ABSTRACT
PURPOSE: Targeted drug delivery to the optic nerve head may be useful in the preclinical study and later clinical management of optic neuropathies, however, there are no FDA-approved drug delivery systems to achieve this. The purpose of this work was to develop an optic nerve head drug delivery technique. METHODS: Different strategies to approach the optic nerve head were investigated, including standard intravitreal and retroorbital injections. A novel SupraChoroidal-to-Optic-NervE (SCONE) delivery was optimized by creating a sclerotomy and introducing a catheter into the suprachoroidal space. Under direct visualization, the catheter was guided to the optic nerve head. India ink was injected. The suprachoroidal approach was performed in New Zealand White rabbit eyes in vivo (25 animals total). Parameters, including microneedle size and design, catheter design, and catheter tip angle, were optimized ex vivo and in vivo. RESULTS: Out of the candidate optic nerve head approaches, intravitreal, retroorbital, and suprachoroidal approaches were able to localize India ink to within 2 mm of the optic nerve. The suprachoroidal approach was further investigated, and after optimization, was able to deposit India ink directly within the optic nerve head in up to 80% of attempts. In eyes with successful SCONE delivery, latency and amplitude of visual evoked potentials was not different than the naïve untreated eye. CONCLUSIONS: SCONE delivery can be used for targeted drug delivery to the optic nerve head of rabbits without measurable toxicity measured anatomically or functionally. Successful development of this system may yield novel opportunities to study optic nerve head-specific drug delivery in animal models, and paradigm-shifting management strategies for treating optic neuropathies. TRANSLATIONAL RELEVANCE: Here we demonstrate data on a new method for targeted delivery to the optic nerve head, addressing a significant unmet need in therapeutics for optic neuropathies.
Subject(s)
Drug Delivery Systems , Animals , Rabbits , Choroid , Optic Nerve/drug effects , Evoked Potentials, Visual/drug effects , Optic Disk , Intravitreal Injections , Needles , CarbonABSTRACT
BACKGROUND: Flash visual evoked potentials (FVEPs) are a reliable method for protecting visual function during spine surgery in prone position. However, the popularization and application of FVEPs remain limited due to the unclear influence of various anesthetics on FVEPs. Exploring the effects of anesthetic drugs on FVEP and establishing appropriate anesthesia maintenance methods are particularly important for promoting and applying FVEP. According to the conventional concept, inhaled narcotic drugs significantly affect the success of FVEP monitoring, FVEP extraction, and interpretation. Nonetheless, our previous study demonstrated that sevoflurane-propofol balanced anesthesia was a practicable regimen for FVEPs. Desflurane is widely used in general anesthesia for its rapid recovery properties. As the effect of desflurane on FVEP remains unclear, this trial will investigate the effect of different inhaled concentrations of desflurane anesthesia on amplitude of FVEPs during spine surgery, aiming to identify more feasible anesthesia schemes for the clinical application of FVEP. METHODS/ DESIGN: A total of 70 patients undergoing elective spinal surgery will be enrolled in this prospective, randomized controlled, open-label, patient-assessor-blinded, superiority trial and randomly assigned to the low inhaled concentration of desflurane group (LD group) maintained with desflurane-propofolremifentanil-balanced anesthesia or high inhaled concentration of desflurane group (HD group) maintained with desflurane-remifentanil anesthesia maintenance group at a ratio of 1:1. All patients will be monitored for intraoperative FVEPs, and the baseline will be measured half an hour after induction under total intravenous anesthesia (TIVA). After that, patients will receive 0.5 minimum alveolar concentration (MAC) of desflurane combined with propofol and remifentanil for anesthesia maintenance in the LD group, while 0.7-1.0 MAC of desflurane and remifentanil will be maintained in the HD group. The primary outcome is the N75-P100 amplitude 1 h after the induction of anesthesia. We intend to use the dual measure evaluation, dual data entry, and statistical analysis by double trained assessors to ensure the reliability and accuracy of the results. DISCUSSION: This randomized controlled trial aims to explore the superiority effect of low inhaled concentration of desflurane combined with propofolremifentanil-balanced anesthesia versus high inhaled concentration of desflurane combined with remifentanil anesthesia on amplitude of FVEPs. The study is meant to be published in a peer-reviewed journal and might guide the anesthetic regimen for FVEPs. The conclusion is expected to provide high-quality evidence for the effect of desflurane on FVEPs and aim to explore more feasible anesthesia schemes for the clinical application of FVEPs and visual function protection. TRIAL REGISTRATION: This study was registered on clinicaltrials.gov on July 15, 2022. CLINICALTRIALS: gov Identifier: NCT05465330.
