Hypercapnia Causes Injury of the Cerebral Cortex and Cognitive Deficits in Newborn Piglets.

In critically ill newborns, exposure to hypercapnia (HC) is common and often accepted in neonatal intensive care units to prevent severe lung injury. However, as a "safe" range of arterial partial pressure of carbon dioxide levels in neonates has not been established, the potential impact of HC on the neurodevelopmental outcomes in these newborns remains a matter of concern. Here, in a newborn Yorkshire piglet model of either sex, we show that acute exposure to HC induced persistent cortical neuronal injury, associated cognitive and learning deficits, and long-term suppression of cortical electroencephalogram frequencies. HC induced a transient energy failure in cortical neurons, a persistent dysregulation of calcium-dependent proapoptotic signaling in the cerebral cortex, and activation of the apoptotic cascade, leading to nuclear deoxyribonucleic acid fragmentation. While neither 1 h of HC nor the rapid normalization of HC was associated with changes in cortical bioenergetics, rapid resuscitation resulted in a delayed onset of synaptosomal membrane lipid peroxidation, suggesting a dissociation between energy failure and the occurrence of synaptosomal lipid peroxidation. Even short durations of HC triggered biochemical responses at the subcellular level of the cortical neurons resulting in altered cortical activity and impaired neurobehavior. The deleterious effects of HC on the developing brain should be carefully considered as crucial elements of clinical decisions in the neonatal intensive care unit.

Glaucoma Drainage Device Surgery Outcomes in Children With Uveitic Glaucoma.

PURPOSE: To evaluate outcomes of glaucoma drainage device (GDD) implantation children with uveitic glaucoma. DESIGN: Retrospective interventional case series. METHODS: Success was defined as intraocular pressure (IOP) ≥5 and ≤21 mm Hg. Failure was defined at final follow-up when the IOP was outside the success criterion, and visual function was no perception of light or if further glaucoma surgery (excluding removal of intraluminal stent suture or needling) was required. RESULTS: Fifty eyes of 36 children with uveitic glaucoma underwent GDD implantation. Mean age at surgery was 10.1±3.1 years (range 5-17) with a mean follow-up of 113±61 months (range 8-228). Mean cumulative probabilities of success (95% CI) were 0.98 (0.86-1.00) at 1 year, 0.87 (0.73-0.94) at 5 years, and 0.59 (0.32-0.78) at 15 years. Fourteen tubes were classified as failed, with 12 due to uncontrolled IOP (11 eyes required a second GDD); 1 eye, removal of the tube due to plate exposure; and 1 eye, lost light perception. Postoperative complications occurred in 36% of patients and included hypotony (22%), tube exposure (6%), tube obstruction (4%), corneal decompensation (2%), and cystoid macular edema (2%). Visual acuity remained stable (preoperation 0.35±0.42 vs postoperation 0.45±0.67, P = .49). IOP was significantly reduced from 31.4±7.5 mm Hg to 14.4±5.1 mm Hg (P < .0001) as were the number of glaucoma medications 3.5±1.0 vs 1.1±1.3 (P < .0001). CONCLUSIONS: Refractory pediatric uveitic glaucoma can be treated successfully by GDD implantation. Further interventions to manage consequences of glaucoma or the underlying disease are common, and visual function is maintained in the majority of cases.

Computational analysis of cortical neuronal excitotoxicity in a large animal model of neonatal brain injury.

