Specific and Nonuniform Brain States during Cold Perception in Mice.

The quest to decode the complex supraspinal mechanisms that integrate cutaneous thermal information in the central system is still ongoing. The dorsal horn of the spinal cord is the first hub that encodes thermal input which is then transmitted to brain regions via the spinothalamic and thalamocortical pathways. So far, our knowledge about the strength of the interplay between the brain regions during thermal processing is limited. To address this question, we imaged the brains of adult awake male mice in resting state using functional ultrasound imaging during plantar exposure to constant and varying temperatures. Our study reveals for the first time the following: (1) a dichotomy in the response of the somatomotor-cingulate cortices and the hypothalamus, which was never described before, due to the lack of appropriate tools to study such regions with both good spatial and temporal resolutions. (2) We infer that cingulate areas may be involved in the affective responses to temperature changes. (3) Colder temperatures (ramped down) reinforce the disconnection between the somatomotor-cingulate and hypothalamus networks. (4) Finally, we also confirm the existence in the mouse brain of a brain mode characterized by low cognitive strength present more frequently at resting neutral temperature. The present study points toward the existence of a common hub between somatomotor and cingulate regions, whereas hypothalamus functions are related to a secondary network.

Individual Patient Data Meta-Analysis of Dynamic Cerebral Autoregulation and Functional Outcome After Ischemic Stroke.

BACKGROUND: The relationship between dynamic cerebral autoregulation (dCA) and functional outcome after acute ischemic stroke (AIS) is unclear. Previous studies are limited by small sample sizes and heterogeneity. METHODS: We performed a 1-stage individual patient data meta-analysis to investigate associations between dCA and functional outcome after AIS. Participating centers were identified through a systematic search of the literature and direct invitation. We included centers with dCA data within 1 year of AIS in adults aged over 18 years, excluding intracerebral or subarachnoid hemorrhage. Data were obtained on phase, gain, coherence, and autoregulation index derived from transfer function analysis at low-frequency and very low-frequency bands. Cerebral blood velocity, arterial pressure, end-tidal carbon dioxide, heart rate, stroke severity and sub-type, and comorbidities were collected where available. Data were grouped into 4 time points after AIS: <24 hours, 24 to 72 hours, 4 to 7 days, and >3 months. The modified Rankin Scale assessed functional outcome at 3 months. Modified Rankin Scale was analyzed as both dichotomized (0 to 2 versus 3 to 6) and ordinal (modified Rankin Scale scores, 0-6) outcomes. Univariable and multivariable analyses were conducted to identify significant relationships between dCA parameters, comorbidities, and outcomes, for each time point using generalized linear (dichotomized outcome), or cumulative link (ordinal outcome) mixed models. The participating center was modeled as a random intercept to generate odds ratios with 95% CIs. RESULTS: The sample included 384 individuals (35% women) from 7 centers, aged 66.3±13.7 years, with predominantly nonlacunar stroke (n=348, 69%). In the affected hemisphere, higher phase at very low-frequency predicted better outcome (dichotomized modified Rankin Scale) at <24 (crude odds ratios, 2.17 [95% CI, 1.47-3.19]; P<0.001) hours, 24-72 (crude odds ratios, 1.95 [95% CI, 1.21-3.13]; P=0.006) hours, and phase at low-frequency predicted outcome at 3 (crude odds ratios, 3.03 [95% CI, 1.10-8.33]; P=0.032) months. These results remained after covariate adjustment. CONCLUSIONS: Greater transfer function analysis-derived phase was associated with improved functional outcome at 3 months after AIS. dCA parameters in the early phase of AIS may help to predict functional outcome.

Noninvasive microvascular imaging in newborn rats using high-frequency ultrafast ultrasound.

Ultrasound imaging stands as the predominant modality for neonatal health assessment, with recent advancements in ultrafast Doppler (µDoppler) technology offering significant promise in fields such as neonatal brain imaging. Combining µDoppler with high-frequency ultrasound (HF-µDoppler) presents a potential efficient avenue to enhance in vivo microvascular imaging in small animals, notably newborn rats, a crucial preclinical animal model for neonatal disease and development research. It is necessary to verify the imaging performance of HF-µDoppler in preclinical trials. This study investigates the microvascular imaging capabilities of HF-µDoppler using a 30 MHz high-frequency linear array probe in newborn rats. Results demonstrate the clarity of cerebral microvascular imaging in rats aged 1 to 7 postnatal days, extending to whole-body microvascular imaging, encompassing the central nervous system, including the brain and spinal cord. In conclusion, HF-µDoppler technology emerges as a reliable imaging tool, offering a new perspective for preclinical investigations into neonatal diseases and development.

