A morphometric analysis of the retinal arterioles with adaptive optics imaging in RPE65-associated retinal dystrophy after treatment with voretigene neparvovec

PURPOSE

To investigate the changes in retinal arterial architecture after treatment with voretigene neparvovec in patients with retinal dystrophy caused by bi-allelic mutations in the RPE65 gene.

METHODS

Sixteen eyes treated with voretigene neparvovec at the University Eye Clinic in Tuebingen, Germany, underwent adaptive optics ophthalmoscopy (AO) imaging at baseline and 2 weeks, 1, 3, 6 and 12 months after treatment. Follow-up was performed in six eyes of four patients. For each eye, five different positions at arterial vessels were selected and the wall-to-lumen ratio (WLR), the lumen diameter (LD) and the wall cross-sectional area (WCSA) were measured by the manufacturer's software over the observational period.

RESULTS

Vast retinal atrophy dominated all gained AO images. WLR fluctuated in the observation period without statistically significant change. LD and WCSA changed significantly after 2 weeks from the baseline examination and returned to values similar to baseline thereafter. There were no signs of inflammation such as macrophages or perivascular accumulated fluid visible.

CONCLUSION

AO imaging of the retinal vessels in RPE65-associated retinal dystrophies (IRD) is challenging. There was no change in the retinal arterial vasculature over the observation period of 12 months that would indicate inflammatory changes. Decrease of the LD and WCSA shortly after treatment might be caused by the perioperative prednisolone intake. AO of retinal vessels can be used as a diagnostic module to complement monitoring the disease and effects of genetic treatments if the acquisition is possible in selected cases.

The vascular geometry of the choriocapillaris is associated with spatially heterogeneous molecular exchange with the outer retina

Vision relies on the continuous exchange of material between the photoreceptors, retinal pigment epithelium and choriocapillaris, a dense microvascular bed located underneath the outer retina. The anatomy and physiology of the choriocapillaris and their association with retinal homeostasis have proven difficult to characterize, mainly because of the unusual geometry of this vascular bed. By analysing tissue dissected from 81 human eyes, we show that the thickness of the choriocapillaris does not vary significantly over large portions of the macula or with age. Assessments of spatial variations in the anatomy of the choriocapillaris in three additional human eyes indicate that the location of arteriolar and venular vessels connected to the plane of the choriocapillaris is non-random, and that venular insertions cluster around arteriolar ones. Mathematical models built upon these anatomical analyses reveal that the choriocapillaris contains regions where the transport of passive elements is dominated by diffusion, and that these diffusion-limited regions represent areas of reduced exchange with the outer retina. The width of diffusion-limited regions is determined by arterial flow rate and the relative arrangement of arteriolar and venular insertions. These analyses demonstrate that the apparent complexity of the choriocapillaris conceals a fine balance between several anatomical and functional parameters to effectively support homeostasis of the outer retina. KEY POINTS: The choriocapillaris is the capillary bed supporting the metabolism of photoreceptors and retinal pigment epithelium, two critical components of the visual system located in the outer part of the retina. The choriocapillaris has evolved a planar multipolar vascular geometry that differs markedly from the branched topology of most vasculatures in the human body. Here, we report that this planar multipolar vascular geometry is associated with spatially heterogenous molecular exchange between choriocapillaris and outer retina. Our data and analyses highlight a necessary balance between choriocapillaris anatomical and functional parameters to effectively support homeostasis of the outer retina.

Ca2+ oscillation in vascular smooth muscle cells control myogenic spontaneous vasomotion and counteract post-ischemic no-reflow

Ischemic stroke produces the highest adult disability. Despite successful recanalization, no-reflow, or the futile restoration of the cerebral perfusion after ischemia, is a major cause of brain lesion expansion. However, the vascular mechanism underlying this hypoperfusion is largely unknown, and no approach is available to actively promote optimal reperfusion to treat no-reflow. Here, by combining two-photon laser scanning microscopy (2PLSM) and a mouse middle cerebral arteriolar occlusion (MCAO) model, we find myogenic vasomotion deficits correlated with post-ischemic cerebral circulation interruptions and no-reflow. Transient occlusion-induced transient loss of mitochondrial membrane potential (ΔΨm) permanently impairs mitochondria-endoplasmic reticulum (ER) contacts and abolish Ca2+ oscillation in smooth muscle cells (SMCs), the driving force of myogenic spontaneous vasomotion. Furthermore, tethering mitochondria and ER by specific overexpression of ME-Linker in SMCs restores cytosolic Ca2+ homeostasis, remotivates myogenic spontaneous vasomotion, achieves optimal reperfusion, and ameliorates neurological injury. Collectively, the maintaining of arteriolar myogenic vasomotion and mitochondria-ER contacts in SMCs, are of critical importance in preventing post-ischemic no-reflow.

Early vascular damage in retinal microcirculation in arterial hypertension: the Czech post-MONICA study

Retinal microcirculation reflects retinal perfusion abnormalities and retinal arterial structural changes at relatively early stages of various cardiovascular diseases. Wall-to-lumen ratio (WLR) may represent the earliest step in hypertension-mediated organ damage.Our objective was to compare functional and structural parameters of retinal microcirculation in a randomly selected urban population sample, in hypertensive and normotensive individuals.

DESIGN AND METHOD

A total of 398 randomly selected individuals from an urban population aged 25-65 years, residing in Pilsen, Czech Republic, were screened for major cardiovascular risk factors. Retinal microcirculation was assessed using scanning laser Doppler flowmetry, with data evaluable in 343 patients. Complete data were available for 342 individuals divided into four groups based on blood pressure and control status of hypertension: normotensive individuals ( n  = 213), treated controlled hypertensive individuals ( n  = 30), treated uncontrolled hypertensive individuals ( n  = 26), and newly detected/untreated hypertensive individuals ( n  = 73).

RESULTS

There was a tendency to higher wall thickness in treated but uncontrolled hypertensive patients (compared to normotensive and treated controlled hypertensive individuals). WLR was significantly increased in treated but uncontrolled hypertensive patients as well as in individuals with newly detected thus untreated hypertension or in patients with known but untreated hypertension. There was no difference in WLR in treated, controlled hypertensive patients compared with normotensive individuals.

CONCLUSION

Our results show that an increased WLR, reflecting early vascular damage, was found in newly detected individuals with hypertension and in untreated hypertensive patients, reflecting early hypertension-mediated vascular damage. Early initiation of hypertension treatment may be warranted.

Funny coronary arteriole perforation causes tamponade post-primary percutaneous coronary intervention

An emergency transradial coronary angiography in a 68-year-old woman demonstrated sub-total occlusion of the proximal left anterior descending artery.

Small arteriole sign: an imaging feature for staging T4a colon cancer

OBJECTIVES

By analyzing the distribution of existing and newly proposed staging imaging features in pT1-3 and pT4a tumors, we searched for a salient feature and validated its diagnostic performance.

METHODS

Preoperative multiphase contrast-enhanced CT images of the training cohort were retrospectively collected at three centers from January 2016 to December 2017. We used the chi-square test to analyze the distribution of several stage-related imaging features in pT1-3 and pT4a tumors, including small arteriole sign (SAS), outer edge of the intestine, tumor invasion range, and peritumoral adipose tissue. Preoperative multiphase contrast-enhanced CT images of the validation cohort were retrospectively collected at Beijing Cancer Hospital from January 2018 to December 2018. The diagnostic performance of the selected imaging feature, including accuracy, sensitivity, and specificity, was validated and compared with the conventional clinical tumor stage (cT) by the McNemar test.

RESULTS

In the training cohort, a total of 268 patients were enrolled, and only SAS was significantly different between pT1-3 and pT4a tumors. The accuracy, sensitivity, and specificity of the SAS and conventional cT in differentiating T1-3 and T4a tumors were 94.4%, 81.6%, and 97.3% and 53.7%, 32.7%, and 58.4%, respectively (all p < 0.001). In the validation cohort, a total of 135 patients were collected. The accuracy, sensitivity, and specificity of the SAS and the conventional cT were 93.3%, 76.2%, and 96.5% and 62.2%, 38.1%, and 66.7%, respectively (p < 0.001, p = 0.021, p < 0.001).

CONCLUSION

Small arteriole sign positivity, an indirect imaging feature of serosa invasion, may improve the accuracy of identifying T4a colon cancer.

CLINICAL RELEVANCE STATEMENT

Small arteriole sign helps to distinguish T1-3 and T4a colon cancer and further improves the accuracy of preoperative CT staging of colon cancer.

KEY POINTS

• The accuracy of preoperative CT staging of colon cancer is not ideal, especially for T4a tumors. • Small arteriole sign (SAS) is a newly defined imaging feature that shows the appearance of tumor-supplying arterioles at the site where they penetrate the intestine wall. • SAS is an indirect imaging marker of tumor invasion into the serosa with a great value in distinguishing between T1-3 and T4a colon cancer.

High doses of hydroxyapatite nanoparticle (nHAP) impairs microcirculation in vivo

Nanoparticles has surrounded the population by their use in electronics, medicine and cosmetics. The exposure to nanoparticles coming from different sources is uncountable as the amount of nanoparticles in which a person is exposed daily. In this direction and considering that microcirculation is the main and most affected system by nanoparticles in the first moment, responsible to transport and deal with nanoparticles internally, we evaluated a massive exposure (1 g/Kg) of a well-known nanoparticle (hydroxyapatite) and the impact on the microvessels. The results showed a massive destruction of venules, arterioles, and capillaries when nHAPs were administered topically. However, systemic administration of high doses of nHAP did not affect microcirculation but altered biochemical parameters of blood samples from treated animals. The data demonstrated that even well documented nanoparticles at high doses might affect the whole-body homeostasis. Finally, the results raise the necessity for further investigation of the effect of nanoparticles in microcirculation and the impact in the whole-body homeostasis.

