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.

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.

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.

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.

Perioperative Dynamics of Intracranial B-waves of Blood Flow Velocity in the Basal Cerebral Arteries in Patients with Brain Arteriovenous Malformation.

Intracranial B-waves (8-30 mHz) of blood flow velocity (BFV) in the cerebral arteries are observed in various pathologies of the brain. Changes in B-waves of BFV in pathological arteriovenous shunting and "steal" syndrome remain poorly understood. The aim of this study was to evaluate the dynamics of the B-wave amplitude of BFV (BWA) in patients with an arteriovenous malformation (AVM) in the brain. In 38 such patients, cerebral autoregulation (CA) was assessed using a cuff test and transfer function analysis of the mean blood pressure (BP) and BFV in the basal cerebral arteries within the range of Mayer waves (80-120 mHz). BWA was calculated with spectral analysis. Reliable CA impairment was denoted on the AVM side as compared with the contralateral side prior to intervention. BWA was greater on the AVM side (4.5 ± 2.7 cm/s) than on the contralateral side (2.2 ± 1.4 cm/s, p < 0.05). After embolization, there was a reliable improvement (p < 0.05) in CA and a decrease in BWA on the AVM side (2.7 ± 1.8 cm/s). Thus, a considerable increase in BWA on the AVM side that is not induced by BP fluctuations may indicate additional compensation for blood flow under conditions of reduced perfusion pressure. This assumption is supported by a reduction in BWA after AVM embolization.

Muscarinic Acetylcholine Receptors in the Retina-Therapeutic Implications.

Muscarinic acetylcholine receptors (mAChRs) belong to the superfamily of G-protein-coupled receptors (GPCRs). The family of mAChRs is composed of five subtypes, M1, M2, M3, M4 and M5, which have distinct expression patterns and functions. In the eye and its adnexa, mAChRs are widely expressed and exert multiple functions, such as modulation of tear secretion, regulation of pupil size, modulation of intraocular pressure, participation in cell-to-cell signaling and modula-tion of vascular diameter in the retina. Due to this variety of functions, it is reasonable to assume that abnormalities in mAChR signaling may contribute to the development of various ocular diseases. On the other hand, mAChRs may offer an attractive therapeutic target to treat ocular diseases. Thus far, non-subtype-selective mAChR ligands have been used in ophthalmology to treat dry eye disease, myopia and glaucoma. However, these drugs were shown to cause various side-effects. Thus, the use of subtype-selective ligands would be useful to circumvent this problem. In this review, we give an overview on the localization and on the functional role of mAChR subtypes in the eye and its adnexa with a special focus on the retina. Moreover, we describe the pathophysiological role of mAChRs in retinal diseases and discuss potential therapeutic approaches.

Age Impairs Soluble Guanylyl Cyclase Function in Mouse Mesenteric Arteries.

Endothelial dysfunction (ED) comes with age, even without overt vessel damage such as that which occurs in atherosclerosis and diabetic vasculopathy. We hypothesized that aging would affect the downstream signalling of the endothelial nitric oxide (NO) system in the vascular smooth muscle (VSM). With this in mind, resistance mesenteric arteries were isolated from 13-week (juvenile) and 40-week-old (aged) mice and tested under isometric conditions using wire myography. Acetylcholine (ACh)-induced relaxation was reduced in aged as compared to juvenile vessels. Pretreatment with L-NAME, which inhibits nitrix oxide synthases (NOS), decreased ACh-mediated vasorelaxation, whereby differences in vasorelaxation between groups disappeared. Endothelium-independent vasorelaxation by the NO donor sodium nitroprusside (SNP) was similar in both groups; however, SNP bolus application (10-6 mol L-1) as well as soluble guanylyl cyclase (sGC) activation by runcaciguat (10-6 mol L-1) caused faster responses in juvenile vessels. This was accompanied by higher cGMP concentrations and a stronger response to the PDE5 inhibitor sildenafil in juvenile vessels. Mesenteric arteries and aortas did not reveal apparent histological differences between groups (van Gieson staining). The mRNA expression of the α1 and α2 subunits of sGC was lower in aged animals, as was PDE5 mRNA expression. In conclusion, vasorelaxation is compromised at an early age in mice even in the absence of histopathological alterations. Vascular smooth muscle sGC is a key element in aged vessel dysfunction.