Displacement and functional ultrasound (fUS) imaging of displacement-guided focused ultrasound (FUS) neuromodulation in mice.

Focused ultrasound (FUS) stimulation is a promising neuromodulation technique with the merits of non-invasiveness, high spatial resolution, and deep penetration depth. However, simultaneous imaging of FUS-induced brain tissue displacement and the subsequent effect of FUS stimulation on brain hemodynamics has proven challenging thus far. In addition, earlier studies lack in situ confirmation of targeting except for the magnetic resonance imaging-guided FUS system-based studies. The purpose of this study is 1) to introduce a fully ultrasonic approach to in situ target, modulate neuronal activity, and monitor the resultant neuromodulation effect by respectively leveraging displacement imaging, FUS, and functional ultrasound (fUS) imaging, and 2) to investigate FUS-evoked cerebral blood volume (CBV) response and the relationship between CBV and displacement. We performed displacement imaging on craniotomized mice to confirm the in situ targeting for neuromodulation site. We recorded hemodynamic responses evoked by FUS while fUS imaging revealed an ipsilateral CBV increase that peaks at 4 s post-FUS. We report a stronger hemodynamic activation in the subcortical region than cortical, showing good agreement with a brain elasticity map that can also be obtained using a similar methodology. We observed dose-dependent CBV responses with peak CBV, activated area, and correlation coefficient increasing with the ultrasonic dose. Furthermore, by mapping displacement and hemodynamic activation, we found that displacement colocalized and linearly correlated with CBV increase. The findings presented herein demonstrated that FUS evokes ipsilateral hemodynamic activation in cortical and subcortical depths while the evoked hemodynamic responses colocalize and correlate with FUS-induced displacement. We anticipate that our findings will help consolidate accurate targeting as well as shedding light on one of the mechanisms behind FUS modulation, i.e., how FUS mechanically displaces brain tissue affecting cerebral hemodynamics and thereby its associated connectivity.

Recent developments in tornado theory and observations.

This article critically reviews research on tornado theory and observations over the last decade. From the theoretical standpoint, the major advances have come through improved numerical-simulation models of supercell convective storms, the tornado's parent circulation. These simulations are carried out on a large domain (to capture the supercell's circulation system), but with high grid resolution and improved representations of sub-grid physics (to capture the tornado). These simulations offer new insights into how and why tornadoes form in some supercells, but not others. Observational advances have come through technological improvements of mobile Doppler radars capable of rapid scanning and dual-polarization measurements, which offer a much more accurate view of tornado formation, tornado structure, and the tornado's place within its parent supercell.

Coherent light scattering from cellular dynamics in living tissues.

This review examines the biological physics of intracellular transport probed by the coherent optics of dynamic light scattering from optically thick living tissues. Cells and their constituents are in constant motion, composed of a broad range of speeds spanning many orders of magnitude that reflect the wide array of functions and mechanisms that maintain cellular health. From the organelle scale of tens of nanometers and upward in size, the motion inside living tissue is actively driven rather than thermal, propelled by the hydrolysis of bioenergetic molecules and the forces of molecular motors. Active transport can mimic the random walks of thermal Brownian motion, but mean-squared displacements are far from thermal equilibrium and can display anomalous diffusion through Lévy or fractional Brownian walks. Despite the average isotropic three-dimensional environment of cells and tissues, active cellular or intracellular transport of single light-scattering objects is often pseudo-one-dimensional, for instance as organelle displacement persists along cytoskeletal tracks or as membranes displace along the normal to cell surfaces, albeit isotropically oriented in three dimensions. Coherent light scattering is a natural tool to characterize such tissue dynamics because persistent directed transport induces Doppler shifts in the scattered light. The many frequency-shifted partial waves from the complex and dynamic media interfere to produce dynamic speckle that reveals tissue-scale processes through speckle contrast imaging and fluctuation spectroscopy. Low-coherence interferometry, dynamic optical coherence tomography, diffusing-wave spectroscopy, diffuse-correlation spectroscopy, differential dynamic microscopy and digital holography offer coherent detection methods that shed light on intracellular processes. In health-care applications, altered states of cellular health and disease display altered cellular motions that imprint on the statistical fluctuations of the scattered light. For instance, the efficacy of medical therapeutics can be monitored by measuring the changes they induce in the Doppler spectra of livingex vivocancer biopsies.

Biventricular responses to exercise and their relation to cardiorespiratory fitness in pediatric pulmonary hypertension.

