Histological and Top-Down Proteomic Analyses of the Visual Pathway in the Cuprizone Demyelination Model

A change in visual perception is a frequent early symptom of multiple sclerosis (MS), the pathoaetiology of which remains unclear. Following a slow demyelination process caused by 12 weeks of low-dose (0.1%) cuprizone (CPZ) consumption, histology and proteomics were used to investigate components of the visual pathway in young adult mice. Histological investigation did not identify demyelination or gliosis in the optic tracts, pretectal nuclei, superior colliculi, lateral geniculate nuclei or visual cortices. However, top-down proteomic assessment of the optic nerve/tract revealed a significant change in the abundance of 34 spots in high-resolution two-dimensional (2D) gels. Subsequent liquid chromatography-tandem mass spectrometry (LC-TMS) analysis identified alterations in 75 proteoforms. Literature mining revealed the relevance of these proteoforms in terms of proteins previously implicated in animal models, eye diseases and human MS. Importantly, 24 proteoforms were not previously described in any animal models of MS, eye diseases or MS itself. Bioinformatic analysis indicated involvement of these proteoforms in cytoskeleton organization, metabolic dysregulation, protein aggregation and axonal support. Collectively, these results indicate that continuous CPZ-feeding, which evokes a slow demyelination, results in proteomic changes that precede any clear histological changes in the visual pathway and that these proteoforms may be potential early markers of degenerative demyelinating conditions.

Posterior ischemic optic neuropathy following a major burn injury and review of the literature

Posterior ischemic optic neuropathy following burns is a rare but devastating condition that can result in total bilateral visual loss. Numerous treatment modalities have been trialed, yet there is no effective therapy to delay or reverse the disease. Hence, it is imperative for burns surgeons to be aware of the potential risk factors and have a high index of suspicion right from the outset to prevent this outcome. Here, we discuss the case of a patient that developed posterior ischemic optic neuropathy subsequent to a major burn injury. We also present a literature review on optic neuropathies following burns to describe the etiology, clinical signs, and potential management.

No Evidence of Varicella-Zoster Virus Infection in Temporal Artery Biopsies of Anterior Ischemic Optic Neuropathy Patients With and Without Giant Cell Arteritis

Background

To test the hypothesis that varicella-zoster virus (VZV) infection contributes to temporal arteritis pathogenesis, comprehensive in situ analysis was performed on temporal artery biopsies of 38 anterior ischemic optic neuropathy (AION) patients, including 14 (37%) with giant cell arteritis.

Methods

Biopsies were completely sectioned, and, on average, 146 serial sections per patient were stained for VZV glycoprotein E.

Results

Four of 38 AION patients showed VZV glycoprotein E staining, but VZV infection was not confirmed by staining for VZV IE63 protein and VZV-specific polymerase chain reaction on adjacent sections.

Conclusions

This study refutes the premise that VZV is casually related to AION with and without giant cell arteritis.

Non-Arteritic Anterior Ischaemic Optic Neuropathy Associated with Optic Nerve Hypoplasia and Elevated Intraocular Pressure

A 46-year-old woman with no known past medical history presented with sudden painless visual impairment in the left eye. Ocular examination showed a swollen and hyperaemic left optic disc with a small and crowded right optic disc. Intraocular pressures were moderately elevated. Investigations for underlying ischaemic and inflammatory markers were normal. A diagnosis of left non-arteritic anterior ischaemic optic neuropathy (NAAION) was made, with associated ocular hypertension. On follow-up, NAAION resolved with anti-glaucoma medication and repeat fundus examination confirmed the presence of an underlying hypoplastic disc. The coexistence of optic disc hypoplasia and elevated intraocular pressure may further augment the risk of developing NAAION.

Waking Up Blind in the ICU: A Case Report of Ischemic Optic Neuropathy in a Burn Patient

The objective of this report is to analyze and summarize the current literature of ischemic optic neuropathy (ION), a rare complication in severe burn and trauma victims, while presenting an urban burn center's experience with the condition. This is an unfortunate condition and this report will raise awareness to a potential complication in the burn patient population as well as in critically ill patients in other settings.

We present the case of a 27-year-old healthy male patient admitted to our Burn Center with 85% total body surface area (TBSA) full-thickness burns sustained in a house fire. The patient had a complicated hospital course but improved over time and was weaned off of prolonged ventilation and sedation. Subsequently, he complained of bilateral blindness. A fundoscopic examination demonstrated bilateral pale optic nerves with sparing of the remaining peripheral retina consistent with ION. The patient suffered complete bilateral vision loss. He had multiple factors that could have instigated the development of ION, including several episodes of septicemia, hypovolemic shock and severe adult respiratory distress syndrome (ARDS) with refractory hypoxemia requiring a prolong ventilation support and vasopressor therapy. 

Due to the advancement of the treatment of acute burns, the survival rate of patients that once would have succumbed to their burn injury, is increasing. With these new achievements, we are facing new challenges and complications. ION has a significant impact on the quality of the patient’s life. The early diagnosis will not necessarily translate into a benefit for these patients as no treatment has been proven successful. Extensive retrospective and prospective studies are necessary to identify and treat this patient population.