Subject(s)
Anesthetics, Inhalation , Desflurane , Evoked Potentials, Visual , Intraoperative Neurophysiological Monitoring , Randomized Controlled Trials as Topic , Remifentanil , Spine , Humans , Desflurane/administration & dosage , Evoked Potentials, Visual/drug effects , Anesthetics, Inhalation/administration & dosage , Prospective Studies , Spine/surgery , Middle Aged , Intraoperative Neurophysiological Monitoring/methods , Adult , Male , Remifentanil/administration & dosage , Female , Propofol/administration & dosage , Young Adult , Aged , Anesthetics, Intravenous/administration & dosage , Adolescent , Time Factors , Orthopedic Procedures , Photic StimulationABSTRACT
The Cambridge Centre for Myelin Repair One (CCMR-One) trial showed that 6 months of bexarotene reduces visual evoked potential (VEP) latency in people with relapsing-remitting multiple sclerosis (MS). In a single-centre follow-up study of these participants, we re-examined full-field VEP and clinical assessments. Twenty participants (12 bexarotene and 8 placebo) were seen on average 27 months after their trial involvement. In an analysis of all eyes with recordable signal (24 bexarotene and 14 placebo), the adjusted bexarotene-placebo treatment difference in P100 latency was -7.79 (95% confidence interval (CI) = -14.76, -0.82) ms, p = 0.044. We conclude that there were durable improvements in VEP latency, suggesting long-term benefits from exposure to a remyelinating drug.
Subject(s)
Bexarotene , Evoked Potentials, Visual , Multiple Sclerosis, Relapsing-Remitting , Humans , Evoked Potentials, Visual/drug effects , Male , Female , Adult , Bexarotene/pharmacology , Follow-Up Studies , Multiple Sclerosis, Relapsing-Remitting/drug therapy , Multiple Sclerosis, Relapsing-Remitting/physiopathology , Middle Aged , Tetrahydronaphthalenes/pharmacology , Tetrahydronaphthalenes/administration & dosage , Treatment Outcome , Double-Blind MethodABSTRACT
Remyelination efficiency declines with advancing age in animal models, but this has been harder to demonstrate in people with multiple sclerosis. We show that bexarotene, a putatively remyelinating retinoid-X receptor agonist, shortened the visual evoked potential latency in patients with chronic optic neuropathy aged under 42 years only (with the effect diminishing by 0.45 ms per year of age); and increased the magnetization transfer ratio of deep gray matter lesions in those under 43 years only. Addressing this age-related decline in human remyelination capacity will be an important step in the development of remyelinating therapies that work across the lifespan.
Subject(s)
Bexarotene , Optic Nerve Diseases , Peripheral Nervous System Agents , Remyelination , Retinoid X Receptors , Age Factors , Aged , Animals , Bexarotene/pharmacology , Bexarotene/therapeutic use , Evoked Potentials, Visual/drug effects , Evoked Potentials, Visual/physiology , Humans , Multiple Sclerosis/complications , Multiple Sclerosis/drug therapy , Multiple Sclerosis/physiopathology , Optic Nerve Diseases/drug therapy , Optic Nerve Diseases/etiology , Optic Nerve Diseases/physiopathology , Peripheral Nervous System Agents/pharmacology , Peripheral Nervous System Agents/therapeutic use , Remyelination/drug effects , Remyelination/physiology , Retinoid X Receptors/administration & dosage , Retinoid X Receptors/agonists , Retinoid X Receptors/pharmacology , Retinoids/administration & dosage , Retinoids/pharmacologyABSTRACT
Clinically, acute ischemic symptoms in the eyes are one of the main causes of vision loss, with the associated inflammatory response and oxidative stress being the key factors that cause injury. Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common type of ischemic optic neuropathy (ION); however, there are still no effective or safe treatment options to date. In this study, we investigated the neuroprotective effects of n-butylidenephthalide (BP) treatment in an experimental NAION rodent model (rAION). BP (10 mg/kg) or PBS (control group) were administered on seven consecutive days in the rAION model. Rats were evaluated for visual function by flash visual evoked potentials (FVEPs) at 4 weeks after NAION induction. The retina and optic nerve were removed for histological examination after the rats were euthanized. The molecular machinery of BP treatment in the rAION model was analyzed using Western blotting. We discovered that BP effectively improves retinal ganglion cell survival rates by preventing apoptotic processes after AION induction and reducing the inflammatory response through which blood-borne macrophages infiltrate the optic nerve. In addition, BP significantly preserved the integrity of the myelin sheath in the rAION model, demonstrating that BP can prevent the development of demyelination. Our immunoblotting results revealed the molecular mechanism through which BP mitigates the neuroinflammatory response through inhibition of the NF-κB signaling pathway. Taken together, these results demonstrate that BP can be used as an exceptional neuroprotective agent for ischemic injury.
