A constrained constructive optimization model of branching arteriolar networks in rat skeletal muscle.

Blood flow regulation within the microvasculature reflects a complex interaction of regulatory mechanisms and varies spatially and temporally according to conditions such as metabolism, growth, injury, and disease. Understanding the role of microvascular flow distributions across conditions is of interest to investigators spanning multiple disciplines; however, data collection within networks can be labor-intensive and challenging due to limited resolution. To overcome these experimental challenges, computational network models that can accurately simulate vascular behavior are highly beneficial. Constrained constructive optimization (CCO) is a commonly used algorithm for vascular simulation, particularly well known for its adaptability toward vascular modeling across tissues. The present work demonstrates an implementation of CCO aimed to simulate a branching arteriolar microvasculature in healthy skeletal muscle, validated against literature including comprehensive rat gluteus maximus vasculature datasets, and reviews a list of user-specified adjustable model parameters to understand how their variability affects the simulated networks. Network geometric properties, including mean element diameters, lengths, and numbers of bifurcations per order, Horton's law ratios, and fractal dimension, demonstrate good validation once model parameters are adjusted to experimental data. This model successfully demonstrates hemodynamic properties such as Murray's law and the network Fahraeus effect. Application of centrifugal and Strahler ordering schemes results in divergent descriptions of identical simulated networks. This work introduces a novel CCO-based model focused on generating branching skeletal muscle microvascular arteriolar networks based on adjustable model parameters, thus making it a valuable tool for investigations into skeletal muscle microvascular structure and tissue perfusion.NEW & NOTEWORTHY The present work introduces a CCO-based algorithm for generating branching arteriolar networks, with adjustable model parameters to enable modeling in varying skeletal muscle tissues. The geometric and hemodynamic parameters of the generated networks have been comprehensively validated using experimental data collected previously in-house and from literature. This is one of few validated CCO-based models to specialize in skeletal muscle microvasculature and acts as a beneficial tool for investigating the microvasculature for hypothesis testing and validation.

Complementary and Inducible creERT2 Mouse Models for Functional Evaluation of Endothelial Cell Subtypes in the Bone Marrow.

In the adult bone marrow (BM), endothelial cells (ECs) are an integral component of the hematopoietic stem cell (HSC)-supportive niche, which modulates HSC activity by producing secreted and membrane-bound paracrine signals. Within the BM, distinct vascular arteriole, transitional, and sinusoidal EC subtypes display unique paracrine expression profiles and create anatomically-discrete microenvironments. However, the relative contributions of vascular endothelial subtypes in supporting hematopoiesis is unclear. Moreover, constitutive expression and off-target activity of currently available endothelial-specific and endothelial-subtype-specific murine cre lines potentially confound data analysis and interpretation. To address this, we describe two tamoxifen-inducible cre-expressing lines, Vegfr3-creERT2 and Cx40-creERT2, that efficiently label sinusoidal/transitional and arteriole endothelium respectively in adult marrow, without off-target activity in hematopoietic or perivascular cells. Utilizing an established mouse model in which cre-dependent recombination constitutively-activates MAPK signaling within adult endothelium, we identify arteriole ECs as the driver of MAPK-mediated hematopoietic dysfunction. These results define complementary tamoxifen-inducible creERT2-expressing mouse lines that label functionally-discrete and non-overlapping sinusoidal/transitional and arteriole EC populations in the adult BM, providing a robust toolset to investigate the differential contributions of vascular subtypes in maintaining hematopoietic homeostasis.

A Novel Method for the Measurement of Retinal Arteriolar Bifurcation.

