtration rate, which was also prevented by Fasudil (187±20 versus 281±8.5; P<0.001). Interestingly, tacrolimus enhanced the sensitivity of afferent arterioles and mesenteric arteries to Ang II (angiotensin II), likely due to increased intracellular Ca2+ mobilization and sensitization. Fasudil prevented increased Ang II-sensitivity and blocked Ca2+ mobilization and sensitization. Preincubation of mouse aortic vascular smooth muscle cells with tacrolimus activated the RhoA/ROCK/MYPT-1 (myosin phosphatase targeting subunit 1) pathway. Further, tacrolimus increased cytoplasmic reactive oxygen species generation in afferent arterioles (107±5.9 versus 163±6.4; P<0.001) and in cultured mouse aortic vascular smooth muscle cells (100±7.5 versus 160±23.2; P<0.01). Finally, the reactive oxygen species scavenger Tempol inhibited tacrolimus-induced Ang II hypersensitivity in afferent arterioles and mesenteric arteries. CONCLUSIONS: The RhoA/ROCK pathway may play an important role in tacrolimus-induced hypertension by enhancing Ang II-specific vasoconstriction, and reactive oxygen species may participate in this process by activating the RhoA/ROCK pathway.

Nitric Oxide Signalling in Descending Vasa Recta after Hypoxia/Re-Oxygenation.

Reduced renal medullary oxygen supply is a key factor in the pathogenesis of acute kidney injury (AKI). As the medulla exclusively receives blood through descending vasa recta (DVR), dilating these microvessels after AKI may help in renoprotection by restoring renal medullary blood flow. We stimulated the NO-sGC-cGMP signalling pathway in DVR at three different levels before and after hypoxia/re-oxygenation (H/R). Rat DVR were isolated and perfused under isobaric conditions. The phosphodiesterase 5 (PDE5) inhibitor sildenafil (10-6 mol/L) impaired cGMP degradation and dilated DVR pre-constricted with angiotensin II (Ang II, 10-6 mol/L). Dilations by the soluble guanylyl cyclase (sGC) activator BAY 60-2770 as well as the nitric oxide donor sodium nitroprusside (SNP, 10-3 mol/L) were equally effective. Hypoxia (0.1% O2) augmented DVR constriction by Ang II, thus potentially aggravating tissue hypoxia. H/R left DVR unresponsive to sildenafil, yet sGC activation by BAY 60-2770 effectively dilated DVR. Dilation to SNP under H/R is delayed. In conclusion, H/R renders PDE5 inhibition ineffective in dilating the crucial vessels supplying the area at risk for hypoxic damage. Stimulating sGC appears to be the most effective in restoring renal medullary blood flow after H/R and may prove to be the best target for maintaining oxygenation to this vulnerable area of the kidney.

The B-Score is a novel metric for measuring the true performance of blood pressure estimation models.

We aimed to develop and test a novel metric for the relative performance of blood pressure estimation systems (B-Score). The B-Score sets absolute blood pressure estimation model performance in contrast to the dataset the model is tested upon. We calculate the B-Score based on inter- and intrapersonal variabilities within the dataset. To test the B-Score for reliable results and desired properties, we designed generic datasets with differing inter- and intrapersonal blood pressure variability. We then tested the B-Score's real-world functionality with a small, published dataset and the largest available blood pressure dataset (MIMIC IV). The B-Score demonstrated reliable and desired properties. The real-world test provided allowed the direct comparison of different datasets and revealed insights hidden from absolute performance measures. The B-Score is a functional, novel, and easy to interpret measure of relative blood pressure estimation system performance. It is easily calculated for any dataset and enables the direct comparison of various systems tested on different datasets. We created a metric for direct blood pressure estimation system performance. The B-Score allows researchers to detect promising trends quickly and reliably in the scientific literature. It further allows researchers and engineers to quickly assess and compare performances of various systems and algorithms, even when tested on different datasets.

ZIP14 is involved in iron deposition and triggers ferroptosis in diabetic nephropathy.

Ferroptosis is caused by lipid peroxidation and iron accumulation and can cause cell death. Abnormally expressed iron transporters are involved in ferroptosis in a variety of diseases. ZRT/IRT-like protein 14 (ZIP14) is a transport protein that can mediate cellular uptake of iron, zinc, and manganese. Herein, we have tested the hypothesis that the divalent metal transporter ZIP14 is involved in the initiation of ferroptosis in diabetic nephropathy (DN). DN was induced in 8-week-old male rats by streptozotocin before analysis of the degree of renal tubular injury. In addition, an in vitro model of DN in human kidney proximal tubular cell line was used. We showed that ZIP14 was up-regulated and ferrous iron (Fe2+) levels increased both in vivo and in vitro. Expression of glutathione peroxidase 4 and the level of glutathione were reduced, whereas that of malondialdehyde (MDA) increased. Ferrostatin-1 (Fer-1) treatment reduced the expression of ZIP14 and the levels of Fe2+ and MDA, which is consistent with ferroptosis. Fer-1 improved kidney function in DN rats. This was characterized by urine levels of protein-to-creatinine ratio, α1-microglobulin, and N-acetyl-ß-D-glucosaminidase. Our study demonstrates a novel role for ZIP14 in diabetic kidney injury mediated by ferroptosis, and suggests a potential new therapeutic approach for the treatment of diabetic nephropathy.

