Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 74
Filtrar
2.
Exp Neurol ; 374: 114727, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38360257

RESUMO

Previous studies have demonstrated that endogenous tissue-type plasminogen activator (tPA) is upregulated in the brain after an acute ischemic stroke (AIS). While mixed results were observed in genetic models, the pharmacological inhibition of endogenous tPA showed beneficial effects. Treatment with exogenous recombinant tPA exacerbated brain damage in rodent models of stroke. Despite the detrimental effects of tPA in ischemic stroke, recombinant tPA is administered to AIS patients to recanalize the occluded blood vessels because the benefits of its administration outweigh the risks associated with tPA upregulation and increased activity. We hypothesized that tPA knockdown following recanalization would ameliorate sensorimotor deficits and reduce brain injury. Young male and female rats (2-3 months old) were subjected to transient focal cerebral ischemia by occlusion of the right middle cerebral artery. Shortly after reperfusion, rats from appropriate cohorts were administered a nanoparticle formulation containing tPA shRNA or control shRNA plasmids (1 mg/kg) intravenously via the tail vein. Infarct volume during acute and chronic phases, expression of matrix metalloproteinases (MMPs) 1, 3, and 9, enlargement of cerebral ventricle volume, and white matter damage were all reduced by shRNA-mediated gene silencing of tPA following reperfusion. Additionally, recovery of somatosensory and motor functions was improved. In conclusion, our results provide evidence that reducing endogenous tPA following recanalization improves functional outcomes and reduces post-stroke brain damage.


Assuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Humanos , Ratos , Masculino , Feminino , Animais , Lactente , Ativador de Plasminogênio Tecidual , AVC Isquêmico/tratamento farmacológico , Isquemia Encefálica/metabolismo , Acidente Vascular Cerebral/tratamento farmacológico , Acidente Vascular Cerebral/patologia , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/uso terapêutico , Fibrinolíticos/uso terapêutico , Fibrinolíticos/farmacologia , Modelos Animais de Doenças
3.
J Neurosurg Case Lessons ; 6(15)2023 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-37910017

RESUMO

BACKGROUND: Spinal arteriovenous fistulas (SAVFs) are underdiagnosed entities that can lead to severe morbidity from spinal cord dysfunction or hemorrhage. Treatment options include endovascular embolization or direct surgical obliteration at the level of the arteriovenous shunt. The authors present a case of intraluminal microsurgical access for occlusion with a hemostatic agent of a type IV SAVF near the conus medullaris as an alternative to clip occlusion to avoid nerve root compromise. OBSERVATIONS: Temporary microsurgical clipping of the SAVF led to nerve root compromise detected via intraoperative monitoring. Instead, the authors advanced elongated pieces of a hemostatic agent directly into the arterial lumen via arteriotomy to create direct obliteration of the fistula without intraoperative monitoring changes. LESSONS: In patients unable to tolerate clipping of the SAVF because of nerve root involvement and neurophysiological signal decline, open access of the vessels and direct intraluminal obliteration using a hemostatic agent should be considered as an alternative method of fistula occlusion.

4.
Cureus ; 15(5): e39402, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37362538

RESUMO

Background Passing the American Board of Neurological Surgeons (ABNS) Primary Exam is required for residents in training. Both the program directors and residents are given keywords of the exam afterward in the hope to help program directors determine their relative strengths and weakness. We have organized and tabulated these keywords for neurosurgery residents' benefit. Methodology We collected and analyzed ABNS Primary Exam keywords (2015-2023) in each of the exam's main categories for trends and recurrences. We examined the overall passing rates among first-time credit test takers. The frequency of each subcategory was calculated as a percentage within its corresponding category. Recurrent keywords were grouped together with their corresponding years and categorized as once, twice, or thrice and greater occurrences; the last category was considered to be high-yield keywords. Results The number of questions in Neurosciences and Neurology has decreased over the years while Neurosurgery and Critical Care questions have increased. Similarly, there are fewer keyword repeats in Neurosciences and Neurology. The most repeated keywords are in Neuroimaging. The most common keywords are presented and listed along with the years of occurrences. Overall, the passing rate among first-time credit test takers is over 90%. Conclusions Neurosurgery residents can consider the common keywords as a guide in preparation for the ABNS Primary Exam.

