Selective neural inhibition via photobiomodulation alleviates behavioral hypersensitivity associated with small sensory fiber activation.

OBJECTIVE: Photobiomodulation at higher irradiances has great potential as a pain-alleviating method that selectively inhibits small diameter nerve fibers and corresponding sensory experiences, such as nociception and heat sensation. The longevity and magnitude of these effects as a function of laser irradiation parameters at the nerve was explored. METHODS: In a rodent chronic pain model (spared nerve injury-SNI), light was applied directly at the sural nerve with four delivery schemes: two irradiance levels (7.64 and 2.55 W/cm2 ) for two durations each, corresponding to either 4.8 or 14.4 J total energy, and the effect on sensory hypersensitivities was evaluated. RESULTS: At emitter irradiances of 7.64 W/cm2 (for 240 s), 2.55 W/cm2 (for 720 s), and 7.64 W/cm2 (for 80 s) the heat hypersensitivity was relieved the day following photobiomodulation (PBM) treatment by 37 ± 8.1% (statistically significant, p < 0.001), 26% ± 6% (p = 0.072), and 28 ± 6.1% (statistically significant, p = 0.032), respectively, and all three treatments reduced the hypersensitivity over the course of the experiment (13 days) at a statistically significant level (mixed-design analysis of variance, p < 0.05). The increases in tissue temperature (5.3 ± 1.0 and 1.3 ± 0.4°C from 33.3°C for the higher and lower power densities, respectively) at the neural target were well below those typically associated with permanent action potential disruption. CONCLUSIONS: The data from this study support the use of direct PBM on nerves of interest to reduce sensitivities associated with small-diameter fiber activity.

Direct Photobiomodulation Therapy on the Sciatic Nerve Significantly Attenuates Acute Nociceptive Sensitivity Without Affecting Motor Output.

OBJECTIVES: Pharmacologic pain treatments lack specific targeting and often produce unwanted side effects (eg, addiction, additional hyperalgesia). We previously established that the direct application of laser irradiation (direct photobiomodulation [PBM]) of the sural nerve reduces thermal hypersensitivity in a rodent model of chronic pain, but not mechanical hypersensitivity. These observations were consistent with a selective reduction in the small-diameter fiber contribution to electrophysiologically measured evoked response after direct PBM of a sensory nerve (saphenous). However, to our knowledge, direct application of laser irradiation has never been performed in an animal model of acute nociceptive pain or on a mixed nerve in which sensory and motor outcomes can be observed. MATERIALS AND METHODS: In this study, we describe the effects of direct application of laser irradiation (808 nm, 60 mW, 4 minutes) on a mixed nerve (sciatic nerve) in an acute nociceptive pain model (intradermal capsaicin injection) in rats over the course of two weeks. To investigate whether laser irradiation of a mixed nerve alters motor function, in separate experiments, we applied laser irradiation to the sciatic nerve (using the same parameters as in the chronic pain experiments), and force generation of the gastrocnemius was measured. RESULTS: Capsaicin-induced hypersensitivities to mechanical (pin prick) and thermal (Hargreaves) noxious stimuli, associated with Aδ- and C-fibers, showed a maximal reduction of 70% and 56.2%, respectively, by direct PBM, when compared with a control group (vehicle injection, no PBM) on the same day. This reduction was determined to be significant using a mixed-design analysis of variance with a p value < 0.05. Force generation remained unchanged for up to 120 minutes after laser irradiation. In summary, direct PBM selectively inhibits C- and Aδ-fiber transmission while leaving Aɑ-, Aß-, and motor-fiber activity intact. CONCLUSIONS: These results, in conjunction with our previous analyses of laser irradiation effects on the sural nerve in a chronic spared nerve injury pain model, suggest that direct PBM is a promising candidate for treating pain induced by small-diameter fiber activity.

Slide Over: Advances in Slide-Free Optical Microscopy as Drivers of Diagnostic Pathology.