BACKGROUND: Neonatal hypoxic brain injury is a major cause of intellectual and developmental disability. Hypoxia causes neuronal dysfunction and death in the developing cerebral cortex due to excitotoxic Ca2+-influx. In the translational piglet model of hypoxic encephalopathy, we have previously shown that hypoxia overactivates Ca2+/Calmodulin (CaM) signaling via Sarcoma (Src) kinase in cortical neurons, resulting in overexpression of proapoptotic genes. However, identifying the exact relationship between alterations in neuronal Ca2+-influx, molecular determinants of cell death, and the degree of hypoxia in a dynamic system represents a significant challenge. METHODS: We used experimental and computational methods to identify molecular events critical to the onset of excitotoxicity-induced apoptosis in the cerebral cortex of newborn piglets. We used 2-3-day-old piglets (normoxic [Nx], hypoxic [Hx], and hypoxic + Src-inhibitor-treatment [Hx+PP2] groups) for biochemical analysis of ATP production, Ca2+-influx, and Ca2+/CaM-dependent protein kinase kinase 2 (CaMKK2) expression. We then used SimBiology to build a computational model of the Ca2+/CaM-Src-kinase signaling cascade, simulating Nx, Hx, and Hx+PP2 conditions. To evaluate our model, we used Sobol variance decomposition, multiparametric global sensitivity analysis, and parameter scanning. RESULTS: Our model captures important molecular trends caused by hypoxia in the piglet brain. Incorporating the action of Src kinase inhibitor PP2 further validated our model and enabled predictive analysis of the effect of hypoxia on CaMKK2. We determined the impact of a feedback loop related to Src phosphorylation of NMDA receptors and activation kinetics of CaMKII. We also identified distinct modes of signaling wherein Ca2+ level alterations following Src kinase inhibition may not be a linear predictor of changes in Bax expression. Importantly, our model indicates that while pharmacological pre-treatment significantly reduces the onset of abnormal Ca2+-influx, there exists a window of intervention after hypoxia during which targeted modulation of Src-NMDAR interaction kinetics in combination with PP2 administration can reduce Ca2+-influx and Bax expression to similar levels as pre-treatment. CONCLUSIONS: Our model identifies new dynamics of critical components in the Ca2+/CaM-Src signaling pathway leading to neuronal injury and provides a feasible framework for drug efficacy studies in translational models of neonatal brain injury for the prevention of intellectual and developmental disabilities.

Study of Optimal Perimetric Testing In Children (OPTIC): developing consensus and setting research priorities for perimetry in the management of children with glaucoma.

BACKGROUND: Perimetry is important in the management of children with glaucoma, but there is limited evidence-based guidance on its use. We report an expert consensus-based study to update guidance and identify areas requiring further research. METHODS: Experts were invited to participate in a modified Delphi consensus process. Panel selection was based on clinical experience of managing children with glaucoma and UK-based training to minimise diversity of view due to healthcare setting. Questionnaires were delivered electronically, and analysed to establish 'agreement'. Divergence of opinions was investigated and resolved where possible through further iterations. RESULTS: 7/9 experts invited agreed to participate. Consensus (≥5/7 (71%) in agreement) was achieved for 21/26 (80.8%) items in 2 rounds, generating recommendations to start perimetry from approximately 7 years of age (IQR: 6.75-7.25), and use qualitative methods in conjunction with automated reliability indices to assess test quality. There was a lack of agreement about defining progressive visual field (VF) loss and methods for implementing perimetry longitudinally. Panel members highlighted the importance of informing decisions based upon individual circumstances-from gauging maturity/capability when selecting tests and interpreting outcomes, to accounting for specific clinical features (e.g. poor IOP control and/or suspected progressive VF loss) when making decisions about frequency of testing. CONCLUSIONS: There is commonality of expert views in relation to implementing perimetry and interpreting test quality in the management of children with glaucoma. However, there remains a lack of agreement about defining progressive VF loss, and utilising perimetry over an individuals' lifetime, highlighting the need for further research.

Epidermal Growth Factor Receptor Inhibition Reverses Cellular and Transcriptomic Alterations Induced by Hypoxia in the Neonatal Piglet Brain.

Acute hypoxia (HX) causes extensive cellular damage in the developing human cerebral cortex. We found increased expression of activated-EGFR in affected cortical areas of neonates with HX and investigated its functional role in the piglet, which displays a highly evolved, gyrencephalic brain, with a human-like maturation pattern. In the piglet, HX-induced activation of EGFR and Ca2+/calmodulin kinase IV (CaMKIV) caused cell death and pathological alterations in neurons and glia. EGFR blockade inhibited CaMKIV activation, attenuated neuronal loss, increased oligodendrocyte proliferation, and reversed HX-induced astrogliosis. We performed for the first time high-throughput transcriptomic analysis of the piglet cortex to define molecular responses to HX and to uncover genes specifically involved in EGFR signaling in piglet and human brain injury. Our results indicate that specific molecular responses modulated by EGFR may be targeted as a therapeutic strategy for HX injury in the neonatal brain.

International Study of Childhood Glaucoma.