6.
Front Neurosci ; 16: 1012812, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36267234

RESUMO

We recently showed that the post-ischemic induction of matrix metalloproteinase-12 (MMP-12) in the brain degrades tight junction proteins, increases MMP-9 and TNFα expression, and contributes to the blood-brain barrier (BBB) disruption, apoptosis, demyelination, and infarct volume development. The objectives of this study were to (1) determine the effect of MMP-12 suppression by shRNA-mediated gene silencing on neurological/functional recovery, (2) establish the optimal timing of MMP-12shRNA treatment that provides maximum therapeutic benefit, (3) compare the effectiveness of acute versus chronic MMP-12 suppression, and (4) evaluate potential sex-related differences in treatment outcomes. Young male and female Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion and reperfusion. Cohorts of rats were administered either MMP-12shRNA or scrambled shRNA sequence (control) expressing plasmids (1 mg/kg; i.v.) formulated as nanoparticles. At designated time points after reperfusion, rats from various groups were subjected to a battery of neurological tests to assess their reflex, balance, sensory, and motor functions. Suppression of MMP-12 promoted the neurological recovery of stroke-induced male and female rats, although the effect was less apparent in females. Immediate treatment after reperfusion resulted in a better recovery of sensory and motor function than delayed treatments. Chronic MMP-12 suppression neither enhanced nor diminished the therapeutic effects of acute MMP-12 suppression, indicating that a single dose of plasmid may be sufficient. We conclude that suppressing MMP-12 after an ischemic stroke is a promising therapeutic strategy for promoting the recovery of neurological function.

7.
Neurochem Int ; 161: 105436, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36283468

RESUMO

Tissue-type plasminogen activator (t-PA) expression is known to increase following transient focal cerebral ischemia and reperfusion. Previously, we reported downregulation of t-PA upon suppression of matrix metalloproteinase-12 (MMP-12), following transient focal cerebral ischemia and reperfusion. We now present data on the temporal expression of t-PA in the brain after transient ischemia, as well as the interaction between MMP-12 and t-PA, two proteases associated with the breakdown of the blood-brain barrier (BBB) and ischemic brain damage. We hypothesized that there might be reciprocal interactions between MMP-12 and t-PA in the brain after ischemic stroke. This hypothesis was tested using shRNA-mediated gene silencing and computational modeling. Suppression of t-PA following transient ischemia and reperfusion in rats attenuated MMP-12 expression in the brain. The overall effect of t-PA shRNA administration was to attenuate the degradation of BBB tight junction protein claudin-5, diminish BBB disruption, and reduce neuroinflammation by decreasing the expression of the microglia/macrophage pro-inflammatory M1 phenotype (CD68, iNOS, IL-1ß, and TNFα). Reduced BBB disruption and subsequent lack of infiltration of macrophages (the main source of MMP-12 in the ischemic brain) could account for the decrease in MMP-12 expression after t-PA suppression. Computational modeling of in silico protein-protein interactions indicated that MMP-12 and t-PA may interact physically. Overall, our findings demonstrate that MMP-12 and t-PA interact directly or indirectly at multiple levels in the brain following an ischemic stroke. The present findings could be useful in the development of new pharmacotherapies for the treatment of stroke.


Assuntos
Isquemia Encefálica , Ataque Isquêmico Transitório , AVC Isquêmico , Metaloproteinase 12 da Matriz , Ativador de Plasminogênio Tecidual , Animais , Ratos , Barreira Hematoencefálica/metabolismo , Encéfalo/metabolismo , Isquemia Encefálica/metabolismo , Ataque Isquêmico Transitório/metabolismo , AVC Isquêmico/metabolismo , Metaloproteinase 12 da Matriz/metabolismo , RNA Interferente Pequeno/genética , Ativador de Plasminogênio Tecidual/metabolismo
8.
Clin Neurol Neurosurg ; 220: 107353, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35835022