Conventional analysis using clinical histopathology is based on bright-field microscopy of thinly sliced tissue specimens. Although bright-field microscopy is a simple and robust method of examining microscope slides, the preparation of the slides needed is a lengthy and labor-intensive process. Slide-free histopathology, however, uses direct imaging of intact, minimally processed tissue samples using advanced optical-imaging systems, bypassing the extended workflow now required for the preparation of tissue sections. This article explains the technical basis of slide-free microscopy, reviews common slide-free optical microscopy techniques, and discusses the opportunities and challenges involved in clinical implementation.

Selective Infrared Neural Inhibition Can Be Reproduced by Resistive Heating.

OBJECTIVES: Small-diameter afferent axons carry various sensory signals that are critical for vital physiological conditions but sometimes contribute to pathologies. Infrared (IR) neural inhibition (INI) can induce selective heat block of small-diameter axons, which holds potential for translational applications such as pain management. Previous research suggested that IR-heating-induced acceleration of voltage-gated potassium channel kinetics is the mechanism for INI. Therefore, we hypothesized that other heating methods, such as resistive heating (RH) in a cuff, could reproduce the selective inhibition observed in INI. MATERIALS AND METHODS: We conducted ex vivo nerve-heating experiments on pleural-abdominal connective nerves of Aplysia californica using both IR and RH. We fabricated a transparent silicone nerve cuff for simultaneous IR heating, RH, and temperature measurements. Temperature elevations (ΔT) on the nerve surface were recorded for both heating modalities, which were tested over a range of power levels that cover a similar ΔT range. We recorded electrically evoked compound action potentials (CAPs) and segmented them into fast and slow subcomponents on the basis of conduction velocity differences between the large and small-diameter axonal subpopulations. We calculated the normalized inhibition strength and inhibition selectivity index on the basis of the rectified area under the curve of each subpopulation. RESULTS: INI and RH showed a similar selective inhibition effect on CAP subcomponents for slow-conducting axons, confirmed by the inhibition probability vs ΔT dose-response curve based on approximately 2000 CAP measurements. The inhibition selectivity indexes of the two heating modalities were similar across six nerves. RH only required half the total electrical power required by INI to achieve a similar ΔT. SIGNIFICANCE: We show that selective INI can be reproduced by other heating modalities such as RH. RH, because of its high energy efficiency and simple design, can be a good candidate for future implantable neural interface designs.

Two single-axis scanners make a virtual gimbaled scanner.

A 2D scan generated from two single-axis scanning mirrors often has the beam steered about two distant axes that lead to scan artifacts, such as displacement jitters, telecentric errors, and spot variations. Previously, this problem has been addressed with complicated optical and mechanical designs, such as 4f relays and gimbaled mechanics, which ultimately limit the performance of the system. Here, we show that two single-axis scanners alone can produce a 2D scanning pattern nearly identical to a single-pivot gimbaled scanner through an apparently previously undiscovered simple geometry. This finding broadens the design parameter space of beam steering applications.

Prenatal ethanol exposure impairs the conduction delay at the atrioventricular junction in the looping heart.