INTRODUCTION: The purpose of this research was to develop protocols for evaluating the bifurcation parameters of retinal arteriole and establish a reference range of normal values. METHODS: In this retrospective study, we measured a total of 1314 retinal arteriolar bifurcations from 100 fundus photographs. We selected 200 from these bifurcations for testing inter-measurer and inter-method agreement. Additionally, we calculated the normal reference range for retinal arteriolar bifurcation parameters and analyzed the effects of gender, age, and anatomical features on retinal arteriolar bifurcation. RESULTS: The measurement method proposed in this study has demonstrated nearly perfect consistency among different measurers, with interclass correlation coefficient (ICC) for all bifurcation parameters of retinal arteriole exceeding 0.95. Among healthy individuals, the retinal arteriolar caliber was narrowest in young adults and increased in children, teenagers, and the elderly; retinal arteriolar caliber was greater in females than in males; and the diameter of the inferior temporal branch exceeded that of the superior temporal branch. The angle between the two branches of retinal arteriolar bifurcation was also greater in females than in males. When using the center of the optic disc as a reference point, the angle between the two branches of the retinal arteriole at the proximal or distal ends increased. In contrast, the estimated optimum theoretical values of retinal arteriolar bifurcation were not affected by these factors. CONCLUSIONS: The method for the measurement of retinal arteriolar bifurcation in this study was highly accurate and reproducible. The diameter and branching angle of the retinal arteriolar bifurcation were more susceptible to the influence of gender, age, and anatomical features. In comparison, the estimated optimum theoretical values of retinal arteriolar bifurcation were relatively stable. Video available for this article.

Early spiral arteriole remodeling in the uterine-placental interface: A rat model.

The mammalian placenta's interface with the parent is a richly vascularized tissue whose development relies upon communication between many different cell types within the uterine microenvironment. The uterine blood vessels of the interface are reshaped during pregnancy into wide-bore, flaccid vessels that convey parental blood to the exchange region of the placenta. Invasive trophoblast as well as parental uterine macrophages and Natural Killer cells are involved in the stepwise remodeling of these vessels and their respective contributions to this crucial process are still being delineated. However, the earliest steps in arteriole remodeling are understudied as they are difficult to study in humans, and other species lack the deep trophoblast invasion that is so prominent a feature of placentation in humans. Here, we further characterize the rat, with deep hemochorial placentation akin to humans, as a model system in which to tease apart the earliest, relatively understudied events in spiral arteriole remodeling. We show that the rat uterine-placental interface increases in size and vascularity rapidly, before trophoblast invasion. The remodeling stages in the arterioles of the rat uterine-placental interface follow a sequence of anatomical changes similar to those in humans, and there are changes to the arterioles' muscular tunica media prior to the marked influx of immune cells. The rat is a tractable model in which to better understand the cell/cell interactions occurring in vivo in an intact tissue microenvironment over time.

Commonly used anesthetics modify alcohol and (-)-trans-delta9-tetrahydrocannabinol in vivo effects on rat cerebral arterioles.

BACKGROUND: Ethyl alcohol and cannabis are widely used recreational substances with distinct effects on the brain. These drugs increase accidental injuries requiring treatment under anesthesia. Moreover, alcohol and cannabis are often used in anesthetized rodents for biomedical research. Here, we compared the influence of commonly used forms of anesthesia, injectable ketamine/xylazine (KX) versus inhalant isoflurane, on alcohol- and (-)-trans-delta9-tetrahydrocannabinol (THC) effects on cerebral arteriole diameter evaluated in vivo. METHODS: Studies were performed on male and female Sprague-Dawley rats subjected to intracarotid catheter placement for drug infusion, and cranial window surgery for monitoring pial arteriole diameter. Depth of anesthesia was monitored every 10-15 min by toe-pinch. Under KX, the number of toe-pinch responders was maximal after the first dose of anesthesia and diminished over time in both males and females. In contrast, the number of toe-pinch responders under isoflurane slowly raised over time, leading to increase in isoflurane percentage until deep anesthesia was re-established. Rectal temperature under KX remained stable in males while dropping in females. As expected for gaseous anesthesia, both males and females exhibited rectal temperature drops under isoflurane. RESULTS: Infusion of 50 mM alcohol (ethanol, EtOH) into the cerebral circulation rendered robust constriction in males under KX anesthesia, this alcohol action being significantly smaller, but still present under isoflurane anesthesia. In females, EtOH did not cause measurable changes in pial arteriole diameter regardless of the anesthetic. These findings indicate a strong sex bias with regards to EtOH induced vasoconstriction. Infusion of 42 nM THC in males and females under isoflurane tended to constrict cerebral arterioles in both males and females when compared to isovolumic infusion of THC vehicle (dimethyl sulfoxide in saline). Moreover, THC-driven changes in arteriole diameter significantly differed in magnitude depending on the anesthetic used. Simultaneous administration of 50 mM alcohol and 42 nM THC to males constricted cerebral arterioles regardless of the anesthetic used. In females, constriction by the combined drugs was also observed, with limited influence by anesthetic presence. CONCLUSIONS: We demonstrate that two commonly used anesthetic formulations differentially influence the level of vasoconstriction caused by alcohol and THC actions in cerebral arterioles.