Human Optic Nerve: An Enhanced Proteomic Expression Profile

Ophthalmology and visual health are new frontiers for postgenomic research and technologies such as proteomics. In this context, the optic nerve and retina extend as the outgrowth of the brain, wherein the latter receives the optical input and the former relays the information for processing. While efforts to understand the optic nerve proteome have been made earlier, there exists a lacuna in its biochemical composition and molecular functions. We report, in this study, a high-resolution mass spectrometry-based approach using an Orbitrap Fusion Tribrid mass spectrometer to elucidate the human optic nerve proteomic profile. Raw spectra were searched against NCBI Human RefSeq 75 database using SEQUEST HT and MASCOT algorithms. We identified nearly 35,000 peptides in human optic nerve samples, corresponding to 5682 proteins, of which 3222 proteins are being reported for the first time. Label-free quantification using spectral abundance pointed out to neuronal structural proteins such as myelin basic protein, glial fibrillary acidic protein, and proteolipid protein 1 as the most abundant proteins. We also identified several neurotransmitter receptors and postsynaptic density synaptosomal scaffold proteins. Pathway analysis revealed that a majority of the proteins are structural proteins and have catalytic and binding activity. This study is one of the largest proteomic profiles of the human optic nerve and offers the research community an initial baseline optic nerve proteome for further studies. This will also help understand the protein dynamics of the human optic nerve under normal conditions.

A case series: bilateral ischemic optic neuropathy secondary to large volume fluid resuscitation in critically ill burn patients

Ischemic optic neuropathy (ION) in the trauma setting is a rare and devastating condition associated with systemic hypotension, massive volume resuscitation, and sepsis. The objective of this case series is to highlight a potential correlation between severe burn and ischemic optic neuropathy. We present three patients with total body surface area (TBSA) thermal injury burns ranging from 57 to 68% treated at the North Carolina Jaycee Burn Center that developed bilateral ischemic optic neuropathy during their hospital stay. Each patient required greater than 25 L of crystalloid fluid within 24 h after admission, suffered multiple bouts of sepsis, and required extended pressor support. We postulate that ischemic optic neuropathy develops as a result of the interplay between the patient's systemic pathophysiology, i.e. shock, sepsis and the continued need for large volume fluid resuscitation. Current treatments of ION have not proven to be effective, except for possibly limiting fluid resuscitation. In the few cases of refractory burn shock, the incidence of this condition is unlikely to be readily improved. However, it is important for clinicians to be aware of this devastating complication and consider early ophthalmology involvement in the care of severely burned patients.

Retinal ganglion cell (RGC) programmed necrosis contributes to ischemia-reperfusion-induced retinal damage

Retinal ischemia-reperfusion (IR) injury remains a common cause of blindness and has a final pathway of retinal ganglion cell (RGC) death by apoptosis and necrosis. RGC apoptosis was intensively studied in IR injury, while RGC necrosis did not receive nearly enough consideration since it was viewed as an accidental and unregulated cellular event. However, there is evidence that necrosis, like apoptosis, can be implemented by a programmed mechanism. In this study, we tested the role of RGC programmed necrosis (necroptosis) in IR-induced retinal injury. We employed the mouse model of retinal IR injury for in vivo experiments. The oxygen and glucose deprivation (OGD) model was used as an IR model in vitro. Primary RGCs were isolated by an immunopanning technique. Necrostatin 1 (Nec1) was used to inhibit necroptosis in in vitro and in vivo experiments. The changes in gene expression were assessed by quantitative RT-PCR. The distribution of proteins in the retina and in RGC cultures was evaluated by immunohistochemistry and immunocytochemistry, respectively. Our data suggest that proteins (Ripk1 and Ripk3), which initiate necroptosis, were present in normal and ischemic RGCs. Treatment with Nec1 significantly reduced retinal damage after IR. Increased RGC survival and reduced RGC necrosis following OGD were observed in Nec1-treated cultures. We found significantly reduced expression of genes coding pro-inflammatory markers Il1b, Ccl5, Cxcl10, Nos2 and Cybb in Nec1-treated ischemic retinas. Thus, our findings suggest that RGC necroptosis contributes to retinal damage after IR through direct loss of cells and induction of associated inflammatory responses.

Blood pressure treatment in acute ischemic stroke: a review of studies and recommendations

PURPOSE OF REVIEW

Elevated blood pressure (BP) is frequent in patients with acute ischemic stroke. Pathophysiological data support its usefulness to maintain adequate perfusion of the ischemic penumba. This review article aims to summarize the available evidence from clinical studies that examined the prognostic role of BP during the acute phase of ischemic stroke and intervention studies that assessed the efficacy of active BP alteration.

RECENT FINDINGS

We found 34 observational studies (33,470 patients), with results being inconsistent among the studies; most studies reported a negative association between increased levels of BP and clinical outcome, whereas a few studies showed clinical improvement with higher BP levels, clinical deterioration with decreased BP, or no association at all. Similarly, the conclusions drawn by the 18 intervention studies included in this review (1637 patients) were also heterogeneous. Very recent clinical data suggest a possible beneficial effect of early treatment with some antihypertensives on late clinical outcome.

SUMMARY

Observational and interventional studies of management of acute poststroke hypertension yield conflicting results. We discuss different explanations that may account for this and discuss the current guidelines and pathophysiological considerations for the management of acute poststroke hypertension.