ADAMTS13 protects mice against renal ischemia-reperfusion injury by reducing inflammation and improving endothelial function.

Acute kidney injury (AKI) is a serious condition without efficient therapeutic options. Recent studies have indicated that recombinant human a disintegrin and metalloprotease with thrombospondin motifs 13 (rhADAMTS13) provides protection against inflammation. Therefore, we hypothesized that ADAMTS13 might protect against AKI by reducing inflammation. Bilateral renal ischemia-reperfusion injury (I/R) was used as AKI models in this study. Prophylactic infusion of rhADAMTS13 was employed to investigate potential mechanisms of renal protection. Renal function, inflammation, and microvascular endothelial function were assessed after 24 h of reperfusion. Our results showed that I/R mice increased plasma von Willebrand factor levels but decreased ADAMTS13 expression. Administration of rhADAMTS13 to I/R mice recovered renal function, histological injury, and apoptosis. Renal inflammation was reduced by rhADAMTS13, accompanied with the downregulation of p38/extracellular signal-regulated protein kinase phosphorylation and cyclooxygenase-2 expression. rhADAMTS13 restored vasodilation in afferent arterioles in I/R mice. Furthermore, rhADAMTS13 treatment enhanced phosphorylation of Akt at Ser473 and eNOS at Ser1177. Administration of the Akt pathway inhibitor wortmannin reduced the protective effect of rhADAMTS13. Our conclusions are that treatment with rhADAMTS13 ameliorates renal I/R injury by reducing inflammation, tubular cell apoptosis, and improving microvascular endothelial dysfunction. rhADAMTS13 could be a promising strategy to treat AKI in clinical settings.

Responses of retinal arterioles and ciliary arteries in pigs with acute respiratory distress syndrome (ARDS).

Acute respiratory distress syndrome (ARDS) is a clinical syndrome of acute lung failure in critically sick patients, which severely compromises the function of multiple organs, including the brain. Although, the optic nerve and the retina are a part of the central nervous system, the effects of ARDS on these ocular structures are completely unknown. Thus, the major goal of this study was to test the hypothesis that ARDS affects vascular function in the eye. ARDS was induced in anesthetized pigs by intratracheal injection of lipopolysaccharide (LPS). Sham-treated animals served as controls. Pigs were monitored for 8 h and then sacrificed. Subsequently, retinal arterioles and short posterior ciliary arteries were isolated and cannulated with micropipettes to measure vascular responses by videomicroscopy. Levels of reactive oxygen species (ROS) were quantified in isolated vessels using dihydroethidium (DHE). Messenger RNA expression of hypoxic, inflammatory, prooxidative, and antioxidative genes was assessed by real-time PCR. When group-dependent differences in mRNA expression levels were found for a particular gene, immunostainings were conducted. Strikingly, responses to the endothelium-dependent vasodilator, bradykinin, were markedly impaired in retinal arterioles of LPS-treated pigs, but no differences were seen between ciliary arteries of LPS- and sham-treated animals. ROS levels were increased in retinal arterioles but not in ciliary arteries of LPS-treated pigs. Messenger RNA levels for HIF-1α, VEGF-A and NOX2 were markedly increased in retinal arterioles of LPS-treated pigs, whereas ciliary arteries had only negligible mRNA level changes. Pronounced immunoreactivity for HIF-1α, VEGF-A and NOX2 was seen in the endothelium of retinal arterioles from LPS-treated pigs. Histologically, massive edema was seen especially in the retinal nerve fiber layer of pigs treated with LPS. Our study provides the first evidence that ARDS induced by intratracheal LPS application evokes endothelial dysfunction in porcine retinal arterioles together with retinal edema, indicative of vascular leakage. In contrast, ciliary arteries appear to be resistant to intratracheal LPS application.

Periodic breathing in healthy young adults in normobaric hypoxia equivalent to 3500 m, 4500 m, and 5500 m altitude.