[Quercetin improves pulmonary arterial hypertension in rats by regulating the HMGB1/RAGE/NF-κB pathway].

OBJECTIVE: To explore the mechanism through which quercetin improves pulmonary arterial hypertension (PAH). METHODS: Rat models of hypoxic pulmonary hypertension were established by exposure to hypoxia for 8-10 h each day (6 days a week for 4 weeks), and before each hypoxic exposure, the rats were given intragastric administration of 100 mg/kg quercetin or saline. After the treatments, the right ventricular systolic pressure (RVSP) and pulmonary artery systolic pressure of the rats were recorded. The right ventricular hypertrophy index (RVHI) was measured to evaluate right ventricular hypertrophy. HE staining was used to observe the remodeling of the pulmonary arterioles. The right cardiac function of the rats was evaluated by ultrasound. The protein levels of HMGB1, RAGE, NF-κB, Bax, Bcl-2 and cleaved caspase-3 in the lung tissue of the rats were detected using Western blotting. RESULTS: Compared with the rats maintained in normoxia, the rats with chronic hypoxic exposure showed significantly increased RVHI and RVSP (P<0.01), which were obviously lowered by quercetin treatment (P<0.01). HE staining showed significant pulmonary artery wall thickening with reduced lumen diameter in hypoxia group, and quercetin treatment effectively improved pulmonary vascular remodeling. Ultrasound examination revealed a significantly increased RVFW and a lowered PAT/PET ratio in hypoxia group (P<0.01), and such changes were ameliorated by quercetin treatment (P<0.01). Chronic hypoxia significantly increased the protein expressions of HMGB1 (P<0.01), RAGE, NF-κB and Bcl-2 (P<0.01) and lowered the protein expressions of Bax and cleaved caspase-3 (P<0.01); Quercetin treatment obviously lowered the protein expressions of HMGB1, NF-κB (P<0.05), RAGE (P<0.01) and (P<0.05) and increased the expressions of Bax and cleaved caspase-3 in the rat models (P<0.01). CONCLUSION: Quercetin improves pulmonary hypertension in rats possibly by promoting apoptosis through the HMGB1/RAGE/NF-κB pathway.

Interaction of Angiotensin II AT1 Receptors with Purinergic P2X Receptors in Regulating Renal Afferent Arterioles in Angiotensin II-Dependent Hypertension.

In angiotensin II (Ang II)-dependent hypertension, Ang II activates angiotensin II type 1 receptors (AT1R) on renal vascular smooth muscle cells, leading to renal vasoconstriction with eventual glomerular and tubular injury and interstitial inflammation. While afferent arteriolar vasoconstriction is initiated by the increased intrarenal levels of Ang II activating AT1R, the progressive increases in arterial pressure stimulate the paracrine secretion of adenosine triphosphate (ATP), leading to the purinergic P2X receptor (P2XR)-mediated constriction of afferent arterioles. Thus, the afferent arteriolar tone is maintained by two powerful systems eliciting the co-existing activation of P2XR and AT1R. This raises the conundrum of how the AT1R and P2XR can both be responsible for most of the increased renal afferent vascular resistance existing in angiotensin-dependent hypertension. Its resolution implies that AT1R and P2XR share common receptor or post receptor signaling mechanisms which converge to maintain renal vasoconstriction in Ang II-dependent hypertension. In this review, we briefly discuss (1) the regulation of renal afferent arterioles in Ang II-dependent hypertension, (2) the interaction of AT1R and P2XR activation in regulating renal afferent arterioles in a setting of hypertension, (3) mechanisms regulating ATP release and effect of angiotensin II on ATP release, and (4) the possible intracellular pathways involved in AT1R and P2XR interactions. Emerging evidence supports the hypothesis that P2X1R, P2X7R, and AT1R actions converge at receptor or post-receptor signaling pathways but that P2XR exerts a dominant influence abrogating the actions of AT1R on renal afferent arterioles in Ang II-dependent hypertension. This finding raises clinical implications for the design of therapeutic interventions that will prevent the impairment of kidney function and subsequent tissue injury.