Subject(s)
Ischemia/drug therapy , Neuroprotective Agents/pharmacology , Optic Neuropathy, Ischemic/drug therapy , Phthalic Anhydrides/pharmacology , Retinal Ganglion Cells/drug effects , Animals , Apoptosis/drug effects , Disease Models, Animal , Evoked Potentials, Visual/drug effects , Inflammation/drug therapy , Macrophages/drug effects , Male , Optic Nerve/drug effects , Rats , Rats, Wistar , Retina/drug effectsABSTRACT
BACKGROUND: Intraoperative flash visual evoked potential (FVEP) can be used to monitor visual function during spine surgery. However, it is limited due to the previous perception of its sensitivity to inhalation anesthesia. We conducted this trial to test the noninferiority of sevoflurane-propofol-balanced anesthesia (BA) versus popular propofol-based total intravenous anesthesia (TIVA) on the amplitude of FVEP during spine surgery. METHODS: A total of 60 patients undergoing spine surgery were randomized to receive either sevoflurane-propofol-balanced anesthesia (BA group) or propofol-based total intravenous anesthesia (TIVA group) for anesthesia maintenance. We titrated the propofol plasma concentration to keep the bispectral index (BIS) values between 40 and 50. The primary outcome was the P100-N145 amplitudes of FVEP at 120 minutes after induction of anesthesia. The noninferiority margin (δ) was defined as 10% of the P100-N145 amplitude at 120 minutes after induction in the TIVA group. If the confidence interval (CI) for mean differences of P100-N145 amplitude at 120 minutes after induction between BA and TIVA groups lied above the lower limit of -δ with P < .025, we defined BA group was noninferior to TIVA group. RESULTS: Fifty-nine patients were included in the final analysis. The amplitude of P100-N145 at 120 minutes after anesthesia induction in group BA was noninferior to group TIVA (3.8 [1.3] µV vs 3.2 [1.6] µV, -δ = -0.32, mean difference, 0.57, 95% CI, -0.18 to 1.33, P for noninferiority = .015). CONCLUSIONS: The effect of 0.5 minimum alveolar concentration (MAC) of sevoflurane-propofol-balanced anesthesia on the P100-N145 amplitude of FVEP was noninferior to that of propofol-based TIVA under comparable BIS range.
Subject(s)
Evoked Potentials, Visual , Propofol , Sevoflurane , Spine , Anesthetics, Inhalation/pharmacology , Anesthetics, Intravenous/pharmacology , Balanced Anesthesia , Evoked Potentials, Visual/drug effects , Humans , Propofol/pharmacology , Sevoflurane/pharmacology , Spine/surgeryABSTRACT
Regular cannabis using causes vision impairment by affecting human retinal neurotransmission. However, studies less considered its impact on the subsequent visual cortical processing, key feature for the integration of the visual signal in brain. We aimed at investigating this purpose in regular cannabis users using spatial frequencies and temporal frequencies filtered visual stimuli. We recruited 45 regular cannabis users and 25 age-matched controls. We recorded visual evoked potentials during the projection of low spatial frequency (0.5 cycles/degree) or high spatial frequency gratings (15 cycles/degree), which were presented statically (0 Hz) or dynamically (8 Hz). We analyzed the amplitude, latency, and area under the curve of both P100 and N170, best EEG markers for early visual processing. Data were compared between groups by repeated measures ANCOVA. Results showed a significant decrease in P100 amplitude among regular cannabis users in low spatial frequency (F(1,67) = 4.43; p = 0.04) and in dynamic condition (F(1,67) = 4.35; p = 0.04). Analysis also reported a decrease in P100 area under the curve in regular cannabis users to low spatial frequency (F(1,67) = 4.31; p = 0.04) and in dynamic condition (F(1,67) = 7.65; p < 0.01). No effect was found on P100 latency, N170 amplitude, latency, or area under the curve. We found alteration of P100 responses to low spatial frequency and dynamic stimuli in regular cannabis users. This result could be interpreted as a preferential magnocellular impairment where such deficit could be linked to glutamatergic dysfunction. As mentioned in the literature, visual and electrophysiological anomalies in schizophrenia are related to a magnocellular dysfunction. Further studies are needed to clarify electrophysiological deficits in both populations. CLINICAL TRIALS REGISTRATION: Electrophysiological Study of the Functioning of Magnocellular Visual Pathway in Regular Cannabis Users (CAUSA MAP). [NCT02864680; ID 2013-A00097-38]. https://clinicaltrials.gov/ct2/show/NCT02864680?cond=Cannabis&cntry=FR&draw=2&rank=1.
Subject(s)
Brain/drug effects , Cannabis/adverse effects , Evoked Potentials, Visual/drug effects , Visual Perception/drug effects , Adult , Female , Humans , Male , Retina/drug effects , Substance-Related Disorders , Synaptic Transmission/drug effects , Visual Pathways/physiopathologyABSTRACT
Retinal prosthesis is regarded as the treatment for vision restoration in the blind with retinal degeneration (RD) due to the loss of photoreceptors. A strategy for retinal prosthesis is to electrically activate surviving neurons. The retina's response to electrical stimulation in a larger RD model has not been studied yet. Therefore, in this study, we investigated electrically evoked retinal responses in a previously validated N-methyl-N-nitrosourea (MNU)-induced porcine RD model. Electrically evoked responses were evaluated based on the number of retinal ganglion cell (RGC) spikes via multichannel recordings. Stimulation pulses were applied to degenerative and wild-type retinas with pulse modulation. Compared to wild-type retinas, degenerative retinas showed higher threshold values of pulse amplitude and pulse duration. The rate of increase in the number of RGC spikes relative to stimulus intensity was lower in degenerative retinas than in normal retinas. In severely degenerated retinas, few RGCs showed electrically evoked spikes. Our results suggest that the degenerative porcine retina requires a higher charge than the normal porcine retina. In the early stage of RD, it is easier to induce RGC spikes through electrical stimulation using retinal prosthesis; however, when the degeneration is severe, there may be difficulty recovering patient vision.