PURPOSE: The occurrence of periodic breathing (PB) at high altitude during sleep and the quality of sleep are individually different and influenced by multiple factors including sex. Although poor sleep quality at high altitude might not be directly linked to oxygen desaturations, the PB upsurge at high altitude leads to significant oscillations in oxygen saturation. METHODS: Thirty-three students were recruited. Participants were randomly assigned to three groups (A, B, C) sleeping one full night in a dormitory with normobaric hypoxia at a FIO2 of 14.29% (A), a FIO2 of 12.47% (B), or a FIO2 of 10.82% (C). Full polysomnography was performed in each participant. RESULTS: Mean total sleeping time decreased significantly with increasing hypoxia (p < 0.001). Respiratory events changed from central hypopneas to central apneas (CA) with increasing hypoxia: CA = 17.8%, 50.0%, 92.2% of AHI (37.96 events per hour (n/h), 68.55 n/h, 93.44 n/h). AHI (p = 0.014) and time duration of respiratory events (p = 0.003) were significantly different between sexes, both greater in men. REM sleep was reduced. CONCLUSIONS: Men tend to be more prone to PB in normobaric hypoxia. Further research should implicate a longer acclimatization period around simulated 4500 m in order to find out if the exponential increase in PB between 4500 m and 5500 m could be shifted to lower hypoxic levels, i.e., higher altitudes.

Short-Time Ocular Ischemia Induces Vascular Endothelial Dysfunction and Ganglion Cell Loss in the Pig Retina.

Visual impairment and blindness are often caused by retinal ischemia-reperfusion (I/R) injury. We aimed to characterize a new model of I/R in pigs, in which the intraocular pathways were not manipulated by invasive methods on the ocular system. After 12 min of ischemia followed by 20 h of reperfusion, reactivity of retinal arterioles was measured in vitro by video microscopy. Dihydroethidium (DHE) staining, qPCR, immunohistochemistry, quantification of neurons in the retinal ganglion cell layer, and histological examination was performed. Retinal arterioles of I/R-treated pigs displayed marked attenuation in response to the endothelium-dependent vasodilator, bradykinin, compared to sham-treated pigs. DHE staining intensity and messenger RNA levels for HIF-1α, VEGF-A, NOX2, and iNOS were elevated in retinal arterioles following I/R. Immunoreactivity to HIF-1α, VEGF-A, NOX2, and iNOS was enhanced in retinal arteriole endothelium after I/R. Moreover, I/R evoked a substantial decrease in Brn3a-positive retinal ganglion cells and noticeable retinal thickening. In conclusion, the results of the present study demonstrate that short-time ocular ischemia impairs endothelial function and integrity of retinal blood vessels and induces structural changes in the retina. HIF-1α, VEGF-A, iNOS, and NOX2-derived reactive oxygen species appear to be involved in the pathophysiology.

Hypoxia-reoxygenation enhances murine afferent arteriolar vasoconstriction by angiotensin II.

We tested the hypothesis that hypoxia-reoxygenation (H/R) augments vasoreactivity to angiotensin II (ANG II). In particular, we compared an in situ live kidney slice model with isolated afferent arterioles (C57Bl6 mice) to assess the impact of tubules on microvessel response. Hematoxylin and eosin staining was used to estimate slice viability. Arterioles in the slices were located by differential interference contrast microscopy, and responses to vasoactive substances were assessed. Cytosolic calcium transients and NADPH oxidase (NOX) mRNA expression were studied in isolated afferent arterioles. SOD activity was measured in live slices. Both experimental models were subjected to control and H/R treatment (60 min). Slices were further analyzed after 30-, 60-, and 90-min hypoxia followed by 10- or 20-min reoxygenation (H/R). H/R resulted in enhanced necrotic tissue damage compared with control conditions. To characterize the slice model, we applied ANG II (10-7 M), norepinephrine (NE; 10-5 M), endothelin-1 (ET-1; 10-7 M), and ATP (10-4 M), reducing the initial diameter to 44.5 ± 2.8, 50.0 ± 2.2, 45.3 ± 2.6, and 74.1 ± 1.8%, respectively. H/R significantly increased the ANG II response compared with control in live slices and in isolated afferent arterioles, although calcium transients remained similar. TEMPOL incubation prevented the H/R effect on ANG II responses. H/R significantly increased NOX2 mRNA expression in isolated arterioles. SOD activity was significantly decreased after H/R. Enhanced arteriolar responses after H/R occurred independently from the surrounding tissue, indicating no influence of tubules on vascular function in this model. The mechanism of increased ANG II response after H/R might be increased oxidative stress and increased calcium sensitivity of the contractile apparatus.