The counterbalance of endothelial glycocalyx and high wall shear stress to low-density lipoprotein concentration polarization in mouse ear skin arterioles.

BACKGROUND AND AIMS: Atherosclerosis preferentially occurs at regions in arterial branching, curvature, and stenosis, which may be explained by the geometric predilection of low-density lipoprotein (LDL) concentration polarization that has been investigated in major arteries in previous studies. Whether this also happens in arterioles remains unknown. METHODS: Herein, a radially non-uniform distribution of LDL particles and a heterogeneous endothelial glycocalyx layer in the mouse ear arterioles, as shown by fluorescein isothiocyanate labeled wheat germ agglutinin (WGA-FITC), were successfully observed by a non-invasive two-photon laser-scanning microscopy (TPLSM) technique. The stagnant film theory was applied as the fitting function to evaluate LDL concentration polarization in arterioles. RESULTS: The concentration polarization rate (CPR, the ratio of the number of polarized cases to that of total cases) in the inner walls of curved and branched arterioles was 22% and 31% higher than the outer counterparts, respectively. Results from the binary logistic regression and multiple linear regression analysis showed that endothelial glycocalyx thickness increases CPR and the thickness of the concentration polarization layer (CPL). Flow field computation indicates no obvious disturbances or vortex in modeled arterioles with different geometries and the mean wall shear stress is about 7.7-9.0 Pa. CONCLUSIONS: These findings suggest a geometric predilection of LDL concentration polarization in arterioles for the first time, and the existence of an endothelial glycocalyx, acting together with a relatively high wall shear stress in arterioles, may explain to some extent why atherosclerosis rarely occurs in these regions.

Transport of nitrite from large arteries modulates regional blood flow during stress and exercise.

Background: Acute cardiovascular stress increases systemic wall shear stress (WSS)-a frictional force exerted by the flow of blood on vessel walls-which raises plasma nitrite concentration due to enhanced endothelial nitric oxide synthase (eNOS) activity. Upstream eNOS inhibition modulates distal perfusion, and autonomic stress increases both the consumption and vasodilatory effects of endogenous nitrite. Plasma nitrite maintains vascular homeostasis during exercise and disruption of nitrite bioavailability can lead to intermittent claudication. Hypothesis: During acute cardiovascular stress or strenuous exercise, we hypothesize enhanced production of nitric oxide (NO) by vascular endothelial cells raises nitrite concentrations in near-wall layers of flowing blood, resulting in cumulative NO concentrations in downstream arterioles sufficient for vasodilation. Confirmation and implications: Utilizing a multiscale model of nitrite transport in bifurcating arteries, we tested the hypothesis for femoral artery flow under resting and exercised states of cardiovascular stress. Results indicate intravascular transport of nitrite from upstream endothelium could result in vasodilator-active levels of nitrite in downstream resistance vessels. The hypothesis could be confirmed utilizing artery-on-a-chip technology to measure NO production rates directly and help validate numerical model predictions. Further characterization of this mechanism may improve our understanding of symptomatic peripheral artery occlusive disease and exercise physiology.

Perivascular Macrophages Mediate Microvasospasms After Experimental Subarachnoid Hemorrhage.

BACKGROUND: Subarachnoid hemorrhage (SAH) is characterized by acute and delayed reductions of cerebral blood flow (CBF) caused, among others, by spasms of cerebral arteries and arterioles. Recently, the inactivation of perivascular macrophages (PVM) has been demonstrated to improve neurological outcomes after experimental SAH, but the underlying mechanisms of protection remain unclear. The aim of our exploratory study was, therefore, to investigate the role of PVM in the formation of acute microvasospasms after experimental SAH. METHODS: PVMs were depleted in 8- to 10-week-old male C57BL/6 mice (n=8/group) by intracerebroventricular application of clodronate-loaded liposomes and compared with mice with vehicle liposome injections. Seven days later, SAH was induced by filament perforation under continuous monitoring of CBF and intracranial pressure. Results were compared with sham-operated animals and animals who underwent SAH induction but no liposome injection (n=4/group each). Six hours after SAH induction or sham surgery, numbers of microvasospasms per volume of interest and % of affected pial and penetrating arterioles were examined in 9 standardized regions of interest per animal by in vivo 2-photon microscopy. Depletion of PVMs was proven by quantification of PVMs/mm3 identified by immunohistochemical staining for CD206 and Collagen IV. Statistical significance was tested with t tests for parametric data and Mann-Whitney U test for nonparametric data. RESULTS: PVMs were located around pial and intraparenchymal arterioles and were effectively depleted by clodronate from 671±28 to 46±14 PVMs/mm3 (P<0.001). After SAH, microvasospasms was observed in pial arteries and penetrating and precapillary arterioles and were accompanied by an increase to 1405±142 PVMs/mm3. PVM depletion significantly reduced the number of microvasospasms from 9 IQR 5 to 3 IQR 3 (P<0.001). CONCLUSIONS: Our results suggest that PVMs contribute to the formation of microvasospasms after experimental SAH.