RESUMO

OBJECTIVE: Routine post-bleed day 7 (PBD7) angiography has been utilized to evaluate for vasospasm in aneurysmal subarachnoid hemorrhage (SAH). We sought to assess the rate of delayed-cerebral ischemia (DCI) associated with angiographic vasospasm following negative PBD7 angiography. METHODS: Retrospective review of 178 aneurysmal SAH patients was performed. Patients underwent routine angiography on or around 7 days after hemorrhage. Primary variables assessed were the rate of vasospasm detection on PBD7 angiograms and rate of subsequent development of delayed-cerebral ischemia (DCI) associated with angiographic vasospasm in patients without spasm on PBD7. Statistical analysis was carried out for contributing factors. RESULTS: Eighty-four of 178 patients (47.2 %) developed angiographically proven vasospasm during their hospital course. Seven patients (3.9 %) were clinically suspected to have vasospasm prior to PBD7 with radiographic confirmation. Sixty-nine patients (38.8%) demonstrated novel spasm on routine PBD7 angiogram, with 56.5 % of these patients showing vasospasm on angiography obtained after PBD7 for DCI. One hundred and two patients (57.3 %) had no vasospasm on routine PBD7 angiography. Eight patients in the PBD7 spasm-free subgroup went on to develop DCI with angiographic spasm. These 8 patients represent 4.5 % (8/178) of all patients, 7.8 % (8/102) of the PBD7 negative subgroup, and 9.5 % (8/84) of patients with angiographic spasm during admission. CONCLUSION: The majority of patients (90.4 %) with angiographic vasospasm manifested on or before PBD7. DCI with angiographically-proven spasm arouse infrequently (7.8 %) after negative PBD7 angiography. Further study of PBD7 angiography may help determine which SAH patients in whom shortened length-of-stay might safely be pursued.


Assuntos
Isquemia Encefálica , Hemorragia Subaracnóidea , Vasoespasmo Intracraniano , Isquemia Encefálica/complicações , Isquemia Encefálica/etiologia , Angiografia Cerebral , Infarto Cerebral/complicações , Humanos , Hemorragia Subaracnóidea/complicações , Hemorragia Subaracnóidea/diagnóstico por imagem , Vasoespasmo Intracraniano/complicações , Vasoespasmo Intracraniano/etiologia
9.
Int J Oncol ; 58(5)2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33878845

RESUMO

Following the publication of the above paper, we were contacted by the University of Illinois at Chicago, to request the retraction of the above article. Following a formal institutional investigation, the investigation panel concluded that the images in question had falsifying elements. Regarding the above study, the specific allegations that were investigated were that of falsifying elements of Fig. 6A, row 2, columns 2 and 3. Following a review of this paper conducted independently by the Editor of International Journal of Oncology, the Editor concurred with the conclusions of the investigation panel, and therefore the above paper has been retracted from the publication. We also tried to contact the authors, but did not receive a reply. The Editor apologizes to the readership for the inconvenience caused.[the original article was published in International Journal of Oncology 40: 509­518, 2012; DOI: 10.3892/ijo.2011.1255].

10.
Int J Oncol ; 58(4)2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33655319

RESUMO

Following the publication of the above paper, we were contacted by the University of Illinois at Chicago, to request the retraction of the above article. Following a formal institutional investigation, the investigation panel concluded that the images in question had falsifying elements. Regarding the above study, the specific allegations that were investigated were that of falsifying elements of Fig. 1B, bottom panel, columns 2 and 3; Fig. 4A, top panel, columns 4, 5 and 6, and middle panel, columns 1, 2 and 3; and Fig. 7D, row 1, column 1 and row 2, column 1.
Following a review of this paper conducted independently by the Editor of International Journal of Oncology, the Editor concurred with the conclusions of the investigation panel, and therefore the above paper has been retracted from the publication. We also tried to contact the authors, but did not receive a reply. The Editor apologizes to the readership for the inconvenience caused. [the original article was published in International Journal of Oncology 38: 973­983, 2011; DOI: 10.3892/ijo.2011.934]

.

11.
Int J Oncol ; 58(4)2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33655324

RESUMO

Following the publication of the above paper, we were contacted by the University of Illinois at Chicago, to request the retraction of the above article. Following a formal institutional investigation, the investigation panel concluded that the images in question had falsifying elements. Regarding the above study, the specific allegations that were investigated were that of falsifying elements of Fig. 2A, right panel, row 3, columns 2, 3 and 4 and Fig. 4D, left panel, row 5, columns 1, 2 and 3; Fig. 4A, row 1, columns 2, 3 and 4, and Fig. 4C, row 1, columns 5, 6 and 7; and Fig. 6C, row 1, column 3, and row 2, column 1.
Following a review of this paper conducted independently by the Editor of International Journal of Oncology, the Editor concurred with the conclusions of the investigation panel, and therefore the above paper has been retracted from the publication. We also tried to contact the authors, but did not receive a reply. The Editor apologizes to the readership for the inconvenience caused. [the original article was published in International Journal of Oncology 40: 1615-1624, 2012; DOI: 10.3892/ijo.2011.987].