Subject(s)
Evoked Potentials, Visual/drug effects , Methylnitrosourea/toxicity , Retinal Degeneration , Retinal Ganglion Cells/metabolism , Animals , Disease Models, Animal , Electric Stimulation , Female , Retinal Degeneration/chemically induced , Retinal Degeneration/metabolism , Retinal Degeneration/physiopathology , Swine , Swine, MiniatureABSTRACT
Fish oil is rich in omega-3 fatty acids and essential for neuronal myelination and maturation. The aim of this study was to investigate whether the use of a mixed-lipid emulsion composed of soybean oil, medium-chain triglycerides, olive oil, and fish oil (SMOF-LE) compared to a pure soybean oil-based lipid emulsion (S-LE) for parenteral nutrition had an impact on neuronal conduction in preterm infants. This study is a retrospective matched cohort study comparing preterm infants <1000 g who received SMOF-LE in comparison to S-LE for parenteral nutrition. Visual evoked potentials (VEPs) were assessed longitudinally from birth until discharge. The latencies of the evoked peaks N2 and P2 were analyzed. The analysis included 76 infants (SMOF-LE: n = 41 and S-LE: n = 35) with 344 VEP measurements (SMOF-LE: n= 191 and S-LE n = 153). Values of N2 and P2 were not significantly different between the SMOF-LE and S-LE groups. A possible better treatment effect in the SMOF-LE group was seen as a trend toward a shorter latency, indicating faster neural conduction at around term-equivalent age. Prospective trials and follow-up studies are necessary in order to evaluate the potential positive effect of SMOF-LE on neuronal conduction and visual pathway maturation.
Subject(s)
Evoked Potentials, Visual/drug effects , Fat Emulsions, Intravenous/administration & dosage , Fat Emulsions, Intravenous/chemistry , Fish Oils/administration & dosage , Neural Conduction/drug effects , Female , Humans , Infant, Newborn , Infant, Premature/physiology , Male , Olive Oil/administration & dosage , Parenteral Nutrition , Retrospective Studies , Soybean Oil/administration & dosage , Triglycerides/administration & dosageABSTRACT
Hypoxic-ischemic encephalopathy (HIE) remains to be a major cause of long-term neurodevelopmental deficits in term neonates. Hypothermia offers partial neuroprotection warranting research for additional therapies. Kynurenic acid (KYNA), an endogenous product of tryptophan metabolism, was previously shown to be beneficial in rat HIE models. We sought to determine if the KYNA analog SZR72 would afford neuroprotection in piglets. After severe asphyxia (pHa = 6.83 ± 0.02, ΔBE = -17.6 ± 1.2 mmol/L, mean ± SEM), anesthetized piglets were assigned to vehicle-treated (VEH), SZR72-treated (SZR72), or hypothermia-treated (HT) groups (n = 6, 6, 6; Tcore = 38.5, 38.5, 33.5 °C, respectively). Compared to VEH, serum KYNA levels were elevated, recovery of EEG was faster, and EEG power spectral density values were higher at 24 h in the SZR72 group. However, instantaneous entropy indicating EEG signal complexity, depression of the visual evoked potential (VEP), and the significant neuronal damage observed in the neocortex, the putamen, and the CA1 hippocampal field were similar in these groups. In the caudate nucleus and the CA3 hippocampal field, neuronal damage was even more severe in the SZR72 group. The HT group showed the best preservation of EEG complexity, VEP, and neuronal integrity in all examined brain regions. In summary, SZR72 appears to enhance neuronal activity after asphyxia but does not ameliorate early neuronal damage in this HIE model.
Subject(s)
Asphyxia Neonatorum/drug therapy , Brain Ischemia/drug therapy , Kynurenic Acid/analogs & derivatives , Neurons/metabolism , Animals , Asphyxia Neonatorum/metabolism , Asphyxia Neonatorum/pathology , Brain Ischemia/metabolism , Brain Ischemia/pathology , CA1 Region, Hippocampal/diagnostic imaging , CA1 Region, Hippocampal/drug effects , CA3 Region, Hippocampal/diagnostic imaging , CA3 Region, Hippocampal/drug effects , Disease Models, Animal , Electroencephalography , Evoked Potentials, Visual/drug effects , Humans , Kynurenic Acid/pharmacology , Neurons/drug effects , Neurons/pathology , Rats , Translational Research, BiomedicalABSTRACT
Purpose: Patients that medicate with antidepressants commonly report dryness of eyes. The cause is often attributed to the anticholinergic properties of the drugs. However, regulation of tear production includes a substantial reflex-evoked component and is regulated via distinct centers in the brain. Further, the anticholinergic component varies greatly among antidepressants with different mechanisms of action. In the current study it was wondered if acute administration of antidepressants can disturb production of tears by affecting the afferent and/or central pathway. Methods: Tear production was examined in vivo in anesthetized rats in the presence or absence of the tricyclic antidepressant (TCA) clomipramine or the selective serotonin reuptake inhibitor (SSRI) escitalopram. The reflex-evoked production of tears was measured by challenging the surface of the eye with menthol (0.1 mM) and cholinergic regulation was examined by intravenous injection with the nonselective muscarinic agonist methacholine (1-5 µg/kg). Results: Acute administration of clomipramine significantly attenuated both reflex-evoked and methacholine-induced tear production. However, escitalopram only attenuated reflex-evoked tear production, while methacholine-induced production of tears remained unaffected. Conclusions: This study shows that antidepressants with different mechanisms of action can impair tear production by attenuating reflex-evoked signaling. Further, antimuscarinic actions are verified as a likely cause of lacrimal gland hyposecretion in regard to clomipramine but not escitalopram. Future studies on antidepressants with different selectivity profiles and mechanisms of action are required to further elucidate the mechanisms by which antidepressants affect tear production.