PURPOSE: To ascertain the types of childhood glaucoma managed at major international centers, current clinical practice, and intraocular pressure (IOP) control and visual acuity (VA) outcomes. DESIGN: Prospective, multicenter, consecutive case series. PARTICIPANTS: All children with newly diagnosed glaucoma in at least 1 eye who fulfilled the Childhood Glaucoma Research Network (CGRN) definition of childhood glaucoma were recruited over a 1-year period with the aim of 18 months follow up. METHODS: Demographic, clinical, management data (including complications), and outcomes (IOP and VA) were entered in a secure online database. All cases included in the outcome analysis had a minimum of 6 months follow-up. MAIN OUTCOME MEASURES: The management of childhood glaucoma, IOP control, and VA outcomes. RESULTS: A total of 441 children (691 eyes) with newly diagnosed glaucoma were enrolled from 17 international centers. Approximately 60% of patients came from 2 centers in India; however, 47.5% of Indian patients had no or less than 6 months of follow-up outcome data from diagnosis. Primary congenital glaucoma (PCG) was the most common diagnosis (45.4%, n = 314 eyes). There was a statistically significant association between diagnosis and ethnicity/race (P < 0.001), with PCG more frequent in nonwhite patients, glaucoma associated with acquired conditions more frequent in South Asian patients, and glaucoma after cataract surgery more frequent in white patients. The initial surgical procedure of choice for eyes with PCG significantly differed by country. Angle surgery alone was first line in centers in the United States, United Kingdom, Germany, Saudi Arabia, Singapore, and Israel (Group 1), whereas combined trabeculotomy-trabeculectomy was the first-line procedure for PCG in centers in India and Ghana (Group 2). There was no significant difference in IOP control nor VA between the 2 groups. CONCLUSIONS: The most common diagnoses in this international study of children with newly diagnosed glaucoma in order of frequency were PCG, glaucoma after congenital idiopathic cataract surgery, and glaucoma associated with trauma. Indian children had a disproportionately high loss to follow-up rate. Despite international differences in the surgical approach to PCG, there was no statistically significant difference in IOP or VA outcomes. We hope the results of this study will inform key areas of future international, collaborative clinical research in childhood glaucoma.

From Conventional Angle Surgery to 360-Degree Trabeculotomy in Pediatric Glaucoma.

PURPOSE: To describe the transition from conventional angle surgery (CAS), trabeculotomy with rigid probe or goniotomy, to 360-degree trabeculotomy assisted with microcatheter (MCT). DESIGN: Retrospective comparative interventional case series. METHODS: Review of consecutive children with glaucoma undergoing angle surgery, including cases with previous surgery, from January 2012 until March 2018 at Moorfields Eye Hospital. Main outcome measure was success rate, defined as intraocular pressure (IOP) ≤21 mm Hg with a minimum of 20% of IOP reduction and no further glaucoma surgery (complete success: without the need of glaucoma drops; qualified success: drops were needed to keep the IOP under control). RESULTS: Among the 106 eyes (77 patients) included were 54 MCT and 52 CAS eyes. At last visit, after a single surgery, qualified success was 85% (46 eyes) in MCT and 37% (19 eyes) in CAS. Complete success was 69% (37 cases) in MCT and 23% (12 cases) in CAS. The mean (95% confidence interval) change in axial length after surgery was -0.03 mm (-0.34 to 0.40) for MCT and +1.35 mm (-0.64 to 1.62) for CAS (P < .001). The percentage of IOP reduction was 52.1% in MCT and 45.5% in CAS (P = .1616). Further glaucoma surgery was required in 5.5% (3) in MCT and 63.4% (33) in CAS. At 1 year, 94.3% of MCT cases achieved qualified success compared to 34.6% of CAS (P < .0001). No significant complications were found on either group. CONCLUSION: MCT achieved better results with significantly lower reoperation rates. The transition from CAS to MCT can be easily achieved, even in difficult cases or those previously operated.

A new paradigm for delivering personalised care: integrating genetics with surgical interventions in BEST1 mutations.

