The Intrinsic Caspase Death Pathway in Stroke Neurodegeneration

Stroke has been a major source of morbidity and mortality for centuries. Eight-five percent of all strokes are ischemic in nature, meaning they are caused by the occlusion of a major cerebral artery. Despite extensive research to develop effective treatments for ischemic stroke, therapeutic options remain limited. Apoptosis (also termed "programmed cell death") is a process by which a stressed or damaged cell commits "suicide". In stroke, runaway apoptosis contributes to stroke neurodegeneration and neurological decline for days to weeks after disease onset. Cysteine-ASPartic proteASEs (caspases) are key mediators of apoptosis that are activated in distinct molecular pathways, but their impact in stroke is poorly defined. Direct evidence for caspase activation in stroke and the functional relevance of this activity has not been previously characterized. For this dissertation, we developed an unbiased technique for in vivo trapping of active caspases in rodent models of ischemic stroke. We isolated active caspase-9 as a principal contributor to ischemic neurodegeneration in rodents (Rattus norvegicus and Mus musculus). Caspase-9 is the initiator caspase for the intrinsic cell death pathway. Intranasal delivery of a novel, cell membrane-penetrating inhibitor for caspase-9 confirmed the pathogenic relevance of caspase-9 activity in stroke. Caspase-9 inhibition provided neurofunctional protection and established caspase-6 as its downstream target. Caspase-6 is an effector caspase and a member of the intrinsic death pathway that has never been implicated in stroke until now. Coincidentally, we discovered that caspase-6 is specifically activated within the axonal compartment. The temporal and spatial pattern of activation demonstrates that neuronal caspase-9 activity induces caspase-6 activation, which mediates axonal loss in the early stages of stroke (+/- 24 hours). We developed a novel inhibitor for caspase-6, based on a catalytically inactive clone, which demonstrated neuroprotective and axoprotective efficacy against ischemia. Collectively, these results assert that selective inhibition of caspase-9 and caspase-6 is an effective translational strategy for stroke. The impact of caspase activity is not restricted to neuronal death, as caspases can exacerbate inflammation and alter glial function. Thus, caspases are logical therapeutic targets for stroke. However, they have never been clinically evaluated due to a paucity of ideal drug candidates. This dissertation outlines fresh insights into the mechanisms of stroke neurodegeneration and offers novel caspase-based therapeutic strategies for clinical evaluation

Transshipment Problem and Its Variants: A Review

The transshipment problem is a unique Linear Programming Problem (LLP) in that it considers the assumption that all sources and sinks can both receive and distribute shipments at the same time (function in both directions). Being an extension of the classical transportation problem, the transshipment problem covers a wide range of scenarios for logistics and/or transportation inputs and products and offers optimum alternatives for same. In this work the review of literatures from the origin and current trends on the transshipment problem were carried out. This was done in view of the unique managerial needs and formulation of models/objective functions. It was revealed that the LLP offers a wide range of decision alternative for the operations manager based on the dynamic and challenging nature of logistics management. Key words: Transshipment problem, Linear Programming Problems (LPP), model, objective functions, decision alternative

Freedom of Information Act 2011 and Press Freedom: Challenges and Prospects for Media Practice in Nigeria

Information flow is not just a fundamental ingredient of democracy but also a sine qua none to the overall development of the society. Journalism plays an important role in ensuring that relevant information of significance is gathered, processed and transmitted to the citizenry. This paper hinged on access to and transmission of information. Specifically, it examined the Freedom of Information Act, 2011 and press freedom vis-a-vis their implications for journalism practice in Nigeria. The paper is a product of descriptive research and document analysis. Findings revealed that Nigeria’s Freedom of Information Act was not enacted exclusively to aid journalism practice, rather for use by the generality of Nigerians. However, if the applicable aspect of Act is properly harnessed by journalists, the contents of Nigerian mass media would be enriched. It is therefore recommended that the Nigerian Press Council should sponsor a bill in the National Assembly for the enactment of Journalism Practice Act in order to enhance professionalism and efficiency in journalism practice. Again, Nigerian journalists should not over-rely on the assurances of the Act as they are nothing far from façade, rather journalists should keep engaging in investigative journalism so as to publish the real truth not what public officers call the truth

Caspase-9 mediates synaptic plasticity and memory deficits of Danish dementia knock-in mice: caspase-9 inhibition provides therapeutic protection