Subject(s)
Citalopram/pharmacology , Clomipramine/pharmacology , Dry Eye Syndromes , Evoked Potentials, Visual , Lacrimal Apparatus , Tears/physiology , Animals , Antidepressive Agents/pharmacology , Cholinergic Antagonists/pharmacology , Dry Eye Syndromes/chemically induced , Dry Eye Syndromes/physiopathology , Evoked Potentials, Visual/drug effects , Evoked Potentials, Visual/physiology , Lacrimal Apparatus/drug effects , Lacrimal Apparatus/physiology , Methacholine Chloride/pharmacology , Miotics/pharmacology , RatsABSTRACT
OBJECTIVE: To investigate potential neuroprotective and pro-remyelinating effects of alemtuzumab in multiple sclerosis (MS), using the visual pathway as a model. METHODS: We monitored clinical, multifocal visual evoked potential (mfVEP) and MRI outcomes in 30 patients commencing alemtuzumab for relapsing MS, and a reference group of 20 healthy controls (HCs), over 24 months. Change in mfVEP latency was the primary endpoint; change in optic radiation (OR) lesion diffusion metrics and Mars letter contrast sensitivity over the course of the study were secondary endpoints. RESULTS: In patients, we observed a mean shortening of mfVEP latency of 1.21 ms over the course of the study (95% CI 0.21 to 2.21, p=0.013), not altered by correction for age, gender, disease duration or change in OR T2 lesion volume. Mean mfVEP latency in the HC group increased over the course of the study by 0.72 ms (not significant). Analysis of chronic OR T2 lesions (patients) showed an increase in normalised fractional anisotropy and axial diffusivity between baseline and 24 months (both p<0.01). Mean Mars letter contrast sensitivity was improved at 24 months vs baseline (p<0.001), and driven by an early improvement, in both patients and HC. CONCLUSION: We found evidence of partial lesion remyelination after alemtuzumab therapy, indicating either natural restoration in the context of a 'permissive' local milieu; or potentially an independent, pro-reparative mechanism of action. The visual system presents a unique opportunity to study function-structure specific effects of therapy and inform the design of future phase 2 MS remyelination trials.
Subject(s)
Alemtuzumab/therapeutic use , Brain/diagnostic imaging , Evoked Potentials, Visual/physiology , Immunologic Factors/therapeutic use , Multiple Sclerosis/diagnostic imaging , Visual Pathways/diagnostic imaging , Adult , Alemtuzumab/pharmacology , Brain/drug effects , Evoked Potentials, Visual/drug effects , Female , Humans , Immunologic Factors/pharmacology , Magnetic Resonance Imaging , Male , Middle Aged , Multiple Sclerosis/drug therapy , Neurologic Examination , Visual Pathways/drug effects , Young AdultABSTRACT
Several lines of research suggest that impairments in long-term potentiation (LTP)-like synaptic plasticity might be a key pathophysiological mechanism in schizophrenia (SZ) and bipolar disorder type I (BDI) and II (BDII). Using modulations of visually evoked potentials (VEP) of the electroencephalogram, impaired LTP-like visual cortical plasticity has been implicated in patients with BDII, while there has been conflicting evidence in SZ, a lack of research in BDI, and mixed results regarding associations with symptom severity, mood states, and medication. We measured the VEP of patients with SZ spectrum disorders (n = 31), BDI (n = 34), BDII (n = 33), and other BD spectrum disorders (n = 2), and age-matched healthy control (HC) participants (n = 200) before and after prolonged visual stimulation. Compared to HCs, modulation of VEP component N1b, but not C1 or P1, was impaired both in patients within the SZ spectrum (χâ2 = 35.1, P = 3.1 × 10-9) and BD spectrum (χâ2 = 7.0, P = 8.2 × 10-3), including BDI (χâ2 = 6.4, P = .012), but not BDII (χâ2 = 2.2, P = .14). N1b modulation was also more severely impaired in SZ spectrum than BD spectrum patients (χâ2 = 14.2, P = 1.7 × 10-4). N1b modulation was not significantly associated with Positive and Negative Syndrome Scale (PANSS) negative or positive symptoms scores, number of psychotic episodes, Montgomery and Åsberg Depression Rating Scale (MADRS) scores, or Young Mania Rating Scale (YMRS) scores after multiple comparison correction, although a nominal association was observed between N1b modulation and PANSS negative symptoms scores among SZ spectrum patients. These results suggest that LTP-like plasticity is impaired in SZ and BD. Adding to previous genetic, pharmacological, and electrophysiological evidence, these results implicate aberrant synaptic plasticity as a mechanism underlying SZ and BD.