Food intake in South African children and retinal microvascular health: The ExAMIN Youth SA study

BACKGROUND AND AIMS

Retinal arteriolar narrowing and venular widening are associated with increased cardiovascular risk, even at young ages. Whether diet contributes to early microvascular changes in children is not widely explored. We explored the associations of frequency of healthy and unhealthy food group intake with retinal vessel calibers in black and white children.

METHODS AND RESULTS

This study included school-aged (5-9 years) black (N = 433, 7.46 ± 0.98 years), and white (N = 403, 7.43 ± 0.82 years) children. Anthropometric and blood pressure measurements were taken, along with retinal vessel calibers (central retinal arteriolar (CRAE) and venular (CRVE) equivalents). Frequencies of food group intake were assessed using a food-frequency questionnaire. A factor analysis was performed to describe food group patters. Independent associations between retinal vessel calibers and frequencies of food group intake and food group patters were explored. In black children, cookies, cakes, and biscuits were associated with narrower arterioles (p < 0.05). In white children, cold sweetened beverages were associated with narrower arterioles (p = 0.02), whereas salty snacks were associated with narrower arterioles (p = 0.01) and wider venules (p < 0.05). Fruits were positively associated with CRAE (p = 0.03) in white children only.

CONCLUSION

A higher frequency of unhealthy food group consumption was associated with retinal arteriolar narrowing and venular widening in both black and white children. However, fruit intake was shown beneficial for retinal microvascular health in white children only. Our findings may highlight the importance of promoting healthy eating patterns from early childhood which may reduce the risk of premature cardiovascular disease development.

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.

Colour tone of retinal arterioles imaged with a colour scanning laser ophthalmoscope can be an indicator of systemic arterial stiffness

OBJECTIVE

Colour scanning laser ophthalmoscope (cSLO) offers several advantages, including improved image quality and better visualisation of the retinal structures compared with colour fundus photograph (CFP). This study aimed to identify whether cSLO could be used to predict systemic arterial stiffness.

METHODS AND ANALYSIS

We retrospectively analysed the data of 54 patients with 103 eyes. In addition to blood pressure and blood data, all patients had cardio-ankle vascular index (CAVI) measurements, as well as images of the fundus acquired using cSLO and CFP. We determined the retinal artery sclerosis (RAS) index from the colour of the retinal artery in cSLO images, the ratio of arterial to venous diameter (A/V ratio), and Scheie's classification in CFP images. The correlation between each parameter and CAVI was examined using Spearman's rank correlation coefficient, and the correlation between Scheie's classification and CAVI was examined using Steel-Dowass tests.

RESULTS

CAVI showed a significant positive correlation with the RAS index (r=0.679, p<0.001) but not with the A/V ratio or Scheie's classification. Multiple regression analysis showed that the RAS index was significantly and independently correlated with CAVI.

CONCLUSION

cSLO is a non-invasive imaging modality that has the potential to accurately and instantaneously detect early systemic arterial stiffness.

Estimation of shear stress heterogeneity along capillary segments in angiogenic rat mesenteric microvascular networks

OBJECTIVE

Fluid shear stress is thought to be a regulator of endothelial cell behavior during angiogenesis. The link, however, requires an understanding of stress values at the capillary level in angiogenic microvascular networks. Critical questions remain. What are the stresses? Do capillaries experience similar stress magnitudes? Can variations explain vessel-specific behavior? The objective of this study was to estimate segment-specific shear stresses in angiogenic networks.

METHODS

Images of angiogenic networks characterized by increased vascular density were obtained from rat mesenteric tissues stimulated by compound 48/80-induced mast cell degranulation. Vessels were identified by perfusion of a 40 kDa fixable dextran prior to harvesting and immunolabeling for PECAM. Using a network flow-based segment model with physiologically relevant parameters, stresses were computed per vessel for regions across multiple networks.

RESULTS

Stresses ranged from 0.003 to 2328.1 dyne/cm2 and varied dramatically at the capillary level. For all regions, the maximum segmental shear stresses were for capillary segments. Stresses along proximal capillaries branching from arteriole inlets were increased compared to stresses along capillaries in more distal regions.

CONCLUSIONS

The results highlight the variability of shear stresses along angiogenic capillaries and motivate new discussions on how endothelial cells may respond in vivo to segment-specific microenvironment during angiogenesis.

Exercise induces superoxide and NOX4 contribution in endothelium-dependent dilation in coronary arterioles from a swine model of chronic myocardial ischemia

Exercise training is an effective, nonpharmacologic therapy and preventative measure for ischemic heart disease. While recent studies have examined reactive oxygen species (ROS) as mediators of exercise training-enhanced coronary blood flow, specific oxidants and their sources have yet to be fully elucidated. We investigated the hypothesis that NADPH oxidase (NOX)-derived superoxide anion would contribute to vasodilation effects in the coronary microcirculation of swine and that these effects would be impaired by chronic ischemia and rescued with exercise training. Adult Yucatan miniature swine were instrumented with an ameroid occluder around the proximal left circumflex coronary artery, resulting in a collateral-dependent myocardial region. Eight weeks post-operatively, swine were randomly assigned to either a sedentary or exercise training (treadmill run; 5 days/week for 14 weeks) protocol. Coronary arterioles were isolated from nonoccluded and collateral-dependent myocardial regions and pressure myography was performed. Exercise training resulted in enhanced endothelium-dependent dilation after occlusion. Scavenging of superoxide via the superoxide dismutase (SOD)-mimetic, tempol, attenuated dilation in both nonoccluded and collateral-dependent arterioles of exercise-trained, but not sedentary swine. NOX1/4 inhibition with GKT136901 attenuated dilation after exercise training but only in collateral-dependent arterioles. High performance liquid chromatography revealed that neither ischemia nor exercise training significantly altered basal or bradykinin-stimulated superoxide levels. Furthermore, superoxide production was not attributable to NOX isoforms nor mitochondria. Immunoblot analyses revealed significantly decreased NOX2 protein after exercise with no differences in NOX1, NOX4, p22phox, SOD proteins. Taken together, these data provide evidence that superoxide and NOX4 independently contribute to enhanced endothelium-dependent dilation following exercise training.

Autoregulatory mission impossible: when afferent arterioles lose contractility

The myogenic response of afferent arterioles is a key autoregulatory mechanism that protects the glomeruli from barotrauma. Afferent arteriolar smooth muscle cells contract to increased intraluminal pressure through mechanosensitive cation channels and interactions between integrin and extracellular matrix that trigger calcium-dependent actomyosin contraction. The study by Feng et al. provides evidence supporting the concept that increased matrix metalloproteinase 9 in kidney microvessels of Dahl salt-sensitive rats interferes with integrin-matrix binding and promotes phenotypic transformation of afferent arterioles, causing loss of myogenic constriction and hypertensive nephropathy.

Uveal vascular bed in health and disease: lesions produced by occlusion of the uveal vascular bed and acute uveal ischaemic lesions seen clinically. Paper 2 of 2

From studies on postmortem anatomical descriptions of the uveal vascular bed, it was generally concluded that occlusion of PCA or its branches should not produce an ischemic lesion. However, in vivo studies have recorded that the PCAs and their branches, right down to the terminal choroidal arterioles, and the choriocapillaris, have a segmental distribution in the choroid, and that PCAs and choroidal arteries function as end-arteries. This explains the basis of the occurrence of isolated inflammatory, ischemic, metastatic, and degenerative choroidal lesions, which are usually localized. Thus, in vivo studies have completely revolutionized our concept of the uveal vascular bed in disease.

Retinal vessel caliber and tortuosity and prediction of 5-year incidence of hypertension

PURPOSE

With arterial hypertension as a global risk factor for cerebrovascular and cardiovascular diseases, we examined whether retinal blood vessel caliber and tortuosity assessed by a vessel-constraint network model can predict the incidence of hypertension.

METHODS

The community-based prospective study included 9230 individuals who were followed for 5 years. Ocular fundus photographs taken at baseline were analyzed by a vessel-constraint network model.

RESULTS

Within the 5-year follow-up, 1279 (18.8%) and 474 (7.0%) participants out of 6813 individuals free of hypertension at baseline developed hypertension and severe hypertension, respectively. In multivariable analysis, a higher incidence of hypertension was related to a narrower retinal arteriolar diameter ( P  < 0.001), wider venular diameter ( P  = 0.005), and a smaller arteriole-to-venule diameter ratio ( P  < 0.001) at baseline. Individuals with the 5% narrowest arteriole or the 5% widest venule diameter had a 17.1-fold [95% confidence interval (CI):7.9, 37.2] or 2.3-fold (95% CI: 1.4, 3.7) increased risk for developing hypertension, as compared with those with the 5% widest arteriole or the 5% narrowest venule. The area under the receiver operator characteristic curve for predicting the 5-year incidence of hypertension and severe hypertension was 0.791 (95% CI: 0.778, 0.804) and 0.839 (95% CI: 0.821, 0.856), respectively. Although the venular tortuosity was positively associated with the presence of hypertension at baseline ( P  = 0.01), neither arteriolar tortuosity nor venular tortuosity was associated with incident hypertension (both P  ≥ 0.10).