Background: Mutations in either Aβ Precursor protein (APP) or genes that regulate APP processing, such as BRI2/ITM2B and PSEN1/PSEN2, cause familial dementias. Although dementias due to APP/PSEN1/PSEN2 mutations are classified as familial Alzheimer disease (FAD) and those due to mutations in BRI2/ITM2B as British and Danish dementias (FBD, FDD), data suggest that these diseases have a common pathogenesis involving toxic APP metabolites. It was previously shown that FAD mutations in APP and PSENs promote activation of caspases leading to the hypothesis that aberrant caspase activation could participate in AD pathogenesis. Results: Here, we tested whether a similar mechanism applies to the Danish BRI2/ITM2B mutation. We have generated a genetically congruous mouse model of FDD, called FDDKI, which presents memory and synaptic plasticity deficits. We found that caspase-9 is activated in hippocampal synaptic fractions of FDDKI mice and inhibition of caspase-9 activity rescues both synaptic plasticity and memory deficits. Conclusion: These data directly implicate caspase-9 in the pathogenesis of Danish dementia and suggest that reducing caspase-9 activity is a valid therapeutic approach to treating human dementias

Intranasal Delivery of Caspase-9 Inhibitor Reduces Caspase-6-Dependent Axon/Neuron Loss and Improves Neurological Function after Stroke

Despite extensive research to develop an effective neuroprotective strategy for the treatment of ischemic stroke, therapeutic options remain limited. Although caspase-dependent death is thought to play a prominent role in neuronal injury, direct evidence of active initiator caspases in stroke and the functional relevance of this activity have not previously been shown. Using an unbiased caspase-trapping technique in vivo, we isolated active caspase-9 from ischemic rat brain within 1 h of reperfusion. Pathogenic relevance of active caspase-9 was shown by intranasal delivery of a novel cell membrane-penetrating highly specific inhibitor for active caspase-9 at 4 h postreperfusion (hpr). Caspase-9 inhibition provided neurofunctional protection and established caspase-6 as its downstream target. The temporal and spatial pattern of expression demonstrates that neuronal caspase-9 activity induces caspase-6 activation, mediating axonal loss by 12 hpr followed by neuronal death within 24 hpr. Collectively, these results support selective inhibition of these specific caspases as an effective therapeutic strategy for stroke.C.M.T.wassupported bythe American Heart Association and National Institutes of Health (NIH)GrantsNS035933 and NS43089. G.S.S. and S.J.S. were supported by NIH Grant CA69381. E.S.C. was supported by NIH Grant NS40409.Peer reviewe

Mechanisms of neuronal death in disease: defining the models and the players

Dysregulation of life and death at the cellular level leads to a variety of diseases. In the nervous system, aberrant neuronal death is an outstanding feature of neurodegenerative diseases. Since the discovery of the caspase family of proteases, much effort has been made to determine how caspases function in disease, including neurodegenerative diseases. Although many papers have been published examining caspases in neuronal death and disease, the pathways have not been fully clarified. In the present review, we examine the potential players in the death pathways, the current tools for examining these players and the models for studying neurological disease. Alzheimer's disease, the most common neurodegenerative disorder, and cerebral ischaemia, the most common cause of neurological death, are used to illustrate our current understanding of death signalling in neurodegenerative diseases. A better understanding of the neuronal death pathways would provide targets for the development of therapeutic interventions for these diseases.Peer reviewe

Combined suppression of CASP2 and CASP6 protects retinal ganglion cells from apoptosis and promotes axon regeneration through CNTF-mediated JAK/STAT signalling

We have previously shown that crushing the optic nerve induces death of retinal ganglion cells by apoptosis, but suppression of CASP2, which is predominantly activated in retinal ganglion cells, using a stably modified short interfering RNA CASP2, inhibits retinal ganglion cell apoptosis. Here, we report that combined delivery of short interfering CASP2 and inhibition of CASP6 using a dominant negative CASP6 mutant activates astrocytes and Müller cells, increases CNTF levels in the retina and leads to enhanced retinal ganglion cell axon regeneration. In dissociated adult rat mixed retinal cultures, dominant negative CASP6 mutant + short interfering CASP2 treatment also significantly increases GFAP(+) glial activation, increases the expression of CNTF in culture, and subsequently increases the number of retinal ganglion cells with neurites and the mean retinal ganglion cell neurite length. These effects are abrogated by the addition of MAB228 (a monoclonal antibody targeted to the gp130 component of the CNTF receptor) and AG490 (an inhibitor of the JAK/STAT pathway downstream of CNTF signalling). Similarly, in the optic nerve crush injury model, MAB228 and AG490 neutralizes dominant negative CASP6 mutant + short interfering CASP2-mediated retinal ganglion cell axon regeneration, Müller cell activation and CNTF production in the retina without affecting retinal ganglion cell survival. We therefore conclude that axon regeneration promoted by suppression of CASP2 and CASP6 is CNTF-dependent and mediated through the JAK/STAT signalling pathway. This study offers insights for the development of effective therapeutics for promoting retinal ganglion cell survival and axon regeneration