Manufacturing the multiscale vascular hierarchy: progress toward solving the grand challenge of tissue engineering.

In human vascular anatomy, blood flows from the heart to organs and tissues through a hierarchical vascular tree, comprising large arteries that branch into arterioles and further into capillaries, where gas and nutrient exchange occur. Engineering a complete, integrated vascular hierarchy with vessels large enough to suture, strong enough to withstand hemodynamic forces, and a branching structure to permit immediate perfusion of a fluidic circuit across scales would be transformative for regenerative medicine (RM), enabling the translation of engineered tissues of clinically relevant size, and perhaps whole organs. How close are we to solving this biological plumbing problem? In this review, we highlight advances in engineered vasculature at individual scales and focus on recent strategies to integrate across scales.

A novel functional role for the classic CNS neurotransmitters, GABA, glycine, and glutamate, in the kidney: potent and opposing regulators of the renal vasculature.

The presence of a renal GABA/glutamate system has previously been described; however, its functional significance in the kidney remains undefined. We hypothesized, given its extensive presence in the kidney, that activation of this GABA/glutamate system would elicit a vasoactive response from the renal microvessels. The functional data here demonstrate, for the first time, that activation of endogenous GABA and glutamate receptors in the kidney significantly alters microvessel diameter with important implications for influencing renal blood flow. Renal blood flow is regulated in both the renal cortical and medullary microcirculatory beds via diverse signaling pathways. GABA- and glutamate-mediated effects on renal capillaries are strikingly similar to those central to the regulation of central nervous system capillaries, that is, exposing renal tissue to physiological concentrations of GABA, glutamate, and glycine led to alterations in the way that contractile cells, pericytes, and smooth muscle cells, regulate microvessel diameter in the kidney. Since dysregulated renal blood flow is linked to chronic renal disease, alterations in the renal GABA/glutamate system, possibly through prescription drugs, could significantly impact long-term kidney function.NEW & NOTEWORTHY Functional data here offer novel insight into the vasoactive activity of the renal GABA/glutamate system. These data show that activation of endogenous GABA and glutamate receptors in the kidney significantly alters microvessel diameter. Furthermore, the results show that these antiepileptic drugs are as potentially challenging to the kidney as nonsteroidal anti-inflammatory drugs.

Retinal vessel dynamics analysis as a surrogate marker for raised intracranial pressure in patients with suspected idiopathic intracranial hypertension.

INTRODUCTION: Retinal vessel dynamics analysis has proven to be a viable, non-invasive surrogate marker for increased intracranial pressure. We aimed to test this method in patients with suspected idiopathic intracranial hypertension. METHODS: Patients with suspected idiopathic intracranial hypertension were prospectively enrolled for hand-held fundus-videography during diagnostic lumbar puncture. After extracting optic disc images, peripapillary arteriole-to-venule-ratios were measured using machine-learning algorithms with manual identification control. A general linear model was applied to arteriole-to-venule-ratios and corresponding lumbar opening pressures to estimate cerebrospinal fluid pressure. RESULTS: Twenty-five patients were included with a significant difference in arteriole-to-venule-ratio between patients with (n = 17) and without (n = 8) idiopathic intracranial hypertension (0.78 ± 0.10 vs 0.90 ± 0.08, p = 0.006). Arteriole-to-venule-ratio correlated inversely with lumbar opening pressure (slope regression estimate -0.0043 (95% CI -0.0073 to -0.0023), p = 0.002) and the association was stronger when lumbar opening pressure exceeded 15 mm Hg (20 cm H2O) (slope regression estimate -0.0080 (95% CI -0.0123 to -0.0039), p < 0.001). Estimated cerebrospinal fluid pressure predicted increased lumbar opening pressure >20 mm Hg (27 cm H2O) with 78% sensitivity and 92% specificity (AUC 0.81, p = 0.02). A stand-alone arteriole-to-venule-ratio measurement predicting lumbar opening pressure >20 mm Hg (27 cm H2O) was inferior with a 48% sensitivity and 92% specificity (AUC 0.73, p = 0.002). CONCLUSION: Retinal vessel dynamics analysis with the described model for estimating cerebrospinal fluid pressure is a promising non-invasive method with a high sensitivity and specificity for detecting elevated intracranial pressure at follow-up assessments of patients with confirmed idiopathic intracranial hypertension if initial lumbar opening pressure and arteriole-to-venule-ratio data are available.

