ABSTRACT
BACKGROUND: Thrombolytic agents, including tenecteplase, are generally used within 4.5 hours after the onset of stroke symptoms. Information on whether tenecteplase confers benefit beyond 4.5 hours is limited. METHODS: We conducted a multicenter, double-blind, randomized, placebo-controlled trial involving patients with ischemic stroke to compare tenecteplase (0.25 mg per kilogram of body weight, up to 25 mg) with placebo administered 4.5 to 24 hours after the time that the patient was last known to be well. Patients had to have evidence of occlusion of the middle cerebral artery or internal carotid artery and salvageable tissue as determined on perfusion imaging. The primary outcome was the ordinal score on the modified Rankin scale (range, 0 to 6, with higher scores indicating greater disability and a score of 6 indicating death) at day 90. Safety outcomes included death and symptomatic intracranial hemorrhage. RESULTS: The trial enrolled 458 patients, 77.3% of whom subsequently underwent thrombectomy; 228 patients were assigned to receive tenecteplase, and 230 to receive placebo. The median time between the time the patient was last known to be well and randomization was approximately 12 hours in the tenecteplase group and approximately 13 hours in the placebo group. The median score on the modified Rankin scale at 90 days was 3 in each group. The adjusted common odds ratio for the distribution of scores on the modified Rankin scale at 90 days for tenecteplase as compared with placebo was 1.13 (95% confidence interval, 0.82 to 1.57; P = 0.45). In the safety population, mortality at 90 days was 19.7% in the tenecteplase group and 18.2% in the placebo group, and the incidence of symptomatic intracranial hemorrhage was 3.2% and 2.3%, respectively. CONCLUSIONS: Tenecteplase therapy that was initiated 4.5 to 24 hours after stroke onset in patients with occlusions of the middle cerebral artery or internal carotid artery, most of whom had undergone endovascular thrombectomy, did not result in better clinical outcomes than those with placebo. The incidence of symptomatic intracerebral hemorrhage was similar in the two groups. (Funded by Genentech; TIMELESS ClinicalTrials.gov number, NCT03785678.).
Subject(s)
Brain Ischemia , Ischemic Stroke , Perfusion Imaging , Tenecteplase , Thrombectomy , Tissue Plasminogen Activator , Humans , Brain Ischemia/diagnostic imaging , Brain Ischemia/drug therapy , Brain Ischemia/mortality , Brain Ischemia/surgery , Fibrinolytic Agents/administration & dosage , Fibrinolytic Agents/adverse effects , Fibrinolytic Agents/therapeutic use , Intracranial Hemorrhages/chemically induced , Intracranial Hemorrhages/diagnostic imaging , Perfusion , Perfusion Imaging/methods , Stroke/diagnostic imaging , Stroke/drug therapy , Stroke/mortality , Stroke/surgery , Tenecteplase/administration & dosage , Tenecteplase/adverse effects , Tenecteplase/therapeutic use , Thrombectomy/adverse effects , Thrombectomy/methods , Tissue Plasminogen Activator/administration & dosage , Tissue Plasminogen Activator/adverse effects , Tissue Plasminogen Activator/therapeutic use , Treatment Outcome , Double-Blind Method , Ischemic Stroke/diagnostic imaging , Ischemic Stroke/drug therapy , Ischemic Stroke/mortality , Ischemic Stroke/surgery , Infarction, Middle Cerebral Artery/diagnostic imaging , Infarction, Middle Cerebral Artery/drug therapy , Infarction, Middle Cerebral Artery/surgery , Carotid Artery Diseases/diagnostic imaging , Carotid Artery Diseases/drug therapy , Carotid Artery Diseases/surgery , Brain/blood supply , Brain/diagnostic imaging , Time-to-TreatmentABSTRACT
Background and Purpose: The Neurology Mortality Review Committee at our institution identified variability in location of death for patients on our inpatient neurology services. Hospice may increase the number of patients dying in their preferred locations. This study aimed to characterize patients who die on inpatient neurology services and explore barriers to discharge to hospice. Methods: This retrospective study was completed at a single, quaternary care medical center that is a Level I Trauma Center and Comprehensive Stroke Center. Patients discharged by an inpatient neurology service between 6/2019-1/2021 were identified and electronic medical record review was performed on patients who died in the hospital and who were discharged to hospice. Results: 69 inpatient deaths and 74 discharges to hospice occurred during the study period. Of the 69 deaths, 54 occurred following withdrawal of life sustaining treatment (WLST), of which 14 had a referral to hospice placed. There were 88 "hospice-referred" patients and 40 "hospice-eligible" patients. Hospice-referred patients were less likely to require the intensive care unit than hospice-eligible patients. Hospice-referred patients had their code status changed to Do Not Intubate earlier and were more likely to have advanced directives available. Conclusion: Our data highlight opportunities for further research to improve discharge to hospice including interhospital transfers, advanced directives, earlier goals of care discussions, palliative care consultations, and increased hospice bed availability. Importantly, it highlights the limitations of using in-hospital mortality as a quality indicator in this patient population.