The etiology of ethanol-related congenital heart defects has been the focus of much study, but most research has concentrated on cellular and molecular mechanisms. We have shown with optical coherence tomography (OCT) that ethanol exposure led to increased retrograde flow and smaller atrioventricular (AV) cushions compared with controls. Since AV cushions play a role in patterning the conduction delay at the atrioventricular junction (AVJ), this study aims to investigate whether ethanol exposure alters the AVJ conduction in early looping hearts and whether this alteration is related to the decreased cushion size. Quail embryos were exposed to a single dose of ethanol at gastrulation, and Hamburger-Hamilton stage 19-20 hearts were dissected for imaging. Cardiac conduction was measured using an optical mapping microscope and we imaged the endocardial cushions using OCT. Our results showed that, compared with controls, ethanol-exposed embryos exhibited abnormally fast AVJ conduction and reduced cushion size. However, this increased conduction velocity (CV) did not strictly correlate with decreased cushion volume and thickness. By matching the CV map to the cushion-size map along the inflow heart tube, we found that the slowest conduction location was consistently at the atrial side of the AVJ, which had the thinner cushions, not at the thickest cushion location at the ventricular side as expected. Our findings reveal regional differences in the AVJ myocardium even at this early stage in heart development. These findings reveal the early steps leading to the heterogeneity and complexity of conduction at the mature AVJ, a site where arrhythmias can be initiated.NEW & NOTEWORTHY To the best of our knowledge, this is the first study investigating the impact of ethanol exposure on the early cardiac conduction system. Our results showed that ethanol-exposed embryos exhibited abnormally fast atrioventricular conduction. In addition, our findings, in CV measurements and endocardial cushion thickness, reveal regional differences in the AVJ myocardium even at this early stage in heart development, suggesting that the differentiation and maturation at this site are complex and warrant further studies.

Glutathione Protects the Developing Heart from Defects and Global DNA Hypomethylation Induced by Prenatal Alcohol Exposure.

BACKGROUND: Fetal alcohol spectrum disorder (FASD) is caused by prenatal alcohol exposure (PAE), the intake of ethanol (C2 H5 OH) during pregnancy. Features of FASD cover a range of structural and functional defects including congenital heart defects (CHDs). Folic acid and choline, contributors of methyl groups to one-carbon metabolism (OCM), prevent CHDs in humans. Using our avian model of FASD, we have previously reported that betaine, another methyl donor downstream of choline, prevents CHDs. The CHD preventions are substantial but incomplete. Ethanol causes oxidative stress as well as depleting methyl groups for OCM to support DNA methylation and other epigenetic alterations. To identify more compounds that can safely and effectively prevent CHDs and other effects of PAE, we tested glutathione (GSH), a compound that regulates OCM and is known as a "master antioxidant." METHODS/RESULTS: Quail embryos injected with a single dose of ethanol at gastrulation exhibited congenital defects including CHDs similar to those identified in FASD individuals. GSH injected simultaneously with ethanol not only prevented CHDs, but also improved survival and prevented other PAE-induced defects. Assays of hearts at 8 days (HH stage 34) of quail development, when the heart normally has developed 4-chambers, showed that this single dose of PAE reduced global DNA methylation. GSH supplementation concurrent with PAE normalized global DNA methylation levels. The same assays performed on quail hearts at 3 days (HH stage 19-20) of development, showed no difference in global DNA methylation between controls, ethanol-treated, GSH alone, and GSH plus ethanol-treated cohorts. CONCLUSIONS: GSH supplementation shows promise to inhibit effects of PAE by improving survival, reducing the incidence of morphological defects including CHDs, and preventing global hypomethylation of DNA in heart tissues.

Identifying the Role of Block Length in Neural Heat Block to Reduce Temperatures During Infrared Neural Inhibition.