A Novel Computational Biomechanics Framework to Model Vascular Mechanopropagation in Deep Bone Marrow.

The mechanical stimuli generated by body exercise can be transmitted from cortical bone into the deep bone marrow (mechanopropagation). Excitingly, a mechanosensitive perivascular stem cell niche is recently identified within the bone marrow for osteogenesis and lymphopoiesis. Although it is long known that they are maintained by exercise-induced mechanical stimulation, the mechanopropagation from compact bone to deep bone marrow vasculature remains elusive of this fundamental mechanobiology field. No experimental system is available yet to directly understand such exercise-induced mechanopropagation at the bone-vessel interface. To this end, taking advantage of the revolutionary in vivo 3D deep bone imaging, an integrated computational biomechanics framework to quantitatively evaluate the mechanopropagation capabilities for bone marrow arterioles, arteries, and sinusoids is devised. As a highlight, the 3D geometries of blood vessels are smoothly reconstructed in the presence of vessel wall thickness and intravascular pulse pressure. By implementing the 5-parameter Mooney-Rivlin model that simulates the hyperelastic vessel properties, finite element analysis to thoroughly investigate the mechanical effects of exercise-induced intravascular vibratory stretching on bone marrow vasculature is performed. In addition, the blood pressure and cortical bone bending effects on vascular mechanoproperties are examined. For the first time, movement-induced mechanopropagation from the hard cortical bone to the soft vasculature in the bone marrow is numerically simulated. It is concluded that arterioles and arteries are much more efficient in propagating mechanical force than sinusoids due to their stiffness. In the future, this in-silico approach can be combined with other clinical imaging modalities for subject/patient-specific vascular reconstruction and biomechanical analysis, providing large-scale phenotypic data for personalized mechanobiology discovery.

Evaluation of Retinal Vascularity Index in Patients with COVID-19: A Case-Control Study.

INTRODUCTION: The purpose of this study was to evaluate the impact of COVID-19 infection on retinal microvasculature by topographically mapping the retinal arteriole-to-venule ratio (AVR). METHODS: In a comparative cross-sectional case-control study, fundus photos were obtained in COVID-19-infected patients and healthy controls. AVT was measured over 16 points across the retina using retinal vascularity index (RVI)-a novel semi-automated computerized parameter based on retinal vasculature. RESULTS: A total of 51 COVID-19-positive patients and 65 healthy controls were enrolled in the study. Overall, the mean RVI of all 16 points across the retina was 0.34 ± 0.02 in patients with COVID-19 and 0.33 ± 0.02 in control subjects (p = 0.64). Out of the 16 points being measured, three points had a statistically significant greater value in patients with COVID compared to normal controls. CONCLUSION: Localised greater RVI values were found in some of the points in COVID-19-positive patients, which likely indicates a more focal change of the vasculature.

Three-dimensional visualization on the relationship between tubules after macula densa and afferent arterioles in mouse kidney / 解剖学报

Objective To establish the spatial course of distal tubule and afferent arterioles after macula densa, and to locate and detect the proteins in the adjacent parts by using three-dimensional visualization technology of microstructure. Methods C57 BL/6J mice were fixed by perfusion and embedded in epon 812. Tissue blocks were cut perpendicular to the longitudinal axis of the kidney. And a total of 720, 2. 5 μm-thick consecutive sections were obtained from the renal capsule to the outer stripe of the renal outer medulla. After aligning the digital microscopic images through computer registration procedures, the tubules and vessels were traced by 3D reconstruction program edited by C Language. Selecting the tissue sections of the contact site and applying the improved immunoperoxidase staining method to detect H

Automatic quantitative measurement of left atrial pressure using mitral regurgitation spectrum: clinical study on comparison with floating catheter.