Despite exercise intolerance being predictive of outcomes in pulmonary arterial hypertension (PAH), its underlying cardiac mechanisms are not well described. The aim of the study was to explore the biventricular response to exercise and its associations with cardiorespiratory fitness in children with PAH. Participants underwent incremental cardiopulmonary exercise testing and simultaneous exercise echocardiography on a recumbent cycle ergometer. Linear mixed models were used to assess cardiac function variance and associations between cardiac and metabolic parameters during exercise. Eleven participants were included with a mean age of 13.4 ± 2.9 yr old. Right ventricle (RV) systolic pressure (RVsp) increased from a mean of 59 ± 25 mmHg at rest to 130 ± 40 mmHg at peak exercise (P < 0.001), whereas RV fractional area change (RV-FAC) and RV-free wall longitudinal strain (RVFW-Sl) worsened (35.2 vs. 27%, P = 0.09 and -16.6 vs. -14.6%, P = 0.1, respectively). At low- and moderate-intensity exercise, RVsp was positively associated with stroke volume and O2 pulse (P < 0.1). At high-intensity exercise, RV-FAC, RVFW-Sl, and left ventricular longitudinal strain were positively associated with oxygen uptake and O2 pulse (P < 0.1), whereas stroke volume decreased toward peak (P = 0.04). In children with PAH, the increase of pulmonary pressure alone does not limit peak exercise, but rather the concomitant reduced RV functional reserve, resulting in RV to pulmonary artery (RV-PA) uncoupling, worsening of interventricular interaction and LV dysfunction. A better mechanistic understanding of PAH exercise physiopathology can inform stress testing and cardiac rehabilitation in this population.NEW & NOTEWORTHY In children with pulmonary arterial hypertension, there is a marked increase in pulmonary artery pressure during physical activity, but this is not the underlying mechanism that limits exercise. Instead, right ventricle-to-pulmonary artery uncoupling occurs at the transition from moderate to high-intensity exercise and correlates with lower peak oxygen uptake. This highlights the more complex underlying pathological responses and the need for multiparametric assessment of cardiac function reserve in these patients when feasible.

Evaluating transient phenomena by wavelet analysis: early recovery to exercise.

Wavelet analysis (WA) provides superior time-frequency decomposition of complex signals than conventional spectral analysis tools. To illustrate its usefulness in assessing transient phenomena, we applied a custom-developed WA algorithm to laser-Doppler (LD) signals of the cutaneous microcirculation measured at glabrous (finger pulp) and nonglabrous (forearm) sites during early recovery after dynamic exercise. This phase, importantly contributing to the establishment of thermal homeostasis after exercise cessation, has not been adequately explored because of its complex, transient form. Using WA, we decomposed the LD signals measured during the baseline and early recovery into power spectra of characteristic frequency intervals corresponding to endothelial nitric oxide (NO)-dependent, neurogenic, myogenic, respiratory, and cardiac physiological influence. Assessment of relative power (RP), defined as the ratio between the median power in the frequency interval and the median power of the total spectrum, revealed that endothelial NO-dependent (5.87 early recovery; 1.53 baseline; P = 0.005; Wilcoxon signed-rank test) and respiratory (0.71 early recovery; 0.40 baseline; P = 0.001) components were significantly increased, and myogenic component (1.35 early recovery; 1.83 baseline; P = 0.02) significantly decreased during early recovery in the finger pulp. In the forearm, only the RP of the endothelial NO-dependent (1.90 early recovery; 0.94 baseline; P = 0.009) component was significantly increased. WA presents an irreplaceable tool for the assessment of transient phenomena. The relative contribution of the physiological mechanisms controlling the microcirculatory response in the early recovery phase appears to differ in glabrous and nonglabrous skin when compared with baseline; moreover, the endothelial NO-dependent influence seems to play an important role.NEW & NOTEWORTHY We address the applicability of wavelet analysis (WA) in evaluating transient phenomena on a model of early recovery to exercise, which is the only exercise-associated phase characterized by a distinct transient shape and as such cannot be assessed using conventional tools. Our WA-based algorithm provided a reliable spectral decomposition of laser-Doppler (LD) signals in early recovery, enabling us to speculate roughly on the mechanisms involved in the regulation of skin microcirculation in this phase.

Cerebral Microcirculation: Progress and Outlook of Laser Doppler Flowmetry in Neurosurgery and Neurointensive Care.