CONCLUSION AND RELEVANCE

Narrower retinal arterioles and wider venules indicate an increased risk for incident hypertension within 5 years, while tortuous retinal venules are associated with the presence rather than the incidence of hypertension. The automatic assessment of retinal vessel features performed well in identifying individuals at risk of developing hypertension.

Association of Central Retinal Arteriolar and Venular Equivalents with Brain-aging and Macular Ganglion Cell-inner Plexiform Layer Thickness

INTRODUCTION

Neurodegeneration and cognitive decline in aging are growing public health concerns. This study investigates associations between central retinal arteriolar and venular equivalents (CRAE, CRVE) and brain-aging, a sensory and cognitive test composite measure, and macular ganglion cell-inner plexiform layer (mGCIPL) thickness, a biomarker of neurodegeneration.

METHODS

Beaver Dam Offspring Study (BOSS) participants are adult children (baseline (2005-2008) age 21-84 years) of the population-based Epidemiology of Hearing Loss Study participants. Follow-up occurred every 5 years. In 2010-2013, fundus photographs were used to measure retinal vessels. A brain-aging score was constructed by principal component analysis using sensorineural and cognitive data. Associations between incident brain-aging and vessel measures were investigated using logistic regression. Associations between CRAE and CRVE and mGCIPL thickness, measured in 2015-2017, were also investigated.

RESULTS

Participants (N = 2381; mean age: 53.9 years (SD = 9.8); 54% women) had a mean CRAE and CRVE of 148.8 µm (SD = 14.5) and 221.7 µm (SD = 20.7), respectively. Among those without ocular conditions, wider CRAE was associated with decreased 5-year brain-aging risk (33% per SD CRAE increase). Both vessel measures were independently associated with mGCIPL thickness. The mGCIPL thickness increased by approximately 1.7 µm and 2.0 µm per SD increase in CRAE and CRVE, respectively.

DISCUSSION

The association of CRAE with incident brain-aging indicates its potential use as a screening tool among those without eye disease. The associations between CRAE and CRVE and mGCIPL thickness indicate narrower vasculature could affect neuronal health. These associations point to potential usefulness of retinal vessel measurements to identify people at higher risk of sensorineural declines and neurodegeneration.

QUANTITATIVE MORPHOLOGICAL ASPECTS OF THE STUDY OF THE FEATURES OF THE REMODELING OF THE HEMOMICROCIRCULATORY CHANNEL OF THE TESTICLES UNDER THE ACTION OF ALUMINUM CHLORIDE ON THE BODY

OBJECTIVE

The aim: To conduct a morphometric analysis of the features of the remodeling of vessels of the hemomicrocirculatory channel of the testicles under the action of aluminum chloride on the body.

PATIENTS AND METHODS

Materials and methods: The testicles of 52 white male Wistar rats were morphologically studied, which were divided into two groups: intact and animals injected with aluminum chloride at a dose of 100 mg/kg.

RESULTS

Results: The long-term effect of aluminum chloride on the body led to pronounced changes in the quantitative morphological indicators of the vessels of the hemomicrocirculatory channel of the testes compared to the control ones. The diameter of arterioles of the left testicle decreased by 18.4%, precapillary arterioles by 19.1%, hemocapillaries by 10.1%. The diameter of the postcapillary venules of the left testicle increased by 26.3%, the venules by 26.4%, and the density of microvessels decreased by 30.0%, which indicated the deterioration of its blood supply. The degree of remodeling of microvessels in the right testis was less pronounced. The diameter of arterioles of the right testicle decreased by 17.1%, precapillary arterioles by 18.4 %, and hemocapillaris by 9.1%. The diameter of the postcapillary venules of the right testicle increased by 25.5%, the venules by 27.0%, and the density of microvessels decreased by 25.8%.

CONCLUSION

Conclusions: Long-term action (during the month) of aluminum chloride on the body leads to pronounced remodeling of the vessels of the hemomicrocirculatory channel of the testicles, which is characterized by a pronounced narrowing of its supply (arterioles, precapillary arterioles), exchange (hemocapillaries) links.

Prenatal exposure to alcohol impairs responses of cerebral arterioles to activation of potassium channels: Role of oxidative stress

BACKGROUND

Potassium channels play an important role in the basal tone and dilation of cerebral resistance arterioles in response to many stimuli. However, the effect of prenatal alcohol exposure (PAE) on specific potassium channel function remains unknown. The first goal of this study was to determine the influence of PAE on the reactivity of cerebral arterioles to activation of ATP-sensitive potassium (KATP ) and BK channels. Our second goal was to determine whether oxidative stress contributed to potassium channel dysfunction of cerebral arterioles following PAE.

METHODS

We fed Sprague-Dawley dams a liquid diet with or without alcohol (3% EtOH) for the duration of their pregnancy (21 to 23 days). We examined in vivo responses of cerebral arterioles in control and PAE male and female offspring (14 to 16 weeks after birth) to activators of potassium channels (Iloprost [BK channels] and pinacidil [KATP channels]), before and following inhibition of oxidative stress with apocynin.

RESULTS

We found that PAE impaired dilation of cerebral arterioles in response to activation of potassium channels with iloprost and pinacidil, and this impairment was similar in male and female rats. In addition, treatment with apocynin reversed the impaired vasodilation to iloprost and pinacidil in PAE rats to levels observed in control rats. This effect of apocynin also was similar in male and female rats.

CONCLUSIONS

PAE induces dysfunction in the ability of specific potassium channels to dilate cerebral arterioles which appears to be mediated by an increase in oxidative stress. We suggest that these alterations in potassium channel function may contribute to the pathogenesis of cerebral vascular abnormalities and/or behavioral/cognitive deficits observed in fetal alcohol spectrum disorders.

H2O2 Mediates VEGF- and Flow-Induced Dilations of Coronary Arterioles in Early Type 1 Diabetes: Role of Vascular Arginase and PI3K-Linked eNOS Uncoupling

In diabetes, the enzyme arginase is upregulated, which may compete with endothelial nitric oxide (NO) synthase (eNOS) for their common substrate L-arginine and compromise NO-mediated vasodilation. However, this eNOS uncoupling can lead to superoxide production and possibly vasodilator hydrogen peroxide (H₂O₂) formation to compensate for NO deficiency. This hypothesis was tested in coronary arterioles isolated from pigs with 2-week diabetes after streptozocin injection. The NO-mediated vasodilation induced by flow and VEGF was abolished by NOS inhibitor L-NAME and phosphoinositide 3-kinase (PI3K) inhibitor wortmannin but was not affected by arginase inhibitor N^ω-hydroxy-nor-L-arginine (nor-NOHA) or H₂O₂ scavenger catalase in control pigs. With diabetes, this vasodilation was partially blunted, and the remaining vasodilation was abolished by catalase and wortmannin. Administration of L-arginine or nor-NOHA restored flow-induced vasodilation in an L-NAME sensitive manner. Diabetes did not alter vascular superoxide dismutase 1, catalase, and glutathione peroxidase mRNA levels. This study demonstrates that endothelium-dependent NO-mediated coronary arteriolar dilation is partially compromised in early type 1 diabetes by reducing eNOS substrate L-arginine via arginase activation. It appears that upregulated arginase contributes to endothelial NO deficiency in early diabetes, but production of H₂O₂ during PI3K-linked eNOS uncoupling likely compensates for and masks this disturbance.

Unhealthy Lifestyles and Retinal Vessel Calibers among Children and Adolescents: A Systematic Review and Meta-Analysis

The retinal vessel caliber (RVC) is an important biomarker of cardiovascular diseases, which can be semi-automatically measured by fundus photography. This review investigated the associations between the RVCs and the life styles of early life, such as physical activity (PA), sedentary behavior (SB), dietary and sleep, by summarizing the findings from studies on children and adolescents. Two databases (Medline and Embase) were searched from their inception to 30 June 2022. The selected studies were literatures on observational designs, fundus photographs, retinal vessels and lifestyles of children or adolescents. Correlation coefficients of unhealthy life styles and RVCs were transformed to Fisher's z-scores, and the random-effects model was applied to pool data. A total of 18 observational studies were selected; the lifestyles accessed include 9 studies for PA and SB, 8 studies for dietary and 1 study for sleep. The meta-analysis on the correlation coefficients of regression models found the high level of SB (qualified by screen time, ST) was associated the narrower central retinal arteriolar equivalent (CRAE) among children (r = -0.043, 95% confidence intervals [CI] -0.078 to -0.009). By comparing the first and fourth quartiles of PA, the meta-analysis showed that more indoor PA was associated with smaller venular calibers and more outdoor PA was associated with wider CRAE (r = 0.88, 95%CI -3.33 to 0). Unhealthy lifestyles might be harmful on the retinal microcirculation among children and adolescents but their health effect seems not to be as significant as those in adults.