BACKGROUND AND OBJECTIVES: The objective of this study is to assess the hypothesis that the length of axon heated, defined here as block length (BL), affects the temperature required for thermal inhibition of action potential propagation applied using laser heating. The presence of such a phenomenon has implications for how this technique, called infrared neural inhibition (INI), may be applied in a clinically safe manner since it suggests that temperatures required for therapy may be reduced through the proper spatial application of light. Here, we validate the presence of this phenomenon by assessing how the peak temperatures during INI are reduced when two different BLs are applied using irradiation from either one or two adjacent optical fibers. STUDY DESIGN/MATERIALS AND METHODS: Assessment of the role of BL was carried out over two phases. First, a computational proof of concept was performed in the neural conduction simulation environment, NEURON, simulating the response of action potentials to increased temperatures applied at different full-width at half-maxima (FWHM) along axons. Second, ex vivo validation of these predictions was performed by measuring the radiant exposure, peak temperature rise, and FWHM of heat distributions associated with INI from one or two adjacent optical fibers. Electrophysiological assessment of radiant exposures at inhibition threshold were carried out in ex vivo Aplysia californica (sea slug) pleural abdominal nerves ( n = 6), an invertebrate with unmyelinated axons. Measurement of the maximum temperature rise required for induced heat block was performed in a water bath using a fine wire thermocouple. Finally, magnetic resonance thermometry (MRT) was performed on a nerve immersed in saline to assess the elevated temperature distribution at these radiant exposures. RESULTS: Computational modeling in NEURON provided a theoretical proof of concept that the BL is an important factor contributing to the peak temperature required during neural heat block, predicting a 11.7% reduction in temperature rise when the FWHM along an axon is increased by 42.9%. Experimental validation showed that, when using two adjacent fibers instead of one, a 38.5 ± 2.2% (mean ± standard error of the mean) reduction in radiant exposure per pulse per fiber threshold at the fiber output (P = 7.3E-6) is measured, resulting in a reduction in peak temperature rise under each fiber of 23.5 ± 2.1% ( P = 9.3E-5) and 15.0 ± 2.4% ( P = 1.4E-3) and an increase in the FWHM of heating by 37.7 ± 6.4% ( P = 1E-3), 68.4 ± 5.2% ( P = 2.4E-5), and 51.9 ± 9.9% ( P = 1.7E-3) in three MRT slices. CONCLUSIONS: This study provides the first experimental evidence for a phenomenon during the heat block in which the temperature for inhibition is dependent on the BL. While more work is needed to further reduce the temperature during INI, the results highlight that spatial application of the temperature rise during INI must be considered. Optimized implementation of INI may leverage this cellular response to provide optical modulation of neural signals with lower temperatures over greater time periods, which may increase the utility of the technique for laboratory and clinical use. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Removing vessel constriction on the embryonic heart results in changes in valve gene expression, morphology, and hemodynamics.

BACKGROUND: The formation of healthy heart valves throughout embryonic development is dependent on both genetic and epigenetic factors. Hemodynamic stimuli are important epigenetic regulators of valvulogenesis, but the resultant molecular pathways that control valve development are poorly understood. Here we describe how the heart and valves recover from the removal of a partial constriction (banding) of the OFT/ventricle junction (OVJ) that temporarily alters blood flow velocity through the embryonic chicken heart (HH stage 16/17). Recovery is described in terms of 24- and 48-hr gene expression, morphology, and OVJ hemodynamics. RESULTS: Collectively, these studies show that after 24 hr of recovery, important epithelial-mesenchymal transformation (EMT) genes TGFßRIII and Cadherin 11 (CDH11) transcript levels normalize return to control levels, in contrast to Periostin and TGFß,3 which remain altered. In addition, after 48 hr of recovery, TGFß3 and CDH11 transcript levels remain normalized, whereas TGFßRIII and Periostin are down-regulated. Analyses of OFT cushion volumes in the hearts show significant changes, as does the ratio of cushion to cell volume at 24 hr post band removal (PBR). Morphologically, the hearts show visible alteration following band removal when compared to their control age-matched counterparts. CONCLUSIONS: Although some aspects of the genetic/cellular profiles affected by altered hemodynamics seem to be reversed, not all gene expression and cardiac growth normalize following 48 hr of band removal. Developmental Dynamics 247:531-541, 2018. © 2017 Wiley Periodicals, Inc.

Complex decorrelation averaging in optical coherence tomography: a way to reduce the effect of multiple scattering and improve image contrast in a dynamic scattering medium.