Enhanced Renal Afferent Arteriolar Reactive Oxygen Species and Contractility to Endothelin-1 Are Associated with Canonical Wnt Signaling in Diabetic Mice.

BACKGROUND/AIMS: Canonical Wnt signaling is involved in oxidative stress, vasculopathy and diabetes mellitus but its role in diabetic renal microvascular dysfunction is unclear. We tested the hypothesis that enhanced canonical Wnt signaling in renal afferent arterioles from diabetic mice increases reactive oxygen species (ROS) and contractions to endothelin-1 (ET-1). METHODS: Streptozotocin-induced diabetes or control C57Bl/6 mice received vehicle or sulindac (40 mg·kg-1·day-1) to block Wnt signaling for 4 weeks. ET-1 contractions were measured by changes of afferent arteriolar diameter. Arteriolar H2O2, O2 -, protein expression and enzymatic activity were assessed using sensitive fluorescence probes, immunoblotting and colorimetric assay separately. RESULTS: Compared to control, diabetic mouse afferent arteriole had increased O2- (+ 84%) and H2O2 (+ 91%) and enhanced responses to ET-1 at 10-8 mol·l-1 (-72±4% of versus -43±4%, P< 0.05) accompanied by reduced protein expressions and activities for catalase and superoxide dismutase 2 (SOD2). Arteriolar O2 - was increased further by ET-1 and contractions to ET-1 reduced by PEG-SOD in both groups whereas H2O2 unchanged by ET-1 and contractions were reduced by PEG-catalase selectively in diabetic mice. The Wnt signaling protein ß-catenin was upregulated (3.3-fold decrease in p-ß-catenin/ß-catenin) while the glycogen synthase kinase-3ß (GSK-3ß) was downregulated (2.6-fold increase in p-GSK-3ß/ GSK-3ß) in preglomerular vessels of diabetic mice. Sulindac normalized the Wnt signaling proteins, arteriolar O2 -, H2O2 and ET-1 contractions while doubling microvascular catalase and SOD2 expression in diabetic mice. CONCLUSION: Increased ROS, notably H2O2 contributes to enhanced afferent arteriolar responses to ET-1 in diabetes, which is closely associated with Wnt signaling. Antioxidant pharmacological strategies targeting Wnt signaling may improve vascular function in diabetic nephropathy.

Nocturnal blood pressure fluctuations measured by using pulse transit time in patients with severe obstructive sleep apnea syndrome.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is related to arterial hypertension. In the present study, we test the hypothesis that patients with severe OSAS have excessive apnea induced blood pressure (BP). METHODS: We investigated 97 patients with an apnea/hypopnea index (AHI) greater than 30. Systolic BP (SBP) was continuously determined by using the pulse transit time (PTT). Apnea/hypopnea induced nocturnal BP fluctuations (NBPFs) were detected and showed phenomena of continuous increases of the SBP baseline. Such periods of SBP baseline elevations ≥ 10 mmHg were called superposition. Respiratory and cardiac parameters were obtained from the polysomnographic investigation. RESULTS: Eighty-four periods of superposition were detected in 48 patients. They occurred mainly during REM sleep (76%). Apnea duration was increased and the time in respiration was reduced in periods of superposition compared to non-superposition periods. In superposition periods mean oxygen saturation (SpO2) and the minimal SpO2 were lower, desaturations were more pronounced, and the mean heart rate (HR) was increased. The maximum SBP during superposition was significantly increased (204 ± 32 vs.171 ± 28 mmHg). The clinic BP was higher in patients with superposition (SBP 149.2 ± 17.5 vs. 140 ± 19.1, DBP 91.5 ± 11.5 vs. 86.3 ± 11.8). CONCLUSIONS: The study reveals that patients with severe OSAS can have periods of BP superposition during night with extremely high SBP and very low oxygen saturation, which may add to a high risk for cardiovascular events during the night.