ABSTRACT
Low doses of µ-opioid receptor (MOR) agonists rapidly ameliorate symptoms in treatment-resistant obsessive-compulsive disorder (OCD) patients (10-50% of OCD patients). However, the utility of MOR agonists is limited by their safety liabilities. We developed a novel MOR partial agonist (EPD1540) that has an improved respiratory safety profile when compared to buprenorphine. Buprenorphine is a MOR partial agonist primarily used in the treatment of opiate-use disorder, which in investigator-led trials, has been shown to rapidly ameliorate symptoms in treatment-resistant OCD patients. In this study, we show that doses of EPD1504 and buprenorphine that occupy small fractions of MORs in the CNS (approximately 20%) are as effective as fluoxetine at ameliorating OCD-like behaviors in two different rat models (an operant probabilistic reversal task and marble burying). Importantly, effective doses of EPD1504 did not impair either locomotor activity, or respiration under normoxic or hypercapnic conditions. Additionally, EPD1504 had effects comparable to buprenorphine in the conditioned place preference assay. These results indicate that EPD1504 may provide a safer alternative to buprenorphine for the treatment of OCD patients.
ABSTRACT
Structural optimization of a previously reported agonist of µOR, PZM21 is described resulting in the discovery of a novel series of amides with at least 4-folds enhanced CNS penetration in rat. Furthermore, these efforts yielded compounds with varying levels of efficacy on the receptor ranging from high efficacy agonists such as compound 20 to antagonists, such as 24. The correlation between in vitro activation of µOR and relative activity in models of analgesia for these compounds is discussed. The compelling results obtained in these studies demonstrate the potential utility of these newly discovered compounds in the treatment of pain and opioid use disorder.
Subject(s)
Opioid-Related Disorders , Pain , Rats , Animals , Pain/drug therapy , Amides , Brain/metabolism , Receptors, Opioid, mu/agonists , Analgesics, Opioid/pharmacology , Analgesics, Opioid/therapeutic useSubject(s)
Embolism , Persistent Left Superior Vena Cava , Pulmonary Veins , Stroke , Humans , Adult , Pulmonary Veins/diagnostic imaging , Pulmonary Veins/abnormalities , Vena Cava, Superior/diagnostic imaging , Vena Cava, Superior/abnormalities , Persistent Left Superior Vena Cava/complications , Stroke/diagnostic imaging , Stroke/etiology , Embolism/complicationsSubject(s)
Brain Ischemia , Endovascular Procedures , Stroke , Humans , Stroke/surgery , Thrombectomy , Treatment OutcomeABSTRACT
This article investigates whether goal-directed learning of pictures leads to multiple mental representations which are differently useful for different purposes. The paper further investigates the effects of prompts on picture processing. 136 undergraduate students were presented maps of a fictitious city. One half of the participants were instructed to learn their map as preparation to draw it from memory as precisely as possible (PrepDraw), which should stimulate the creation of an elaborated surface representation. The other half were instructed to learn the map as preparation for finding the shortest traffic connection from various locations to other locations (PrepConnect), which should stimulate the construction of a task-oriented deep-structure representation (mental model). Within both experimental groups, one-third of the participants received the map without prompts. Another third received the map with survey prompts (stimulating processing of what is where), and the final third received the map with connect prompts (stimulating processing of how train stations are connected). In the following test phase, participants received a recognition task, a recall task, and an inference task. For recognition and recall, two surface structure scores (extent, accuracy) and two deep structure scores (extent, accuracy) were calculated. The inference task served also to indicate deep structure accuracy. The PrepDraw group outperformed the PrepConnect group in terms of surface structure related variables, whereas the PrepConnect group outperformed the PrepDraw group in terms of deep structure-related variables. Map processing was not enhanced by prompts aligned with the instruction, but non-aligned prompts tended to interfere with learning.