Plasticity of cerebral microvascular structure and mechanics during hypertension and following recovery of arterial pressure

Changes in vascular structure contribute to vascular events and loss of brain health. We examined changes in cerebral arterioles at the onset of hypertension and the hypothesis that alterations during hypertension would recover with the return of mean arterial pressure (MAP) to normal. MAP was measured with radiotelemetry in awake male C57BL/6J mice at baseline and during infusion of vehicle or angiotensin II (ANG II, 1.4 mg/kg/day using osmotic pumps) for 28 days, followed by a 28-day recovery. With ANG II treatment, MAP increased through day 28. On day 30, MAP began to recover, reaching levels not different from vehicle on day 37. We measured intravascular pressure, diameter, wall thickness (WT), wall:lumen ratio (W:L), cross-sectional area (CSA), and slope of the tangential elastic modulus (ET) in maximally dilated arterioles. Variables were similar in both groups at day 1, with no significant change with vehicle treatment. With ANG II treatment, CSA, WT, and W:L increased on days 7-28. Internal and external diameter was reduced at 14 and 28 days. ET versus wall stress was reduced on days 7-28. During recovery, the diameter remained at days 14 and 28 values, whereas other variables returned partly or completely to normal. Thus, CSA, WT, W:L, and ET versus wall stress changed rapidly during hypertension and recovered with MAP. In contrast, inward remodeling developed slowly and did not recover. This lack of recovery has mechanistic implications for the long-term impact of hypertension on vascular determinants of brain health.NEW & NOTEWORTHY Changes in vascular structure contribute to vascular events and loss of brain health. We examined the inherent structural plasticity of cerebral arterioles during and after a period of hypertension. Arteriolar wall thickness, diameter, wall-to-lumen ratio, and biological stiffness changed rapidly during hypertension and recovered with blood pressure. In contrast, inward remodeling developed slowly and did not recover. This lack of recovery of arteriolar diameter has implications for the long-term impact of hypertension on vascular determinants of brain health.

Retinal microvascular associations with cardiometabolic risk factors differ by diabetes status: results from the UK Biobank

AIMS/HYPOTHESIS

The aim of the study was to examine the association of retinal vessel morphometry with BP, body composition and biochemistry, and to determine whether these associations differ by diabetes status.

METHODS

The UK Biobank ocular assessment included 68,550 participants aged 40-70 years who underwent non-mydriatic retinal photography, BP and body composition measurements, and haematological analysis. A fully automated image analysis program provided measurements of retinal vessel diameter and tortuosity. The associations between retinal vessel morphology and cardiometabolic risk factors by diabetes status were examined using multilevel linear regression, to provide absolute differences in vessel diameter and percentage differences in tortuosity (allowing for within-person clustering).

RESULTS

A total of 50,233 participants (a reduction from 68,550) were included in these analyses. Overall, those with diabetes had significantly more tortuous venules and wider arteriolar diameters compared with those without. Associations between venular tortuosity and cardiometabolic risk factors differed according to diabetes status (p interaction <0.01) for total fat mass index, HbA_1c, C-reactive protein, white cell count and granulocyte count. For example, a unit rise in white cell count was associated with a 0.18% increase (95% CI 0.05, 0.32%) in venular tortuosity for those without diabetes and a 1.48% increase (95% CI 0.90, 2.07%) among those with diabetes. For arteriolar diameter, significant interactions were evident for systolic BP, diastolic BP, mean arterial pressure (MAP) and LDL-cholesterol. For example, a 10 mmHg rise in systolic BP was associated with a -0.92 μm difference (95% CI -0.96 to -0.88 μm) in arteriolar diameter for those without diabetes, and a -0.58 μm difference (95% CI -0.76 to -0.41 μm) among those with diabetes. No interactions were observed for arteriolar tortuosity or venular diameters.

CONCLUSIONS/INTERPRETATION

We provide clear evidence of the modifying effect of diabetes on cardiometabolic risk factor associations with retinal microvascular architecture. These observations suggest the occurrence of preclinical disease processes, and may be a sign of impaired autoregulation due to hyperglycaemia, which has been suggested to play a pivotal role in the development of diabetes-related microvascular complications.

DATA AVAILABILITY

The data supporting the results reported here are available through the UK Biobank ( https://www.ukbiobank.ac.uk/enable-your-research/apply-for-access ).

Loss of TRPV2-mediated blood flow autoregulation recapitulates diabetic retinopathy in rats

Loss of retinal blood flow autoregulation is an early feature of diabetes that precedes the development of clinically recognizable diabetic retinopathy (DR). Retinal blood flow autoregulation is mediated by the myogenic response of the retinal arterial vessels, a process that is initiated by the stretch‑dependent activation of TRPV2 channels on the retinal vascular smooth muscle cells (VSMCs). Here, we show that the impaired myogenic reaction of retinal arterioles from diabetic animals is associated with a complete loss of stretch‑dependent TRPV2 current activity on the retinal VSMCs. This effect could be attributed, in part, to TRPV2 channel downregulation, a phenomenon that was also evident in human retinal VSMCs from diabetic donors. We also demonstrate that TRPV2 heterozygous rats, a nondiabetic model of impaired myogenic reactivity and blood flow autoregulation in the retina, develop a range of microvascular, glial, and neuronal lesions resembling those observed in DR, including neovascular complexes. No overt kidney pathology was observed in these animals. Our data suggest that TRPV2 dysfunction underlies the loss of retinal blood flow autoregulation in diabetes and provide strong support for the hypothesis that autoregulatory deficits are involved in the pathogenesis of DR.

Emerging Insights into Glomerular Vascular Pole and Microcirculation

The glomerular vascular pole is the gate for the afferent and efferent arterioles and mesangial cells and a frequent location of peripolar cells with an unclear function. It has been studied in definitive detail for >30 years, and functionally interrogated in the context of signal transduction from the macula densa to the mesangial cells and afferent arteriolar smooth muscle cells from 10 to 20 years ago. Two recent discoveries shed additional light on the vascular pole, with possibly far-reaching implications. One, which uses novel serial section electron microscopy, reveals a shorter capillary pathway between the basins of the afferent and efferent arterioles. Such a pathway, when patent, may short-circuit the multitude of capillaries in the glomerular tuft. Notably, this shorter capillary route is enclosed within the glomerular mesangium. The second study used anti-Thy1.1-induced mesangiolysis and intravital microscopy to unequivocally establish in vivo the long-suspected contractile function of mesangial cells, which have the ability to change the geometry and curvature of glomerular capillaries. These studies led me to hypothesize the existence of a glomerular perfusion rheostat, in which the shorter path periodically fluctuates between being more and less patent. This action reduces or increases blood flow through the entire glomerular capillary tuft. A corollary is that the GFR is a net product of balance between the states of capillary perfusion, and that deviations from the balanced state would increase or decrease GFR. Taken together, these studies may pave the way to a more profound understanding of glomerular microcirculation under basal conditions and in progression of glomerulopathies.

Mineralocorticoid receptor antagonism improves transient receptor potential vanilloid 4-dependent dilation of cerebral parenchymal arterioles and cognition in a genetic model of hypertension

OBJECTIVE

In a model of secondary hypertension, mineralocorticoid receptor (MR) antagonism during the development of hypertension prevents the impairment of transient receptor potential vanilloid 4 (TRPV4) activation in parenchymal arterioles (PAs) and cognitive impairment. However, it is unknown whether MR antagonism can improve these impairments when treatment begins after the onset of essential hypertension. We tested the hypothesis that MR activation in stroke-prone spontaneously hypertensive rats (SHRSP) leads to impaired TRPV4-mediated dilation in PAs that is associated with cognitive dysfunction and neuroinflammation.

METHODS

20-22-week-old male SHRSP ± eplerenone (EPL; 100 mg/kg daily for 4 weeks) were compared to normotensive Sprague-Dawley (SD) rats. Pressure myography was used to assess PA function. Cognition was tested using Y-maze. Neuroinflammation was assessed using immunofluorescence and qRT-PCR.

RESULTS

Carbachol-mediated endothelium-dependent dilation was impaired in SHRSP, and MR antagonism improved this without affecting myogenic tone. Dilation to TRPV4 agonist GSK1016790A was impaired in SHRSP, and ELP treatment restored this. Intermediate conductance potassium channel (IKCa)/small conductance potassium channel (SKCa)-mediated dilation was impaired by hypertension and unaffected by EPL treatment. TRPV4 and IKCa/SKCa channel mRNA expression were reduced in PAs from hypertensive rats, and EPL did not improve this. Impairments in PA dilation in SHRSP were associated with cognitive decline, microglial activation, reactive astrogliosis, and neuroinflammation; cognitive and inflammatory changes were improved with MR blockade.

CONCLUSIONS

These data advance our understanding of the effects of hypertension on cerebral arterioles using a clinically relevant model and treatment paradigm. Our studies suggest TRPV4 and the MR are potential therapeutic targets to improve cerebrovascular function and cognition during hypertension.

Retinal Vascular Caliber in Coronary Heart Disease and Its Risk Factors

BACKGROUND

Many clinical and experimental articles have suggested that the retinal vascular diameter can be used as a predictor of coronary heart disease (CHD). However, the results and reliability of the prediction are still controversial.

OBJECTIVE

A meta-analysis of observational study was conducted to clarify the relationships of retinal vessel caliber with CHD and CHD risk factors.

METHOD

PubMed and Embase were searched for all observational studies on the relationship of retinal vessel caliber with CHD and CHD risk factors from 2001 to 2021. The meta-analysis has been registered in PROSPERO (registration number is CRD42021267154).