We demonstrate that complex decorrelation averaging can reduce the effect of multiple scattering and improve optical coherence tomography (OCT) imaging contrast. Complex decorrelation averaging calculates the product of an A-scan and the complex conjugate of a subsequent A-scan. The resultant signal is the product of the amplitudes and the phase difference. All these resulting complex signals at a particular location are then averaged. We take advantage of the fact that complex averaging, in contrast to conventional magnitude averaging, is sensitive to phase decorrelation. Sample motion that increases signal phase variance results in lower signal magnitude after complex averaging. Such motion preferentially results in a faster decorrelation of the multiple scattering signal when compared to the single scattering signal with each scattering event spreading the phase. This indicates that we may reduce multiple scattering by implementing complex decorrelation averaging to preferentially reduce the magnitude of the multiply scattered light signal in OCT images. By adjusting the time between phase-differenced A-scans, one can regulate the amount of measured decorrelation. We have performed experiments on liquid phantoms that give experimental evidence for this hypothesis. A substantial improvement in OCT image contrast using complex decorrelation averaging is demonstrated.

Supplementation with the Methyl Donor Betaine Prevents Congenital Defects Induced by Prenatal Alcohol Exposure.

BACKGROUND: Despite decades of public education about dire consequences of prenatal alcohol exposure (PAE), drinking alcohol during pregnancy remains prevalent. As high as 40% of live-born infants exposed to alcohol during gestation and diagnosed with fetal alcohol syndrome have congenital heart defects that can be life-threatening. In animal models, the methyl donor betaine, found in foods such as wheat bran, quinoa, beets, and spinach, ameliorated neurobehavioral deficits associated with PAE, but effects on heart development are unknown. METHODS: Previously, we modeled a binge drinking episode during the first trimester in avian embryos. Here, we investigated whether betaine could prevent adverse effects of alcohol on heart development. Embryos exposed to ethanol (EtOH) with and without an optimal dose of betaine (5 µM) were analyzed at late developmental stages. Cardiac morphology parameters were rapidly analyzed and quantified using optical coherence tomography. DNA methylation at early stages was detected by immunofluorescent staining for 5-methylcytosine in sections of embryos treated with EtOH or cotreated with betaine. RESULTS: Compared to EtOH-exposed embryos, betaine-supplemented embryos had higher late-stage survival rates and fewer gross head and body defects than seen after alcohol exposure alone. Betaine also reduced the incidence of late-stage cardiac defects such as absent vessels, abnormal atrioventricular (AV) valves, and hypertrophic ventricles. Furthermore, betaine cotreatment brought measurements of great vessel diameters, interventricular septum thickness, and AV leaflet volumes in betaine-supplemented embryos close to control values. Early-stage 5-methycytosine staining revealed that DNA methylation levels were reduced by EtOH exposure and normalized by co-administration with betaine. CONCLUSIONS: This is the first study demonstrating efficacy of the methyl donor betaine in alleviating cardiac defects associated with PAE. These findings highlight the therapeutic potential of low-concentration betaine doses in mitigating PAE-induced birth defects and have implications for prenatal nutrition policies, especially for women who may not be responsive to folate supplementation.

CUG-BP, Elav-like family member 1 (CELF1) is required for normal myofibrillogenesis, morphogenesis, and contractile function in the embryonic heart.

BACKGROUND: CUG-BP, Elav-like family member 1 (CELF1) is a multifunctional RNA binding protein found in a variety of adult and embryonic tissues. In the heart, CELF1 is found exclusively in the myocardium. However, the roles of CELF1 during cardiac development have not been completely elucidated. RESULTS: Myofibrillar organization is disrupted and proliferation is reduced following knockdown of CELF1 in cultured chicken primary embryonic cardiomyocytes. In vivo knockdown of Celf1 in developing Xenopus laevis embryos resulted in myofibrillar disorganization and a trend toward reduced proliferation in heart muscle, indicating conserved roles for CELF1 orthologs in embryonic cardiomyocytes. Loss of Celf1 also resulted in morphogenetic abnormalities in the developing heart and gut. Using optical coherence tomography, we showed that cardiac contraction was impaired following depletion of Celf1, while heart rhythm remained unperturbed. In contrast to cardiac muscle, loss of Celf1 did not disrupt myofibril organization in skeletal muscle cells, although it did lead to fragmentation of skeletal muscle bundles. CONCLUSIONS: CELF1 is required for normal myofibril organization, proliferation, morphogenesis, and contractile performance in the developing myocardium. Developmental Dynamics 245:854-873, 2016. © 2016 Wiley Periodicals, Inc.