Subject(s)
Mental Recall , Recognition, Psychology , Humans , Models, PsychologicalABSTRACT
Opioid use disorder (OUD) is a major socioeconomic burden. An ideal OUD pharmacotherapy will mitigate the suffering associated with opioid-withdrawal, inhibit the effects of high efficacy opioids, and minimize opioid-cravings while being safe and accessible to a diverse patient population. Although current OUD pharmacotherapies inhibit the euphoric effects of opioids of abuse, the extent to which they safely alleviate withdrawal and opioid-cravings corresponds with their intrinsic µ opioid receptor (MOR) efficacy. In addition to inhibiting the euphoric effects of opioids of abuse, the medium efficacy MOR agonist buprenorphine alleviates withdrawal and opioid-cravings, but its intrinsic MOR efficacy is sufficient such that its utility is limited by abuse and safety liabilities. Although the MOR antagonist naltrexone minimizes euphoria and has no abuse liability, it exacerbates suffering associated with withdrawal and opioid cravings. Therefore, a therapeutic with intrinsic MOR activity between the partial agonist (buprenorphine) and the antagonist (naltrexone) would strike a balance between the benefits and liabilities of these two therapeutics. To address this need, we derived RM1490, an MOR agonist based on a nonmorphinan scaffold that exhibits approximately half the intrinsic MOR efficacy of buprenorphine. In a series of preclinical assays, we compared RM1490 with buprenorphine and naltrexone at doses that achieve therapeutic levels of central nervous system MOR occupancy. RM1490 exhibited a behavioral profile consistent with reduced reward, dependence, and precipitated withdrawal liabilities. RM1490 was also more effective than buprenorphine at reversing the respiratory depressant effects of fentanyl and did not suppress respiration when combined with diazepam. SIGNIFICANCE STATEMENT: In preclinical studies, RM1490 has a physiological and behavioral profile suitable for opioid use disorder maintenance therapy.
Subject(s)
Opioid-Related Disorders , Buprenorphine , NaltrexoneABSTRACT
OBJECTIVE: To determine if chronic motor deficits secondary to traumatic brain injury (TBI) can be improved by implantation of allogeneic modified bone marrow-derived mesenchymal stromal/stem cells (SB623). METHODS: This 6-month interim analysis of the 1-year double-blind, randomized, surgical sham-controlled, phase 2 STEMTRA trial (NCT02416492) evaluated safety and efficacy of the stereotactic intracranial implantation of SB623 in patients with stable chronic motor deficits secondary to TBI. Patients in this multi-center trial (N = 63) underwent randomization in a 1:1:1:1 ratio to 2.5 × 106, 5.0 × 106, 10 × 106 SB623 cells or control. Safety was assessed in patients who underwent surgery (N = 61), and efficacy in the modified intent-to-treat population of randomized patients who underwent surgery (N = 61; SB623 = 46, control = 15). RESULTS: The primary efficacy endpoint of significant improvement from baseline of Fugl-Meyer Motor Scale score at 6 months for SB623-treated patients was achieved. SB623-treated patients improved by (LS mean [SE]) +8.3 (1.4) vs +2.3 (2.5) for control at 6 months, the LS mean difference was 6.0 (95% CI: 0.3-11.8); p = 0.040. Secondary efficacy endpoints improved from baseline, but were not statistically significant vs control at 6 months. There were no dose-limiting toxicities or deaths, and 100% of SB623-treated patients experienced treatment-emergent adverse events vs 93.3% of control patients (p = 0.25). CONCLUSIONS: SB623 cell implantation appeared to be safe and well tolerated, and patients implanted with SB623 experienced significant improvement from baseline motor status at 6 months compared to controls. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that implantation of SB623 was well tolerated and associated with improvement in motor status.