BACKGROUND: The availability and reduced cost of genotyping has improved gene susceptibility testing and our scientific understanding of disease pathophysiology. Whilst several personalised translational models exist within medical frameworks, genetic-based surgical therapy is a translational application not widely used in surgical specialties. METHOD: We present a clinical series of five patients with genetically confirmed bestrophinopathy and malignant glaucoma (MG). Patients were followed up for 12 months or more after receiving surgical intervention to manage refractory intraocular pressure (IOP) resistant to medical treatment. FINDINGS: Patients with BEST1 gene mutations are at higher risk of MG after filtration surgery. A multi-disciplinary approach after four patients experienced poor outcomes concluded that traditional first-line glaucoma surgery was not sufficient to prevent visual loss. A fifth patient presenting with the identified at-risk phenotype underwent primary pars plana vitrectomy, with pars plana Baerveldt tube insertion, successfully preventing MG and had no glaucoma progression after 5 years. INTERPRETATION: We provide proof-of-principle that genetic analysis can be used to inform the selection of surgical therapy to improve outcomes. In this case, a refinement of current surgical methods to avoid MG. Although challenges remain, personalised surgery has the potential to improve clinical outcomes beyond the scope of current surgical practice.

Optical Coherence Tomography Findings After Childhood Lensectomy.

Purpose: To explore the impact of childhood lensectomy on posterior segment development. Methods: Cross-sectional observational study at children's eye clinics at a tertiary referral center in London, UK. We included 45 children age 4 to 16 years with healthy eyes and 38 who had undergone lensectomy. We acquired posterior segment optical coherence tomography scans of both eyes. We used parametric and nonparametric tests in SPSS24 for the comparison of parameters between groups and within individuals; a P value less than 0.05 was considered significant. The main outcome measures were foveal pit depth and subfoveal choroidal thickness (CT). Secondary outcomes were inner and outer ring CT and photoreceptor layer parameters, macular and peripapillary retinal nerve fiber layer thickness. Results: Foveal pit depth and subfoveal CT are significantly reduced in eyes that have undergone lensectomy compared with nonoperated eyes. Inner ring CT and outer ring CT are reduced. Foveal inner retinal layer thickness is increased. Mean inner retinal and outer nuclear layer thickness are not affected. Conclusions: Childhood lensectomy is associated with a reduction in developmental foveal pit deepening and lack of developmental thickening of the posterior choroid. Mechanical and optical disruption of foveal and subfoveal choroidal development may affect structural foveal development after childhood lensectomy.

The Oculome Panel Test: Next-Generation Sequencing to Diagnose a Diverse Range of Genetic Developmental Eye Disorders.

PURPOSE: To develop a comprehensive next-generation sequencing panel assay that screens genes known to cause developmental eye disorders and inherited eye disease and to evaluate its diagnostic yield in a pediatric cohort with malformations of the globe, anterior segment anomalies, childhood glaucoma, or a combination thereof. DESIGN: Evaluation of diagnostic test. PARTICIPANTS: Two hundred seventy-seven children, 0 to 16 years of age, diagnosed with nonsyndromic or syndromic developmental eye defects without a genetic diagnosis. METHODS: We developed a new oculome panel using a custom-designed Agilent SureSelect QXT target capture method (Agilent Technologies, Santa Clara, CA) to capture and perform parallel high-throughput sequencing analysis of 429 genes associated with eye disorders. Bidirectional Sanger sequencing confirmed suspected pathogenic variants. MAIN OUTCOME MEASURES: Collated clinical details and oculome molecular genetic results. RESULTS: The oculome design covers 429 known eye disease genes; these are subdivided into 5 overlapping virtual subpanels for anterior segment developmental anomalies including glaucoma (ASDA; 59 genes), microphthalmia-anophthalmia-coloboma (MAC; 86 genes), congenital cataracts and lens-associated conditions (70 genes), retinal dystrophies (RET; 235 genes), and albinism (15 genes), as well as additional genes implicated in optic atrophy and complex strabismus (10 genes). Panel development and testing included analyzing 277 clinical samples and 3 positive control samples using Illumina sequencing platforms; more than 30× read depth was achieved for 99.5% of the targeted 1.77-Mb region. Bioinformatics analysis performed using a pipeline based on Freebayes and ExomeDepth to identify coding sequence and copy number variants, respectively, resulted in a definitive diagnosis in 68 of 277 samples, with variability in diagnostic yield between phenotypic subgroups: MAC, 8.2% (8 of 98 cases solved); ASDA, 24.8% (28 of 113 cases solved); other or syndromic, 37.5% (3 of 8 cases solved); RET, 42.8% (21 of 49 cases solved); and congenital cataracts and lens-associated conditions, 88.9% (8 of 9 cases solved). CONCLUSIONS: The oculome test diagnoses a comprehensive range of genetic conditions affecting the development of the eye, potentially replacing protracted and costly multidisciplinary assessments and allowing for faster targeted management. The oculome enabled molecular diagnosis of a significant number of cases in our sample cohort of varied ocular birth defects.