12.
Stroke Vasc Neurol ; 6(4): 519-527, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-33741744

RESUMO

BACKGROUND AND PURPOSE: The therapeutic potential of different stem cells for ischaemic stroke treatment is intriguing and somewhat controversial. Recent results from our laboratory have demonstrated the potential benefits of human umbilical cord blood-derived mesenchymal stem cells (MSC) in a rodent stroke model. We hypothesised that MSC treatment would effectively promote the recovery of sensory and motor function in both males and females, despite any apparent sex differences in post stroke brain injury. METHODS: Transient focal cerebral ischaemia was induced in adult Sprague-Dawley rats by occlusion of the middle cerebral artery. Following the procedure, male and female rats of the untreated group were euthanised 1 day after reperfusion and their brains were used to estimate the resulting infarct volume and tissue swelling. Additional groups of stroke-induced male and female rats were treated with MSC or vehicle and were subsequently subjected to a battery of standard neurological/neurobehavioral tests (Modified Neurological Severity Score assessment, adhesive tape removal, beam walk and rotarod). The tests were administered at regular intervals (at days 1, 3, 5, 7 and 14) after reperfusion to determine the time course of neurological and functional recovery after stroke. RESULTS: The infarct volume and extent of swelling of the ischaemic brain were similar in males and females. Despite similar pathological stroke lesions, the clinical manifestations of stroke were more pronounced in males than females, as indicated by the neurological scores and other tests. MSC treatment significantly improved the recovery of sensory and motor function in both sexes, and it demonstrated efficacy in both moderate stroke (females) and severe stroke (males). CONCLUSIONS: Despite sex differences in the severity of post stroke outcomes, MSC treatment promoted the recovery of sensory and motor function in male and female rats, suggesting that it may be a promising treatment for stroke.


Assuntos
Isquemia Encefálica , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais , Acidente Vascular Cerebral , Animais , Modelos Animais de Doenças , Feminino , Masculino , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/patologia , Ratos , Ratos Sprague-Dawley , Acidente Vascular Cerebral/terapia
13.
Transl Stroke Res ; 12(5): 923-936, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-33426628

RESUMO

The intense inflammatory response triggered in the brain after focal cerebral ischemia is detrimental. Recently, we showed that the suppression of toll-like receptors (TLRs) 2 and 4 attenuates infarct size and reduces the expression of pro-inflammatory cytokines in the ischemic brain. In this study, we further examined the effect of unsuppressed induction of TLRs 2 and 4 on the expression of its downstream signaling molecules and pro-inflammatory cytokines 1 week after reperfusion. The primary purpose of this study was to investigate the effect of simultaneous knockdown of TLRs 2 and 4 on M1/M2 microglial polarization dynamics and post-stroke neurological deficits and the recovery. Transient focal cerebral ischemia was induced in young adult male Sprague-Dawley rats by the middle cerebral artery occlusion (MCAO) procedure using a monofilament suture. Appropriate cohorts of rats were treated with a nanoparticle formulation of TLR2shRNA and TLR4shRNA (T2sh+T4sh) expressing plasmids (1 mg/kg each of T2sh and T4sh) or scrambled sequence inserted vector (vehicle control) expressing plasmids (2 mg/kg) intravenously via tail vein immediately after reperfusion. Animals from various cohorts were euthanized during reperfusion, and the ischemic brain tissue was isolated and utilized for PCR followed by agarose gel electrophoresis, real-time PCR, immunoblot, and immunofluorescence analysis. Appropriate groups were subjected to a battery of standard neurological tests at regular intervals until 14 days after reperfusion. The increased expression of both TLRs 2 and 4 and their downstream signaling molecules including the pro-inflammatory cytokines was observed even at 1-week after reperfusion. T2sh+T4sh treatment immediately after reperfusion attenuated the post-ischemic inflammation, preserved the motor function, and promoted recovery of the sensory and motor functions. We conclude that the post-ischemic induction of TLRs 2 and 4 persists for at least 7 days after reperfusion, contributes to the severity of acute inflammation, and impedes neurological recovery. Unlike previous studies in TLRs 2 or 4 knockout models, results of this study in a pharmacologically relevant preclinical rodent stroke model have translational significance.