INTRODUCTION: To explore how to measure LAPEq accurately and quantitatively, that is, the left atrial pressure (LAP) measured and calculated by equation method using mitral regurgitation spectrum. METHODS: The mitral regurgitation spectrum, pulmonary arteriolar wedge pressure (PAWP) and invasive arterial systolic pressure of radial artery of 28 patients were collected simultaneously, including 3 patients with rheumatic heart disease, 15 patients with mitral valve prolapse and 10 patients with coronary artery bypass grafting, patients with moderate or above aortic stenosis were excluded. LAPBp (Doppler sphygmomanometer method), LAPEq (Equation method) and LAPC (Catheter method) were measured synchronously, and the measurement results of the three methods were compared and analyzed. A special intelligent Doppler spectrum analysis software was self-designed to accurately measure LAPEq. This study had been approved by the ethics committee of the Northern Theater General Hospital (K-2019-17), and applied for clinical trial (No. Chictr 190023812). RESULTS: It was found that there was no significant statistical difference between the measurement results of LAPC and LAPEq (t = 0.954, P = 0.348), and significant correlation between the two methods [r = 0.908(0.844, 0.964), P < 0.001]. Although the measurement results of LAPC and LAPBP are consistent in the condition of non-severe eccentric mitral regurgitation, there are significant differences in the overall case and weak correlation between the two methods [r = 0.210, (-0.101, 0.510), P = 0.090]. In MVP patients with P1 or P3 prolapse, the peak pressure difference of MR was underestimated due to the serious eccentricity of MR, which affected the accuracy of LAPBP measurement. CONCLUSIONS: It was shown that there is a good correlation between LAPEq and LAPC, which verifies that the non-invasive and direct quantitative measurement of left atrial pressure based on mitral regurgitation spectrum is feasible and has a good application prospect.

Downregulation of CYP17A1 by 20-hydroxyecdysone: plasma progesterone and its vasodilatory properties.

Aim: To investigate the effect of 20-hydroxyecdysone on steroidogenic pathway genes and plasma progesterone, and its potential impact on vascular functions. Methods: Chimeric mice with humanized liver were treated with 20-hydroxyecdysone for 3 days, and hepatic steroidogenic pathway genes and plasma progesterone were measured by transcriptomics and GC-MS/MS, respectively. Direct effects on muscle and mesenteric arterioles were assessed by myography. Results: CYP17A1 was downregulated in 20-hydroxyecdysone-treated mice compared with untreated group (p = 0.04), with an insignificant increase in plasma progesterone. Progesterone caused vasorelaxation which was blocked by 60 mM KCl, but unaffected by nitric oxide synthase inhibition. Conclusion: In the short term, 20-hydroxyecdysone mediates CYP17A1 downregulation without a significant increase in plasma progesterone, which has a vasodilatory effect involving inhibition of voltage-dependent calcium channels, and the potential to enhance 20-hydroxyecdysone vasorelaxation.

Assaying activity-dependent arteriole and capillary responses in brain slices.

Significance: Neurovascular coupling (NVC) is the process that increases cerebral blood flow in response to neuronal activity. NVC is orchestrated by signaling between neurons, glia, and vascular cells. Elucidating the mechanisms underlying NVC at different vascular segments and in different brain regions is imperative for understanding of brain function and mechanisms of dysfunction. Aim: Our goal is to describe a protocol for concurrently monitoring stimulation-evoked neuronal activity and resultant vascular responses in acute brain slices. Approach: We describe a step-by-step protocol that allows the study of endogenous NVC mechanisms engaged by neuronal activity in a controlled, reduced preparation. Results: This ex vivo NVC assay allows researchers to disentangle the mechanisms regulating the contractile responses of different vascular segments in response to neuronal firing independent of flow and pressure mediated effects from connected vessels. It also enables easy pharmacological manipulations in a simplified, reduced system and can be combined with Ca 2 + imaging or broader electrophysiology techniques to obtain multimodal data during NVC. Conclusions: The ex vivo NVC assay will facilitate investigations of cellular and molecular mechanisms that give rise to NVC and should serve as a valuable complement to in vivo imaging methods.