Laser Doppler flowmetry (LDF) is a well-established technique for the investigation of tissue microcirculation. Compared to skin, the use in the human brain is sparse. The measurement of cerebral microcirculation in neurointensive care and during neurosurgery is challenging and requires adaptation to the respective clinical setting. The aim of the review is to present state of the art and progress in neurosurgery and neurointensive care where LDF has proven useful and can find clinical importance in the investigation of cerebral microcirculation. The literature in the field is summarized and recent technical improvements regarding LDF systems and fiber optical probe designs for neurosurgical and neurocritical care described. By combining two signals from the LDF unit, the measurement of the microcirculation (Perfusion) and gray whiteness (TLI) of the brain tissue, the full potential of the device is achieved. For example, a forward-looking LDF-probe detects high-risk hemorrhage areas and gray-white matter boundaries along intraoperative trajectories during stereotactic neurosurgery. Proof of principles are given for LDF as a guidance tool in deep brain stimulation implantation, brain tumor needle biopsies, and as long-term monitoring device in neurocritical care. With well-designed fiber optical probes, surgical fixation, and signal processing for movement reduction, LDF monitoring of the cerebral microcirculation is successful up to 10 days. The use of LDF can be combined with other physiological measurement techniques, for example, fluorescence spectroscopy for identification of glioblastoma during tumor surgery. Fiber optics can also be used during magnetic resonance imaging (MRI). Despite the many advantages, fiber optical LDF has not yet reached its full potential in clinical neuro-applications. Multicenter studies are required to further evaluate LDF in neurosurgery and neurointensive care. In conclusion, the present status of LDF in neurosurgery and neurointensive care has been reviewed. By combining Perfusion and TLI with tailored probe designs the full potential of LDF can be achived in measuring cerebral microcirculation. This includes guidance during DBS implantation and needle biopsies, and long-term monitoring in neurocritical care.

Dynamic Microcirculation Characteristics of Plantar Skin Under Metatarsal Head of Human Foot in Response to Life-Like Pressure Stimulus.

OBJECTIVE: Diabetic foot ulcer (DFU) is a severe complication with high mortality. High plantar pressure and poor microcirculation are considered main causes of DFU. The specific aims were to provide a novel technique for real-time measurement of plantar skin blood flow (SBF) under walking-like pressure stimulus and delineate the first plantar metatarsal head dynamic microcirculation characteristics because of life-like loading conditions in healthy individuals. METHODS: Twenty young healthy participants (14 male and 6 female) were recruited. The baseline (i.e., unloaded) SBF of soft tissue under the first metatarsal head were measured using laser Doppler flowmetry (LDF). A custom-made machine was utilized to replicate daily walking pressure exertion for 5 min. The exerted plantar force was adjusted from 10 N (127.3 kPa) to 40 N (509.3 kPa) at an increase of 5 N (63.7 kPa). Real-time SBF was acquired using the LDF. After each pressure exertion, postload SBF was measured for comparative purposes. Statistical analysis was performed using the R software. RESULTS: All levels of immediate-load and postload SBF increased significantly compared with baseline values. As the exerted load increased, the postload and immediate-load SBF tended to increase until the exerted load reached 35 N (445.6 kPa). However, in immediate-load data, the increasing trend tended to level off as the exerted pressure increased from 15 N (191.0 kPa) to 25 N (318.3 kPa). For postload and immediate-load SBF, they both peaked at 35 N (445.6 kPa). However, when the exerted force exceeds 35 N (445.6 kPa), both the immediate-load and postload SBF values started to decrease. CONCLUSIONS: Our study offered a novel real-time plantar soft tissue microcirculation measurement technique under dynamic conditions. For the first metatarsal head of healthy people, 20 N (254.6 kPa)-plantar pressure has a fair microcirculation stimulus compared with higher pressure. There might be a pressure threshold at 35 N (445.6 kPa) for the first metatarsal head, and soft tissue microcirculation may decrease when local pressure exceeds it.

Lycium barbarum glycopeptide promotes neuroprotection in ET-1 mediated retinal ganglion cell degeneration.

BACKGROUND: Vascular dysregulation is one of the major risk factors of glaucoma, and endothelin-1 (ET-1) may have a role in the pathogenesis of vascular-related glaucoma. Fruit extract from Lycium Barbarum (LB) exhibits anti-ageing and multitarget mechanisms in protecting retinal ganglion cells (RGC) in various animal models. To investigate the therapeutic efficacy of LB glycoproteins (LbGP) in ET-1 induced RGC degeneration, LbGP was applied under pre- and posttreatment conditions to an ET-1 mouse model. Retina structural and functional outcomes were characterised using clinical-based techniques. METHODS: Adult C57BL/6 mice were randomly allocated into four experimental groups, namely vehicle control (n = 9), LbGP-Pretreatment (n = 8), LbGP-Posttreatment (day 1) (n = 8) and LbGP-Posttreatment (day 5) (n = 7). Oral administration of LbGP 1 mg/Kg or PBS for vehicle control was given once daily. Pre- and posttreatment (day 1 or 5) were commenced at 1 week before and 1 or 5 days after intravitreal injections, respectively, and were continued until postinjection day 28. Effects of treatment on retinal structure and functions were evaluated using optical coherence tomography (OCT), doppler OCT and electroretinogram measurements at baseline, post-injection days 10 and 28. RGC survival was evaluated by using RBPMS immunostaining on retinal wholemounts. RESULTS: ET-1 injection in vehicle control induced transient reductions in arterial flow and retinal functions, leading to significant RNFL thinning and RGC loss at day 28. Although ET-1 induced a transient loss in blood flow or retinal functions in all LbGP groups, LbGP treatments facilitated better restoration of retinal flow and retinal functions as compared with the vehicle control. Also, all three LbGP treatment groups (i.e. pre- and posttreatments from days 1 or 5) significantly preserved thRNFL thickness and RGC densities. No significant difference in protective effects was observed among the three LbGP treatment groups. CONCLUSION: LbGP demonstrated neuroprotective effects in a mouse model of ET-1 induced RGC degeneration, with treatment applied either as a pretreatment, immediate or delayed posttreatment. LbGP treatment promoted a better restoration of retinal blood flow, and protected the RNFL, RGC density and retinal functions. This study showed the translational potential of LB as complementary treatment for glaucoma management.