ABSTRACT
OBJECTIVE: The aim of this study was to evaluate the safety and clinical outcomes associated with stereotactic surgical implantation of modified bone marrow-derived mesenchymal stem cells (SB623) in patients with stable chronic ischemic stroke. METHODS: This was a 2-year, open-label, single-arm, phase 1/2a study; the selected patients had chronic motor deficits between 6 and 60 months after nonhemorrhagic stroke. SB623 cells were administered to the target sites surrounding the subcortical stroke region using MRI stereotactic image guidance. RESULTS: A total of 18 patients were treated with SB623 cells. All experienced at least 1 treatment-emergent adverse event (TEAE). No patients withdrew due to adverse events, and there were no dose-limiting toxicities or deaths. The most frequent TEAE was headache related to the surgical procedure (88.9%). Seven patients experienced 9 serious adverse events, which resolved without sequelae. In 16 patients who completed 24 months of treatment, statistically significant improvements from baseline (mean) at 24 months were reported for the European Stroke Scale (ESS) score, 5.7 (95% CI 1.4-10.1, p < 0.05); National Institutes of Health Stroke Scale (NIHSS) score, -2.1 (95% CI -3.3 to -1.0, p < 0.01), Fugl-Meyer (F-M) total score, 19.4 (95% CI 9.9-29.0, p < 0.01); and F-M motor scale score, 10.4 (95% CI 4.0-16.7, p < 0.01). Measures of efficacy reached plateau by 12 months with no decline thereafter. There were no statistically significant changes in the modified Rankin Scale score. The size of transient lesions detected by T2-weighted FLAIR imaging in the ipsilateral cortex at weeks 1-2 postimplantation significantly correlated with improvement in ESS (0.619, p < 0.05) and NIHSS (-0.735, p < 0.01) scores at 24 months. CONCLUSIONS: In this completed 2-year phase 1/2a study, implantation of SB623 cells in patients with stable chronic stroke was safe and was accompanied by improvements in clinical outcomes.Clinical trial registration no.: NCT01287936 (clinicaltrials.gov).
ABSTRACT
Although optimizing decisions between drives to avoid pain and to obtain reward are critical for survival, understanding the neuronal circuit activity that regulates choice during approach-avoidance conflicts is limited. Here, we recorded neuronal activity in the infralimbic (IL) cortex and nucleus accumbens (NAc) during an approach-avoidance task. In this task, disruption of approach by a pain-predictive cue (PPC-avoidance) is extinguished by experience and reinstated in a model of chronic pain. In the IL-NAc circuit, the activity of distinct subpopulations of neurons predicts the extent of PPC-avoidance observed. Furthermore, chemogenetic and optogenetic manipulations establish that IL-NAc circuitry regulates PPC-avoidance behavior. Our results indicate that IL-NAc circuitry is engaged during approach-avoidance conflicts, and modifications of this circuit by experience and chronic pain determine whether approach or avoidance occurs.