RESULT

A total of 14 articles were selected for the inclusion in this meta-analysis. In the primary outcome, smaller retinal arteriolar caliber was related to CHD, and the results achieved statistical significance (MD: -5.55, 95% CI: -8.07 to -3.02, p < 0.0001), while there was no significant difference in vein caliber between CHD and healthy people (MD: 1.10, 95% CI: -3.55 to 5.76, p = 0.64 > 0.05). Smaller retinal arteriolar caliber was related to increasing age, male sex, bigger BMI, and hypertension. Bigger retinal arteriolar caliber was related to current smoking. Smaller retinal venule caliber was related to increasing age and hypertension. Bigger retinal venule caliber was related to current smoking, bigger BMI, and diabetes.

CONCLUSION

Smaller retinal arteriolar caliber was related to CHD, while there was no significant difference in venule caliber between CHD and healthy people. Retinal vascular caliber also independently related to CHD risk factors (e.g., age, gender, smoke, BMI, hypertension, and diabetes).

In-vivo assessment of retinal vessel diameters and observer variability in mice: A methodological approach

Background

Central retinal arteriolar (CRAE) and venular (CRVE) diameter equivalents are predictive for cardiovascular and all-cause mortality in humans. The aim of this study was to investigate the inter- and intraobserver variability for the assessment of CRAE and CRVE in mice using fluorescein contrast enhancement as compared to crude analysis.

Methods

Three high quality images with (F) and without fluorescein (NF) of eight mice (type C57BL) were recorded and analysed by two independent experienced investigators to investigate interobserver variability. In addition, one investigator analysed 20 F and 20 NF images twice to investigate intraobserver variability. The time course of CRAE and CRVE vessel responses after fluorescein injection were recorded in one mouse every 30 seconds for 15 minutes.

Results

The interobserver variability was lower in F images compared to NF images for CRAE (r = 0.99, p < 0.001 vs. r = 0.65, p = 0.083) and CRVE (r = 0.99, p < 0.001 vs. r = 0.79, p = 0.019). Intraobserver variability for CRAE (r = 0.99, p < 0.001 vs. r = 0.48, p = 0.032) and CRVE (r = 0.98, p < 0.001 vs. r = 0.86, p < 0.001) were lower in F compared to NF images. Fluorescein injection induced vascular staining mimicking vessel dilation (+14%) followed by a long-lasting stable staining phase well suited for precise measurements.

Conclusions

Measurement variability can be optimized by use of fluorescein as contrast enhancement in mice. Standardization for time of image acquisition after fluorescein injection is advisable. Translation of static retinal vessel analysis into a rodent model has the potential to bridge the research gap between proof of concept studies in animals and clinical studies in humans.

βENaC and ASIC2 associate in VSMCs to mediate pressure-induced constriction in the renal afferent arteriole

In independent studies, our laboratory has shown the importance of the degenerin proteins β-epithelial Na+ channel (βENaC) and acid-sensing ion channel 2 (ASIC2) in pressure-induced constriction (PIC) in renal interlobar arteries. Most, but not all, of the PIC response is abolished in mice lacking normal levels of βENaC or in ASIC2-null mice, indicating that the functions of βENaC and ASIC2 cannot fully compensate for the loss of the other. Degenerin proteins are known to associate and form heteromeric channels in expression systems, but whether they interact biochemically and functionally in vascular smooth muscle cells is unknown. We hypothesized that βENaC and ASIC2 interact to mediate PIC responses in renal vessels. To address this possibility, we 1) used biochemical approaches to show that βENaC associates into high-molecular-weight complexes and immunoprecipitants with ASIC2 in vascular smooth muscle cells and then 2) examined PIC in renal afferent arterioles in mice lacking normal levels of βENaC (βENaCm/m) or/and ASIC2 (ASIC2-/-) using the isolated afferent arteriole-attached glomerulus preparation. We found that the sensitivity of the PIC response (slope of the relationship between intraluminal pressure and percent myogenic tone) decreased to 26%, 27%, and -8% of wild-type controls in ASIC2-/-, βENaCm/m, and ASIC2-/-/βENaCm/m groups, respectively, suggesting that the PIC response was totally abolished in mice deficient in both ASIC2 and βENaC. Surprisingly, we found that resting internal diameters were 20-30% lower (60 mmHg, Ca2+ free) in ASIC2-/-/βENaCm/m (11.3 ± 0.5 µm) mice compared with control (14.4 ± 0.6 µm, P = 0.0007, independent two-tailed t test) or singly modified (15.7 ± 1.0 to 16.3 ± 1.1 µm) mice, suggesting compensatory vasoconstriction or remodeling. We then examined mean arterial blood pressure (MAP) using radiotelemetry and glomerular injury using histological examination of renal sections. We found that 24-h MAP was mildly elevated (+8 mmHg) in ASIC2-/-/βENaCm/m mice versus wild-type controls and the glomerular injury score was modestly increased by 38%. These findings demonstrate that myogenic constriction in afferent arterioles is dependent on normal expression of βENaC and ASIC2 and that mice lacking normal levels of ASIC2 and βENaC have mild renal injury and increased MAP.NEW & NOTEWORTHY Transmission of systemic blood pressure to delicate renal microvessels is a primary determinant of vascular injury in chronic kidney disease progression to end-stage renal disease. Here, we identified two degenerin family members, with an evolutionary link to mechanosensing, that interact biochemically and functionally to regulate systemic blood pressure and renal injury. Thus, degenerin proteins may serve as a target for the development of therapies to prevent or delay renal disease progression.

PEG-LEG ARTERIOLES: AN ADAPTATION TO CHRONIC RETINAL HYPOPERFUSION

PURPOSE

To describe a heretofore unreported retinal vascular sign related to chronic retinal hypoperfusion.

METHODS

A case report of a 42-year-old woman who was found to have a novel pattern of retinal vascular remodeling in the setting of severe bilateral occlusive disease of the carotid and vertebral arteries.

RESULTS

The patient had a childhood history of nasopharyngeal carcinoma, treated with external beam radiation. At age 35, she suffered bilateral occipital infarctions. A cerebral angiogram showed complete occlusion of both common carotid arteries and complete occlusion of the proximal segments of both vertebral arteries. Seven years after her stroke, examination of her fundus revealed a remarkable pattern of vascular remodeling that involved nearly all of the major retinal arterioles in both eyes. In each vessel, a narrowed proximal segment abruptly dilated to a larger-than-normal caliber at a distance of 1 to 2 disk diameters from the optic disk. The abnormally increased caliber extended into the retinal periphery.

CONCLUSION

Chronic severe retinal hypoperfusion due to profound carotid occlusive disease can lead to adaptive remodeling of the retinal vasculature in a pattern that closely resembles the iconic image of a pirate's peg leg.

Impaired microcirculatory function, mitochondrial respiration, and oxygen utilization in skeletal muscle of claudicating patients with peripheral artery disease

Peripheral artery disease (PAD) is an atherosclerotic disease that impairs blood flow and muscle function in the lower limbs. A skeletal muscle myopathy characterized by mitochondrial dysfunction and oxidative damage is present in PAD; however, the underlying mechanisms are not well established. We investigated the impact of chronic ischemia on skeletal muscle microcirculatory function and its association with leg skeletal muscle mitochondrial function and oxygen delivery and utilization capacity in PAD. Gastrocnemius samples and arterioles were harvested from patients with PAD (n = 10) and age-matched controls (Con, n = 11). Endothelium-dependent and independent vasodilation was assessed in response to flow (30 μL·min-1), acetylcholine, and sodium nitroprusside (SNP). Skeletal muscle mitochondrial respiration was quantified by high-resolution respirometry, microvascular oxygen delivery, and utilization capacity (tissue oxygenation index, TOI) were assessed by near-infrared spectroscopy. Vasodilation was attenuated in PAD (P < 0.05) in response to acetylcholine (Con: 71.1 ± 11.1%, PAD: 45.7 ± 18.1%) and flow (Con: 46.6 ± 20.1%, PAD: 29.3 ± 10.5%) but not SNP (P = 0.30). Complex I + II state 3 respiration (P < 0.01) and TOI recovery rate were impaired in PAD (P < 0.05). Both flow and acetylcholine-mediated vasodilation were positively associated with complex I + II state 3 respiration (r = 0.5 and r = 0.5, respectively, P < 0.05). Flow-mediated vasodilation and complex I + II state 3 respiration were positively associated with TOI recovery rate (r = 0.8 and r = 0.7, respectively, P < 0.05). These findings suggest that chronic ischemia attenuates skeletal muscle arteriole endothelial function, which may be a key mediator for mitochondrial and microcirculatory dysfunction in the PAD leg skeletal muscle. Targeting microvascular dysfunction may be an effective strategy to prevent and/or reverse disease progression in PAD.NEW & NOTEWORTHY Ex vivo skeletal muscle arteriole endothelial function is impaired in claudicating patients with PAD, and this is associated with attenuated skeletal muscle mitochondrial respiration. In vivo skeletal muscle oxygen delivery and utilization capacity is compromised in PAD, and this may be due to microcirculatory and mitochondrial dysfunction. These results suggest that targeting skeletal muscle arteriole function may lead to improvements in skeletal muscle mitochondrial respiration and oxygen delivery and utilization capacity in claudicating patients with PAD.

Longitudinal assessment of spiral artery and intravillous arteriole blood flow and adverse pregnancy outcome

OBJECTIVE

Superb microvascular imaging (SMI) has been shown to improve visualization of small vessels by suppressing global motions while preserving low-flow components, such as the microvessels in the placenta. We sought to determine if SMI-aided visualization of flow velocity waveforms in the spiral arteries (SA) and intravillous fetal arterioles (IVA) could predict fetal growth restriction (FGR), gestational hypertension (GH) and/or pre-eclampsia (PE).