Shape of Pulmonary Artery Doppler Flow Profile and Right Ventricular Hemodynamics in Neonates.

OBJECTIVES: To characterize pulmonary artery Doppler flow profile (PAFP) patterns among infants receiving care in neonatal intensive care units and to examine the association of PAFP patterns with pulmonary and right ventricular (RV) hemodynamics. STUDY DESIGN: This is a retrospective study at 2 tertiary intensive care units over 4 years that included neonates who demonstrated a complete tricuspid regurgitation envelope on targeted neonatal echocardiography. Separate personnel reviewed TNEs to characterize PAFP patterns, divide cohort into PAFP groups, and measure quantitative indices of RV hemodynamics (RV systolic pressure, pulmonary artery acceleration time and its ratio with RV ejection time, tricuspid annular plane systolic excursion, and RV output), for intergroup comparisons. RESULTS: We evaluated TNEs from 186 neonates with median gestational age of 28.5 weeks (IQR, 25.9-35.9 weeks). Four distinct PAFP patterns were identified (A) near-isosceles triangle (22%), (B) right-angled triangle (29%), (C) notching (40%), and (D) low peak velocity (<0.4 m/s; 9%). Groups A-C demonstrated a stepwise worsening in all indices of PH, whereas pattern D was associated with lower tricuspid annular plane systolic excursion and RV output. Using common definitions of pulmonary hypertension (PH), pattern A performed best to rule out PH (sensitivity range, 81%-90%) and pattern C for diagnosing PH (specificity range, 63%-78%). CONCLUSIONS: Inspection of PAFP is a simple bedside echocardiography measure that provides clinically meaningful information on underlying RV hemodynamics and may aid in screening and monitoring of patients for PH in intensive care units.

The longitudinal study of muscle changes with ultrasound: differential changes in idiopathic inflammatory myopathy subgroups.

OBJECTIVES: We investigated shear wave elastography (SWE), B mode US and power Doppler (PDUS) as imaging biomarkers for longitudinal follow-up in idiopathic inflammatory myopathy (IIM), with a particular focus on immune-mediated necrotizing myopathy (IMNM) and DM. METHODS: Participants had serial SWE, PDUS on the deltoid (D) and vastus lateralis (VL) muscles on four occasions at intervals of 3-6 months. Clinical assessments included manual muscle testing, and patient- and physician-reported outcome scales. RESULTS: Thirty-three participants were included: IMNM = 17, DM = 12, overlap myositis = 3, PM = 1. Twenty were in a prevalent clinic group, and 13 were recently treated cases in an incident group. Differential changes in SWS and US domains occurred with time in both the prevalent and incident groups. In the VL-prevalent subgroup, echogenicity increased over time (P = 0.040), while in the incident cases there was a trend for reduction to normal over time (P = 0.097) with treatment. Muscle bulk reduced in the D-prevalent subgroup over time (P = 0.096), suggesting atrophy. SWS also reduced in the VL-incident subgroup over time (P = 0.096), suggesting a trend towards improvement in muscle stiffness with treatment. CONCLUSION: SWE and US appear promising as imaging biomarkers for patient follow-up in IIM and indicate changes over time, especially with echogenicity, muscle bulk and SWS in the VL. Due to the limitations of the participant numbers, additional studies with a larger cohort are needed to help evaluate these US domains further and outline specific characteristics within the IIM subgroups.

Diagnostic accuracy of the maximal systolic acceleration to detect peripheral arterial disease.