Childhood Lensectomy Is Associated with Static and Dynamic Reduction in Schlemm Canal Size: A Biomechanical Hypothesis of Glaucoma after Lensectomy.

PURPOSE: To compare Schlemm canal (SC) and trabecular meshwork (TM) in children with healthy eyes and those with and without glaucoma after lensectomy. DESIGN: Cross-sectional observational study. PARTICIPANTS: Fifty children 4 to 16 years of age with healthy eyes and 48 children who underwent lensectomy (124 healthy and 72 postlensectomy eyes). METHODS: Anterior segment (AS) OCT (Tomey SS-1000 CASIA; Tomey, Nagoya, Japan) of the nasal iridocorneal angle at 2 levels of accommodative effort (2.5 diopters [D] and 15 D). For each parameter and state of accommodation, a random effects model was fitted to estimate differences between healthy eyes and eyes with history of lensectomy. MAIN OUTCOME MEASURES: Dimensions of SC and TM and conventional AS OCT iridocorneal angle measurements. RESULTS: The horizontal diameter of SC and its cross-sectional area (CSA) are significantly smaller in eyes that have undergone lensectomy versus healthy eyes. Accommodative effort increases SC size in healthy eyes, but not in eyes that have undergone lensectomy. CONCLUSIONS: Lensectomy is associated with a reduction in SC size and a loss of physiologic SC dilatation during accommodative effort, which may reflect a reduction in outflow facility and may contribute to the development of glaucoma after lensectomy.

Biomechanical Responses of Neonatal Brachial Plexus to Mechanical Stretch.

This study investigated the biomechanical responses of neonatal piglet brachial plexus (BP) segments-root/trunk, chord, and nerve at two different rates, 0.01 mm/second (quasistatic) and 10 mm/second (dynamic)-and compared their response to another peripheral nerve (tibial). Comparisons of mechanical responses at two different rates reported a significantly higher maximum load, maximum stress, and Young's modulus (E) values when subjected to dynamic rate. Among various BP segments, maximum stress was significantly higher in the nerve segments, followed by chord and then the root/trunk segments except no differences between chord and root/trunk segments at quasistatic rate. E values exhibited similar behavior except no differences between the chord and root/trunk segments at both rates and no differences between chord and nerve segments at quasistatic rate. No differences were observed in the strain values. When compared with the tibial nerve, only mechanical properties of BP nerves were similar to the tibial nerve. Mechanical stresses and E values reported in BP root/trunk and chord segments were significantly lower than tibial nerve at both rates. When comparing the failure pattern, at quasistatic rate, necking was observed at maximum load, before a complete rupture occurred. At dynamic rate, partial rupture at maximum load, followed by a full rupture, was observed. Occurrence of the rate-dependent failure phenomenon was highest in the root/trunk segments followed by chord and nerve segments. Differences in the maximum stress, E values, and failure pattern of BP segments confirm variability in their anatomical structure and warrant future histological studies to better understand their stretch responses.

Functional vision and quality of life in children with microphthalmia/anophthalmia/coloboma-a cross-sectional study.