Subject(s)
Bipolar Disorder/physiopathology , Cyclothymic Disorder/physiopathology , Evoked Potentials, Visual/physiology , Neuronal Plasticity/physiology , Psychotic Disorders/physiopathology , Schizophrenia/physiopathology , Visual Cortex/physiopathology , Adolescent , Adult , Aged , Anticonvulsants/pharmacology , Antipsychotic Agents/pharmacology , Bipolar Disorder/drug therapy , Cyclothymic Disorder/drug therapy , Electroencephalography , Evoked Potentials, Visual/drug effects , Female , Humans , Male , Middle Aged , Neuronal Plasticity/drug effects , Psychotic Disorders/drug therapy , Schizophrenia/drug therapy , Visual Cortex/drug effects , Young AdultABSTRACT
Microglia activation and release of pro-inflammatory cytokines have been closely linked to glaucoma. However, the mechanisms that initiate these pathways remain unclear. Here, we investigated the role of a pro-inflammatory cytokine--osteopontin (OPN), in retinal microglia activation process along with the underlying mechanisms in glaucoma. A rat chronic ocular hypertension (COH) model was established presenting an increase in retinal OPN level and activation of microglia. Primary microglia cells were isolated and cultured under a pressure culture system showing heightened expressions of microglia-derived OPN with changes in inflammatory factors (TNF-α, IL-1ß, and IL-6). OPN and OPN neutralizing antibody (Anti-OPN) interventions were both applied systems for comparison, and cross-referenced with OPN knockdown in vitro. JAK/STAT, NF-κB, ERK1/2, and p38 MAPK, recognized as the primary signaling pathways related to microglia activation, were then screened on whether they can facilitate OPN to act on microglia and their impact on specific inhibitors. Thereafter, retrograde labeling of retinal ganglion cells (RGCs) and flash visual evoked potentials (F-VEP) were used to investigate neuron protection in context of each blockade. Results suggest that OPN is able to enhance the proliferation and activation of retinal microglia in experimental glaucoma which may play a role in the glaucomatous optic neuropathy, and contribute to the eventual RGCs loss and vision function impairment. Such effect may be mediated through the regulation of p38 MAPK signaling pathway.
Subject(s)
Glaucoma/drug therapy , Ocular Hypertension/etiology , Osteopontin/pharmacology , Retinal Ganglion Cells/drug effects , p38 Mitogen-Activated Protein Kinases/metabolism , Animals , Cytokines/metabolism , Disease Models, Animal , Evoked Potentials, Visual/drug effects , Evoked Potentials, Visual/physiology , Glaucoma/metabolism , Male , Microglia/drug effects , Microglia/metabolism , Ocular Hypertension/metabolism , Osteopontin/metabolism , Rats, Sprague-Dawley , Retina/metabolism , Retinal Ganglion Cells/metabolism , Tumor Necrosis Factor-alpha/metabolismABSTRACT
AIMS: To evaluate incidence of toxic optic neuropathy in patients receiving ethambutol (EMB) for 6 months and to identify its early indicators. METHODS: We included 50 patients on anti-tubercular therapy (ATT) including EMB (HRE regimen) based on total body weight for 6 months. Best-corrected visual acuity (ETDRS), colour vision (Ishihara pseudo-isochromatic plates), contrast sensitivity (Pelli-Robson chart), Humphrey visual field analysis (HVF 30-2 SITA FAST), pattern visual evoked response (VER) and spectral-domain optical coherence tomography (SDOCT) for ganglion cell inner plexiform layer (GCIPL) and retinal nerve fibre layer (RNFL) analysis were assessed at baseline and at 2, 4 and 6 months after starting ATT. RESULTS: Mean age of the patients was 36.5±14.7 years with male:female ratio of 2.5:1. Mean daily dosage of EMB was 17.5±1.3 mg/kg/day. No significant change was observed in visual acuity, contrast sensitivity, color vision and mean or pattern SD on HVF at 6 months. Significant increase in VER latency of >2 SD (>125 ms) was observed in 46% eyes on follow-up indicating subclinical toxicity. Significant loss of mean RNFL (from 100.79±16.05 µm to 89.96±13.79 µm) and GCIPL thickness (from 83.1±5.60 µm to 79.85±6.45 µm) was observed at 6 months (p=0.001 for both). Patients with subclinical toxicity had significantly greater damage in temporal RNFL quadrant, supero-nasal and infero-nasal GCIPL sectors compared with others. CONCLUSION: The incidence of clinical EMB optic neuropathy was <2%, though subclinical damage in the form of increase in VER latency, and decrease in RNFL and GCIPL on OCT was seen in 46% eyes.