BACKGROUND: Diagnosing peripheral arterial disease (PAD) can be challenging owing to medial arterial calcification (MAC) in patients with diabetes mellitus (DM) and chronic kidney disease (CKD). Current bedside tests, such as the ankle-brachial index and toe-brachial index, are often insufficient. The maximal systolic acceleration (ACCmax) is a velocimetric Doppler-derived parameter and could be a new promising test in the diagnostic workup of these patients. The primary aim of this study was to evaluate the diagnostic performance of the ACCmax to detect PAD. METHODS: A retrospective cohort study was performed in a tertiary referral hospital. Patients ≥18 years old with suspected PAD who underwent ACCmax measurement(s) along with computed tomography angiography of the abdominal aorta and lower extremities (reference test) were eligible for inclusion. ACCmax measurements of the posterior tibial artery, anterior tibial artery and peroneal artery were collected. Diagnostic performance was assessed by using sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and area under the curve (AUC). RESULTS: In total, 340 patients (618 limbs) were included. Approximately 40% suffered from DM and 30% had CKD. Diagnostic performance of the ACCmax to detect PAD for the posterior tibial artery showed a sensitivity of 90%, specificity of 93%, positive likelihood ratio of 12.83, and negative likelihood ratio of 0.11 (AUC, 0.953). For the anterior tibial artery, these results were 94%, 97%, 32.06, and 0.06 (same sequence as presented before) with an AUC of 0.984. The peroneal artery had a performance of 86%, 89%, 7.51, and 0.16, respectively (AUC, 0.893). Diagnostic accuracy of the ACCmax did not diminish in subgroup analysis for patients with DM or CKD. CONCLUSIONS: The ACCmax showed excellent diagnostic performance to detect PAD, independent of patients prone to medial arterial calcification.

Artificial intelligence of arterial Doppler waveforms to predict major adverse outcomes among patients with diabetes mellitus.

OBJECTIVE: Patients with diabetes mellitus (DM) are at increased risk for peripheral artery disease (PAD) and its complications. Arterial calcification and non-compressibility may limit test interpretation in this population. Developing tools capable of identifying PAD and predicting major adverse cardiac event (MACE) and limb event (MALE) outcomes among patients with DM would be clinically useful. Deep neural network analysis of resting Doppler arterial waveforms was used to detect PAD among patients with DM and to identify those at greatest risk for major adverse outcome events. METHODS: Consecutive patients with DM undergoing lower limb arterial testing (April 1, 2015-December 30, 2020) were randomly allocated to training, validation, and testing subsets (60%, 20%, and 20%). Deep neural networks were trained on resting posterior tibial arterial Doppler waveforms to predict all-cause mortality, MACE, and MALE at 5 years using quartiles based on the distribution of the prediction score. RESULTS: Among 11,384 total patients, 4211 patients with DM met study criteria (mean age, 68.6 ± 11.9 years; 32.0% female). After allocating the training and validation subsets, the final test subset included 856 patients. During follow-up, there were 262 deaths, 319 MACE, and 99 MALE. Patients in the upper quartile of prediction based on deep neural network analysis of the posterior tibial artery waveform provided independent prediction of death (hazard ratio [HR], 3.58; 95% confidence interval [CI], 2.31-5.56), MACE (HR, 2.06; 95% CI, 1.49-2.91), and MALE (HR, 13.50; 95% CI, 5.83-31.27). CONCLUSIONS: An artificial intelligence enabled analysis of a resting Doppler arterial waveform permits identification of major adverse outcomes including all-cause mortality, MACE, and MALE among patients with DM.

Morphologic development of the first-trimester utero-placental vasculature is positively associated with embryonic and fetal growth: the Rotterdam Periconception Cohort.