METHODS

This was a prospective longitudinal study of singleton pregnancies without fetal anomaly, receiving prenatal care in one of two medical centers over a 5-year period. Using SMI-aided color Doppler, SA and IVA flow velocity was measured at three timepoints: 11 + 0 to 14 + 0, 18 + 0 to 22 + 6 and 28 + 0 to 34 + 6 weeks of gestation. SA and IVA flow velocity waveforms were reported as resistance indices (RI). RI values were analyzed using multilevel modeling; individual regression curves were estimated and combined to obtain the reference intervals for SA-RI and IVA-RI in uncomplicated pregnancies. The primary clinical outcome was FGR and secondary outcomes were PE and GH. FGR was defined as estimated fetal weight < 10^th percentile. Student's t-test was used to compare deviation from expected RI between normal and complicated pregnancies.

RESULTS

Among 540 pregnancies included in the analysis, 18 (3.3%) had FGR, 31 (5.7%) PE and 61 (11.3%) GH. In uncomplicated pregnancies, the SA-RI decreased progressively with advancing gestation, whereas the IVA-RI increased with gestational age. In the third trimester, the mean SA-RI and IVA-RI values were significantly higher in the FGR group compared with pregnancies that did not develop FGR, while the mean SA-RI was significantly higher in PE compared with non-PE pregnancies. There was no significant difference in mean SA-RI or IVA-RI between pregnancies with vs those without GH at any gestational age. When all three adverse outcomes were combined, SA-RI was significantly higher in pregnancies with these outcomes when compared to uncomplicated pregnancies in the third trimester (mean ± SD, 0.29 ± 0.12 vs 0.26 ± 0.12; P = 0.02). In screening for FGR using SA-RI, the areas under the receiver-operating-characteristics curves (AUC) were 0.68, 0.73 and 0.73 in the first, second and third trimesters, respectively. The respective AUCs for IVA-RI were 0.72, 0.72 and 0.73 for each trimester.

CONCLUSIONS

SA-RI and IVA-RI, measured using SMI technology, were significantly higher in pregnancies at risk for FGR in late gestation. Larger studies are needed to determine if SA and IVA flow are reliable predictors of adverse pregnancy outcome. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

[Relationship of retinal vascular caliber with age and cardiometabolic diseases in the population over 50 years of age]

In an aging society, age-dependent diseases with high mortality, including cardiovascular diseases (CVD) and type 2 diabetes mellitus (DM2), occupy a special place. There is only limited population-based data on the relationship between cardiometabolic diseases and target-organ damage, including ocular microvasculature.

PURPOSE

To explore the associations between the caliber of retinal vessels and cardiometabolic diseases in a population sample of men and women from middle-aged to elderly (Novosibirsk).

MATERIAL AND METHODS

The subjects were participants of the Russian cohort - part of the international project HAPIEE, and were initially examined in 2003-2005 (n=9360, aged 45-69 years, Novosibirsk). At the third survey in 2015-2017, a random sub-sample of men and women (n=1011) was formed for an in-depth evaluation. We performed a calibrometric analysis involving measurement of central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and CRAE-to-CRVE ratio (AVR).

RESULTS

In a population sample of men and women aged 55-84 years, age increment is accompanied by a decrease in the calibers of retinal arterioles and venules (p<0.001). Arterial hypertension (AH) was accompanied by a decrease in CRAE, CRVE (p=0.001) and AVR (p<0.001); the associations between AH, CRAE and AVR were independent from other factors. Multivariate analysis showed that CRAE and CRVE were inversely associated with the presence of DM2 (p=0.026). Carotid atherosclerosis was accompanied by an increase in CRVE (p<0.002); this relationship was mainly attributed to age and metabolic factors. There were no associations between carotid atherosclerosis and either CRAE or AVR. The multivariate analysis identified the weak positive associations of CRAE and AVR with the presence of ischemic heart disease and CVD.

CONCLUSION

In the examined population sample aged 55-84 years, a number of associations were detected between retinal vascular caliber and cardiometabolic diseases. The observed changes in the microvascular bed of the retina may be important for prognosis of the course of common cardiometabolic diseases.

Scavenging Free Iron Reduces Arteriolar Microvasospasms After Experimental Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Subarachnoid hemorrhage (SAH) is associated with acute and delayed cerebral ischemia resulting in high acute mortality and severe chronic neurological deficits. Spasms of the pial and intraparenchymal microcirculation (microvasospasms) contribute to acute cerebral ischemia after SAH; however, the underlying mechanisms remain unknown. We hypothesize that free iron (Fe3+) released from hemolytic red blood cells into the subarachnoid space may be involved in microvasospasms formation.

METHODS

Male C57BL/6 mice (n=8/group) received 200 mg/kg of the iron scavenger deferoxamine or vehicle intravenously and were then subjected to SAH by filament perforation. Microvasospasms of pial and intraparenchymal vessels were imaged three hours after SAH by in vivo 2-photon microscopy.

RESULTS

Microvasospasms occurred in all investigated vessel categories down to the capillary level. Deferoxamine significantly reduced the number of microvasospasms after experimental SAH. The effect was almost exclusively observed in larger pial arterioles (>30 µm) covered with blood.

CONCLUSIONS

These results provide proof-of-principle evidence that Fe3+ is involved in the formation of arteriolar microvasospasms after SAH and that arteriolar and capillary microvasospasms are triggered by different mechanisms. Deciphering the mechanisms of Fe3+-induced microvasospasms may result in novel therapeutic strategies for SAH patients.

Changes in retinal vascular diameters in senior and geriatric cats in association with variation in systemic blood pressure

OBJECTIVES

Early diagnosis of arterial hypertension is essential to prevent target organ damage. In humans, retinal arteriolar narrowing predicts hypertension. This blinded prospective observational study investigated the retinal vessel diameters in senior and geriatric cats of varying systolic blood pressure (SBP) status and evaluated retinal vascular changes in hypertensive cats after treatment.

METHODS

Cats with a median age of 14 years (range 9.1-22 years) were categorised into five groups: group 1, healthy normotensive (SBP <140 mmHg; n = 40) cats; group 2, pre-hypertensive (SBP 140-160 mmHg; n = 14) cats; group 3, cats with chronic kidney disease (CKD) and normotensive (n = 26); group 4, cats with CKD and pre-hypertensive (n = 13); and group 5, hypertensive cats (SBP >160 mmHg, n = 15). Colour fundus images (Optibrand ClearView) were assessed for hypertensive lesions. Retinal vascular diameters and bifurcation angles were annotated and calculated using the Vascular Assessment and Measurement Platform for Images of the Retina annotation tool (VAMPIRE-AT). When available, measurements were obtained at 3 and 6 months after amlodipine besylate treatment.

RESULTS

Ten hypertensive cats had retinal lesions, most commonly intraretinal haemorrhages and retinal exudates. Arteriole and venule diameters decreased significantly with increasing age (-0.17 ± 0.05 pixels/year [P = 0.0004]; -0.19 ± 0.05 pixels/year). Adjusted means ± SEM for arteriole and venule diameter (pixels) were 6.3 ± 0.2 and 8.9 ± 0.2 (group 1); 7.6 ± 0.3 and 10.1 ± 0.4 (group 2); 6.9 ± 0.2 and 9.5 ± 0.3 (group 3); 7.4 ± 0.3 and 10.0 ± 0.4 (group 4); and 7.0 ± 0.3 and 9.8 ± 0.4 (group 5). Group 1 arteriole and venule diameters were significantly lower than those of groups 2 and 4. Group 2 arteriole bifurcation angle was significantly narrower than those of groups 1 and 3. Post-treatment, vessel diameters decreased significantly at 3 and 6 months in seven hypertensive cats.

CONCLUSIONS AND RELEVANCE

Increased age was associated with reduced vascular diameters. Longitudinal studies are required to assess if vessel diameters are a risk indicator for hypertension in cats.

Prolonged mechanical ventilation increases diaphragm arteriole circumferential stretch without changes in stress/stretch: Implications for the pathogenesis of ventilator-induced diaphragm dysfunction

INTRODUCTION

Prolonged mechanical ventilation (MV; ≥6 h) results in large, time-dependent reductions in diaphragmatic blood flow and shear stress. We tested the hypothesis that MV would impair the structural and material properties (ie, increased stress/stretch relation and/or circumferential stretch) of first-order arterioles (1A) from the medial costal diaphragm.

METHODS

Shear stress was estimated from isolated arterioles and prior blood flow data from the diaphragm during spontaneous breathing (SB) and prolonged MV (6 h MV). Thereafter, female Sprague-Dawley rats (~5 months) were randomly divided into two groups, SB (n = 6) and 6 h MV (n = 6). Following SB and 6 h MV, 1A medial costal diaphragm arterioles were isolated, cannulated, and subjected to stepwise (0-140 cmH2 O) increases in intraluminal pressure in calcium-free Ringer's solution. Inner diameter and wall thickness were measured at each pressure step and used to calculate wall:lumen ratio, Cauchy-stress, and circumferential stretch.