Subject(s)
Antitubercular Agents/toxicity , Ethambutol/toxicity , Optic Nerve Diseases/chemically induced , Optic Nerve/drug effects , Adult , Aged , Color Vision/physiology , Contrast Sensitivity/physiology , Evoked Potentials, Visual/drug effects , Evoked Potentials, Visual/physiology , Female , Humans , Incidence , Male , Middle Aged , Nerve Fibers/pathology , Optic Nerve Diseases/diagnosis , Optic Nerve Diseases/epidemiology , Prospective Studies , Retinal Ganglion Cells/pathology , Tomography, Optical Coherence , Visual Acuity/physiology , Visual Fields/physiology , Young AdultABSTRACT
PURPOSE: To study the ability of pattern reversal visual evoked potentials (VEPs) to detect subclinical visual pathway pathologic assessment in Behcet disease (BD) and correlate VEP results in BD with disease activity and response to corticosteroid treatment. METHODS: This study included 18 patients (36 eyes) with BD without recent ocular manifestations and 20 healthy controls (40 eyes). Clinical history was taken, and clinical examinations were done. Visual evoked potential recordings were performed by an electromyographic evoked machine for patients and controls. Corticosteroids were given to patients with extraocular activity, and VEP was repeated after clinical and laboratory improvement of the manifestations. RESULTS: p100 latency of VEP was prolonged in 8 patients (11 eyes) (44.4% of cases). Mean p100 latency showed statistically significant prolongations in BD group compared with the control group (106.7 ± 8.1 ms vs. 99.6 ± 1.9 ms) with P value < 0.001. There was a positive correlation between p100 latency and the disease activity score (r = 0.8673), whereas there was no correlation between p100 latency and the disease duration (r = 0.00072). Patients treated with corticosteroids showed statistically significant reduction in mean p100 latency after treatment (P < 0.001). CONCLUSIONS: Visual evoked potential may be a valuable tool for detecting subclinical neurologic affection in BD.
Subject(s)
Behcet Syndrome/diagnosis , Behcet Syndrome/physiopathology , Evoked Potentials, Visual/drug effects , Evoked Potentials, Visual/physiology , Adrenal Cortex Hormones/therapeutic use , Adult , Behcet Syndrome/diet therapy , Female , Humans , Male , Middle Aged , Prednisolone/therapeutic use , Visual Pathways/pathologyABSTRACT
Visual deficits are among the most prevalent symptoms in patients with multiple sclerosis (MS). To understand deficits in the visual pathway during MS and potential treatment effects, we used experimental autoimmune encephalomyelitis (EAE), the most commonly used animal model of MS. The afferent visual pathway was assessed in vivo using optical coherence tomography (OCT), electroretinography (ERG), and visually evoked cortical potentials (VEPs). Inflammation, demyelination, and neurodegeneration were examined by immunohistochemistry ex vivo. In addition, an immunomodulatory, remyelinating agent, the estrogen receptor ß ligand chloroindazole (IndCl), was tested for its therapeutic potential in the visual pathway. EAE produced functional deficits in visual system electrophysiology, including suppression of ERG and VEP waveform amplitudes and increased signal latencies. Therapeutic IndCl rescued overall visual system latency by VEP but had little impact on amplitude or ERG findings relative to vehicle. Faster VEP conduction in IndCl-treated mice was associated with enhanced myelin basic protein signal in all visual system structures examined. IndCl preserved retinal ganglion cells (RGCs) and oligodendrocyte density in the prechiasmatic white matter, but similar retinal nerve fiber layer thinning by OCT was noted in vehicle and IndCl-treated mice. Although IndCl differentially attenuated leukocyte and astrocyte staining signal throughout the structures analyzed, axolemmal varicosities were observed in all visual fiber tracts of mice with EAE irrespective of treatment, suggesting impaired axonal energy homeostasis. These data support incomplete functional recovery of VEP amplitude with IndCl, as fiber tracts displayed persistent axon pathology despite remyelination-induced decreases in latencies, evidenced by reduced optic nerve g-ratio in IndCl-treated mice. Although additional studies are required, these findings demonstrate the dynamics of visual pathway dysfunction and disability during EAE, along with the importance of early treatment to mitigate EAE-induced axon damage.