STUDY QUESTION: Is morphologic development of the first-trimester utero-placental vasculature associated with embryonic growth and development, fetal growth, and birth weight percentiles? SUMMARY ANSWER: Using the utero-placental vascular skeleton (uPVS) as a new imaging marker, this study reveals morphologic development of the first-trimester utero-placental vasculature is positively associated with embryonic growth and development, fetal growth, and birth weight percentiles. WHAT IS KNOWN ALREADY: First-trimester development of the utero-placental vasculature is associated with placental function, which subsequently impacts embryonic and fetal ability to reach their full growth potential. The attribution of morphologic variations in the utero-placental vascular development, including the vascular structure and branching density, on prenatal growth remains unknown. STUDY DESIGN, SIZE, DURATION: This study was conducted in the VIRTUAL Placental study, a subcohort of 214 ongoing pregnancies, embedded in the prospective observational Rotterdam Periconception Cohort (Predict study). Women were included before 10 weeks gestational age (GA) at a tertiary referral hospital in The Netherlands between January 2017 and March 2018. PARTICIPANTS/MATERIALS, SETTING, METHODS: We obtained three-dimensional power Doppler volumes of the gestational sac including the embryo and the placenta at 7, 9, and 11 weeks of gestation. Virtual Reality-based segmentation and a recently developed skeletonization algorithm were applied to the power Doppler volumes to generate the uPVS and to measure utero-placental vascular volume (uPVV). Absolute vascular morphology was quantified by assigning a morphologic characteristic to each voxel in the uPVS (i.e. end-, bifurcation-crossing-, or vessel point). Additionally, total vascular length (mm) was calculated. The ratios of the uPVS characteristics to the uPVV were calculated to determine the density of vascular branching. Embryonic growth was estimated by crown-rump length and embryonic volume. Embryonic development was estimated by Carnegie stages. Fetal growth was measured by estimated fetal weight in the second and third trimester and birth weight percentiles. Linear mixed models were used to estimate trajectories of longitudinal measurements. Linear regression analysis with adjustments for confounders was used to evaluate associations between trajectories of the uPVS and prenatal growth. Groups were stratified for conception method (natural/IVF-ICSI conceptions), fetal sex (male/female), and the occurrence of placenta-related complications (yes/no). MAIN RESULTS AND THE ROLE OF CHANCE: Increased absolute vascular morphologic development, estimated by positive random intercepts of the uPVS characteristics, is associated with increased embryonic growth, reflected by crown-rump length (endpoints ß = 0.017, 95% CI [0.009; 0.025], bifurcation points ß = 0.012, 95% CI [0.006; 0.018], crossing points ß = 0.017, 95% CI [0.008; 0.025], vessel points ß = 0.01, 95% CI [0.002; 0.008], and total vascular length ß = 0.007, 95% CI [0.003; 0.010], and similarly with embryonic volume and Carnegie stage, all P-values ≤ 0.01. Density of vascular branching was negatively associated with estimated fetal weight in the third trimester (endpoints: uPVV ß = -94.972, 95% CI [-185.245; -3.698], bifurcation points: uPVV ß = -192.601 95% CI [-360.532; -24.670]) and birth weight percentiles (endpoints: uPVV ß = -20.727, 95% CI [-32.771; -8.683], bifurcation points: uPVV ß -51.097 95% CI [-72.257; -29.937], and crossing points: uPVV ß = -48.604 95% CI [-74.246; -22.961])), all P-values < 0.05. After stratification, the associations were observed in natural conceptions specifically. LIMITATION, REASONS FOR CAUTION: Although the results of this prospective observational study clearly demonstrate associations between first-trimester utero-placental vascular morphologic development and prenatal growth, further research is required before we can draw firm conclusions about a causal relationship. WIDER IMPLICATIONS OF THE FINDINGS: Our findings support the hypothesis that morphologic variations in utero-placental vascular development play a role in the vascular mechanisms involved in embryonic and fetal growth and development. Application of the uPVS could benefit our understanding of the pathophysiology underlying placenta-related complications. Future research should focus on the clinical applicability of the uPVS as an imaging marker for the early detection of fetal growth restriction. STUDY FUNDING/COMPETING INTEREST(S): This research was funded by the Department of Obstetrics and Gynecology of the Erasmus MC, University Medical Centre, Rotterdam, The Netherlands. There are no conflicts of interest. TRIAL REGISTRATION NUMBER: Registered at the Dutch Trial Register (NTR6854).

Robust analysis of microcirculatory flowmotion during post-occlusive reactive hyperemia.

BACKGROUND: Flowmotion analysis of the microcirculatory blood flow is a method to extract information about the vessel regulatory function. It has previously shown promise when applied to measurements during a post-occlusive reactive hyperemia. However, the reperfusion peak and the following monotonic decline introduces false low frequencies that should not be interpreted as rhythmic vasomotion effect. AIM: To develop and validate a robust method for flowmotion analysis of post-occlusive reactive hyperemia signals. METHOD: The occlusion-induced reperfusion response contains a typical rapid increase followed by a monotonic decline to baseline. A mathematical model is proposed to detrend this transient part of the signal to enable further flowmotion analysis. The model is validated in 96 measurements on healthy volunteers. RESULTS: Applying the proposed model corrects the flowmotion signal without adding any substantial new false flowmotion components. CONCLUSION: Future studies should use the proposed method or equivalent when analyzing flowmotion during post-occlusive reactive hyperemia to ensure valid results.

Reproducibility of Laser Doppler Flowmetry in gingival microcirculation. A study on six different protocols.