PURPOSE: To determine the child's and parental perception of functional visual ability (FVA), vision-related and health-related quality of life (VR-QoL, HR-QoL) in children with microphthalmia/anophthalmia/coloboma (MAC). METHODS: Between June 25, 2014, and June 3, 2015, we carried out a cross-sectional observational study at Moorfields Eye Hospital, London, UK, enrolling 45 children 2-16 years of age with MAC attending our clinics, and their parents. To assess FVA, VR-QoL, and HR-QoL we asked participants to complete three validated tools, the Cardiff Visual Ability Questionnaire for Children (CVAQC), the Impact of Vision Impairment for Children (IVI-C) instrument, and the PedsQL V 4.0. The main outcome measures were the FVA, VR-QoL, and HR-QoL scores, reported by children and parents. RESULTS: In children with MAC, FVA is moderately reduced, with a median CVAQC score of -1.4 (IQR, -2.4 to 0.4; range, -3.0 [higher FVA] to +2.8 [lower FVA]). VR-QoL and HR-QoL are greatly reduced, with an IVI-C median score of 63 (IQR, 52-66; normal VR-QoL, 96), a median self-reported PedsQL score of 77 (IQR, 71-90; normal HR-QoL, 100) and parental score of 79 (IQR, 61-93), and a family impact score of 81 (67-93). Psychosocial well-being scores are lower than physical well-being scores. Parents and children have a different perception of the impact of the condition on the child's HR-QoL. CONCLUSIONS: MAC has a significant impact on a child's FVA and QoL, similar to that described by children with acute lymphoblastic leukaemia and chronic systemic conditions. Children and families may benefit from psychosocial support.

Noninvasive monitoring of brain edema after hypoxia in newborn piglets.

BackgroundDevelopment of cerebral edema after brain injury carries a high risk for brain damage and death. The present study tests the ability of a noninvasive cerebral edema monitoring system that uses near-infrared spectroscopy (NIRS) with water as the chromophore of interest to detect brain edema following hypoxia.MethodsVentilated piglets were exposed to hypoxia for 1 h, and then returned to normal oxygen levels for 4 h. An NIRS sensor was placed on the animal's head at baseline, and changes in light attenuation were converted to changes in H2O. Cerebral water content and aquaporin-4 protein (AQP4) expression were measured.ResultsThe system detected changes in NIRS-derived water signal as early as 2 h after hypoxia, and provided fivefold signal amplification, representing a 10% increase in brain water content and a sixfold increase in AQP4, 4 h after hypoxia. Changes in water signal correlated well with changes in cerebral water content (R=0.74) and AQP4 expression (R=0.97) in the piglet brain.ConclusionThe data show that NIRS can detect cerebral edema early in the injury process, thus providing an opportunity to initiate therapy at an earlier and more effective time-point after an insult than is available with current technology.

Effect of Concurrent Src Kinase Inhibition with Short-Duration Hypothermia on Ca2+/Calmodulin Kinase IV Activity and Neuropathology after Hypoxia-Ischemia in the Newborn Swine Brain.

BACKGROUND: Hypoxia-ischemia (HI) results in increased activation of Ca2+/calmodulin kinase IV (CaM kinase IV) mediated by Src kinase. Therapeutic hypothermia ameliorates neuronal injury in the newborn. HYPOTHESIS: Inhibition of Src kinase concurrently with hypothermia further attenuates the hypoxia-induced increased activation of CaM kinase IV compared with hypothermia alone. DESIGN/METHODS: Ventilated piglets were exposed to HI, received saline or a selective Src kinase inhibitor (PP2), and were cooled to 33°C. Neuropathology, adenosine triphosphate (ATP) and phosphocreatine (PCr) concentrations, and CaM kinase IV activity were determined. RESULTS: The neuropathology mean score (mean ± SD) was 0.4 ± 0.43 in normoxia-normothermia (p < 0.05 vs. hypoxia-normothermia), 3.5 ± 0.89 in hypoxia-normothermia (p < 0.05 vs. normoxia-normothermia), 0.7 ± 0.73 in hypoxia-hypothermia (p < 0.05 vs. normoxia-normothermia), and 0.5 ± 0.70 in normoxia-hypothermia (p < 0.05 vs. hypoxia-normothermia). The CaM kinase IV activity in cerebral tissue (pmol Pi/mg protein/min; mean ± SD) was 2,002 ± 729 in normoxia-normothermia, 1,704 ± 18 in normoxia-hypothermia, 6,017 ± 2,510 in hypoxia-normothermia, 4,104 ± 542 in hypoxia-hypothermia (p < 0.05 vs. normoxia-hypothermia), and 2,165 ± 415 in hypoxia-hypothermia with PP2 (p < 0.05 vs. hypoxia-hypothermia). The hypoxic groups with and without hypothermia or Src kinase inhibitor were comparable in the levels of ATP and PCr, indicating that they were similar in their degree of energy failure prior to treatments. Hypothermia or Src kinase inhibitor (PP2) did not restore the ATP and PCr levels. CONCLUSIONS: Hypothermia and Src kinase inhibition attenuated apoptotic cell death and improved neuropathology after hypoxia. The combination of short-duration hypothermia with Src kinase inhibition following hypoxia further attenuates the increased activation of CaM kinase IV compared to hypothermia alone in the newborn swine brain.