Subject(s)
Avoidance Learning , Cerebral Cortex/physiopathology , Chronic Pain/physiopathology , Nucleus Accumbens/physiopathology , Animals , Behavior, Animal , Cues , RewardABSTRACT
BACKGROUND AND PURPOSE: Preclinical data suggest that cell-based therapies have the potential to improve stroke outcomes. METHODS: Eighteen patients with stable, chronic stroke were enrolled in a 2-year, open-label, single-arm study to evaluate the safety and clinical outcomes of surgical transplantation of modified bone marrow-derived mesenchymal stem cells (SB623). RESULTS: All patients in the safety population (N=18) experienced at least 1 treatment-emergent adverse event. Six patients experienced 6 serious treatment-emergent adverse events; 2 were probably or definitely related to surgical procedure; none were related to cell treatment. All serious treatment-emergent adverse events resolved without sequelae. There were no dose-limiting toxicities or deaths. Sixteen patients completed 12 months of follow-up at the time of this analysis. Significant improvement from baseline (mean) was reported for: (1) European Stroke Scale: mean increase 6.88 (95% confidence interval, 3.5-10.3; P<0.001), (2) National Institutes of Health Stroke Scale: mean decrease 2.00 (95% confidence interval, -2.7 to -1.3; P<0.001), (3) Fugl-Meyer total score: mean increase 19.20 (95% confidence interval, 11.4-27.0; P<0.001), and (4) Fugl-Meyer motor function total score: mean increase 11.40 (95% confidence interval, 4.6-18.2; P<0.001). No changes were observed in modified Rankin Scale. The area of magnetic resonance T2 fluid-attenuated inversion recovery signal change in the ipsilateral cortex 1 week after implantation significantly correlated with clinical improvement at 12 months (P<0.001 for European Stroke Scale). CONCLUSIONS: In this interim report, SB623 cells were safe and associated with improvement in clinical outcome end points at 12 months. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01287936.
Subject(s)
Bone Marrow Transplantation/methods , Mesenchymal Stem Cell Transplantation/methods , Stroke/surgery , Adult , Aged , Female , Humans , Male , Middle Aged , Treatment OutcomeABSTRACT
BACKGROUND: No definitive criteria are available to confirm the diagnosis of transient ischemic attack. Inter-rater agreement between physicians regarding the diagnosis of transient ischemic attack is low, even among vascular neurologists. We developed the Precise Diagnostic Score, a diagnostic score that consists of discrete and well-defined clinical and imaging parameters, and investigated inter-rater agreement in patients with suspected transient ischemic attack. METHODS: Fellowship-trained vascular neurologists, blinded to final diagnosis, independently reviewed retrospectively identical history, physical examination, routine diagnostic studies, and brain magnetic resonance imaging (diffusion and perfusion images) from consecutive patients with suspected transient ischemic attack. Each patient was rated using the 8-point Precise Diagnostic Score score, composed of a clinical score (0-4 points) and an imaging score (0-4 points). The composite Precise Diagnostic Score determines a Precise Diagnostic Score Likelihood of Brain Ischemia Scale: 0-1 = unlikely, 2 = possible, 3 = probable, 4-8 = very likely. RESULTS: Three raters reviewed data from 114 patients. Using Precise Diagnostic Score, all three raters scored a similar percentage of the clinical events as being "probable" or "very likely" caused by brain ischemia: 57, 55, and 58%. Agreement was high for both total Precise Diagnostic Score (intraclass correlation coefficient of 0.94) and for the Likelihood of Brain Ischemia Scale (agreement coefficient of 0.84). CONCLUSIONS: Compared with prior studies, inter-rater agreement for the diagnosis of transient brain ischemia appears substantially improved with the Precise Diagnostic Score scoring system. This score is the first to include specific criteria to assess the clinical relevance of diffusion-weighted imaging and perfusion lesions and supports the added value of magnetic resonance imaging for assessing patients with suspected transient ischemic attack.