OBJECTIVES: Laser Doppler Flowmetry (LDF) is a non-invasive technique for the assessment of tissue blood flow, but increased reproducibility would facilitate longitudinal studies. The aim of the study was to assess the interday reproducibility of Laser Doppler Flowmetry (LDF) at rest, at elevated local temperatures, and with the use of the vasodilator Methyl Nicotinate (MN) in six interconnected protocols for the measurement of the blood supply to the microvascular bed of the gingiva. METHODS: Ten healthy volunteers were included. Interweek LDF measurements with custom-made acrylic splints were performed. Six protocols were applied in separate regions of interest (ROI): 1; basal LDF, 2; LDF with thermoprobe 42 °C, 3; LDF with thermoprobe 45 °C, 4; LDF with thermoprobe 42 °C and MN, 5; LDF with thermoprobe 45 °C and MN and 6; LDF with MN. RESULTS: Intra-individual reproducibility was assessed by the within-subject coefficient of variation (wCV) and the intraclass correlation coefficient (ICC). Basal LDF measurements demonstrated high reproducibility with wCV 11.1 in 2 min and 10.3 in 5 min. ICC was 0.9 and 0.92. wCV after heat and MN was 4.9-10.3 and ICC 0.82-0.93. The topically applied MN yielded increased blood flow. CONCLUSION: This is the first study evaluating the reproducibility of basal LDF compared to single or multiple vasodilatory stimuli in gingiva. Multiple collector fibers probe and stabilizing acrylic splints are recommended. Vasodilatory stimulation showed a tendency toward higher reproducibility. Furthermore, MN yields vasodilation in gingiva.

Vasomotion heterogeneity and spectral characteristics in diabetic and hypertensive patients.

Vasomotion refers to the spontaneous oscillation of blood vessels within a frequency range of 0.01 to 1.6 Hz. Various disease states, including hypertension and diabetes, have been associated with alterations in vasomotion at the finger, indicating potential impairment of skin microcirculation. Due to the non-linear nature of human vasculature, the modification of vasomotion may vary across different locations for different diseases. In this study, Laser Doppler Flowmetry was used to measure blood flow motion at acupoints LU8, LU5, SP6, and PC3 among 49 participants with or without diabetes and/or hypertension. Fast Fourier Transformation was used to analyze noise type while Hilbert-Huang Transformation and wavelet analysis were applied to assess Signal Noise Ratio (SNR) results. Statistical analysis revealed that different acupoints exhibit distinct spectral characteristics of vasomotion not only among healthy individuals but also among patients with diabetes and/or hypertension. The results showed strong heterogeneity of vasomotion among blood vessels, indicating that the vasomotion measured at a certain point may not reflect the real status of microcirculation.

Changes in renal microcirculation in patients with nephrotic and nephritic syndrome: The role of resistive index.

BACKGROUND: Renal Resistive Index (RRI) is an important and non-invasive parameter of renal damage and it is associated with abnormal microcirculation or to a parenchymal injury. The aim of our study was to compare the RRI in a cohort of patients with renal diseases categorized in three groups: nephrotic syndrome (NS), acute nephritic syndrome (ANS) and patients with urinary abnormalities (UA). METHODS: Four hundred eighty-two patients with median age of 48 years (IQR 34-62) with indications for kidney disease were included in the study. Biochemical analyses, clinical assessment with detection of NS, ANS and UA and comorbidities were reported. Renal Doppler ultrasound with RRI was evaluated in all patients at the time of enrolment. RESULTS: NS was present in 81 (16.8 %) patients while ANS in 81 (16.8 %) and UA in 228 (47.3 %) patients. Patients with ANS showed significant higher RRI compared to both patients with NS [0.71 (IQR 0.67-0.78) vs 0.68 (0.63-0.73), p < 0.001] and UA [0.71 (0.67-0.78) vs 0.65 (0.61-0.71), p < 0.001]; RRI was higher in NS patients than in patients with UA [0.68 (0.63-0.73) vs 0.65 (0.61-0.71), p < 0.001]. Patients with ANS had significantly lower median estimated glomerular filtration rate (eGFR) compared respectively to NS and UA patients [19.7 ml/min vs 54.8 ml/min and vs 72.3 ml/min, p < 0.001], while renal length was significantly higher in patients with NS compared to both patients with ANS and UA [111.88 mm vs 101.98 mm and vs 106.15, p < 0.001]. Patients with ANS had more frequently hematuria and RRI ≥ 0.70 (p < 0.001) compared to both patients with NS and patients with UA. The multiple regression analysis, weighted for age, showed that RRI inversely correlates with eGFR (ß coefficient = -0.430, p < 0.001). CONCLUSIONS: Higher and pathological RRI were found in ANS than NS and UA. Renal resistive index in ANS reflects changes in intrarenal perfusion and microvascular dysfunction related to disease characteristics.