Comparison of Quality and Output of Different Optimal Perimetric Testing Approaches in Children With Glaucoma.

Importance: There is limited evidence to support the development of guidance for visual field testing in children with glaucoma. Objective: To compare different static and combined static/kinetic perimetry approaches in children with glaucoma. Design, Setting, and Participants: Cross-sectional, observational study recruiting children prospectively between May 2013 and June 2015 at 2 tertiary specialist pediatric ophthalmology centers in London, England (Moorfields Eye Hospital and Great Ormond Street Hospital). The study included 65 children aged 5 to 15 years with glaucoma (108 affected eyes). Main Outcomes and Measures: A comparison of test quality and outcomes for static and combined static/kinetic techniques, with respect to ability to quantify glaucomatous loss. Children performed perimetric assessments using Humphrey static (Swedish Interactive Thresholding Algorithm 24-2 FAST) and Octopus combined static tendency-oriented perimetry/kinetic perimetry (isopter V4e, III4e, or I4e) in a single sitting, using standardized clinical protocols, administered by a single examiner. Information was collected about test duration, completion, and quality (using automated reliability indices and our qualitative Examiner-Based Assessment of Reliability score). Perimetry outputs were scored using the Aulhorn and Karmeyer classification. One affected eye in 19 participants was retested with Swedish Interactive Thresholding Algorithm 24-2 FAST and 24-2 standard algorithms. Results: Sixty-five children (33 girls [50.8%]), with a median age of 12 years (interquartile range, 9-14 years), were tested. Test quality (Examiner-Based Assessment of Reliability score) improved with increasing age for both Humphrey and Octopus strategies and were equivalent in children older than 10 years (McNemar test, χ2 = 0.33; P = .56), but better-quality tests with Humphrey perimetry were achieved in younger children (McNemar test, χ2 = 4.0; P = .05). Octopus and Humphrey static MD values worse than or equal to -6 dB showed disagreement (Bland-Altman, mean difference, -0.70; limit of agreement, -7.74 to 6.35) but were comparable when greater than this threshold (mean difference, -0.03; limit of agreement, -2.33 to 2.27). Visual field classification scores for static perimetry tests showed substantial agreement (linearly weighted κ, 0.79; 95% CI, 0.65-0.93), although 25 of 80 (31%) were graded with a more severe defect for Octopus static perimetry. Of the 7 severe cases of visual field loss (grade 5), 5 had lower kinetic than static classification scores. Conclusions and Relevance: A simple static perimetry approach potentially yields high-quality results in children younger than 10 years. For children older than 10 years, without penalizing quality, the addition of kinetic perimetry enabled measurement of far-peripheral sensitivity, which is particularly useful in children with severe visual field restriction.

Effect of Src Kinase inhibition on Cytochrome c, Smac/DIABLO and Apoptosis Inducing Factor (AIF) Following Cerebral Hypoxia-Ischemia in Newborn Piglets.

We have previously shown that cerebral Hypoxia-ischemia (HI) results in activation of Src kinase in the newborn piglet brain. We investigated the regulatory mechanism by which the pre-apoptotic proteins translocate from mitochondria to the cytosol during HI through the Src kinase. Newborn piglets were divided into 3 groups (n = 5/group): normoxic (Nx), HI and HI pre-treated with Src kinase inhibitor PP2 (PP2 + HI). Brain tissue HI was verified by neuropathological analysis and by Adenosine Triphosphate (ATP) and Phosphocreatine (PCr) levels. We used western blots, immunohistochemistry, H&E and biochemical enzyme assays to determine the role of Src kinase on mitochondrial membrane apoptotic protein trafficking. HI resulted in decreased ATP and PCr levels, neuropathological changes and increased levels of cytochrome c, Smac/DIABLO and AIF in the cytosol while their levels were decreased in mitochondria compared to Nx. PP2 decreased the cytosolic levels of pre-apoptotic proteins, attenuated the neuropathological changes and apoptosis and decreased the HI-induced increased activity of caspase-3. Our data suggest that Src kinase may represent a potential target that could interrupt the enzymatic activation of the caspase dependent cell death pathway.