Neuregulin-1 attenuates development of nephropathy in a type 1 diabetes mouse model with high cardiovascular risk.

Neuregulin-1 (NRG-1) is an endothelium-derived growth factor with cardioprotective and antiatherosclerotic properties and is currently being tested in clinical trials as a treatment for systolic heart failure. In clinical practice, heart failure often coexists with renal failure, sharing an overlapping pathophysiological background. In this study, we hypothesized that NRG-1 might protect against cardiomyopathy, atherosclerosis, and nephropathy within one disease process. We tested this hypothesis in a hypercholesterolemic apolipoprotein E-deficient (apoE(-/-)) type 1 diabetes mouse model prone to the development of cardiomyopathy, atherosclerosis, and nephropathy and compared the effects of NRG-1 with insulin. Upon onset of hyperglycemia induced by streptozotocin, apoE(-/-)mice were treated with vehicle, insulin, or recombinant human (rh)NRG-1 for 14 wk and were compared with nondiabetic apoE(-/-)littermates. Vehicle-treated diabetic apoE(-/-)mice developed left ventricular (LV) dilatation and dysfunction, dense atherosclerotic plaques, and signs of nephropathy. Nephropathy was characterized by abnormalities including hyperfiltration, albuminuria, increased urinary neutrophil gelatinase-associated lipocalin (NGAL), upregulation of renal fibrotic markers, and glomerulosclerosis. rhNRG-1 treatment induced systemic activation of ErbB2 and ErbB4 receptors in both heart and kidneys and prevented LV dilatation, improved LV contractile function, and reduced atherosclerotic plaque size. rhNRG-1 also significantly reduced albuminuria, NGALuria, glomerular fibrosis, and expression of fibrotic markers. Regarding the renal effects of rhNRG-1, further analysis showed that rhNRG-1 inhibited collagen synthesis of glomerular mesangial cells in vitro but did not affect AngII-induced vasoconstriction of glomerular arterioles. In conclusion, systemic administration of rhNRG-1 in hypercholesterolemic type 1 diabetic mice simultaneously protects against complications in the heart, arteries and kidneys.

Continuous blood pressure measurement using the pulse transit time: Comparison to intra-arterial measurement.

Continuous blood pressure (BP) measurement allows the investigation of transient changes in BP and thus may give insights into mechanisms of BP control. We validated a continuous, non-invasive BP measurement based on the pulse transit time (PTT), i.e., BP(PTT), by comparing it with the intra-arterial BP (BP(i.a.)) measurement. Twelve subjects (five females and seven males) were included. BP(i.a.) was obtained from the radial artery using a system from ReCor Medical. Systolic and diastolic BP were calculated using the PTT (BP(PTT), SOMNOscreen). (PTT) was determined from the electrocardiogram and the peripheral pulse wave. The BP was modulated by application of increasing doses of dobutamine (5, 10, 20 µg/kg body mass). Systolic BP(PTT) and systolic BP(i.a.) correlated significantly (R = 0.94). The limits of agreement in the Bland-Altman plot were ± 19 mmHg; the mean values differed by 1 mmHg. The correlation coefficient for the diastolic BP measurements was R = 0.42. The limits of agreement in the Bland-Altman plot were ± 18 mmHg, with a mean difference of 5 mmHg in favour of the BP(PTT). The study demonstrates a significant correlation between the measurement methods for systolic BP. The results encourage the application of PTT-based BP measurement for the evaluation of BP dynamics and pathological BP changes.

Iodinated contrast media cause direct tubular cell damage, leading to oxidative stress, low nitric oxide, and impairment of tubuloglomerular feedback.