Subject(s)
Ischemic Attack, Transient/diagnosis , Aged , Brain/pathology , Female , Humans , Ischemic Attack, Transient/pathology , Magnetic Resonance Imaging , Middle Aged , Neurology , Perfusion Imaging , Physicians , Reproducibility of Results , Retrospective Studies , Single-Blind MethodABSTRACT
BACKGROUND: Magnetic resonance diffusion-weighted imaging and perfusion-weighted imaging are able to identify ischaemic 'footprints' in transient ischaemic attack. Computed tomography perfusion (CTP) may be useful for patient triage and subsequent management. To date, less than 100 cases have been reported, and none have compared computed tomography perfusion to perfusion-weighted imaging (PWI). We sought to define the yield of computed tomography perfusion for the evaluation of transient ischaemic attack. METHODS: Consecutive patients with a discharge diagnosis of possible or definite transient ischaemic event who underwent computed tomography perfusion were included in this study. The presence of an ischaemic lesion was assessed on noncontrast computed tomography, automatically deconvolved CTPTMax (Time till the residue function reaches its maximum), and when available on diffusion-weighted imaging and PWITMax maps. RESULTS: Thirty-four patients were included and 17 underwent magnetic resonance imaging. Median delay between onset and computed tomography perfusion was 4·4 h (Interquartile range [IQR]: 1·9-9·6), and between computed tomography perfusion and magnetic resonance imaging was 11 h (Interquartile range: 3·8-22). Noncontrast computed tomography was negative in all cases, while CTPTMax identified an ischaemic lesion in 12/34 patients (35%). In the subgroup of patients with multimodal magnetic resonance imaging, an ischaemic lesion was found in six (35%) patients using CTPTMax versus nine (53%) on magnetic resonance imaging (five diffusion-weighted imaging, nine perfusion-weighted imaging). The additional yield of CTPTMax over computed tomography angiography was significant in the evaluation of transient ischaemic attack (12 vs. 3, McNemar, P = 0·004). CONCLUSIONS: CTPTMax found an ischaemic lesion in one-third of acute transient ischaemic attack patients. Computed tomography perfusion may be an acceptable substitute when magnetic resonance imaging is unavailable or contraindicated, and has additional yield over computed tomography angiography. Further studies evaluating the outcome of patients with computed tomography perfusion lesions in transient ischaemic attack are justified at this time.
Subject(s)
Ischemic Attack, Transient/diagnosis , Tomography, X-Ray Computed , Aged , Aged, 80 and over , Diffusion Magnetic Resonance Imaging , Female , Humans , Image Processing, Computer-Assisted , Male , Middle Aged , Perfusion , Retrospective StudiesABSTRACT
Several symptoms associated with chronic pain, including fatigue and depression, are characterized by reduced motivation to initiate or complete goal-directed tasks. However, it is unknown whether maladaptive modifications in neural circuits that regulate motivation occur during chronic pain. Here, we demonstrate that the decreased motivation elicited in mice by two different models of chronic pain requires a galanin receptor 1-triggered depression of excitatory synaptic transmission in indirect pathway nucleus accumbens medium spiny neurons. These results demonstrate a previously unknown pathological adaption in a key node of motivational neural circuitry that is required for one of the major sequela of chronic pain states and syndromes.
Subject(s)
Chronic Pain/physiopathology , Chronic Pain/psychology , Long-Term Synaptic Depression/physiology , Motivation , Nucleus Accumbens/physiopathology , Receptor, Galanin, Type 1/physiology , Animals , Disease Models, Animal , Gene Knockdown Techniques , Long-Term Synaptic Depression/drug effects , Male , Mice , Mice, Inbred C57BL , Receptor, Galanin, Type 1/antagonists & inhibitors , Receptor, Galanin, Type 1/geneticsABSTRACT
PURPOSE: Cervical artery dissections (CDs) are among the most common causes of stroke in young and middle-aged adults. The aim of this scientific statement is to review the current state of evidence on the diagnosis and management of CDs and their statistical association with cervical manipulative therapy (CMT). In some forms of CMT, a high or low amplitude thrust is applied to the cervical spine by a healthcare professional. METHODS: Members of the writing group were appointed by the American Heart Association Stroke Council's Scientific Statements Oversight Committee and the American Heart Association's Manuscript Oversight Committee. Members were assigned topics relevant to their areas of expertise and reviewed appropriate literature, references to published clinical and epidemiology studies, morbidity and mortality reports, clinical and public health guidelines, authoritative statements, personal files, and expert opinion to summarize existing evidence and to indicate gaps in current knowledge. RESULTS: Patients with CD may present with unilateral headaches, posterior cervical pain, or cerebral or retinal ischemia (transient ischemic or strokes) attributable mainly to artery-artery embolism, CD cranial nerve palsies, oculosympathetic