RESULTS

Compared to SB, there was a ~90% reduction in arteriolar shear stress with prolonged MV (9 ± 2 vs 78 ± 20 dynes/cm2 ; p ≤ .05). In the unloaded condition (0 cmH2 O), the arteriolar intraluminal diameter was reduced (37 ± 8 vs 79 ± 13 μm) and wall:lumen ratio was increased (120 ± 18 vs 46 ± 10%) compared to SB (p ≤ .05). There were no differences in the passive diameter responses or the circumferential stress/stretch relationship between groups (p > .05), but at each pressure step, circumferential stretch was increased with 6 h MV vs SB (p ≤ .05).

CONCLUSION

During prolonged MV, medial costal diaphragm arteriolar shear stress is severely diminished. Despite no change in the material behavior (stress/stretch), prolonged MV resulted in altered structural and mechanical properties (ie, elevated circumferential stretch) of medial costal diaphragm arterioles. This provides important novel mechanistic insights into the impaired diaphragm blood flow capacity and vascular dysfunction following prolonged MV.

Intravital assessment of precapillary pulmonary arterioles of type 1 diabetic mice shows oxidative damage and increased tone in response to NOS inhibition

Microvascular dilation, important for peripheral tissue glucose distribution, also modulates alveolar perfusion and is inhibited by loss of bioavailable nitric oxide (NO) in diabetes mellitus (DM). We hypothesized that DM-induced oxidative stress decreases bioavailable NO and pulmonary precapillary arteriolar diameter, causing endothelial injury. We examined subpleural pulmonary arterioles after acute NO synthase (NOS) inhibition with NG-nitro-l-arginine methyl ester (l-NAME) in streptozotocin (STZ)- and saline (CTRL)-treated C57BL/6J mice. Microvascular changes were assessed by intravital microscopy in the right lung of anesthetized mice with open chest and ventilated lungs. Arteriolar tone in pulmonary arterioles (27.2-48.7 µm diameter) increased in CTRL mice (18.0 ± 11% constriction, P = 0.034, n = 5) but decreased in STZ mice (13.6 ± 7.5% dilation, P = 0.009, n = 5) after l-NAME. Lung tissue dihydroethidium (DHE) fluorescence (superoxide), inducible NOS expression, and protein nitrosylation (3-nitrotyrosine) increased in STZ mice and correlated with increased glucose levels (103.8 ± 8.8 mg/dL). Fluorescently labeled fibrinogen administration and fibrinogen immunostaining showed fibrinogen adhesion, indicating endothelial injury in STZ mice. In CTRL mice, vasoconstriction to l-NAME was likely due to the loss of bioavailable NO. Vasodilation in STZ mice may be due to decreased formation of a vasoconstrictor or emergence of a vasodilator. These findings provide novel evidence that DM targets the pulmonary microcirculation and that decreased NO bioavailability and increased precapillary arteriolar tone could potentially lead to ventilation-perfusion abnormalities, exacerbating systemic DM complications.NEW & NOTEWORTHY Diabetes pulmonary and microvascular consequences are well recognized but have not been characterized. We assessed lung microvascular changes in a live anesthetized mouse model of type 1 diabetes, using a novel intravital microscopy technique. Our results show new evidence that a diabetes-induced decrease in lung nitric oxide bioavailability underlies oxidative damage, enhanced platelet activation, and endothelial injury causing pulmonary microvascular dysfunction and altered vasoreactivity. These findings could provide novel strategies to prevent or reverse diabetes systemic consequences.

The association between markers of inflammation and retinal microvascular parameters: A systematic review and meta-analysis

BACKGROUND AND AIMS

Adverse changes to the microcirculation play an important role in the pathogenesis of cardiovascular disease (CVD), and inflammation is a key causal mechanism. We investigated the relationship between inflammatory markers and retinal microvascular parameters.

METHODS

Studies up to April 2021 were identified in Medline, Embase and PubMed with the following terms: retinal microvascular parameters, inflammatory markers, and observational studies. Correlation coefficients of inflammatory markers and retinal vascular caliber were pooled using the random-effects model.

RESULTS

Of 4783 studies identified, 36 met the inclusion criteria (general population 26, patients with diseases 10). C-reactive protein (CRP) and white blood cell count (WBC) were most frequently reported. We conducted meta-analysis with 12 CRP studies (22422 participants) and six WBC studies (15209 participants), and also performed a narrative review of all studies. There was consistent evidence of a modest association between CRP and venular caliber (r = 0.09, 95%CI 0.05 to 0.12), but little evidence of an association between CRP with retinal arteriolar caliber (r = 0.00, 95%CI -0.02 to 0.02). Similarly, WBC had stronger associations with venular (r = 0.18, 95%CI 0.05 to 0.31) than arteriolar caliber (r = 0.05, 95%CI 0.01 to 0.09). Narrative review of other inflammatory markers showed consistent findings. There was little evidence of associations between inflammation markers and other microvascular parameters, fractal dimension and tortuosity.

CONCLUSIONS

There was more evidence for an association of inflammation with retinal venular than with arterial caliber. The findings suggest a potential druggable mechanism contributing to microvascular damage that has been relatively overlooked in CVD pathogenesis and treatment.

[Reinterpretation of the Malpighian body in light of the existence of a single glomerular arteriole (Trabucco and Marquez)]

INTRODUCTION

In 1842 William Bowman described the microvascular system of the Malpighian body. Electron microscopic studies definitively revealed the spatial structure of its mesangial-capillary-epithelial component. In 1952-54 Trabucco and Marquez challenged the ideas of Bowman, demonstrating the existence of a single glomerular arteriole. Our study supports the finding of a single glomerular arteriole, leading to a definitive interpretation of the Malpighian body structure.

MATERIALS AND METHODS

Serial histological studies were carried out of the vascular pole in a case of oligomeganephrotic renal hypoplasia and the immunohistochemical study of embryonal glomerular development (15 embryos aged between 7 and 11weeks), with alpha-actin (smooth muscle marker), CD31 and CD34 (endothelial markers) and CD10 (podocyte marker).

RESULTS

The study of the glomerular vascular pole in the case of oligomeganephrotic renal hypoplasia supports the existence of a single glomerular arteriole. Our immunohistochemical study confirmed this finding and provided data on the morphogenesis of the mesangial-capillary-epithelial component of the Malpighian body.

CONCLUSIONS

There exist a single glomerular arteriole. Mesangial and endothelial cells originating from a single glomerular arteriole interact with an epithelial component derived from the nephrogenic vesicle which then generate the lobular glomerular tuft, providing the basis for a definitive interpretation of the structure of the Malpighian body. There is no scientific base to the interpretation of the glomerular microvascular system as having two glomerular arterioles with an intercalated capillary network.

Pharmacologic targeting of Cdc42 GTPase by a small molecule Cdc42 activity-specific inhibitor prevents platelet activation and thrombosis

Gene targeting of Cdc42 GTPase has been shown to inhibit platelet activation. In this study, we investigated a hypothesis that inhibition of Cdc42 activity by CASIN, a small molecule Cdc42 Activity-Specific INhibitor, may down regulate platelet activation and thrombus formation. We investigated the effects of CASIN on platelet activation in vitro and thrombosis in vivo. In human platelets, CASIN, but not its inactive analog Pirl7, blocked collagen induced activation of Cdc42 and inhibited phosphorylation of its downstream effector, PAK1/2. Moreover, addition of CASIN to washed human platelets inhibited platelet spreading on immobilized fibrinogen. Treatment of human platelets with CASIN inhibited collagen or thrombin induced: (a) ATP secretion and platelet aggregation; and (b) phosphorylation of Akt, ERK and p38-MAPK. Pre-incubation of platelets with Pirl7, an inactive analog of CASIN, failed to inhibit collagen induced aggregation. Washing of human platelets after incubation with CASIN eliminated its inhibitory effect on collagen induced aggregation. Intraperitoneal administration of CASIN to wild type mice inhibited ex vivo aggregation induced by collagen but did not affect the murine tail bleeding times. CASIN administration, prior to laser-induced injury in murine cremaster muscle arterioles, resulted in formation of smaller and unstable thrombi compared to control mice without CASIN treatment. These data suggest that pharmacologic targeting of Cdc42 by specific and reversible inhibitors may lead to the discovery of novel antithrombotic agents.

Decreased parenchymal arteriolar tone uncouples vessel-to-neuronal communication in a mouse model of vascular cognitive impairment

Chronic hypoperfusion is a key contributor to cognitive decline and neurodegenerative conditions, but the cellular mechanisms remain ill-defined. Using a multidisciplinary approach, we sought to elucidate chronic hypoperfusion-evoked functional changes at the neurovascular unit. We used bilateral common carotid artery stenosis (BCAS), a well-established model of vascular cognitive impairment, combined with an ex vivo preparation that allows pressurization of parenchymal arterioles in a brain slice. Our results demonstrate that mild (~ 30%), chronic hypoperfusion significantly altered the functional integrity of the cortical neurovascular unit. Although pial cerebral perfusion recovered over time, parenchymal arterioles progressively lost tone, exhibiting significant reductions by day 28 post-surgery. We provide supportive evidence for reduced adenosine 1 receptor-mediated vasoconstriction as a potential mechanism in the adaptive response underlying the reduced baseline tone in parenchymal arterioles. In addition, we show that in response to the neuromodulator adenosine, the action potential frequency of cortical pyramidal neurons was significantly reduced in all groups. However, a significant decrease in adenosine-induced hyperpolarization was observed in BCAS 14 days. At the microvascular level, constriction-induced inhibition of pyramidal neurons was significantly compromised in BCAS mice. Collectively, these results suggest that BCAS uncouples vessel-to-neuron communication-vasculo-neuronal coupling-a potential early event in cognitive decline.