Iodinated contrast media (CM) have adverse effects that may result in contrast-induced acute kidney injury. Oxidative stress is believed to play a role in CM-induced kidney injury. We test the hypothesis that oxidative stress and reduced nitric oxide in tubules are consequences of CM-induced direct cell damage and that increased local oxidative stress may increase tubuloglomerular feedback. Rat thick ascending limbs (TAL) were isolated and perfused. Superoxide and nitric oxide were quantified using fluorescence techniques. Cell death rate was estimated using propidium iodide and trypan blue. The function of macula densa and tubuloglomerular feedback responsiveness were measured in isolated, perfused juxtaglomerular apparatuses (JGA) of rabbits. The expression of genes related to oxidative stress and the activity of superoxide dismutase (SOD) were investigated in the renal medulla of rats that received CM. CM increased superoxide concentration and reduced nitric oxide bioavailability in TAL. Propidium iodide fluorescence and trypan blue uptake increased more in CM-perfused TAL than in controls, indicating increased rate of cell death. There were no marked acute changes in the expression of genes related to oxidative stress in medullary segments of Henle's loop. SOD activity did not differ between CM and control groups. The tubuloglomerular feedback in isolated JGA was increased by CM. Tubular cell damage and accompanying oxidative stress in our model are consequences of CM-induced direct cell damage, which also modifies the tubulovascular interaction at the macula densa, and may therefore contribute to disturbances of renal perfusion and filtration.

Role of nitric oxide synthase isoforms for ophthalmic artery reactivity in mice.

Nitric oxide synthases (NOS) are involved in regulation of ocular vascular tone and blood flow. While endothelial NOS (eNOS) has recently been shown to mediate endothelium-dependent vasodilation in mouse retinal arterioles, the contribution of individual NOS isoforms to vascular responses is unknown in the retrobulbar vasculature. Moreover, it is unknown whether the lack of a single NOS isoform affects neuron survival in the retina. Thus, the goal of the present study was to examine the hypothesis that the lack of individual nitric oxide synthase (NOS) isoforms affects the reactivity of mouse ophthalmic arteries and neuron density in the retinal ganglion cell (RGC) layer. Mice deficient in one of the three NOS isoforms (nNOS-/-, iNOS-/- and eNOS-/-) were compared to respective wild type controls. Intraocular pressure (IOP) was measured in conscious mice using rebound tonometry. To examine the role of each NOS isoform for mediating vascular responses, ophthalmic arteries were studied in vitro using video microscopy. Neuron density in the RGC layer was calculated from retinal wholemounts stained with cresyl blue. IOP was similar in all NOS-deficient genotypes and respective wild type controls. In ophthalmic arteries, phenylephrine, nitroprusside and acetylcholine evoked concentration-dependent responses that did not differ between individual NOS-deficient genotypes and their respective controls. In all genotypes except eNOS-/- mice, vasodilation to acetylcholine was markedly reduced after incubation with L-NAME, a non-isoform-selective inhibitor of NOS. In contrast, pharmacological inhibition of nNOS and iNOS had no effect on acetylcholine-induced vasodilation in any of the mouse genotypes. Neuron density in the RGC layer was similar in all NOS-deficient genotypes and respective controls. Our findings suggest that eNOS contributes to endothelium-dependent dilation of murine ophthalmic arteries. However, the chronic lack of eNOS is functionally compensated by NOS-independent vasodilator mechanisms. The lack of a single NOS isoform does not appear to affect IOP or neuron density in the RGC layer.

Novel hemoglobin particles--promising new-generation hemoglobin-based oxygen carriers.

During the last 30 years, artificial oxygen carriers have been investigated intensively with the aim to develop universal blood substitutes. Favorably, hemoglobin-based oxygen carriers (HBOCs) are expected to meet the sophisticated requirements. However, the HBOCs tested until now show serious side effects, which resulted in failure of clinical trials and Food and Drug Administration disapproval. The main problem consists in vasoconstriction triggered by nitric oxide (NO) scavenging or/and oxygen oversupply in the pre-capillary arterioles. HBOCs with a size between 100 nm and 1 µm and high oxygen affinity are needed. Here we present a highly effective and simple fabrication procedure, which can provide hemoglobin particles (HbPs) with a narrow size distribution of around 700 nm, nearly uniform morphology, high oxygen affinity, and low immunogenicity. Isolated mouse glomeruli are successfully perfused with concentrated HbP suspensions without any observable vasoconstriction of the afferent arterioles. The results suggest no oxygen oversupply and limited NO scavenging by these particles, featuring them as a highly promising blood substitute.