rhADAMTS13 reduces oxidative stress by cleaving VWF in ischaemia/reperfusion-induced acute kidney injury.

AIMS: Acute kidney injury (AKI), a major health burden, lacks effective therapy. Anti-inflammatory actions of a disintegrin and metalloproteinase with a thrombospondin type 1 motif member 13 (ADAMTS13) may provide a new treatment option for AKI. Along with inflammation, oxidative stress is critical for AKI development, yet the impact of ADAMTS13 on oxidative stress in AKI remains to be fully elucidated. METHODS: We assess recombinant human ADAMTS13 (rhADAMTS13) actions on oxidative stress in a murine ischaemia/reperfusion (IR) model. Antioxidant stress-enzyme activities, renal morphology, kidney function markers and vascular function of isolated afferent arterioles are quantified. RESULTS: rhADAMTS13 provided after IR, reduces blood urea nitrogen (BUN) by 33% and serum creatinine (Scr) by 73% in 24 hours post-IR. rhADAMTS13 reduces BUN (40.03 ± 20.34 mmol/L vs 72.35 ± 18.74 mmol/L, P < .01), Scr (75.67 ± 51.19 µmol/L vs 176.17 ± 55.38 µmol/L, P < .01) and proteinuria by 41% in 48 hours post-IR as well. Moreover, rhADAMTS13 administration decreases malondialdehyde (MDA) and increases the activity of antioxidant stress enzymes, and attenuates reactive oxygen species production. rhADAMTS13 also upregulates nuclear factor-erythroid-2-related factor 2/haem oxygenase-1, enhances antioxidant enzymes activity and alleviates endothelial dysfunction. Finally, treatment with rhADAMTS13 mitigates severe functional and morphological injury present in IR mice. Extracellular signal-regulated kinase (ERK) phosphorylation is limited by rhADAMTS13 and PPARγ expression is partly restored in ischaemic kidneys. Co-administration of von Willebrand factor (VWF) impairs rhADAMTS13's antioxidant capacity and its protective role in IR. CONCLUSION: rhADAMTS13 alleviates renal IR injury through antioxidant effects by cleaving VWF.

Novel soluble guanylyl cyclase activators increase glomerular cGMP, induce vasodilation and improve blood flow in the murine kidney.

BACKGROUND AND PURPOSE: Generation of cGMP via NO-sensitive soluble guanylyl cyclase (sGC) has been implicated in the regulation of renal functions. Chronic kidney disease (CKD) is associated with decreased NO bioavailability, increased oxidative stress and oxidation of sGC to its haem-free form, apo-sGC. Apo-sGC cannot be activated by NO, resulting in impaired cGMP signalling that is associated with chronic kidney disease progression. We hypothesised that sGC activators, which activate apo-sGC independently of NO, increase renal cGMP production under conditions of oxidative stress, thereby improving renal blood flow (RBF) and kidney function. EXPERIMENTAL APPROACH: Two novel sGC activators, runcaciguat and BAY-543, were tested on murine kidney. We measured cGMP levels in real time in kidney slices of cGMP sensor mice, vasodilation of pre-constricted glomerular arterioles and RBF in isolated perfused kidneys. Experiments were performed at baseline conditions, under L-NAME-induced NO deficiency, and in the presence of oxidative stress induced by ODQ. KEY RESULTS: Mouse glomeruli showed NO-induced cGMP increases. Under baseline conditions, sGC activator did not alter glomerular cGMP concentration or NO-induced cGMP generation. In the presence of ODQ, NO-induced glomerular cGMP signals were markedly reduced, whereas sGC activator induced strong cGMP increases. L-NAME and ODQ pretreated isolated glomerular arterioles were strongly dilated by sGC activator. sGC activator also increased cGMP and RBF in ODQ-perfused kidneys. CONCLUSION AND IMPLICATION: sGC activators increase glomerular cGMP, dilate glomerular arterioles and improve RBF under disease-relevant oxidative stress conditions. Therefore, sGC activators represent a promising class of drugs for chronic kidney disease treatment. LINKED ARTICLES: This article is part of a themed issue on cGMP Signalling in Cell Growth and Survival. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.11/issuetoc.