[MORPHOMETRIC ASSESSMENT OF PECULIARITIES OF BLOOD VESSELS OF THE TESTIS IN EXPERIMENTAL ANIMALS AT ARTERIAL HYPERTENSION IN A LITTLE CIRCLE OF CIRCULATION]

Aim of the research - to study the features of the structural reconstruction of blood vessels of the testes of experimental animals at arterial hypertension in the pulmonary circulation using a complex of morphological methods. Experiments were carried out on 78 laboratory sexually mature white male rats, which were divided into 3 groups. The 1 group included 15 intact practically healthy animals, 2 - 48 rats with hypertension in the pulmonary circulation and compensated cor pulmonale, 15 animals with pulmonary hypertension, which developed decompensation of cor pulmonale, constituted the 3 group. Arterial hypertension in the pulmonary circulation was simulated by performing a right-sided pulmonectomy. Three months after the beginning of the experiment, the rats were euthanized by bloodletting under thiopental anesthesia. Histological micropreparations were made from the testes, on which the morphometry of arteries, veins, and microvessels was performed. Quantitative indicators were processed statistically. It was revealed that postresection hypertension in the pulmonary circulation leads to structural reconstruction of arteries, microvessels, and the venous bed of the left and right testes. At the same time, the degree of remodeling of the studied vessels dominates in the microhemocirculatory bed of the left testis at decompensation of the cor pulmonale. Structural reconstruction of the vessels of the microhemocirculatory bed of the testes in case of insufficiency of the cor pulmonary is characterized by a pronounced narrowing of the arterioles, precapillary arterioles), exchange (hemocapillaries) links of the microhemocirculatory bed and the expansion of postcapillary venules and venules, venous plethora, hypoxia, impaired trophism and metabolism, dystrophy, necrobiosis of cells, tissues, infiltration and sclerosis.

Propofol But Not Desflurane Maintains Rat Cerebral Arteriolar Responses to Acetylcholine During Acute Hyperglycemia

BACKGROUND

Acute hyperglycemia causes vascular endothelial dysfunction in various organs including the cerebral vessels. It is associated with increased mortality and morbidity in the perioperative period. The impact of anesthetic agents on cerebral vasodilatory responses during hyperglycemia remains unclear. We investigated endothelial function in rat cerebral arterioles during acute hyperglycemia, under propofol or desflurane anesthesia.

MATERIALS AND METHODS

A closed cranial window preparation was used to measure changes in pial arteriole diameter induced by topical application of acetylcholine (ACh), an endothelium-dependent vasodilator, in rats anesthetized with propofol or desflurane. Pial arteriole responses to ACh were measured during normoglycemia and hyperglycemia. We then investigated whether the response of cerebral arterioles to acute hyperglycemia under propofol anesthesia were related to propofol or its vehicle, intralipid.

RESULTS

ACh resulted in a dose-dependent dilation of cerebral arterioles during propofol and desflurane anesthesia under normoglycemic conditions. The vasodilatory effects of ACh were also maintained under hyperglycemic conditions during propofol anesthesia, but the vasodilator response to ACh was significantly impaired during hyperglycemia compared with normoglycemia with desflurane anesthesia. The vasodilatory effects of ACh were maintained during normoglycemia and hyperglycemia in rats receiving propofol or intralipid.

CONCLUSIONS

Rat pial arteriole responses to ACh are maintained during conditions of acute hyperglycemia with propofol anesthesia but suppressed compared with normoglycemia with desflurane anesthesia.

A systematic review and participant-level meta-analysis found little association of retinal microvascular caliber with reduced kidney function

Previously, variation in retinal vascular caliber has been reported in association with chronic kidney disease (CKD) but findings remain inconsistent. To help clarify this we conducted individual participant data meta-analysis and aggregate data meta-analysis on summary estimates to evaluate cross-sectional associations between retinal vascular caliber and CKD. A systematic review was performed using Medline and EMBASE for articles published until October 2018. The aggregate analysis used a two-stage approach combining summary estimates from eleven studies (44,803 patients) while the individual participant analysis used a one-stage approach combining raw data from nine studies (33,222 patients). CKD stages 3-5 was defined as an estimated glomerular filtration rate under 60 mL/min/1.73m2. Retinal arteriolar and venular caliber (central retinal arteriolar and venular equivalent) were assessed from retinal photographs using computer-assisted methods. Logistic regression estimated relative risk of CKD stages 3-5 associated with a 20 μm decrease (approximately one standard deviation) in central retinal arteriolar and venular equivalent. Prevalence of CKD stages 3-5 was 11.2% of 33,222 and 11.3% of 44,803 patients in the individual participant and aggregate data analysis, respectively. No significant associations were detected in adjusted analyses between central retinal arteriolar and venular equivalent and CKD stages 3-5 in the aggregate analysis for central retinal arteriolar relative risk (0.98, 95% confidence interval 0.94-1.03); venular equivalent (0.99, 0.95-1.04) or individual participant central retinal arteriolar (0.99, 0.95-1.04) or venular equivalent (1.01, 0.97-1.05). Thus, meta-analysis provided little evidence to suggest that cross sectional direct measurements of retinal vascular caliber was associated with CKD stages 3-5 in the general population. Hence, meta-analyses of longitudinal studies evaluating the association between retinal parameters and CKD stages 3-5 may be warranted.

[Age-related characteristics of retinal vessels in aging (literature review).]

The changes of retinal vascular caliber and microvascular topography reflect the cumulative response to ageing, the influence of cardiovascular risk factors, inflammation, endothelial dysfunction. With objective to perform a systematic review of the studies which evaluate retinal vessels in ageing, we conducted the search of published reports (2003-2020). The review provided the evidence of narrowing of the caliber of retinal arterioles and venules in ageing; inverse relationship has been found in ethnically heterogeneous populations in a wide age range from 4th to 9th decade. The age dynamics of arteriovenous ratio (AVR) is evaluated less consistently. The available data showed the loss of complexity of the retinal microcirculatory bloodstream in elderly age, which might lead to a decrease in functional activity of microcirculation; however the studies are limited for systematic conclusions. The large population studies in Russia on this topic are practically absent. The researches of the microvascular retinal bloodstream in aging using the automatic analysis of the modern range of indicators, are relevant in the Russian population and will provide new data.

Injury measurements improve interpretation of thrombus formation data in the cremaster arteriole laser-induced injury model of thrombosis

Background

The cremaster arteriole laser-induced injury model is a powerful technique with which to investigate the molecular mechanisms that drive thrombus formation. This model is capable of direct visualization and quantification of accumulation of thrombus constituents, including both platelets and fibrin. However, a large degree of variability in platelet accumulation and fibrin formation is observed between thrombi. Strategies to understand this variability will enhance performance and standardization of the model. We determined whether ablation injury size contributes to variation in platelet accumulation and fibrin formation and, if so, whether incorporating ablation injury size into measurements reduces variation.

Methods

Thrombus formation was initiated by laser-induced injury of cremaster arterioles of mice (n=59 injuries). Ablation injuries within the vessel wall were consistently identified and quantified by measuring the length of vessel wall injury observed immediately following laser-induced disruption. Platelet accumulation and fibrin formation as detected by fluorescently-labeled antibodies were captured by digital intra-vital microscopy.

Results

Laser-induced disruption of the vessel wall resulted in ablation injuries of variable length (18-95 μm) enabling interrogation of the relationship between injury severity and thrombus dynamics. Strong positive correlations were observed between vessel injury length and both platelet and fibrin when the data are transformed as area under the curve (Spearman r = 0.80 and 0.76 respectively). Normalization of area under the curve measurements by injury length reduced intraclass coefficients of variation among thrombi and improved hypothesis testing when comparing different data sets.

Conclusions

Measurement of vessel wall injury length provides a reliable and robust marker of injury severity. Injury length can effectively normalize measurements of platelet accumulation and fibrin formation improving data interpretation and standardization.

The Effects of Surgical Treatment on Retina-Choroidal Findings in Patients With Obstructive Sleep Apnea Syndrome

BACKGROUND AND OBJECTIVE

The purpose of this study was to determine the effect of surgical treatment on ocular findings in obstructive sleep apnea syndrome (OSAS).

PATIENTS AND METHODS

The authors studied 34 eyes of 34 newly diagnosed OSAS patients. The sleep study was performed before and 6 months after expansion sphincter pharyngoplasty (ESP). Retinal nerve fiber layer (RNFL), choroidal thickness (CT), and retinal arteriolar caliber (RAC) analyses were performed using spectral-domain optical coherence tomography. Intraocular pressure (IOP) and ocular pulse amplitude were performed using the Pascal dynamic contour tonometer.

RESULTS

The preoperative and postoperative Apnea Hypopnea Index scores and average oxygen saturation values were significantly different (P = .0001 and P = .001, respectively). There was no significant difference between the preoperative and postoperative RNFL thicknesses (P > .05). The preoperative subfoveal, nasal, temporal CT, and IOP were significantly different from the postoperative measurements (P = .006, P = .05, P = .036, and P = .0001, respectively).

CONCLUSIONS

ESP had a significant influence on CT and IOP in patients with OSAS, maintaining a decrease in CT and IOP 6 months after surgery. The determination of these ocular findings may be useful to show the positive effects of ESP. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:35-42.].