Subject(s)
Azo Compounds/pharmacology , Encephalomyelitis, Autoimmune, Experimental/pathology , Naphthalenes/pharmacology , Remyelination/drug effects , Visual Pathways/drug effects , Visual Pathways/pathology , Animals , Evoked Potentials, Visual/drug effects , Inflammation/pathology , Mice , Mice, Inbred C57BL , Multiple Sclerosis , Nerve Degeneration/pathologyABSTRACT
PURPOSE: Acute focal demyelination is the characteristic feature of multiple sclerosis, with the majority of damaged axons undergoing limited remyelination and forming chronic lesions. Potential remyelinating agents are currently under development and there is therefore an urgent need for reliable in vivo biomarkers of remyelination. This study aimed to investigate potential changes in multifocal visual evoked potentials' (mfVEPs) latency in a cohort of relapsing-remitting multiple sclerosis (RRMS) patients. The potential sample size required for a remyelination-based clinical trial using different treatment effect sizes and the mfVEP latency as an outcome measure was also estimated. METHODS: A total of 50 RRMS consecutive patients with no previous history of optic neuritis in at least one eye and 15 normal controls of similar age and gender composition were prospectively enrolled. Fifteen patients had a history of unilateral ON more than 12 months earlier, whereas 41 patients demonstrated optic radiations lesions on MRI at baseline. Most patients were on disease modifying therapy. A mfVEP was recorded at baseline and 12 months later. RESULTS: At baseline, the mfVEP latency in RRMS patients was delayed compared with normal controls in both optic neuritis and nonoptic neuritis eyes. Latency delay was significantly correlated to optic radiation lesion volume (R2 = 0.38, P < 0.001). There was no significant latency change in multiple sclerosis patients' eyes or optic neuritis and nonoptic neuritis eyes over the follow-up period with latency remaining remarkably constant. This was despite the fact that 46 of 50 patients were on disease-modifying therapies, implying current treatments do not affect myelination in chronic RRMS cases. Sample size calculations to evaluate an additional or alternative remyelinating agent, based on a 40% treatment effect, revealed that a relatively small sample size (78 patients) would be required to demonstrate efficacy in future trials of remyelination therapies. CONCLUSIONS: Given its known sensitivity for latency changes and the stability found in this RRMS population, the mfVEP represents an ideal biomarker to assess the degree of latency recovery that may be achieved by remyelination in multiple sclerosis.
Subject(s)
Evoked Potentials, Visual/physiology , Multiple Sclerosis, Relapsing-Remitting/physiopathology , Adult , Antirheumatic Agents/therapeutic use , Clinical Trials as Topic , Evoked Potentials, Visual/drug effects , Humans , Male , Middle Aged , Multiple Sclerosis, Relapsing-Remitting/complications , Multiple Sclerosis, Relapsing-Remitting/drug therapy , Optic Neuritis/etiologyABSTRACT
Traumatic optic neuropathy is sinister sequelae of craniofacial trauma leading to vision loss. The decision between early medical or surgical intervention is usually individualised. Visual evoked potentials may guide the treatment plan. We describe a young male presenting 5 days after a road traffic accident with no perception of light vision in the right eye. He was managed medically with high dose of intravenous steroids. At the 3-month follow-up, he reported a reversal of vision loss with return of visual acuity to 3/60, which improved to 6/36 at 5 months and remained stable at 8 months.
Subject(s)
Accidents, Traffic , Blindness/drug therapy , Methylprednisolone/administration & dosage , Optic Nerve Injuries/drug therapy , Orbital Fractures/complications , Administration, Intravenous , Adolescent , Blindness/diagnosis , Blindness/etiology , Evoked Potentials, Visual/drug effects , Humans , Male , Optic Nerve/diagnostic imaging , Optic Nerve/drug effects , Optic Nerve Injuries/diagnosis , Optic Nerve Injuries/etiology , Orbit/diagnostic imaging , Orbit/innervation , Orbital Fractures/diagnosis , Tomography, Optical Coherence , Tomography, X-Ray Computed , Treatment Outcome , Visual Acuity/drug effectsABSTRACT
Hypoxic-ischemic encephalopathy (HIE) is still a major cause of neonatal death and disability as therapeutic hypothermia (TH) alone cannot afford sufficient neuroprotection. The present study investigated whether ventilation with molecular hydrogen (2.1% H2) or graded restoration of normocapnia with CO2 for 4 h after asphyxia would augment the neuroprotective effect of TH in a subacute (48 h) HIE piglet model. Piglets were randomized to untreated naïve, control-normothermia, asphyxia-normothermia (20-min 4%O2-20%CO2 ventilation; Tcore = 38.5 °C), asphyxia-hypothermia (A-HT, Tcore = 33.5 °C, 2-36 h post-asphyxia), A-HT + H2, or A-HT + CO2 treatment groups. Asphyxia elicited severe hypoxia (pO2 = 19 ± 5 mmHg) and mixed acidosis (pH = 6.79 ± 0.10). HIE development was confirmed by altered cerebral electrical activity and neuropathology. TH was significantly neuroprotective in the caudate nucleus but demonstrated virtually no such effect in the hippocampus. The mRNA levels of apoptosis-inducing factor and caspase-3 showed a ~10-fold increase in the A-HT group compared to naïve animals in the hippocampus but not in the caudate nucleus coinciding with the region-specific neuroprotective effect of TH. H2 or CO2 did not augment TH-induced neuroprotection in any brain areas; rather, CO2 even abolished the neuroprotective effect of TH in the caudate nucleus. In conclusion, the present findings do not support the use of these medical gases to supplement TH in HIE management.