Assuntos
Isquemia Encefálica , Traumatismo por Reperfusão , Acidente Vascular Cerebral , Animais , Infarto da Artéria Cerebral Média , Inflamação/etiologia , Masculino , Ratos , Ratos Sprague-Dawley , Traumatismo por Reperfusão/tratamento farmacológico
14.
J Neurosurg Case Lessons ; 2(18): CASE21268, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36061626

RESUMO

BACKGROUND: Sectioning the C2 nerve root is increasingly utilized during posterior C1-2 fusion, as the nerve overlies the entry point for C1 lateral mass screws and the C1-2 joint. Nerve sectioning improves visualization for screw placement and enables joint decortication for arthrodesis. While rare, vascular injury is a devastating complication of atlantoaxial fusion. Anomalous vascular anatomy at C1-2 greatly increases risk of iatrogenic injury. OBSERVATIONS: A 78-year-old female with rheumatoid arthritis and prior C2-7 fusion presented with myelopathy from a compressive pannus at C1-2. She underwent C1 laminectomy and C1-2 posterior instrumented fusion. Intraoperatively, arterial bleeding occurred as the right C2 nerve root was sectioned. Vertebral artery injury was suspected, and tamponade was performed while vascular control was established. The artery passed aberrantly beneath the nerve root in the C1-2 foramen. It was repaired microsurgically, and patency was confirmed using indocyanine green. The remainder of the fusion was aborted. The patient wore a cervical collar and was treated with aspirin for 6 weeks before undergoing instrumented fusion. The patient suffered no deficits. LESSONS: Although rare, anomalous vertebral artery anatomy increases risk of injury at time of C2 nerve root sectioning. Preoperative assessment of the vasculature is vital.

15.
Neuromolecular Med ; 21(4): 529-539, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31077035

RESUMO

Emerging stroke literature suggests that treatment of experimentally induced stroke with stem cells offered post-stroke neuroprotection via exosomes produced by these cells. Treatment with exosomes has great potential to overcome the limitations associated with cell-based therapies. However, in our preliminary studies, we noticed that the exosomes released from human umbilical cord blood-derived mesenchymal stem cells (MSCs) under standard culture conditions did not improve the post-stroke neurological outcome. Because of this apparent discrepancy, we hypothesized that exosome characteristics vary with the conditions of their production. Specifically, we suggest that the exosomes produced from the cocultures of regular and oxygen-glucose-deprived (OGD) MSCs in vitro would represent the exosomes produced from MSCs that are exposed to ischemic brain cells in vivo, and offer similar therapeutic benefits that the cell treatment would provide. We tested the efficacy of therapy with exosomes secreted from human umbilical cord blood (HUCB)-derived MSCs under in vitro hypoxic conditions on post-stroke brain damage and neurological outcome in a rat model of transient focal cerebral ischemia. We performed the TTC staining procedure as well as the neurological tests including the modified neurological severity scores (mNSS), the modified adhesive removal (sticky-tape), and the beam walking tests before ischemia and at regular intervals until 7 days reperfusion. Treatment with exosomes obtained from the cocultures of normal and OGD-induced MSCs reduced the infarct size and ipsilateral hemisphere swelling, preserved the neurological function, and facilitated the recovery of stroke-induced rats. Based on the results, we conclude that the treatment with exosomes secreted from MSCs at appropriate experimental conditions attenuates the post-stroke brain damage and improves the neurological outcome.