palsy, or pulsatile tinnitus. Diagnosis of CD depends on a thorough history, physical examination, and targeted ancillary investigations. Although the role of trivial trauma is debatable, mechanical forces can lead to intimal injuries of the vertebral arteries and internal carotid arteries and result in CD. Disability levels vary among CD patients with many having good outcomes, but serious neurological sequelae can occur. No evidence-based guidelines are currently available to endorse best management strategies for CDs. Antiplatelet and anticoagulant treatments are both used for prevention of local thrombus and secondary embolism. Case-control and other articles have suggested an epidemiologic association between CD, particularly vertebral artery dissection, and CMT. It is unclear whether this is due to lack of recognition of preexisting CD in these patients or due to trauma caused by CMT. Ultrasonography, computed tomographic angiography, and magnetic resonance imaging with magnetic resonance angiography are useful in the diagnosis of CD. Follow-up neuroimaging is preferentially done with noninvasive modalities, but we suggest that no single test should be seen as the gold standard. CONCLUSIONS: CD is an important cause of ischemic stroke in young and middle-aged patients. CD is most prevalent in the upper cervical spine and can involve the internal carotid artery or vertebral artery. Although current biomechanical evidence is insufficient to establish the claim that CMT causes CD, clinical reports suggest that mechanical forces play a role in a considerable number of CDs and most population controlled studies have found an association between CMT and VAD stroke in young patients. Although the incidence of CMT-associated CD in patients who have previously received CMT is not well established, and probably low, practitioners should strongly consider the possibility of CD as a presenting symptom, and patients should be informed of the statistical association between CD and CMT prior to undergoing manipulation of the cervical spine.
Subject(s)
Manipulation, Spinal/adverse effects , Vertebral Artery Dissection/diagnosis , Vertebral Artery Dissection/etiology , Vertebral Artery Dissection/therapy , American Heart Association , Humans , Stroke/etiology , United StatesABSTRACT
This protocol describes the targeted introduction of fluorophore in the form of a dye or genetic material into single cells. This method has the advantage of producing true single-cell chimeric animals in which to study the effects of overexpression or knockdown of a gene in an otherwise entirely wild-type background.
Subject(s)
Brain/cytology , Cytological Techniques/methods , Neurons/physiology , Staining and Labeling/methods , Xenopus/embryology , Animals , Fluorescent Dyes/metabolism , Larva/cytology , Luminescent Proteins/genetics , Luminescent Proteins/metabolismABSTRACT
In vivo fluorescence imaging of cells in the developing nervous system is greatly facilitated in specimens in which cells are brightly but sparsely labeled. In this article, we describe a number of techniques that can be used for delivering fluorophore to neurons in the albino Xenopus laevis tadpole. Fluorescent dye or DNA that encodes a fluorescent protein can be delivered to single cells by electroporation. Alternatively, multiple cells can be labeled with fluorescent dye introduced by local iontophoresis or with plasmid DNA introduced by bulk electroporation. Technical considerations and analysis methods for time-lapse imaging in living tissue are also discussed.
Subject(s)
Nervous System/embryology , Neurons/physiology , Staining and Labeling/methods , Time-Lapse Imaging/methods , Xenopus laevis/embryology , Animals , Fluorescent Dyes/metabolism , Luminescent Proteins/biosynthesis , Luminescent Proteins/geneticsABSTRACT
Individual neurons in the developing nervous system can be visualized by the targeted delivery of a fluorophore. In this article, we describe a method for introducing a fluorescent dye via iontophoresis into retinal ganglion cell (RGC) axons in albino Xenopus laevis tadpoles. Iontophoresis is the enhanced permeation of molecules across biological membranes under the influence of an electrical field. Lipophilic dyes such as DiI are well suited to this method--being insoluble in the aqueous environment of the eye, they precipitate instantaneously, and only cells in contact with the dye crystal are labeled as the dye diffuses through the plasma membrane. A dissection stereomicroscope is used to allow a wide range of approach angles for the micropipette. The goal is to introduce a small bolus of dye into the neural retina where the ganglion cell somata are located and the axons course, with the expectation that it will be taken up by a small enough number of axons to allow individual cells to be distinguished. Because RGC axons will typically be imaged in the tectum far from the injection site, a relatively large injection can be made, increasing the probability of labeling axons without obscuring their visualization at the target. This approach is particularly useful under conditions in which it might be too difficult to perform juxtacellular electroporation because of limited visibility or access.