Cardiac neural crest ablation results in early endocardial cushion and hemodynamic flow abnormalities.

Cardiac neural crest cell (CNCC) ablation creates congenital heart defects (CHDs) that resemble those observed in many syndromes with craniofacial and cardiac consequences. The loss of CNCCs causes a variety of great vessel defects, including persistent truncus arteriosus and double-outlet right ventricle. However, because of the lack of quantitative volumetric measurements, less severe defects, such as great vessel size changes and valve defects, have not been assessed. Also poorly understood is the role of abnormal cardiac function in the progression of CNCC-related CHDs. CNCC ablation was previously reported to cause abnormal cardiac function in early cardiogenesis, before the CNCCs arrive in the outflow region of the heart. However, the affected functional parameters and how they correlate with the structural abnormalities were not fully characterized. In this study, using a CNCC-ablated quail model, we contribute quantitative phenotyping of CNCC ablation-related CHDs and investigate abnormal early cardiac function, which potentially contributes to late-stage CHDs. Optical coherence tomography was used to assay early- and late-stage embryos and hearts. In CNCC-ablated embryos at four-chambered heart stages, great vessel diameter and left atrioventricular valve leaflet volumes are reduced. Earlier, at cardiac looping stages, CNCC-ablated embryos exhibit abnormally twisted bodies, abnormal blood flow waveforms, increased retrograde flow percentage, and abnormal cardiac cushions. The phenotypes observed in this CNCC-ablation model were also strikingly similar to those found in an established avian fetal alcohol syndrome model, supporting the contribution of CNCC dysfunction to the development of alcohol-induced CHDs.

Responses of two semiarid conifer tree species to reduced precipitation and warming reveal new perspectives for stomatal regulation.

Relatively anisohydric species are predicted to be more predisposed to hydraulic failure than relatively isohydric species, as they operate with narrower hydraulic safety margins. We subjected co-occurring anisohydric Juniperus monosperma and isohydric Pinus edulis trees to warming, reduced precipitation, or both, and measured their gas exchange and hydraulic responses. We found that reductions in stomatal conductance and assimilation by heat and drought were more frequent during relatively moist periods, but these effects were not exacerbated in the combined heat and drought treatment. Counter to expectations, both species exhibited similar gs temporal dynamics in response to drought. Further, whereas P. edulis exhibited chronic embolism, J. monosperma showed very little embolism due to its conservative stomatal regulation and maintenance of xylem water potential above the embolism entry point. This tight stomatal control and low levels of embolism experienced by juniper refuted the notion that very low water potentials during drought are associated with loose stomatal control and with the hypothesis that anisohydric species are more prone to hydraulic failure than isohydric species. Because direct association of stomatal behaviour with embolism resistance can be misleading, we advocate consideration of stomatal behaviour relative to embolism resistance for classifying species drought response strategies.

Using optical coherence tomography to rapidly phenotype and quantify congenital heart defects associated with prenatal alcohol exposure.

BACKGROUND: The most commonly used method to analyze congenital heart defects involves serial sectioning and histology. However, this is often a time-consuming process where the quantification of cardiac defects can be difficult due to problems with accurate section registration. Here we demonstrate the advantages of using optical coherence tomography, a comparatively new and rising technology, to phenotype avian embryo hearts in a model of fetal alcohol syndrome where a binge-like quantity of alcohol/ethanol was introduced at gastrulation. RESULTS: The rapid, consistent imaging protocols allowed for the immediate identification of cardiac anomalies, including ventricular septal defects and misaligned/missing vessels. Interventricular septum thicknesses and vessel diameters for three of the five outflow arteries were also significantly reduced. Outflow and atrioventricular valves were segmented using image processing software and had significantly reduced volumes compared to controls. This is the first study to our knowledge that has 3D reconstructed the late-stage cardiac valves in precise detail to examine their morphology and dimensions. CONCLUSIONS: We believe, therefore, that optical coherence tomography, with its ability to rapidly image and quantify tiny embryonic structures in high resolution, will serve as an excellent and cost-effective preliminary screening tool for developmental biologists working with a variety of experimental/disease models.