FAK-Src-paxillin system expression and disease outcome in human neuroblastoma.

BACKGROUND: Neuroblastoma (NB) often presents with metastatic disease and poor survival. The need for new prognostic markers remains invaluable. The FAK-Src-Paxillin protein system is associated with aggressive phenotype in adult malignancies but is largely unexplored in pediatric NB. OBJECTIVE: To assess FAK-Src-Paxillin protein expression in human NB cell lines and clinical cytology material and to delineate its association with survival. DESIGN/METHODS: Western blot and immunohistochemistry were applied for FAK-Src-Paxillin expression in NB cell lines and 23 human cytology specimens, respectively. Protein expression in human clinical samples was correlated with clinicopathological parameters, MYCN amplification and survival. RESULTS: FAK, Src and Paxillin proteins are expressed in human NB cells lines, and can be detected in clinical cytology specimens from NB patients, (59%, 32% and 33% respectively). Simultaneous FAK-Src-Paxillin expression was noted in 30% of NB patients. Children with concomitant positivity FAK, Src, and Paxillin tumors, as well as MYCN amplification, had increased mortality compared to those without. CONCLUSIONS: FAK-Src-Paxillin system is a marker of unfavorable prognosis for human NB patients but also a promising therapeutic target.

Effects of Src Kinase Inhibition on Expression of Protein Tyrosine Phosphatase 1B after Brain Hypoxia in a Piglet Animal Model.

BACKGROUND: Protein tyrosine phosphatases (PTPs) in conjunction with protein tyrosine kinases (PTKs) regulate cellular processes by posttranslational modifications of signal transduction proteins. PTP nonreceptor type 1B (PTP-1B) is an enzyme of the PTP family. We have previously shown that hypoxia induces an increase in activation of a class of nonreceptor PTK, the Src kinases. In the present study, we investigated the changes that occur in the expression of PTP-1B in the cytosolic component of the brain of newborn piglets acutely after hypoxia as well as long term for up to 2 weeks. METHODS: Newborn piglets were divided into groups: normoxia, hypoxia, hypoxia followed by 1 day and 15 days in FiO2 0.21, and hypoxia pretreated with Src kinase inhibitor PP2, prior to hypoxia followed by 1 day and 15 days. Hypoxia was achieved by providing 7% FiO2 for 1 hour and PTP-1B expression was measured via immunoblotting. RESULTS: PTP-1B increased posthypoxia by about 30% and persisted for 2 weeks while Src kinase inhibition attenuated the expected PTP-1B-increased expression. CONCLUSIONS: Our study suggests that Src kinase mediates a hypoxia-induced increased PTP-1B expression.

Effects of Src kinase inhibition on expression of pro-caspase-2 after brain hypoxia in a piglet animal model.

Caspase-2 has features of both initiator and effector caspases. Previously, we have shown that brain hypoxia-induced production of caspases 1, 3, 8, and 9 is Src kinase mediated, a nonreceptor intracellular family of kinases. The present study tests the hypothesis that hypoxia results in increased expression of caspase-2 and this effect is mediated by Src kinase. Two to three days old newborn piglets were subjected to normoxia, hypoxia (Hx, FiO2 7%), and Src kinase inhibition (using PP2, 1 mg/kg, intravenous), followed by 30 min of acute hypoxia (Hx+PP2). ATP and phosphocreatine were determined biochemically to verify energy molecule depletion in the hypoxic groups. The cytosolic brain function was isolated and a western blot analysis was carried out using an antibody specific for the caspase-2. The immune-complex band density was expressed as OD/mm. Caspase-2 expression was increased two-fold in the Hx group. After Src kinase inhibition followed by hypoxia, caspase-2 expression was similar to normoxia levels. We conclude that hypoxia results in increased expression of caspase-2 protein in the cytosolic fraction of the cerebral cortex of the newborn piglets. This increase is mediated by Src kinase.