Better News about Math: A Research Agenda

Numeracy is not a luxury: numbers constantly factor into our daily lives. Yet adults in the United States have lower numeracy than adults in most other developed nations. While formal statistical training is effective, few adults receive it – and schools are a major contributor to the inequity we see among U.S. adults. That leaves news well-poised as a source of informal learning, given that news is a domain where adults regularly encounter quantitative content. Our transdisciplinary team of journalists and social scientists propose a research agenda for thinking about math and the news. We engage here in a dialogue about two recent news articles, contrasting journalist and researcher perspectives on each. We close by talking about the particular opportunities and challenges that the global COVID-19 pandemic has laid bare for both of our professions

Caspase-9 Mediates Photoreceptor Death After Blunt Ocular Trauma

PURPOSE. Ocular trauma is common in civilian and military populations. Commotio retinae involves acute disruption of photoreceptor outer segments after blunt ocular trauma, with subsequent photoreceptor apoptosis causing permanent visual impairment. The mechanisms of photoreceptor death in commotio retinae have not previously been described, although caspase-dependent death is important in other nontraumatic retinal degenerations. We assessed the role of caspase-9 as a mediator of photoreceptor death in a rat model of ballistic ocular trauma causing commotio retinae. METHODS. Bilateral commotio retinae was induced in rats by ballistic ocular trauma. Caspase-9 activity was assessed by immunohistochemistry, Western blotting, and bVAD-fmk active caspase capture. Caspase-9 was inhibited by unilateral intravitreal injection of highly specific X-linked inhibitor of apoptosis (IAP) baculoviral IAP repeat 3 (XBIR3) domain linked to the cell transduction peptide penetratin 1 (Pen-1) after ballistic injury, and the affected eyes were compared with control eyes treated with Pen-1 injection alone, and retinal function was assessed by electroretinogram a-wave amplitude and photoreceptor survival by outer nuclear layer thickness. RESULTS. Increased levels of cleaved caspase-9 were shown in photoreceptors 5 hours after injury, and catalytically active full-length caspase-9 was isolated from retinas. Photoreceptor death after commotio retinae was reduced by caspase-9 inhibition by using Pen-1-XBIR3, and electroretinographic measurements of photoreceptor function was preserved, providing structural and functional neuroprotection. CONCLUSIONS. The time course of caspase-9 activation and the neuroprotective effects of inhibition suggest that caspase-9 initiates cell death in a proportion of photoreceptors after blunt ocular trauma and that an intravitreally delivered biologic inhibitor may be an effective translational treatment strategy

Caspase-9 mediates photoreceptor death after blunt ocular trauma

PURPOSE. Ocular trauma is common in civilian and military populations. Commotio retinae involves acute disruption of photoreceptor outer segments after blunt ocular trauma, with subsequent photoreceptor apoptosis causing permanent visual impairment. The mechanisms of photoreceptor death in commotio retinae have not previously been described, although caspase-dependent death is important in other nontraumatic retinal degenerations. We assessed the role of caspase-9 as a mediator of photoreceptor death in a rat model of ballistic ocular trauma causing commotio retinae. METHODS. Bilateral commotio retinae was induced in rats by ballistic ocular trauma. Caspase-9 activity was assessed by immunohistochemistry, Western blotting, and bVAD-fmk active caspase capture. Caspase-9 was inhibited by unilateral intravitreal injection of highly specific X-linked inhibitor of apoptosis (IAP) baculoviral IAP repeat 3 (XBIR3) domain linked to the cell transduction peptide penetratin 1 (Pen-1) after ballistic injury, and the affected eyes were compared with control eyes treated with Pen-1 injection alone, and retinal function was assessed by electroretinogram a-wave amplitude and photoreceptor survival by outer nuclear layer thickness. RESULTS. Increased levels of cleaved caspase-9 were shown in photoreceptors 5 hours after injury, and catalytically active full-length caspase-9 was isolated from retinas. Photoreceptor death after commotio retinae was reduced by caspase-9 inhibition by using Pen-1–XBIR3, and electroretinographic measurements of photoreceptor function was preserved, providing structural and functional neuroprotection. CONCLUSIONS. The time course of caspase-9 activation and the neuroprotective effects of inhibition suggest that caspase-9 initiates cell death in a proportion of photoreceptors after blunt ocular trauma and that an intravitreally delivered biologic inhibitor may be an effective translational treatment strategy