Muscleblind-like 1 is required for normal heart valve development in vivo.

BACKGROUND: Development of the valves and septa of the heart depends on the formation and remodeling of the endocardial cushions in the atrioventricular canal and outflow tract. These cushions are populated by mesenchyme produced from the endocardium by epithelial-mesenchymal transition (EMT). The endocardial cushions are remodeled into the valves at post-EMT stages via differentiation of the mesenchyme and changes in the extracellular matrix (ECM). Transforming growth factor ß (TGFß) signaling has been implicated in both the induction of EMT in the endocardial cushions and the remodeling of the valves at post-EMT stages. We previously identified the RNA binding protein muscleblind-like 1 (MBNL1) as a negative regulator of TGFß signaling and EMT in chicken endocardial cushions ex vivo. Here, we investigate the role of MBNL1 in endocardial cushion development and valvulogenesis in Mbnl1(∆E3/∆E3) mice, which are null for MBNL1 protein. METHODS: Collagen gel invasion assays, histology, immunohistochemistry, real-time RT-PCR, optical coherence tomography, and echocardiography were used to evaluate EMT and TGFß signaling in the endocardial cushions, and morphogenesis, ECM composition, and function of the heart valves. RESULTS: As in chicken, the loss of MBNL1 promotes precocious TGFß signaling and EMT in the endocardial cushions. Surprisingly, this does not lead to the production of excess mesenchyme, but later valve morphogenesis is aberrant. Adult Mbnl1(∆E3/∆E3) mice exhibit valve dysmorphia with elevated TGFß signaling, changes in ECM composition, and increased pigmentation. This is accompanied by a high incidence of regurgitation across both inflow and outflow valves. Mbnl1(∆E3/∆E3) mice also have a high incidence of ostium secundum septal defects accompanied by atrial communication, but do not develop overt cardiomyopathy. CONCLUSIONS: Together, these data indicate that MBNL1 plays a conserved role in negatively regulating TGFß signaling, and is required for normal valve morphogenesis and homeostasis in vivo.

Linking nonstructural carbohydrate dynamics to gas exchange and leaf hydraulic behavior in Pinus edulis and Juniperus monosperma.

Leaf hydraulics, gas exchange and carbon storage in Pinus edulis and Juniperus monosperma, two tree species on opposite ends of the isohydry-anisohydry spectrum, were analyzed to examine relationships between hydraulic function and carbohydrate dynamics. Leaf hydraulic vulnerability, leaf water potential (Ψl ), leaf hydraulic conductance (Kleaf ), photosynthesis (A), stomatal conductance (gs) and nonstructural carbohydrate (NSC) content were analyzed throughout the growing season. Leaf hydraulic vulnerability was significantly lower in the relatively anisohydric J. monosperma than in the more isohydric P. edulis. In P. edulis, Ψl dropped and stayed below 50% loss of leaf hydraulic conductance (P50) early in the day during May, August and around midday in September, leading to sustained reductions in Kleaf . In J. monosperma, Ψl dropped below P50 only during August, resulting in the maintenance of Kleaf during much of the growing season. Mean A and gs during September were significantly lower in P. edulis than in J. monosperma. Foliar total NSC was two to three times greater in J. monosperma than in P. edulis in June, August and September. Consistently lower levels of total NSC in P. edulis suggest that its isohydric strategy pushes it towards the exhaustion of carbon reserves during much of the growing season.

Optical coherence tomography imaging of the patent ductus arteriosus: first known uses in congenital heart disease.