Assuntos
Dano Encefálico Crônico/prevenção & controle , Isquemia Encefálica/terapia , Exossomos , Células-Tronco Mesenquimais/metabolismo , Traumatismo por Reperfusão/prevenção & controle , Animais , Peso Corporal , Dano Encefálico Crônico/etiologia , Dano Encefálico Crônico/patologia , Isquemia Encefálica/complicações , Hipóxia Celular , Técnicas de Cocultura , Sangue Fetal/citologia , Glucose/farmacologia , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/biossíntese , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/fisiologia , Masculino , Oxigênio/farmacologia , Equilíbrio Postural , Desempenho Psicomotor , Ratos , Traumatismo por Reperfusão/etiologia , Regulação para Cima
16.
Cell Physiol Biochem ; 52(6): 1280-1291, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31026391

RESUMO

BACKGROUND/AIMS: Recent studies demonstrated that the treatment with mesenchymal stem cells (MSCs) obtained from the human umbilical cord blood improved survival, reduced brain damage, prevented apoptosis, suppressed inflammatory responses, downregulated the DNA damage-inducing genes, upregulated the DNA repair genes, and facilitated neurological recovery in stroke-induced animals. Emerging stroke literature supports the concept that the exosomes released from MSCs are the primary biological principles underlying the post-stroke neuroprotection offered by MSCs treatment. METHODS: Because the treatment with exosomes has a great potential to overcome the limitations associated with cell-based therapies, we tested the efficacy of exosomes secreted from HUCB-MSCs under standard culture conditions on post-stroke brain damage and neurological outcome in a rat model of ischemic stroke by performing TTC staining as well as the modified neurological severity scores, modified adhesive removal, beam-walking, and accelerating Rotarod performance tests before ischemia and at regular intervals until seven days reperfusion. RESULTS: Exosomes treatment attenuated the infarct size. Treatment with exosomes did not affect the post-stroke survival rate and body weight changes, but exacerbated the somatosensory and motor dysfunction and adversely affected the natural recovery that occurs without any treatment. CONCLUSION: Treatment with exosomes secreted from HUCB-MSCs under standard culture conditions attenuates the ischemic brain damage but does not improve the post-stroke neurological outcome.


Assuntos
Encéfalo/patologia , Exossomos/transplante , Células-Tronco Mesenquimais/citologia , Acidente Vascular Cerebral/terapia , Animais , Encéfalo/fisiopatologia , Linhagem Celular , Modelos Animais de Doenças , Masculino , Atividade Motora , Ratos Sprague-Dawley , Acidente Vascular Cerebral/patologia , Acidente Vascular Cerebral/fisiopatologia , Resultado do Tratamento
17.
Stroke Vasc Neurol ; 3(3): 153-159, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30294471

RESUMO

Background and purpose: Recent reports from our laboratory demonstrated the post-ischaemic expression profile of various matrix metalloproteinases (MMPs) in rats and the detrimental role of MMP-12 in post-stroke brain damage. We hypothesise that the post-stroke dysregulation of MMPs is similar across species and that genetic deletion of MMP-12 would not affect the post-stroke expression of other MMPs. We tested our hypothesis by determining the pre-ischaemic and post-ischaemic expression profile of MMPs in wild-type and MMP-12 knockout mice. Methods: Focal cerebral ischaemia was induced in wild-type and MMP-12 knockout mice by middle cerebral artery occlusion procedure by insertion of a monofilament suture. One hour after ischaemia, reperfusion was initiated by removing the monofilament. One day after reperfusion, ischaemic brain tissues from various groups of mice were collected, and total RNA was isolated and subjected to cDNA synthesis followed by PCR analysis. Results: Although the post-stroke expression profile of MMPs in the ischaemic brain of mice is different from rats, there is a clear species similarity in the expression of MMP-12, which was found to be predominantly upregulated in both species. Further, the post-stroke induction or inhibition of various MMPs in MMP-12 knockout mice is different from their respective expression profile in wild-type mice. Moreover, the brain mRNA expression profile of various MMPs in MMP-12 knockout mice under normal conditions is also different to their expression in wild-type mice. Conclusions: In the ischaemic brain, MMP-12 upregulates several fold higher than any other MMP. Mice derived with the genetic deletion of MMP-12 are constitutive and have altered MMP expression profile both under normal and ischaemic conditions.