BACKGROUND: Angiography is used to assess ductal morphology and caliber during interventional closure of the ductus arteriosus. We are evaluating the use of optical coherence tomography (OCT) to evaluate ductal anatomy given the potential benefit of superior resolution and lower radiation. METHODS: Standard angiograms were performed on two patients with patent ductus arteriosus prior to device occlusion. OCT was then used to obtain high-resolution three-dimensional vessel reconstructions. Devices were chosen based on angiographic measurements. RESULTS: OCT resulted in excellent three-dimensional anatomic definition, with elliptical narrowest lumenal measurements of 2.2 × 3.1 mm and 1.6 × 2.3 mm, respectively, compared with angiographic measurements of 2.6 and 1.4 mm. CONCLUSIONS: To our knowledge, this is the first reported use of OCT use in pediatric patients outside the coronaries, and in patients with congenital heart disease. We found OCT imaging of the PDA to be feasible, and only used a small amount of additional radiation and contrast. The three-dimensional OCT reconstructions provided additional anatomic information that could potentially improve device selection, and in both cases may have led to choosing larger devices than what was chosen based on angiography. In addition, once the technique is perfected, little or no angiography or fluoroscopy will be required to perform imaging runs, and only a small injection of contrast appears to be sufficient for vessel imaging. However, there are certain limitations to OCT imaging that are unlikely to make it the method of choice specifically for imaging the patent ductus arteriosus, but we have shown its ability to provide high resolution imaging in a relatively simple fashion which may prove useful for other purposes. © 2014 Wiley Periodicals, Inc.

Connecting teratogen-induced congenital heart defects to neural crest cells and their effect on cardiac function.

Neural crest cells play many key roles in embryonic development, as demonstrated by the abnormalities that result from their specific absence or dysfunction. Unfortunately, these key cells are particularly sensitive to abnormalities in various intrinsic and extrinsic factors, such as genetic deletions or ethanol-exposure that lead to morbidity and mortality for organisms. This review discusses the role identified for a segment of neural crest in regulating the morphogenesis of the heart and associated great vessels. The paradox is that their derivatives constitute a small proportion of cells to the cardiovascular system. Findings supporting that these cells impact early cardiac function raises the interesting possibility that they indirectly control cardiovascular development at least partially through regulating function. Making connections between insults to the neural crest, cardiac function, and morphogenesis is more approachable with technological advances. Expanding our understanding of early functional consequences could be useful in improving diagnosis and testing therapies.

Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects?

Alcohol-induced congenital heart defects are frequently among the most life threatening and require surgical correction in newborns. The etiology of these defects, collectively known as fetal alcohol syndrome, has been the focus of much study, particularly involving cellular and molecular mechanisms. Few studies have addressed the influential role of altered cardiac function in early embryogenesis because of a lack of tools with the capability to assay tiny beating hearts. To overcome this gap in our understanding, we used optical coherence tomography (OCT), a nondestructive imaging modality capable of micrometer-scale resolution imaging, to rapidly and accurately map cardiovascular structure and hemodynamics in real time under physiological conditions. In this study, we exposed avian embryos to a single dose of alcohol/ethanol at gastrulation when the embryo is sensitive to the induction of birth defects. Late-stage hearts were analyzed using standard histological analysis with a focus on the atrio-ventricular valves. Early cardiac function was assayed using Doppler OCT, and structural analysis of the cardiac cushions was performed using OCT imaging. Our results indicated that ethanol-exposed embryos developed late-stage valvuloseptal defects. At early stages, they exhibited increased regurgitant flow and developed smaller atrio-ventricular cardiac cushions, compared with controls (uninjected and saline-injected embryos). The embryos also exhibited abnormal flexion/torsion of the body. Our evidence suggests that ethanol-induced alterations in early cardiac function have the potential to contribute to late-stage valve and septal defects, thus demonstrating that functional parameters may serve as early and sensitive gauges of cardiac normalcy and abnormalities.