Assuntos
Deleção de Genes , Infarto da Artéria Cerebral Média/enzimologia , Metaloproteinase 12 da Matriz/deficiência , RNA Mensageiro/metabolismo , Transcriptoma , Animais , Modelos Animais de Doenças , Regulação Enzimológica da Expressão Gênica , Infarto da Artéria Cerebral Média/genética , Masculino , Metaloproteinase 12 da Matriz/genética , Camundongos Endogâmicos C57BL , Camundongos Knockout , RNA Mensageiro/genética , Ratos , Especificidade da Espécie , Fatores de Tempo
18.
Front Neurol ; 9: 358, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29892257

RESUMO

BACKGROUND: Infratentorial siderosis (iSS) is a progressive degenerative disorder targeting primarily the cerebellum and cranial nerve eighth; therefore, progressive ataxia and its neuro-otological findings are common. Toxicity from hemosiderin involves selectively vulnerable neurons and glia in these posterior fossa structures. Other neurologic findings may be present, though our focus relates to the cochlea-vestibular cerebellar involvement. Radiographic evidence of siderosis may be the result of recurrent, albeit covert bleeding in the subarachnoid space, or the consequence of an overt post-traumatic or aneurysmal subarachnoid hemorrhage (SAH). The radiographic iSS appearance is identical regardless of the SAH cause. A recent study provides compelling evidence to search and correct possible hemorrhage sources in the spinal canal. The removal of residual existing hemosiderin deposits that may potentially cause clinical symptoms remains as a major therapeutic challenge. METHODS: We reviewed large data sources and identified salient papers that describe the pathogenesis, clinical and neurotologic manifestations, and the radiographic features of iSS. RESULTS: The epidemiology of iSS is unknown. In a recent series, clinically evident iSS was associated with recurrent SAH; by contrast, in a follow-up period ranging from weeks up to 11 years after a monophasic episode of SAH, radiographic siderosis was clinically silent. However, the post-aneurysmal or post-trauma SAH sample size in this single study was small and their observation period relatively short; moreover, the burden of intraneuronal hemosiderin is likely greater with recurrent SAH. There are a few reports of late iSS, several decades after traumatic SAH. A recent report found subjective hearing loss in aneurysmal SAH individuals with radiographic siderosis. Only in recent years, it is safe to perform magnetic resonance imaging (MRI) in post-aneurysmal SAH, because of the introduction of titanium, MRI-compatible aneurysm clips. CONCLUSION: iSS can be associated with significant neurotologic and cerebellar morbidity; the recurrent SAH variant is frequently clinically symptomatic, has a shorter latency and greater neurotologic disability. In these cases, a thorough search and management of a covert source of bleeding may stop clinical progression. The frequency and clinical course of radiographic iSS after traumatic and post-aneurysmal SAH is largely unknown. Detection of radiographic iSS after trauma or aneurysm bleeding suggests that the slower clinical course could benefit from an effective intervention if it became available. The use of cochlear implants is a valid alternative with advanced hearing impairment.

20.
Neuroscience ; 373: 82-91, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29337240

RESUMO

Toll-like receptor 2 (TLR2) and TLR4 belong to a family of highly conserved pattern recognition receptors and are well-known upstream sensors of signaling pathways of innate immunity. TLR2 and TLR4 upregulation is thought to be associated with poor outcome in stroke patients. We currently show that transient focal ischemia in adult rats induces TLR2 and TLR4 expression within hours and shRNA-mediated knockdown of TLR2 and TLR4 alone and in combination decreases the infarct size and swelling. We further show that TLR2 and TLR4 knockdown also prevented the induction of their downstream signaling molecules MyD88, IRAK1, and NFκB p65 as well as the pro-inflammatory cytokines IL-1ß, IL-6, and TNFα. This study thus shows that attenuation of the severity of TLR2- and TLR4-mediated post-stroke inflammation ameliorates ischemic brain damage.


Assuntos
Isquemia Encefálica/metabolismo , Isquemia Encefálica/terapia , Inflamação/metabolismo , Inflamação/prevenção & controle , Receptor 2 Toll-Like/genética , Receptor 4 Toll-Like/genética , Animais , Edema Encefálico/etiologia , Edema Encefálico/metabolismo , Edema Encefálico/prevenção & controle , Isquemia Encefálica/complicações , Modelos Animais de Doenças , Escherichia coli , Técnicas de Silenciamento de Genes , Inflamação/etiologia , Quinases Associadas a Receptores de Interleucina-1/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Masculino , Fator 88 de Diferenciação Mieloide/metabolismo , Proteínas de Neoplasias/metabolismo , Neuroproteção/fisiologia , Proteínas de Transporte Nucleocitoplasmático/metabolismo , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/administração & dosagem , Distribuição Aleatória , Ratos Sprague-Dawley , Fator de Necrose Tumoral alfa/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA